Merge tag 'objtool-urgent-2025-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull objtool fixes from Ingo Molnar:
"Address various objtool scalability bugs/inefficiencies exposed by
allmodconfig builds, plus improve the quality of alternatives
instructions generated code and disassembly"

* tag 'objtool-urgent-2025-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Simplify .annotate_insn code generation output some more
objtool: Add more robust signal error handling, detect and warn about stack overflows
objtool: Remove newlines and tabs from annotation macros
objtool: Consolidate annotation macros
x86/asm: Remove ANNOTATE_DATA_SPECIAL usage
x86/alternative: Remove ANNOTATE_DATA_SPECIAL usage
objtool: Fix stack overflow in validate_branch()

arch/um/include/asm/Kbuild

···
 generic-y += dma-mapping.h
 generic-y += emergency-restart.h
 generic-y += exec.h
-generic-y += extable.h
 generic-y += ftrace.h
 generic-y += hw_irq.h
 generic-y += irq_regs.h

arch/um/kernel/asm-offsets.c

···
 #include <linux/fs.h>
 #include <asm/mman.h>
 #include <asm/seccomp.h>
+#include <asm/extable.h>
 
 /* workaround for a warning with -Wmissing-prototypes */
 void foo(void);
···
 	DEFINE(HOSTFS_ATTR_CTIME, ATTR_CTIME);
 	DEFINE(HOSTFS_ATTR_ATIME_SET, ATTR_ATIME_SET);
 	DEFINE(HOSTFS_ATTR_MTIME_SET, ATTR_MTIME_SET);
+
+	DEFINE(ALT_INSTR_SIZE, sizeof(struct alt_instr));
+	DEFINE(EXTABLE_SIZE,   sizeof(struct exception_table_entry));
 }

arch/x86/include/asm/alternative.h

···
 	"773:\n"
 
 #define ALTINSTR_ENTRY(ft_flags)					      \
-	".pushsection .altinstructions,\"a\"\n"				      \
-	ANNOTATE_DATA_SPECIAL						      \
+	".pushsection .altinstructions, \"aM\", @progbits, "		      \
+		      __stringify(ALT_INSTR_SIZE) "\n"			      \
 	" .long 771b - .\n"				/* label           */ \
 	" .long 774f - .\n"				/* new instruction */ \
 	" .4byte " __stringify(ft_flags) "\n"		/* feature + flags */ \
···
 
 #define ALTINSTR_REPLACEMENT(newinstr)		/* replacement */	\
 	".pushsection .altinstr_replacement, \"ax\"\n"			\
-	ANNOTATE_DATA_SPECIAL						\
+	ANNOTATE_DATA_SPECIAL "\n"					\
 	"# ALT: replacement\n"						\
 	"774:\n\t" newinstr "\n775:\n"					\
 	".popsection\n"
···
  * instruction. See apply_alternatives().
  */
 .macro altinstr_entry orig alt ft_flags orig_len alt_len
-	ANNOTATE_DATA_SPECIAL
 	.long \orig - .
 	.long \alt - .
 	.4byte \ft_flags
···
 741:									\
 	.skip -(((744f-743f)-(741b-740b)) > 0) * ((744f-743f)-(741b-740b)),0x90	;\
 742:									\
-	.pushsection .altinstructions,"a" ;				\
+	.pushsection .altinstructions, "aM", @progbits, ALT_INSTR_SIZE ;\
 	altinstr_entry 740b,743f,flag,742b-740b,744f-743f ;		\
 	.popsection ;							\
 	.pushsection .altinstr_replacement,"ax"	;			\

arch/x86/include/asm/asm.h

···
 
 #ifdef __KERNEL__
 
+#ifndef COMPILE_OFFSETS
+#include <asm/asm-offsets.h>
+#endif
+
 # include <asm/extable_fixup_types.h>
 
 /* Exception table entry */
 #ifdef __ASSEMBLER__
 
-# define _ASM_EXTABLE_TYPE(from, to, type)			\
-	.pushsection "__ex_table","a" ;				\
-	.balign 4 ;						\
-	ANNOTATE_DATA_SPECIAL ;					\
-	.long (from) - . ;					\
-	.long (to) - . ;					\
-	.long type ;						\
+# define _ASM_EXTABLE_TYPE(from, to, type)				\
+	.pushsection "__ex_table", "aM", @progbits, EXTABLE_SIZE ;	\
+	.balign 4 ;							\
+	.long (from) - . ;						\
+	.long (to) - . ;						\
+	.long type ;							\
 	.popsection
 
 # ifdef CONFIG_KPROBES
···
 	".purgem extable_type_reg\n"
 
 # define _ASM_EXTABLE_TYPE(from, to, type)			\
-	" .pushsection \"__ex_table\",\"a\"\n"			\
+	" .pushsection __ex_table, \"aM\", @progbits, "		\
+		       __stringify(EXTABLE_SIZE) "\n"		\
 	" .balign 4\n"						\
-	ANNOTATE_DATA_SPECIAL					\
 	" .long (" #from ") - .\n"				\
 	" .long (" #to ") - .\n"				\
 	" .long " __stringify(type) " \n"			\
 	" .popsection\n"
 
 # define _ASM_EXTABLE_TYPE_REG(from, to, type, reg)				\
-	" .pushsection \"__ex_table\",\"a\"\n"					\
+	" .pushsection __ex_table, \"aM\", @progbits, "				\
+		       __stringify(EXTABLE_SIZE) "\n"				\
 	" .balign 4\n"								\
-	ANNOTATE_DATA_SPECIAL							\
 	" .long (" #from ") - .\n"						\
 	" .long (" #to ") - .\n"						\
 	DEFINE_EXTABLE_TYPE_REG							\

arch/x86/include/asm/bug.h

···
 
 #define _BUG_FLAGS_ASM(format, file, line, flags, size, extra)		\
 	".pushsection __bug_table,\"aw\"\n\t"				\
-	ANNOTATE_DATA_SPECIAL						\
+	ANNOTATE_DATA_SPECIAL "\n\t"					\
 	"2:\n\t"							\
 	__BUG_ENTRY(format, file, line, flags)				\
 	"\t.org 2b + " size "\n"					\

arch/x86/include/asm/cpufeature.h

···
 	asm goto(ALTERNATIVE_TERNARY("jmp 6f", %c[feature], "", "jmp %l[t_no]")
 		".pushsection .altinstr_aux,\"ax\"\n"
 		"6:\n"
-		ANNOTATE_DATA_SPECIAL
+		ANNOTATE_DATA_SPECIAL "\n"
 		" testb %[bitnum], %a[cap_byte]\n"
 		" jnz %l[t_yes]\n"
 		" jmp %l[t_no]\n"

arch/x86/include/asm/irq_stack.h

···
 
 #define ASM_CALL_ARG0							\
 	"1: call %c[__func]				\n"		\
-	ANNOTATE_REACHABLE(1b)
+	ANNOTATE_REACHABLE(1b) "			\n"
 
 #define ASM_CALL_ARG1							\
 	"movq	%[arg1], %%rdi				\n"		\

arch/x86/include/asm/jump_label.h

···
 #define JUMP_TABLE_ENTRY(key, label)			\
 	".pushsection __jump_table,  \"aw\" \n\t"	\
 	_ASM_ALIGN "\n\t"				\
-	ANNOTATE_DATA_SPECIAL				\
+	ANNOTATE_DATA_SPECIAL "\n"			\
 	".long 1b - . \n\t"				\
 	".long " label " - . \n\t"			\
 	_ASM_PTR " " key " - . \n\t"			\

arch/x86/include/asm/nospec-branch.h

···
  */
 # define CALL_NOSPEC						\
 	ALTERNATIVE_2(						\
-	ANNOTATE_RETPOLINE_SAFE					\
+	ANNOTATE_RETPOLINE_SAFE "\n"				\
 	"call *%[thunk_target]\n",				\
 	"       jmp    904f;\n"					\
 	"       .align 16\n"					\
···
 	"904:	call   901b;\n",				\
 	X86_FEATURE_RETPOLINE,					\
 	"lfence;\n"						\
-	ANNOTATE_RETPOLINE_SAFE					\
+	ANNOTATE_RETPOLINE_SAFE "\n"				\
 	"call *%[thunk_target]\n",				\
 	X86_FEATURE_RETPOLINE_LFENCE)
 

arch/x86/include/asm/paravirt_types.h

···
  * don't need to bother with CFI prefixes.
  */
 #define PARAVIRT_CALL					\
-	ANNOTATE_RETPOLINE_SAFE				\
+	ANNOTATE_RETPOLINE_SAFE "\n\t"			\
 	"call *%[paravirt_opptr];"
 
 /*

arch/x86/include/asm/smap.h

···
 	unsigned long flags;
 
 	asm volatile ("# smap_save\n\t"
-		      ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE
+		      ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE "\n\t"
 				  "", "pushf; pop %0; clac",
 				  X86_FEATURE_SMAP)
 		      : "=rm" (flags) : : "memory", "cc");
···
 static __always_inline void smap_restore(unsigned long flags)
 {
 	asm volatile ("# smap_restore\n\t"
-		      ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE
+		      ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE "\n\t"
 				  "", "push %0; popf",
 				  X86_FEATURE_SMAP)
 		      : : "g" (flags) : "memory", "cc");
···
 	ALTERNATIVE("", "stac", X86_FEATURE_SMAP)
 
 #define ASM_CLAC_UNSAFE \
-	ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "clac", X86_FEATURE_SMAP)
+	ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "\n\t" "clac", X86_FEATURE_SMAP)
 #define ASM_STAC_UNSAFE \
-	ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "stac", X86_FEATURE_SMAP)
+	ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "\n\t" "stac", X86_FEATURE_SMAP)
 
 #endif /* __ASSEMBLER__ */
 

arch/x86/include/asm/static_call.h

···
 	    ".align 4						\n"	\
 	    ".globl " STATIC_CALL_TRAMP_STR(name) "		\n"	\
 	    STATIC_CALL_TRAMP_STR(name) ":			\n"	\
-	    ANNOTATE_NOENDBR						\
+	    ANNOTATE_NOENDBR "					\n"	\
 	    insns "						\n"	\
 	    ".byte 0x0f, 0xb9, 0xcc				\n"	\
 	    ".type " STATIC_CALL_TRAMP_STR(name) ", @function	\n"	\

arch/x86/kernel/alternative.c

···
 "	.pushsection	.init.text, \"ax\", @progbits\n"
 "	.type		int3_selftest_asm, @function\n"
 "int3_selftest_asm:\n"
-	ANNOTATE_NOENDBR
+	ANNOTATE_NOENDBR "\n"
 	/*
 	 * INT3 padded with NOP to CALL_INSN_SIZE. The INT3 triggers an
 	 * exception, then the int3_exception_nb notifier emulates a call to
···
 "	.pushsection	.init.text, \"ax\", @progbits\n"
 "	.type		int3_selftest_callee, @function\n"
 "int3_selftest_callee:\n"
-	ANNOTATE_NOENDBR
+	ANNOTATE_NOENDBR "\n"
 "	movl	$0x1234, (%" _ASM_ARG1 ")\n"
 	ASM_RET
 "	.size		int3_selftest_callee, . - int3_selftest_callee\n"

arch/x86/kernel/asm-offsets.c

···
 	OFFSET(ARIA_CTX_rounds, aria_ctx, rounds);
 #endif
 
+	BLANK();
+	DEFINE(ALT_INSTR_SIZE,	sizeof(struct alt_instr));
+	DEFINE(EXTABLE_SIZE,	sizeof(struct exception_table_entry));
 }

arch/x86/kernel/rethook.c

···
 	".type arch_rethook_trampoline, @function\n"
 	"arch_rethook_trampoline:\n"
 #ifdef CONFIG_X86_64
-	ANNOTATE_NOENDBR	/* This is only jumped from ret instruction */
+	ANNOTATE_NOENDBR "\n"	/* This is only jumped from ret instruction */
 	/* Push a fake return address to tell the unwinder it's a rethook. */
 	"	pushq $arch_rethook_trampoline\n"
 	UNWIND_HINT_FUNC

arch/x86/kernel/static_call.c

···
      ".type __static_call_return, @function\n\t"
      ASM_FUNC_ALIGN "\n\t"
      "__static_call_return:\n\t"
-     ANNOTATE_NOENDBR
-     ANNOTATE_RETPOLINE_SAFE
+     ANNOTATE_NOENDBR "\n\t"
+     ANNOTATE_RETPOLINE_SAFE "\n\t"
      "ret; int3\n\t"
      ".size __static_call_return, . - __static_call_return \n\t");
 

arch/x86/lib/error-inject.c

···
 	".globl just_return_func\n"
 	ASM_FUNC_ALIGN
 	"just_return_func:\n"
-		ANNOTATE_NOENDBR
+		ANNOTATE_NOENDBR "\n"
 		ASM_RET
 	".size just_return_func, .-just_return_func\n"
 );

include/linux/annotate.h

···
 
 #ifdef CONFIG_OBJTOOL
 
+#define __ASM_ANNOTATE(section, label, type)				\
+	.pushsection section, "M", @progbits, 8;			\
+	.long label - ., type;						\
+	.popsection
+
 #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)
+	__stringify(__ASM_ANNOTATE(.discard.annotate_insn, label, type))
 
 #define ASM_ANNOTATE(type)						\
-	"911:\n\t"							\
-	ASM_ANNOTATE_LABEL(911b, type)
+	"911: "								\
+	__stringify(__ASM_ANNOTATE(.discard.annotate_insn, 911b, type))
 
 #define ASM_ANNOTATE_DATA(type)						\
-	"912:\n\t"							\
-	__ASM_ANNOTATE(".discard.annotate_data", 912b, type)
+	"912: "								\
+	__stringify(__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
+.Lhere_\@:
+	__ASM_ANNOTATE(.discard.annotate_insn, .Lhere_\@, \type)
 .endm
 
 .macro ANNOTATE_DATA type
-	__ANNOTATE ".discard.annotate_data", \type
+.Lhere_\@:
+	__ASM_ANNOTATE(.discard.annotate_data, .Lhere_\@, \type)
 .endm
 
 #endif /* __ASSEMBLY__ */

include/linux/objtool.h

···
 #define UNWIND_HINT(type, sp_reg, sp_offset, signal)		\
 	"987: \n\t"						\
 	".pushsection .discard.unwind_hints\n\t"		\
-	ANNOTATE_DATA_SPECIAL					\
+	ANNOTATE_DATA_SPECIAL "\n\t"				\
 	/* struct unwind_hint */				\
 	".long 987b - .\n\t"					\
 	".short " __stringify(sp_offset) "\n\t"			\

kernel/bounds.c

···
  */
 
 #define __GENERATING_BOUNDS_H
+#define COMPILE_OFFSETS
 /* Include headers that define the enum constants of interest */
 #include <linux/page-flags.h>
 #include <linux/mmzone.h>

scripts/mod/devicetable-offsets.c

···
 // SPDX-License-Identifier: GPL-2.0
+#define COMPILE_OFFSETS
 #include <linux/kbuild.h>
 #include <linux/mod_devicetable.h>
 

tools/objtool/Build

···
 objtool-y += libctype.o
 objtool-y += str_error_r.o
 objtool-y += librbtree.o
+objtool-y += signal.o
 
 $(OUTPUT)libstring.o: ../lib/string.c FORCE
 	$(call rule_mkdir)

tools/objtool/check.c

···
 	return 0;
 }
 
-static int handle_insn_ops(struct instruction *insn,
-			   struct instruction *next_insn,
-			   struct insn_state *state)
+static int noinline handle_insn_ops(struct instruction *insn,
+				    struct instruction *next_insn,
+				    struct insn_state *state)
 {
+	struct insn_state prev_state __maybe_unused = *state;
 	struct stack_op *op;
-	int ret;
+	int ret = 0;
 
 	for (op = insn->stack_ops; op; op = op->next) {
 
 		ret = update_cfi_state(insn, next_insn, &state->cfi, op);
 		if (ret)
-			return ret;
+			goto done;
 
 		if (!opts.uaccess || !insn->alt_group)
 			continue;
···
 				state->uaccess_stack = 1;
 			} else if (state->uaccess_stack >> 31) {
 				WARN_INSN(insn, "PUSHF stack exhausted");
-				return 1;
+				ret = 1;
+				goto done;
 			}
 			state->uaccess_stack <<= 1;
 			state->uaccess_stack  |= state->uaccess;
···
 		}
 	}
 
-	return 0;
+done:
+	TRACE_INSN_STATE(insn, &prev_state, state);
+
+	return ret;
 }
 
 static bool insn_cfi_match(struct instruction *insn, struct cfi_state *cfi2)
···
 			 struct instruction *prev_insn, struct instruction *next_insn,
 			 bool *dead_end)
 {
-	/* prev_state and alt_name are not used if there is no disassembly support */
-	struct insn_state prev_state __maybe_unused;
 	char *alt_name __maybe_unused = NULL;
 	struct alternative *alt;
 	u8 visited;
···
 	if (skip_alt_group(insn))
 		return 0;
 
-	prev_state = *statep;
-	ret = handle_insn_ops(insn, next_insn, statep);
-	TRACE_INSN_STATE(insn, &prev_state, statep);
-
-	if (ret)
+	if (handle_insn_ops(insn, next_insn, statep))
 		return 1;
 
 	switch (insn->type) {

tools/objtool/include/objtool/objtool.h

···
 
 char *top_level_dir(const char *file);
 
+int init_signal_handler(void);
+
 struct objtool_file *objtool_open_read(const char *_objname);
 
 int objtool_pv_add(struct objtool_file *file, int idx, struct symbol *func);

tools/objtool/objtool.c

···
 	return str;
 }
 
-
 int main(int argc, const char **argv)
 {
 	static const char *UNUSED = "OBJTOOL_NOT_IMPLEMENTED";
+
+	if (init_signal_handler())
+		return -1;
 
 	/* libsubcmd init */
 	exec_cmd_init("objtool", UNUSED, UNUSED, UNUSED);

tools/objtool/signal.c

···
+/*
+ * signal.c: Register a sigaltstack for objtool, to be able to
+ *	     run a signal handler on a separate stack even if
+ *	     the main process stack has overflown. Print out
+ *	     stack overflow errors when this happens.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/resource.h>
+#include <string.h>
+
+#include <objtool/objtool.h>
+#include <objtool/warn.h>
+
+static unsigned long stack_limit;
+
+static bool is_stack_overflow(void *fault_addr)
+{
+	unsigned long fault = (unsigned long)fault_addr;
+
+	/* Check if fault is in the guard page just below the limit. */
+	return fault < stack_limit && fault >= stack_limit - 4096;
+}
+
+static void signal_handler(int sig_num, siginfo_t *info, void *context)
+{
+	struct sigaction sa_dfl = {0};
+	const char *sig_name;
+	char msg[256];
+	int msg_len;
+
+	switch (sig_num) {
+	case SIGSEGV:	sig_name = "SIGSEGV";		break;
+	case SIGBUS:	sig_name = "SIGBUS";		break;
+	case SIGILL:	sig_name = "SIGILL";		break;
+	case SIGABRT:	sig_name = "SIGABRT";		break;
+	default:	sig_name = "Unknown signal";	break;
+	}
+
+	if (is_stack_overflow(info->si_addr)) {
+		msg_len = snprintf(msg, sizeof(msg),
+				   "%s: error: %s: objtool stack overflow!\n",
+				   objname, sig_name);
+	} else {
+		msg_len = snprintf(msg, sizeof(msg),
+				   "%s: error: %s: objtool crash!\n",
+				   objname, sig_name);
+	}
+
+	msg_len = write(STDERR_FILENO, msg, msg_len);
+
+	/* Re-raise the signal to trigger the core dump */
+	sa_dfl.sa_handler = SIG_DFL;
+	sigaction(sig_num, &sa_dfl, NULL);
+	raise(sig_num);
+}
+
+static int read_stack_limit(void)
+{
+	unsigned long stack_start, stack_end;
+	struct rlimit rlim;
+	char line[256];
+	int ret = 0;
+	FILE *fp;
+
+	if (getrlimit(RLIMIT_STACK, &rlim)) {
+		ERROR_GLIBC("getrlimit");
+		return -1;
+	}
+
+	fp = fopen("/proc/self/maps", "r");
+	if (!fp) {
+		ERROR_GLIBC("fopen");
+		return -1;
+	}
+
+	while (fgets(line, sizeof(line), fp)) {
+		if (strstr(line, "[stack]")) {
+			if (sscanf(line, "%lx-%lx", &stack_start, &stack_end) != 2) {
+				ERROR_GLIBC("sscanf");
+				ret = -1;
+				goto done;
+			}
+			stack_limit = stack_end - rlim.rlim_cur;
+			goto done;
+		}
+	}
+
+	ret = -1;
+	ERROR("/proc/self/maps: can't find [stack]");
+
+done:
+	fclose(fp);
+
+	return ret;
+}
+
+int init_signal_handler(void)
+{
+	int signals[] = {SIGSEGV, SIGBUS, SIGILL, SIGABRT};
+	struct sigaction sa;
+	stack_t ss;
+
+	if (read_stack_limit())
+		return -1;
+
+	ss.ss_sp = malloc(SIGSTKSZ);
+	if (!ss.ss_sp) {
+		ERROR_GLIBC("malloc");
+		return -1;
+	}
+	ss.ss_size = SIGSTKSZ;
+	ss.ss_flags = 0;
+
+	if (sigaltstack(&ss, NULL) == -1) {
+		ERROR_GLIBC("sigaltstack");
+		return -1;
+	}
+
+	sa.sa_sigaction = signal_handler;
+	sigemptyset(&sa.sa_mask);
+
+	sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
+
+	for (int i = 0; i < ARRAY_SIZE(signals); i++) {
+		if (sigaction(signals[i], &sa, NULL) == -1) {
+			ERROR_GLIBC("sigaction");
+			return -1;
+		}
+	}
+
+	return 0;
+}