From 2e985fdb7e54293695a2a386e06e59d441efbe0f Mon Sep 17 00:00:00 2001
From: Chen Ni <nichen@iscas.ac.cn>
Date: Mon, 7 Apr 2025 15:54:05 +0800
Subject: objtool: Remove unneeded semicolon

Remove unnecessary semicolons reported by Coccinelle/coccicheck and the
semantic patch at scripts/coccinelle/misc/semicolon.cocci.

Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/builtin-check.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 0f6b197cfcb0..fcd4a6517896 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -243,7 +243,7 @@ static void save_argv(int argc, const char **argv)
 			ERROR_GLIBC("strdup(%s)", argv[i]);
 			exit(1);
 		}
-	};
+	}
 }
 
 void print_args(void)
-- 
cgit v1.2.3


From be8374a5ba7cbab6b97df94b4ffe0b92f5c8a6d2 Mon Sep 17 00:00:00 2001
From: Dylan Hatch <dylanbhatch@google.com>
Date: Tue, 23 Sep 2025 00:49:41 +0000
Subject: objtool: Fix standalone --hacks=jump_label

The objtool command line 'objtool --hacks=jump_label foo.o' on its own
should be expected to rewrite jump labels to NOPs. This means the
add_special_section_alts() code path needs to run when only this option
is provided.

This is mainly relevant in certain debugging situations, but could
potentially also fix kernel builds in which objtool is run with
--hacks=jump_label but without --orc, --stackval, --uaccess, or
--hacks=noinstr.

Fixes: de6fbcedf5ab ("objtool: Read special sections with alts only when specific options are selected")
Signed-off-by: Dylan Hatch <dylanbhatch@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a5770570b106..b0e6479154ee 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2563,7 +2563,8 @@ static int decode_sections(struct objtool_file *file)
 	 * Must be before add_jump_destinations(), which depends on 'func'
 	 * being set for alternatives, to enable proper sibling call detection.
 	 */
-	if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr) {
+	if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr ||
+	    opts.hack_jump_label) {
 		ret = add_special_section_alts(file);
 		if (ret)
 			return ret;
-- 
cgit v1.2.3


From 9b7eacac22693d9177402c9d63e1c1747653d28c Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:19 -0700
Subject: interval_tree: Sync interval_tree_generic.h with tools

The following commit made an improvement to interval_tree_generic.h, but
didn't sync it to the tools copy:

  19811285784f ("lib/interval_tree: skip the check before go to the right subtree")

Sync it, and add it to objtool's sync-check.sh so they are more likely
to stay in sync going forward.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/sync-check.sh | 1 +
 1 file changed, 1 insertion(+)

(limited to 'tools/objtool')

diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh
index 81d120d05442..86d64e3ac6f7 100755
--- a/tools/objtool/sync-check.sh
+++ b/tools/objtool/sync-check.sh
@@ -16,6 +16,7 @@ arch/x86/include/asm/orc_types.h
 arch/x86/include/asm/emulate_prefix.h
 arch/x86/lib/x86-opcode-map.txt
 arch/x86/tools/gen-insn-attr-x86.awk
+include/linux/interval_tree_generic.h
 include/linux/static_call_types.h
 "
 
-- 
cgit v1.2.3


From 07e1c3fd86d7a2ddce3ebc6b7390590c8524a484 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:21 -0700
Subject: objtool: Make find_symbol_containing() less arbitrary

In the rare case of overlapping symbols, find_symbol_containing() just
returns the first one it finds.  Make it slightly less arbitrary by
returning the smallest symbol with size > 0.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index ca5d77db692a..1c1bb2cb960d 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -193,14 +193,29 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
 struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset)
 {
 	struct rb_root_cached *tree = (struct rb_root_cached *)&sec->symbol_tree;
-	struct symbol *iter;
+	struct symbol *sym = NULL, *tmp;
 
-	__sym_for_each(iter, tree, offset, offset) {
-		if (iter->type != STT_SECTION)
-			return iter;
+	__sym_for_each(tmp, tree, offset, offset) {
+		if (tmp->len) {
+			if (!sym) {
+				sym = tmp;
+				continue;
+			}
+
+			if (sym->offset != tmp->offset || sym->len != tmp->len) {
+				/*
+				 * In the rare case of overlapping symbols,
+				 * pick the smaller one.
+				 *
+				 * TODO: outlaw overlapping symbols
+				 */
+				if (tmp->len < sym->len)
+					sym = tmp;
+			}
+		}
 	}
 
-	return NULL;
+	return sym;
 }
 
 /*
-- 
cgit v1.2.3


From 9ebb662fab38a5942100e597b48de5ec9d5e714d Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:22 -0700
Subject: objtool: Fix broken error handling in read_symbols()

The free(sym) call in the read_symbols() error path is fundamentally
broken: 'sym' doesn't point to any allocated block.  If triggered,
things would go from bad to worse.

Remove the free() and simplify the error paths.  Freeing memory isn't
necessary here anyway, these are fatal errors which lead to an immediate
exit().

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 1c1bb2cb960d..b009d9feed76 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -492,14 +492,14 @@ static int read_symbols(struct elf *elf)
 		if (!gelf_getsymshndx(symtab->data, shndx_data, i, &sym->sym,
 				      &shndx)) {
 			ERROR_ELF("gelf_getsymshndx");
-			goto err;
+			return -1;
 		}
 
 		sym->name = elf_strptr(elf->elf, symtab->sh.sh_link,
 				       sym->sym.st_name);
 		if (!sym->name) {
 			ERROR_ELF("elf_strptr");
-			goto err;
+			return -1;
 		}
 
 		if ((sym->sym.st_shndx > SHN_UNDEF &&
@@ -511,7 +511,7 @@ static int read_symbols(struct elf *elf)
 			sym->sec = find_section_by_index(elf, shndx);
 			if (!sym->sec) {
 				ERROR("couldn't find section for symbol %s", sym->name);
-				goto err;
+				return -1;
 			}
 			if (GELF_ST_TYPE(sym->sym.st_info) == STT_SECTION) {
 				sym->name = sym->sec->name;
@@ -581,10 +581,6 @@ static int read_symbols(struct elf *elf)
 	}
 
 	return 0;
-
-err:
-	free(sym);
-	return -1;
 }
 
 static int mark_group_syms(struct elf *elf)
-- 
cgit v1.2.3


From 2bb23cbf3f21919ba17cf63404ec0224bd8bf4fb Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:23 -0700
Subject: objtool: Propagate elf_truncate_section() error in elf_write()

Properly check and propagate the return value of elf_truncate_section()
to avoid silent failures.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index b009d9feed76..19e249f4783c 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -1307,7 +1307,6 @@ static int elf_truncate_section(struct elf *elf, struct section *sec)
 	for (;;) {
 		/* get next data descriptor for the relevant section */
 		data = elf_getdata(s, data);
-
 		if (!data) {
 			if (size) {
 				ERROR("end of section data but non-zero size left\n");
@@ -1343,8 +1342,8 @@ int elf_write(struct elf *elf)
 
 	/* Update changed relocation sections and section headers: */
 	list_for_each_entry(sec, &elf->sections, list) {
-		if (sec->truncate)
-			elf_truncate_section(elf, sec);
+		if (sec->truncate && elf_truncate_section(elf, sec))
+			return -1;
 
 		if (sec_changed(sec)) {
 			s = elf_getscn(elf->elf, sec->idx);
-- 
cgit v1.2.3


From 4ac2ba35f62d330dfb2f3148cc7405a6ce5dfa2d Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:24 -0700
Subject: objtool: Remove error handling boilerplate

Up to a certain point in objtool's execution, all errors are fatal and
return -1.  When propagating such errors, just return -1 directly
instead of trying to propagate the original return code.  This helps
make the code more compact and the behavior more explicit.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c   | 151 ++++++++++++++++++------------------------------
 tools/objtool/special.c |   9 +--
 2 files changed, 59 insertions(+), 101 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b0e6479154ee..02c3e2de85ce 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -430,7 +430,6 @@ static int decode_instructions(struct objtool_file *file)
 	struct symbol *func;
 	unsigned long offset;
 	struct instruction *insn;
-	int ret;
 
 	for_each_sec(file, sec) {
 		struct instruction *insns = NULL;
@@ -479,11 +478,8 @@ static int decode_instructions(struct objtool_file *file)
 			insn->offset = offset;
 			insn->prev_len = prev_len;
 
-			ret = arch_decode_instruction(file, sec, offset,
-						      sec->sh.sh_size - offset,
-						      insn);
-			if (ret)
-				return ret;
+			if (arch_decode_instruction(file, sec, offset, sec->sh.sh_size - offset, insn))
+				return -1;
 
 			prev_len = insn->len;
 
@@ -599,7 +595,7 @@ static int init_pv_ops(struct objtool_file *file)
 	};
 	const char *pv_ops;
 	struct symbol *sym;
-	int idx, nr, ret;
+	int idx, nr;
 
 	if (!opts.noinstr)
 		return 0;
@@ -621,9 +617,8 @@ static int init_pv_ops(struct objtool_file *file)
 		INIT_LIST_HEAD(&file->pv_ops[idx].targets);
 
 	for (idx = 0; (pv_ops = pv_ops_tables[idx]); idx++) {
-		ret = add_pv_ops(file, pv_ops);
-		if (ret)
-			return ret;
+		if (add_pv_ops(file, pv_ops))
+			return -1;
 	}
 
 	return 0;
@@ -1484,7 +1479,6 @@ static int add_jump_destinations(struct objtool_file *file)
 	struct reloc *reloc;
 	struct section *dest_sec;
 	unsigned long dest_off;
-	int ret;
 
 	for_each_insn(file, insn) {
 		struct symbol *func = insn_func(insn);
@@ -1507,9 +1501,8 @@ static int add_jump_destinations(struct objtool_file *file)
 			dest_sec = reloc->sym->sec;
 			dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
 		} else if (reloc->sym->retpoline_thunk) {
-			ret = add_retpoline_call(file, insn);
-			if (ret)
-				return ret;
+			if (add_retpoline_call(file, insn))
+				return -1;
 			continue;
 		} else if (reloc->sym->return_thunk) {
 			add_return_call(file, insn, true);
@@ -1519,9 +1512,8 @@ static int add_jump_destinations(struct objtool_file *file)
 			 * External sibling call or internal sibling call with
 			 * STT_FUNC reloc.
 			 */
-			ret = add_call_dest(file, insn, reloc->sym, true);
-			if (ret)
-				return ret;
+			if (add_call_dest(file, insn, reloc->sym, true))
+				return -1;
 			continue;
 		} else if (reloc->sym->sec->idx) {
 			dest_sec = reloc->sym->sec;
@@ -1570,9 +1562,8 @@ static int add_jump_destinations(struct objtool_file *file)
 		 */
 		if (jump_dest->sym && jump_dest->offset == jump_dest->sym->offset) {
 			if (jump_dest->sym->retpoline_thunk) {
-				ret = add_retpoline_call(file, insn);
-				if (ret)
-					return ret;
+				if (add_retpoline_call(file, insn))
+					return -1;
 				continue;
 			}
 			if (jump_dest->sym->return_thunk) {
@@ -1613,9 +1604,8 @@ static int add_jump_destinations(struct objtool_file *file)
 			 * Internal sibling call without reloc or with
 			 * STT_SECTION reloc.
 			 */
-			ret = add_call_dest(file, insn, insn_func(jump_dest), true);
-			if (ret)
-				return ret;
+			if (add_call_dest(file, insn, insn_func(jump_dest), true))
+				return -1;
 			continue;
 		}
 
@@ -1645,7 +1635,6 @@ static int add_call_destinations(struct objtool_file *file)
 	unsigned long dest_off;
 	struct symbol *dest;
 	struct reloc *reloc;
-	int ret;
 
 	for_each_insn(file, insn) {
 		struct symbol *func = insn_func(insn);
@@ -1657,9 +1646,8 @@ static int add_call_destinations(struct objtool_file *file)
 			dest_off = arch_jump_destination(insn);
 			dest = find_call_destination(insn->sec, dest_off);
 
-			ret = add_call_dest(file, insn, dest, false);
-			if (ret)
-				return ret;
+			if (add_call_dest(file, insn, dest, false))
+				return -1;
 
 			if (func && func->ignore)
 				continue;
@@ -1683,19 +1671,16 @@ static int add_call_destinations(struct objtool_file *file)
 				return -1;
 			}
 
-			ret = add_call_dest(file, insn, dest, false);
-			if (ret)
-				return ret;
+			if (add_call_dest(file, insn, dest, false))
+				return -1;
 
 		} else if (reloc->sym->retpoline_thunk) {
-			ret = add_retpoline_call(file, insn);
-			if (ret)
-				return ret;
+			if (add_retpoline_call(file, insn))
+				return -1;
 
 		} else {
-			ret = add_call_dest(file, insn, reloc->sym, false);
-			if (ret)
-				return ret;
+			if (add_call_dest(file, insn, reloc->sym, false))
+				return -1;
 		}
 	}
 
@@ -1912,7 +1897,6 @@ static int add_special_section_alts(struct objtool_file *file)
 	struct instruction *orig_insn, *new_insn;
 	struct special_alt *special_alt, *tmp;
 	struct alternative *alt;
-	int ret;
 
 	if (special_get_alts(file->elf, &special_alts))
 		return -1;
@@ -1944,16 +1928,12 @@ static int add_special_section_alts(struct objtool_file *file)
 				continue;
 			}
 
-			ret = handle_group_alt(file, special_alt, orig_insn,
-					       &new_insn);
-			if (ret)
-				return ret;
+			if (handle_group_alt(file, special_alt, orig_insn, &new_insn))
+				return -1;
 
 		} else if (special_alt->jump_or_nop) {
-			ret = handle_jump_alt(file, special_alt, orig_insn,
-					      &new_insn);
-			if (ret)
-				return ret;
+			if (handle_jump_alt(file, special_alt, orig_insn, &new_insn))
+				return -1;
 		}
 
 		alt = calloc(1, sizeof(*alt));
@@ -2141,15 +2121,13 @@ static int add_func_jump_tables(struct objtool_file *file,
 				  struct symbol *func)
 {
 	struct instruction *insn;
-	int ret;
 
 	func_for_each_insn(file, func, insn) {
 		if (!insn_jump_table(insn))
 			continue;
 
-		ret = add_jump_table(file, insn);
-		if (ret)
-			return ret;
+		if (add_jump_table(file, insn))
+			return -1;
 	}
 
 	return 0;
@@ -2163,7 +2141,6 @@ static int add_func_jump_tables(struct objtool_file *file,
 static int add_jump_table_alts(struct objtool_file *file)
 {
 	struct symbol *func;
-	int ret;
 
 	if (!file->rodata)
 		return 0;
@@ -2173,9 +2150,8 @@ static int add_jump_table_alts(struct objtool_file *file)
 			continue;
 
 		mark_func_jump_tables(file, func);
-		ret = add_func_jump_tables(file, func);
-		if (ret)
-			return ret;
+		if (add_func_jump_tables(file, func))
+			return -1;
 	}
 
 	return 0;
@@ -2299,7 +2275,7 @@ static int read_annotate(struct objtool_file *file,
 	struct instruction *insn;
 	struct reloc *reloc;
 	uint64_t offset;
-	int type, ret;
+	int type;
 
 	sec = find_section_by_name(file->elf, ".discard.annotate_insn");
 	if (!sec)
@@ -2329,9 +2305,8 @@ static int read_annotate(struct objtool_file *file,
 			return -1;
 		}
 
-		ret = func(file, type, insn);
-		if (ret < 0)
-			return ret;
+		if (func(file, type, insn))
+			return -1;
 	}
 
 	return 0;
@@ -2530,34 +2505,27 @@ static void mark_rodata(struct objtool_file *file)
 
 static int decode_sections(struct objtool_file *file)
 {
-	int ret;
-
 	mark_rodata(file);
 
-	ret = init_pv_ops(file);
-	if (ret)
-		return ret;
+	if (init_pv_ops(file))
+		return -1;
 
 	/*
 	 * Must be before add_{jump_call}_destination.
 	 */
-	ret = classify_symbols(file);
-	if (ret)
-		return ret;
+	if (classify_symbols(file))
+		return -1;
 
-	ret = decode_instructions(file);
-	if (ret)
-		return ret;
+	if (decode_instructions(file))
+		return -1;
 
-	ret = add_ignores(file);
-	if (ret)
-		return ret;
+	if (add_ignores(file))
+		return -1;
 
 	add_uaccess_safe(file);
 
-	ret = read_annotate(file, __annotate_early);
-	if (ret)
-		return ret;
+	if (read_annotate(file, __annotate_early))
+		return -1;
 
 	/*
 	 * Must be before add_jump_destinations(), which depends on 'func'
@@ -2565,42 +2533,35 @@ static int decode_sections(struct objtool_file *file)
 	 */
 	if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr ||
 	    opts.hack_jump_label) {
-		ret = add_special_section_alts(file);
-		if (ret)
-			return ret;
+		if (add_special_section_alts(file))
+			return -1;
 	}
 
-	ret = add_jump_destinations(file);
-	if (ret)
-		return ret;
+	if (add_jump_destinations(file))
+		return -1;
 
 	/*
 	 * Must be before add_call_destination(); it changes INSN_CALL to
 	 * INSN_JUMP.
 	 */
-	ret = read_annotate(file, __annotate_ifc);
-	if (ret)
-		return ret;
+	if (read_annotate(file, __annotate_ifc))
+		return -1;
 
-	ret = add_call_destinations(file);
-	if (ret)
-		return ret;
+	if (add_call_destinations(file))
+		return -1;
 
-	ret = add_jump_table_alts(file);
-	if (ret)
-		return ret;
+	if (add_jump_table_alts(file))
+		return -1;
 
-	ret = read_unwind_hints(file);
-	if (ret)
-		return ret;
+	if (read_unwind_hints(file))
+		return -1;
 
 	/*
 	 * Must be after add_call_destinations() such that it can override
 	 * dead_end_function() marks.
 	 */
-	ret = read_annotate(file, __annotate_late);
-	if (ret)
-		return ret;
+	if (read_annotate(file, __annotate_late))
+		return -1;
 
 	return 0;
 }
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index c80fed8a840e..c0beefb93b62 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -133,7 +133,7 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
 	struct section *sec;
 	unsigned int nr_entries;
 	struct special_alt *alt;
-	int idx, ret;
+	int idx;
 
 	INIT_LIST_HEAD(alts);
 
@@ -157,11 +157,8 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
 			}
 			memset(alt, 0, sizeof(*alt));
 
-			ret = get_alt_entry(elf, entry, sec, idx, alt);
-			if (ret > 0)
-				continue;
-			if (ret < 0)
-				return ret;
+			if (get_alt_entry(elf, entry, sec, idx, alt))
+				return -1;
 
 			list_add_tail(&alt->list, alts);
 		}
-- 
cgit v1.2.3


From 81cf39be3559f3cebef6ad7b0893c06bf5a5847e Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:25 -0700
Subject: objtool: Add empty symbols to the symbol tree again

The following commit

  5da6aea375cd ("objtool: Fix find_{symbol,func}_containing()")

fixed the issue where overlapping symbols weren't getting sorted
properly in the symbol tree.  Therefore the workaround to skip adding
empty symbols from the following commit

  a2e38dffcd93 ("objtool: Don't add empty symbols to the rbtree")

is no longer needed.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 19e249f4783c..a8a78b55d3ec 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -96,7 +96,8 @@ static inline unsigned long __sym_last(struct symbol *s)
 }
 
 INTERVAL_TREE_DEFINE(struct symbol, node, unsigned long, __subtree_last,
-		     __sym_start, __sym_last, static, __sym)
+		     __sym_start, __sym_last, static inline __maybe_unused,
+		     __sym)
 
 #define __sym_for_each(_iter, _tree, _start, _end)			\
 	for (_iter = __sym_iter_first((_tree), (_start), (_end));	\
@@ -440,13 +441,6 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
 	list_add(&sym->list, entry);
 	elf_hash_add(symbol, &sym->hash, sym->idx);
 	elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
-
-	/*
-	 * Don't store empty STT_NOTYPE symbols in the rbtree.  They
-	 * can exist within a function, confusing the sorting.
-	 */
-	if (!sym->len)
-		__sym_remove(sym, &sym->sec->symbol_tree);
 }
 
 static int read_symbols(struct elf *elf)
-- 
cgit v1.2.3


From c2a3e7af31107a2e1dff92b0601d525466dc21b7 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:26 -0700
Subject: objtool: Fix interval tree insertion for zero-length symbols

Zero-length symbols get inserted in the wrong spot.  Fix that.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index a8a78b55d3ec..c024937eb12a 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -92,7 +92,7 @@ static inline unsigned long __sym_start(struct symbol *s)
 
 static inline unsigned long __sym_last(struct symbol *s)
 {
-	return s->offset + s->len - 1;
+	return s->offset + (s->len ? s->len - 1 : 0);
 }
 
 INTERVAL_TREE_DEFINE(struct symbol, node, unsigned long, __subtree_last,
-- 
cgit v1.2.3


From 72567c630d32bc31f671977f78228c80937ed80e Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:27 -0700
Subject: objtool: Fix weak symbol detection

find_symbol_hole_containing() fails to find a symbol hole (aka stripped
weak symbol) if its section has no symbols before the hole.  This breaks
weak symbol detection if -ffunction-sections is enabled.

Fix that by allowing the interval tree to contain section symbols, which
are always at offset zero for a given section.

Fixes a bunch of (-ffunction-sections) warnings like:

  vmlinux.o: warning: objtool: .text.__x64_sys_io_setup+0x10: unreachable instruction

Fixes: 4adb23686795 ("objtool: Ignore extra-symbol code")
Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index c024937eb12a..d7fb3d0b05cf 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -109,7 +109,7 @@ struct symbol_hole {
 };
 
 /*
- * Find !section symbol where @offset is after it.
+ * Find the last symbol before @offset.
  */
 static int symbol_hole_by_offset(const void *key, const struct rb_node *node)
 {
@@ -120,8 +120,7 @@ static int symbol_hole_by_offset(const void *key, const struct rb_node *node)
 		return -1;
 
 	if (sh->key >= s->offset + s->len) {
-		if (s->type != STT_SECTION)
-			sh->sym = s;
+		sh->sym = s;
 		return 1;
 	}
 
@@ -428,7 +427,8 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
 	sym->len = sym->sym.st_size;
 
 	__sym_for_each(iter, &sym->sec->symbol_tree, sym->offset, sym->offset) {
-		if (iter->offset == sym->offset && iter->type == sym->type)
+		if (iter->offset == sym->offset && iter->type == sym->type &&
+		    iter->len == sym->len)
 			iter->alias = sym;
 	}
 
-- 
cgit v1.2.3


From 41d24d78589705f85cbe90e5a8c1b55ea05557a2 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:28 -0700
Subject: objtool: Fix x86 addend calculation

On x86, arch_dest_reloc_offset() hardcodes the addend adjustment to
four, but the actual adjustment depends on the relocation type.  Fix
that.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/arch/loongarch/decode.c |  4 ++--
 tools/objtool/arch/powerpc/decode.c   |  4 ++--
 tools/objtool/arch/x86/decode.c       |  9 +++++++--
 tools/objtool/check.c                 | 15 +++++----------
 tools/objtool/include/objtool/arch.h  |  2 +-
 5 files changed, 17 insertions(+), 17 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index 2e555c4060c5..77942b927a7a 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -17,9 +17,9 @@ unsigned long arch_jump_destination(struct instruction *insn)
 	return insn->offset + (insn->immediate << 2);
 }
 
-unsigned long arch_dest_reloc_offset(int addend)
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
 {
-	return addend;
+	return reloc_addend(reloc);
 }
 
 bool arch_pc_relative_reloc(struct reloc *reloc)
diff --git a/tools/objtool/arch/powerpc/decode.c b/tools/objtool/arch/powerpc/decode.c
index c851c51d4bd3..9b17885e6cba 100644
--- a/tools/objtool/arch/powerpc/decode.c
+++ b/tools/objtool/arch/powerpc/decode.c
@@ -14,9 +14,9 @@ int arch_ftrace_match(char *name)
 	return !strcmp(name, "_mcount");
 }
 
-unsigned long arch_dest_reloc_offset(int addend)
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
 {
-	return addend;
+	return reloc_addend(reloc);
 }
 
 bool arch_callee_saved_reg(unsigned char reg)
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 0ad5cc70ecbe..6742002a01f5 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -68,9 +68,14 @@ bool arch_callee_saved_reg(unsigned char reg)
 	}
 }
 
-unsigned long arch_dest_reloc_offset(int addend)
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
 {
-	return addend + 4;
+	s64 addend = reloc_addend(reloc);
+
+	if (arch_pc_relative_reloc(reloc))
+		addend += insn->offset + insn->len - reloc_offset(reloc);
+
+	return addend;
 }
 
 unsigned long arch_jump_destination(struct instruction *insn)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 02c3e2de85ce..65eb90034d3e 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1499,7 +1499,7 @@ static int add_jump_destinations(struct objtool_file *file)
 			dest_off = arch_jump_destination(insn);
 		} else if (reloc->sym->type == STT_SECTION) {
 			dest_sec = reloc->sym->sec;
-			dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
+			dest_off = arch_insn_adjusted_addend(insn, reloc);
 		} else if (reloc->sym->retpoline_thunk) {
 			if (add_retpoline_call(file, insn))
 				return -1;
@@ -1518,7 +1518,7 @@ static int add_jump_destinations(struct objtool_file *file)
 		} else if (reloc->sym->sec->idx) {
 			dest_sec = reloc->sym->sec;
 			dest_off = reloc->sym->sym.st_value +
-				   arch_dest_reloc_offset(reloc_addend(reloc));
+				   arch_insn_adjusted_addend(insn, reloc);
 		} else {
 			/* non-func asm code jumping to another file */
 			continue;
@@ -1663,7 +1663,7 @@ static int add_call_destinations(struct objtool_file *file)
 			}
 
 		} else if (reloc->sym->type == STT_SECTION) {
-			dest_off = arch_dest_reloc_offset(reloc_addend(reloc));
+			dest_off = arch_insn_adjusted_addend(insn, reloc);
 			dest = find_call_destination(reloc->sym->sec, dest_off);
 			if (!dest) {
 				ERROR_INSN(insn, "can't find call dest symbol at %s+0x%lx",
@@ -3315,7 +3315,7 @@ static bool pv_call_dest(struct objtool_file *file, struct instruction *insn)
 	if (!reloc || strcmp(reloc->sym->name, "pv_ops"))
 		return false;
 
-	idx = (arch_dest_reloc_offset(reloc_addend(reloc)) / sizeof(void *));
+	idx = arch_insn_adjusted_addend(insn, reloc) / sizeof(void *);
 
 	if (file->pv_ops[idx].clean)
 		return true;
@@ -4396,12 +4396,7 @@ static int validate_ibt_insn(struct objtool_file *file, struct instruction *insn
 					      reloc_offset(reloc) + 1,
 					      (insn->offset + insn->len) - (reloc_offset(reloc) + 1))) {
 
-		off = reloc->sym->offset;
-		if (reloc_type(reloc) == R_X86_64_PC32 ||
-		    reloc_type(reloc) == R_X86_64_PLT32)
-			off += arch_dest_reloc_offset(reloc_addend(reloc));
-		else
-			off += reloc_addend(reloc);
+		off = reloc->sym->offset + arch_insn_adjusted_addend(insn, reloc);
 
 		dest = find_insn(file, reloc->sym->sec, off);
 		if (!dest)
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index be33c7b43180..68664625a467 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -83,7 +83,7 @@ bool arch_callee_saved_reg(unsigned char reg);
 
 unsigned long arch_jump_destination(struct instruction *insn);
 
-unsigned long arch_dest_reloc_offset(int addend);
+s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc);
 
 const char *arch_nop_insn(int len);
 const char *arch_ret_insn(int len);
-- 
cgit v1.2.3


From 68245893cf447cca478e6bd71c02741656053ef4 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:29 -0700
Subject: objtool: Fix __pa_symbol() relocation handling

__pa_symbol() generates a relocation which refers to a physical address.
Convert it to back its virtual form before calculating the addend.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/arch/x86/decode.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 6742002a01f5..b10200cc50c9 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -68,6 +68,17 @@ bool arch_callee_saved_reg(unsigned char reg)
 	}
 }
 
+/* Undo the effects of __pa_symbol() if necessary */
+static unsigned long phys_to_virt(unsigned long pa)
+{
+	s64 va = pa;
+
+	if (va > 0)
+		va &= ~(0x80000000);
+
+	return va;
+}
+
 s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
 {
 	s64 addend = reloc_addend(reloc);
@@ -75,7 +86,7 @@ s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
 	if (arch_pc_relative_reloc(reloc))
 		addend += insn->offset + insn->len - reloc_offset(reloc);
 
-	return addend;
+	return phys_to_virt(addend);
 }
 
 unsigned long arch_jump_destination(struct instruction *insn)
-- 
cgit v1.2.3


From 4cdee7888f42f5573b380ddfa9da43208e759bdc Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:30 -0700
Subject: objtool: Fix "unexpected end of section" warning for alternatives

Due to the short circuiting logic in next_insn_to_validate(), control
flow may silently transition from .altinstr_replacement to .text without
a corresponding nested call to validate_branch().

As a result the validate_branch() 'sec' variable doesn't get
reinitialized, which can trigger a confusing "unexpected end of section"
warning which blames .altinstr_replacement rather than the offending
fallthrough function.

Fix that by not caching the section.  There's no point in doing that
anyway.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 65eb90034d3e..c2e46f901a53 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3512,15 +3512,12 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 {
 	struct alternative *alt;
 	struct instruction *next_insn, *prev_insn = NULL;
-	struct section *sec;
 	u8 visited;
 	int ret;
 
 	if (func && func->ignore)
 		return 0;
 
-	sec = insn->sec;
-
 	while (1) {
 		next_insn = next_insn_to_validate(file, insn);
 
@@ -3760,7 +3757,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 
 			WARN("%s%sunexpected end of section %s",
 			     func ? func->name : "", func ? "(): " : "",
-			     sec->name);
+			     insn->sec->name);
 			return 1;
 		}
 
-- 
cgit v1.2.3


From 3e4b5f66cf1a7879a081f5044ff1796aa33cb999 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:31 -0700
Subject: objtool: Check for missing annotation entries in read_annotate()

Add a sanity check to make sure none of the relocations for the
.discard.annotate_insn section have gone missing.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c2e46f901a53..49d2db7c7f5b 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2293,6 +2293,11 @@ static int read_annotate(struct objtool_file *file,
 		sec->sh.sh_entsize = 8;
 	}
 
+	if (sec_num_entries(sec) != sec_num_entries(sec->rsec)) {
+		ERROR("bad .discard.annotate_insn section: missing relocs");
+		return -1;
+	}
+
 	for_each_reloc(sec->rsec, reloc) {
 		type = *(u32 *)(sec->data->d_buf + (reloc_idx(reloc) * sec->sh.sh_entsize) + 4);
 		type = bswap_if_needed(file->elf, type);
-- 
cgit v1.2.3


From 34244f784c6d062af184944a25f40ab50dfdb67a Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:32 -0700
Subject: objtool: Const string cleanup

Use 'const char *' where applicable.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/arch/loongarch/decode.c | 2 +-
 tools/objtool/arch/powerpc/decode.c   | 2 +-
 tools/objtool/arch/x86/decode.c       | 2 +-
 tools/objtool/elf.c                   | 6 +++---
 tools/objtool/include/objtool/arch.h  | 2 +-
 tools/objtool/include/objtool/elf.h   | 6 +++---
 6 files changed, 10 insertions(+), 10 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index 77942b927a7a..0115b97c526b 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -7,7 +7,7 @@
 #include <linux/objtool_types.h>
 #include <arch/elf.h>
 
-int arch_ftrace_match(char *name)
+int arch_ftrace_match(const char *name)
 {
 	return !strcmp(name, "_mcount");
 }
diff --git a/tools/objtool/arch/powerpc/decode.c b/tools/objtool/arch/powerpc/decode.c
index 9b17885e6cba..d4cb02120a6b 100644
--- a/tools/objtool/arch/powerpc/decode.c
+++ b/tools/objtool/arch/powerpc/decode.c
@@ -9,7 +9,7 @@
 #include <objtool/builtin.h>
 #include <objtool/endianness.h>
 
-int arch_ftrace_match(char *name)
+int arch_ftrace_match(const char *name)
 {
 	return !strcmp(name, "_mcount");
 }
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index b10200cc50c9..6bb46d998153 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -23,7 +23,7 @@
 #include <objtool/builtin.h>
 #include <arch/elf.h>
 
-int arch_ftrace_match(char *name)
+int arch_ftrace_match(const char *name)
 {
 	return !strcmp(name, "__fentry__");
 }
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index d7fb3d0b05cf..2ea6d591c3c2 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -853,7 +853,7 @@ elf_create_section_symbol(struct elf *elf, struct section *sec)
 	return sym;
 }
 
-static int elf_add_string(struct elf *elf, struct section *strtab, char *str);
+static int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
 
 struct symbol *
 elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size)
@@ -1086,7 +1086,7 @@ err:
 	return NULL;
 }
 
-static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
+static int elf_add_string(struct elf *elf, struct section *strtab, const char *str)
 {
 	Elf_Data *data;
 	Elf_Scn *s;
@@ -1111,7 +1111,7 @@ static int elf_add_string(struct elf *elf, struct section *strtab, char *str)
 		return -1;
 	}
 
-	data->d_buf = str;
+	data->d_buf = strdup(str);
 	data->d_size = strlen(str) + 1;
 	data->d_align = 1;
 
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index 68664625a467..a4502947307a 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -71,7 +71,7 @@ struct stack_op {
 
 struct instruction;
 
-int arch_ftrace_match(char *name);
+int arch_ftrace_match(const char *name);
 
 void arch_initial_func_cfi_state(struct cfi_init_state *state);
 
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index df8434d3b744..74ce454790f4 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -40,7 +40,7 @@ struct section {
 	struct section *base, *rsec;
 	struct symbol *sym;
 	Elf_Data *data;
-	char *name;
+	const char *name;
 	int idx;
 	bool _changed, text, rodata, noinstr, init, truncate;
 	struct reloc *relocs;
@@ -53,7 +53,7 @@ struct symbol {
 	struct elf_hash_node name_hash;
 	GElf_Sym sym;
 	struct section *sec;
-	char *name;
+	const char *name;
 	unsigned int idx, len;
 	unsigned long offset;
 	unsigned long __subtree_last;
@@ -88,7 +88,7 @@ struct elf {
 	GElf_Ehdr ehdr;
 	int fd;
 	bool changed;
-	char *name;
+	const char *name;
 	unsigned int num_files;
 	struct list_head sections;
 	unsigned long num_relocs;
-- 
cgit v1.2.3


From 31eca25f3a3b0de960ca9a478e5a4b2d0b2e8558 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:33 -0700
Subject: objtool: Clean up compiler flag usage

KBUILD_HOSTCFLAGS and KBUILD_HOSTLDFLAGS aren't defined when objtool is
built standalone.  Also, the EXTRA_WARNINGS flags are rather arbitrary.

Make things simpler and more consistent by specifying compiler flags
explicitly and tweaking the warnings.  Also make a few code tweaks to
make the new warnings happy.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/Makefile | 15 ++++++++++-----
 tools/objtool/check.c  |  4 ++--
 tools/objtool/elf.c    |  2 +-
 3 files changed, 13 insertions(+), 8 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 8c20361dd100..fc82d47f2b9a 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -23,6 +23,11 @@ LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lel
 
 all: $(OBJTOOL)
 
+WARNINGS := -Werror -Wall -Wextra -Wmissing-prototypes			\
+	    -Wmissing-declarations -Wwrite-strings			\
+	    -Wno-implicit-fallthrough -Wno-sign-compare			\
+	    -Wno-unused-parameter
+
 INCLUDES := -I$(srctree)/tools/include \
 	    -I$(srctree)/tools/include/uapi \
 	    -I$(srctree)/tools/arch/$(HOSTARCH)/include/uapi \
@@ -30,11 +35,11 @@ INCLUDES := -I$(srctree)/tools/include \
 	    -I$(srctree)/tools/objtool/include \
 	    -I$(srctree)/tools/objtool/arch/$(SRCARCH)/include \
 	    -I$(LIBSUBCMD_OUTPUT)/include
-# Note, EXTRA_WARNINGS here was determined for CC and not HOSTCC, it
-# is passed here to match a legacy behavior.
-WARNINGS := $(EXTRA_WARNINGS) -Wno-switch-default -Wno-switch-enum -Wno-packed -Wno-nested-externs
-OBJTOOL_CFLAGS := -Werror $(WARNINGS) $(KBUILD_HOSTCFLAGS) -g $(INCLUDES) $(LIBELF_FLAGS)
-OBJTOOL_LDFLAGS := $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
+
+OBJTOOL_CFLAGS  := -std=gnu11 -fomit-frame-pointer -O2 -g \
+		   $(WARNINGS) $(INCLUDES) $(LIBELF_FLAGS) $(HOSTCFLAGS)
+
+OBJTOOL_LDFLAGS := $(LIBSUBCMD) $(LIBELF_LIBS) $(HOSTLDFLAGS)
 
 # Allow old libelf to be used:
 elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - 2>/dev/null | grep elf_getshdr)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 49d2db7c7f5b..2bd35d11411b 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -461,7 +461,7 @@ static int decode_instructions(struct objtool_file *file)
 
 		for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
 			if (!insns || idx == INSN_CHUNK_MAX) {
-				insns = calloc(sizeof(*insn), INSN_CHUNK_SIZE);
+				insns = calloc(INSN_CHUNK_SIZE, sizeof(*insn));
 				if (!insns) {
 					ERROR_GLIBC("calloc");
 					return -1;
@@ -607,7 +607,7 @@ static int init_pv_ops(struct objtool_file *file)
 		return 0;
 
 	nr = sym->len / sizeof(unsigned long);
-	file->pv_ops = calloc(sizeof(struct pv_state), nr);
+	file->pv_ops = calloc(nr, sizeof(struct pv_state));
 	if (!file->pv_ops) {
 		ERROR_GLIBC("calloc");
 		return -1;
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 2ea6d591c3c2..c27edeed2dd0 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -736,7 +736,7 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
 	}
 
 	/* setup extended section index magic and write the symbol */
-	if ((shndx >= SHN_UNDEF && shndx < SHN_LORESERVE) || is_special_shndx) {
+	if (shndx < SHN_LORESERVE || is_special_shndx) {
 		sym->sym.st_shndx = shndx;
 		if (!shndx_data)
 			shndx = 0;
-- 
cgit v1.2.3


From 72e4b6b44e9f53990315c6dd9fae2b2fc89c021a Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:34 -0700
Subject: objtool: Remove .parainstructions reference

The .parainstructions section no longer exists since the following
commit:

  60bc276b129e ("x86/paravirt: Switch mixed paravirt/alternative calls to alternatives").

Remove the reference to it.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c | 1 -
 1 file changed, 1 deletion(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 2bd35d11411b..61e071c46ac2 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4468,7 +4468,6 @@ static int validate_ibt(struct objtool_file *file)
 		    !strcmp(sec->name, ".altinstructions")		||
 		    !strcmp(sec->name, ".ibt_endbr_seal")		||
 		    !strcmp(sec->name, ".orc_unwind_ip")		||
-		    !strcmp(sec->name, ".parainstructions")		||
 		    !strcmp(sec->name, ".retpoline_sites")		||
 		    !strcmp(sec->name, ".smp_locks")			||
 		    !strcmp(sec->name, ".static_call_sites")		||
-- 
cgit v1.2.3


From 96eceff331ea535b763b161df01300bbfd93b372 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:35 -0700
Subject: objtool: Convert elf iterator macros to use 'struct elf'

'struct objtool_file' is specific to the check code and doesn't belong
in the elf code which is supposed to be objtool_file-agnostic.  Convert
the elf iterator macros to use 'struct elf' instead.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c               | 24 ++++++++++++------------
 tools/objtool/include/objtool/elf.h |  8 ++++----
 tools/objtool/orc_gen.c             |  2 +-
 3 files changed, 17 insertions(+), 17 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 61e071c46ac2..dbc4fbdb77c4 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -106,7 +106,7 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file,
 #define for_each_insn(file, insn)					\
 	for (struct section *__sec, *__fake = (struct section *)1;	\
 	     __fake; __fake = NULL)					\
-		for_each_sec(file, __sec)				\
+		for_each_sec(file->elf, __sec)				\
 			sec_for_each_insn(file, __sec, insn)
 
 #define func_for_each_insn(file, func, insn)				\
@@ -431,7 +431,7 @@ static int decode_instructions(struct objtool_file *file)
 	unsigned long offset;
 	struct instruction *insn;
 
-	for_each_sec(file, sec) {
+	for_each_sec(file->elf, sec) {
 		struct instruction *insns = NULL;
 		u8 prev_len = 0;
 		u8 idx = 0;
@@ -857,7 +857,7 @@ static int create_cfi_sections(struct objtool_file *file)
 	}
 
 	idx = 0;
-	for_each_sym(file, sym) {
+	for_each_sym(file->elf, sym) {
 		if (sym->type != STT_FUNC)
 			continue;
 
@@ -873,7 +873,7 @@ static int create_cfi_sections(struct objtool_file *file)
 		return -1;
 
 	idx = 0;
-	for_each_sym(file, sym) {
+	for_each_sym(file->elf, sym) {
 		if (sym->type != STT_FUNC)
 			continue;
 
@@ -2145,7 +2145,7 @@ static int add_jump_table_alts(struct objtool_file *file)
 	if (!file->rodata)
 		return 0;
 
-	for_each_sym(file, func) {
+	for_each_sym(file->elf, func) {
 		if (func->type != STT_FUNC)
 			continue;
 
@@ -2451,7 +2451,7 @@ static int classify_symbols(struct objtool_file *file)
 {
 	struct symbol *func;
 
-	for_each_sym(file, func) {
+	for_each_sym(file->elf, func) {
 		if (func->type == STT_NOTYPE && strstarts(func->name, ".L"))
 			func->local_label = true;
 
@@ -2496,7 +2496,7 @@ static void mark_rodata(struct objtool_file *file)
 	 *
 	 * .rodata.str1.* sections are ignored; they don't contain jump tables.
 	 */
-	for_each_sec(file, sec) {
+	for_each_sec(file->elf, sec) {
 		if ((!strncmp(sec->name, ".rodata", 7) &&
 		     !strstr(sec->name, ".str1.")) ||
 		    !strncmp(sec->name, ".data.rel.ro", 12)) {
@@ -4178,7 +4178,7 @@ static int add_prefix_symbols(struct objtool_file *file)
 	struct section *sec;
 	struct symbol *func;
 
-	for_each_sec(file, sec) {
+	for_each_sec(file->elf, sec) {
 		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
 			continue;
 
@@ -4270,7 +4270,7 @@ static int validate_functions(struct objtool_file *file)
 	struct section *sec;
 	int warnings = 0;
 
-	for_each_sec(file, sec) {
+	for_each_sec(file->elf, sec) {
 		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
 			continue;
 
@@ -4449,7 +4449,7 @@ static int validate_ibt(struct objtool_file *file)
 	for_each_insn(file, insn)
 		warnings += validate_ibt_insn(file, insn);
 
-	for_each_sec(file, sec) {
+	for_each_sec(file->elf, sec) {
 
 		/* Already done by validate_ibt_insn() */
 		if (sec->sh.sh_flags & SHF_EXECINSTR)
@@ -4610,7 +4610,7 @@ static void disas_warned_funcs(struct objtool_file *file)
 	struct symbol *sym;
 	char *funcs = NULL, *tmp;
 
-	for_each_sym(file, sym) {
+	for_each_sym(file->elf, sym) {
 		if (sym->warned) {
 			if (!funcs) {
 				funcs = malloc(strlen(sym->name) + 1);
@@ -4650,7 +4650,7 @@ static int check_abs_references(struct objtool_file *file)
 	struct reloc *reloc;
 	int ret = 0;
 
-	for_each_sec(file, sec) {
+	for_each_sec(file->elf, sec) {
 		/* absolute references in non-loadable sections are fine */
 		if (!(sec->sh.sh_flags & SHF_ALLOC))
 			continue;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 74ce454790f4..4d5f27b49724 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -325,16 +325,16 @@ static inline void set_sym_next_reloc(struct reloc *reloc, struct reloc *next)
 	reloc->_sym_next_reloc = (unsigned long)next | bit;
 }
 
-#define for_each_sec(file, sec)						\
-	list_for_each_entry(sec, &file->elf->sections, list)
+#define for_each_sec(elf, sec)						\
+	list_for_each_entry(sec, &elf->sections, list)
 
 #define sec_for_each_sym(sec, sym)					\
 	list_for_each_entry(sym, &sec->symbol_list, list)
 
-#define for_each_sym(file, sym)						\
+#define for_each_sym(elf, sym)						\
 	for (struct section *__sec, *__fake = (struct section *)1;	\
 	     __fake; __fake = NULL)					\
-		for_each_sec(file, __sec)				\
+		for_each_sec(elf, __sec)				\
 			sec_for_each_sym(__sec, sym)
 
 #define for_each_reloc(rsec, reloc)					\
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index 922e6aac7cea..6eff3d6a125c 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -57,7 +57,7 @@ int orc_create(struct objtool_file *file)
 
 	/* Build a deduplicated list of ORC entries: */
 	INIT_LIST_HEAD(&orc_list);
-	for_each_sec(file, sec) {
+	for_each_sec(file->elf, sec) {
 		struct orc_entry orc, prev_orc = {0};
 		struct instruction *insn;
 		bool empty = true;
-- 
cgit v1.2.3


From 25eac74b6bdbf6d15911b582e747e8ad12fcbf8f Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:36 -0700
Subject: objtool: Add section/symbol type helpers

Add some helper macros to improve readability.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/arch/x86/special.c    |  2 +-
 tools/objtool/check.c               | 58 ++++++++++++++++----------------
 tools/objtool/elf.c                 | 20 +++++------
 tools/objtool/include/objtool/elf.h | 66 +++++++++++++++++++++++++++++++++++++
 tools/objtool/special.c             |  4 +--
 5 files changed, 108 insertions(+), 42 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c
index 06ca4a2659a4..09300761f108 100644
--- a/tools/objtool/arch/x86/special.c
+++ b/tools/objtool/arch/x86/special.c
@@ -89,7 +89,7 @@ struct reloc *arch_find_switch_table(struct objtool_file *file,
 	/* look for a relocation which references .rodata */
 	text_reloc = find_reloc_by_dest_range(file->elf, insn->sec,
 					      insn->offset, insn->len);
-	if (!text_reloc || text_reloc->sym->type != STT_SECTION ||
+	if (!text_reloc || !is_sec_sym(text_reloc->sym) ||
 	    !text_reloc->sym->sec->rodata)
 		return NULL;
 
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index dbc4fbdb77c4..f38f4a2e4e29 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -261,7 +261,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 	if (!func)
 		return false;
 
-	if (func->bind == STB_GLOBAL || func->bind == STB_WEAK) {
+	if (!is_local_sym(func)) {
 		if (is_rust_noreturn(func))
 			return true;
 
@@ -270,7 +270,7 @@ static bool __dead_end_function(struct objtool_file *file, struct symbol *func,
 				return true;
 	}
 
-	if (func->bind == STB_WEAK)
+	if (is_weak_sym(func))
 		return false;
 
 	if (!func->len)
@@ -436,7 +436,7 @@ static int decode_instructions(struct objtool_file *file)
 		u8 prev_len = 0;
 		u8 idx = 0;
 
-		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+		if (!is_text_sec(sec))
 			continue;
 
 		if (strcmp(sec->name, ".altinstr_replacement") &&
@@ -459,7 +459,7 @@ static int decode_instructions(struct objtool_file *file)
 		if (!strcmp(sec->name, ".init.text") && !opts.module)
 			sec->init = true;
 
-		for (offset = 0; offset < sec->sh.sh_size; offset += insn->len) {
+		for (offset = 0; offset < sec_size(sec); offset += insn->len) {
 			if (!insns || idx == INSN_CHUNK_MAX) {
 				insns = calloc(INSN_CHUNK_SIZE, sizeof(*insn));
 				if (!insns) {
@@ -478,7 +478,7 @@ static int decode_instructions(struct objtool_file *file)
 			insn->offset = offset;
 			insn->prev_len = prev_len;
 
-			if (arch_decode_instruction(file, sec, offset, sec->sh.sh_size - offset, insn))
+			if (arch_decode_instruction(file, sec, offset, sec_size(sec) - offset, insn))
 				return -1;
 
 			prev_len = insn->len;
@@ -496,12 +496,12 @@ static int decode_instructions(struct objtool_file *file)
 		}
 
 		sec_for_each_sym(sec, func) {
-			if (func->type != STT_NOTYPE && func->type != STT_FUNC)
+			if (!is_notype_sym(func) && !is_func_sym(func))
 				continue;
 
-			if (func->offset == sec->sh.sh_size) {
+			if (func->offset == sec_size(sec)) {
 				/* Heuristic: likely an "end" symbol */
-				if (func->type == STT_NOTYPE)
+				if (is_notype_sym(func))
 					continue;
 				ERROR("%s(): STT_FUNC at end of section", func->name);
 				return -1;
@@ -517,7 +517,7 @@ static int decode_instructions(struct objtool_file *file)
 
 			sym_for_each_insn(file, func, insn) {
 				insn->sym = func;
-				if (func->type == STT_FUNC &&
+				if (is_func_sym(func) &&
 				    insn->type == INSN_ENDBR &&
 				    list_empty(&insn->call_node)) {
 					if (insn->offset == func->offset) {
@@ -561,7 +561,7 @@ static int add_pv_ops(struct objtool_file *file, const char *symname)
 		idx = (reloc_offset(reloc) - sym->offset) / sizeof(unsigned long);
 
 		func = reloc->sym;
-		if (func->type == STT_SECTION)
+		if (is_sec_sym(func))
 			func = find_symbol_by_offset(reloc->sym->sec,
 						     reloc_addend(reloc));
 		if (!func) {
@@ -823,7 +823,7 @@ static int create_ibt_endbr_seal_sections(struct objtool_file *file)
 		struct symbol *sym = insn->sym;
 		*site = 0;
 
-		if (opts.module && sym && sym->type == STT_FUNC &&
+		if (opts.module && sym && is_func_sym(sym) &&
 		    insn->offset == sym->offset &&
 		    (!strcmp(sym->name, "init_module") ||
 		     !strcmp(sym->name, "cleanup_module"))) {
@@ -858,7 +858,7 @@ static int create_cfi_sections(struct objtool_file *file)
 
 	idx = 0;
 	for_each_sym(file->elf, sym) {
-		if (sym->type != STT_FUNC)
+		if (!is_func_sym(sym))
 			continue;
 
 		if (strncmp(sym->name, "__cfi_", 6))
@@ -874,7 +874,7 @@ static int create_cfi_sections(struct objtool_file *file)
 
 	idx = 0;
 	for_each_sym(file->elf, sym) {
-		if (sym->type != STT_FUNC)
+		if (!is_func_sym(sym))
 			continue;
 
 		if (strncmp(sym->name, "__cfi_", 6))
@@ -1463,7 +1463,7 @@ static bool jump_is_sibling_call(struct objtool_file *file,
 		return false;
 
 	/* Disallow sibling calls into STT_NOTYPE */
-	if (ts->type == STT_NOTYPE)
+	if (is_notype_sym(ts))
 		return false;
 
 	/* Must not be self to be a sibling */
@@ -1497,7 +1497,7 @@ static int add_jump_destinations(struct objtool_file *file)
 		if (!reloc) {
 			dest_sec = insn->sec;
 			dest_off = arch_jump_destination(insn);
-		} else if (reloc->sym->type == STT_SECTION) {
+		} else if (is_sec_sym(reloc->sym)) {
 			dest_sec = reloc->sym->sec;
 			dest_off = arch_insn_adjusted_addend(insn, reloc);
 		} else if (reloc->sym->retpoline_thunk) {
@@ -1657,12 +1657,12 @@ static int add_call_destinations(struct objtool_file *file)
 				return -1;
 			}
 
-			if (func && insn_call_dest(insn)->type != STT_FUNC) {
+			if (func && !is_func_sym(insn_call_dest(insn))) {
 				ERROR_INSN(insn, "unsupported call to non-function");
 				return -1;
 			}
 
-		} else if (reloc->sym->type == STT_SECTION) {
+		} else if (is_sec_sym(reloc->sym)) {
 			dest_off = arch_insn_adjusted_addend(insn, reloc);
 			dest = find_call_destination(reloc->sym->sec, dest_off);
 			if (!dest) {
@@ -2146,7 +2146,7 @@ static int add_jump_table_alts(struct objtool_file *file)
 		return 0;
 
 	for_each_sym(file->elf, func) {
-		if (func->type != STT_FUNC)
+		if (!is_func_sym(func))
 			continue;
 
 		mark_func_jump_tables(file, func);
@@ -2185,14 +2185,14 @@ static int read_unwind_hints(struct objtool_file *file)
 		return -1;
 	}
 
-	if (sec->sh.sh_size % sizeof(struct unwind_hint)) {
+	if (sec_size(sec) % sizeof(struct unwind_hint)) {
 		ERROR("struct unwind_hint size mismatch");
 		return -1;
 	}
 
 	file->hints = true;
 
-	for (i = 0; i < sec->sh.sh_size / sizeof(struct unwind_hint); i++) {
+	for (i = 0; i < sec_size(sec) / sizeof(struct unwind_hint); i++) {
 		hint = (struct unwind_hint *)sec->data->d_buf + i;
 
 		reloc = find_reloc_by_dest(file->elf, sec, i * sizeof(*hint));
@@ -2201,7 +2201,7 @@ static int read_unwind_hints(struct objtool_file *file)
 			return -1;
 		}
 
-		if (reloc->sym->type == STT_SECTION) {
+		if (is_sec_sym(reloc->sym)) {
 			offset = reloc_addend(reloc);
 		} else if (reloc->sym->local_label) {
 			offset = reloc->sym->offset;
@@ -2237,7 +2237,7 @@ static int read_unwind_hints(struct objtool_file *file)
 		if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
 			struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
 
-			if (sym && sym->bind == STB_GLOBAL) {
+			if (sym && is_global_sym(sym)) {
 				if (opts.ibt && insn->type != INSN_ENDBR && !insn->noendbr) {
 					ERROR_INSN(insn, "UNWIND_HINT_IRET_REGS without ENDBR");
 					return -1;
@@ -2452,10 +2452,10 @@ static int classify_symbols(struct objtool_file *file)
 	struct symbol *func;
 
 	for_each_sym(file->elf, func) {
-		if (func->type == STT_NOTYPE && strstarts(func->name, ".L"))
+		if (is_notype_sym(func) && strstarts(func->name, ".L"))
 			func->local_label = true;
 
-		if (func->bind != STB_GLOBAL)
+		if (!is_global_sym(func))
 			continue;
 
 		if (!strncmp(func->name, STATIC_CALL_TRAMP_PREFIX_STR,
@@ -4179,11 +4179,11 @@ static int add_prefix_symbols(struct objtool_file *file)
 	struct symbol *func;
 
 	for_each_sec(file->elf, sec) {
-		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+		if (!is_text_sec(sec))
 			continue;
 
 		sec_for_each_sym(sec, func) {
-			if (func->type != STT_FUNC)
+			if (!is_func_sym(func))
 				continue;
 
 			add_prefix_symbol(file, func);
@@ -4227,7 +4227,7 @@ static int validate_section(struct objtool_file *file, struct section *sec)
 	int warnings = 0;
 
 	sec_for_each_sym(sec, func) {
-		if (func->type != STT_FUNC)
+		if (!is_func_sym(func))
 			continue;
 
 		init_insn_state(file, &state, sec);
@@ -4271,7 +4271,7 @@ static int validate_functions(struct objtool_file *file)
 	int warnings = 0;
 
 	for_each_sec(file->elf, sec) {
-		if (!(sec->sh.sh_flags & SHF_EXECINSTR))
+		if (!is_text_sec(sec))
 			continue;
 
 		warnings += validate_section(file, sec);
@@ -4452,7 +4452,7 @@ static int validate_ibt(struct objtool_file *file)
 	for_each_sec(file->elf, sec) {
 
 		/* Already done by validate_ibt_insn() */
-		if (sec->sh.sh_flags & SHF_EXECINSTR)
+		if (is_text_sec(sec))
 			continue;
 
 		if (!sec->rsec)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index c27edeed2dd0..d36c0d42fd7b 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -170,7 +170,7 @@ struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset)
 	struct symbol *iter;
 
 	__sym_for_each(iter, tree, offset, offset) {
-		if (iter->offset == offset && iter->type != STT_SECTION)
+		if (iter->offset == offset && !is_sec_sym(iter))
 			return iter;
 	}
 
@@ -183,7 +183,7 @@ struct symbol *find_func_by_offset(struct section *sec, unsigned long offset)
 	struct symbol *iter;
 
 	__sym_for_each(iter, tree, offset, offset) {
-		if (iter->offset == offset && iter->type == STT_FUNC)
+		if (iter->offset == offset && is_func_sym(iter))
 			return iter;
 	}
 
@@ -264,7 +264,7 @@ struct symbol *find_func_containing(struct section *sec, unsigned long offset)
 	struct symbol *iter;
 
 	__sym_for_each(iter, tree, offset, offset) {
-		if (iter->type == STT_FUNC)
+		if (is_func_sym(iter))
 			return iter;
 	}
 
@@ -373,14 +373,14 @@ static int read_sections(struct elf *elf)
 			return -1;
 		}
 
-		if (sec->sh.sh_size != 0 && !is_dwarf_section(sec)) {
+		if (sec_size(sec) != 0 && !is_dwarf_section(sec)) {
 			sec->data = elf_getdata(s, NULL);
 			if (!sec->data) {
 				ERROR_ELF("elf_getdata");
 				return -1;
 			}
 			if (sec->data->d_off != 0 ||
-			    sec->data->d_size != sec->sh.sh_size) {
+			    sec->data->d_size != sec_size(sec)) {
 				ERROR("unexpected data attributes for %s", sec->name);
 				return -1;
 			}
@@ -420,7 +420,7 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
 	sym->type = GELF_ST_TYPE(sym->sym.st_info);
 	sym->bind = GELF_ST_BIND(sym->sym.st_info);
 
-	if (sym->type == STT_FILE)
+	if (is_file_sym(sym))
 		elf->num_files++;
 
 	sym->offset = sym->sym.st_value;
@@ -527,7 +527,7 @@ static int read_symbols(struct elf *elf)
 		sec_for_each_sym(sec, sym) {
 			char *pname;
 			size_t pnamelen;
-			if (sym->type != STT_FUNC)
+			if (!is_func_sym(sym))
 				continue;
 
 			if (sym->pfunc == NULL)
@@ -929,7 +929,7 @@ struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
 	struct symbol *sym = insn_sec->sym;
 	int addend = insn_off;
 
-	if (!(insn_sec->sh.sh_flags & SHF_EXECINSTR)) {
+	if (!is_text_sec(insn_sec)) {
 		ERROR("bad call to %s() for data symbol %s", __func__, sym->name);
 		return NULL;
 	}
@@ -958,7 +958,7 @@ struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,
 				      struct symbol *sym,
 				      s64 addend)
 {
-	if (sym->sec && (sec->sh.sh_flags & SHF_EXECINSTR)) {
+	if (is_text_sec(sec)) {
 		ERROR("bad call to %s() for text symbol %s", __func__, sym->name);
 		return NULL;
 	}
@@ -1287,7 +1287,7 @@ int elf_write_insn(struct elf *elf, struct section *sec,
  */
 static int elf_truncate_section(struct elf *elf, struct section *sec)
 {
-	u64 size = sec->sh.sh_size;
+	u64 size = sec_size(sec);
 	bool truncated = false;
 	Elf_Data *data = NULL;
 	Elf_Scn *s;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 4d5f27b49724..f2dbcaa42a9c 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -8,6 +8,7 @@
 
 #include <stdio.h>
 #include <gelf.h>
+#include <linux/string.h>
 #include <linux/list.h>
 #include <linux/hashtable.h>
 #include <linux/rbtree.h>
@@ -178,11 +179,71 @@ static inline unsigned int elf_text_rela_type(struct elf *elf)
 	return elf_addr_size(elf) == 4 ? R_TEXT32 : R_TEXT64;
 }
 
+static inline bool sym_has_sec(struct symbol *sym)
+{
+	return sym->sec->idx;
+}
+
+static inline bool is_null_sym(struct symbol *sym)
+{
+	return !sym->idx;
+}
+
+static inline bool is_sec_sym(struct symbol *sym)
+{
+	return sym->type == STT_SECTION;
+}
+
+static inline bool is_object_sym(struct symbol *sym)
+{
+	return sym->type == STT_OBJECT;
+}
+
+static inline bool is_func_sym(struct symbol *sym)
+{
+	return sym->type == STT_FUNC;
+}
+
+static inline bool is_file_sym(struct symbol *sym)
+{
+	return sym->type == STT_FILE;
+}
+
+static inline bool is_notype_sym(struct symbol *sym)
+{
+	return sym->type == STT_NOTYPE;
+}
+
+static inline bool is_global_sym(struct symbol *sym)
+{
+	return sym->bind == STB_GLOBAL;
+}
+
+static inline bool is_weak_sym(struct symbol *sym)
+{
+	return sym->bind == STB_WEAK;
+}
+
+static inline bool is_local_sym(struct symbol *sym)
+{
+	return sym->bind == STB_LOCAL;
+}
+
 static inline bool is_reloc_sec(struct section *sec)
 {
 	return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
 }
 
+static inline bool is_string_sec(struct section *sec)
+{
+	return sec->sh.sh_flags & SHF_STRINGS;
+}
+
+static inline bool is_text_sec(struct section *sec)
+{
+	return sec->sh.sh_flags & SHF_EXECINSTR;
+}
+
 static inline bool sec_changed(struct section *sec)
 {
 	return sec->_changed;
@@ -223,6 +284,11 @@ static inline bool is_32bit_reloc(struct reloc *reloc)
 	return reloc->sec->sh.sh_entsize < 16;
 }
 
+static inline unsigned long sec_size(struct section *sec)
+{
+	return sec->sh.sh_size;
+}
+
 #define __get_reloc_field(reloc, field)					\
 ({									\
 	is_32bit_reloc(reloc) ?						\
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index c0beefb93b62..fc2cf8dba1c0 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -142,12 +142,12 @@ int special_get_alts(struct elf *elf, struct list_head *alts)
 		if (!sec)
 			continue;
 
-		if (sec->sh.sh_size % entry->size != 0) {
+		if (sec_size(sec) % entry->size != 0) {
 			ERROR("%s size not a multiple of %d", sec->name, entry->size);
 			return -1;
 		}
 
-		nr_entries = sec->sh.sh_size / entry->size;
+		nr_entries = sec_size(sec) / entry->size;
 
 		for (idx = 0; idx < nr_entries; idx++) {
 			alt = malloc(sizeof(*alt));
-- 
cgit v1.2.3


From 4ea029389bf0cc44da6d3a24a520200e060ce6bf Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:37 -0700
Subject: objtool: Mark .cold subfunctions

Introduce a flag to identify .cold subfunctions so they can be detected
easier and faster.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c               | 14 ++++++--------
 tools/objtool/elf.c                 | 19 ++++++++++---------
 tools/objtool/include/objtool/elf.h |  1 +
 3 files changed, 17 insertions(+), 17 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index f38f4a2e4e29..1d28ff73ebc9 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1575,7 +1575,9 @@ static int add_jump_destinations(struct objtool_file *file)
 		/*
 		 * Cross-function jump.
 		 */
-		if (func && insn_func(jump_dest) && func != insn_func(jump_dest)) {
+
+		if (func && insn_func(jump_dest) && !func->cold &&
+		    insn_func(jump_dest)->cold) {
 
 			/*
 			 * For GCC 8+, create parent/child links for any cold
@@ -1592,11 +1594,8 @@ static int add_jump_destinations(struct objtool_file *file)
 			 * case where the parent function's only reference to a
 			 * subfunction is through a jump table.
 			 */
-			if (!strstr(func->name, ".cold") &&
-			    strstr(insn_func(jump_dest)->name, ".cold")) {
-				func->cfunc = insn_func(jump_dest);
-				insn_func(jump_dest)->pfunc = func;
-			}
+			func->cfunc = insn_func(jump_dest);
+			insn_func(jump_dest)->pfunc = func;
 		}
 
 		if (jump_is_sibling_call(file, insn, jump_dest)) {
@@ -4066,9 +4065,8 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
 			 * If this hole jumps to a .cold function, mark it ignore too.
 			 */
 			if (insn->jump_dest && insn_func(insn->jump_dest) &&
-			    strstr(insn_func(insn->jump_dest)->name, ".cold")) {
+			    insn_func(insn->jump_dest)->cold)
 				insn_func(insn->jump_dest)->ignore = true;
-			}
 		}
 
 		return false;
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index d36c0d42fd7b..59568381486c 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -441,6 +441,10 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
 	list_add(&sym->list, entry);
 	elf_hash_add(symbol, &sym->hash, sym->idx);
 	elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
+
+	if (is_func_sym(sym) && strstr(sym->name, ".cold"))
+		sym->cold = 1;
+	sym->pfunc = sym->cfunc = sym;
 }
 
 static int read_symbols(struct elf *elf)
@@ -527,18 +531,15 @@ static int read_symbols(struct elf *elf)
 		sec_for_each_sym(sec, sym) {
 			char *pname;
 			size_t pnamelen;
-			if (!is_func_sym(sym))
-				continue;
 
-			if (sym->pfunc == NULL)
-				sym->pfunc = sym;
-
-			if (sym->cfunc == NULL)
-				sym->cfunc = sym;
+			if (!sym->cold)
+				continue;
 
 			coldstr = strstr(sym->name, ".cold");
-			if (!coldstr)
-				continue;
+			if (!coldstr) {
+				ERROR("%s(): cold subfunction without \".cold\"?", sym->name);
+				return -1;
+			}
 
 			pnamelen = coldstr - sym->name;
 			pname = strndup(sym->name, pnamelen);
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index f2dbcaa42a9c..dbadcc88a3b2 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -72,6 +72,7 @@ struct symbol {
 	u8 frame_pointer     : 1;
 	u8 ignore	     : 1;
 	u8 nocfi             : 1;
+	u8 cold		     : 1;
 	struct list_head pv_target;
 	struct reloc *relocs;
 	struct section *group_sec;
-- 
cgit v1.2.3


From c9e9b85d41f9079d6a10faabf70a0b18d5c0f177 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:38 -0700
Subject: objtool: Fix weak symbol hole detection for .cold functions

When ignore_unreachable_insn() looks for weak function holes which jump
to their .cold functions, it assumes the parent function comes before
the corresponding .cold function in the symbol table.  That's not
necessarily the case with -ffunction-sections.

Mark all the holes beforehand (including .cold functions) so the
ordering of the discovery doesn't matter.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c                 | 84 ++++++++++++++++++-----------------
 tools/objtool/include/objtool/check.h |  3 +-
 2 files changed, 45 insertions(+), 42 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 1d28ff73ebc9..86f6e4da536c 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2507,6 +2507,44 @@ static void mark_rodata(struct objtool_file *file)
 	file->rodata = found;
 }
 
+static void mark_holes(struct objtool_file *file)
+{
+	struct instruction *insn;
+	bool in_hole = false;
+
+	if (!opts.link)
+		return;
+
+	/*
+	 * Whole archive runs might encounter dead code from weak symbols.
+	 * This is where the linker will have dropped the weak symbol in
+	 * favour of a regular symbol, but leaves the code in place.
+	 */
+	for_each_insn(file, insn) {
+		if (insn->sym || !find_symbol_hole_containing(insn->sec, insn->offset)) {
+			in_hole = false;
+			continue;
+		}
+
+		/* Skip function padding and pfx code */
+		if (!in_hole && insn->type == INSN_NOP)
+			continue;
+
+		in_hole = true;
+		insn->hole = 1;
+
+		/*
+		 * If this hole jumps to a .cold function, mark it ignore.
+		 */
+		if (insn->jump_dest) {
+			struct symbol *dest_func = insn_func(insn->jump_dest);
+
+			if (dest_func && dest_func->cold)
+				dest_func->ignore = true;
+		}
+	}
+}
+
 static int decode_sections(struct objtool_file *file)
 {
 	mark_rodata(file);
@@ -2560,6 +2598,9 @@ static int decode_sections(struct objtool_file *file)
 	if (read_unwind_hints(file))
 		return -1;
 
+	/* Must be after add_jump_destinations() */
+	mark_holes(file);
+
 	/*
 	 * Must be after add_call_destinations() such that it can override
 	 * dead_end_function() marks.
@@ -4021,7 +4062,8 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
 	struct instruction *prev_insn;
 	int i;
 
-	if (insn->type == INSN_NOP || insn->type == INSN_TRAP || (func && func->ignore))
+	if (insn->type == INSN_NOP || insn->type == INSN_TRAP ||
+	    insn->hole || (func && func->ignore))
 		return true;
 
 	/*
@@ -4032,46 +4074,6 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
 	    !strcmp(insn->sec->name, ".altinstr_aux"))
 		return true;
 
-	/*
-	 * Whole archive runs might encounter dead code from weak symbols.
-	 * This is where the linker will have dropped the weak symbol in
-	 * favour of a regular symbol, but leaves the code in place.
-	 *
-	 * In this case we'll find a piece of code (whole function) that is not
-	 * covered by a !section symbol. Ignore them.
-	 */
-	if (opts.link && !func) {
-		int size = find_symbol_hole_containing(insn->sec, insn->offset);
-		unsigned long end = insn->offset + size;
-
-		if (!size) /* not a hole */
-			return false;
-
-		if (size < 0) /* hole until the end */
-			return true;
-
-		sec_for_each_insn_continue(file, insn) {
-			/*
-			 * If we reach a visited instruction at or before the
-			 * end of the hole, ignore the unreachable.
-			 */
-			if (insn->visited)
-				return true;
-
-			if (insn->offset >= end)
-				break;
-
-			/*
-			 * If this hole jumps to a .cold function, mark it ignore too.
-			 */
-			if (insn->jump_dest && insn_func(insn->jump_dest) &&
-			    insn_func(insn->jump_dest)->cold)
-				insn_func(insn->jump_dest)->ignore = true;
-		}
-
-		return false;
-	}
-
 	if (!func)
 		return false;
 
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 00fb745e7233..0f4e7ac929ef 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -64,7 +64,8 @@ struct instruction {
 	    noendbr		: 1,
 	    unret		: 1,
 	    visited		: 4,
-	    no_reloc		: 1;
+	    no_reloc		: 1,
+	    hole		: 1;
 		/* 10 bit hole */
 
 	struct alt_group *alt_group;
-- 
cgit v1.2.3


From a1526bcfcb6cb7cb601b9ff8e24d08881ef9afb8 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:39 -0700
Subject: objtool: Mark prefix functions

In preparation for the objtool klp diff subcommand, introduce a flag to
identify __pfx_*() and __cfi_*() functions in advance so they don't need
to be manually identified every time a check is needed.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c               | 5 +----
 tools/objtool/elf.c                 | 7 +++++++
 tools/objtool/include/objtool/elf.h | 6 ++++++
 3 files changed, 14 insertions(+), 4 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 86f6e4da536c..46b425fade4f 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3568,10 +3568,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 
 		if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
 			/* Ignore KCFI type preambles, which always fall through */
-			if (!strncmp(func->name, "__cfi_", 6) ||
-			    !strncmp(func->name, "__pfx_", 6) ||
-			    !strncmp(func->name, "__pi___cfi_", 11) ||
-			    !strncmp(func->name, "__pi___pfx_", 11))
+			if (is_prefix_func(func))
 				return 0;
 
 			if (file->ignore_unreachables)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 59568381486c..775d017b1b79 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -442,6 +442,13 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
 	elf_hash_add(symbol, &sym->hash, sym->idx);
 	elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
 
+	if (is_func_sym(sym) &&
+	    (strstarts(sym->name, "__pfx_") ||
+	     strstarts(sym->name, "__cfi_") ||
+	     strstarts(sym->name, "__pi___pfx_") ||
+	     strstarts(sym->name, "__pi___cfi_")))
+		sym->prefix = 1;
+
 	if (is_func_sym(sym) && strstr(sym->name, ".cold"))
 		sym->cold = 1;
 	sym->pfunc = sym->cfunc = sym;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index dbadcc88a3b2..79edf82e76dd 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -73,6 +73,7 @@ struct symbol {
 	u8 ignore	     : 1;
 	u8 nocfi             : 1;
 	u8 cold		     : 1;
+	u8 prefix	     : 1;
 	struct list_head pv_target;
 	struct reloc *relocs;
 	struct section *group_sec;
@@ -230,6 +231,11 @@ static inline bool is_local_sym(struct symbol *sym)
 	return sym->bind == STB_LOCAL;
 }
 
+static inline bool is_prefix_func(struct symbol *sym)
+{
+	return sym->prefix;
+}
+
 static inline bool is_reloc_sec(struct section *sec)
 {
 	return sec->sh.sh_type == SHT_RELA || sec->sh.sh_type == SHT_REL;
-- 
cgit v1.2.3


From a040ab73dfd1bc8198848a438f77497d8d03fba9 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:40 -0700
Subject: objtool: Simplify reloc offset calculation in unwind_read_hints()

Simplify the relocation offset calculation in unwind_read_hints(),
similar to other conversions which have already been done.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 46b425fade4f..473e73722d5c 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2200,14 +2200,7 @@ static int read_unwind_hints(struct objtool_file *file)
 			return -1;
 		}
 
-		if (is_sec_sym(reloc->sym)) {
-			offset = reloc_addend(reloc);
-		} else if (reloc->sym->local_label) {
-			offset = reloc->sym->offset;
-		} else {
-			ERROR("unexpected relocation symbol type in %s", sec->rsec->name);
-			return -1;
-		}
+		offset = reloc->sym->offset + reloc_addend(reloc);
 
 		insn = find_insn(file, reloc->sym->sec, offset);
 		if (!insn) {
-- 
cgit v1.2.3


From 48f1bbaf2655c8178249cf10f1a50fac0a72e467 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:41 -0700
Subject: objtool: Avoid emptying lists for duplicate sections

When a to-be-created section already exists, there's no point in
emptying the various lists if their respective sections already exist.
In fact it's better to leave them intact as they might get used later.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c | 4 ----
 1 file changed, 4 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 473e73722d5c..e567a625b9e0 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -635,7 +635,6 @@ static int create_static_call_sections(struct objtool_file *file)
 
 	sec = find_section_by_name(file->elf, ".static_call_sites");
 	if (sec) {
-		INIT_LIST_HEAD(&file->static_call_list);
 		WARN("file already has .static_call_sites section, skipping");
 		return 0;
 	}
@@ -851,7 +850,6 @@ static int create_cfi_sections(struct objtool_file *file)
 
 	sec = find_section_by_name(file->elf, ".cfi_sites");
 	if (sec) {
-		INIT_LIST_HEAD(&file->call_list);
 		WARN("file already has .cfi_sites section, skipping");
 		return 0;
 	}
@@ -900,7 +898,6 @@ static int create_mcount_loc_sections(struct objtool_file *file)
 
 	sec = find_section_by_name(file->elf, "__mcount_loc");
 	if (sec) {
-		INIT_LIST_HEAD(&file->mcount_loc_list);
 		WARN("file already has __mcount_loc section, skipping");
 		return 0;
 	}
@@ -945,7 +942,6 @@ static int create_direct_call_sections(struct objtool_file *file)
 
 	sec = find_section_by_name(file->elf, ".call_sites");
 	if (sec) {
-		INIT_LIST_HEAD(&file->call_list);
 		WARN("file already has .call_sites section, skipping");
 		return 0;
 	}
-- 
cgit v1.2.3


From 56754f0f46f6a36ba66e8c1b2878f7a4f1edfe3b Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:42 -0700
Subject: objtool: Rename --Werror to --werror

The objtool --Werror option name is stylistically inconsistent: halfway
between GCC's single-dash capitalized -Werror and objtool's double-dash
--lowercase convention, making it unnecessarily hard to remember.

Make the 'W' lower case (--werror) for consistency with objtool's other
options.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/builtin-check.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index fcd4a6517896..2aa28af8fb09 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -101,7 +101,7 @@ static const struct option check_options[] = {
 	OPT_BOOLEAN(0,   "sec-address", &opts.sec_address, "print section addresses in warnings"),
 	OPT_BOOLEAN(0,   "stats", &opts.stats, "print statistics"),
 	OPT_BOOLEAN('v', "verbose", &opts.verbose, "verbose warnings"),
-	OPT_BOOLEAN(0,   "Werror", &opts.werror, "return error on warnings"),
+	OPT_BOOLEAN(0,   "werror", &opts.werror, "return error on warnings"),
 
 	OPT_END(),
 };
-- 
cgit v1.2.3


From 2b91479776b66cd815e339d420abbf4ae047bfb2 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:43 -0700
Subject: objtool: Resurrect --backup option

The --backup option was removed with the following commit:

  aa8b3e64fd39 ("objtool: Create backup on error and print args")

... which tied the backup functionality to --verbose, and only for
warnings/errors.

It's a bit inelegant and out of scope to tie that to --verbose.

Bring back the old --backup option, but with the new behavior: only on
warnings/errors, and print the args to make it easier to recreate.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/builtin-check.c           | 25 +++++++++++--------------
 tools/objtool/check.c                   |  4 +++-
 tools/objtool/include/objtool/builtin.h |  3 ++-
 3 files changed, 16 insertions(+), 16 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 2aa28af8fb09..2abac92cdaef 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -92,6 +92,7 @@ static const struct option check_options[] = {
 
 	OPT_GROUP("Options:"),
 	OPT_BOOLEAN(0,   "backtrace", &opts.backtrace, "unwind on error"),
+	OPT_BOOLEAN(0,   "backup", &opts.backup, "create backup (.orig) file on warning/error"),
 	OPT_BOOLEAN(0,   "dry-run", &opts.dryrun, "don't write modifications"),
 	OPT_BOOLEAN(0,   "link", &opts.link, "object is a linked object"),
 	OPT_BOOLEAN(0,   "module", &opts.module, "object is part of a kernel module"),
@@ -246,12 +247,9 @@ static void save_argv(int argc, const char **argv)
 	}
 }
 
-void print_args(void)
+int make_backup(void)
 {
-	char *backup = NULL;
-
-	if (opts.output || opts.dryrun)
-		goto print;
+	char *backup;
 
 	/*
 	 * Make a backup before kbuild deletes the file so the error
@@ -260,33 +258,32 @@ void print_args(void)
 	backup = malloc(strlen(objname) + strlen(ORIG_SUFFIX) + 1);
 	if (!backup) {
 		ERROR_GLIBC("malloc");
-		goto print;
+		return 1;
 	}
 
 	strcpy(backup, objname);
 	strcat(backup, ORIG_SUFFIX);
-	if (copy_file(objname, backup)) {
-		backup = NULL;
-		goto print;
-	}
+	if (copy_file(objname, backup))
+		return 1;
 
-print:
 	/*
-	 * Print the cmdline args to make it easier to recreate.  If '--output'
-	 * wasn't used, add it to the printed args with the backup as input.
+	 * Print the cmdline args to make it easier to recreate.
 	 */
+
 	fprintf(stderr, "%s", orig_argv[0]);
 
 	for (int i = 1; i < orig_argc; i++) {
 		char *arg = orig_argv[i];
 
-		if (backup && !strcmp(arg, objname))
+		/* Modify the printed args to use the backup */
+		if (!opts.output && !strcmp(arg, objname))
 			fprintf(stderr, " %s -o %s", backup, objname);
 		else
 			fprintf(stderr, " %s", arg);
 	}
 
 	fprintf(stderr, "\n");
+	return 0;
 }
 
 int objtool_run(int argc, const char **argv)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index e567a625b9e0..b63f7c4182ef 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4824,9 +4824,11 @@ out:
 	if (opts.verbose) {
 		if (opts.werror && warnings)
 			WARN("%d warning(s) upgraded to errors", warnings);
-		print_args();
 		disas_warned_funcs(file);
 	}
 
+	if (opts.backup && make_backup())
+		return 1;
+
 	return ret;
 }
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index ab22673862e1..7d559a2c13b7 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -30,6 +30,7 @@ struct opts {
 
 	/* options: */
 	bool backtrace;
+	bool backup;
 	bool dryrun;
 	bool link;
 	bool mnop;
@@ -48,6 +49,6 @@ int cmd_parse_options(int argc, const char **argv, const char * const usage[]);
 
 int objtool_run(int argc, const char **argv);
 
-void print_args(void);
+int make_backup(void);
 
 #endif /* _BUILTIN_H */
-- 
cgit v1.2.3


From 935c0b6a059106c09bf5cdb70f42c1a8650843af Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:44 -0700
Subject: objtool: Reindent check_options[]

Bring the cmdline check_options[] array back into vertical alignment for
better readability.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/builtin-check.c | 54 +++++++++++++++++++++----------------------
 1 file changed, 27 insertions(+), 27 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 2abac92cdaef..fc91bc5cdb6b 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -73,36 +73,36 @@ static int parse_hacks(const struct option *opt, const char *str, int unset)
 
 static const struct option check_options[] = {
 	OPT_GROUP("Actions:"),
+	OPT_BOOLEAN(0,		 "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
 	OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
-	OPT_BOOLEAN('i', "ibt", &opts.ibt, "validate and annotate IBT"),
-	OPT_BOOLEAN('m', "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
-	OPT_BOOLEAN('n', "noinstr", &opts.noinstr, "validate noinstr rules"),
-	OPT_BOOLEAN(0,   "orc", &opts.orc, "generate ORC metadata"),
-	OPT_BOOLEAN('r', "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
-	OPT_BOOLEAN(0,   "rethunk", &opts.rethunk, "validate and annotate rethunk usage"),
-	OPT_BOOLEAN(0,   "unret", &opts.unret, "validate entry unret placement"),
-	OPT_INTEGER(0,   "prefix", &opts.prefix, "generate prefix symbols"),
-	OPT_BOOLEAN('l', "sls", &opts.sls, "validate straight-line-speculation mitigations"),
-	OPT_BOOLEAN('s', "stackval", &opts.stackval, "validate frame pointer rules"),
-	OPT_BOOLEAN('t', "static-call", &opts.static_call, "annotate static calls"),
-	OPT_BOOLEAN('u', "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
-	OPT_BOOLEAN(0  , "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
-	OPT_BOOLEAN(0  , "noabs", &opts.noabs, "reject absolute references in allocatable sections"),
-	OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
+	OPT_BOOLEAN('i',	 "ibt", &opts.ibt, "validate and annotate IBT"),
+	OPT_BOOLEAN('m',	 "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
+	OPT_BOOLEAN(0,		 "noabs", &opts.noabs, "reject absolute references in allocatable sections"),
+	OPT_BOOLEAN('n',	 "noinstr", &opts.noinstr, "validate noinstr rules"),
+	OPT_BOOLEAN(0,		 "orc", &opts.orc, "generate ORC metadata"),
+	OPT_BOOLEAN('r',	 "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
+	OPT_BOOLEAN(0,		 "rethunk", &opts.rethunk, "validate and annotate rethunk usage"),
+	OPT_BOOLEAN(0,		 "unret", &opts.unret, "validate entry unret placement"),
+	OPT_INTEGER(0,		 "prefix", &opts.prefix, "generate prefix symbols"),
+	OPT_BOOLEAN('l',	 "sls", &opts.sls, "validate straight-line-speculation mitigations"),
+	OPT_BOOLEAN('s',	 "stackval", &opts.stackval, "validate frame pointer rules"),
+	OPT_BOOLEAN('t',	 "static-call", &opts.static_call, "annotate static calls"),
+	OPT_BOOLEAN('u',	 "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
+	OPT_CALLBACK_OPTARG(0,	 "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
 
 	OPT_GROUP("Options:"),
-	OPT_BOOLEAN(0,   "backtrace", &opts.backtrace, "unwind on error"),
-	OPT_BOOLEAN(0,   "backup", &opts.backup, "create backup (.orig) file on warning/error"),
-	OPT_BOOLEAN(0,   "dry-run", &opts.dryrun, "don't write modifications"),
-	OPT_BOOLEAN(0,   "link", &opts.link, "object is a linked object"),
-	OPT_BOOLEAN(0,   "module", &opts.module, "object is part of a kernel module"),
-	OPT_BOOLEAN(0,   "mnop", &opts.mnop, "nop out mcount call sites"),
-	OPT_BOOLEAN(0,   "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
-	OPT_STRING('o',  "output", &opts.output, "file", "output file name"),
-	OPT_BOOLEAN(0,   "sec-address", &opts.sec_address, "print section addresses in warnings"),
-	OPT_BOOLEAN(0,   "stats", &opts.stats, "print statistics"),
-	OPT_BOOLEAN('v', "verbose", &opts.verbose, "verbose warnings"),
-	OPT_BOOLEAN(0,   "werror", &opts.werror, "return error on warnings"),
+	OPT_BOOLEAN(0,		 "backtrace", &opts.backtrace, "unwind on error"),
+	OPT_BOOLEAN(0,		 "backup", &opts.backup, "create backup (.orig) file on warning/error"),
+	OPT_BOOLEAN(0,		 "dry-run", &opts.dryrun, "don't write modifications"),
+	OPT_BOOLEAN(0,		 "link", &opts.link, "object is a linked object"),
+	OPT_BOOLEAN(0,		 "module", &opts.module, "object is part of a kernel module"),
+	OPT_BOOLEAN(0,		 "mnop", &opts.mnop, "nop out mcount call sites"),
+	OPT_BOOLEAN(0,		 "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
+	OPT_STRING('o',		 "output", &opts.output, "file", "output file name"),
+	OPT_BOOLEAN(0,		 "sec-address", &opts.sec_address, "print section addresses in warnings"),
+	OPT_BOOLEAN(0,		 "stats", &opts.stats, "print statistics"),
+	OPT_BOOLEAN('v',	 "verbose", &opts.verbose, "verbose warnings"),
+	OPT_BOOLEAN(0,		 "werror", &opts.werror, "return error on warnings"),
 
 	OPT_END(),
 };
-- 
cgit v1.2.3


From a05de0a772ce423895a3b07504a9ed93ae75e912 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:45 -0700
Subject: objtool: Refactor add_jump_destinations()

The add_jump_destinations() logic is a bit weird and convoluted after
being incrementally tweaked over the years.  Refactor it to hopefully be
more logical and straightforward.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c               | 212 +++++++++++++++++-------------------
 tools/objtool/include/objtool/elf.h |   4 +-
 2 files changed, 101 insertions(+), 115 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b63f7c4182ef..65a359cbf4ea 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1423,9 +1423,14 @@ static void add_return_call(struct objtool_file *file, struct instruction *insn,
 }
 
 static bool is_first_func_insn(struct objtool_file *file,
-			       struct instruction *insn, struct symbol *sym)
+			       struct instruction *insn)
 {
-	if (insn->offset == sym->offset)
+	struct symbol *func = insn_func(insn);
+
+	if (!func)
+		return false;
+
+	if (insn->offset == func->offset)
 		return true;
 
 	/* Allow direct CALL/JMP past ENDBR */
@@ -1433,51 +1438,30 @@ static bool is_first_func_insn(struct objtool_file *file,
 		struct instruction *prev = prev_insn_same_sym(file, insn);
 
 		if (prev && prev->type == INSN_ENDBR &&
-		    insn->offset == sym->offset + prev->len)
+		    insn->offset == func->offset + prev->len)
 			return true;
 	}
 
 	return false;
 }
 
-/*
- * A sibling call is a tail-call to another symbol -- to differentiate from a
- * recursive tail-call which is to the same symbol.
- */
-static bool jump_is_sibling_call(struct objtool_file *file,
-				 struct instruction *from, struct instruction *to)
-{
-	struct symbol *fs = from->sym;
-	struct symbol *ts = to->sym;
-
-	/* Not a sibling call if from/to a symbol hole */
-	if (!fs || !ts)
-		return false;
-
-	/* Not a sibling call if not targeting the start of a symbol. */
-	if (!is_first_func_insn(file, to, ts))
-		return false;
-
-	/* Disallow sibling calls into STT_NOTYPE */
-	if (is_notype_sym(ts))
-		return false;
-
-	/* Must not be self to be a sibling */
-	return fs->pfunc != ts->pfunc;
-}
-
 /*
  * Find the destination instructions for all jumps.
  */
 static int add_jump_destinations(struct objtool_file *file)
 {
-	struct instruction *insn, *jump_dest;
+	struct instruction *insn;
 	struct reloc *reloc;
-	struct section *dest_sec;
-	unsigned long dest_off;
 
 	for_each_insn(file, insn) {
 		struct symbol *func = insn_func(insn);
+		struct instruction *dest_insn;
+		struct section *dest_sec;
+		struct symbol *dest_sym;
+		unsigned long dest_off;
+
+		if (!is_static_jump(insn))
+			continue;
 
 		if (insn->jump_dest) {
 			/*
@@ -1486,51 +1470,53 @@ static int add_jump_destinations(struct objtool_file *file)
 			 */
 			continue;
 		}
-		if (!is_static_jump(insn))
-			continue;
 
 		reloc = insn_reloc(file, insn);
 		if (!reloc) {
 			dest_sec = insn->sec;
 			dest_off = arch_jump_destination(insn);
-		} else if (is_sec_sym(reloc->sym)) {
-			dest_sec = reloc->sym->sec;
-			dest_off = arch_insn_adjusted_addend(insn, reloc);
-		} else if (reloc->sym->retpoline_thunk) {
-			if (add_retpoline_call(file, insn))
-				return -1;
-			continue;
-		} else if (reloc->sym->return_thunk) {
-			add_return_call(file, insn, true);
-			continue;
-		} else if (func) {
-			/*
-			 * External sibling call or internal sibling call with
-			 * STT_FUNC reloc.
-			 */
-			if (add_call_dest(file, insn, reloc->sym, true))
-				return -1;
-			continue;
-		} else if (reloc->sym->sec->idx) {
-			dest_sec = reloc->sym->sec;
-			dest_off = reloc->sym->sym.st_value +
-				   arch_insn_adjusted_addend(insn, reloc);
+			dest_sym = dest_sec->sym;
 		} else {
-			/* non-func asm code jumping to another file */
-			continue;
+			dest_sym = reloc->sym;
+			if (is_undef_sym(dest_sym)) {
+				if (dest_sym->retpoline_thunk) {
+					if (add_retpoline_call(file, insn))
+						return -1;
+					continue;
+				}
+
+				if (dest_sym->return_thunk) {
+					add_return_call(file, insn, true);
+					continue;
+				}
+
+				/* External symbol */
+				if (func) {
+					/* External sibling call */
+					if (add_call_dest(file, insn, dest_sym, true))
+						return -1;
+					continue;
+				}
+
+				/* Non-func asm code jumping to external symbol */
+				continue;
+			}
+
+			dest_sec = dest_sym->sec;
+			dest_off = dest_sym->offset + arch_insn_adjusted_addend(insn, reloc);
 		}
 
-		jump_dest = find_insn(file, dest_sec, dest_off);
-		if (!jump_dest) {
+		dest_insn = find_insn(file, dest_sec, dest_off);
+		if (!dest_insn) {
 			struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
 
 			/*
-			 * This is a special case for retbleed_untrain_ret().
-			 * It jumps to __x86_return_thunk(), but objtool
-			 * can't find the thunk's starting RET
-			 * instruction, because the RET is also in the
-			 * middle of another instruction.  Objtool only
-			 * knows about the outer instruction.
+			 * retbleed_untrain_ret() jumps to
+			 * __x86_return_thunk(), but objtool can't find
+			 * the thunk's starting RET instruction,
+			 * because the RET is also in the middle of
+			 * another instruction.  Objtool only knows
+			 * about the outer instruction.
 			 */
 			if (sym && sym->embedded_insn) {
 				add_return_call(file, insn, false);
@@ -1538,73 +1524,73 @@ static int add_jump_destinations(struct objtool_file *file)
 			}
 
 			/*
-			 * GCOV/KCOV dead code can jump to the end of the
-			 * function/section.
+			 * GCOV/KCOV dead code can jump to the end of
+			 * the function/section.
 			 */
 			if (file->ignore_unreachables && func &&
 			    dest_sec == insn->sec &&
 			    dest_off == func->offset + func->len)
 				continue;
 
-			ERROR_INSN(insn, "can't find jump dest instruction at %s+0x%lx",
-				   dest_sec->name, dest_off);
+			ERROR_INSN(insn, "can't find jump dest instruction at %s",
+				   offstr(dest_sec, dest_off));
 			return -1;
 		}
 
-		/*
-		 * An intra-TU jump in retpoline.o might not have a relocation
-		 * for its jump dest, in which case the above
-		 * add_{retpoline,return}_call() didn't happen.
-		 */
-		if (jump_dest->sym && jump_dest->offset == jump_dest->sym->offset) {
-			if (jump_dest->sym->retpoline_thunk) {
-				if (add_retpoline_call(file, insn))
-					return -1;
-				continue;
-			}
-			if (jump_dest->sym->return_thunk) {
-				add_return_call(file, insn, true);
-				continue;
-			}
+		if (!dest_sym || is_sec_sym(dest_sym)) {
+			dest_sym = dest_insn->sym;
+			if (!dest_sym)
+				goto set_jump_dest;
+		}
+
+		if (dest_sym->retpoline_thunk && dest_insn->offset == dest_sym->offset) {
+			if (add_retpoline_call(file, insn))
+				return -1;
+			continue;
+		}
+
+		if (dest_sym->return_thunk && dest_insn->offset == dest_sym->offset) {
+			add_return_call(file, insn, true);
+			continue;
 		}
 
+		if (!insn->sym || insn->sym == dest_insn->sym)
+			goto set_jump_dest;
+
 		/*
-		 * Cross-function jump.
+		 * Internal cross-function jump.
 		 */
 
-		if (func && insn_func(jump_dest) && !func->cold &&
-		    insn_func(jump_dest)->cold) {
-
-			/*
-			 * For GCC 8+, create parent/child links for any cold
-			 * subfunctions.  This is _mostly_ redundant with a
-			 * similar initialization in read_symbols().
-			 *
-			 * If a function has aliases, we want the *first* such
-			 * function in the symbol table to be the subfunction's
-			 * parent.  In that case we overwrite the
-			 * initialization done in read_symbols().
-			 *
-			 * However this code can't completely replace the
-			 * read_symbols() code because this doesn't detect the
-			 * case where the parent function's only reference to a
-			 * subfunction is through a jump table.
-			 */
-			func->cfunc = insn_func(jump_dest);
-			insn_func(jump_dest)->pfunc = func;
+		/*
+		 * For GCC 8+, create parent/child links for any cold
+		 * subfunctions.  This is _mostly_ redundant with a
+		 * similar initialization in read_symbols().
+		 *
+		 * If a function has aliases, we want the *first* such
+		 * function in the symbol table to be the subfunction's
+		 * parent.  In that case we overwrite the
+		 * initialization done in read_symbols().
+		 *
+		 * However this code can't completely replace the
+		 * read_symbols() code because this doesn't detect the
+		 * case where the parent function's only reference to a
+		 * subfunction is through a jump table.
+		 */
+		if (func && dest_sym->cold) {
+			func->cfunc = dest_sym;
+			dest_sym->pfunc = func;
+			goto set_jump_dest;
 		}
 
-		if (jump_is_sibling_call(file, insn, jump_dest)) {
-			/*
-			 * Internal sibling call without reloc or with
-			 * STT_SECTION reloc.
-			 */
-			if (add_call_dest(file, insn, insn_func(jump_dest), true))
+		if (is_first_func_insn(file, dest_insn)) {
+			/* Internal sibling call */
+			if (add_call_dest(file, insn, dest_sym, true))
 				return -1;
 			continue;
 		}
 
-		insn->jump_dest = jump_dest;
+set_jump_dest:
+		insn->jump_dest = dest_insn;
 	}
 
 	return 0;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 79edf82e76dd..07fc41f574b9 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -181,9 +181,9 @@ static inline unsigned int elf_text_rela_type(struct elf *elf)
 	return elf_addr_size(elf) == 4 ? R_TEXT32 : R_TEXT64;
 }
 
-static inline bool sym_has_sec(struct symbol *sym)
+static inline bool is_undef_sym(struct symbol *sym)
 {
-	return sym->sec->idx;
+	return !sym->sec->idx;
 }
 
 static inline bool is_null_sym(struct symbol *sym)
-- 
cgit v1.2.3


From 02cf323a7ee07621f47369c547ae7c7505a7312a Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:46 -0700
Subject: objtool: Simplify special symbol handling in elf_update_symbol()

!sym->sec isn't actually a thing: even STT_UNDEF and other special
symbol types belong to NULL section 0.

Simplify the initialization of 'shndx' accordingly.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 775d017b1b79..c35726a47c07 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -637,7 +637,7 @@ static int elf_update_sym_relocs(struct elf *elf, struct symbol *sym)
 static int elf_update_symbol(struct elf *elf, struct section *symtab,
 			     struct section *symtab_shndx, struct symbol *sym)
 {
-	Elf32_Word shndx = sym->sec ? sym->sec->idx : SHN_UNDEF;
+	Elf32_Word shndx;
 	Elf_Data *symtab_data = NULL, *shndx_data = NULL;
 	Elf64_Xword entsize = symtab->sh.sh_entsize;
 	int max_idx, idx = sym->idx;
@@ -645,8 +645,7 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
 	bool is_special_shndx = sym->sym.st_shndx >= SHN_LORESERVE &&
 				sym->sym.st_shndx != SHN_XINDEX;
 
-	if (is_special_shndx)
-		shndx = sym->sym.st_shndx;
+	shndx = is_special_shndx ? sym->sym.st_shndx : sym->sec->idx;
 
 	s = elf_getscn(elf->elf, symtab->idx);
 	if (!s) {
-- 
cgit v1.2.3


From dd2c29aafde7653839791d3073515b62e5df1f4d Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:47 -0700
Subject: objtool: Generalize elf_create_symbol()

In preparation for the objtool klp diff subcommand, broaden the
elf_create_symbol() interface to give callers more control and reduce
duplication of some subtle setup logic.

While at it, make elf_create_symbol() and elf_create_section_symbol()
global so sections can be created by the upcoming klp diff code.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c                 | 111 +++++++++++++++++++-----------------
 tools/objtool/include/objtool/elf.h |  11 +++-
 2 files changed, 69 insertions(+), 53 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index c35726a47c07..d7703c848ce0 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -763,24 +763,60 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
 	return 0;
 }
 
-static struct symbol *
-__elf_create_symbol(struct elf *elf, struct symbol *sym)
+static int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
+
+struct symbol *elf_create_symbol(struct elf *elf, const char *name,
+				 struct section *sec, unsigned int bind,
+				 unsigned int type, unsigned long offset,
+				 size_t size)
 {
 	struct section *symtab, *symtab_shndx;
 	Elf32_Word first_non_local, new_idx;
-	struct symbol *old;
+	struct symbol *old, *sym;
 
-	symtab = find_section_by_name(elf, ".symtab");
-	if (symtab) {
-		symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
+	sym = calloc(1, sizeof(*sym));
+	if (!sym) {
+		ERROR_GLIBC("calloc");
+		return NULL;
+	}
+
+	sym->name = strdup(name);
+	if (!sym->name) {
+		ERROR_GLIBC("strdup");
+		return NULL;
+	}
+
+	if (type != STT_SECTION) {
+		sym->sym.st_name = elf_add_string(elf, NULL, sym->name);
+		if (sym->sym.st_name == -1)
+			return NULL;
+	}
+
+	if (sec) {
+		sym->sec = sec;
 	} else {
+		sym->sec = find_section_by_index(elf, 0);
+		if (!sym->sec) {
+			ERROR("no NULL section");
+			return NULL;
+		}
+	}
+
+	sym->sym.st_info  = GELF_ST_INFO(bind, type);
+	sym->sym.st_value = offset;
+	sym->sym.st_size  = size;
+
+	symtab = find_section_by_name(elf, ".symtab");
+	if (!symtab) {
 		ERROR("no .symtab");
 		return NULL;
 	}
 
+	symtab_shndx = find_section_by_name(elf, ".symtab_shndx");
+
 	new_idx = sec_num_entries(symtab);
 
-	if (GELF_ST_BIND(sym->sym.st_info) != STB_LOCAL)
+	if (bind != STB_LOCAL)
 		goto non_local;
 
 	/*
@@ -818,10 +854,8 @@ __elf_create_symbol(struct elf *elf, struct symbol *sym)
 
 non_local:
 	sym->idx = new_idx;
-	if (elf_update_symbol(elf, symtab, symtab_shndx, sym)) {
-		ERROR("elf_update_symbol");
+	if (sym->idx && elf_update_symbol(elf, symtab, symtab_shndx, sym))
 		return NULL;
-	}
 
 	symtab->sh.sh_size += symtab->sh.sh_entsize;
 	mark_sec_changed(elf, symtab, true);
@@ -831,64 +865,39 @@ non_local:
 		mark_sec_changed(elf, symtab_shndx, true);
 	}
 
+	elf_add_symbol(elf, sym);
+
 	return sym;
 }
 
-static struct symbol *
-elf_create_section_symbol(struct elf *elf, struct section *sec)
+struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec)
 {
 	struct symbol *sym = calloc(1, sizeof(*sym));
 
-	if (!sym) {
-		ERROR_GLIBC("malloc");
+	sym = elf_create_symbol(elf, sec->name, sec, STB_LOCAL, STT_SECTION, 0, 0);
+	if (!sym)
 		return NULL;
-	}
-
-	sym->name = sec->name;
-	sym->sec = sec;
 
-	// st_name 0
-	sym->sym.st_info = GELF_ST_INFO(STB_LOCAL, STT_SECTION);
-	// st_other 0
-	// st_value 0
-	// st_size 0
-
-	sym = __elf_create_symbol(elf, sym);
-	if (sym)
-		elf_add_symbol(elf, sym);
+	sec->sym = sym;
 
 	return sym;
 }
 
-static int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
-
 struct symbol *
-elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size)
+elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, size_t size)
 {
-	struct symbol *sym = calloc(1, sizeof(*sym));
 	size_t namelen = strlen(orig->name) + sizeof("__pfx_");
-	char *name = malloc(namelen);
-
-	if (!sym || !name) {
-		ERROR_GLIBC("malloc");
-		return NULL;
-	}
+	char name[SYM_NAME_LEN];
+	unsigned long offset;
 
 	snprintf(name, namelen, "__pfx_%s", orig->name);
 
-	sym->name = name;
-	sym->sec = orig->sec;
+	offset = orig->sym.st_value - size;
 
-	sym->sym.st_name = elf_add_string(elf, NULL, name);
-	sym->sym.st_info = orig->sym.st_info;
-	sym->sym.st_value = orig->sym.st_value - size;
-	sym->sym.st_size = size;
-
-	sym = __elf_create_symbol(elf, sym);
-	if (sym)
-		elf_add_symbol(elf, sym);
-
-	return sym;
+	return elf_create_symbol(elf, name, orig->sec,
+				 GELF_ST_BIND(orig->sym.st_info),
+				 GELF_ST_TYPE(orig->sym.st_info),
+				 offset, size);
 }
 
 static struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
@@ -934,7 +943,7 @@ struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
 				      unsigned long insn_off)
 {
 	struct symbol *sym = insn_sec->sym;
-	int addend = insn_off;
+	s64 addend = insn_off;
 
 	if (!is_text_sec(insn_sec)) {
 		ERROR("bad call to %s() for data symbol %s", __func__, sym->name);
@@ -951,8 +960,6 @@ struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
 		sym = elf_create_section_symbol(elf, insn_sec);
 		if (!sym)
 			return NULL;
-
-		insn_sec->sym = sym;
 	}
 
 	return elf_init_reloc(elf, sec->rsec, reloc_idx, offset, sym, addend,
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 07fc41f574b9..c33b8fa0e3ce 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -15,6 +15,8 @@
 #include <linux/jhash.h>
 #include <arch/elf.h>
 
+#define SYM_NAME_LEN		512
+
 #ifdef LIBELF_USE_DEPRECATED
 # define elf_getshdrnum    elf_getshnum
 # define elf_getshdrstrndx elf_getshstrndx
@@ -120,7 +122,14 @@ struct section *elf_create_section_pair(struct elf *elf, const char *name,
 					size_t entsize, unsigned int nr,
 					unsigned int reloc_nr);
 
-struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, long size);
+struct symbol *elf_create_symbol(struct elf *elf, const char *name,
+				 struct section *sec, unsigned int bind,
+				 unsigned int type, unsigned long offset,
+				 size_t size);
+struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec);
+struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig,
+					size_t size);
+
 
 struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
 				      unsigned long offset,
-- 
cgit v1.2.3


From 243e96385368fc5e31da4e9927a201a27a2ae936 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:48 -0700
Subject: objtool: Generalize elf_create_section()

In preparation for the objtool klp diff subcommand, broaden the
elf_create_section() interface to give callers more control and reduce
duplication of some subtle setup logic.

While at it, make elf_create_rela_section() global so sections can be
created by the upcoming klp diff code.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c                 | 114 ++++++++++++++++++++----------------
 tools/objtool/include/objtool/elf.h |   7 ++-
 tools/objtool/orc_gen.c             |   6 +-
 3 files changed, 75 insertions(+), 52 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index d7703c848ce0..7a7e63c7153f 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -1138,51 +1138,53 @@ static int elf_add_string(struct elf *elf, struct section *strtab, const char *s
 }
 
 struct section *elf_create_section(struct elf *elf, const char *name,
-				   size_t entsize, unsigned int nr)
+				   size_t size, size_t entsize,
+				   unsigned int type, unsigned int align,
+				   unsigned int flags)
 {
 	struct section *sec, *shstrtab;
-	size_t size = entsize * nr;
 	Elf_Scn *s;
 
-	sec = malloc(sizeof(*sec));
+	if (name && find_section_by_name(elf, name)) {
+		ERROR("section '%s' already exists", name);
+		return NULL;
+	}
+
+	sec = calloc(1, sizeof(*sec));
 	if (!sec) {
-		ERROR_GLIBC("malloc");
+		ERROR_GLIBC("calloc");
 		return NULL;
 	}
-	memset(sec, 0, sizeof(*sec));
 
 	INIT_LIST_HEAD(&sec->symbol_list);
 
+	/* don't actually create the section, just the data structures */
+	if (type == SHT_NULL)
+		goto add;
+
 	s = elf_newscn(elf->elf);
 	if (!s) {
 		ERROR_ELF("elf_newscn");
 		return NULL;
 	}
 
-	sec->name = strdup(name);
-	if (!sec->name) {
-		ERROR_GLIBC("strdup");
-		return NULL;
-	}
-
 	sec->idx = elf_ndxscn(s);
 
-	sec->data = elf_newdata(s);
-	if (!sec->data) {
-		ERROR_ELF("elf_newdata");
-		return NULL;
-	}
+	if (size) {
+		sec->data = elf_newdata(s);
+		if (!sec->data) {
+			ERROR_ELF("elf_newdata");
+			return NULL;
+		}
 
-	sec->data->d_size = size;
-	sec->data->d_align = 1;
+		sec->data->d_size = size;
+		sec->data->d_align = 1;
 
-	if (size) {
-		sec->data->d_buf = malloc(size);
+		sec->data->d_buf = calloc(1, size);
 		if (!sec->data->d_buf) {
-			ERROR_GLIBC("malloc");
+			ERROR_GLIBC("calloc");
 			return NULL;
 		}
-		memset(sec->data->d_buf, 0, size);
 	}
 
 	if (!gelf_getshdr(s, &sec->sh)) {
@@ -1192,34 +1194,44 @@ struct section *elf_create_section(struct elf *elf, const char *name,
 
 	sec->sh.sh_size = size;
 	sec->sh.sh_entsize = entsize;
-	sec->sh.sh_type = SHT_PROGBITS;
-	sec->sh.sh_addralign = 1;
-	sec->sh.sh_flags = SHF_ALLOC;
-
-	/* Add section name to .shstrtab (or .strtab for Clang) */
-	shstrtab = find_section_by_name(elf, ".shstrtab");
-	if (!shstrtab)
-		shstrtab = find_section_by_name(elf, ".strtab");
-	if (!shstrtab) {
-		ERROR("can't find .shstrtab or .strtab section");
-		return NULL;
+	sec->sh.sh_type = type;
+	sec->sh.sh_addralign = align;
+	sec->sh.sh_flags = flags;
+
+	if (name) {
+		sec->name = strdup(name);
+		if (!sec->name) {
+			ERROR("strdup");
+			return NULL;
+		}
+
+		/* Add section name to .shstrtab (or .strtab for Clang) */
+		shstrtab = find_section_by_name(elf, ".shstrtab");
+		if (!shstrtab) {
+			shstrtab = find_section_by_name(elf, ".strtab");
+			if (!shstrtab) {
+				ERROR("can't find .shstrtab or .strtab");
+				return NULL;
+			}
+		}
+		sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
+		if (sec->sh.sh_name == -1)
+			return NULL;
+
+		elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
 	}
-	sec->sh.sh_name = elf_add_string(elf, shstrtab, sec->name);
-	if (sec->sh.sh_name == -1)
-		return NULL;
 
+add:
 	list_add_tail(&sec->list, &elf->sections);
 	elf_hash_add(section, &sec->hash, sec->idx);
-	elf_hash_add(section_name, &sec->name_hash, str_hash(sec->name));
 
 	mark_sec_changed(elf, sec, true);
 
 	return sec;
 }
 
-static struct section *elf_create_rela_section(struct elf *elf,
-					       struct section *sec,
-					       unsigned int reloc_nr)
+struct section *elf_create_rela_section(struct elf *elf, struct section *sec,
+					unsigned int reloc_nr)
 {
 	struct section *rsec;
 	char *rsec_name;
@@ -1232,22 +1244,23 @@ static struct section *elf_create_rela_section(struct elf *elf,
 	strcpy(rsec_name, ".rela");
 	strcat(rsec_name, sec->name);
 
-	rsec = elf_create_section(elf, rsec_name, elf_rela_size(elf), reloc_nr);
+	rsec = elf_create_section(elf, rsec_name, reloc_nr * elf_rela_size(elf),
+				  elf_rela_size(elf), SHT_RELA, elf_addr_size(elf),
+				  SHF_INFO_LINK);
 	free(rsec_name);
 	if (!rsec)
 		return NULL;
 
-	rsec->data->d_type = ELF_T_RELA;
-	rsec->sh.sh_type = SHT_RELA;
-	rsec->sh.sh_addralign = elf_addr_size(elf);
 	rsec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
 	rsec->sh.sh_info = sec->idx;
-	rsec->sh.sh_flags = SHF_INFO_LINK;
 
-	rsec->relocs = calloc(sec_num_entries(rsec), sizeof(struct reloc));
-	if (!rsec->relocs) {
-		ERROR_GLIBC("calloc");
-		return NULL;
+	if (reloc_nr) {
+		rsec->data->d_type = ELF_T_RELA;
+		rsec->relocs = calloc(sec_num_entries(rsec), sizeof(struct reloc));
+		if (!rsec->relocs) {
+			ERROR_GLIBC("calloc");
+			return NULL;
+		}
 	}
 
 	sec->rsec = rsec;
@@ -1262,7 +1275,8 @@ struct section *elf_create_section_pair(struct elf *elf, const char *name,
 {
 	struct section *sec;
 
-	sec = elf_create_section(elf, name, entsize, nr);
+	sec = elf_create_section(elf, name, nr * entsize, entsize,
+				 SHT_PROGBITS, 1, SHF_ALLOC);
 	if (!sec)
 		return NULL;
 
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index c33b8fa0e3ce..badb10926d1e 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -117,11 +117,16 @@ struct elf {
 struct elf *elf_open_read(const char *name, int flags);
 
 struct section *elf_create_section(struct elf *elf, const char *name,
-				   size_t entsize, unsigned int nr);
+				   size_t size, size_t entsize,
+				   unsigned int type, unsigned int align,
+				   unsigned int flags);
 struct section *elf_create_section_pair(struct elf *elf, const char *name,
 					size_t entsize, unsigned int nr,
 					unsigned int reloc_nr);
 
+struct section *elf_create_rela_section(struct elf *elf, struct section *sec,
+					unsigned int reloc_nr);
+
 struct symbol *elf_create_symbol(struct elf *elf, const char *name,
 				 struct section *sec, unsigned int bind,
 				 unsigned int type, unsigned long offset,
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index 6eff3d6a125c..9d380abc2ed3 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -127,7 +127,11 @@ int orc_create(struct objtool_file *file)
 		return -1;
 	}
 	orc_sec = elf_create_section(file->elf, ".orc_unwind",
-				     sizeof(struct orc_entry), nr);
+				     nr * sizeof(struct orc_entry),
+				     sizeof(struct orc_entry),
+				     SHT_PROGBITS,
+				     1,
+				     SHF_ALLOC);
 	if (!orc_sec)
 		return -1;
 
-- 
cgit v1.2.3


From 431dbabf2d9dd27cd597a9d1d4611e7ae64bf8bd Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:49 -0700
Subject: objtool: Add elf_create_data()

In preparation for the objtool klp diff subcommand, refactor
elf_add_string() by adding a new elf_add_data() helper which allows the
adding of arbitrary data to a section.

Make both interfaces global so they can be used by the upcoming klp diff
code.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c                 | 66 ++++++++++++++++++++++++++-----------
 tools/objtool/include/objtool/elf.h | 10 ++++--
 2 files changed, 54 insertions(+), 22 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 7a7e63c7153f..117a1b5915a1 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -18,10 +18,11 @@
 #include <errno.h>
 #include <linux/interval_tree_generic.h>
 #include <objtool/builtin.h>
-
 #include <objtool/elf.h>
 #include <objtool/warn.h>
 
+#define ALIGN_UP(x, align_to) (((x) + ((align_to)-1)) & ~((align_to)-1))
+
 static inline u32 str_hash(const char *str)
 {
 	return jhash(str, strlen(str), 0);
@@ -763,8 +764,6 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
 	return 0;
 }
 
-static int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
-
 struct symbol *elf_create_symbol(struct elf *elf, const char *name,
 				 struct section *sec, unsigned int bind,
 				 unsigned int type, unsigned long offset,
@@ -1100,11 +1099,9 @@ err:
 	return NULL;
 }
 
-static int elf_add_string(struct elf *elf, struct section *strtab, const char *str)
+unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str)
 {
-	Elf_Data *data;
-	Elf_Scn *s;
-	int len;
+	unsigned int offset;
 
 	if (!strtab)
 		strtab = find_section_by_name(elf, ".strtab");
@@ -1113,28 +1110,59 @@ static int elf_add_string(struct elf *elf, struct section *strtab, const char *s
 		return -1;
 	}
 
-	s = elf_getscn(elf->elf, strtab->idx);
+	if (!strtab->sh.sh_addralign) {
+		ERROR("'%s': invalid sh_addralign", strtab->name);
+		return -1;
+	}
+
+	offset = ALIGN_UP(strtab->sh.sh_size, strtab->sh.sh_addralign);
+
+	if (!elf_add_data(elf, strtab, str, strlen(str) + 1))
+		return -1;
+
+	return offset;
+}
+
+void *elf_add_data(struct elf *elf, struct section *sec, const void *data, size_t size)
+{
+	unsigned long offset;
+	Elf_Scn *s;
+
+	if (!sec->sh.sh_addralign) {
+		ERROR("'%s': invalid sh_addralign", sec->name);
+		return NULL;
+	}
+
+	s = elf_getscn(elf->elf, sec->idx);
 	if (!s) {
 		ERROR_ELF("elf_getscn");
-		return -1;
+		return NULL;
 	}
 
-	data = elf_newdata(s);
-	if (!data) {
+	sec->data = elf_newdata(s);
+	if (!sec->data) {
 		ERROR_ELF("elf_newdata");
-		return -1;
+		return NULL;
 	}
 
-	data->d_buf = strdup(str);
-	data->d_size = strlen(str) + 1;
-	data->d_align = 1;
+	sec->data->d_buf = calloc(1, size);
+	if (!sec->data->d_buf) {
+		ERROR_GLIBC("calloc");
+		return NULL;
+	}
 
-	len = strtab->sh.sh_size;
-	strtab->sh.sh_size += data->d_size;
+	if (data)
+		memcpy(sec->data->d_buf, data, size);
 
-	mark_sec_changed(elf, strtab, true);
+	sec->data->d_size = size;
+	sec->data->d_align = 1;
+
+	offset = ALIGN_UP(sec->sh.sh_size, sec->sh.sh_addralign);
+	sec->sh.sh_size = offset + size;
+
+	mark_sec_changed(elf, sec, true);
 
-	return len;
+	return sec->data->d_buf;
 }
 
 struct section *elf_create_section(struct elf *elf, const char *name,
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index badb10926d1e..0d9aeefb6d12 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -135,6 +135,10 @@ struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec);
 struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig,
 					size_t size);
 
+void *elf_add_data(struct elf *elf, struct section *sec, const void *data,
+		   size_t size);
+
+unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
 
 struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
 				      unsigned long offset,
@@ -148,9 +152,9 @@ struct reloc *elf_init_reloc_data_sym(struct elf *elf, struct section *sec,
 				      struct symbol *sym,
 				      s64 addend);
 
-int elf_write_insn(struct elf *elf, struct section *sec,
-		   unsigned long offset, unsigned int len,
-		   const char *insn);
+int elf_write_insn(struct elf *elf, struct section *sec, unsigned long offset,
+		   unsigned int len, const char *insn);
+
 int elf_write(struct elf *elf);
 void elf_close(struct elf *elf);
 
-- 
cgit v1.2.3


From 2c05ca02621837af7cd8fab6ae7421b9cd5dff6e Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:50 -0700
Subject: objtool: Add elf_create_reloc() and elf_init_reloc()

elf_create_rela_section() is quite limited in that it requires the
caller to know how many relocations need to be allocated up front.

In preparation for the objtool klp diff subcommand, allow an arbitrary
number of relocations to be created and initialized on demand after
section creation.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/elf.c                 | 170 +++++++++++++++++++++++++++++++++---
 tools/objtool/include/objtool/elf.h |   9 ++
 2 files changed, 165 insertions(+), 14 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 117a1b5915a1..8d01fc3b4f67 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -22,6 +22,8 @@
 #include <objtool/warn.h>
 
 #define ALIGN_UP(x, align_to) (((x) + ((align_to)-1)) & ~((align_to)-1))
+#define ALIGN_UP_POW2(x) (1U << ((8 * sizeof(x)) - __builtin_clz((x) - 1U)))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
 
 static inline u32 str_hash(const char *str)
 {
@@ -899,10 +901,9 @@ elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, size_t size)
 				 offset, size);
 }
 
-static struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
-				    unsigned int reloc_idx,
-				    unsigned long offset, struct symbol *sym,
-				    s64 addend, unsigned int type)
+struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
+			     unsigned int reloc_idx, unsigned long offset,
+			     struct symbol *sym, s64 addend, unsigned int type)
 {
 	struct reloc *reloc, empty = { 0 };
 
@@ -1004,12 +1005,16 @@ static int read_relocs(struct elf *elf)
 
 		rsec->base->rsec = rsec;
 
-		nr_reloc = 0;
+		/* nr_alloc_relocs=0: libelf owns d_buf */
+		rsec->nr_alloc_relocs = 0;
+
 		rsec->relocs = calloc(sec_num_entries(rsec), sizeof(*reloc));
 		if (!rsec->relocs) {
 			ERROR_GLIBC("calloc");
 			return -1;
 		}
+
+		nr_reloc = 0;
 		for (i = 0; i < sec_num_entries(rsec); i++) {
 			reloc = &rsec->relocs[i];
 
@@ -1258,8 +1263,116 @@ add:
 	return sec;
 }
 
+static int elf_alloc_reloc(struct elf *elf, struct section *rsec)
+{
+	struct reloc *old_relocs, *old_relocs_end, *new_relocs;
+	unsigned int nr_relocs_old = sec_num_entries(rsec);
+	unsigned int nr_relocs_new = nr_relocs_old + 1;
+	unsigned long nr_alloc;
+	struct symbol *sym;
+
+	if (!rsec->data) {
+		rsec->data = elf_newdata(elf_getscn(elf->elf, rsec->idx));
+		if (!rsec->data) {
+			ERROR_ELF("elf_newdata");
+			return -1;
+		}
+
+		rsec->data->d_align = 1;
+		rsec->data->d_type = ELF_T_RELA;
+		rsec->data->d_buf = NULL;
+	}
+
+	rsec->data->d_size = nr_relocs_new * elf_rela_size(elf);
+	rsec->sh.sh_size   = rsec->data->d_size;
+
+	nr_alloc = MAX(64, ALIGN_UP_POW2(nr_relocs_new));
+	if (nr_alloc <= rsec->nr_alloc_relocs)
+		return 0;
+
+	if (rsec->data->d_buf && !rsec->nr_alloc_relocs) {
+		void *orig_buf = rsec->data->d_buf;
+
+		/*
+		 * The original d_buf is owned by libelf so it can't be
+		 * realloced.
+		 */
+		rsec->data->d_buf = malloc(nr_alloc * elf_rela_size(elf));
+		if (!rsec->data->d_buf) {
+			ERROR_GLIBC("malloc");
+			return -1;
+		}
+		memcpy(rsec->data->d_buf, orig_buf,
+		       nr_relocs_old * elf_rela_size(elf));
+	} else {
+		rsec->data->d_buf = realloc(rsec->data->d_buf,
+					    nr_alloc * elf_rela_size(elf));
+		if (!rsec->data->d_buf) {
+			ERROR_GLIBC("realloc");
+			return -1;
+		}
+	}
+
+	rsec->nr_alloc_relocs = nr_alloc;
+
+	old_relocs = rsec->relocs;
+	new_relocs = calloc(nr_alloc, sizeof(struct reloc));
+	if (!new_relocs) {
+		ERROR_GLIBC("calloc");
+		return -1;
+	}
+
+	if (!old_relocs)
+		goto done;
+
+	/*
+	 * The struct reloc's address has changed.  Update all the symbols and
+	 * relocs which reference it.
+	 */
+
+	old_relocs_end = &old_relocs[nr_relocs_old];
+	for_each_sym(elf, sym) {
+		struct reloc *reloc;
+
+		reloc = sym->relocs;
+		if (!reloc)
+			continue;
+
+		if (reloc >= old_relocs && reloc < old_relocs_end)
+			sym->relocs = &new_relocs[reloc - old_relocs];
+
+		while (1) {
+			struct reloc *next_reloc = sym_next_reloc(reloc);
+
+			if (!next_reloc)
+				break;
+
+			if (next_reloc >= old_relocs && next_reloc < old_relocs_end)
+				set_sym_next_reloc(reloc, &new_relocs[next_reloc - old_relocs]);
+
+			reloc = next_reloc;
+		}
+	}
+
+	memcpy(new_relocs, old_relocs, nr_relocs_old * sizeof(struct reloc));
+
+	for (int i = 0; i < nr_relocs_old; i++) {
+		struct reloc *old = &old_relocs[i];
+		struct reloc *new = &new_relocs[i];
+		u32 key = reloc_hash(old);
+
+		elf_hash_del(reloc, &old->hash, key);
+		elf_hash_add(reloc, &new->hash, key);
+	}
+
+	free(old_relocs);
+done:
+	rsec->relocs = new_relocs;
+	return 0;
+}
+
 struct section *elf_create_rela_section(struct elf *elf, struct section *sec,
-					unsigned int reloc_nr)
+					unsigned int nr_relocs)
 {
 	struct section *rsec;
 	char *rsec_name;
@@ -1272,34 +1385,63 @@ struct section *elf_create_rela_section(struct elf *elf, struct section *sec,
 	strcpy(rsec_name, ".rela");
 	strcat(rsec_name, sec->name);
 
-	rsec = elf_create_section(elf, rsec_name, reloc_nr * elf_rela_size(elf),
+	rsec = elf_create_section(elf, rsec_name, nr_relocs * elf_rela_size(elf),
 				  elf_rela_size(elf), SHT_RELA, elf_addr_size(elf),
 				  SHF_INFO_LINK);
 	free(rsec_name);
 	if (!rsec)
 		return NULL;
 
-	rsec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
-	rsec->sh.sh_info = sec->idx;
-
-	if (reloc_nr) {
+	if (nr_relocs) {
 		rsec->data->d_type = ELF_T_RELA;
-		rsec->relocs = calloc(sec_num_entries(rsec), sizeof(struct reloc));
+
+		rsec->nr_alloc_relocs = nr_relocs;
+		rsec->relocs = calloc(nr_relocs, sizeof(struct reloc));
 		if (!rsec->relocs) {
 			ERROR_GLIBC("calloc");
 			return NULL;
 		}
 	}
 
+	rsec->sh.sh_link = find_section_by_name(elf, ".symtab")->idx;
+	rsec->sh.sh_info = sec->idx;
+
 	sec->rsec = rsec;
 	rsec->base = sec;
 
 	return rsec;
 }
 
+struct reloc *elf_create_reloc(struct elf *elf, struct section *sec,
+			       unsigned long offset,
+			       struct symbol *sym, s64 addend,
+			       unsigned int type)
+{
+	struct section *rsec = sec->rsec;
+
+	if (!rsec) {
+		rsec = elf_create_rela_section(elf, sec, 0);
+		if (!rsec)
+			return NULL;
+	}
+
+	if (find_reloc_by_dest(elf, sec, offset)) {
+		ERROR_FUNC(sec, offset, "duplicate reloc");
+		return NULL;
+	}
+
+	if (elf_alloc_reloc(elf, rsec))
+		return NULL;
+
+	mark_sec_changed(elf, rsec, true);
+
+	return elf_init_reloc(elf, rsec, sec_num_entries(rsec) - 1, offset, sym,
+			      addend, type);
+}
+
 struct section *elf_create_section_pair(struct elf *elf, const char *name,
 					size_t entsize, unsigned int nr,
-					unsigned int reloc_nr)
+					unsigned int nr_relocs)
 {
 	struct section *sec;
 
@@ -1308,7 +1450,7 @@ struct section *elf_create_section_pair(struct elf *elf, const char *name,
 	if (!sec)
 		return NULL;
 
-	if (!elf_create_rela_section(elf, sec, reloc_nr))
+	if (!elf_create_rela_section(elf, sec, nr_relocs))
 		return NULL;
 
 	return sec;
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 0d9aeefb6d12..999fd9369cf5 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -47,6 +47,7 @@ struct section {
 	int idx;
 	bool _changed, text, rodata, noinstr, init, truncate;
 	struct reloc *relocs;
+	unsigned long nr_alloc_relocs;
 };
 
 struct symbol {
@@ -140,6 +141,14 @@ void *elf_add_data(struct elf *elf, struct section *sec, const void *data,
 
 unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str);
 
+struct reloc *elf_create_reloc(struct elf *elf, struct section *sec,
+			       unsigned long offset, struct symbol *sym,
+			       s64 addend, unsigned int type);
+
+struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
+			     unsigned int reloc_idx, unsigned long offset,
+			     struct symbol *sym, s64 addend, unsigned int type);
+
 struct reloc *elf_init_reloc_text_sym(struct elf *elf, struct section *sec,
 				      unsigned long offset,
 				      unsigned int reloc_idx,
-- 
cgit v1.2.3


From 03c19a99ee69f4680d7da11c164ac655b4946b99 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:51 -0700
Subject: objtool: Add elf_create_file()

Add interface to enable the creation of a new ELF file.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/builtin-check.c       |   2 +-
 tools/objtool/elf.c                 | 144 +++++++++++++++++++++++++++++++++++-
 tools/objtool/include/objtool/elf.h |   5 +-
 3 files changed, 147 insertions(+), 4 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index fc91bc5cdb6b..99697141964a 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -329,5 +329,5 @@ int objtool_run(int argc, const char **argv)
 	if (!opts.dryrun && file->elf->changed && elf_write(file->elf))
 		return 1;
 
-	return 0;
+	return elf_close(file->elf);
 }
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 8d01fc3b4f67..6095baba8e9c 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -16,6 +16,7 @@
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
+#include <libgen.h>
 #include <linux/interval_tree_generic.h>
 #include <objtool/builtin.h>
 #include <objtool/elf.h>
@@ -1067,6 +1068,12 @@ struct elf *elf_open_read(const char *name, int flags)
 		goto err;
 	}
 
+	elf->name = strdup(name);
+	if (!elf->name) {
+		ERROR_GLIBC("strdup");
+		return NULL;
+	}
+
 	if ((flags & O_ACCMODE) == O_RDONLY)
 		cmd = ELF_C_READ_MMAP;
 	else if ((flags & O_ACCMODE) == O_RDWR)
@@ -1104,6 +1111,137 @@ err:
 	return NULL;
 }
 
+struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name)
+{
+	struct section *null, *symtab, *strtab, *shstrtab;
+	char *dir, *base, *tmp_name;
+	struct symbol *sym;
+	struct elf *elf;
+
+	elf_version(EV_CURRENT);
+
+	elf = calloc(1, sizeof(*elf));
+	if (!elf) {
+		ERROR_GLIBC("calloc");
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&elf->sections);
+
+	dir = strdup(name);
+	if (!dir) {
+		ERROR_GLIBC("strdup");
+		return NULL;
+	}
+
+	dir = dirname(dir);
+
+	base = strdup(name);
+	if (!base) {
+		ERROR_GLIBC("strdup");
+		return NULL;
+	}
+
+	base = basename(base);
+
+	tmp_name = malloc(256);
+	if (!tmp_name) {
+		ERROR_GLIBC("malloc");
+		return NULL;
+	}
+
+	snprintf(tmp_name, 256, "%s/%s.XXXXXX", dir, base);
+
+	elf->fd = mkstemp(tmp_name);
+	if (elf->fd == -1) {
+		ERROR_GLIBC("can't create tmp file");
+		exit(1);
+	}
+
+	elf->tmp_name = tmp_name;
+
+	elf->name = strdup(name);
+	if (!elf->name) {
+		ERROR_GLIBC("strdup");
+		return NULL;
+	}
+
+	elf->elf = elf_begin(elf->fd, ELF_C_WRITE, NULL);
+	if (!elf->elf) {
+		ERROR_ELF("elf_begin");
+		return NULL;
+	}
+
+	if (!gelf_newehdr(elf->elf, ELFCLASS64)) {
+		ERROR_ELF("gelf_newehdr");
+		return NULL;
+	}
+
+	memcpy(&elf->ehdr, ehdr, sizeof(elf->ehdr));
+
+	if (!gelf_update_ehdr(elf->elf, &elf->ehdr)) {
+		ERROR_ELF("gelf_update_ehdr");
+		return NULL;
+	}
+
+	if (!elf_alloc_hash(section,		1000) ||
+	    !elf_alloc_hash(section_name,	1000) ||
+	    !elf_alloc_hash(symbol,		10000) ||
+	    !elf_alloc_hash(symbol_name,	10000) ||
+	    !elf_alloc_hash(reloc,		100000))
+		return NULL;
+
+	null		= elf_create_section(elf, NULL, 0, 0, SHT_NULL, 0, 0);
+	shstrtab	= elf_create_section(elf, NULL, 0, 0, SHT_STRTAB, 1, 0);
+	strtab		= elf_create_section(elf, NULL, 0, 0, SHT_STRTAB, 1, 0);
+
+	if (!null || !shstrtab || !strtab)
+		return NULL;
+
+	null->name	= "";
+	shstrtab->name	= ".shstrtab";
+	strtab->name	= ".strtab";
+
+	null->sh.sh_name	= elf_add_string(elf, shstrtab, null->name);
+	shstrtab->sh.sh_name	= elf_add_string(elf, shstrtab, shstrtab->name);
+	strtab->sh.sh_name	= elf_add_string(elf, shstrtab, strtab->name);
+
+	if (null->sh.sh_name == -1 || shstrtab->sh.sh_name == -1 || strtab->sh.sh_name == -1)
+		return NULL;
+
+	elf_hash_add(section_name, &null->name_hash,		str_hash(null->name));
+	elf_hash_add(section_name, &strtab->name_hash,		str_hash(strtab->name));
+	elf_hash_add(section_name, &shstrtab->name_hash,	str_hash(shstrtab->name));
+
+	if (elf_add_string(elf, strtab, "") == -1)
+		return NULL;
+
+	symtab = elf_create_section(elf, ".symtab", 0x18, 0x18, SHT_SYMTAB, 0x8, 0);
+	if (!symtab)
+		return NULL;
+
+	symtab->sh.sh_link = strtab->idx;
+	symtab->sh.sh_info = 1;
+
+	elf->ehdr.e_shstrndx = shstrtab->idx;
+	if (!gelf_update_ehdr(elf->elf, &elf->ehdr)) {
+		ERROR_ELF("gelf_update_ehdr");
+		return NULL;
+	}
+
+	sym = calloc(1, sizeof(*sym));
+	if (!sym) {
+		ERROR_GLIBC("calloc");
+		return NULL;
+	}
+
+	sym->name = "";
+	sym->sec = null;
+	elf_add_symbol(elf, sym);
+
+	return elf;
+}
+
 unsigned int elf_add_string(struct elf *elf, struct section *strtab, const char *str)
 {
 	unsigned int offset;
@@ -1568,7 +1706,7 @@ int elf_write(struct elf *elf)
 	return 0;
 }
 
-void elf_close(struct elf *elf)
+int elf_close(struct elf *elf)
 {
 	if (elf->elf)
 		elf_end(elf->elf);
@@ -1576,8 +1714,12 @@ void elf_close(struct elf *elf)
 	if (elf->fd > 0)
 		close(elf->fd);
 
+	if (elf->tmp_name && rename(elf->tmp_name, elf->name))
+		return -1;
+
 	/*
 	 * NOTE: All remaining allocations are leaked on purpose.  Objtool is
 	 * about to exit anyway.
 	 */
+	return 0;
 }
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 999fd9369cf5..9f135c262659 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -94,7 +94,7 @@ struct elf {
 	GElf_Ehdr ehdr;
 	int fd;
 	bool changed;
-	const char *name;
+	const char *name, *tmp_name;
 	unsigned int num_files;
 	struct list_head sections;
 	unsigned long num_relocs;
@@ -116,6 +116,7 @@ struct elf {
 };
 
 struct elf *elf_open_read(const char *name, int flags);
+struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name);
 
 struct section *elf_create_section(struct elf *elf, const char *name,
 				   size_t size, size_t entsize,
@@ -165,7 +166,7 @@ int elf_write_insn(struct elf *elf, struct section *sec, unsigned long offset,
 		   unsigned int len, const char *insn);
 
 int elf_write(struct elf *elf);
-void elf_close(struct elf *elf);
+int elf_close(struct elf *elf);
 
 struct section *find_section_by_name(const struct elf *elf, const char *name);
 struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
-- 
cgit v1.2.3


From 3b92486fa1a905cf4be81c0b65961f547fcf7be3 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:52 -0700
Subject: objtool: Add annotype() helper

... for reading annotation types.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/arch/loongarch/orc.c         |  1 -
 tools/objtool/arch/powerpc/decode.c        |  1 -
 tools/objtool/arch/x86/decode.c            |  1 -
 tools/objtool/arch/x86/orc.c               |  1 -
 tools/objtool/check.c                      |  5 +----
 tools/objtool/include/objtool/elf.h        | 13 +++++++++++++
 tools/objtool/include/objtool/endianness.h |  9 ++++-----
 tools/objtool/orc_dump.c                   |  1 -
 tools/objtool/orc_gen.c                    |  1 -
 tools/objtool/special.c                    |  1 -
 10 files changed, 18 insertions(+), 16 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/arch/loongarch/orc.c b/tools/objtool/arch/loongarch/orc.c
index b58c5ff443c9..ffd3a3c858ae 100644
--- a/tools/objtool/arch/loongarch/orc.c
+++ b/tools/objtool/arch/loongarch/orc.c
@@ -5,7 +5,6 @@
 #include <objtool/check.h>
 #include <objtool/orc.h>
 #include <objtool/warn.h>
-#include <objtool/endianness.h>
 
 int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi, struct instruction *insn)
 {
diff --git a/tools/objtool/arch/powerpc/decode.c b/tools/objtool/arch/powerpc/decode.c
index d4cb02120a6b..3a9b748216ed 100644
--- a/tools/objtool/arch/powerpc/decode.c
+++ b/tools/objtool/arch/powerpc/decode.c
@@ -7,7 +7,6 @@
 #include <objtool/arch.h>
 #include <objtool/warn.h>
 #include <objtool/builtin.h>
-#include <objtool/endianness.h>
 
 int arch_ftrace_match(const char *name)
 {
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 6bb46d998153..b2c320f701f9 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -19,7 +19,6 @@
 #include <objtool/elf.h>
 #include <objtool/arch.h>
 #include <objtool/warn.h>
-#include <objtool/endianness.h>
 #include <objtool/builtin.h>
 #include <arch/elf.h>
 
diff --git a/tools/objtool/arch/x86/orc.c b/tools/objtool/arch/x86/orc.c
index 7176b9ec5b05..735e150ca6b7 100644
--- a/tools/objtool/arch/x86/orc.c
+++ b/tools/objtool/arch/x86/orc.c
@@ -5,7 +5,6 @@
 #include <objtool/check.h>
 #include <objtool/orc.h>
 #include <objtool/warn.h>
-#include <objtool/endianness.h>
 
 int init_orc_entry(struct orc_entry *orc, struct cfi_state *cfi, struct instruction *insn)
 {
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 65a359cbf4ea..13ccfe0c7eba 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -14,7 +14,6 @@
 #include <objtool/check.h>
 #include <objtool/special.h>
 #include <objtool/warn.h>
-#include <objtool/endianness.h>
 
 #include <linux/objtool_types.h>
 #include <linux/hashtable.h>
@@ -2273,9 +2272,7 @@ static int read_annotate(struct objtool_file *file,
 	}
 
 	for_each_reloc(sec->rsec, reloc) {
-		type = *(u32 *)(sec->data->d_buf + (reloc_idx(reloc) * sec->sh.sh_entsize) + 4);
-		type = bswap_if_needed(file->elf, type);
-
+		type = annotype(file->elf, sec, reloc);
 		offset = reloc->sym->offset + reloc_addend(reloc);
 		insn = find_insn(file, reloc->sym->sec, offset);
 
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 9f135c262659..814cfc0bbf16 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -13,10 +13,14 @@
 #include <linux/hashtable.h>
 #include <linux/rbtree.h>
 #include <linux/jhash.h>
+
+#include <objtool/endianness.h>
 #include <arch/elf.h>
 
 #define SYM_NAME_LEN		512
 
+#define bswap_if_needed(elf, val) __bswap_if_needed(&elf->ehdr, val)
+
 #ifdef LIBELF_USE_DEPRECATED
 # define elf_getshdrnum    elf_getshnum
 # define elf_getshdrstrndx elf_getshstrndx
@@ -401,6 +405,15 @@ static inline void set_reloc_type(struct elf *elf, struct reloc *reloc, unsigned
 	mark_sec_changed(elf, reloc->sec, true);
 }
 
+static inline unsigned int annotype(struct elf *elf, struct section *sec,
+				    struct reloc *reloc)
+{
+	unsigned int type;
+
+	type = *(u32 *)(sec->data->d_buf + (reloc_idx(reloc) * 8) + 4);
+	return bswap_if_needed(elf, type);
+}
+
 #define RELOC_JUMP_TABLE_BIT 1UL
 
 /* Does reloc mark the beginning of a jump table? */
diff --git a/tools/objtool/include/objtool/endianness.h b/tools/objtool/include/objtool/endianness.h
index 4d2aa9b0fe2f..aebcd2338668 100644
--- a/tools/objtool/include/objtool/endianness.h
+++ b/tools/objtool/include/objtool/endianness.h
@@ -4,7 +4,6 @@
 
 #include <linux/kernel.h>
 #include <endian.h>
-#include <objtool/elf.h>
 
 /*
  * Does a byte swap if target file endianness doesn't match the host, i.e. cross
@@ -12,16 +11,16 @@
  * To be used for multi-byte values conversion, which are read from / about
  * to be written to a target native endianness ELF file.
  */
-static inline bool need_bswap(struct elf *elf)
+static inline bool need_bswap(GElf_Ehdr *ehdr)
 {
 	return (__BYTE_ORDER == __LITTLE_ENDIAN) ^
-	       (elf->ehdr.e_ident[EI_DATA] == ELFDATA2LSB);
+	       (ehdr->e_ident[EI_DATA] == ELFDATA2LSB);
 }
 
-#define bswap_if_needed(elf, val)					\
+#define __bswap_if_needed(ehdr, val)					\
 ({									\
 	__typeof__(val) __ret;						\
-	bool __need_bswap = need_bswap(elf);				\
+	bool __need_bswap = need_bswap(ehdr);				\
 	switch (sizeof(val)) {						\
 	case 8:								\
 		__ret = __need_bswap ? bswap_64(val) : (val); break;	\
diff --git a/tools/objtool/orc_dump.c b/tools/objtool/orc_dump.c
index 1dd9fc18fe62..5a979f52425a 100644
--- a/tools/objtool/orc_dump.c
+++ b/tools/objtool/orc_dump.c
@@ -8,7 +8,6 @@
 #include <objtool/objtool.h>
 #include <objtool/orc.h>
 #include <objtool/warn.h>
-#include <objtool/endianness.h>
 
 int orc_dump(const char *filename)
 {
diff --git a/tools/objtool/orc_gen.c b/tools/objtool/orc_gen.c
index 9d380abc2ed3..1045e1380ffd 100644
--- a/tools/objtool/orc_gen.c
+++ b/tools/objtool/orc_gen.c
@@ -12,7 +12,6 @@
 #include <objtool/check.h>
 #include <objtool/orc.h>
 #include <objtool/warn.h>
-#include <objtool/endianness.h>
 
 struct orc_list_entry {
 	struct list_head list;
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index fc2cf8dba1c0..e262af917143 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -15,7 +15,6 @@
 #include <objtool/builtin.h>
 #include <objtool/special.h>
 #include <objtool/warn.h>
-#include <objtool/endianness.h>
 
 struct special_entry {
 	const char *sec;
-- 
cgit v1.2.3


From 0d83da43b1e1c8ce19f2bb10f54a0fdf795364f7 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:57 -0700
Subject: objtool/klp: Add --checksum option to generate per-function checksums

In preparation for the objtool klp diff subcommand, add a command-line
option to generate a unique checksum for each function.  This will
enable detection of functions which have changed between two versions of
an object file.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/Makefile                         |  38 ++++---
 tools/objtool/builtin-check.c                  |  11 +-
 tools/objtool/check.c                          | 141 ++++++++++++++++++++++++-
 tools/objtool/elf.c                            |  46 +++++++-
 tools/objtool/include/objtool/builtin.h        |   5 +-
 tools/objtool/include/objtool/check.h          |   5 +-
 tools/objtool/include/objtool/checksum.h       |  42 ++++++++
 tools/objtool/include/objtool/checksum_types.h |  25 +++++
 tools/objtool/include/objtool/elf.h            |   4 +-
 9 files changed, 289 insertions(+), 28 deletions(-)
 create mode 100644 tools/objtool/include/objtool/checksum.h
 create mode 100644 tools/objtool/include/objtool/checksum_types.h

(limited to 'tools/objtool')

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index fc82d47f2b9a..958761c05b7c 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -2,6 +2,27 @@
 include ../scripts/Makefile.include
 include ../scripts/Makefile.arch
 
+ifeq ($(SRCARCH),x86)
+	BUILD_ORC    := y
+	ARCH_HAS_KLP := y
+endif
+
+ifeq ($(SRCARCH),loongarch)
+	BUILD_ORC	   := y
+endif
+
+ifeq ($(ARCH_HAS_KLP),y)
+	HAVE_XXHASH = $(shell echo "int main() {}" | \
+		      $(HOSTCC) -xc - -o /dev/null -lxxhash 2> /dev/null && echo y || echo n)
+	ifeq ($(HAVE_XXHASH),y)
+		LIBXXHASH_CFLAGS := $(shell $(HOSTPKG_CONFIG) libxxhash --cflags 2>/dev/null) \
+				    -DBUILD_KLP
+		LIBXXHASH_LIBS   := $(shell $(HOSTPKG_CONFIG) libxxhash --libs 2>/dev/null || echo -lxxhash)
+	endif
+endif
+
+export BUILD_ORC
+
 ifeq ($(srctree),)
 srctree := $(patsubst %/,%,$(dir $(CURDIR)))
 srctree := $(patsubst %/,%,$(dir $(srctree)))
@@ -36,10 +57,10 @@ INCLUDES := -I$(srctree)/tools/include \
 	    -I$(srctree)/tools/objtool/arch/$(SRCARCH)/include \
 	    -I$(LIBSUBCMD_OUTPUT)/include
 
-OBJTOOL_CFLAGS  := -std=gnu11 -fomit-frame-pointer -O2 -g \
-		   $(WARNINGS) $(INCLUDES) $(LIBELF_FLAGS) $(HOSTCFLAGS)
+OBJTOOL_CFLAGS  := -std=gnu11 -fomit-frame-pointer -O2 -g $(WARNINGS)	\
+		   $(INCLUDES) $(LIBELF_FLAGS) $(LIBXXHASH_CFLAGS) $(HOSTCFLAGS)
 
-OBJTOOL_LDFLAGS := $(LIBSUBCMD) $(LIBELF_LIBS) $(HOSTLDFLAGS)
+OBJTOOL_LDFLAGS := $(LIBSUBCMD) $(LIBELF_LIBS) $(LIBXXHASH_LIBS) $(HOSTLDFLAGS)
 
 # Allow old libelf to be used:
 elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(HOSTCC) $(OBJTOOL_CFLAGS) -x c -E - 2>/dev/null | grep elf_getshdr)
@@ -51,17 +72,6 @@ HOST_OVERRIDES := CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)"
 AWK = awk
 MKDIR = mkdir
 
-BUILD_ORC := n
-
-ifeq ($(SRCARCH),x86)
-	BUILD_ORC := y
-endif
-
-ifeq ($(SRCARCH),loongarch)
-	BUILD_ORC := y
-endif
-
-export BUILD_ORC
 export srctree OUTPUT CFLAGS SRCARCH AWK
 include $(srctree)/tools/build/Makefile.include
 
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 99697141964a..14daa1357c8b 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -73,6 +73,7 @@ static int parse_hacks(const struct option *opt, const char *str, int unset)
 
 static const struct option check_options[] = {
 	OPT_GROUP("Actions:"),
+	OPT_BOOLEAN(0,		 "checksum", &opts.checksum, "generate per-function checksums"),
 	OPT_BOOLEAN(0,		 "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
 	OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
 	OPT_BOOLEAN('i',	 "ibt", &opts.ibt, "validate and annotate IBT"),
@@ -160,7 +161,15 @@ static bool opts_valid(void)
 		return false;
 	}
 
-	if (opts.hack_jump_label	||
+#ifndef BUILD_KLP
+	if (opts.checksum) {
+		ERROR("--checksum not supported; install xxhash-devel and recompile");
+		return false;
+	}
+#endif
+
+	if (opts.checksum		||
+	    opts.hack_jump_label	||
 	    opts.hack_noinstr		||
 	    opts.ibt			||
 	    opts.mcount			||
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 13ccfe0c7eba..f5adbd23c42d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -14,6 +14,7 @@
 #include <objtool/check.h>
 #include <objtool/special.h>
 #include <objtool/warn.h>
+#include <objtool/checksum.h>
 
 #include <linux/objtool_types.h>
 #include <linux/hashtable.h>
@@ -971,6 +972,59 @@ static int create_direct_call_sections(struct objtool_file *file)
 	return 0;
 }
 
+#ifdef BUILD_KLP
+static int create_sym_checksum_section(struct objtool_file *file)
+{
+	struct section *sec;
+	struct symbol *sym;
+	unsigned int idx = 0;
+	struct sym_checksum *checksum;
+	size_t entsize = sizeof(struct sym_checksum);
+
+	sec = find_section_by_name(file->elf, ".discard.sym_checksum");
+	if (sec) {
+		if (!opts.dryrun)
+			WARN("file already has .discard.sym_checksum section, skipping");
+
+		return 0;
+	}
+
+	for_each_sym(file->elf, sym)
+		if (sym->csum.checksum)
+			idx++;
+
+	if (!idx)
+		return 0;
+
+	sec = elf_create_section_pair(file->elf, ".discard.sym_checksum", entsize,
+				      idx, idx);
+	if (!sec)
+		return -1;
+
+	idx = 0;
+	for_each_sym(file->elf, sym) {
+		if (!sym->csum.checksum)
+			continue;
+
+		if (!elf_init_reloc(file->elf, sec->rsec, idx, idx * entsize,
+				    sym, 0, R_TEXT64))
+			return -1;
+
+		checksum = (struct sym_checksum *)sec->data->d_buf + idx;
+		checksum->addr = 0; /* reloc */
+		checksum->checksum = sym->csum.checksum;
+
+		mark_sec_changed(file->elf, sec, true);
+
+		idx++;
+	}
+
+	return 0;
+}
+#else
+static int create_sym_checksum_section(struct objtool_file *file) { return -EINVAL; }
+#endif
+
 /*
  * Warnings shouldn't be reported for ignored functions.
  */
@@ -1748,6 +1802,7 @@ static int handle_group_alt(struct objtool_file *file,
 		nop->type = INSN_NOP;
 		nop->sym = orig_insn->sym;
 		nop->alt_group = new_alt_group;
+		nop->fake = 1;
 	}
 
 	if (!special_alt->new_len) {
@@ -2517,6 +2572,14 @@ static void mark_holes(struct objtool_file *file)
 	}
 }
 
+static bool validate_branch_enabled(void)
+{
+	return opts.stackval ||
+	       opts.orc ||
+	       opts.uaccess ||
+	       opts.checksum;
+}
+
 static int decode_sections(struct objtool_file *file)
 {
 	mark_rodata(file);
@@ -2545,8 +2608,7 @@ static int decode_sections(struct objtool_file *file)
 	 * Must be before add_jump_destinations(), which depends on 'func'
 	 * being set for alternatives, to enable proper sibling call detection.
 	 */
-	if (opts.stackval || opts.orc || opts.uaccess || opts.noinstr ||
-	    opts.hack_jump_label) {
+	if (validate_branch_enabled() || opts.noinstr || opts.hack_jump_label) {
 		if (add_special_section_alts(file))
 			return -1;
 	}
@@ -3518,6 +3580,50 @@ static bool skip_alt_group(struct instruction *insn)
 	return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
 }
 
+static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
+				 struct instruction *insn)
+{
+	struct reloc *reloc = insn_reloc(file, insn);
+	unsigned long offset;
+	struct symbol *sym;
+
+	if (insn->fake)
+		return;
+
+	checksum_update(func, insn, insn->sec->data->d_buf + insn->offset, insn->len);
+
+	if (!reloc) {
+		struct symbol *call_dest = insn_call_dest(insn);
+
+		if (call_dest)
+			checksum_update(func, insn, call_dest->demangled_name,
+					strlen(call_dest->demangled_name));
+		return;
+	}
+
+	sym = reloc->sym;
+	offset = arch_insn_adjusted_addend(insn, reloc);
+
+	if (is_string_sec(sym->sec)) {
+		char *str;
+
+		str = sym->sec->data->d_buf + sym->offset + offset;
+		checksum_update(func, insn, str, strlen(str));
+		return;
+	}
+
+	if (is_sec_sym(sym)) {
+		sym = find_symbol_containing(reloc->sym->sec, offset);
+		if (!sym)
+			return;
+
+		offset -= sym->offset;
+	}
+
+	checksum_update(func, insn, sym->demangled_name, strlen(sym->demangled_name));
+	checksum_update(func, insn, &offset, sizeof(offset));
+}
+
 /*
  * Follow the branch starting at the given instruction, and recursively follow
  * any other branches (jumps).  Meanwhile, track the frame pointer state at
@@ -3538,6 +3644,9 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 	while (1) {
 		next_insn = next_insn_to_validate(file, insn);
 
+		if (opts.checksum && func && insn->sec)
+			checksum_update_insn(file, func, insn);
+
 		if (func && insn_func(insn) && func != insn_func(insn)->pfunc) {
 			/* Ignore KCFI type preambles, which always fall through */
 			if (is_prefix_func(func))
@@ -3787,7 +3896,13 @@ static int validate_unwind_hint(struct objtool_file *file,
 				  struct insn_state *state)
 {
 	if (insn->hint && !insn->visited) {
-		int ret = validate_branch(file, insn_func(insn), insn, *state);
+		struct symbol *func = insn_func(insn);
+		int ret;
+
+		if (opts.checksum)
+			checksum_init(func);
+
+		ret = validate_branch(file, func, insn, *state);
 		if (ret)
 			BT_INSN(insn, "<=== (hint)");
 		return ret;
@@ -4166,6 +4281,7 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
 			   struct symbol *sym, struct insn_state *state)
 {
 	struct instruction *insn;
+	struct symbol *func;
 	int ret;
 
 	if (!sym->len) {
@@ -4183,9 +4299,18 @@ static int validate_symbol(struct objtool_file *file, struct section *sec,
 	if (opts.uaccess)
 		state->uaccess = sym->uaccess_safe;
 
-	ret = validate_branch(file, insn_func(insn), insn, *state);
+	func = insn_func(insn);
+
+	if (opts.checksum)
+		checksum_init(func);
+
+	ret = validate_branch(file, func, insn, *state);
 	if (ret)
 		BT_INSN(insn, "<=== (sym)");
+
+	if (opts.checksum)
+		checksum_finish(func);
+
 	return ret;
 }
 
@@ -4703,7 +4828,7 @@ int check(struct objtool_file *file)
 	if (opts.retpoline)
 		warnings += validate_retpoline(file);
 
-	if (opts.stackval || opts.orc || opts.uaccess) {
+	if (validate_branch_enabled()) {
 		int w = 0;
 
 		w += validate_functions(file);
@@ -4782,6 +4907,12 @@ int check(struct objtool_file *file)
 	if (opts.noabs)
 		warnings += check_abs_references(file);
 
+	if (opts.checksum) {
+		ret = create_sym_checksum_section(file);
+		if (ret)
+			goto out;
+	}
+
 	if (opts.orc && nr_insns) {
 		ret = orc_create(file);
 		if (ret)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 6095baba8e9c..0119b3b4c554 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -17,6 +17,7 @@
 #include <unistd.h>
 #include <errno.h>
 #include <libgen.h>
+#include <ctype.h>
 #include <linux/interval_tree_generic.h>
 #include <objtool/builtin.h>
 #include <objtool/elf.h>
@@ -412,7 +413,38 @@ static int read_sections(struct elf *elf)
 	return 0;
 }
 
-static void elf_add_symbol(struct elf *elf, struct symbol *sym)
+static const char *demangle_name(struct symbol *sym)
+{
+	char *str;
+
+	if (!is_local_sym(sym))
+		return sym->name;
+
+	if (!is_func_sym(sym) && !is_object_sym(sym))
+		return sym->name;
+
+	if (!strstarts(sym->name, "__UNIQUE_ID_") && !strchr(sym->name, '.'))
+		return sym->name;
+
+	str = strdup(sym->name);
+	if (!str) {
+		ERROR_GLIBC("strdup");
+		return NULL;
+	}
+
+	for (int i = strlen(str) - 1; i >= 0; i--) {
+		char c = str[i];
+
+		if (!isdigit(c) && c != '.') {
+			str[i + 1] = '\0';
+			break;
+		}
+	};
+
+	return str;
+}
+
+static int elf_add_symbol(struct elf *elf, struct symbol *sym)
 {
 	struct list_head *entry;
 	struct rb_node *pnode;
@@ -456,6 +488,12 @@ static void elf_add_symbol(struct elf *elf, struct symbol *sym)
 	if (is_func_sym(sym) && strstr(sym->name, ".cold"))
 		sym->cold = 1;
 	sym->pfunc = sym->cfunc = sym;
+
+	sym->demangled_name = demangle_name(sym);
+	if (!sym->demangled_name)
+		return -1;
+
+	return 0;
 }
 
 static int read_symbols(struct elf *elf)
@@ -529,7 +567,8 @@ static int read_symbols(struct elf *elf)
 		} else
 			sym->sec = find_section_by_index(elf, 0);
 
-		elf_add_symbol(elf, sym);
+		if (elf_add_symbol(elf, sym))
+			return -1;
 	}
 
 	if (opts.stats) {
@@ -867,7 +906,8 @@ non_local:
 		mark_sec_changed(elf, symtab_shndx, true);
 	}
 
-	elf_add_symbol(elf, sym);
+	if (elf_add_symbol(elf, sym))
+		return NULL;
 
 	return sym;
 }
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 7d559a2c13b7..338bdab6b9ad 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -9,12 +9,15 @@
 
 struct opts {
 	/* actions: */
+	bool cfi;
+	bool checksum;
 	bool dump_orc;
 	bool hack_jump_label;
 	bool hack_noinstr;
 	bool hack_skylake;
 	bool ibt;
 	bool mcount;
+	bool noabs;
 	bool noinstr;
 	bool orc;
 	bool retpoline;
@@ -25,8 +28,6 @@ struct opts {
 	bool static_call;
 	bool uaccess;
 	int prefix;
-	bool cfi;
-	bool noabs;
 
 	/* options: */
 	bool backtrace;
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 0f4e7ac929ef..d73b0c3ae1ee 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -65,8 +65,9 @@ struct instruction {
 	    unret		: 1,
 	    visited		: 4,
 	    no_reloc		: 1,
-	    hole		: 1;
-		/* 10 bit hole */
+	    hole		: 1,
+	    fake		: 1;
+		/* 9 bit hole */
 
 	struct alt_group *alt_group;
 	struct instruction *jump_dest;
diff --git a/tools/objtool/include/objtool/checksum.h b/tools/objtool/include/objtool/checksum.h
new file mode 100644
index 000000000000..927ca74b5c39
--- /dev/null
+++ b/tools/objtool/include/objtool/checksum.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _OBJTOOL_CHECKSUM_H
+#define _OBJTOOL_CHECKSUM_H
+
+#include <objtool/elf.h>
+
+#ifdef BUILD_KLP
+
+static inline void checksum_init(struct symbol *func)
+{
+	if (func && !func->csum.state) {
+		func->csum.state = XXH3_createState();
+		XXH3_64bits_reset(func->csum.state);
+	}
+}
+
+static inline void checksum_update(struct symbol *func,
+				   struct instruction *insn,
+				   const void *data, size_t size)
+{
+	XXH3_64bits_update(func->csum.state, data, size);
+}
+
+static inline void checksum_finish(struct symbol *func)
+{
+	if (func && func->csum.state) {
+		func->csum.checksum = XXH3_64bits_digest(func->csum.state);
+		func->csum.state = NULL;
+	}
+}
+
+#else /* !BUILD_KLP */
+
+static inline void checksum_init(struct symbol *func) {}
+static inline void checksum_update(struct symbol *func,
+				   struct instruction *insn,
+				   const void *data, size_t size) {}
+static inline void checksum_finish(struct symbol *func) {}
+
+#endif /* !BUILD_KLP */
+
+#endif /* _OBJTOOL_CHECKSUM_H */
diff --git a/tools/objtool/include/objtool/checksum_types.h b/tools/objtool/include/objtool/checksum_types.h
new file mode 100644
index 000000000000..507efdd8ab5b
--- /dev/null
+++ b/tools/objtool/include/objtool/checksum_types.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _OBJTOOL_CHECKSUM_TYPES_H
+#define _OBJTOOL_CHECKSUM_TYPES_H
+
+struct sym_checksum {
+	u64 addr;
+	u64 checksum;
+};
+
+#ifdef BUILD_KLP
+
+#include <xxhash.h>
+
+struct checksum {
+	XXH3_state_t *state;
+	XXH64_hash_t checksum;
+};
+
+#else /* !BUILD_KLP */
+
+struct checksum {};
+
+#endif /* !BUILD_KLP */
+
+#endif /* _OBJTOOL_CHECKSUM_TYPES_H */
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 814cfc0bbf16..bc7d8a6167f8 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -15,6 +15,7 @@
 #include <linux/jhash.h>
 
 #include <objtool/endianness.h>
+#include <objtool/checksum_types.h>
 #include <arch/elf.h>
 
 #define SYM_NAME_LEN		512
@@ -61,7 +62,7 @@ struct symbol {
 	struct elf_hash_node name_hash;
 	GElf_Sym sym;
 	struct section *sec;
-	const char *name;
+	const char *name, *demangled_name;
 	unsigned int idx, len;
 	unsigned long offset;
 	unsigned long __subtree_last;
@@ -84,6 +85,7 @@ struct symbol {
 	struct list_head pv_target;
 	struct reloc *relocs;
 	struct section *group_sec;
+	struct checksum csum;
 };
 
 struct reloc {
-- 
cgit v1.2.3


From a3493b33384a01a1f0e38b420d1a4766aec903a6 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:58 -0700
Subject: objtool/klp: Add --debug-checksum=<funcs> to show per-instruction
 checksums

Add a --debug-checksum=<funcs> option to the check subcommand to print
the calculated checksum of each instruction in the given functions.

This is useful for determining where two versions of a function begin to
diverge.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/builtin-check.c            |  6 +++++
 tools/objtool/check.c                    | 42 ++++++++++++++++++++++++++++++++
 tools/objtool/include/objtool/builtin.h  |  1 +
 tools/objtool/include/objtool/checksum.h |  1 +
 tools/objtool/include/objtool/elf.h      |  1 +
 tools/objtool/include/objtool/warn.h     | 19 +++++++++++++++
 6 files changed, 70 insertions(+)

(limited to 'tools/objtool')

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 14daa1357c8b..7b6fd60b022b 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -94,6 +94,7 @@ static const struct option check_options[] = {
 	OPT_GROUP("Options:"),
 	OPT_BOOLEAN(0,		 "backtrace", &opts.backtrace, "unwind on error"),
 	OPT_BOOLEAN(0,		 "backup", &opts.backup, "create backup (.orig) file on warning/error"),
+	OPT_STRING(0,		 "debug-checksum", &opts.debug_checksum,  "funcs", "enable checksum debug output"),
 	OPT_BOOLEAN(0,		 "dry-run", &opts.dryrun, "don't write modifications"),
 	OPT_BOOLEAN(0,		 "link", &opts.link, "object is a linked object"),
 	OPT_BOOLEAN(0,		 "module", &opts.module, "object is part of a kernel module"),
@@ -168,6 +169,11 @@ static bool opts_valid(void)
 	}
 #endif
 
+	if (opts.debug_checksum && !opts.checksum) {
+		ERROR("--debug-checksum requires --checksum");
+		return false;
+	}
+
 	if (opts.checksum		||
 	    opts.hack_jump_label	||
 	    opts.hack_noinstr		||
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index f5adbd23c42d..0f5278127f37 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3580,6 +3580,44 @@ static bool skip_alt_group(struct instruction *insn)
 	return alt_insn->type == INSN_CLAC || alt_insn->type == INSN_STAC;
 }
 
+static int checksum_debug_init(struct objtool_file *file)
+{
+	char *dup, *s;
+
+	if (!opts.debug_checksum)
+		return 0;
+
+	dup = strdup(opts.debug_checksum);
+	if (!dup) {
+		ERROR_GLIBC("strdup");
+		return -1;
+	}
+
+	s = dup;
+	while (*s) {
+		struct symbol *func;
+		char *comma;
+
+		comma = strchr(s, ',');
+		if (comma)
+			*comma = '\0';
+
+		func = find_symbol_by_name(file->elf, s);
+		if (!func || !is_func_sym(func))
+			WARN("--debug-checksum: can't find '%s'", s);
+		else
+			func->debug_checksum = 1;
+
+		if (!comma)
+			break;
+
+		s = comma + 1;
+	}
+
+	free(dup);
+	return 0;
+}
+
 static void checksum_update_insn(struct objtool_file *file, struct symbol *func,
 				 struct instruction *insn)
 {
@@ -4818,6 +4856,10 @@ int check(struct objtool_file *file)
 	cfi_hash_add(&init_cfi);
 	cfi_hash_add(&func_cfi);
 
+	ret = checksum_debug_init(file);
+	if (ret)
+		goto out;
+
 	ret = decode_sections(file);
 	if (ret)
 		goto out;
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 338bdab6b9ad..cee9fc031877 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -32,6 +32,7 @@ struct opts {
 	/* options: */
 	bool backtrace;
 	bool backup;
+	const char *debug_checksum;
 	bool dryrun;
 	bool link;
 	bool mnop;
diff --git a/tools/objtool/include/objtool/checksum.h b/tools/objtool/include/objtool/checksum.h
index 927ca74b5c39..7fe21608722a 100644
--- a/tools/objtool/include/objtool/checksum.h
+++ b/tools/objtool/include/objtool/checksum.h
@@ -19,6 +19,7 @@ static inline void checksum_update(struct symbol *func,
 				   const void *data, size_t size)
 {
 	XXH3_64bits_update(func->csum.state, data, size);
+	dbg_checksum(func, insn, XXH3_64bits_digest(func->csum.state));
 }
 
 static inline void checksum_finish(struct symbol *func)
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index bc7d8a6167f8..a1f1762f89c4 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -82,6 +82,7 @@ struct symbol {
 	u8 nocfi             : 1;
 	u8 cold		     : 1;
 	u8 prefix	     : 1;
+	u8 debug_checksum    : 1;
 	struct list_head pv_target;
 	struct reloc *relocs;
 	struct section *group_sec;
diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
index cb8fe846d9dd..29173a1368d7 100644
--- a/tools/objtool/include/objtool/warn.h
+++ b/tools/objtool/include/objtool/warn.h
@@ -102,4 +102,23 @@ static inline char *offstr(struct section *sec, unsigned long offset)
 #define ERROR_FUNC(sec, offset, format, ...) __WARN_FUNC(ERROR_STR, sec, offset, format, ##__VA_ARGS__)
 #define ERROR_INSN(insn, format, ...) WARN_FUNC(insn->sec, insn->offset, format, ##__VA_ARGS__)
 
+
+#define __dbg(format, ...)						\
+	fprintf(stderr,							\
+		"DEBUG: %s%s" format "\n",				\
+		objname ?: "",						\
+		objname ? ": " : "",					\
+		##__VA_ARGS__)
+
+#define dbg_checksum(func, insn, checksum)				\
+({									\
+	if (unlikely(insn->sym && insn->sym->pfunc &&			\
+		     insn->sym->pfunc->debug_checksum)) {		\
+		char *insn_off = offstr(insn->sec, insn->offset);	\
+		__dbg("checksum: %s %s %016lx",				\
+		      func->name, insn_off, checksum);			\
+		free(insn_off);						\
+	}								\
+})
+
 #endif /* _WARN_H */
-- 
cgit v1.2.3


From dd590d4d57ebeeb826823c288741f2ed20f452af Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:03:59 -0700
Subject: objtool/klp: Introduce klp diff subcommand for diffing object files

Add a new klp diff subcommand which performs a binary diff between two
object files and extracts changed functions into a new object which can
then be linked into a livepatch module.

This builds on concepts from the longstanding out-of-tree kpatch [1]
project which began in 2012 and has been used for many years to generate
livepatch modules for production kernels.  However, this is a complete
rewrite which incorporates hard-earned lessons from 12+ years of
maintaining kpatch.

Key improvements compared to kpatch-build:

  - Integrated with objtool: Leverages objtool's existing control-flow
    graph analysis to help detect changed functions.

  - Works on vmlinux.o: Supports late-linked objects, making it
    compatible with LTO, IBT, and similar.

  - Simplified code base: ~3k fewer lines of code.

  - Upstream: No more out-of-tree #ifdef hacks, far less cruft.

  - Cleaner internals: Vastly simplified logic for symbol/section/reloc
    inclusion and special section extraction.

  - Robust __LINE__ macro handling: Avoids false positive binary diffs
    caused by the __LINE__ macro by introducing a fix-patch-lines script
    (coming in a later patch) which injects #line directives into the
    source .patch to preserve the original line numbers at compile time.

Note the end result of this subcommand is not yet functionally complete.
Livepatch needs some ELF magic which linkers don't like:

  - Two relocation sections (.rela*, .klp.rela*) for the same text
    section.

  - Use of SHN_LIVEPATCH to mark livepatch symbols.

Unfortunately linkers tend to mangle such things.  To work around that,
klp diff generates a linker-compliant intermediate binary which encodes
the relevant KLP section/reloc/symbol metadata.

After module linking, a klp post-link step (coming soon) will clean up
the mess and convert the linked .ko into a fully compliant livepatch
module.

Note this subcommand requires the diffed binaries to have been compiled
with -ffunction-sections and -fdata-sections, and processed with
'objtool --checksum'.  Those constraints will be handled by a klp-build
script introduced in a later patch.

Without '-ffunction-sections -fdata-sections', reliable object diffing
would be infeasible due to toolchain limitations:

  - For intra-file+intra-section references, the compiler might
    occasionally generated hard-coded instruction offsets instead of
    relocations.

  - Section-symbol-based references can be ambiguous:

    - Overlapping or zero-length symbols create ambiguity as to which
      symbol is being referenced.

    - A reference to the end of a symbol (e.g., checking array bounds)
      can be misinterpreted as a reference to the next symbol, or vice
      versa.

A potential future alternative to '-ffunction-sections -fdata-sections'
would be to introduce a toolchain option that forces symbol-based
(non-section) relocations.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/Build                     |    4 +-
 tools/objtool/Makefile                  |    3 +-
 tools/objtool/arch/x86/decode.c         |   40 +
 tools/objtool/builtin-klp.c             |   52 +
 tools/objtool/check.c                   |   14 -
 tools/objtool/elf.c                     |   21 +-
 tools/objtool/include/objtool/arch.h    |    1 +
 tools/objtool/include/objtool/builtin.h |    2 +
 tools/objtool/include/objtool/elf.h     |   56 +-
 tools/objtool/include/objtool/klp.h     |   31 +
 tools/objtool/include/objtool/objtool.h |    2 +
 tools/objtool/include/objtool/util.h    |   19 +
 tools/objtool/klp-diff.c                | 1646 +++++++++++++++++++++++++++++++
 tools/objtool/objtool.c                 |   41 +-
 tools/objtool/sync-check.sh             |    1 +
 tools/objtool/weak.c                    |    7 +
 16 files changed, 1909 insertions(+), 31 deletions(-)
 create mode 100644 tools/objtool/builtin-klp.c
 create mode 100644 tools/objtool/include/objtool/klp.h
 create mode 100644 tools/objtool/include/objtool/util.h
 create mode 100644 tools/objtool/klp-diff.c

(limited to 'tools/objtool')

diff --git a/tools/objtool/Build b/tools/objtool/Build
index a3cdf8af6635..0b01657671d7 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -8,8 +8,8 @@ objtool-y += builtin-check.o
 objtool-y += elf.o
 objtool-y += objtool.o
 
-objtool-$(BUILD_ORC) += orc_gen.o
-objtool-$(BUILD_ORC) += orc_dump.o
+objtool-$(BUILD_ORC) += orc_gen.o orc_dump.o
+objtool-$(BUILD_KLP) += builtin-klp.o klp-diff.o
 
 objtool-y += libstring.o
 objtool-y += libctype.o
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 958761c05b7c..48928c9bebef 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -15,13 +15,14 @@ ifeq ($(ARCH_HAS_KLP),y)
 	HAVE_XXHASH = $(shell echo "int main() {}" | \
 		      $(HOSTCC) -xc - -o /dev/null -lxxhash 2> /dev/null && echo y || echo n)
 	ifeq ($(HAVE_XXHASH),y)
+		BUILD_KLP	 := y
 		LIBXXHASH_CFLAGS := $(shell $(HOSTPKG_CONFIG) libxxhash --cflags 2>/dev/null) \
 				    -DBUILD_KLP
 		LIBXXHASH_LIBS   := $(shell $(HOSTPKG_CONFIG) libxxhash --libs 2>/dev/null || echo -lxxhash)
 	endif
 endif
 
-export BUILD_ORC
+export BUILD_ORC BUILD_KLP
 
 ifeq ($(srctree),)
 srctree := $(patsubst %/,%,$(dir $(CURDIR)))
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index b2c320f701f9..5c72beeaa3a7 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -88,6 +88,46 @@ s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc)
 	return phys_to_virt(addend);
 }
 
+static void scan_for_insn(struct section *sec, unsigned long offset,
+			  unsigned long *insn_off, unsigned int *insn_len)
+{
+	unsigned long o = 0;
+	struct insn insn;
+
+	while (1) {
+
+		insn_decode(&insn, sec->data->d_buf + o, sec_size(sec) - o,
+			    INSN_MODE_64);
+
+		if (o + insn.length > offset) {
+			*insn_off = o;
+			*insn_len = insn.length;
+			return;
+		}
+
+		o += insn.length;
+	}
+}
+
+u64 arch_adjusted_addend(struct reloc *reloc)
+{
+	unsigned int type = reloc_type(reloc);
+	s64 addend = reloc_addend(reloc);
+	unsigned long insn_off;
+	unsigned int insn_len;
+
+	if (type == R_X86_64_PLT32)
+		return addend + 4;
+
+	if (type != R_X86_64_PC32 || !is_text_sec(reloc->sec->base))
+		return addend;
+
+	scan_for_insn(reloc->sec->base, reloc_offset(reloc),
+		      &insn_off, &insn_len);
+
+	return addend + insn_off + insn_len - reloc_offset(reloc);
+}
+
 unsigned long arch_jump_destination(struct instruction *insn)
 {
 	return insn->offset + insn->len + insn->immediate;
diff --git a/tools/objtool/builtin-klp.c b/tools/objtool/builtin-klp.c
new file mode 100644
index 000000000000..9b13dd1182af
--- /dev/null
+++ b/tools/objtool/builtin-klp.c
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <subcmd/parse-options.h>
+#include <string.h>
+#include <stdlib.h>
+#include <objtool/builtin.h>
+#include <objtool/objtool.h>
+#include <objtool/klp.h>
+
+struct subcmd {
+	const char *name;
+	const char *description;
+	int (*fn)(int, const char **);
+};
+
+static struct subcmd subcmds[] = {
+	{ "diff",		"Generate binary diff of two object files",		cmd_klp_diff, },
+};
+
+static void cmd_klp_usage(void)
+{
+	fprintf(stderr, "usage: objtool klp <subcommand> [<options>]\n\n");
+	fprintf(stderr, "Subcommands:\n");
+
+	for (int i = 0; i < ARRAY_SIZE(subcmds); i++) {
+		struct subcmd *cmd = &subcmds[i];
+
+		fprintf(stderr, "  %s\t%s\n", cmd->name, cmd->description);
+	}
+
+	exit(1);
+}
+
+int cmd_klp(int argc, const char **argv)
+{
+	argc--;
+	argv++;
+
+	if (!argc)
+		cmd_klp_usage();
+
+	if (argc) {
+		for (int i = 0; i < ARRAY_SIZE(subcmds); i++) {
+			struct subcmd *cmd = &subcmds[i];
+
+			if (!strcmp(cmd->name, argv[0]))
+				return cmd->fn(argc, argv);
+		}
+	}
+
+	cmd_klp_usage();
+	return 0;
+}
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0f5278127f37..8d17d930d0c8 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -185,20 +185,6 @@ static bool is_sibling_call(struct instruction *insn)
 	return (is_static_jump(insn) && insn_call_dest(insn));
 }
 
-/*
- * Checks if a string ends with another.
- */
-static bool str_ends_with(const char *s, const char *sub)
-{
-	const int slen = strlen(s);
-	const int sublen = strlen(sub);
-
-	if (sublen > slen)
-		return 0;
-
-	return !memcmp(s + slen - sublen, sub, sublen);
-}
-
 /*
  * Checks if a function is a Rust "noreturn" one.
  */
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 0119b3b4c554..e1daae0630be 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -288,6 +288,18 @@ struct symbol *find_symbol_by_name(const struct elf *elf, const char *name)
 	return NULL;
 }
 
+struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *name)
+{
+	struct symbol *sym;
+
+	elf_hash_for_each_possible(symbol_name, sym, name_hash, str_hash(name)) {
+		if (!strcmp(sym->name, name) && !is_local_sym(sym))
+			return sym;
+	}
+
+	return NULL;
+}
+
 struct reloc *find_reloc_by_dest_range(const struct elf *elf, struct section *sec,
 				     unsigned long offset, unsigned int len)
 {
@@ -475,6 +487,8 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym)
 	else
 		entry = &sym->sec->symbol_list;
 	list_add(&sym->list, entry);
+
+	list_add_tail(&sym->global_list, &elf->symbols);
 	elf_hash_add(symbol, &sym->hash, sym->idx);
 	elf_hash_add(symbol_name, &sym->name_hash, str_hash(sym->name));
 
@@ -531,6 +545,9 @@ static int read_symbols(struct elf *elf)
 		ERROR_GLIBC("calloc");
 		return -1;
 	}
+
+	INIT_LIST_HEAD(&elf->symbols);
+
 	for (i = 0; i < symbols_nr; i++) {
 		sym = &elf->symbol_data[i];
 
@@ -639,7 +656,7 @@ static int mark_group_syms(struct elf *elf)
 		return -1;
 	}
 
-	list_for_each_entry(sec, &elf->sections, list) {
+	for_each_sec(elf, sec) {
 		if (sec->sh.sh_type == SHT_GROUP &&
 		    sec->sh.sh_link == symtab->idx) {
 			sym = find_symbol_by_index(elf, sec->sh.sh_info);
@@ -1224,6 +1241,8 @@ struct elf *elf_create_file(GElf_Ehdr *ehdr, const char *name)
 		return NULL;
 	}
 
+	INIT_LIST_HEAD(&elf->symbols);
+
 	if (!elf_alloc_hash(section,		1000) ||
 	    !elf_alloc_hash(section_name,	1000) ||
 	    !elf_alloc_hash(symbol,		10000) ||
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index a4502947307a..d89f8b5ec14e 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -84,6 +84,7 @@ bool arch_callee_saved_reg(unsigned char reg);
 unsigned long arch_jump_destination(struct instruction *insn);
 
 s64 arch_insn_adjusted_addend(struct instruction *insn, struct reloc *reloc);
+u64 arch_adjusted_addend(struct reloc *reloc);
 
 const char *arch_nop_insn(int len);
 const char *arch_ret_insn(int len);
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index cee9fc031877..bb0b25eb08ba 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -53,4 +53,6 @@ int objtool_run(int argc, const char **argv);
 
 int make_backup(void);
 
+int cmd_klp(int argc, const char **argv);
+
 #endif /* _BUILTIN_H */
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index a1f1762f89c4..e2cd817fca52 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -18,6 +18,7 @@
 #include <objtool/checksum_types.h>
 #include <arch/elf.h>
 
+#define SEC_NAME_LEN		1024
 #define SYM_NAME_LEN		512
 
 #define bswap_if_needed(elf, val) __bswap_if_needed(&elf->ehdr, val)
@@ -53,10 +54,12 @@ struct section {
 	bool _changed, text, rodata, noinstr, init, truncate;
 	struct reloc *relocs;
 	unsigned long nr_alloc_relocs;
+	struct section *twin;
 };
 
 struct symbol {
 	struct list_head list;
+	struct list_head global_list;
 	struct rb_node node;
 	struct elf_hash_node hash;
 	struct elf_hash_node name_hash;
@@ -83,10 +86,13 @@ struct symbol {
 	u8 cold		     : 1;
 	u8 prefix	     : 1;
 	u8 debug_checksum    : 1;
+	u8 changed	     : 1;
+	u8 included	     : 1;
 	struct list_head pv_target;
 	struct reloc *relocs;
 	struct section *group_sec;
 	struct checksum csum;
+	struct symbol *twin, *clone;
 };
 
 struct reloc {
@@ -104,6 +110,7 @@ struct elf {
 	const char *name, *tmp_name;
 	unsigned int num_files;
 	struct list_head sections;
+	struct list_head symbols;
 	unsigned long num_relocs;
 
 	int symbol_bits;
@@ -179,6 +186,7 @@ struct section *find_section_by_name(const struct elf *elf, const char *name);
 struct symbol *find_func_by_offset(struct section *sec, unsigned long offset);
 struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset);
 struct symbol *find_symbol_by_name(const struct elf *elf, const char *name);
+struct symbol *find_global_symbol_by_name(const struct elf *elf, const char *name);
 struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset);
 int find_symbol_hole_containing(const struct section *sec, unsigned long offset);
 struct reloc *find_reloc_by_dest(const struct elf *elf, struct section *sec, unsigned long offset);
@@ -448,22 +456,48 @@ static inline void set_sym_next_reloc(struct reloc *reloc, struct reloc *next)
 #define sec_for_each_sym(sec, sym)					\
 	list_for_each_entry(sym, &sec->symbol_list, list)
 
+#define sec_prev_sym(sym)						\
+	sym->sec && sym->list.prev != &sym->sec->symbol_list ?		\
+	list_prev_entry(sym, list) : NULL
+
 #define for_each_sym(elf, sym)						\
-	for (struct section *__sec, *__fake = (struct section *)1;	\
-	     __fake; __fake = NULL)					\
-		for_each_sec(elf, __sec)				\
-			sec_for_each_sym(__sec, sym)
+	list_for_each_entry(sym, &elf->symbols, global_list)
+
+#define for_each_sym_continue(elf, sym)					\
+	list_for_each_entry_continue(sym, &elf->symbols, global_list)
+
+#define rsec_next_reloc(rsec, reloc)					\
+	reloc_idx(reloc) < sec_num_entries(rsec) - 1 ? reloc + 1 : NULL
 
 #define for_each_reloc(rsec, reloc)					\
-	for (int __i = 0, __fake = 1; __fake; __fake = 0)		\
-		for (reloc = rsec->relocs;				\
-		     __i < sec_num_entries(rsec);			\
-		     __i++, reloc++)
+	for (reloc = rsec->relocs; reloc; reloc = rsec_next_reloc(rsec, reloc))
 
 #define for_each_reloc_from(rsec, reloc)				\
-	for (int __i = reloc_idx(reloc);				\
-	     __i < sec_num_entries(rsec);				\
-	     __i++, reloc++)
+	for (; reloc; reloc = rsec_next_reloc(rsec, reloc))
+
+#define for_each_reloc_continue(rsec, reloc)				\
+	for (reloc = rsec_next_reloc(rsec, reloc); reloc;		\
+	     reloc = rsec_next_reloc(rsec, reloc))
+
+#define sym_for_each_reloc(elf, sym, reloc)				\
+	for (reloc = find_reloc_by_dest_range(elf, sym->sec,		\
+					      sym->offset, sym->len);	\
+	     reloc && reloc_offset(reloc) <  sym->offset + sym->len;	\
+	     reloc = rsec_next_reloc(sym->sec->rsec, reloc))
+
+static inline struct symbol *get_func_prefix(struct symbol *func)
+{
+	struct symbol *prev;
+
+	if (!is_func_sym(func))
+		return NULL;
+
+	prev = sec_prev_sym(func);
+	if (prev && is_prefix_func(prev))
+		return prev;
+
+	return NULL;
+}
 
 #define OFFSET_STRIDE_BITS	4
 #define OFFSET_STRIDE		(1UL << OFFSET_STRIDE_BITS)
diff --git a/tools/objtool/include/objtool/klp.h b/tools/objtool/include/objtool/klp.h
new file mode 100644
index 000000000000..07928fac059b
--- /dev/null
+++ b/tools/objtool/include/objtool/klp.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _OBJTOOL_KLP_H
+#define _OBJTOOL_KLP_H
+
+/*
+ * __klp_objects and __klp_funcs are created by klp diff and used by the patch
+ * module init code to build the klp_patch, klp_object and klp_func structs
+ * needed by the livepatch API.
+ */
+#define KLP_OBJECTS_SEC	"__klp_objects"
+#define KLP_FUNCS_SEC	"__klp_funcs"
+
+/*
+ * __klp_relocs is an intermediate section which are created by klp diff and
+ * converted into KLP symbols/relas by "objtool klp post-link".  This is needed
+ * to work around the linker, which doesn't preserve SHN_LIVEPATCH or
+ * SHF_RELA_LIVEPATCH, nor does it support having two RELA sections for a
+ * single PROGBITS section.
+ */
+#define KLP_RELOCS_SEC	"__klp_relocs"
+#define KLP_STRINGS_SEC	".rodata.klp.str1.1"
+
+struct klp_reloc {
+	void *offset;
+	void *sym;
+	u32 type;
+};
+
+int cmd_klp_diff(int argc, const char **argv);
+
+#endif /* _OBJTOOL_KLP_H */
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index c0dc86a78ff6..7f70b41d1b8d 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -39,6 +39,8 @@ struct objtool_file {
 	struct pv_state *pv_ops;
 };
 
+char *top_level_dir(const char *file);
+
 struct objtool_file *objtool_open_read(const char *_objname);
 
 int objtool_pv_add(struct objtool_file *file, int idx, struct symbol *func);
diff --git a/tools/objtool/include/objtool/util.h b/tools/objtool/include/objtool/util.h
new file mode 100644
index 000000000000..a0180b312f73
--- /dev/null
+++ b/tools/objtool/include/objtool/util.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _UTIL_H
+#define _UTIL_H
+
+#include <objtool/warn.h>
+
+#define snprintf_check(str, size, format, args...)			\
+({									\
+	int __ret = snprintf(str, size, format, args);			\
+	if (__ret < 0)							\
+		ERROR_GLIBC("snprintf");				\
+	else if (__ret >= size)						\
+		ERROR("snprintf() failed for '" format "'", args);	\
+	else								\
+		__ret = 0;						\
+	__ret;								\
+})
+
+#endif /* _UTIL_H */
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
new file mode 100644
index 000000000000..0d69b621a26c
--- /dev/null
+++ b/tools/objtool/klp-diff.c
@@ -0,0 +1,1646 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#define _GNU_SOURCE /* memmem() */
+#include <subcmd/parse-options.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libgen.h>
+#include <stdio.h>
+#include <ctype.h>
+
+#include <objtool/objtool.h>
+#include <objtool/warn.h>
+#include <objtool/arch.h>
+#include <objtool/klp.h>
+#include <objtool/util.h>
+#include <arch/special.h>
+
+#include <linux/objtool_types.h>
+#include <linux/livepatch_external.h>
+#include <linux/stringify.h>
+#include <linux/string.h>
+#include <linux/jhash.h>
+
+#define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
+
+struct elfs {
+	struct elf *orig, *patched, *out;
+	const char *modname;
+};
+
+struct export {
+	struct hlist_node hash;
+	char *mod, *sym;
+};
+
+static const char * const klp_diff_usage[] = {
+	"objtool klp diff [<options>] <in1.o> <in2.o> <out.o>",
+	NULL,
+};
+
+static const struct option klp_diff_options[] = {
+	OPT_END(),
+};
+
+static DEFINE_HASHTABLE(exports, 15);
+
+static inline u32 str_hash(const char *str)
+{
+	return jhash(str, strlen(str), 0);
+}
+
+static int read_exports(void)
+{
+	const char *symvers = "Module.symvers";
+	char line[1024], *path = NULL;
+	unsigned int line_num = 1;
+	FILE *file;
+
+	file = fopen(symvers, "r");
+	if (!file) {
+		path = top_level_dir(symvers);
+		if (!path) {
+			ERROR("can't open '%s', \"objtool diff\" should be run from the kernel tree", symvers);
+			return -1;
+		}
+
+		file = fopen(path, "r");
+		if (!file) {
+			ERROR_GLIBC("fopen");
+			return -1;
+		}
+	}
+
+	while (fgets(line, 1024, file)) {
+		char *sym, *mod, *type;
+		struct export *export;
+
+		sym = strchr(line, '\t');
+		if (!sym) {
+			ERROR("malformed Module.symvers (sym) at line %d", line_num);
+			return -1;
+		}
+
+		*sym++ = '\0';
+
+		mod = strchr(sym, '\t');
+		if (!mod) {
+			ERROR("malformed Module.symvers (mod) at line %d", line_num);
+			return -1;
+		}
+
+		*mod++ = '\0';
+
+		type = strchr(mod, '\t');
+		if (!type) {
+			ERROR("malformed Module.symvers (type) at line %d", line_num);
+			return -1;
+		}
+
+		*type++ = '\0';
+
+		if (*sym == '\0' || *mod == '\0') {
+			ERROR("malformed Module.symvers at line %d", line_num);
+			return -1;
+		}
+
+		export = calloc(1, sizeof(*export));
+		if (!export) {
+			ERROR_GLIBC("calloc");
+			return -1;
+		}
+
+		export->mod = strdup(mod);
+		if (!export->mod) {
+			ERROR_GLIBC("strdup");
+			return -1;
+		}
+
+		export->sym = strdup(sym);
+		if (!export->sym) {
+			ERROR_GLIBC("strdup");
+			return -1;
+		}
+
+		hash_add(exports, &export->hash, str_hash(sym));
+	}
+
+	free(path);
+	fclose(file);
+
+	return 0;
+}
+
+static int read_sym_checksums(struct elf *elf)
+{
+	struct section *sec;
+
+	sec = find_section_by_name(elf, ".discard.sym_checksum");
+	if (!sec) {
+		ERROR("'%s' missing .discard.sym_checksum section, file not processed by 'objtool --checksum'?",
+		      elf->name);
+		return -1;
+	}
+
+	if (!sec->rsec) {
+		ERROR("missing reloc section for .discard.sym_checksum");
+		return -1;
+	}
+
+	if (sec_size(sec) % sizeof(struct sym_checksum)) {
+		ERROR("struct sym_checksum size mismatch");
+		return -1;
+	}
+
+	for (int i = 0; i < sec_size(sec) / sizeof(struct sym_checksum); i++) {
+		struct sym_checksum *sym_checksum;
+		struct reloc *reloc;
+		struct symbol *sym;
+
+		sym_checksum = (struct sym_checksum *)sec->data->d_buf + i;
+
+		reloc = find_reloc_by_dest(elf, sec, i * sizeof(*sym_checksum));
+		if (!reloc) {
+			ERROR("can't find reloc for sym_checksum[%d]", i);
+			return -1;
+		}
+
+		sym = reloc->sym;
+
+		if (is_sec_sym(sym)) {
+			ERROR("not sure how to handle section %s", sym->name);
+			return -1;
+		}
+
+		if (is_func_sym(sym))
+			sym->csum.checksum = sym_checksum->checksum;
+	}
+
+	return 0;
+}
+
+static struct symbol *first_file_symbol(struct elf *elf)
+{
+	struct symbol *sym;
+
+	for_each_sym(elf, sym) {
+		if (is_file_sym(sym))
+			return sym;
+	}
+
+	return NULL;
+}
+
+static struct symbol *next_file_symbol(struct elf *elf, struct symbol *sym)
+{
+	for_each_sym_continue(elf, sym) {
+		if (is_file_sym(sym))
+			return sym;
+	}
+
+	return NULL;
+}
+
+/*
+ * Certain static local variables should never be correlated.  They will be
+ * used in place rather than referencing the originals.
+ */
+static bool is_uncorrelated_static_local(struct symbol *sym)
+{
+	static const char * const vars[] = {
+		"__key.",
+		"__warned.",
+		"__already_done.",
+		"__func__.",
+		"_rs.",
+		"descriptor.",
+		"CSWTCH.",
+	};
+
+	if (!is_object_sym(sym) || !is_local_sym(sym))
+		return false;
+
+	if (!strcmp(sym->sec->name, ".data.once"))
+		return true;
+
+	for (int i = 0; i < ARRAY_SIZE(vars); i++) {
+		if (strstarts(sym->name, vars[i]))
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * Clang emits several useless .Ltmp_* code labels.
+ */
+static bool is_clang_tmp_label(struct symbol *sym)
+{
+	return sym->type == STT_NOTYPE &&
+	       is_text_sec(sym->sec) &&
+	       strstarts(sym->name, ".Ltmp") &&
+	       isdigit(sym->name[5]);
+}
+
+static bool is_special_section(struct section *sec)
+{
+	static const char * const specials[] = {
+		".altinstructions",
+		".smp_locks",
+		"__bug_table",
+		"__ex_table",
+		"__jump_table",
+		"__mcount_loc",
+
+		/*
+		 * Extract .static_call_sites here to inherit non-module
+		 * preferential treatment.  The later static call processing
+		 * during klp module build will be skipped when it sees this
+		 * section already exists.
+		 */
+		".static_call_sites",
+	};
+
+	static const char * const non_special_discards[] = {
+		".discard.addressable",
+		".discard.sym_checksum",
+	};
+
+	if (is_text_sec(sec))
+		return false;
+
+	for (int i = 0; i < ARRAY_SIZE(specials); i++) {
+		if (!strcmp(sec->name, specials[i]))
+			return true;
+	}
+
+	/* Most .discard data sections are special */
+	for (int i = 0; i < ARRAY_SIZE(non_special_discards); i++) {
+		if (!strcmp(sec->name, non_special_discards[i]))
+			return false;
+	}
+
+	return strstarts(sec->name, ".discard.");
+}
+
+/*
+ * These sections are referenced by special sections but aren't considered
+ * special sections themselves.
+ */
+static bool is_special_section_aux(struct section *sec)
+{
+	static const char * const specials_aux[] = {
+		".altinstr_replacement",
+		".altinstr_aux",
+	};
+
+	for (int i = 0; i < ARRAY_SIZE(specials_aux); i++) {
+		if (!strcmp(sec->name, specials_aux[i]))
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * These symbols should never be correlated, so their local patched versions
+ * are used instead of linking to the originals.
+ */
+static bool dont_correlate(struct symbol *sym)
+{
+	return is_file_sym(sym) ||
+	       is_null_sym(sym) ||
+	       is_sec_sym(sym) ||
+	       is_prefix_func(sym) ||
+	       is_uncorrelated_static_local(sym) ||
+	       is_clang_tmp_label(sym) ||
+	       is_string_sec(sym->sec) ||
+	       is_special_section(sym->sec) ||
+	       is_special_section_aux(sym->sec) ||
+	       strstarts(sym->name, "__initcall__");
+}
+
+/*
+ * For each symbol in the original kernel, find its corresponding "twin" in the
+ * patched kernel.
+ */
+static int correlate_symbols(struct elfs *e)
+{
+	struct symbol *file1_sym, *file2_sym;
+	struct symbol *sym1, *sym2;
+
+	/* Correlate locals */
+	for (file1_sym = first_file_symbol(e->orig),
+	     file2_sym = first_file_symbol(e->patched); ;
+	     file1_sym = next_file_symbol(e->orig, file1_sym),
+	     file2_sym = next_file_symbol(e->patched, file2_sym)) {
+
+		if (!file1_sym && file2_sym) {
+			ERROR("FILE symbol mismatch: NULL != %s", file2_sym->name);
+			return -1;
+		}
+
+		if (file1_sym && !file2_sym) {
+			ERROR("FILE symbol mismatch: %s != NULL", file1_sym->name);
+			return -1;
+		}
+
+		if (!file1_sym)
+			break;
+
+		if (strcmp(file1_sym->name, file2_sym->name)) {
+			ERROR("FILE symbol mismatch: %s != %s", file1_sym->name, file2_sym->name);
+			return -1;
+		}
+
+		file1_sym->twin = file2_sym;
+		file2_sym->twin = file1_sym;
+
+		sym1 = file1_sym;
+
+		for_each_sym_continue(e->orig, sym1) {
+			if (is_file_sym(sym1) || !is_local_sym(sym1))
+				break;
+
+			if (dont_correlate(sym1))
+				continue;
+
+			sym2 = file2_sym;
+			for_each_sym_continue(e->patched, sym2) {
+				if (is_file_sym(sym2) || !is_local_sym(sym2))
+					break;
+
+				if (sym2->twin || dont_correlate(sym2))
+					continue;
+
+				if (strcmp(sym1->demangled_name, sym2->demangled_name))
+					continue;
+
+				sym1->twin = sym2;
+				sym2->twin = sym1;
+				break;
+			}
+		}
+	}
+
+	/* Correlate globals */
+	for_each_sym(e->orig, sym1) {
+		if (sym1->bind == STB_LOCAL)
+			continue;
+
+		sym2 = find_global_symbol_by_name(e->patched, sym1->name);
+
+		if (sym2 && !sym2->twin && !strcmp(sym1->name, sym2->name)) {
+			sym1->twin = sym2;
+			sym2->twin = sym1;
+		}
+	}
+
+	for_each_sym(e->orig, sym1) {
+		if (sym1->twin || dont_correlate(sym1))
+			continue;
+		WARN("no correlation: %s", sym1->name);
+	}
+
+	return 0;
+}
+
+/* "sympos" is used by livepatch to disambiguate duplicate symbol names */
+static unsigned long find_sympos(struct elf *elf, struct symbol *sym)
+{
+	bool vmlinux = str_ends_with(objname, "vmlinux.o");
+	unsigned long sympos = 0, nr_matches = 0;
+	bool has_dup = false;
+	struct symbol *s;
+
+	if (sym->bind != STB_LOCAL)
+		return 0;
+
+	if (vmlinux && sym->type == STT_FUNC) {
+		/*
+		 * HACK: Unfortunately, symbol ordering can differ between
+		 * vmlinux.o and vmlinux due to the linker script emitting
+		 * .text.unlikely* before .text*.  Count .text.unlikely* first.
+		 *
+		 * TODO: Disambiguate symbols more reliably (checksums?)
+		 */
+		for_each_sym(elf, s) {
+			if (strstarts(s->sec->name, ".text.unlikely") &&
+			    !strcmp(s->name, sym->name)) {
+				nr_matches++;
+				if (s == sym)
+					sympos = nr_matches;
+				else
+					has_dup = true;
+			}
+		}
+		for_each_sym(elf, s) {
+			if (!strstarts(s->sec->name, ".text.unlikely") &&
+			    !strcmp(s->name, sym->name)) {
+				nr_matches++;
+				if (s == sym)
+					sympos = nr_matches;
+				else
+					has_dup = true;
+			}
+		}
+	} else {
+		for_each_sym(elf, s) {
+			if (!strcmp(s->name, sym->name)) {
+				nr_matches++;
+				if (s == sym)
+					sympos = nr_matches;
+				else
+					has_dup = true;
+			}
+		}
+	}
+
+	if (!sympos) {
+		ERROR("can't find sympos for %s", sym->name);
+		return ULONG_MAX;
+	}
+
+	return has_dup ? sympos : 0;
+}
+
+static int clone_sym_relocs(struct elfs *e, struct symbol *patched_sym);
+
+static struct symbol *__clone_symbol(struct elf *elf, struct symbol *patched_sym,
+				     bool data_too)
+{
+	struct section *out_sec = NULL;
+	unsigned long offset = 0;
+	struct symbol *out_sym;
+
+	if (data_too && !is_undef_sym(patched_sym)) {
+		struct section *patched_sec = patched_sym->sec;
+
+		out_sec = find_section_by_name(elf, patched_sec->name);
+		if (!out_sec) {
+			out_sec = elf_create_section(elf, patched_sec->name, 0,
+						     patched_sec->sh.sh_entsize,
+						     patched_sec->sh.sh_type,
+						     patched_sec->sh.sh_addralign,
+						     patched_sec->sh.sh_flags);
+			if (!out_sec)
+				return NULL;
+		}
+
+		if (is_string_sec(patched_sym->sec)) {
+			out_sym = elf_create_section_symbol(elf, out_sec);
+			if (!out_sym)
+				return NULL;
+
+			goto sym_created;
+		}
+
+		if (!is_sec_sym(patched_sym))
+			offset = sec_size(out_sec);
+
+		if (patched_sym->len || is_sec_sym(patched_sym)) {
+			void *data = NULL;
+			size_t size;
+
+			/* bss doesn't have data */
+			if (patched_sym->sec->data->d_buf)
+				data = patched_sym->sec->data->d_buf + patched_sym->offset;
+
+			if (is_sec_sym(patched_sym))
+				size = sec_size(patched_sym->sec);
+			else
+				size = patched_sym->len;
+
+			if (!elf_add_data(elf, out_sec, data, size))
+				return NULL;
+		}
+	}
+
+	out_sym = elf_create_symbol(elf, patched_sym->name, out_sec,
+				    patched_sym->bind, patched_sym->type,
+				    offset, patched_sym->len);
+	if (!out_sym)
+		return NULL;
+
+sym_created:
+	patched_sym->clone = out_sym;
+	out_sym->clone = patched_sym;
+
+	return out_sym;
+}
+
+/*
+ * Copy a symbol to the output object, optionally including its data and
+ * relocations.
+ */
+static struct symbol *clone_symbol(struct elfs *e, struct symbol *patched_sym,
+				   bool data_too)
+{
+	struct symbol *pfx;
+
+	if (patched_sym->clone)
+		return patched_sym->clone;
+
+	/* Make sure the prefix gets cloned first */
+	if (is_func_sym(patched_sym) && data_too) {
+		pfx = get_func_prefix(patched_sym);
+		if (pfx)
+			clone_symbol(e, pfx, true);
+	}
+
+	if (!__clone_symbol(e->out, patched_sym, data_too))
+		return NULL;
+
+	if (data_too && clone_sym_relocs(e, patched_sym))
+		return NULL;
+
+	return patched_sym->clone;
+}
+
+static void mark_included_function(struct symbol *func)
+{
+	struct symbol *pfx;
+
+	func->included = 1;
+
+	/* Include prefix function */
+	pfx = get_func_prefix(func);
+	if (pfx)
+		pfx->included = 1;
+
+	/* Make sure .cold parent+child always stay together */
+	if (func->cfunc && func->cfunc != func)
+		func->cfunc->included = 1;
+	if (func->pfunc && func->pfunc != func)
+		func->pfunc->included = 1;
+}
+
+/*
+ * Copy all changed functions (and their dependencies) from the patched object
+ * to the output object.
+ */
+static int mark_changed_functions(struct elfs *e)
+{
+	struct symbol *sym_orig, *patched_sym;
+	bool changed = false;
+
+	/* Find changed functions */
+	for_each_sym(e->orig, sym_orig) {
+		if (!is_func_sym(sym_orig) || is_prefix_func(sym_orig))
+			continue;
+
+		patched_sym = sym_orig->twin;
+		if (!patched_sym)
+			continue;
+
+		if (sym_orig->csum.checksum != patched_sym->csum.checksum) {
+			patched_sym->changed = 1;
+			mark_included_function(patched_sym);
+			changed = true;
+		}
+	}
+
+	/* Find added functions and print them */
+	for_each_sym(e->patched, patched_sym) {
+		if (!is_func_sym(patched_sym) || is_prefix_func(patched_sym))
+			continue;
+
+		if (!patched_sym->twin) {
+			printf("%s: new function: %s\n", objname, patched_sym->name);
+			mark_included_function(patched_sym);
+			changed = true;
+		}
+	}
+
+	/* Print changed functions */
+	for_each_sym(e->patched, patched_sym) {
+		if (patched_sym->changed)
+			printf("%s: changed function: %s\n", objname, patched_sym->name);
+	}
+
+	return !changed ? -1 : 0;
+}
+
+static int clone_included_functions(struct elfs *e)
+{
+	struct symbol *patched_sym;
+
+	for_each_sym(e->patched, patched_sym) {
+		if (patched_sym->included) {
+			if (!clone_symbol(e, patched_sym, true))
+				return -1;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Determine whether a relocation should reference the section rather than the
+ * underlying symbol.
+ */
+static bool section_reference_needed(struct section *sec)
+{
+	/*
+	 * String symbols are zero-length and uncorrelated.  It's easier to
+	 * deal with them as section symbols.
+	 */
+	if (is_string_sec(sec))
+		return true;
+
+	/*
+	 * .rodata has mostly anonymous data so there's no way to determine the
+	 * length of a needed reference.  just copy the whole section if needed.
+	 */
+	if (strstarts(sec->name, ".rodata"))
+		return true;
+
+	/* UBSAN anonymous data */
+	if (strstarts(sec->name, ".data..Lubsan") ||	/* GCC */
+	    strstarts(sec->name, ".data..L__unnamed_"))	/* Clang */
+		return true;
+
+	return false;
+}
+
+static bool is_reloc_allowed(struct reloc *reloc)
+{
+	return section_reference_needed(reloc->sym->sec) == is_sec_sym(reloc->sym);
+}
+
+static struct export *find_export(struct symbol *sym)
+{
+	struct export *export;
+
+	hash_for_each_possible(exports, export, hash, str_hash(sym->name)) {
+		if (!strcmp(export->sym, sym->name))
+			return export;
+	}
+
+	return NULL;
+}
+
+static const char *__find_modname(struct elfs *e)
+{
+	struct section *sec;
+	char *name;
+
+	sec = find_section_by_name(e->orig, ".modinfo");
+	if (!sec) {
+		ERROR("missing .modinfo section");
+		return NULL;
+	}
+
+	name = memmem(sec->data->d_buf, sec_size(sec), "\0name=", 6);
+	if (name)
+		return name + 6;
+
+	name = strdup(e->orig->name);
+	if (!name) {
+		ERROR_GLIBC("strdup");
+		return NULL;
+	}
+
+	for (char *c = name; *c; c++) {
+		if (*c == '/')
+			name = c + 1;
+		else if (*c == '-')
+			*c = '_';
+		else if (*c == '.') {
+			*c = '\0';
+			break;
+		}
+	}
+
+	return name;
+}
+
+/* Get the object's module name as defined by the kernel (and klp_object) */
+static const char *find_modname(struct elfs *e)
+{
+	const char *modname;
+
+	if (e->modname)
+		return e->modname;
+
+	modname = __find_modname(e);
+	e->modname = modname;
+	return modname;
+}
+
+/*
+ * Copying a function from its native compiled environment to a kernel module
+ * removes its natural access to local functions/variables and unexported
+ * globals.  References to such symbols need to be converted to KLP relocs so
+ * the kernel arch relocation code knows to apply them and where to find the
+ * symbols.  Particularly, duplicate static symbols need to be disambiguated.
+ */
+static bool klp_reloc_needed(struct reloc *patched_reloc)
+{
+	struct symbol *patched_sym = patched_reloc->sym;
+	struct export *export;
+
+	/* no external symbol to reference */
+	if (dont_correlate(patched_sym))
+		return false;
+
+	/* For included functions, a regular reloc will do. */
+	if (patched_sym->included)
+		return false;
+
+	/*
+	 * If exported by a module, it has to be a klp reloc.  Thanks to the
+	 * clusterfunk that is late module patching, the patch module is
+	 * allowed to be loaded before any modules it depends on.
+	 *
+	 * If exported by vmlinux, a normal reloc will do.
+	 */
+	export = find_export(patched_sym);
+	if (export)
+		return strcmp(export->mod, "vmlinux");
+
+	if (!patched_sym->twin) {
+		/*
+		 * Presumably the symbol and its reference were added by the
+		 * patch.  The symbol could be defined in this .o or in another
+		 * .o in the patch module.
+		 *
+		 * This check needs to be *after* the export check due to the
+		 * possibility of the patch adding a new UNDEF reference to an
+		 * exported symbol.
+		 */
+		return false;
+	}
+
+	/* Unexported symbol which lives in the original vmlinux or module. */
+	return true;
+}
+
+static int convert_reloc_sym_to_secsym(struct elf *elf, struct reloc *reloc)
+{
+	struct symbol *sym = reloc->sym;
+	struct section *sec = sym->sec;
+
+	if (!sec->sym && !elf_create_section_symbol(elf, sec))
+		return -1;
+
+	reloc->sym = sec->sym;
+	set_reloc_sym(elf, reloc, sym->idx);
+	set_reloc_addend(elf, reloc, sym->offset + reloc_addend(reloc));
+	return 0;
+}
+
+static int convert_reloc_secsym_to_sym(struct elf *elf, struct reloc *reloc)
+{
+	struct symbol *sym = reloc->sym;
+	struct section *sec = sym->sec;
+
+	/* If the symbol has a dedicated section, it's easy to find */
+	sym = find_symbol_by_offset(sec, 0);
+	if (sym && sym->len == sec_size(sec))
+		goto found_sym;
+
+	/* No dedicated section; find the symbol manually */
+	sym = find_symbol_containing(sec, arch_adjusted_addend(reloc));
+	if (!sym) {
+		/*
+		 * This can happen for special section references to weak code
+		 * whose symbol has been stripped by the linker.
+		 */
+		return -1;
+	}
+
+found_sym:
+	reloc->sym = sym;
+	set_reloc_sym(elf, reloc, sym->idx);
+	set_reloc_addend(elf, reloc, reloc_addend(reloc) - sym->offset);
+	return 0;
+}
+
+/*
+ * Convert a relocation symbol reference to the needed format: either a section
+ * symbol or the underlying symbol itself.
+ */
+static int convert_reloc_sym(struct elf *elf, struct reloc *reloc)
+{
+	if (is_reloc_allowed(reloc))
+		return 0;
+
+	if (section_reference_needed(reloc->sym->sec))
+		return convert_reloc_sym_to_secsym(elf, reloc);
+	else
+		return convert_reloc_secsym_to_sym(elf, reloc);
+}
+
+/*
+ * Convert a regular relocation to a klp relocation (sort of).
+ */
+static int clone_reloc_klp(struct elfs *e, struct reloc *patched_reloc,
+			   struct section *sec, unsigned long offset,
+			   struct export *export)
+{
+	struct symbol *patched_sym = patched_reloc->sym;
+	s64 addend = reloc_addend(patched_reloc);
+	const char *sym_modname, *sym_orig_name;
+	static struct section *klp_relocs;
+	struct symbol *sym, *klp_sym;
+	unsigned long klp_reloc_off;
+	char sym_name[SYM_NAME_LEN];
+	struct klp_reloc klp_reloc;
+	unsigned long sympos;
+
+	if (!patched_sym->twin) {
+		ERROR("unexpected klp reloc for new symbol %s", patched_sym->name);
+		return -1;
+	}
+
+	/*
+	 * Keep the original reloc intact for now to avoid breaking objtool run
+	 * which relies on proper relocations for many of its features.  This
+	 * will be disabled later by "objtool klp post-link".
+	 *
+	 * Convert it to UNDEF (and WEAK to avoid modpost warnings).
+	 */
+
+	sym = patched_sym->clone;
+	if (!sym) {
+		/* STB_WEAK: avoid modpost undefined symbol warnings */
+		sym = elf_create_symbol(e->out, patched_sym->name, NULL,
+					STB_WEAK, patched_sym->type, 0, 0);
+		if (!sym)
+			return -1;
+
+		patched_sym->clone = sym;
+		sym->clone = patched_sym;
+	}
+
+	if (!elf_create_reloc(e->out, sec, offset, sym, addend, reloc_type(patched_reloc)))
+		return -1;
+
+	/*
+	 * Create the KLP symbol.
+	 */
+
+	if (export) {
+		sym_modname = export->mod;
+		sym_orig_name = export->sym;
+		sympos = 0;
+	} else {
+		sym_modname = find_modname(e);
+		if (!sym_modname)
+			return -1;
+
+		sym_orig_name = patched_sym->twin->name;
+		sympos = find_sympos(e->orig, patched_sym->twin);
+		if (sympos == ULONG_MAX)
+			return -1;
+	}
+
+	/* symbol format: .klp.sym.modname.sym_name,sympos */
+	if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_SYM_PREFIX "%s.%s,%ld",
+		      sym_modname, sym_orig_name, sympos))
+		return -1;
+
+	klp_sym = find_symbol_by_name(e->out, sym_name);
+	if (!klp_sym) {
+		/* STB_WEAK: avoid modpost undefined symbol warnings */
+		klp_sym = elf_create_symbol(e->out, sym_name, NULL,
+					    STB_WEAK, patched_sym->type, 0, 0);
+		if (!klp_sym)
+			return -1;
+	}
+
+	/*
+	 * Create the __klp_relocs entry.  This will be converted to an actual
+	 * KLP rela by "objtool klp post-link".
+	 *
+	 * This intermediate step is necessary to prevent corruption by the
+	 * linker, which doesn't know how to properly handle two rela sections
+	 * applying to the same base section.
+	 */
+
+	if (!klp_relocs) {
+		klp_relocs = elf_create_section(e->out, KLP_RELOCS_SEC, 0,
+						0, SHT_PROGBITS, 8, SHF_ALLOC);
+		if (!klp_relocs)
+			return -1;
+	}
+
+	klp_reloc_off = sec_size(klp_relocs);
+	memset(&klp_reloc, 0, sizeof(klp_reloc));
+
+	klp_reloc.type = reloc_type(patched_reloc);
+	if (!elf_add_data(e->out, klp_relocs, &klp_reloc, sizeof(klp_reloc)))
+		return -1;
+
+	/* klp_reloc.offset */
+	if (!sec->sym && !elf_create_section_symbol(e->out, sec))
+		return -1;
+
+	if (!elf_create_reloc(e->out, klp_relocs,
+			      klp_reloc_off + offsetof(struct klp_reloc, offset),
+			      sec->sym, offset, R_ABS64))
+		return -1;
+
+	/* klp_reloc.sym */
+	if (!elf_create_reloc(e->out, klp_relocs,
+			      klp_reloc_off + offsetof(struct klp_reloc, sym),
+			      klp_sym, addend, R_ABS64))
+		return -1;
+
+	return 0;
+}
+
+/* Copy a reloc and its symbol to the output object */
+static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
+			struct section *sec, unsigned long offset)
+{
+	struct symbol *patched_sym = patched_reloc->sym;
+	struct export *export = find_export(patched_sym);
+	long addend = reloc_addend(patched_reloc);
+	struct symbol *out_sym;
+	bool klp;
+
+	if (!is_reloc_allowed(patched_reloc)) {
+		ERROR_FUNC(patched_reloc->sec->base, reloc_offset(patched_reloc),
+			   "missing symbol for reference to %s+%ld",
+			   patched_sym->name, addend);
+		return -1;
+	}
+
+	klp = klp_reloc_needed(patched_reloc);
+
+	if (klp) {
+		if (clone_reloc_klp(e, patched_reloc, sec, offset, export))
+			return -1;
+
+		return 0;
+	}
+
+	/*
+	 * Why !export sets 'data_too':
+	 *
+	 * Unexported non-klp symbols need to live in the patch module,
+	 * otherwise there will be unresolved symbols.  Notably, this includes:
+	 *
+	 *   - New functions/data
+	 *   - String sections
+	 *   - Special section entries
+	 *   - Uncorrelated static local variables
+	 *   - UBSAN sections
+	 */
+	out_sym = clone_symbol(e, patched_sym, patched_sym->included || !export);
+	if (!out_sym)
+		return -1;
+
+	/*
+	 * For strings, all references use section symbols, thanks to
+	 * section_reference_needed().  clone_symbol() has cloned an empty
+	 * version of the string section.  Now copy the string itself.
+	 */
+	if (is_string_sec(patched_sym->sec)) {
+		const char *str = patched_sym->sec->data->d_buf + addend;
+
+		addend = elf_add_string(e->out, out_sym->sec, str);
+		if (addend == -1)
+			return -1;
+	}
+
+	if (!elf_create_reloc(e->out, sec, offset, out_sym, addend,
+			      reloc_type(patched_reloc)))
+		return -1;
+
+	return 0;
+}
+
+/* Copy all relocs needed for a symbol's contents */
+static int clone_sym_relocs(struct elfs *e, struct symbol *patched_sym)
+{
+	struct section *patched_rsec = patched_sym->sec->rsec;
+	struct reloc *patched_reloc;
+	unsigned long start, end;
+	struct symbol *out_sym;
+
+	out_sym = patched_sym->clone;
+	if (!out_sym) {
+		ERROR("no clone for %s", patched_sym->name);
+		return -1;
+	}
+
+	if (!patched_rsec)
+		return 0;
+
+	if (!is_sec_sym(patched_sym) && !patched_sym->len)
+		return 0;
+
+	if (is_string_sec(patched_sym->sec))
+		return 0;
+
+	if (is_sec_sym(patched_sym)) {
+		start = 0;
+		end = sec_size(patched_sym->sec);
+	} else {
+		start = patched_sym->offset;
+		end = start + patched_sym->len;
+	}
+
+	for_each_reloc(patched_rsec, patched_reloc) {
+		unsigned long offset;
+
+		if (reloc_offset(patched_reloc) < start ||
+		    reloc_offset(patched_reloc) >= end)
+			continue;
+
+		/*
+		 * Skip any reloc referencing .altinstr_aux.  Its code is
+		 * always patched by alternatives.  See ALTERNATIVE_TERNARY().
+		 */
+		if (patched_reloc->sym->sec &&
+		    !strcmp(patched_reloc->sym->sec->name, ".altinstr_aux"))
+			continue;
+
+		if (convert_reloc_sym(e->patched, patched_reloc)) {
+			ERROR_FUNC(patched_rsec->base, reloc_offset(patched_reloc),
+				   "failed to convert reloc sym '%s' to its proper format",
+				   patched_reloc->sym->name);
+			return -1;
+		}
+
+		offset = out_sym->offset + (reloc_offset(patched_reloc) - patched_sym->offset);
+
+		if (clone_reloc(e, patched_reloc, out_sym->sec, offset))
+			return -1;
+	}
+	return 0;
+
+}
+
+static int create_fake_symbol(struct elf *elf, struct section *sec,
+			      unsigned long offset, size_t size)
+{
+	char name[SYM_NAME_LEN];
+	unsigned int type;
+	static int ctr;
+	char *c;
+
+	if (snprintf_check(name, SYM_NAME_LEN, "%s_%d", sec->name, ctr++))
+		return -1;
+
+	for (c = name; *c; c++)
+		if (*c == '.')
+			*c = '_';
+
+	/*
+	 * STT_NOTYPE: Prevent objtool from validating .altinstr_replacement
+	 *	       while still allowing objdump to disassemble it.
+	 */
+	type = is_text_sec(sec) ? STT_NOTYPE : STT_OBJECT;
+	return elf_create_symbol(elf, name, sec, STB_LOCAL, type, offset, size) ? 0 : -1;
+}
+
+/*
+ * Special sections (alternatives, etc) are basically arrays of structs.
+ * For all the special sections, create a symbol for each struct entry.  This
+ * is a bit cumbersome, but it makes the extracting of the individual entries
+ * much more straightforward.
+ *
+ * There are three ways to identify the entry sizes for a special section:
+ *
+ * 1) ELF section header sh_entsize: Ideally this would be used almost
+ *    everywhere.  But unfortunately the toolchains make it difficult.  The
+ *    assembler .[push]section directive syntax only takes entsize when
+ *    combined with SHF_MERGE.  But Clang disallows combining SHF_MERGE with
+ *    SHF_WRITE.  And some special sections do need to be writable.
+ *
+ *    Another place this wouldn't work is .altinstr_replacement, whose entries
+ *    don't have a fixed size.
+ *
+ * 2) ANNOTATE_DATA_SPECIAL: This is a lightweight objtool annotation which
+ *    points to the beginning of each entry.  The size of the entry is then
+ *    inferred by the location of the subsequent annotation (or end of
+ *    section).
+ *
+ * 3) Simple array of pointers: If the special section is just a basic array of
+ *    pointers, the entry size can be inferred by the number of relocations.
+ *    No annotations needed.
+ *
+ * Note I also tried to create per-entry symbols at the time of creation, in
+ * the original [inline] asm.  Unfortunately, creating uniquely named symbols
+ * is trickier than one might think, especially with Clang inline asm.  I
+ * eventually just gave up trying to make that work, in favor of using
+ * ANNOTATE_DATA_SPECIAL and creating the symbols here after the fact.
+ */
+static int create_fake_symbols(struct elf *elf)
+{
+	struct section *sec;
+	struct reloc *reloc;
+
+	/*
+	 * 1) Make symbols for all the ANNOTATE_DATA_SPECIAL entries:
+	 */
+
+	sec = find_section_by_name(elf, ".discard.annotate_data");
+	if (!sec || !sec->rsec)
+		return 0;
+
+	for_each_reloc(sec->rsec, reloc) {
+		unsigned long offset, size;
+		struct reloc *next_reloc;
+
+		if (annotype(elf, sec, reloc) != ANNOTYPE_DATA_SPECIAL)
+			continue;
+
+		offset = reloc_addend(reloc);
+
+		size = 0;
+		next_reloc = reloc;
+		for_each_reloc_continue(sec->rsec, next_reloc) {
+			if (annotype(elf, sec, next_reloc) != ANNOTYPE_DATA_SPECIAL ||
+			    next_reloc->sym->sec != reloc->sym->sec)
+				continue;
+
+			size = reloc_addend(next_reloc) - offset;
+			break;
+		}
+
+		if (!size)
+			size = sec_size(reloc->sym->sec) - offset;
+
+		if (create_fake_symbol(elf, reloc->sym->sec, offset, size))
+			return -1;
+	}
+
+	/*
+	 * 2) Make symbols for sh_entsize, and simple arrays of pointers:
+	 */
+
+	for_each_sec(elf, sec) {
+		unsigned int entry_size;
+		unsigned long offset;
+
+		if (!is_special_section(sec) || find_symbol_by_offset(sec, 0))
+			continue;
+
+		if (!sec->rsec) {
+			ERROR("%s: missing special section relocations", sec->name);
+			return -1;
+		}
+
+		entry_size = sec->sh.sh_entsize;
+		if (!entry_size) {
+			entry_size = arch_reloc_size(sec->rsec->relocs);
+			if (sec_size(sec) != entry_size * sec_num_entries(sec->rsec)) {
+				ERROR("%s: missing special section entsize or annotations", sec->name);
+				return -1;
+			}
+		}
+
+		for (offset = 0; offset < sec_size(sec); offset += entry_size) {
+			if (create_fake_symbol(elf, sec, offset, entry_size))
+				return -1;
+		}
+	}
+
+	return 0;
+}
+
+/* Keep a special section entry if it references an included function */
+static bool should_keep_special_sym(struct elf *elf, struct symbol *sym)
+{
+	struct reloc *reloc;
+
+	if (is_sec_sym(sym) || !sym->sec->rsec)
+		return false;
+
+	sym_for_each_reloc(elf, sym, reloc) {
+		if (convert_reloc_sym(elf, reloc))
+			continue;
+
+		if (is_func_sym(reloc->sym) && reloc->sym->included)
+			return true;
+	}
+
+	return false;
+}
+
+/*
+ * Klp relocations aren't allowed for __jump_table and .static_call_sites if
+ * the referenced symbol lives in a kernel module, because such klp relocs may
+ * be applied after static branch/call init, resulting in code corruption.
+ *
+ * Validate a special section entry to avoid that.  Note that an inert
+ * tracepoint is harmless enough, in that case just skip the entry and print a
+ * warning.  Otherwise, return an error.
+ *
+ * This is only a temporary limitation which will be fixed when livepatch adds
+ * support for submodules: fully self-contained modules which are embedded in
+ * the top-level livepatch module's data and which can be loaded on demand when
+ * their corresponding to-be-patched module gets loaded.  Then klp relocs can
+ * be retired.
+ *
+ * Return:
+ *   -1: error: validation failed
+ *    1: warning: tracepoint skipped
+ *    0: success
+ */
+static int validate_special_section_klp_reloc(struct elfs *e, struct symbol *sym)
+{
+	bool static_branch = !strcmp(sym->sec->name, "__jump_table");
+	bool static_call   = !strcmp(sym->sec->name, ".static_call_sites");
+	struct symbol *code_sym = NULL;
+	unsigned long code_offset = 0;
+	struct reloc *reloc;
+	int ret = 0;
+
+	if (!static_branch && !static_call)
+		return 0;
+
+	sym_for_each_reloc(e->patched, sym, reloc) {
+		const char *sym_modname;
+		struct export *export;
+
+		/* Static branch/call keys are always STT_OBJECT */
+		if (reloc->sym->type != STT_OBJECT) {
+
+			/* Save code location which can be printed below */
+			if (reloc->sym->type == STT_FUNC && !code_sym) {
+				code_sym = reloc->sym;
+				code_offset = reloc_addend(reloc);
+			}
+
+			continue;
+		}
+
+		if (!klp_reloc_needed(reloc))
+			continue;
+
+		export = find_export(reloc->sym);
+		if (export) {
+			sym_modname = export->mod;
+		} else {
+			sym_modname = find_modname(e);
+			if (!sym_modname)
+				return -1;
+		}
+
+		/* vmlinux keys are ok */
+		if (!strcmp(sym_modname, "vmlinux"))
+			continue;
+
+		if (static_branch) {
+			if (strstarts(reloc->sym->name, "__tracepoint_")) {
+				WARN("%s: disabling unsupported tracepoint %s",
+				     code_sym->name, reloc->sym->name + 13);
+				ret = 1;
+				continue;
+			}
+
+			ERROR("%s+0x%lx: unsupported static branch key %s.  Use static_key_enabled() instead",
+			      code_sym->name, code_offset, reloc->sym->name);
+			return -1;
+		}
+
+		/* static call */
+		if (strstarts(reloc->sym->name, "__SCK__tp_func_")) {
+			ret = 1;
+			continue;
+		}
+
+		ERROR("%s()+0x%lx: unsupported static call key %s.  Use KLP_STATIC_CALL() instead",
+		      code_sym->name, code_offset, reloc->sym->name);
+		return -1;
+	}
+
+	return ret;
+}
+
+static int clone_special_section(struct elfs *e, struct section *patched_sec)
+{
+	struct symbol *patched_sym;
+
+	/*
+	 * Extract all special section symbols (and their dependencies) which
+	 * reference included functions.
+	 */
+	sec_for_each_sym(patched_sec, patched_sym) {
+		int ret;
+
+		if (!is_object_sym(patched_sym))
+			continue;
+
+		if (!should_keep_special_sym(e->patched, patched_sym))
+			continue;
+
+		ret = validate_special_section_klp_reloc(e, patched_sym);
+		if (ret < 0)
+			return -1;
+		if (ret > 0)
+			continue;
+
+		if (!clone_symbol(e, patched_sym, true))
+			return -1;
+	}
+
+	return 0;
+}
+
+/* Extract only the needed bits from special sections */
+static int clone_special_sections(struct elfs *e)
+{
+	struct section *patched_sec;
+
+	if (create_fake_symbols(e->patched))
+		return -1;
+
+	for_each_sec(e->patched, patched_sec) {
+		if (is_special_section(patched_sec)) {
+			if (clone_special_section(e, patched_sec))
+				return -1;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Create __klp_objects and __klp_funcs sections which are intermediate
+ * sections provided as input to the patch module's init code for building the
+ * klp_patch, klp_object and klp_func structs for the livepatch API.
+ */
+static int create_klp_sections(struct elfs *e)
+{
+	size_t obj_size  = sizeof(struct klp_object_ext);
+	size_t func_size = sizeof(struct klp_func_ext);
+	struct section *obj_sec, *funcs_sec, *str_sec;
+	struct symbol *funcs_sym, *str_sym, *sym;
+	char sym_name[SYM_NAME_LEN];
+	unsigned int nr_funcs = 0;
+	const char *modname;
+	void *obj_data;
+	s64 addend;
+
+	obj_sec  = elf_create_section_pair(e->out, KLP_OBJECTS_SEC, obj_size, 0, 0);
+	if (!obj_sec)
+		return -1;
+
+	funcs_sec = elf_create_section_pair(e->out, KLP_FUNCS_SEC, func_size, 0, 0);
+	if (!funcs_sec)
+		return -1;
+
+	funcs_sym = elf_create_section_symbol(e->out, funcs_sec);
+	if (!funcs_sym)
+		return -1;
+
+	str_sec = elf_create_section(e->out, KLP_STRINGS_SEC, 0, 0,
+				     SHT_PROGBITS, 1,
+				     SHF_ALLOC | SHF_STRINGS | SHF_MERGE);
+	if (!str_sec)
+		return -1;
+
+	if (elf_add_string(e->out, str_sec, "") == -1)
+		return -1;
+
+	str_sym = elf_create_section_symbol(e->out, str_sec);
+	if (!str_sym)
+		return -1;
+
+	/* allocate klp_object_ext */
+	obj_data = elf_add_data(e->out, obj_sec, NULL, obj_size);
+	if (!obj_data)
+		return -1;
+
+	modname = find_modname(e);
+	if (!modname)
+		return -1;
+
+	/* klp_object_ext.name */
+	if (strcmp(modname, "vmlinux")) {
+		addend = elf_add_string(e->out, str_sec, modname);
+		if (addend == -1)
+			return -1;
+
+		if (!elf_create_reloc(e->out, obj_sec,
+				      offsetof(struct klp_object_ext, name),
+				      str_sym, addend, R_ABS64))
+			return -1;
+	}
+
+	/* klp_object_ext.funcs */
+	if (!elf_create_reloc(e->out, obj_sec, offsetof(struct klp_object_ext, funcs),
+			      funcs_sym, 0, R_ABS64))
+		return -1;
+
+	for_each_sym(e->out, sym) {
+		unsigned long offset = nr_funcs * func_size;
+		unsigned long sympos;
+		void *func_data;
+
+		if (!is_func_sym(sym) || sym->cold || !sym->clone || !sym->clone->changed)
+			continue;
+
+		/* allocate klp_func_ext */
+		func_data = elf_add_data(e->out, funcs_sec, NULL, func_size);
+		if (!func_data)
+			return -1;
+
+		/* klp_func_ext.old_name */
+		addend = elf_add_string(e->out, str_sec, sym->clone->twin->name);
+		if (addend == -1)
+			return -1;
+
+		if (!elf_create_reloc(e->out, funcs_sec,
+				      offset + offsetof(struct klp_func_ext, old_name),
+				      str_sym, addend, R_ABS64))
+			return -1;
+
+		/* klp_func_ext.new_func */
+		if (!elf_create_reloc(e->out, funcs_sec,
+				      offset + offsetof(struct klp_func_ext, new_func),
+				      sym, 0, R_ABS64))
+			return -1;
+
+		/* klp_func_ext.sympos */
+		BUILD_BUG_ON(sizeof(sympos) != sizeof_field(struct klp_func_ext, sympos));
+		sympos = find_sympos(e->orig, sym->clone->twin);
+		if (sympos == ULONG_MAX)
+			return -1;
+		memcpy(func_data + offsetof(struct klp_func_ext, sympos), &sympos,
+		       sizeof_field(struct klp_func_ext, sympos));
+
+		nr_funcs++;
+	}
+
+	/* klp_object_ext.nr_funcs */
+	BUILD_BUG_ON(sizeof(nr_funcs) != sizeof_field(struct klp_object_ext, nr_funcs));
+	memcpy(obj_data + offsetof(struct klp_object_ext, nr_funcs), &nr_funcs,
+	       sizeof_field(struct klp_object_ext, nr_funcs));
+
+	/*
+	 * Find callback pointers created by KLP_PRE_PATCH_CALLBACK() and
+	 * friends, and add them to the klp object.
+	 */
+
+	if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_PRE_PATCH_PREFIX "%s", modname))
+		return -1;
+
+	sym = find_symbol_by_name(e->out, sym_name);
+	if (sym) {
+		struct reloc *reloc;
+
+		reloc = find_reloc_by_dest(e->out, sym->sec, sym->offset);
+
+		if (!elf_create_reloc(e->out, obj_sec,
+				      offsetof(struct klp_object_ext, callbacks) +
+				      offsetof(struct klp_callbacks, pre_patch),
+				      reloc->sym, reloc_addend(reloc), R_ABS64))
+			return -1;
+	}
+
+	if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_POST_PATCH_PREFIX "%s", modname))
+		return -1;
+
+	sym = find_symbol_by_name(e->out, sym_name);
+	if (sym) {
+		struct reloc *reloc;
+
+		reloc = find_reloc_by_dest(e->out, sym->sec, sym->offset);
+
+		if (!elf_create_reloc(e->out, obj_sec,
+				      offsetof(struct klp_object_ext, callbacks) +
+				      offsetof(struct klp_callbacks, post_patch),
+				      reloc->sym, reloc_addend(reloc), R_ABS64))
+			return -1;
+	}
+
+	if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_PRE_UNPATCH_PREFIX "%s", modname))
+		return -1;
+
+	sym = find_symbol_by_name(e->out, sym_name);
+	if (sym) {
+		struct reloc *reloc;
+
+		reloc = find_reloc_by_dest(e->out, sym->sec, sym->offset);
+
+		if (!elf_create_reloc(e->out, obj_sec,
+				      offsetof(struct klp_object_ext, callbacks) +
+				      offsetof(struct klp_callbacks, pre_unpatch),
+				      reloc->sym, reloc_addend(reloc), R_ABS64))
+			return -1;
+	}
+
+	if (snprintf_check(sym_name, SYM_NAME_LEN, KLP_POST_UNPATCH_PREFIX "%s", modname))
+		return -1;
+
+	sym = find_symbol_by_name(e->out, sym_name);
+	if (sym) {
+		struct reloc *reloc;
+
+		reloc = find_reloc_by_dest(e->out, sym->sec, sym->offset);
+
+		if (!elf_create_reloc(e->out, obj_sec,
+				      offsetof(struct klp_object_ext, callbacks) +
+				      offsetof(struct klp_callbacks, post_unpatch),
+				      reloc->sym, reloc_addend(reloc), R_ABS64))
+			return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Copy all .modinfo import_ns= tags to ensure all namespaced exported symbols
+ * can be accessed via normal relocs.
+ */
+static int copy_import_ns(struct elfs *e)
+{
+	struct section *patched_sec, *out_sec = NULL;
+	char *import_ns, *data_end;
+
+	patched_sec = find_section_by_name(e->patched, ".modinfo");
+	if (!patched_sec)
+		return 0;
+
+	import_ns = patched_sec->data->d_buf;
+	if (!import_ns)
+		return 0;
+
+	for (data_end = import_ns + sec_size(patched_sec);
+	     import_ns < data_end;
+	     import_ns += strlen(import_ns) + 1) {
+
+		import_ns = memmem(import_ns, data_end - import_ns, "import_ns=", 10);
+		if (!import_ns)
+			return 0;
+
+		if (!out_sec) {
+			out_sec = find_section_by_name(e->out, ".modinfo");
+			if (!out_sec) {
+				out_sec = elf_create_section(e->out, ".modinfo", 0,
+							     patched_sec->sh.sh_entsize,
+							     patched_sec->sh.sh_type,
+							     patched_sec->sh.sh_addralign,
+							     patched_sec->sh.sh_flags);
+				if (!out_sec)
+					return -1;
+			}
+		}
+
+		if (!elf_add_data(e->out, out_sec, import_ns, strlen(import_ns) + 1))
+			return -1;
+	}
+
+	return 0;
+}
+
+int cmd_klp_diff(int argc, const char **argv)
+{
+	struct elfs e = {0};
+
+	argc = parse_options(argc, argv, klp_diff_options, klp_diff_usage, 0);
+	if (argc != 3)
+		usage_with_options(klp_diff_usage, klp_diff_options);
+
+	objname = argv[0];
+
+	e.orig = elf_open_read(argv[0], O_RDONLY);
+	e.patched = elf_open_read(argv[1], O_RDONLY);
+	e.out = NULL;
+
+	if (!e.orig || !e.patched)
+		return -1;
+
+	if (read_exports())
+		return -1;
+
+	if (read_sym_checksums(e.orig))
+		return -1;
+
+	if (read_sym_checksums(e.patched))
+		return -1;
+
+	if (correlate_symbols(&e))
+		return -1;
+
+	if (mark_changed_functions(&e))
+		return 0;
+
+	e.out = elf_create_file(&e.orig->ehdr, argv[2]);
+	if (!e.out)
+		return -1;
+
+	if (clone_included_functions(&e))
+		return -1;
+
+	if (clone_special_sections(&e))
+		return -1;
+
+	if (create_klp_sections(&e))
+		return -1;
+
+	if (copy_import_ns(&e))
+		return -1;
+
+	if  (elf_write(e.out))
+		return -1;
+
+	return elf_close(e.out);
+}
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index 5c8b974ad0f9..c8f611c1320d 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -16,8 +16,6 @@
 #include <objtool/objtool.h>
 #include <objtool/warn.h>
 
-bool help;
-
 static struct objtool_file file;
 
 struct objtool_file *objtool_open_read(const char *filename)
@@ -71,6 +69,39 @@ int objtool_pv_add(struct objtool_file *f, int idx, struct symbol *func)
 	return 0;
 }
 
+char *top_level_dir(const char *file)
+{
+	ssize_t len, self_len, file_len;
+	char self[PATH_MAX], *str;
+	int i;
+
+	len = readlink("/proc/self/exe", self, sizeof(self) - 1);
+	if (len <= 0)
+		return NULL;
+	self[len] = '\0';
+
+	for (i = 0; i < 3; i++) {
+		char *s = strrchr(self, '/');
+		if (!s)
+			return NULL;
+		*s = '\0';
+	}
+
+	self_len = strlen(self);
+	file_len = strlen(file);
+
+	str = malloc(self_len + file_len + 2);
+	if (!str)
+		return NULL;
+
+	memcpy(str, self, self_len);
+	str[self_len] = '/';
+	strcpy(str + self_len + 1, file);
+
+	return str;
+}
+
+
 int main(int argc, const char **argv)
 {
 	static const char *UNUSED = "OBJTOOL_NOT_IMPLEMENTED";
@@ -79,5 +110,11 @@ int main(int argc, const char **argv)
 	exec_cmd_init("objtool", UNUSED, UNUSED, UNUSED);
 	pager_init(UNUSED);
 
+	if (argc > 1 && !strcmp(argv[1], "klp")) {
+		argc--;
+		argv++;
+		return cmd_klp(argc, argv);
+	}
+
 	return objtool_run(argc, argv);
 }
diff --git a/tools/objtool/sync-check.sh b/tools/objtool/sync-check.sh
index 86d64e3ac6f7..e38167ca56a9 100755
--- a/tools/objtool/sync-check.sh
+++ b/tools/objtool/sync-check.sh
@@ -17,6 +17,7 @@ arch/x86/include/asm/emulate_prefix.h
 arch/x86/lib/x86-opcode-map.txt
 arch/x86/tools/gen-insn-attr-x86.awk
 include/linux/interval_tree_generic.h
+include/linux/livepatch_external.h
 include/linux/static_call_types.h
 "
 
diff --git a/tools/objtool/weak.c b/tools/objtool/weak.c
index d83f607733b0..d6562f292259 100644
--- a/tools/objtool/weak.c
+++ b/tools/objtool/weak.c
@@ -8,6 +8,8 @@
 #include <stdbool.h>
 #include <errno.h>
 #include <objtool/objtool.h>
+#include <objtool/arch.h>
+#include <objtool/builtin.h>
 
 #define UNSUPPORTED(name)						\
 ({									\
@@ -24,3 +26,8 @@ int __weak orc_create(struct objtool_file *file)
 {
 	UNSUPPORTED("ORC");
 }
+
+int __weak cmd_klp(int argc, const char **argv)
+{
+	UNSUPPORTED("klp");
+}
-- 
cgit v1.2.3


From 7c2575a6406fb85946b05d8dcc856686d3156354 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:04:00 -0700
Subject: objtool/klp: Add --debug option to show cloning decisions

Add a --debug option to klp diff which prints cloning decisions and an
indented dependency tree for all cloned symbols and relocations.  This
helps visualize which symbols and relocations were included and why.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/include/objtool/warn.h | 21 ++++++++++
 tools/objtool/klp-diff.c             | 75 ++++++++++++++++++++++++++++++++++++
 tools/objtool/objtool.c              |  3 ++
 3 files changed, 99 insertions(+)

(limited to 'tools/objtool')

diff --git a/tools/objtool/include/objtool/warn.h b/tools/objtool/include/objtool/warn.h
index 29173a1368d7..e88322d97573 100644
--- a/tools/objtool/include/objtool/warn.h
+++ b/tools/objtool/include/objtool/warn.h
@@ -102,6 +102,10 @@ static inline char *offstr(struct section *sec, unsigned long offset)
 #define ERROR_FUNC(sec, offset, format, ...) __WARN_FUNC(ERROR_STR, sec, offset, format, ##__VA_ARGS__)
 #define ERROR_INSN(insn, format, ...) WARN_FUNC(insn->sec, insn->offset, format, ##__VA_ARGS__)
 
+extern bool debug;
+extern int indent;
+
+static inline void unindent(int *unused) { indent--; }
 
 #define __dbg(format, ...)						\
 	fprintf(stderr,							\
@@ -110,6 +114,23 @@ static inline char *offstr(struct section *sec, unsigned long offset)
 		objname ? ": " : "",					\
 		##__VA_ARGS__)
 
+#define dbg(args...)							\
+({									\
+	if (unlikely(debug))						\
+		__dbg(args);						\
+})
+
+#define __dbg_indent(format, ...)					\
+({									\
+	if (unlikely(debug))						\
+		__dbg("%*s" format, indent * 8, "", ##__VA_ARGS__);	\
+})
+
+#define dbg_indent(args...)						\
+	int __attribute__((cleanup(unindent))) __dummy_##__COUNTER__;	\
+	__dbg_indent(args);						\
+	indent++
+
 #define dbg_checksum(func, insn, checksum)				\
 ({									\
 	if (unlikely(insn->sym && insn->sym->pfunc &&			\
diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index 0d69b621a26c..817d44394a78 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -38,6 +38,8 @@ static const char * const klp_diff_usage[] = {
 };
 
 static const struct option klp_diff_options[] = {
+	OPT_GROUP("Options:"),
+	OPT_BOOLEAN('d', "debug", &debug, "enable debug output"),
 	OPT_END(),
 };
 
@@ -48,6 +50,38 @@ static inline u32 str_hash(const char *str)
 	return jhash(str, strlen(str), 0);
 }
 
+static char *escape_str(const char *orig)
+{
+	size_t len = 0;
+	const char *a;
+	char *b, *new;
+
+	for (a = orig; *a; a++) {
+		switch (*a) {
+		case '\001': len += 5; break;
+		case '\n':
+		case '\t':   len += 2; break;
+		default: len++;
+		}
+	}
+
+	new = malloc(len + 1);
+	if (!new)
+		return NULL;
+
+	for (a = orig, b = new; *a; a++) {
+		switch (*a) {
+		case '\001': memcpy(b, "<SOH>", 5); b += 5; break;
+		case '\n': *b++ = '\\'; *b++ = 'n'; break;
+		case '\t': *b++ = '\\'; *b++ = 't'; break;
+		default:   *b++ = *a;
+		}
+	}
+
+	*b = '\0';
+	return new;
+}
+
 static int read_exports(void)
 {
 	const char *symvers = "Module.symvers";
@@ -528,6 +562,28 @@ sym_created:
 	return out_sym;
 }
 
+static const char *sym_type(struct symbol *sym)
+{
+	switch (sym->type) {
+	case STT_NOTYPE:  return "NOTYPE";
+	case STT_OBJECT:  return "OBJECT";
+	case STT_FUNC:    return "FUNC";
+	case STT_SECTION: return "SECTION";
+	case STT_FILE:    return "FILE";
+	default:	  return "UNKNOWN";
+	}
+}
+
+static const char *sym_bind(struct symbol *sym)
+{
+	switch (sym->bind) {
+	case STB_LOCAL:   return "LOCAL";
+	case STB_GLOBAL:  return "GLOBAL";
+	case STB_WEAK:    return "WEAK";
+	default:	  return "UNKNOWN";
+	}
+}
+
 /*
  * Copy a symbol to the output object, optionally including its data and
  * relocations.
@@ -540,6 +596,8 @@ static struct symbol *clone_symbol(struct elfs *e, struct symbol *patched_sym,
 	if (patched_sym->clone)
 		return patched_sym->clone;
 
+	dbg_indent("%s%s", patched_sym->name, data_too ? " [+DATA]" : "");
+
 	/* Make sure the prefix gets cloned first */
 	if (is_func_sym(patched_sym) && data_too) {
 		pfx = get_func_prefix(patched_sym);
@@ -902,6 +960,8 @@ static int clone_reloc_klp(struct elfs *e, struct reloc *patched_reloc,
 
 	klp_sym = find_symbol_by_name(e->out, sym_name);
 	if (!klp_sym) {
+		__dbg_indent("%s", sym_name);
+
 		/* STB_WEAK: avoid modpost undefined symbol warnings */
 		klp_sym = elf_create_symbol(e->out, sym_name, NULL,
 					    STB_WEAK, patched_sym->type, 0, 0);
@@ -950,6 +1010,17 @@ static int clone_reloc_klp(struct elfs *e, struct reloc *patched_reloc,
 	return 0;
 }
 
+#define dbg_clone_reloc(sec, offset, patched_sym, addend, export, klp)			\
+	dbg_indent("%s+0x%lx: %s%s0x%lx [%s%s%s%s%s%s]",				\
+		   sec->name, offset, patched_sym->name,				\
+		   addend >= 0 ? "+" : "-", labs(addend),				\
+		   sym_type(patched_sym),						\
+		   patched_sym->type == STT_SECTION ? "" : " ",				\
+		   patched_sym->type == STT_SECTION ? "" : sym_bind(patched_sym),	\
+		   is_undef_sym(patched_sym) ? " UNDEF" : "",				\
+		   export ? " EXPORTED" : "",						\
+		   klp ? " KLP" : "")
+
 /* Copy a reloc and its symbol to the output object */
 static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
 			struct section *sec, unsigned long offset)
@@ -969,6 +1040,8 @@ static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
 
 	klp = klp_reloc_needed(patched_reloc);
 
+	dbg_clone_reloc(sec, offset, patched_sym, addend, export, klp);
+
 	if (klp) {
 		if (clone_reloc_klp(e, patched_reloc, sec, offset, export))
 			return -1;
@@ -1000,6 +1073,8 @@ static int clone_reloc(struct elfs *e, struct reloc *patched_reloc,
 	if (is_string_sec(patched_sym->sec)) {
 		const char *str = patched_sym->sec->data->d_buf + addend;
 
+		__dbg_indent("\"%s\"", escape_str(str));
+
 		addend = elf_add_string(e->out, out_sym->sec, str);
 		if (addend == -1)
 			return -1;
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index c8f611c1320d..3c26ed561c7e 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -16,6 +16,9 @@
 #include <objtool/objtool.h>
 #include <objtool/warn.h>
 
+bool debug;
+int indent;
+
 static struct objtool_file file;
 
 struct objtool_file *objtool_open_read(const char *filename)
-- 
cgit v1.2.3


From ebe864b55304f74c4e1a8b6c899e34446b2be424 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:04:01 -0700
Subject: objtool/klp: Add post-link subcommand to finalize livepatch modules

Livepatch needs some ELF magic which linkers don't like:

  - Two relocation sections (.rela*, .klp.rela*) for the same text
    section.

  - Use of SHN_LIVEPATCH to mark livepatch symbols.

Unfortunately linkers tend to mangle such things.  To work around that,
klp diff generates a linker-compliant intermediate binary which encodes
the relevant KLP section/reloc/symbol metadata.

After module linking, the .ko then needs to be converted to an actual
livepatch module.  Introduce a new klp post-link subcommand to do so.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/Build                 |   2 +-
 tools/objtool/builtin-klp.c         |   1 +
 tools/objtool/include/objtool/klp.h |   4 +
 tools/objtool/klp-post-link.c       | 168 ++++++++++++++++++++++++++++++++++++
 4 files changed, 174 insertions(+), 1 deletion(-)
 create mode 100644 tools/objtool/klp-post-link.c

(limited to 'tools/objtool')

diff --git a/tools/objtool/Build b/tools/objtool/Build
index 0b01657671d7..8cd71b9a5eef 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -9,7 +9,7 @@ objtool-y += elf.o
 objtool-y += objtool.o
 
 objtool-$(BUILD_ORC) += orc_gen.o orc_dump.o
-objtool-$(BUILD_KLP) += builtin-klp.o klp-diff.o
+objtool-$(BUILD_KLP) += builtin-klp.o klp-diff.o klp-post-link.o
 
 objtool-y += libstring.o
 objtool-y += libctype.o
diff --git a/tools/objtool/builtin-klp.c b/tools/objtool/builtin-klp.c
index 9b13dd1182af..56d5a5b92f72 100644
--- a/tools/objtool/builtin-klp.c
+++ b/tools/objtool/builtin-klp.c
@@ -14,6 +14,7 @@ struct subcmd {
 
 static struct subcmd subcmds[] = {
 	{ "diff",		"Generate binary diff of two object files",		cmd_klp_diff, },
+	{ "post-link",		"Finalize klp symbols/relocs after module linking",	cmd_klp_post_link, },
 };
 
 static void cmd_klp_usage(void)
diff --git a/tools/objtool/include/objtool/klp.h b/tools/objtool/include/objtool/klp.h
index 07928fac059b..ad830a7ce55b 100644
--- a/tools/objtool/include/objtool/klp.h
+++ b/tools/objtool/include/objtool/klp.h
@@ -2,6 +2,9 @@
 #ifndef _OBJTOOL_KLP_H
 #define _OBJTOOL_KLP_H
 
+#define SHF_RELA_LIVEPATCH	0x00100000
+#define SHN_LIVEPATCH		0xff20
+
 /*
  * __klp_objects and __klp_funcs are created by klp diff and used by the patch
  * module init code to build the klp_patch, klp_object and klp_func structs
@@ -27,5 +30,6 @@ struct klp_reloc {
 };
 
 int cmd_klp_diff(int argc, const char **argv);
+int cmd_klp_post_link(int argc, const char **argv);
 
 #endif /* _OBJTOOL_KLP_H */
diff --git a/tools/objtool/klp-post-link.c b/tools/objtool/klp-post-link.c
new file mode 100644
index 000000000000..c013e39957b1
--- /dev/null
+++ b/tools/objtool/klp-post-link.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Read the intermediate KLP reloc/symbol representations created by klp diff
+ * and convert them to the proper format required by livepatch.  This needs to
+ * run last to avoid linker wreckage.  Linkers don't tend to handle the "two
+ * rela sections for a single base section" case very well, nor do they like
+ * SHN_LIVEPATCH.
+ *
+ * This is the final tool in the livepatch module generation pipeline:
+ *
+ *   kernel builds -> objtool klp diff -> module link -> objtool klp post-link
+ */
+
+#include <fcntl.h>
+#include <gelf.h>
+#include <objtool/objtool.h>
+#include <objtool/warn.h>
+#include <objtool/klp.h>
+#include <objtool/util.h>
+#include <linux/livepatch_external.h>
+
+static int fix_klp_relocs(struct elf *elf)
+{
+	struct section *symtab, *klp_relocs;
+
+	klp_relocs = find_section_by_name(elf, KLP_RELOCS_SEC);
+	if (!klp_relocs)
+		return 0;
+
+	symtab = find_section_by_name(elf, ".symtab");
+	if (!symtab) {
+		ERROR("missing .symtab");
+		return -1;
+	}
+
+	for (int i = 0; i < sec_size(klp_relocs) / sizeof(struct klp_reloc); i++) {
+		struct klp_reloc *klp_reloc;
+		unsigned long klp_reloc_off;
+		struct section *sec, *tmp, *klp_rsec;
+		unsigned long offset;
+		struct reloc *reloc;
+		char sym_modname[64];
+		char rsec_name[SEC_NAME_LEN];
+		u64 addend;
+		struct symbol *sym, *klp_sym;
+
+		klp_reloc_off = i * sizeof(*klp_reloc);
+		klp_reloc = klp_relocs->data->d_buf + klp_reloc_off;
+
+		/*
+		 * Read __klp_relocs[i]:
+		 */
+
+		/* klp_reloc.sec_offset */
+		reloc = find_reloc_by_dest(elf, klp_relocs,
+					   klp_reloc_off + offsetof(struct klp_reloc, offset));
+		if (!reloc) {
+			ERROR("malformed " KLP_RELOCS_SEC " section");
+			return -1;
+		}
+
+		sec = reloc->sym->sec;
+		offset = reloc_addend(reloc);
+
+		/* klp_reloc.sym */
+		reloc = find_reloc_by_dest(elf, klp_relocs,
+					   klp_reloc_off + offsetof(struct klp_reloc, sym));
+		if (!reloc) {
+			ERROR("malformed " KLP_RELOCS_SEC " section");
+			return -1;
+		}
+
+		klp_sym = reloc->sym;
+		addend = reloc_addend(reloc);
+
+		/* symbol format: .klp.sym.modname.sym_name,sympos */
+		if (sscanf(klp_sym->name + strlen(KLP_SYM_PREFIX), "%55[^.]", sym_modname) != 1)
+			ERROR("can't find modname in klp symbol '%s'", klp_sym->name);
+
+		/*
+		 * Create the KLP rela:
+		 */
+
+		/* section format: .klp.rela.sec_objname.section_name */
+		if (snprintf_check(rsec_name, SEC_NAME_LEN,
+				   KLP_RELOC_SEC_PREFIX "%s.%s",
+				   sym_modname, sec->name))
+			return -1;
+
+		klp_rsec = find_section_by_name(elf, rsec_name);
+		if (!klp_rsec) {
+			klp_rsec = elf_create_section(elf, rsec_name, 0,
+						      elf_rela_size(elf),
+						      SHT_RELA, elf_addr_size(elf),
+						      SHF_ALLOC | SHF_INFO_LINK | SHF_RELA_LIVEPATCH);
+			if (!klp_rsec)
+				return -1;
+
+			klp_rsec->sh.sh_link = symtab->idx;
+			klp_rsec->sh.sh_info = sec->idx;
+			klp_rsec->base = sec;
+		}
+
+		tmp = sec->rsec;
+		sec->rsec = klp_rsec;
+		if (!elf_create_reloc(elf, sec, offset, klp_sym, addend, klp_reloc->type))
+			return -1;
+		sec->rsec = tmp;
+
+		/*
+		 * Fix up the corresponding KLP symbol:
+		 */
+
+		klp_sym->sym.st_shndx = SHN_LIVEPATCH;
+		if (!gelf_update_sym(symtab->data, klp_sym->idx, &klp_sym->sym)) {
+			ERROR_ELF("gelf_update_sym");
+			return -1;
+		}
+
+		/*
+		 * Disable the original non-KLP reloc by converting it to R_*_NONE:
+		 */
+
+		reloc = find_reloc_by_dest(elf, sec, offset);
+		sym = reloc->sym;
+		sym->sym.st_shndx = SHN_LIVEPATCH;
+		set_reloc_type(elf, reloc, 0);
+		if (!gelf_update_sym(symtab->data, sym->idx, &sym->sym)) {
+			ERROR_ELF("gelf_update_sym");
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * This runs on the livepatch module after all other linking has been done.  It
+ * converts the intermediate __klp_relocs section into proper KLP relocs to be
+ * processed by livepatch.  This needs to run last to avoid linker wreckage.
+ * Linkers don't tend to handle the "two rela sections for a single base
+ * section" case very well, nor do they appreciate SHN_LIVEPATCH.
+ */
+int cmd_klp_post_link(int argc, const char **argv)
+{
+	struct elf *elf;
+
+	argc--;
+	argv++;
+
+	if (argc != 1) {
+		fprintf(stderr, "%d\n", argc);
+		fprintf(stderr, "usage: objtool link <file.ko>\n");
+		return -1;
+	}
+
+	elf = elf_open_read(argv[0], O_RDWR);
+	if (!elf)
+		return -1;
+
+	if (fix_klp_relocs(elf))
+		return -1;
+
+	if (elf_write(elf))
+		return -1;
+
+	return elf_close(elf);
+}
-- 
cgit v1.2.3


From 2058f6d1660edc4a9bda9bee627792b352121b10 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:04:02 -0700
Subject: objtool: Refactor prefix symbol creation code

The prefix symbol creation code currently ignores all errors, presumably
because some functions don't have the leading NOPs.

Shuffle the code around a bit, improve the error handling and document
why some errors are ignored.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c               | 57 +++++++++++++++++++++++++++++--------
 tools/objtool/elf.c                 | 17 -----------
 tools/objtool/include/objtool/elf.h |  2 --
 3 files changed, 45 insertions(+), 31 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8d17d930d0c8..b2659fbf7bc9 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -15,6 +15,7 @@
 #include <objtool/special.h>
 #include <objtool/warn.h>
 #include <objtool/checksum.h>
+#include <objtool/util.h>
 
 #include <linux/objtool_types.h>
 #include <linux/hashtable.h>
@@ -4233,14 +4234,43 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
 	return false;
 }
 
-static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
+/*
+ * For FineIBT or kCFI, a certain number of bytes preceding the function may be
+ * NOPs.  Those NOPs may be rewritten at runtime and executed, so give them a
+ * proper function name: __pfx_<func>.
+ *
+ * The NOPs may not exist for the following cases:
+ *
+ *   - compiler cloned functions (*.cold, *.part0, etc)
+ *   - asm functions created with inline asm or without SYM_FUNC_START()
+ *
+ * So return 0 if the NOPs are missing or the function already has a prefix
+ * symbol.
+ */
+static int create_prefix_symbol(struct objtool_file *file, struct symbol *func)
 {
 	struct instruction *insn, *prev;
+	char name[SYM_NAME_LEN];
 	struct cfi_state *cfi;
 
+	if (!is_func_sym(func) || is_prefix_func(func) ||
+	    func->cold || func->static_call_tramp)
+		return 0;
+
+	if ((strlen(func->name) + sizeof("__pfx_") > SYM_NAME_LEN)) {
+		WARN("%s: symbol name too long, can't create __pfx_ symbol",
+		      func->name);
+		return 0;
+	}
+
+	if (snprintf_check(name, SYM_NAME_LEN, "__pfx_%s", func->name))
+		return -1;
+
 	insn = find_insn(file, func->sec, func->offset);
-	if (!insn)
+	if (!insn) {
+		WARN("%s: can't find starting instruction", func->name);
 		return -1;
+	}
 
 	for (prev = prev_insn_same_sec(file, insn);
 	     prev;
@@ -4248,22 +4278,27 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
 		u64 offset;
 
 		if (prev->type != INSN_NOP)
-			return -1;
+			return 0;
 
 		offset = func->offset - prev->offset;
 
 		if (offset > opts.prefix)
-			return -1;
+			return 0;
 
 		if (offset < opts.prefix)
 			continue;
 
-		elf_create_prefix_symbol(file->elf, func, opts.prefix);
+		if (!elf_create_symbol(file->elf, name, func->sec,
+				       GELF_ST_BIND(func->sym.st_info),
+				       GELF_ST_TYPE(func->sym.st_info),
+				       prev->offset, opts.prefix))
+			return -1;
+
 		break;
 	}
 
 	if (!prev)
-		return -1;
+		return 0;
 
 	if (!insn->cfi) {
 		/*
@@ -4281,7 +4316,7 @@ static int add_prefix_symbol(struct objtool_file *file, struct symbol *func)
 	return 0;
 }
 
-static int add_prefix_symbols(struct objtool_file *file)
+static int create_prefix_symbols(struct objtool_file *file)
 {
 	struct section *sec;
 	struct symbol *func;
@@ -4291,10 +4326,8 @@ static int add_prefix_symbols(struct objtool_file *file)
 			continue;
 
 		sec_for_each_sym(sec, func) {
-			if (!is_func_sym(func))
-				continue;
-
-			add_prefix_symbol(file, func);
+			if (create_prefix_symbol(file, func))
+				return -1;
 		}
 	}
 
@@ -4921,7 +4954,7 @@ int check(struct objtool_file *file)
 	}
 
 	if (opts.prefix) {
-		ret = add_prefix_symbols(file);
+		ret = create_prefix_symbols(file);
 		if (ret)
 			goto out;
 	}
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index e1daae0630be..4bb7ce994b6a 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -942,23 +942,6 @@ struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec)
 	return sym;
 }
 
-struct symbol *
-elf_create_prefix_symbol(struct elf *elf, struct symbol *orig, size_t size)
-{
-	size_t namelen = strlen(orig->name) + sizeof("__pfx_");
-	char name[SYM_NAME_LEN];
-	unsigned long offset;
-
-	snprintf(name, namelen, "__pfx_%s", orig->name);
-
-	offset = orig->sym.st_value - size;
-
-	return elf_create_symbol(elf, name, orig->sec,
-				 GELF_ST_BIND(orig->sym.st_info),
-				 GELF_ST_TYPE(orig->sym.st_info),
-				 offset, size);
-}
-
 struct reloc *elf_init_reloc(struct elf *elf, struct section *rsec,
 			     unsigned int reloc_idx, unsigned long offset,
 			     struct symbol *sym, s64 addend, unsigned int type)
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index e2cd817fca52..60f844e43c5a 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -148,8 +148,6 @@ struct symbol *elf_create_symbol(struct elf *elf, const char *name,
 				 unsigned int type, unsigned long offset,
 				 size_t size);
 struct symbol *elf_create_section_symbol(struct elf *elf, struct section *sec);
-struct symbol *elf_create_prefix_symbol(struct elf *elf, struct symbol *orig,
-					size_t size);
 
 void *elf_add_data(struct elf *elf, struct section *sec, const void *data,
 		   size_t size);
-- 
cgit v1.2.3


From 164c9201e1dad8d5c0c38f583dba81e4b6da9cc7 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:04:03 -0700
Subject: objtool: Add base objtool support for livepatch modules

In preparation for klp-build, enable "classic" objtool to work on
livepatch modules:

  - Avoid duplicate symbol/section warnings for prefix symbols and the
    .static_call_sites and __mcount_loc sections which may have already
    been extracted by klp diff.

  - Add __klp_funcs to the IBT function pointer section whitelist.

  - Prevent KLP symbols from getting incorrectly classified as cold
    subfunctions.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/check.c                   | 52 +++++++++++++++++++++++++++++----
 tools/objtool/elf.c                     |  5 +++-
 tools/objtool/include/objtool/elf.h     |  1 +
 tools/objtool/include/objtool/objtool.h |  2 +-
 4 files changed, 53 insertions(+), 7 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b2659fbf7bc9..d071fbf73e4c 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
  */
 
+#define _GNU_SOURCE /* memmem() */
 #include <string.h>
 #include <stdlib.h>
 #include <inttypes.h>
@@ -611,6 +612,20 @@ static int init_pv_ops(struct objtool_file *file)
 	return 0;
 }
 
+static bool is_livepatch_module(struct objtool_file *file)
+{
+	struct section *sec;
+
+	if (!opts.module)
+		return false;
+
+	sec = find_section_by_name(file->elf, ".modinfo");
+	if (!sec)
+		return false;
+
+	return memmem(sec->data->d_buf, sec_size(sec), "\0livepatch=Y", 12);
+}
+
 static int create_static_call_sections(struct objtool_file *file)
 {
 	struct static_call_site *site;
@@ -622,7 +637,14 @@ static int create_static_call_sections(struct objtool_file *file)
 
 	sec = find_section_by_name(file->elf, ".static_call_sites");
 	if (sec) {
-		WARN("file already has .static_call_sites section, skipping");
+		/*
+		 * Livepatch modules may have already extracted the static call
+		 * site entries to take advantage of vmlinux static call
+		 * privileges.
+		 */
+		if (!file->klp)
+			WARN("file already has .static_call_sites section, skipping");
+
 		return 0;
 	}
 
@@ -666,7 +688,7 @@ static int create_static_call_sections(struct objtool_file *file)
 
 		key_sym = find_symbol_by_name(file->elf, tmp);
 		if (!key_sym) {
-			if (!opts.module) {
+			if (!opts.module || file->klp) {
 				ERROR("static_call: can't find static_call_key symbol: %s", tmp);
 				return -1;
 			}
@@ -885,7 +907,13 @@ static int create_mcount_loc_sections(struct objtool_file *file)
 
 	sec = find_section_by_name(file->elf, "__mcount_loc");
 	if (sec) {
-		WARN("file already has __mcount_loc section, skipping");
+		/*
+		 * Livepatch modules have already extracted their __mcount_loc
+		 * entries to cover the !CONFIG_FTRACE_MCOUNT_USE_OBJTOOL case.
+		 */
+		if (!file->klp)
+			WARN("file already has __mcount_loc section, skipping");
+
 		return 0;
 	}
 
@@ -2569,6 +2597,8 @@ static bool validate_branch_enabled(void)
 
 static int decode_sections(struct objtool_file *file)
 {
+	file->klp = is_livepatch_module(file);
+
 	mark_rodata(file);
 
 	if (init_pv_ops(file))
@@ -4244,6 +4274,9 @@ static bool ignore_unreachable_insn(struct objtool_file *file, struct instructio
  *   - compiler cloned functions (*.cold, *.part0, etc)
  *   - asm functions created with inline asm or without SYM_FUNC_START()
  *
+ * Also, the function may already have a prefix from a previous objtool run
+ * (livepatch extracted functions, or manually running objtool multiple times).
+ *
  * So return 0 if the NOPs are missing or the function already has a prefix
  * symbol.
  */
@@ -4266,6 +4299,14 @@ static int create_prefix_symbol(struct objtool_file *file, struct symbol *func)
 	if (snprintf_check(name, SYM_NAME_LEN, "__pfx_%s", func->name))
 		return -1;
 
+	if (file->klp) {
+		struct symbol *pfx;
+
+		pfx = find_symbol_by_offset(func->sec, func->offset - opts.prefix);
+		if (pfx && is_prefix_func(pfx) && !strcmp(pfx->name, name))
+			return 0;
+	}
+
 	insn = find_insn(file, func->sec, func->offset);
 	if (!insn) {
 		WARN("%s: can't find starting instruction", func->name);
@@ -4618,6 +4659,7 @@ static int validate_ibt(struct objtool_file *file)
 		    !strncmp(sec->name, ".debug", 6)			||
 		    !strcmp(sec->name, ".altinstructions")		||
 		    !strcmp(sec->name, ".ibt_endbr_seal")		||
+		    !strcmp(sec->name, ".kcfi_traps")			||
 		    !strcmp(sec->name, ".orc_unwind_ip")		||
 		    !strcmp(sec->name, ".retpoline_sites")		||
 		    !strcmp(sec->name, ".smp_locks")			||
@@ -4627,12 +4669,12 @@ static int validate_ibt(struct objtool_file *file)
 		    !strcmp(sec->name, "__bug_table")			||
 		    !strcmp(sec->name, "__ex_table")			||
 		    !strcmp(sec->name, "__jump_table")			||
+		    !strcmp(sec->name, "__klp_funcs")			||
 		    !strcmp(sec->name, "__mcount_loc")			||
-		    !strcmp(sec->name, ".kcfi_traps")			||
 		    !strcmp(sec->name, ".llvm.call-graph-profile")	||
 		    !strcmp(sec->name, ".llvm_bb_addr_map")		||
 		    !strcmp(sec->name, "__tracepoints")			||
-		    strstr(sec->name, "__patchable_function_entries"))
+		    !strcmp(sec->name, "__patchable_function_entries"))
 			continue;
 
 		for_each_reloc(sec->rsec, reloc)
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 4bb7ce994b6a..5feeefc7fc8f 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -499,7 +499,10 @@ static int elf_add_symbol(struct elf *elf, struct symbol *sym)
 	     strstarts(sym->name, "__pi___cfi_")))
 		sym->prefix = 1;
 
-	if (is_func_sym(sym) && strstr(sym->name, ".cold"))
+	if (strstarts(sym->name, ".klp.sym"))
+		sym->klp = 1;
+
+	if (!sym->klp && is_func_sym(sym) && strstr(sym->name, ".cold"))
 		sym->cold = 1;
 	sym->pfunc = sym->cfunc = sym;
 
diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
index 60f844e43c5a..21d8b825fd8f 100644
--- a/tools/objtool/include/objtool/elf.h
+++ b/tools/objtool/include/objtool/elf.h
@@ -88,6 +88,7 @@ struct symbol {
 	u8 debug_checksum    : 1;
 	u8 changed	     : 1;
 	u8 included	     : 1;
+	u8 klp		     : 1;
 	struct list_head pv_target;
 	struct reloc *relocs;
 	struct section *group_sec;
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index 7f70b41d1b8d..f7051bbe0bcb 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -28,7 +28,7 @@ struct objtool_file {
 	struct list_head mcount_loc_list;
 	struct list_head endbr_list;
 	struct list_head call_list;
-	bool ignore_unreachables, hints, rodata;
+	bool ignore_unreachables, hints, rodata, klp;
 
 	unsigned int nr_endbr;
 	unsigned int nr_endbr_int;
-- 
cgit v1.2.3


From 24ebfcd65a871df4555b98c49c9ed9a92f146113 Mon Sep 17 00:00:00 2001
From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Wed, 17 Sep 2025 09:04:08 -0700
Subject: livepatch/klp-build: Introduce klp-build script for generating
 livepatch modules

Add a klp-build script which automates the generation of a livepatch
module from a source .patch file by performing the following steps:

  - Builds an original kernel with -function-sections and
    -fdata-sections, plus objtool function checksumming.

  - Applies the .patch file and rebuilds the kernel using the same
    options.

  - Runs 'objtool klp diff' to detect changed functions and generate
    intermediate binary diff objects.

  - Builds a kernel module which links the diff objects with some
    livepatch module init code (scripts/livepatch/init.c).

  - Finalizes the livepatch module (aka work around linker wreckage)
    using 'objtool klp post-link'.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
 tools/objtool/klp-diff.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'tools/objtool')

diff --git a/tools/objtool/klp-diff.c b/tools/objtool/klp-diff.c
index 817d44394a78..4d1f9e9977eb 100644
--- a/tools/objtool/klp-diff.c
+++ b/tools/objtool/klp-diff.c
@@ -241,10 +241,12 @@ static struct symbol *next_file_symbol(struct elf *elf, struct symbol *sym)
 static bool is_uncorrelated_static_local(struct symbol *sym)
 {
 	static const char * const vars[] = {
-		"__key.",
-		"__warned.",
 		"__already_done.",
 		"__func__.",
+		"__key.",
+		"__warned.",
+		"_entry.",
+		"_entry_ptr.",
 		"_rs.",
 		"descriptor.",
 		"CSWTCH.",
-- 
cgit v1.2.3