From 2116b349e29a2e9ba17ea2e45b31234e4b350793 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:38:52 +0100
Subject: [PATCH 01/18] objtool: Generic annotation infrastructure

Avoid endless .discard.foo sections for each annotation, create a
single .discard.annotate_insn section that takes an annotation type along
with the instruction.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094310.932794537@infradead.org
---
 include/linux/objtool.h | 18 +++++++++++++++++
 tools/objtool/check.c   | 45 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index b3b8d3dab52d5..d98531ecc6873 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -57,6 +57,13 @@
 	".long 998b\n\t"						\
 	".popsection\n\t"
 
+#define ASM_ANNOTATE(type)						\
+	"911:\n\t"							\
+	".pushsection .discard.annotate_insn,\"M\",@progbits,8\n\t"	\
+	".long 911b - .\n\t"						\
+	".long " __stringify(type) "\n\t"				\
+	".popsection\n\t"
+
 #else /* __ASSEMBLY__ */
 
 /*
@@ -146,6 +153,14 @@
 	.popsection
 .endm
 
+.macro ANNOTATE type:req
+.Lhere_\@:
+	.pushsection .discard.annotate_insn,"M",@progbits,8
+	.long	.Lhere_\@ - .
+	.long	\type
+	.popsection
+.endm
+
 #endif /* __ASSEMBLY__ */
 
 #else /* !CONFIG_OBJTOOL */
@@ -155,6 +170,7 @@
 #define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t"
 #define STACK_FRAME_NON_STANDARD(func)
 #define STACK_FRAME_NON_STANDARD_FP(func)
+#define ASM_ANNOTATE(type)
 #define ANNOTATE_NOENDBR
 #define ASM_REACHABLE
 #else
@@ -167,6 +183,8 @@
 .endm
 .macro REACHABLE
 .endm
+.macro ANNOTATE type:req
+.endm
 #endif
 
 #endif /* CONFIG_OBJTOOL */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4ce176ad411fb..b0efc8ee16d6d 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2373,6 +2373,49 @@ static int read_unwind_hints(struct objtool_file *file)
 	return 0;
 }
 
+static int read_annotate(struct objtool_file *file, void (*func)(int type, struct instruction *insn))
+{
+	struct section *sec;
+	struct instruction *insn;
+	struct reloc *reloc;
+	int type;
+
+	sec = find_section_by_name(file->elf, ".discard.annotate_insn");
+	if (!sec)
+		return 0;
+
+	if (!sec->rsec)
+		return 0;
+
+	if (sec->sh.sh_entsize != 8) {
+		static bool warned = false;
+		if (!warned) {
+			WARN("%s: dodgy linker, sh_entsize != 8", sec->name);
+			warned = true;
+		}
+		sec->sh.sh_entsize = 8;
+	}
+
+	for_each_reloc(sec->rsec, reloc) {
+		type = *(u32 *)(sec->data->d_buf + (reloc_idx(reloc) * sec->sh.sh_entsize) + 4);
+
+		insn = find_insn(file, reloc->sym->sec,
+				 reloc->sym->offset + reloc_addend(reloc));
+		if (!insn) {
+			WARN("bad .discard.annotate_insn entry: %d of type %d", reloc_idx(reloc), type);
+			return -1;
+		}
+
+		func(type, insn);
+	}
+
+	return 0;
+}
+
+static void __annotate_nop(int type, struct instruction *insn)
+{
+}
+
 static int read_noendbr_hints(struct objtool_file *file)
 {
 	struct instruction *insn;
@@ -2670,6 +2713,8 @@ static int decode_sections(struct objtool_file *file)
 	if (ret)
 		return ret;
 
+	read_annotate(file, __annotate_nop);
+
 	/*
 	 * Must be before read_unwind_hints() since that needs insn->noendbr.
 	 */

From 22c3d58079688b697f36d670616e463cbb14d058 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:38:53 +0100
Subject: [PATCH 02/18] objtool: Convert ANNOTATE_NOENDBR to ANNOTATE

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.042140333@infradead.org
---
 include/linux/objtool.h             | 17 ++++-----------
 include/linux/objtool_types.h       |  5 +++++
 tools/include/linux/objtool_types.h |  5 +++++
 tools/objtool/check.c               | 32 +++++------------------------
 4 files changed, 19 insertions(+), 40 deletions(-)

diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index d98531ecc6873..b5e9c0ab4048e 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -45,12 +45,6 @@
 #define STACK_FRAME_NON_STANDARD_FP(func)
 #endif
 
-#define ANNOTATE_NOENDBR					\
-	"986: \n\t"						\
-	".pushsection .discard.noendbr\n\t"			\
-	".long 986b\n\t"					\
-	".popsection\n\t"
-
 #define ASM_REACHABLE							\
 	"998:\n\t"							\
 	".pushsection .discard.reachable\n\t"				\
@@ -64,6 +58,8 @@
 	".long " __stringify(type) "\n\t"				\
 	".popsection\n\t"
 
+#define ANNOTATE_NOENDBR	ASM_ANNOTATE(ANNOTYPE_NOENDBR)
+
 #else /* __ASSEMBLY__ */
 
 /*
@@ -122,13 +118,6 @@
 #endif
 .endm
 
-.macro ANNOTATE_NOENDBR
-.Lhere_\@:
-	.pushsection .discard.noendbr
-	.long	.Lhere_\@
-	.popsection
-.endm
-
 /*
  * Use objtool to validate the entry requirement that all code paths do
  * VALIDATE_UNRET_END before RET.
@@ -161,6 +150,8 @@
 	.popsection
 .endm
 
+#define ANNOTATE_NOENDBR	ANNOTATE type=ANNOTYPE_NOENDBR
+
 #endif /* __ASSEMBLY__ */
 
 #else /* !CONFIG_OBJTOOL */
diff --git a/include/linux/objtool_types.h b/include/linux/objtool_types.h
index 453a4f4ef39d4..4884f8cf84291 100644
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -54,4 +54,9 @@ struct unwind_hint {
 #define UNWIND_HINT_TYPE_SAVE		6
 #define UNWIND_HINT_TYPE_RESTORE	7
 
+/*
+ * Annotate types
+ */
+#define ANNOTYPE_NOENDBR		1
+
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/include/linux/objtool_types.h b/tools/include/linux/objtool_types.h
index 453a4f4ef39d4..4884f8cf84291 100644
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -54,4 +54,9 @@ struct unwind_hint {
 #define UNWIND_HINT_TYPE_SAVE		6
 #define UNWIND_HINT_TYPE_RESTORE	7
 
+/*
+ * Annotate types
+ */
+#define ANNOTYPE_NOENDBR		1
+
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b0efc8ee16d6d..a74ff26860f72 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2412,32 +2412,12 @@ static int read_annotate(struct objtool_file *file, void (*func)(int type, struc
 	return 0;
 }
 
-static void __annotate_nop(int type, struct instruction *insn)
+static void __annotate_noendbr(int type, struct instruction *insn)
 {
-}
-
-static int read_noendbr_hints(struct objtool_file *file)
-{
-	struct instruction *insn;
-	struct section *rsec;
-	struct reloc *reloc;
-
-	rsec = find_section_by_name(file->elf, ".rela.discard.noendbr");
-	if (!rsec)
-		return 0;
-
-	for_each_reloc(rsec, reloc) {
-		insn = find_insn(file, reloc->sym->sec,
-				 reloc->sym->offset + reloc_addend(reloc));
-		if (!insn) {
-			WARN("bad .discard.noendbr entry");
-			return -1;
-		}
-
-		insn->noendbr = 1;
-	}
+	if (type != ANNOTYPE_NOENDBR)
+		return;
 
-	return 0;
+	insn->noendbr = 1;
 }
 
 static int read_retpoline_hints(struct objtool_file *file)
@@ -2713,12 +2693,10 @@ static int decode_sections(struct objtool_file *file)
 	if (ret)
 		return ret;
 
-	read_annotate(file, __annotate_nop);
-
 	/*
 	 * Must be before read_unwind_hints() since that needs insn->noendbr.
 	 */
-	ret = read_noendbr_hints(file);
+	ret = read_annotate(file, __annotate_noendbr);
 	if (ret)
 		return ret;
 

From bf5febebd99fddfc6226a94e937d38a8d470b24e Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:38:54 +0100
Subject: [PATCH 03/18] objtool: Convert ANNOTATE_RETPOLINE_SAFE to ANNOTATE

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.145275669@infradead.org
---
 arch/x86/include/asm/nospec-branch.h | 13 ++-----
 include/linux/objtool_types.h        |  1 +
 tools/include/linux/objtool_types.h  |  1 +
 tools/objtool/check.c                | 52 ++++++++++------------------
 4 files changed, 22 insertions(+), 45 deletions(-)

diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 96b410b1d4e84..50340a125953b 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -184,12 +184,7 @@
  * objtool the subsequent indirect jump/call is vouched safe for retpoline
  * builds.
  */
-.macro ANNOTATE_RETPOLINE_SAFE
-.Lhere_\@:
-	.pushsection .discard.retpoline_safe
-	.long .Lhere_\@
-	.popsection
-.endm
+#define ANNOTATE_RETPOLINE_SAFE	ANNOTATE type=ANNOTYPE_RETPOLINE_SAFE
 
 /*
  * (ab)use RETPOLINE_SAFE on RET to annotate away 'bare' RET instructions
@@ -350,11 +345,7 @@
 
 #else /* __ASSEMBLY__ */
 
-#define ANNOTATE_RETPOLINE_SAFE					\
-	"999:\n\t"						\
-	".pushsection .discard.retpoline_safe\n\t"		\
-	".long 999b\n\t"					\
-	".popsection\n\t"
+#define ANNOTATE_RETPOLINE_SAFE ASM_ANNOTATE(ANNOTYPE_RETPOLINE_SAFE)
 
 typedef u8 retpoline_thunk_t[RETPOLINE_THUNK_SIZE];
 extern retpoline_thunk_t __x86_indirect_thunk_array[];
diff --git a/include/linux/objtool_types.h b/include/linux/objtool_types.h
index 4884f8cf84291..1b348361ad1d7 100644
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -58,5 +58,6 @@ struct unwind_hint {
  * Annotate types
  */
 #define ANNOTYPE_NOENDBR		1
+#define ANNOTYPE_RETPOLINE_SAFE		2
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/include/linux/objtool_types.h b/tools/include/linux/objtool_types.h
index 4884f8cf84291..1b348361ad1d7 100644
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -58,5 +58,6 @@ struct unwind_hint {
  * Annotate types
  */
 #define ANNOTYPE_NOENDBR		1
+#define ANNOTYPE_RETPOLINE_SAFE		2
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index a74ff26860f72..c5b52309b80dc 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2373,12 +2373,12 @@ static int read_unwind_hints(struct objtool_file *file)
 	return 0;
 }
 
-static int read_annotate(struct objtool_file *file, void (*func)(int type, struct instruction *insn))
+static int read_annotate(struct objtool_file *file, int (*func)(int type, struct instruction *insn))
 {
 	struct section *sec;
 	struct instruction *insn;
 	struct reloc *reloc;
-	int type;
+	int type, ret;
 
 	sec = find_section_by_name(file->elf, ".discard.annotate_insn");
 	if (!sec)
@@ -2406,53 +2406,37 @@ static int read_annotate(struct objtool_file *file, void (*func)(int type, struc
 			return -1;
 		}
 
-		func(type, insn);
+		ret = func(type, insn);
+		if (ret < 0)
+			return ret;
 	}
 
 	return 0;
 }
 
-static void __annotate_noendbr(int type, struct instruction *insn)
+static int __annotate_noendbr(int type, struct instruction *insn)
 {
 	if (type != ANNOTYPE_NOENDBR)
-		return;
+		return 0;
 
 	insn->noendbr = 1;
+	return 0;
 }
 
-static int read_retpoline_hints(struct objtool_file *file)
+static int __annotate_retpoline_safe(int type, struct instruction *insn)
 {
-	struct section *rsec;
-	struct instruction *insn;
-	struct reloc *reloc;
-
-	rsec = find_section_by_name(file->elf, ".rela.discard.retpoline_safe");
-	if (!rsec)
+	if (type != ANNOTYPE_RETPOLINE_SAFE)
 		return 0;
 
-	for_each_reloc(rsec, reloc) {
-		if (reloc->sym->type != STT_SECTION) {
-			WARN("unexpected relocation symbol type in %s", rsec->name);
-			return -1;
-		}
-
-		insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
-		if (!insn) {
-			WARN("bad .discard.retpoline_safe entry");
-			return -1;
-		}
-
-		if (insn->type != INSN_JUMP_DYNAMIC &&
-		    insn->type != INSN_CALL_DYNAMIC &&
-		    insn->type != INSN_RETURN &&
-		    insn->type != INSN_NOP) {
-			WARN_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
-			return -1;
-		}
-
-		insn->retpoline_safe = true;
+	if (insn->type != INSN_JUMP_DYNAMIC &&
+	    insn->type != INSN_CALL_DYNAMIC &&
+	    insn->type != INSN_RETURN &&
+	    insn->type != INSN_NOP) {
+		WARN_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
+		return -1;
 	}
 
+	insn->retpoline_safe = true;
 	return 0;
 }
 
@@ -2742,7 +2726,7 @@ static int decode_sections(struct objtool_file *file)
 	if (ret)
 		return ret;
 
-	ret = read_retpoline_hints(file);
+	ret = read_annotate(file, __annotate_retpoline_safe);
 	if (ret)
 		return ret;
 

From 317f2a64618c528539d17fe6957a64106087fbd2 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:38:55 +0100
Subject: [PATCH 04/18] objtool: Convert instrumentation_{begin,end}() to
 ANNOTATE

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.245980207@infradead.org
---
 include/linux/instrumentation.h     | 11 +++----
 include/linux/objtool.h             | 12 +++++--
 include/linux/objtool_types.h       |  2 ++
 tools/include/linux/objtool_types.h |  2 ++
 tools/objtool/check.c               | 49 ++++++-----------------------
 5 files changed, 28 insertions(+), 48 deletions(-)

diff --git a/include/linux/instrumentation.h b/include/linux/instrumentation.h
index bc7babe91b2e6..c8f866cf02d88 100644
--- a/include/linux/instrumentation.h
+++ b/include/linux/instrumentation.h
@@ -4,14 +4,14 @@
 
 #ifdef CONFIG_NOINSTR_VALIDATION
 
+#include <linux/objtool.h>
 #include <linux/stringify.h>
 
 /* Begin/end of an instrumentation safe region */
 #define __instrumentation_begin(c) ({					\
 	asm volatile(__stringify(c) ": nop\n\t"				\
-		     ".pushsection .discard.instr_begin\n\t"		\
-		     ".long " __stringify(c) "b - .\n\t"		\
-		     ".popsection\n\t" : : "i" (c));			\
+		     __ASM_ANNOTATE(__ASM_BREF(c), ANNOTYPE_INSTR_BEGIN)\
+		     : : "i" (c));					\
 })
 #define instrumentation_begin() __instrumentation_begin(__COUNTER__)
 
@@ -48,9 +48,8 @@
  */
 #define __instrumentation_end(c) ({					\
 	asm volatile(__stringify(c) ": nop\n\t"				\
-		     ".pushsection .discard.instr_end\n\t"		\
-		     ".long " __stringify(c) "b - .\n\t"		\
-		     ".popsection\n\t" : : "i" (c));			\
+		     __ASM_ANNOTATE(__ASM_BREF(c), ANNOTYPE_INSTR_END)	\
+		     : : "i" (c));					\
 })
 #define instrumentation_end() __instrumentation_end(__COUNTER__)
 #else /* !CONFIG_NOINSTR_VALIDATION */
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index b5e9c0ab4048e..89c67cd7eebeb 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -51,13 +51,18 @@
 	".long 998b\n\t"						\
 	".popsection\n\t"
 
-#define ASM_ANNOTATE(type)						\
-	"911:\n\t"							\
+#define __ASM_BREF(label)	label ## b
+
+#define __ASM_ANNOTATE(label, type)					\
 	".pushsection .discard.annotate_insn,\"M\",@progbits,8\n\t"	\
-	".long 911b - .\n\t"						\
+	".long " __stringify(label) " - .\n\t"			\
 	".long " __stringify(type) "\n\t"				\
 	".popsection\n\t"
 
+#define ASM_ANNOTATE(type)						\
+	"911:\n\t"						\
+	__ASM_ANNOTATE(911b, type)
+
 #define ANNOTATE_NOENDBR	ASM_ANNOTATE(ANNOTYPE_NOENDBR)
 
 #else /* __ASSEMBLY__ */
@@ -161,6 +166,7 @@
 #define UNWIND_HINT(type, sp_reg, sp_offset, signal) "\n\t"
 #define STACK_FRAME_NON_STANDARD(func)
 #define STACK_FRAME_NON_STANDARD_FP(func)
+#define __ASM_ANNOTATE(label, type)
 #define ASM_ANNOTATE(type)
 #define ANNOTATE_NOENDBR
 #define ASM_REACHABLE
diff --git a/include/linux/objtool_types.h b/include/linux/objtool_types.h
index 1b348361ad1d7..d4d68dd36f7a1 100644
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -59,5 +59,7 @@ struct unwind_hint {
  */
 #define ANNOTYPE_NOENDBR		1
 #define ANNOTYPE_RETPOLINE_SAFE		2
+#define ANNOTYPE_INSTR_BEGIN		3
+#define ANNOTYPE_INSTR_END		4
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/include/linux/objtool_types.h b/tools/include/linux/objtool_types.h
index 1b348361ad1d7..d4d68dd36f7a1 100644
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -59,5 +59,7 @@ struct unwind_hint {
  */
 #define ANNOTYPE_NOENDBR		1
 #define ANNOTYPE_RETPOLINE_SAFE		2
+#define ANNOTYPE_INSTR_BEGIN		3
+#define ANNOTYPE_INSTR_END		4
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c5b52309b80dc..8e39c7f484d80 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2440,48 +2440,19 @@ static int __annotate_retpoline_safe(int type, struct instruction *insn)
 	return 0;
 }
 
-static int read_instr_hints(struct objtool_file *file)
+static int __annotate_instr(int type, struct instruction *insn)
 {
-	struct section *rsec;
-	struct instruction *insn;
-	struct reloc *reloc;
-
-	rsec = find_section_by_name(file->elf, ".rela.discard.instr_end");
-	if (!rsec)
-		return 0;
-
-	for_each_reloc(rsec, reloc) {
-		if (reloc->sym->type != STT_SECTION) {
-			WARN("unexpected relocation symbol type in %s", rsec->name);
-			return -1;
-		}
-
-		insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
-		if (!insn) {
-			WARN("bad .discard.instr_end entry");
-			return -1;
-		}
+	switch (type) {
+	case ANNOTYPE_INSTR_BEGIN:
+		insn->instr++;
+		break;
 
+	case ANNOTYPE_INSTR_END:
 		insn->instr--;
-	}
-
-	rsec = find_section_by_name(file->elf, ".rela.discard.instr_begin");
-	if (!rsec)
-		return 0;
-
-	for_each_reloc(rsec, reloc) {
-		if (reloc->sym->type != STT_SECTION) {
-			WARN("unexpected relocation symbol type in %s", rsec->name);
-			return -1;
-		}
-
-		insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
-		if (!insn) {
-			WARN("bad .discard.instr_begin entry");
-			return -1;
-		}
+		break;
 
-		insn->instr++;
+	default:
+		break;
 	}
 
 	return 0;
@@ -2730,7 +2701,7 @@ static int decode_sections(struct objtool_file *file)
 	if (ret)
 		return ret;
 
-	ret = read_instr_hints(file);
+	ret = read_annotate(file, __annotate_instr);
 	if (ret)
 		return ret;
 

From 18aa6118a1689b4d73c5ebbd917ae3f20c9c0db1 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:38:56 +0100
Subject: [PATCH 05/18] objtool: Convert VALIDATE_UNRET_BEGIN to ANNOTATE

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.358508242@infradead.org
---
 include/linux/objtool.h             |  9 +++------
 include/linux/objtool_types.h       |  1 +
 tools/include/linux/objtool_types.h |  1 +
 tools/objtool/check.c               | 28 +++++-----------------------
 4 files changed, 10 insertions(+), 29 deletions(-)

diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 89c67cd7eebeb..5f0bf8052dc70 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -130,15 +130,12 @@
  * NOTE: The macro must be used at the beginning of a global symbol, otherwise
  * it will be ignored.
  */
-.macro VALIDATE_UNRET_BEGIN
 #if defined(CONFIG_NOINSTR_VALIDATION) && \
 	(defined(CONFIG_MITIGATION_UNRET_ENTRY) || defined(CONFIG_MITIGATION_SRSO))
-.Lhere_\@:
-	.pushsection .discard.validate_unret
-	.long	.Lhere_\@ - .
-	.popsection
+#define VALIDATE_UNRET_BEGIN	ANNOTATE type=ANNOTYPE_UNRET_BEGIN
+#else
+#define VALIDATE_UNRET_BEGIN
 #endif
-.endm
 
 .macro REACHABLE
 .Lhere_\@:
diff --git a/include/linux/objtool_types.h b/include/linux/objtool_types.h
index d4d68dd36f7a1..16236a56364b5 100644
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -61,5 +61,6 @@ struct unwind_hint {
 #define ANNOTYPE_RETPOLINE_SAFE		2
 #define ANNOTYPE_INSTR_BEGIN		3
 #define ANNOTYPE_INSTR_END		4
+#define ANNOTYPE_UNRET_BEGIN		5
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/include/linux/objtool_types.h b/tools/include/linux/objtool_types.h
index d4d68dd36f7a1..16236a56364b5 100644
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -61,5 +61,6 @@ struct unwind_hint {
 #define ANNOTYPE_RETPOLINE_SAFE		2
 #define ANNOTYPE_INSTR_BEGIN		3
 #define ANNOTYPE_INSTR_END		4
+#define ANNOTYPE_UNRET_BEGIN		5
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 8e39c7f484d80..2a703748cad1f 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2458,33 +2458,15 @@ static int __annotate_instr(int type, struct instruction *insn)
 	return 0;
 }
 
-static int read_validate_unret_hints(struct objtool_file *file)
+static int __annotate_unret(int type, struct instruction *insn)
 {
-	struct section *rsec;
-	struct instruction *insn;
-	struct reloc *reloc;
-
-	rsec = find_section_by_name(file->elf, ".rela.discard.validate_unret");
-	if (!rsec)
+	if (type != ANNOTYPE_UNRET_BEGIN)
 		return 0;
 
-	for_each_reloc(rsec, reloc) {
-		if (reloc->sym->type != STT_SECTION) {
-			WARN("unexpected relocation symbol type in %s", rsec->name);
-			return -1;
-		}
-
-		insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
-		if (!insn) {
-			WARN("bad .discard.instr_end entry");
-			return -1;
-		}
-		insn->unret = 1;
-	}
-
+	insn->unret = 1;
 	return 0;
-}
 
+}
 
 static int read_intra_function_calls(struct objtool_file *file)
 {
@@ -2705,7 +2687,7 @@ static int decode_sections(struct objtool_file *file)
 	if (ret)
 		return ret;
 
-	ret = read_validate_unret_hints(file);
+	ret = read_annotate(file, __annotate_unret);
 	if (ret)
 		return ret;
 

From f0cd57c35a75f152d3b31b9be3f7f413b96a6d3f Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:38:57 +0100
Subject: [PATCH 06/18] objtool: Convert ANNOTATE_IGNORE_ALTERNATIVE to
 ANNOTATE

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.465691316@infradead.org
---
 arch/x86/include/asm/alternative.h  | 14 ++-------
 include/linux/objtool_types.h       |  1 +
 tools/include/linux/objtool_types.h |  1 +
 tools/objtool/check.c               | 45 +++++++----------------------
 4 files changed, 15 insertions(+), 46 deletions(-)

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index dc03a647776d9..595695f85f804 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -4,6 +4,7 @@
 
 #include <linux/types.h>
 #include <linux/stringify.h>
+#include <linux/objtool.h>
 #include <asm/asm.h>
 
 #define ALT_FLAGS_SHIFT		16
@@ -58,11 +59,7 @@
  * objtool annotation to ignore the alternatives and only consider the original
  * instruction(s).
  */
-#define ANNOTATE_IGNORE_ALTERNATIVE				\
-	"999:\n\t"						\
-	".pushsection .discard.ignore_alts\n\t"			\
-	".long 999b\n\t"					\
-	".popsection\n\t"
+#define ANNOTATE_IGNORE_ALTERNATIVE	ASM_ANNOTATE(ANNOTYPE_IGNORE_ALTS)
 
 /*
  * The patching flags are part of the upper bits of the @ft_flags parameter when
@@ -314,12 +311,7 @@ void nop_func(void);
  * objtool annotation to ignore the alternatives and only consider the original
  * instruction(s).
  */
-.macro ANNOTATE_IGNORE_ALTERNATIVE
-	.Lannotate_\@:
-	.pushsection .discard.ignore_alts
-	.long .Lannotate_\@
-	.popsection
-.endm
+#define ANNOTATE_IGNORE_ALTERNATIVE ANNOTATE type=ANNOTYPE_IGNORE_ALTS
 
 /*
  * Issue one struct alt_instr descriptor entry (need to put it into
diff --git a/include/linux/objtool_types.h b/include/linux/objtool_types.h
index 16236a56364b5..eab15dbe1cb72 100644
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -62,5 +62,6 @@ struct unwind_hint {
 #define ANNOTYPE_INSTR_BEGIN		3
 #define ANNOTYPE_INSTR_END		4
 #define ANNOTYPE_UNRET_BEGIN		5
+#define ANNOTYPE_IGNORE_ALTS		6
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/include/linux/objtool_types.h b/tools/include/linux/objtool_types.h
index 16236a56364b5..eab15dbe1cb72 100644
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -62,5 +62,6 @@ struct unwind_hint {
 #define ANNOTYPE_INSTR_BEGIN		3
 #define ANNOTYPE_INSTR_END		4
 #define ANNOTYPE_UNRET_BEGIN		5
+#define ANNOTYPE_IGNORE_ALTS		6
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 2a703748cad1f..ba2cb9b693999 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1309,40 +1309,6 @@ static void add_uaccess_safe(struct objtool_file *file)
 	}
 }
 
-/*
- * FIXME: For now, just ignore any alternatives which add retpolines.  This is
- * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
- * But it at least allows objtool to understand the control flow *around* the
- * retpoline.
- */
-static int add_ignore_alternatives(struct objtool_file *file)
-{
-	struct section *rsec;
-	struct reloc *reloc;
-	struct instruction *insn;
-
-	rsec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
-	if (!rsec)
-		return 0;
-
-	for_each_reloc(rsec, reloc) {
-		if (reloc->sym->type != STT_SECTION) {
-			WARN("unexpected relocation symbol type in %s", rsec->name);
-			return -1;
-		}
-
-		insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
-		if (!insn) {
-			WARN("bad .discard.ignore_alts entry");
-			return -1;
-		}
-
-		insn->ignore_alts = true;
-	}
-
-	return 0;
-}
-
 /*
  * Symbols that replace INSN_CALL_DYNAMIC, every (tail) call to such a symbol
  * will be added to the .retpoline_sites section.
@@ -2414,6 +2380,15 @@ static int read_annotate(struct objtool_file *file, int (*func)(int type, struct
 	return 0;
 }
 
+static int __annotate_ignore_alts(int type, struct instruction *insn)
+{
+	if (type != ANNOTYPE_IGNORE_ALTS)
+		return 0;
+
+	insn->ignore_alts = true;
+	return 0;
+}
+
 static int __annotate_noendbr(int type, struct instruction *insn)
 {
 	if (type != ANNOTYPE_NOENDBR)
@@ -2626,7 +2601,7 @@ static int decode_sections(struct objtool_file *file)
 	add_ignores(file);
 	add_uaccess_safe(file);
 
-	ret = add_ignore_alternatives(file);
+	ret = read_annotate(file, __annotate_ignore_alts);
 	if (ret)
 		return ret;
 

From 112765ca1cb9353e71b4f5af4e6e6c4a69c28d99 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:38:58 +0100
Subject: [PATCH 07/18] objtool: Convert ANNOTATE_INTRA_FUNCTION_CALL to
 ANNOTATE

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.584892071@infradead.org
---
 include/linux/objtool.h             | 16 ++---
 include/linux/objtool_types.h       |  1 +
 tools/include/linux/objtool_types.h |  1 +
 tools/objtool/check.c               | 96 ++++++++++++-----------------
 4 files changed, 47 insertions(+), 67 deletions(-)

diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 5f0bf8052dc70..42287c1e32ce0 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -67,16 +67,6 @@
 
 #else /* __ASSEMBLY__ */
 
-/*
- * 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				\
-	999:							\
-	.pushsection .discard.intra_function_calls;		\
-	.long 999b;						\
-	.popsection;
-
 /*
  * In asm, there are two kinds of code: normal C-type callable functions and
  * the rest.  The normal callable functions can be called by other code, and
@@ -154,6 +144,12 @@
 
 #define ANNOTATE_NOENDBR	ANNOTATE type=ANNOTYPE_NOENDBR
 
+/*
+ * 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 ANNOTATE type=ANNOTYPE_INTRA_FUNCTION_CALL
+
 #endif /* __ASSEMBLY__ */
 
 #else /* !CONFIG_OBJTOOL */
diff --git a/include/linux/objtool_types.h b/include/linux/objtool_types.h
index eab15dbe1cb72..23d6fb6d04c70 100644
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -63,5 +63,6 @@ struct unwind_hint {
 #define ANNOTYPE_INSTR_END		4
 #define ANNOTYPE_UNRET_BEGIN		5
 #define ANNOTYPE_IGNORE_ALTS		6
+#define ANNOTYPE_INTRA_FUNCTION_CALL	7
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/include/linux/objtool_types.h b/tools/include/linux/objtool_types.h
index eab15dbe1cb72..23d6fb6d04c70 100644
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -63,5 +63,6 @@ struct unwind_hint {
 #define ANNOTYPE_INSTR_END		4
 #define ANNOTYPE_UNRET_BEGIN		5
 #define ANNOTYPE_IGNORE_ALTS		6
+#define ANNOTYPE_INTRA_FUNCTION_CALL	7
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index ba2cb9b693999..2222fe7108328 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2339,7 +2339,8 @@ static int read_unwind_hints(struct objtool_file *file)
 	return 0;
 }
 
-static int read_annotate(struct objtool_file *file, int (*func)(int type, struct instruction *insn))
+static int read_annotate(struct objtool_file *file,
+			 int (*func)(struct objtool_file *file, int type, struct instruction *insn))
 {
 	struct section *sec;
 	struct instruction *insn;
@@ -2372,7 +2373,7 @@ static int read_annotate(struct objtool_file *file, int (*func)(int type, struct
 			return -1;
 		}
 
-		ret = func(type, insn);
+		ret = func(file, type, insn);
 		if (ret < 0)
 			return ret;
 	}
@@ -2380,7 +2381,7 @@ static int read_annotate(struct objtool_file *file, int (*func)(int type, struct
 	return 0;
 }
 
-static int __annotate_ignore_alts(int type, struct instruction *insn)
+static int __annotate_ignore_alts(struct objtool_file *file, int type, struct instruction *insn)
 {
 	if (type != ANNOTYPE_IGNORE_ALTS)
 		return 0;
@@ -2389,7 +2390,7 @@ static int __annotate_ignore_alts(int type, struct instruction *insn)
 	return 0;
 }
 
-static int __annotate_noendbr(int type, struct instruction *insn)
+static int __annotate_noendbr(struct objtool_file *file, int type, struct instruction *insn)
 {
 	if (type != ANNOTYPE_NOENDBR)
 		return 0;
@@ -2398,7 +2399,37 @@ static int __annotate_noendbr(int type, struct instruction *insn)
 	return 0;
 }
 
-static int __annotate_retpoline_safe(int type, struct instruction *insn)
+static int __annotate_ifc(struct objtool_file *file, int type, struct instruction *insn)
+{
+	unsigned long dest_off;
+
+	if (type != ANNOTYPE_INTRA_FUNCTION_CALL)
+		return 0;
+
+	if (insn->type != INSN_CALL) {
+		WARN_INSN(insn, "intra_function_call not a direct call");
+		return -1;
+	}
+
+	/*
+	 * Treat intra-function CALLs as JMPs, but with a stack_op.
+	 * See add_call_destinations(), which strips stack_ops from
+	 * normal CALLs.
+	 */
+	insn->type = INSN_JUMP_UNCONDITIONAL;
+
+	dest_off = arch_jump_destination(insn);
+	insn->jump_dest = find_insn(file, insn->sec, dest_off);
+	if (!insn->jump_dest) {
+		WARN_INSN(insn, "can't find call dest at %s+0x%lx",
+			  insn->sec->name, dest_off);
+		return -1;
+	}
+
+	return 0;
+}
+
+static int __annotate_retpoline_safe(struct objtool_file *file, int type, struct instruction *insn)
 {
 	if (type != ANNOTYPE_RETPOLINE_SAFE)
 		return 0;
@@ -2415,7 +2446,7 @@ static int __annotate_retpoline_safe(int type, struct instruction *insn)
 	return 0;
 }
 
-static int __annotate_instr(int type, struct instruction *insn)
+static int __annotate_instr(struct objtool_file *file, int type, struct instruction *insn)
 {
 	switch (type) {
 	case ANNOTYPE_INSTR_BEGIN:
@@ -2433,7 +2464,7 @@ static int __annotate_instr(int type, struct instruction *insn)
 	return 0;
 }
 
-static int __annotate_unret(int type, struct instruction *insn)
+static int __annotate_unret(struct objtool_file *file, int type, struct instruction *insn)
 {
 	if (type != ANNOTYPE_UNRET_BEGIN)
 		return 0;
@@ -2443,55 +2474,6 @@ static int __annotate_unret(int type, struct instruction *insn)
 
 }
 
-static int read_intra_function_calls(struct objtool_file *file)
-{
-	struct instruction *insn;
-	struct section *rsec;
-	struct reloc *reloc;
-
-	rsec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls");
-	if (!rsec)
-		return 0;
-
-	for_each_reloc(rsec, reloc) {
-		unsigned long dest_off;
-
-		if (reloc->sym->type != STT_SECTION) {
-			WARN("unexpected relocation symbol type in %s",
-			     rsec->name);
-			return -1;
-		}
-
-		insn = find_insn(file, reloc->sym->sec, reloc_addend(reloc));
-		if (!insn) {
-			WARN("bad .discard.intra_function_call entry");
-			return -1;
-		}
-
-		if (insn->type != INSN_CALL) {
-			WARN_INSN(insn, "intra_function_call not a direct call");
-			return -1;
-		}
-
-		/*
-		 * Treat intra-function CALLs as JMPs, but with a stack_op.
-		 * See add_call_destinations(), which strips stack_ops from
-		 * normal CALLs.
-		 */
-		insn->type = INSN_JUMP_UNCONDITIONAL;
-
-		dest_off = arch_jump_destination(insn);
-		insn->jump_dest = find_insn(file, insn->sec, dest_off);
-		if (!insn->jump_dest) {
-			WARN_INSN(insn, "can't find call dest at %s+0x%lx",
-				  insn->sec->name, dest_off);
-			return -1;
-		}
-	}
-
-	return 0;
-}
-
 /*
  * Return true if name matches an instrumentation function, where calls to that
  * function from noinstr code can safely be removed, but compilers won't do so.
@@ -2630,7 +2612,7 @@ static int decode_sections(struct objtool_file *file)
 	 * Must be before add_call_destination(); it changes INSN_CALL to
 	 * INSN_JUMP.
 	 */
-	ret = read_intra_function_calls(file);
+	ret = read_annotate(file, __annotate_ifc);
 	if (ret)
 		return ret;
 

From a8a330dd9900024dc18b048c4f0f3c6ad22ff4c1 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:38:59 +0100
Subject: [PATCH 08/18] objtool: Collapse annotate sequences

Reduce read_annotate() runs by collapsing subsequent runs into a
single call.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.688871544@infradead.org
---
 tools/objtool/check.c | 87 ++++++++++++++++---------------------------
 1 file changed, 32 insertions(+), 55 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 2222fe7108328..3bea8b2963d34 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2381,21 +2381,24 @@ static int read_annotate(struct objtool_file *file,
 	return 0;
 }
 
-static int __annotate_ignore_alts(struct objtool_file *file, int type, struct instruction *insn)
+static int __annotate_early(struct objtool_file *file, int type, struct instruction *insn)
 {
-	if (type != ANNOTYPE_IGNORE_ALTS)
-		return 0;
+	switch (type) {
+	case ANNOTYPE_IGNORE_ALTS:
+		insn->ignore_alts = true;
+		break;
 
-	insn->ignore_alts = true;
-	return 0;
-}
+	/*
+	 * Must be before read_unwind_hints() since that needs insn->noendbr.
+	 */
+	case ANNOTYPE_NOENDBR:
+		insn->noendbr = 1;
+		break;
 
-static int __annotate_noendbr(struct objtool_file *file, int type, struct instruction *insn)
-{
-	if (type != ANNOTYPE_NOENDBR)
-		return 0;
+	default:
+		break;
+	}
 
-	insn->noendbr = 1;
 	return 0;
 }
 
@@ -2429,26 +2432,21 @@ static int __annotate_ifc(struct objtool_file *file, int type, struct instructio
 	return 0;
 }
 
-static int __annotate_retpoline_safe(struct objtool_file *file, int type, struct instruction *insn)
+static int __annotate_late(struct objtool_file *file, int type, struct instruction *insn)
 {
-	if (type != ANNOTYPE_RETPOLINE_SAFE)
-		return 0;
-
-	if (insn->type != INSN_JUMP_DYNAMIC &&
-	    insn->type != INSN_CALL_DYNAMIC &&
-	    insn->type != INSN_RETURN &&
-	    insn->type != INSN_NOP) {
-		WARN_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
-		return -1;
-	}
+	switch (type) {
+	case ANNOTYPE_RETPOLINE_SAFE:
+		if (insn->type != INSN_JUMP_DYNAMIC &&
+		    insn->type != INSN_CALL_DYNAMIC &&
+		    insn->type != INSN_RETURN &&
+		    insn->type != INSN_NOP) {
+			WARN_INSN(insn, "retpoline_safe hint not an indirect jump/call/ret/nop");
+			return -1;
+		}
 
-	insn->retpoline_safe = true;
-	return 0;
-}
+		insn->retpoline_safe = true;
+		break;
 
-static int __annotate_instr(struct objtool_file *file, int type, struct instruction *insn)
-{
-	switch (type) {
 	case ANNOTYPE_INSTR_BEGIN:
 		insn->instr++;
 		break;
@@ -2457,6 +2455,10 @@ static int __annotate_instr(struct objtool_file *file, int type, struct instruct
 		insn->instr--;
 		break;
 
+	case ANNOTYPE_UNRET_BEGIN:
+		insn->unret = 1;
+		break;
+
 	default:
 		break;
 	}
@@ -2464,16 +2466,6 @@ static int __annotate_instr(struct objtool_file *file, int type, struct instruct
 	return 0;
 }
 
-static int __annotate_unret(struct objtool_file *file, int type, struct instruction *insn)
-{
-	if (type != ANNOTYPE_UNRET_BEGIN)
-		return 0;
-
-	insn->unret = 1;
-	return 0;
-
-}
-
 /*
  * Return true if name matches an instrumentation function, where calls to that
  * function from noinstr code can safely be removed, but compilers won't do so.
@@ -2583,14 +2575,7 @@ static int decode_sections(struct objtool_file *file)
 	add_ignores(file);
 	add_uaccess_safe(file);
 
-	ret = read_annotate(file, __annotate_ignore_alts);
-	if (ret)
-		return ret;
-
-	/*
-	 * Must be before read_unwind_hints() since that needs insn->noendbr.
-	 */
-	ret = read_annotate(file, __annotate_noendbr);
+	ret = read_annotate(file, __annotate_early);
 	if (ret)
 		return ret;
 
@@ -2636,15 +2621,7 @@ static int decode_sections(struct objtool_file *file)
 	if (ret)
 		return ret;
 
-	ret = read_annotate(file, __annotate_retpoline_safe);
-	if (ret)
-		return ret;
-
-	ret = read_annotate(file, __annotate_instr);
-	if (ret)
-		return ret;
-
-	ret = read_annotate(file, __annotate_unret);
+	ret = read_annotate(file, __annotate_late);
 	if (ret)
 		return ret;
 

From bb8170067470cc7af28e4386e600b1e0a6a8956a Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:39:00 +0100
Subject: [PATCH 09/18] objtool: Collect more annotations in objtool.h

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.786598147@infradead.org
---
 arch/x86/include/asm/alternative.h   | 12 -----
 arch/x86/include/asm/nospec-branch.h |  9 ----
 include/linux/instrumentation.h      |  4 +-
 include/linux/objtool.h              | 80 ++++++++++++++++++----------
 4 files changed, 55 insertions(+), 50 deletions(-)

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 595695f85f804..e3903b731305c 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -55,12 +55,6 @@
 #define LOCK_PREFIX ""
 #endif
 
-/*
- * objtool annotation to ignore the alternatives and only consider the original
- * instruction(s).
- */
-#define ANNOTATE_IGNORE_ALTERNATIVE	ASM_ANNOTATE(ANNOTYPE_IGNORE_ALTS)
-
 /*
  * The patching flags are part of the upper bits of the @ft_flags parameter when
  * specifying them. The split is currently like this:
@@ -307,12 +301,6 @@ void nop_func(void);
 	.endm
 #endif
 
-/*
- * objtool annotation to ignore the alternatives and only consider the original
- * instruction(s).
- */
-#define ANNOTATE_IGNORE_ALTERNATIVE ANNOTATE type=ANNOTYPE_IGNORE_ALTS
-
 /*
  * Issue one struct alt_instr descriptor entry (need to put it into
  * the section .altinstructions, see below). This entry contains
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 50340a125953b..7e8bf78c03d5d 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -179,13 +179,6 @@
 
 #ifdef __ASSEMBLY__
 
-/*
- * 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	ANNOTATE type=ANNOTYPE_RETPOLINE_SAFE
-
 /*
  * (ab)use RETPOLINE_SAFE on RET to annotate away 'bare' RET instructions
  * vs RETBleed validation.
@@ -345,8 +338,6 @@
 
 #else /* __ASSEMBLY__ */
 
-#define ANNOTATE_RETPOLINE_SAFE ASM_ANNOTATE(ANNOTYPE_RETPOLINE_SAFE)
-
 typedef u8 retpoline_thunk_t[RETPOLINE_THUNK_SIZE];
 extern retpoline_thunk_t __x86_indirect_thunk_array[];
 extern retpoline_thunk_t __x86_indirect_call_thunk_array[];
diff --git a/include/linux/instrumentation.h b/include/linux/instrumentation.h
index c8f866cf02d88..bf675a8aef8ab 100644
--- a/include/linux/instrumentation.h
+++ b/include/linux/instrumentation.h
@@ -10,7 +10,7 @@
 /* Begin/end of an instrumentation safe region */
 #define __instrumentation_begin(c) ({					\
 	asm volatile(__stringify(c) ": nop\n\t"				\
-		     __ASM_ANNOTATE(__ASM_BREF(c), ANNOTYPE_INSTR_BEGIN)\
+		     ANNOTATE_INSTR_BEGIN(__ASM_BREF(c))		\
 		     : : "i" (c));					\
 })
 #define instrumentation_begin() __instrumentation_begin(__COUNTER__)
@@ -48,7 +48,7 @@
  */
 #define __instrumentation_end(c) ({					\
 	asm volatile(__stringify(c) ": nop\n\t"				\
-		     __ASM_ANNOTATE(__ASM_BREF(c), ANNOTYPE_INSTR_END)	\
+		     ANNOTATE_INSTR_END(__ASM_BREF(c))			\
 		     : : "i" (c));					\
 })
 #define instrumentation_end() __instrumentation_end(__COUNTER__)
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 42287c1e32ce0..fd487d466bb2e 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -63,8 +63,6 @@
 	"911:\n\t"						\
 	__ASM_ANNOTATE(911b, type)
 
-#define ANNOTATE_NOENDBR	ASM_ANNOTATE(ANNOTYPE_NOENDBR)
-
 #else /* __ASSEMBLY__ */
 
 /*
@@ -113,19 +111,6 @@
 #endif
 .endm
 
-/*
- * 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.
- */
-#if defined(CONFIG_NOINSTR_VALIDATION) && \
-	(defined(CONFIG_MITIGATION_UNRET_ENTRY) || defined(CONFIG_MITIGATION_SRSO))
-#define VALIDATE_UNRET_BEGIN	ANNOTATE type=ANNOTYPE_UNRET_BEGIN
-#else
-#define VALIDATE_UNRET_BEGIN
-#endif
 
 .macro REACHABLE
 .Lhere_\@:
@@ -142,14 +127,6 @@
 	.popsection
 .endm
 
-#define ANNOTATE_NOENDBR	ANNOTATE type=ANNOTYPE_NOENDBR
-
-/*
- * 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 ANNOTATE type=ANNOTYPE_INTRA_FUNCTION_CALL
-
 #endif /* __ASSEMBLY__ */
 
 #else /* !CONFIG_OBJTOOL */
@@ -161,16 +138,12 @@
 #define STACK_FRAME_NON_STANDARD_FP(func)
 #define __ASM_ANNOTATE(label, type)
 #define ASM_ANNOTATE(type)
-#define ANNOTATE_NOENDBR
 #define ASM_REACHABLE
 #else
-#define ANNOTATE_INTRA_FUNCTION_CALL
 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
 .endm
 .macro STACK_FRAME_NON_STANDARD func:req
 .endm
-.macro ANNOTATE_NOENDBR
-.endm
 .macro REACHABLE
 .endm
 .macro ANNOTATE type:req
@@ -179,4 +152,57 @@
 
 #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)
+/*
+ * 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, ANNOTYPE_INSTR_BEGIN)
+#define ANNOTATE_INSTR_END(label)	__ASM_ANNOTATE(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)
+
+#else
+#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
+#endif
+
+#if defined(CONFIG_NOINSTR_VALIDATION) && \
+	(defined(CONFIG_MITIGATION_UNRET_ENTRY) || defined(CONFIG_MITIGATION_SRSO))
+#define VALIDATE_UNRET_BEGIN	ANNOTATE_UNRET_BEGIN
+#else
+#define VALIDATE_UNRET_BEGIN
+#endif
+
 #endif /* _LINUX_OBJTOOL_H */

From c837de3810982cd41cd70e5170da1931439f025c Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:39:01 +0100
Subject: [PATCH 10/18] unreachable: Unify

Since barrier_before_unreachable() is empty for !GCC it is trivial to
unify the two definitions. Less is more.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094311.924381359@infradead.org
---
 include/linux/compiler-gcc.h | 12 ------------
 include/linux/compiler.h     | 10 +++++++---
 2 files changed, 7 insertions(+), 15 deletions(-)

diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index d0ed9583743fc..c9b58188ec61e 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -52,18 +52,6 @@
  */
 #define barrier_before_unreachable() asm volatile("")
 
-/*
- * Mark a position in code as unreachable.  This can be used to
- * suppress control flow warnings after asm blocks that transfer
- * control elsewhere.
- */
-#define unreachable() \
-	do {					\
-		annotate_unreachable();		\
-		barrier_before_unreachable();	\
-		__builtin_unreachable();	\
-	} while (0)
-
 #if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP)
 #define __HAVE_BUILTIN_BSWAP32__
 #define __HAVE_BUILTIN_BSWAP64__
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 469a64dd6495f..7be80897a62f7 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -141,12 +141,16 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 #define __annotate_jump_table
 #endif /* CONFIG_OBJTOOL */
 
-#ifndef unreachable
-# define unreachable() do {		\
+/*
+ * Mark a position in code as unreachable.  This can be used to
+ * suppress control flow warnings after asm blocks that transfer
+ * control elsewhere.
+ */
+#define unreachable() do {		\
 	annotate_unreachable();		\
+	barrier_before_unreachable();	\
 	__builtin_unreachable();	\
 } while (0)
-#endif
 
 /*
  * KENTRY - kernel entry point

From 2190966fbc14ca2cd4ea76eefeb96a47d8e390df Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:39:02 +0100
Subject: [PATCH 11/18] x86: Convert unreachable() to BUG()

Avoid unreachable() as it can (and will in the absence of UBSAN)
generate fallthrough code. Use BUG() so we get a UD2 trap (with
unreachable annotation).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.028316261@infradead.org
---
 arch/x86/kernel/process.c | 2 +-
 arch/x86/kernel/reboot.c  | 2 +-
 arch/x86/kvm/svm/sev.c    | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index f63f8fd00a91f..15507e739c255 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -838,7 +838,7 @@ void __noreturn stop_this_cpu(void *dummy)
 #ifdef CONFIG_SMP
 	if (smp_ops.stop_this_cpu) {
 		smp_ops.stop_this_cpu();
-		unreachable();
+		BUG();
 	}
 #endif
 
diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 615922838c510..dc1dd3f3e67fc 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -883,7 +883,7 @@ static int crash_nmi_callback(unsigned int val, struct pt_regs *regs)
 
 	if (smp_ops.stop_this_cpu) {
 		smp_ops.stop_this_cpu();
-		unreachable();
+		BUG();
 	}
 
 	/* Assume hlt works */
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 943bd074a5d37..fe6cc763fd518 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3820,7 +3820,7 @@ static int snp_begin_psc(struct vcpu_svm *svm, struct psc_buffer *psc)
 		goto next_range;
 	}
 
-	unreachable();
+	BUG();
 }
 
 static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)

From 624bde3465f660e54a7cd4c1efc3e536349fead5 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:39:03 +0100
Subject: [PATCH 12/18] loongarch: Use ASM_REACHABLE

annotate_reachable() is unreliable since the compiler is free to place
random code inbetween two consecutive asm() statements.

This removes the last and only annotate_reachable() user.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.133437051@infradead.org
---
 arch/loongarch/include/asm/bug.h | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/asm/bug.h
index 08388876ade4c..561ac1bf79e26 100644
--- a/arch/loongarch/include/asm/bug.h
+++ b/arch/loongarch/include/asm/bug.h
@@ -4,6 +4,7 @@
 
 #include <asm/break.h>
 #include <linux/stringify.h>
+#include <linux/objtool.h>
 
 #ifndef CONFIG_DEBUG_BUGVERBOSE
 #define _BUGVERBOSE_LOCATION(file, line)
@@ -33,25 +34,25 @@
 
 #define ASM_BUG_FLAGS(flags)					\
 	__BUG_ENTRY(flags)					\
-	break		BRK_BUG
+	break		BRK_BUG;
 
 #define ASM_BUG()	ASM_BUG_FLAGS(0)
 
-#define __BUG_FLAGS(flags)					\
-	asm_inline volatile (__stringify(ASM_BUG_FLAGS(flags)));
+#define __BUG_FLAGS(flags, extra)					\
+	asm_inline volatile (__stringify(ASM_BUG_FLAGS(flags))		\
+			     extra);
 
 #define __WARN_FLAGS(flags)					\
 do {								\
 	instrumentation_begin();				\
-	__BUG_FLAGS(BUGFLAG_WARNING|(flags));			\
-	annotate_reachable();					\
+	__BUG_FLAGS(BUGFLAG_WARNING|(flags), ASM_REACHABLE);	\
 	instrumentation_end();					\
 } while (0)
 
 #define BUG()							\
 do {								\
 	instrumentation_begin();				\
-	__BUG_FLAGS(0);						\
+	__BUG_FLAGS(0, "");					\
 	unreachable();						\
 } while (0)
 

From 06e24745985c8dd0da18337503afcf2f2fdbdff1 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:39:04 +0100
Subject: [PATCH 13/18] objtool: Remove annotate_{,un}reachable()

There are no users of annotate_reachable() left.

And the annotate_unreachable() usage in unreachable() is plain wrong;
it will hide dangerous fall-through code-gen.

Remove both.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.235637588@infradead.org
---
 include/linux/compiler.h | 27 -------------------------
 tools/objtool/check.c    | 43 ++--------------------------------------
 2 files changed, 2 insertions(+), 68 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 7be80897a62f7..3d9a0e483e512 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -109,35 +109,9 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 
 /* Unreachable code */
 #ifdef CONFIG_OBJTOOL
-/*
- * These macros help objtool understand GCC code flow for unreachable code.
- * The __COUNTER__ based labels are a hack to make each instance of the macros
- * unique, to convince GCC not to merge duplicate inline asm statements.
- */
-#define __stringify_label(n) #n
-
-#define __annotate_reachable(c) ({					\
-	asm volatile(__stringify_label(c) ":\n\t"			\
-			".pushsection .discard.reachable\n\t"		\
-			".long " __stringify_label(c) "b - .\n\t"	\
-			".popsection\n\t");				\
-})
-#define annotate_reachable() __annotate_reachable(__COUNTER__)
-
-#define __annotate_unreachable(c) ({					\
-	asm volatile(__stringify_label(c) ":\n\t"			\
-		     ".pushsection .discard.unreachable\n\t"		\
-		     ".long " __stringify_label(c) "b - .\n\t"		\
-		     ".popsection\n\t" : : "i" (c));			\
-})
-#define annotate_unreachable() __annotate_unreachable(__COUNTER__)
-
 /* Annotate a C jump table to allow objtool to follow the code flow */
 #define __annotate_jump_table __section(".rodata..c_jump_table,\"a\",@progbits #")
-
 #else /* !CONFIG_OBJTOOL */
-#define annotate_reachable()
-#define annotate_unreachable()
 #define __annotate_jump_table
 #endif /* CONFIG_OBJTOOL */
 
@@ -147,7 +121,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
  * control elsewhere.
  */
 #define unreachable() do {		\
-	annotate_unreachable();		\
 	barrier_before_unreachable();	\
 	__builtin_unreachable();	\
 } while (0)
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 3bea8b2963d34..798cff5bffc42 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -638,47 +638,8 @@ static int add_dead_ends(struct objtool_file *file)
 	uint64_t offset;
 
 	/*
-	 * Check for manually annotated dead ends.
-	 */
-	rsec = find_section_by_name(file->elf, ".rela.discard.unreachable");
-	if (!rsec)
-		goto reachable;
-
-	for_each_reloc(rsec, reloc) {
-		if (reloc->sym->type == STT_SECTION) {
-			offset = reloc_addend(reloc);
-		} else if (reloc->sym->local_label) {
-			offset = reloc->sym->offset;
-		} else {
-			WARN("unexpected relocation symbol type in %s", rsec->name);
-			return -1;
-		}
-
-		insn = find_insn(file, reloc->sym->sec, offset);
-		if (insn)
-			insn = prev_insn_same_sec(file, insn);
-		else if (offset == reloc->sym->sec->sh.sh_size) {
-			insn = find_last_insn(file, reloc->sym->sec);
-			if (!insn) {
-				WARN("can't find unreachable insn at %s+0x%" PRIx64,
-				     reloc->sym->sec->name, offset);
-				return -1;
-			}
-		} else {
-			WARN("can't find unreachable insn at %s+0x%" PRIx64,
-			     reloc->sym->sec->name, offset);
-			return -1;
-		}
-
-		insn->dead_end = true;
-	}
-
-reachable:
-	/*
-	 * These manually annotated reachable checks are needed for GCC 4.4,
-	 * where the Linux unreachable() macro isn't supported.  In that case
-	 * GCC doesn't know the "ud2" is fatal, so it generates code as if it's
-	 * not a dead end.
+	 * UD2 defaults to being a dead-end, allow them to be annotated for
+	 * non-fatal, eg WARN.
 	 */
 	rsec = find_section_by_name(file->elf, ".rela.discard.reachable");
 	if (!rsec)

From e7a174fb43d24adca066e82d1cb9fdee092d48d1 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:39:05 +0100
Subject: [PATCH 14/18] objtool: Convert {.UN}REACHABLE to ANNOTATE

Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.353431347@infradead.org
---
 arch/loongarch/include/asm/bug.h    |  2 +-
 arch/x86/entry/entry_64.S           |  4 +-
 arch/x86/include/asm/bug.h          |  2 +-
 arch/x86/include/asm/irq_stack.h    |  2 +-
 include/linux/objtool.h             | 18 +++----
 include/linux/objtool_types.h       |  1 +
 tools/include/linux/objtool_types.h |  1 +
 tools/objtool/check.c               | 82 ++++++++---------------------
 8 files changed, 36 insertions(+), 76 deletions(-)

diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/asm/bug.h
index 561ac1bf79e26..e25404a938822 100644
--- a/arch/loongarch/include/asm/bug.h
+++ b/arch/loongarch/include/asm/bug.h
@@ -45,7 +45,7 @@
 #define __WARN_FLAGS(flags)					\
 do {								\
 	instrumentation_begin();				\
-	__BUG_FLAGS(BUGFLAG_WARNING|(flags), ASM_REACHABLE);	\
+	__BUG_FLAGS(BUGFLAG_WARNING|(flags), ANNOTATE_REACHABLE);\
 	instrumentation_end();					\
 } while (0)
 
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1b5be07f86698..9248660ad4096 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -311,7 +311,7 @@ SYM_CODE_END(xen_error_entry)
 	call	\cfunc
 
 	/* For some configurations \cfunc ends up being a noreturn. */
-	REACHABLE
+	ANNOTATE_REACHABLE
 
 	jmp	error_return
 .endm
@@ -532,7 +532,7 @@ SYM_CODE_START(\asmsym)
 	call	\cfunc
 
 	/* For some configurations \cfunc ends up being a noreturn. */
-	REACHABLE
+	ANNOTATE_REACHABLE
 
 	jmp	paranoid_exit
 
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index 806649c7f23dc..dd8fb1779d972 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -92,7 +92,7 @@ do {								\
 do {								\
 	__auto_type __flags = BUGFLAG_WARNING|(flags);		\
 	instrumentation_begin();				\
-	_BUG_FLAGS(ASM_UD2, __flags, ASM_REACHABLE);		\
+	_BUG_FLAGS(ASM_UD2, __flags, ANNOTATE_REACHABLE);	\
 	instrumentation_end();					\
 } while (0)
 
diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h
index b71ad173f8776..5455747ed918e 100644
--- a/arch/x86/include/asm/irq_stack.h
+++ b/arch/x86/include/asm/irq_stack.h
@@ -101,7 +101,7 @@
 
 #define ASM_CALL_ARG0							\
 	"call %c[__func]				\n"		\
-	ASM_REACHABLE
+	ANNOTATE_REACHABLE
 
 #define ASM_CALL_ARG1							\
 	"movq	%[arg1], %%rdi				\n"		\
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index fd487d466bb2e..e3cb13583fba2 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -111,14 +111,6 @@
 #endif
 .endm
 
-
-.macro REACHABLE
-.Lhere_\@:
-	.pushsection .discard.reachable
-	.long	.Lhere_\@
-	.popsection
-.endm
-
 .macro ANNOTATE type:req
 .Lhere_\@:
 	.pushsection .discard.annotate_insn,"M",@progbits,8
@@ -138,14 +130,11 @@
 #define STACK_FRAME_NON_STANDARD_FP(func)
 #define __ASM_ANNOTATE(label, type)
 #define ASM_ANNOTATE(type)
-#define ASM_REACHABLE
 #else
 .macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 signal=0
 .endm
 .macro STACK_FRAME_NON_STANDARD func:req
 .endm
-.macro REACHABLE
-.endm
 .macro ANNOTATE type:req
 .endm
 #endif
@@ -187,6 +176,12 @@
  * it will be ignored.
  */
 #define ANNOTATE_UNRET_BEGIN		ASM_ANNOTATE(ANNOTYPE_UNRET_BEGIN)
+/*
+ * This should be used directly after 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		ASM_ANNOTATE(ANNOTYPE_REACHABLE)
 
 #else
 #define ANNOTATE_NOENDBR		ANNOTATE type=ANNOTYPE_NOENDBR
@@ -196,6 +191,7 @@
 #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
 #endif
 
 #if defined(CONFIG_NOINSTR_VALIDATION) && \
diff --git a/include/linux/objtool_types.h b/include/linux/objtool_types.h
index 23d6fb6d04c70..df5d9fa84dba3 100644
--- a/include/linux/objtool_types.h
+++ b/include/linux/objtool_types.h
@@ -64,5 +64,6 @@ struct unwind_hint {
 #define ANNOTYPE_UNRET_BEGIN		5
 #define ANNOTYPE_IGNORE_ALTS		6
 #define ANNOTYPE_INTRA_FUNCTION_CALL	7
+#define ANNOTYPE_REACHABLE		8
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/include/linux/objtool_types.h b/tools/include/linux/objtool_types.h
index 23d6fb6d04c70..df5d9fa84dba3 100644
--- a/tools/include/linux/objtool_types.h
+++ b/tools/include/linux/objtool_types.h
@@ -64,5 +64,6 @@ struct unwind_hint {
 #define ANNOTYPE_UNRET_BEGIN		5
 #define ANNOTYPE_IGNORE_ALTS		6
 #define ANNOTYPE_INTRA_FUNCTION_CALL	7
+#define ANNOTYPE_REACHABLE		8
 
 #endif /* _LINUX_OBJTOOL_TYPES_H */
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 798cff5bffc42..27d0c41535829 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -627,56 +627,6 @@ static struct instruction *find_last_insn(struct objtool_file *file,
 	return insn;
 }
 
-/*
- * Mark "ud2" instructions and manually annotated dead ends.
- */
-static int add_dead_ends(struct objtool_file *file)
-{
-	struct section *rsec;
-	struct reloc *reloc;
-	struct instruction *insn;
-	uint64_t offset;
-
-	/*
-	 * UD2 defaults to being a dead-end, allow them to be annotated for
-	 * non-fatal, eg WARN.
-	 */
-	rsec = find_section_by_name(file->elf, ".rela.discard.reachable");
-	if (!rsec)
-		return 0;
-
-	for_each_reloc(rsec, reloc) {
-		if (reloc->sym->type == STT_SECTION) {
-			offset = reloc_addend(reloc);
-		} else if (reloc->sym->local_label) {
-			offset = reloc->sym->offset;
-		} else {
-			WARN("unexpected relocation symbol type in %s", rsec->name);
-			return -1;
-		}
-
-		insn = find_insn(file, reloc->sym->sec, offset);
-		if (insn)
-			insn = prev_insn_same_sec(file, insn);
-		else if (offset == reloc->sym->sec->sh.sh_size) {
-			insn = find_last_insn(file, reloc->sym->sec);
-			if (!insn) {
-				WARN("can't find reachable insn at %s+0x%" PRIx64,
-				     reloc->sym->sec->name, offset);
-				return -1;
-			}
-		} else {
-			WARN("can't find reachable insn at %s+0x%" PRIx64,
-			     reloc->sym->sec->name, offset);
-			return -1;
-		}
-
-		insn->dead_end = false;
-	}
-
-	return 0;
-}
-
 static int create_static_call_sections(struct objtool_file *file)
 {
 	struct static_call_site *site;
@@ -2306,6 +2256,7 @@ static int read_annotate(struct objtool_file *file,
 	struct section *sec;
 	struct instruction *insn;
 	struct reloc *reloc;
+	uint64_t offset;
 	int type, ret;
 
 	sec = find_section_by_name(file->elf, ".discard.annotate_insn");
@@ -2327,8 +2278,19 @@ 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);
 
-		insn = find_insn(file, reloc->sym->sec,
-				 reloc->sym->offset + reloc_addend(reloc));
+		offset = reloc->sym->offset + reloc_addend(reloc);
+		insn = find_insn(file, reloc->sym->sec, offset);
+
+		/*
+		 * Reachable annotations are 'funneh' and act on the previous instruction :/
+		 */
+		if (type == ANNOTYPE_REACHABLE) {
+			if (insn)
+				insn = prev_insn_same_sec(file, insn);
+			else if (offset == reloc->sym->sec->sh.sh_size)
+				insn = find_last_insn(file, reloc->sym->sec);
+		}
+
 		if (!insn) {
 			WARN("bad .discard.annotate_insn entry: %d of type %d", reloc_idx(reloc), type);
 			return -1;
@@ -2420,6 +2382,10 @@ static int __annotate_late(struct objtool_file *file, int type, struct instructi
 		insn->unret = 1;
 		break;
 
+	case ANNOTYPE_REACHABLE:
+		insn->dead_end = false;
+		break;
+
 	default:
 		break;
 	}
@@ -2566,14 +2532,6 @@ static int decode_sections(struct objtool_file *file)
 	if (ret)
 		return ret;
 
-	/*
-	 * Must be after add_call_destinations() such that it can override
-	 * dead_end_function() marks.
-	 */
-	ret = add_dead_ends(file);
-	if (ret)
-		return ret;
-
 	ret = add_jump_table_alts(file);
 	if (ret)
 		return ret;
@@ -2582,6 +2540,10 @@ static int decode_sections(struct objtool_file *file)
 	if (ret)
 		return ret;
 
+	/*
+	 * 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;

From 87116ae6da034242baf06e799f9f0e2a8ee6a796 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:39:06 +0100
Subject: [PATCH 15/18] objtool: Fix ANNOTATE_REACHABLE to be a normal
 annotation

Currently REACHABLE is weird for being on the instruction after the
instruction it modifies.

Since all REACHABLE annotations have an explicit instruction, flip
them around.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.494176035@infradead.org
---
 arch/loongarch/include/asm/bug.h |  2 +-
 arch/x86/entry/entry_64.S        |  5 ++---
 arch/x86/include/asm/bug.h       |  2 +-
 arch/x86/include/asm/irq_stack.h |  4 ++--
 include/linux/objtool.h          |  4 ++--
 tools/objtool/check.c            | 23 -----------------------
 6 files changed, 8 insertions(+), 32 deletions(-)

diff --git a/arch/loongarch/include/asm/bug.h b/arch/loongarch/include/asm/bug.h
index e25404a938822..f6f254f2c5db5 100644
--- a/arch/loongarch/include/asm/bug.h
+++ b/arch/loongarch/include/asm/bug.h
@@ -45,7 +45,7 @@
 #define __WARN_FLAGS(flags)					\
 do {								\
 	instrumentation_begin();				\
-	__BUG_FLAGS(BUGFLAG_WARNING|(flags), ANNOTATE_REACHABLE);\
+	__BUG_FLAGS(BUGFLAG_WARNING|(flags), ANNOTATE_REACHABLE(10001b));\
 	instrumentation_end();					\
 } while (0)
 
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 9248660ad4096..f52dbe0ad93cd 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -308,10 +308,9 @@ SYM_CODE_END(xen_error_entry)
 		movq	$-1, ORIG_RAX(%rsp)	/* no syscall to restart */
 	.endif
 
-	call	\cfunc
-
 	/* For some configurations \cfunc ends up being a noreturn. */
 	ANNOTATE_REACHABLE
+	call	\cfunc
 
 	jmp	error_return
 .endm
@@ -529,10 +528,10 @@ SYM_CODE_START(\asmsym)
 	movq	%rsp, %rdi		/* pt_regs pointer into first argument */
 	movq	ORIG_RAX(%rsp), %rsi	/* get error code into 2nd argument*/
 	movq	$-1, ORIG_RAX(%rsp)	/* no syscall to restart */
-	call	\cfunc
 
 	/* For some configurations \cfunc ends up being a noreturn. */
 	ANNOTATE_REACHABLE
+	call	\cfunc
 
 	jmp	paranoid_exit
 
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index dd8fb1779d972..e85ac0c7c039e 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -92,7 +92,7 @@ do {								\
 do {								\
 	__auto_type __flags = BUGFLAG_WARNING|(flags);		\
 	instrumentation_begin();				\
-	_BUG_FLAGS(ASM_UD2, __flags, ANNOTATE_REACHABLE);	\
+	_BUG_FLAGS(ASM_UD2, __flags, ANNOTATE_REACHABLE(1b));	\
 	instrumentation_end();					\
 } while (0)
 
diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h
index 5455747ed918e..562a547c29a5b 100644
--- a/arch/x86/include/asm/irq_stack.h
+++ b/arch/x86/include/asm/irq_stack.h
@@ -100,8 +100,8 @@
 }
 
 #define ASM_CALL_ARG0							\
-	"call %c[__func]				\n"		\
-	ANNOTATE_REACHABLE
+	"1: call %c[__func]				\n"		\
+	ANNOTATE_REACHABLE(1b)
 
 #define ASM_CALL_ARG1							\
 	"movq	%[arg1], %%rdi				\n"		\
diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index e3cb13583fba2..c722a921165ba 100644
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -177,11 +177,11 @@
  */
 #define ANNOTATE_UNRET_BEGIN		ASM_ANNOTATE(ANNOTYPE_UNRET_BEGIN)
 /*
- * This should be used directly after an instruction that is considered
+ * 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		ASM_ANNOTATE(ANNOTYPE_REACHABLE)
+#define ANNOTATE_REACHABLE(label)	__ASM_ANNOTATE(label, ANNOTYPE_REACHABLE)
 
 #else
 #define ANNOTATE_NOENDBR		ANNOTATE type=ANNOTYPE_NOENDBR
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 27d0c41535829..26bdd3ebf5d2b 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -614,19 +614,6 @@ static int init_pv_ops(struct objtool_file *file)
 	return 0;
 }
 
-static struct instruction *find_last_insn(struct objtool_file *file,
-					  struct section *sec)
-{
-	struct instruction *insn = NULL;
-	unsigned int offset;
-	unsigned int end = (sec->sh.sh_size > 10) ? sec->sh.sh_size - 10 : 0;
-
-	for (offset = sec->sh.sh_size - 1; offset >= end && !insn; offset--)
-		insn = find_insn(file, sec, offset);
-
-	return insn;
-}
-
 static int create_static_call_sections(struct objtool_file *file)
 {
 	struct static_call_site *site;
@@ -2281,16 +2268,6 @@ static int read_annotate(struct objtool_file *file,
 		offset = reloc->sym->offset + reloc_addend(reloc);
 		insn = find_insn(file, reloc->sym->sec, offset);
 
-		/*
-		 * Reachable annotations are 'funneh' and act on the previous instruction :/
-		 */
-		if (type == ANNOTYPE_REACHABLE) {
-			if (insn)
-				insn = prev_insn_same_sec(file, insn);
-			else if (offset == reloc->sym->sec->sh.sh_size)
-				insn = find_last_insn(file, reloc->sym->sec);
-		}
-
 		if (!insn) {
 			WARN("bad .discard.annotate_insn entry: %d of type %d", reloc_idx(reloc), type);
 			return -1;

From e7e0eb53c2f0f68fe2577472ce2802a4efd9d7ce Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 28 Nov 2024 10:39:07 +0100
Subject: [PATCH 16/18] objtool: Warn about unknown annotation types

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20241128094312.611961175@infradead.org
---
 tools/objtool/check.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 26bdd3ebf5d2b..bfb407f3ac968 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2335,6 +2335,10 @@ static int __annotate_ifc(struct objtool_file *file, int type, struct instructio
 static int __annotate_late(struct objtool_file *file, int type, struct instruction *insn)
 {
 	switch (type) {
+	case ANNOTYPE_NOENDBR:
+		/* early */
+		break;
+
 	case ANNOTYPE_RETPOLINE_SAFE:
 		if (insn->type != INSN_JUMP_DYNAMIC &&
 		    insn->type != INSN_CALL_DYNAMIC &&
@@ -2359,11 +2363,20 @@ static int __annotate_late(struct objtool_file *file, int type, struct instructi
 		insn->unret = 1;
 		break;
 
+	case ANNOTYPE_IGNORE_ALTS:
+		/* early */
+		break;
+
+	case ANNOTYPE_INTRA_FUNCTION_CALL:
+		/* ifc */
+		break;
+
 	case ANNOTYPE_REACHABLE:
 		insn->dead_end = false;
 		break;
 
 	default:
+		WARN_INSN(insn, "Unknown annotation type: %d", type);
 		break;
 	}
 

From c3cb6c158c64dc39838208d51dcd06d1990b371d Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ardb@kernel.org>
Date: Fri, 11 Oct 2024 19:08:50 +0200
Subject: [PATCH 17/18] objtool: Allow arch code to discover jump table size

In preparation for adding support for annotated jump tables, where
ELF relocations and symbols are used to describe the locations of jump
tables in the executable, refactor the jump table discovery logic so the
table size can be returned from arch_find_switch_table().

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20241011170847.334429-12-ardb+git@google.com
---
 tools/objtool/arch/loongarch/special.c  |  3 ++-
 tools/objtool/arch/powerpc/special.c    |  3 ++-
 tools/objtool/arch/x86/special.c        |  4 +++-
 tools/objtool/check.c                   | 31 ++++++++++++++++---------
 tools/objtool/include/objtool/check.h   |  5 +++-
 tools/objtool/include/objtool/special.h |  3 ++-
 6 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/tools/objtool/arch/loongarch/special.c b/tools/objtool/arch/loongarch/special.c
index 9bba1e9318e0b..87230ed570fd0 100644
--- a/tools/objtool/arch/loongarch/special.c
+++ b/tools/objtool/arch/loongarch/special.c
@@ -9,7 +9,8 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
 }
 
 struct reloc *arch_find_switch_table(struct objtool_file *file,
-				     struct instruction *insn)
+				     struct instruction *insn,
+				     unsigned long *table_size)
 {
 	return NULL;
 }
diff --git a/tools/objtool/arch/powerpc/special.c b/tools/objtool/arch/powerpc/special.c
index d33868147196a..51610689abf72 100644
--- a/tools/objtool/arch/powerpc/special.c
+++ b/tools/objtool/arch/powerpc/special.c
@@ -13,7 +13,8 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
 }
 
 struct reloc *arch_find_switch_table(struct objtool_file *file,
-				    struct instruction *insn)
+				     struct instruction *insn,
+				     unsigned long *table_size)
 {
 	exit(-1);
 }
diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c
index 4ea0f9815fda4..9c1c9df09aaa4 100644
--- a/tools/objtool/arch/x86/special.c
+++ b/tools/objtool/arch/x86/special.c
@@ -109,7 +109,8 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
  *    NOTE: MITIGATION_RETPOLINE made it harder still to decode dynamic jumps.
  */
 struct reloc *arch_find_switch_table(struct objtool_file *file,
-				    struct instruction *insn)
+				     struct instruction *insn,
+				     unsigned long *table_size)
 {
 	struct reloc  *text_reloc, *rodata_reloc;
 	struct section *table_sec;
@@ -158,5 +159,6 @@ struct reloc *arch_find_switch_table(struct objtool_file *file,
 	if (reloc_type(text_reloc) == R_X86_64_PC32)
 		file->ignore_unreachables = true;
 
+	*table_size = 0;
 	return rodata_reloc;
 }
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index bfb407f3ac968..e92c5564d9ca8 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -150,6 +150,15 @@ static inline struct reloc *insn_jump_table(struct instruction *insn)
 	return NULL;
 }
 
+static inline unsigned long insn_jump_table_size(struct instruction *insn)
+{
+	if (insn->type == INSN_JUMP_DYNAMIC ||
+	    insn->type == INSN_CALL_DYNAMIC)
+		return insn->_jump_table_size;
+
+	return 0;
+}
+
 static bool is_jump_table_jump(struct instruction *insn)
 {
 	struct alt_group *alt_group = insn->alt_group;
@@ -1937,6 +1946,7 @@ static int add_special_section_alts(struct objtool_file *file)
 static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 			  struct reloc *next_table)
 {
+	unsigned long table_size = insn_jump_table_size(insn);
 	struct symbol *pfunc = insn_func(insn)->pfunc;
 	struct reloc *table = insn_jump_table(insn);
 	struct instruction *dest_insn;
@@ -1951,6 +1961,8 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
 	for_each_reloc_from(table->sec, reloc) {
 
 		/* Check for the end of the table: */
+		if (table_size && reloc_offset(reloc) - reloc_offset(table) >= table_size)
+			break;
 		if (reloc != table && reloc == next_table)
 			break;
 
@@ -1995,12 +2007,12 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
  * find_jump_table() - Given a dynamic jump, find the switch jump table
  * associated with it.
  */
-static struct reloc *find_jump_table(struct objtool_file *file,
-				      struct symbol *func,
-				      struct instruction *insn)
+static void find_jump_table(struct objtool_file *file, struct symbol *func,
+			    struct instruction *insn)
 {
 	struct reloc *table_reloc;
 	struct instruction *dest_insn, *orig_insn = insn;
+	unsigned long table_size;
 
 	/*
 	 * Backward search using the @first_jump_src links, these help avoid
@@ -2021,17 +2033,17 @@ static struct reloc *find_jump_table(struct objtool_file *file,
 		     insn->jump_dest->offset > orig_insn->offset))
 		    break;
 
-		table_reloc = arch_find_switch_table(file, insn);
+		table_reloc = arch_find_switch_table(file, insn, &table_size);
 		if (!table_reloc)
 			continue;
 		dest_insn = find_insn(file, table_reloc->sym->sec, reloc_addend(table_reloc));
 		if (!dest_insn || !insn_func(dest_insn) || insn_func(dest_insn)->pfunc != func)
 			continue;
 
-		return table_reloc;
+		orig_insn->_jump_table = table_reloc;
+		orig_insn->_jump_table_size = table_size;
+		break;
 	}
-
-	return NULL;
 }
 
 /*
@@ -2042,7 +2054,6 @@ static void mark_func_jump_tables(struct objtool_file *file,
 				    struct symbol *func)
 {
 	struct instruction *insn, *last = NULL;
-	struct reloc *reloc;
 
 	func_for_each_insn(file, func, insn) {
 		if (!last)
@@ -2065,9 +2076,7 @@ static void mark_func_jump_tables(struct objtool_file *file,
 		if (insn->type != INSN_JUMP_DYNAMIC)
 			continue;
 
-		reloc = find_jump_table(file, func, insn);
-		if (reloc)
-			insn->_jump_table = reloc;
+		find_jump_table(file, func, insn);
 	}
 }
 
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index daa46f1f0965a..e1cd13cd28a37 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -71,7 +71,10 @@ struct instruction {
 	struct instruction *first_jump_src;
 	union {
 		struct symbol *_call_dest;
-		struct reloc *_jump_table;
+		struct {
+			struct reloc *_jump_table;
+			unsigned long _jump_table_size;
+		};
 	};
 	struct alternative *alts;
 	struct symbol *sym;
diff --git a/tools/objtool/include/objtool/special.h b/tools/objtool/include/objtool/special.h
index 86d4af9c5aa9d..e7ee7ffccefd4 100644
--- a/tools/objtool/include/objtool/special.h
+++ b/tools/objtool/include/objtool/special.h
@@ -38,5 +38,6 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
 				 struct instruction *insn,
 				 struct reloc *reloc);
 struct reloc *arch_find_switch_table(struct objtool_file *file,
-				    struct instruction *insn);
+				     struct instruction *insn,
+				     unsigned long *table_size);
 #endif /* _SPECIAL_H */

From 41a1e976623eb430f7b5a8619d3810b44e6235ad Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 16 Dec 2024 11:08:12 +0100
Subject: [PATCH 18/18] x86/mm: Convert unreachable() to BUG()

Commit 2190966fbc14 ("x86: Convert unreachable() to BUG()") missed
one.

And after commit 06e24745985c ("objtool: Remove
annotate_{,un}reachable()") the invalid use of unreachable()
(rightfully) triggers warnings:

  vmlinux.o: warning: objtool: page_fault_oops() falls through to next function is_prefetch()

Fixes: 2190966fbc14 ("x86: Convert unreachable() to BUG()")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20241216093215.GD12338@noisy.programming.kicks-ass.net
---
 arch/x86/mm/fault.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index e6c469b323ccb..ac52255fab01f 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -678,7 +678,7 @@ page_fault_oops(struct pt_regs *regs, unsigned long error_code,
 			      ASM_CALL_ARG3,
 			      , [arg1] "r" (regs), [arg2] "r" (address), [arg3] "r" (&info));
 
-		unreachable();
+		BUG();
 	}
 #endif