Merge tag 'objtool-core-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool updates from Ingo Molnar:

 - klp-build livepatch module generation (Josh Poimboeuf)

   Introduce new objtool features and a klp-build script to generate
   livepatch modules using a source .patch as input.

   This builds on concepts from the longstanding out-of-tree kpatch
   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 which injects #line directives into the source .patch to
      preserve the original line numbers at compile time.

 - Disassemble code with libopcodes instead of running objdump
   (Alexandre Chartre)

 - Disassemble support (-d option to objtool) by Alexandre Chartre,
   which supports the decoding of various Linux kernel code generation
   specials such as alternatives:

      17ef:  sched_balance_find_dst_group+0x62f                 mov    0x34(%r9),%edx
      17f3:  sched_balance_find_dst_group+0x633               | <alternative.17f3>             | X86_FEATURE_POPCNT
      17f3:  sched_balance_find_dst_group+0x633               | call   0x17f8 <__sw_hweight64> | popcnt %rdi,%rax
      17f8:  sched_balance_find_dst_group+0x638                 cmp    %eax,%edx

   ... jump table alternatives:

      1895:  sched_use_asym_prio+0x5                            test   $0x8,%ch
      1898:  sched_use_asym_prio+0x8                            je     0x18a9 <sched_use_asym_prio+0x19>
      189a:  sched_use_asym_prio+0xa                          | <jump_table.189a>                        | JUMP
      189a:  sched_use_asym_prio+0xa                          | jmp    0x18ae <sched_use_asym_prio+0x1e> | nop2
      189c:  sched_use_asym_prio+0xc                            mov    $0x1,%eax
      18a1:  sched_use_asym_prio+0x11                           and    $0x80,%ecx

   ... exception table alternatives:

    native_read_msr:
      5b80:  native_read_msr+0x0                                                     mov    %edi,%ecx
      5b82:  native_read_msr+0x2                                                   | <ex_table.5b82> | EXCEPTION
      5b82:  native_read_msr+0x2                                                   | rdmsr           | resume at 0x5b84 <native_read_msr+0x4>
      5b84:  native_read_msr+0x4                                                     shl    $0x20,%rdx

   .... x86 feature flag decoding (also see the X86_FEATURE_POPCNT
        example in sched_balance_find_dst_group() above):

      2faaf:  start_thread_common.constprop.0+0x1f                                    jne    0x2fba4 <start_thread_common.constprop.0+0x114>
      2fab5:  start_thread_common.constprop.0+0x25                                  | <alternative.2fab5>                  | X86_FEATURE_ALWAYS                                  | X86_BUG_NULL_SEG
      2fab5:  start_thread_common.constprop.0+0x25                                  | jmp    0x2faba <.altinstr_aux+0x2f4> | jmp    0x4b0 <start_thread_common.constprop.0+0x3f> | nop5
      2faba:  start_thread_common.constprop.0+0x2a                                    mov    $0x2b,%eax

   ... NOP sequence shortening:

      1048e2:  snapshot_write_finalize+0xc2                                            je     0x104917 <snapshot_write_finalize+0xf7>
      1048e4:  snapshot_write_finalize+0xc4                                            nop6
      1048ea:  snapshot_write_finalize+0xca                                            nop11
      1048f5:  snapshot_write_finalize+0xd5                                            nop11
      104900:  snapshot_write_finalize+0xe0                                            mov    %rax,%rcx
      104903:  snapshot_write_finalize+0xe3                                            mov    0x10(%rdx),%rax

   ... and much more.

 - Function validation tracing support (Alexandre Chartre)

 - Various -ffunction-sections fixes (Josh Poimboeuf)

 - Clang AutoFDO (Automated Feedback-Directed Optimizations) support
   (Josh Poimboeuf)

 - Misc fixes and cleanups (Borislav Petkov, Chen Ni, Dylan Hatch, Ingo
   Molnar, John Wang, Josh Poimboeuf, Pankaj Raghav, Peter Zijlstra,
   Thorsten Blum)

* tag 'objtool-core-2025-12-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits)
  objtool: Fix segfault on unknown alternatives
  objtool: Build with disassembly can fail when including bdf.h
  objtool: Trim trailing NOPs in alternative
  objtool: Add wide output for disassembly
  objtool: Compact output for alternatives with one instruction
  objtool: Improve naming of group alternatives
  objtool: Add Function to get the name of a CPU feature
  objtool: Provide access to feature and flags of group alternatives
  objtool: Fix address references in alternatives
  objtool: Disassemble jump table alternatives
  objtool: Disassemble exception table alternatives
  objtool: Print addresses with alternative instructions
  objtool: Disassemble group alternatives
  objtool: Print headers for alternatives
  objtool: Preserve alternatives order
  objtool: Add the --disas=<function-pattern> action
  objtool: Do not validate IBT for .return_sites and .call_sites
  objtool: Improve tracing of alternative instructions
  objtool: Add functions to better name alternatives
  objtool: Identify the different types of alternatives
  ...

1 files changed, 134 insertions, 0 deletions

diff --git a/include/linux/annotate.h b/include/linux/annotate.h
new file mode 100644
index 000000000000..7c10d34d198c
--- /dev/null
+++ b/include/linux/annotate.h
@@ -0,0 +1,134 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_ANNOTATE_H
+#define _LINUX_ANNOTATE_H
+
+#include <linux/objtool_types.h>
+
+#ifdef CONFIG_OBJTOOL
+
+#ifndef __ASSEMBLY__
+
+#define __ASM_ANNOTATE(section, label, type)				\
+	".pushsection " section ",\"M\", @progbits, 8\n\t"		\
+	".long " __stringify(label) " - .\n\t"				\
+	".long " __stringify(type) "\n\t"				\
+	".popsection\n\t"
+
+#define ASM_ANNOTATE_LABEL(label, type)					\
+	__ASM_ANNOTATE(".discard.annotate_insn", label, type)
+
+#define ASM_ANNOTATE(type)						\
+	"911:\n\t"							\
+	ASM_ANNOTATE_LABEL(911b, type)
+
+#define ASM_ANNOTATE_DATA(type)						\
+	"912:\n\t"							\
+	__ASM_ANNOTATE(".discard.annotate_data", 912b, type)
+
+#else /* __ASSEMBLY__ */
+
+.macro __ANNOTATE section, type
+.Lhere_\@:
+	.pushsection \section, "M", @progbits, 8
+	.long	.Lhere_\@ - .
+	.long	\type
+	.popsection
+.endm
+
+.macro ANNOTATE type
+	__ANNOTATE ".discard.annotate_insn", \type
+.endm
+
+.macro ANNOTATE_DATA type
+	__ANNOTATE ".discard.annotate_data", \type
+.endm
+
+#endif /* __ASSEMBLY__ */
+
+#else /* !CONFIG_OBJTOOL */
+#ifndef __ASSEMBLY__
+#define ASM_ANNOTATE_LABEL(label, type) ""
+#define ASM_ANNOTATE(type)
+#define ASM_ANNOTATE_DATA(type)
+#else /* __ASSEMBLY__ */
+.macro ANNOTATE type
+.endm
+.macro ANNOTATE_DATA type
+.endm
+#endif /* __ASSEMBLY__ */
+#endif /* !CONFIG_OBJTOOL */
+
+#ifndef __ASSEMBLY__
+
+/*
+ * Annotate away the various 'relocation to !ENDBR` complaints; knowing that
+ * these relocations will never be used for indirect calls.
+ */
+#define ANNOTATE_NOENDBR		ASM_ANNOTATE(ANNOTYPE_NOENDBR)
+#define ANNOTATE_NOENDBR_SYM(sym)	asm(ASM_ANNOTATE_LABEL(sym, ANNOTYPE_NOENDBR))
+
+/*
+ * This should be used immediately before an indirect jump/call. It tells
+ * objtool the subsequent indirect jump/call is vouched safe for retpoline
+ * builds.
+ */
+#define ANNOTATE_RETPOLINE_SAFE		ASM_ANNOTATE(ANNOTYPE_RETPOLINE_SAFE)
+/*
+ * See linux/instrumentation.h
+ */
+#define ANNOTATE_INSTR_BEGIN(label)	ASM_ANNOTATE_LABEL(label, ANNOTYPE_INSTR_BEGIN)
+#define ANNOTATE_INSTR_END(label)	ASM_ANNOTATE_LABEL(label, ANNOTYPE_INSTR_END)
+/*
+ * objtool annotation to ignore the alternatives and only consider the original
+ * instruction(s).
+ */
+#define ANNOTATE_IGNORE_ALTERNATIVE	ASM_ANNOTATE(ANNOTYPE_IGNORE_ALTS)
+/*
+ * This macro indicates that the following intra-function call is valid.
+ * Any non-annotated intra-function call will cause objtool to issue a warning.
+ */
+#define ANNOTATE_INTRA_FUNCTION_CALL	ASM_ANNOTATE(ANNOTYPE_INTRA_FUNCTION_CALL)
+/*
+ * Use objtool to validate the entry requirement that all code paths do
+ * VALIDATE_UNRET_END before RET.
+ *
+ * NOTE: The macro must be used at the beginning of a global symbol, otherwise
+ * it will be ignored.
+ */
+#define ANNOTATE_UNRET_BEGIN		ASM_ANNOTATE(ANNOTYPE_UNRET_BEGIN)
+/*
+ * This should be used to refer to an instruction that is considered
+ * terminating, like a noreturn CALL or UD2 when we know they are not -- eg
+ * WARN using UD2.
+ */
+#define ANNOTATE_REACHABLE(label)	ASM_ANNOTATE_LABEL(label, ANNOTYPE_REACHABLE)
+/*
+ * This should not be used; it annotates away CFI violations. There are a few
+ * valid use cases like kexec handover to the next kernel image, and there is
+ * no security concern there.
+ *
+ * There are also a few real issues annotated away, like EFI because we can't
+ * control the EFI code.
+ */
+#define ANNOTATE_NOCFI_SYM(sym)		asm(ASM_ANNOTATE_LABEL(sym, ANNOTYPE_NOCFI))
+
+/*
+ * Annotate a special section entry.  This emables livepatch module generation
+ * to find and extract individual special section entries as needed.
+ */
+#define ANNOTATE_DATA_SPECIAL		ASM_ANNOTATE_DATA(ANNOTYPE_DATA_SPECIAL)
+
+#else /* __ASSEMBLY__ */
+#define ANNOTATE_NOENDBR		ANNOTATE type=ANNOTYPE_NOENDBR
+#define ANNOTATE_RETPOLINE_SAFE		ANNOTATE type=ANNOTYPE_RETPOLINE_SAFE
+/*	ANNOTATE_INSTR_BEGIN		ANNOTATE type=ANNOTYPE_INSTR_BEGIN */
+/*	ANNOTATE_INSTR_END		ANNOTATE type=ANNOTYPE_INSTR_END */
+#define ANNOTATE_IGNORE_ALTERNATIVE	ANNOTATE type=ANNOTYPE_IGNORE_ALTS
+#define ANNOTATE_INTRA_FUNCTION_CALL	ANNOTATE type=ANNOTYPE_INTRA_FUNCTION_CALL
+#define ANNOTATE_UNRET_BEGIN		ANNOTATE type=ANNOTYPE_UNRET_BEGIN
+#define ANNOTATE_REACHABLE		ANNOTATE type=ANNOTYPE_REACHABLE
+#define ANNOTATE_NOCFI_SYM		ANNOTATE type=ANNOTYPE_NOCFI
+#define ANNOTATE_DATA_SPECIAL		ANNOTATE_DATA type=ANNOTYPE_DATA_SPECIAL
+#endif /* __ASSEMBLY__ */
+
+#endif /* _LINUX_ANNOTATE_H */