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>

1 files changed, 43 insertions, 3 deletions

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;
 }