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
  ...

4 files changed, 39 insertions, 39 deletions

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 8ee5ff547357..d19a3fd7cf04 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -2244,21 +2244,34 @@ int alternatives_text_reserved(void *start, void *end)
  * See entry_{32,64}.S for more details.
  */
 
-/*
- * We define the int3_magic() function in assembly to control the calling
- * convention such that we can 'call' it from assembly.
- */
+extern void int3_selftest_asm(unsigned int *ptr);
 
-extern void int3_magic(unsigned int *ptr); /* defined in asm */
+asm (
+"	.pushsection	.init.text, \"ax\", @progbits\n"
+"	.type		int3_selftest_asm, @function\n"
+"int3_selftest_asm:\n"
+	ANNOTATE_NOENDBR
+	/*
+	 * INT3 padded with NOP to CALL_INSN_SIZE. The INT3 triggers an
+	 * exception, then the int3_exception_nb notifier emulates a call to
+	 * int3_selftest_callee().
+	 */
+"	int3; nop; nop; nop; nop\n"
+	ASM_RET
+"	.size		int3_selftest_asm, . - int3_selftest_asm\n"
+"	.popsection\n"
+);
+
+extern void int3_selftest_callee(unsigned int *ptr);
 
 asm (
 "	.pushsection	.init.text, \"ax\", @progbits\n"
-"	.type		int3_magic, @function\n"
-"int3_magic:\n"
+"	.type		int3_selftest_callee, @function\n"
+"int3_selftest_callee:\n"
 	ANNOTATE_NOENDBR
-"	movl	$1, (%" _ASM_ARG1 ")\n"
+"	movl	$0x1234, (%" _ASM_ARG1 ")\n"
 	ASM_RET
-"	.size		int3_magic, .-int3_magic\n"
+"	.size		int3_selftest_callee, . - int3_selftest_callee\n"
 "	.popsection\n"
 );
 
@@ -2267,7 +2280,7 @@ extern void int3_selftest_ip(void); /* defined in asm below */
 static int __init
 int3_exception_notify(struct notifier_block *self, unsigned long val, void *data)
 {
-	unsigned long selftest = (unsigned long)&int3_selftest_ip;
+	unsigned long selftest = (unsigned long)&int3_selftest_asm;
 	struct die_args *args = data;
 	struct pt_regs *regs = args->regs;
 
@@ -2282,7 +2295,7 @@ int3_exception_notify(struct notifier_block *self, unsigned long val, void *data
 	if (regs->ip - INT3_INSN_SIZE != selftest)
 		return NOTIFY_DONE;
 
-	int3_emulate_call(regs, (unsigned long)&int3_magic);
+	int3_emulate_call(regs, (unsigned long)&int3_selftest_callee);
 	return NOTIFY_STOP;
 }
 
@@ -2298,19 +2311,11 @@ static noinline void __init int3_selftest(void)
 	BUG_ON(register_die_notifier(&int3_exception_nb));
 
 	/*
-	 * Basically: int3_magic(&val); but really complicated :-)
-	 *
-	 * INT3 padded with NOP to CALL_INSN_SIZE. The int3_exception_nb
-	 * notifier above will emulate CALL for us.
+	 * Basically: int3_selftest_callee(&val); but really complicated :-)
 	 */
-	asm volatile ("int3_selftest_ip:\n\t"
-		      ANNOTATE_NOENDBR
-		      "    int3; nop; nop; nop; nop\n\t"
-		      : ASM_CALL_CONSTRAINT
-		      : __ASM_SEL_RAW(a, D) (&val)
-		      : "memory");
-
-	BUG_ON(val != 1);
+	int3_selftest_asm(&val);
+
+	BUG_ON(val != 0x1234);
 
 	unregister_die_notifier(&int3_exception_nb);
 }
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c
index 0aabd4c4e2c4..6f826a00eca2 100644
--- a/arch/x86/kernel/kprobes/opt.c
+++ b/arch/x86/kernel/kprobes/opt.c
@@ -103,7 +103,6 @@ static void synthesize_set_arg1(kprobe_opcode_t *addr, unsigned long val)
 
 asm (
 			".pushsection .rodata\n"
-			"optprobe_template_func:\n"
 			".global optprobe_template_entry\n"
 			"optprobe_template_entry:\n"
 #ifdef CONFIG_X86_64
@@ -160,9 +159,6 @@ asm (
 			"optprobe_template_end:\n"
 			".popsection\n");
 
-void optprobe_template_func(void);
-STACK_FRAME_NON_STANDARD(optprobe_template_func);
-
 #define TMPL_CLAC_IDX \
 	((long)optprobe_template_clac - (long)optprobe_template_entry)
 #define TMPL_MOVE_IDX \
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 0ffbae902e2f..11c45ce42694 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -97,6 +97,7 @@ static int __write_relocate_add(Elf64_Shdr *sechdrs,
 	DEBUGP("%s relocate section %u to %u\n",
 	       apply ? "Applying" : "Clearing",
 	       relsec, sechdrs[relsec].sh_info);
+
 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
 		size_t size;
 
@@ -162,15 +163,17 @@ static int __write_relocate_add(Elf64_Shdr *sechdrs,
 
 		if (apply) {
 			if (memcmp(loc, &zero, size)) {
-				pr_err("x86/modules: Invalid relocation target, existing value is nonzero for type %d, loc %p, val %Lx\n",
-				       (int)ELF64_R_TYPE(rel[i].r_info), loc, val);
+				pr_err("x86/modules: Invalid relocation target, existing value is nonzero for sec %u, idx %u, type %d, loc %lx, val %llx\n",
+				       relsec, i, (int)ELF64_R_TYPE(rel[i].r_info),
+				       (unsigned long)loc, val);
 				return -ENOEXEC;
 			}
 			write(loc, &val, size);
 		} else {
 			if (memcmp(loc, &val, size)) {
-				pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for type %d, loc %p, val %Lx\n",
-					(int)ELF64_R_TYPE(rel[i].r_info), loc, val);
+				pr_warn("x86/modules: Invalid relocation target, existing value does not match expected value for sec %u, idx %u, type %d, loc %lx, val %llx\n",
+					relsec, i, (int)ELF64_R_TYPE(rel[i].r_info),
+					(unsigned long)loc, val);
 				return -ENOEXEC;
 			}
 			write(loc, &zero, size);
@@ -179,8 +182,8 @@ static int __write_relocate_add(Elf64_Shdr *sechdrs,
 	return 0;
 
 overflow:
-	pr_err("overflow in relocation type %d val %Lx\n",
-	       (int)ELF64_R_TYPE(rel[i].r_info), val);
+	pr_err("overflow in relocation type %d val %llx sec %u idx %d\n",
+	       (int)ELF64_R_TYPE(rel[i].r_info), val, relsec, i);
 	pr_err("`%s' likely not compiled with -mcmodel=kernel\n",
 	       me->name);
 	return -ENOEXEC;
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index eb289abece23..a4ba735842a8 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1328,11 +1328,7 @@ void __noreturn hlt_play_dead(void)
 		native_halt();
 }
 
-/*
- * native_play_dead() is essentially a __noreturn function, but it can't
- * be marked as such as the compiler may complain about it.
- */
-void native_play_dead(void)
+void __noreturn native_play_dead(void)
 {
 	if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS))
 		__update_spec_ctrl(0);
@@ -1351,7 +1347,7 @@ int native_cpu_disable(void)
 	return -ENOSYS;
 }
 
-void native_play_dead(void)
+void __noreturn native_play_dead(void)
 {
 	BUG();
 }