From f69e63756f7822fcdad8a34f9967e8b243e883ee Mon Sep 17 00:00:00 2001
From: "Dr. David Alan Gilbert" <linux@treblig.org>
Date: Wed, 2 Oct 2024 18:31:47 +0100
Subject: [PATCH 01/16] printf: Remove unused 'bprintf'

bprintf() is unused. Remove it. It was added in the commit 4370aa4aa753
("vsprintf: add binary printf") but as far as I can see was never used,
unlike the other two functions in that patch.

Link: https://lore.kernel.org/20241002173147.210107-1-linux@treblig.org
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Acked-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 include/linux/string.h |  1 -
 lib/vsprintf.c         | 23 -----------------------
 2 files changed, 24 deletions(-)

diff --git a/include/linux/string.h b/include/linux/string.h
index 0dd27afcfaf7..493ac4862c77 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -335,7 +335,6 @@ int __sysfs_match_string(const char * const *array, size_t n, const char *s);
 #ifdef CONFIG_BINARY_PRINTF
 int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args);
 int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf);
-int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...) __printf(3, 4);
 #endif
 
 extern ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 6ac02bbb7df1..9d3dac38a3f4 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -3428,29 +3428,6 @@ out:
 }
 EXPORT_SYMBOL_GPL(bstr_printf);
 
-/**
- * bprintf - Parse a format string and place args' binary value in a buffer
- * @bin_buf: The buffer to place args' binary value
- * @size: The size of the buffer(by words(32bits), not characters)
- * @fmt: The format string to use
- * @...: Arguments for the format string
- *
- * The function returns the number of words(u32) written
- * into @bin_buf.
- */
-int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...)
-{
-	va_list args;
-	int ret;
-
-	va_start(args, fmt);
-	ret = vbin_printf(bin_buf, size, fmt, args);
-	va_end(args);
-
-	return ret;
-}
-EXPORT_SYMBOL_GPL(bprintf);
-
 #endif /* CONFIG_BINARY_PRINTF */
 
 /**
-- 
2.50.1


From 9022ed0e7e65734d83a0648648589b9fbea8e8c9 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sun, 1 Dec 2024 09:23:33 -0800
Subject: [PATCH 02/16] strscpy: write destination buffer only once

The point behind strscpy() was to once and for all avoid all the
problems with 'strncpy()' and later broken "fixed" versions like
strlcpy() that just made things worse.

So strscpy not only guarantees NUL-termination (unlike strncpy), it also
doesn't do unnecessary padding at the destination.  But at the same time
also avoids byte-at-a-time reads and writes by _allowing_ some extra NUL
writes - within the size, of course - so that the whole copy can be done
with word operations.

It is also stable in the face of a mutable source string: it explicitly
does not read the source buffer multiple times (so an implementation
using "strnlen()+memcpy()" would be wrong), and does not read the source
buffer past the size (like the mis-design that is strlcpy does).

Finally, the return value is designed to be simple and unambiguous: if
the string cannot be copied fully, it returns an actual negative error,
making error handling clearer and simpler (and the caller already knows
the size of the buffer).  Otherwise it returns the string length of the
result.

However, there was one final stability issue that can be important to
callers: the stability of the destination buffer.

In particular, the same way we shouldn't read the source buffer more
than once, we should avoid doing multiple writes to the destination
buffer: first writing a potentially non-terminated string, and then
terminating it with NUL at the end does not result in a stable result
buffer.

Yes, it gives the right result in the end, but if the rule for the
destination buffer was that it is _always_ NUL-terminated even when
accessed concurrently with updates, the final byte of the buffer needs
to always _stay_ as a NUL byte.

[ Note that "final byte is NUL" here is literally about the final byte
  in the destination array, not the terminating NUL at the end of the
  string itself. There is no attempt to try to make concurrent reads and
  writes give any kind of consistent string length or contents, but we
  do want to guarantee that there is always at least that final
  terminating NUL character at the end of the destination array if it
  existed before ]

This is relevant in the kernel for the tsk->comm[] array, for example.
Even without locking (for either readers or writers), we want to know
that while the buffer contents may be garbled, it is always a valid C
string and always has a NUL character at 'comm[TASK_COMM_LEN-1]' (and
never has any "out of thin air" data).

So avoid any "copy possibly non-terminated string, and terminate later"
behavior, and write the destination buffer only once.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 lib/string.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/lib/string.c b/lib/string.c
index 76327b51e36f..eb4486ed40d2 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -104,6 +104,12 @@ char *strncpy(char *dest, const char *src, size_t count)
 EXPORT_SYMBOL(strncpy);
 #endif
 
+#ifdef __BIG_ENDIAN
+# define ALLBUTLAST_BYTE_MASK (~255ul)
+#else
+# define ALLBUTLAST_BYTE_MASK (~0ul >> 8)
+#endif
+
 ssize_t sized_strscpy(char *dest, const char *src, size_t count)
 {
 	const struct word_at_a_time constants = WORD_AT_A_TIME_CONSTANTS;
@@ -147,13 +153,18 @@ ssize_t sized_strscpy(char *dest, const char *src, size_t count)
 			*(unsigned long *)(dest+res) = c & zero_bytemask(data);
 			return res + find_zero(data);
 		}
+		count -= sizeof(unsigned long);
+		if (unlikely(!count)) {
+			c &= ALLBUTLAST_BYTE_MASK;
+			*(unsigned long *)(dest+res) = c;
+			return -E2BIG;
+		}
 		*(unsigned long *)(dest+res) = c;
 		res += sizeof(unsigned long);
-		count -= sizeof(unsigned long);
 		max -= sizeof(unsigned long);
 	}
 
-	while (count) {
+	while (count > 1) {
 		char c;
 
 		c = src[res];
@@ -164,11 +175,11 @@ ssize_t sized_strscpy(char *dest, const char *src, size_t count)
 		count--;
 	}
 
-	/* Hit buffer length without finding a NUL; force NUL-termination. */
-	if (res)
-		dest[res-1] = '\0';
+	/* Force NUL-termination. */
+	dest[res] = '\0';
 
-	return -E2BIG;
+	/* Return E2BIG if the source didn't stop */
+	return src[res] ? -E2BIG : res;
 }
 EXPORT_SYMBOL(sized_strscpy);
 
-- 
2.50.1


From 40384c840ea1944d7c5a392e8975ed088ecf0b37 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sun, 1 Dec 2024 14:28:56 -0800
Subject: [PATCH 03/16] Linux 6.13-rc1

---
 Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Makefile b/Makefile
index e34a97473fb6..93ab62cef244 100644
--- a/Makefile
+++ b/Makefile
@@ -1,8 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 VERSION = 6
-PATCHLEVEL = 12
+PATCHLEVEL = 13
 SUBLEVEL = 0
-EXTRAVERSION =
+EXTRAVERSION = -rc1
 NAME = Baby Opossum Posse
 
 # *DOCUMENTATION*
-- 
2.50.1


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 04/16] 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 b3b8d3dab52d..d98531ecc687 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 4ce176ad411f..b0efc8ee16d6 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.
 	 */
-- 
2.50.1


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 05/16] 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 d98531ecc687..b5e9c0ab4048 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 453a4f4ef39d..4884f8cf8429 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 453a4f4ef39d..4884f8cf8429 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 b0efc8ee16d6..a74ff26860f7 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;
 
-- 
2.50.1


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 06/16] 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 96b410b1d4e8..50340a125953 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 4884f8cf8429..1b348361ad1d 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 4884f8cf8429..1b348361ad1d 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 a74ff26860f7..c5b52309b80d 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;
 
-- 
2.50.1


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 07/16] 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 bc7babe91b2e..c8f866cf02d8 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 b5e9c0ab4048..89c67cd7eebe 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 1b348361ad1d..d4d68dd36f7a 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 1b348361ad1d..d4d68dd36f7a 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 c5b52309b80d..8e39c7f484d8 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;
 
-- 
2.50.1


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 08/16] 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 89c67cd7eebe..5f0bf8052dc7 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 d4d68dd36f7a..16236a56364b 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 d4d68dd36f7a..16236a56364b 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 8e39c7f484d8..2a703748cad1 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;
 
-- 
2.50.1


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 09/16] 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 dc03a647776d..595695f85f80 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 16236a56364b..eab15dbe1cb7 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 16236a56364b..eab15dbe1cb7 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 2a703748cad1..ba2cb9b69399 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;
 
-- 
2.50.1


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 10/16] 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 5f0bf8052dc7..42287c1e32ce 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 eab15dbe1cb7..23d6fb6d04c7 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 eab15dbe1cb7..23d6fb6d04c7 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 ba2cb9b69399..2222fe710832 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;
 
-- 
2.50.1


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 11/16] 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 2222fe710832..3bea8b2963d3 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;
 
-- 
2.50.1


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 12/16] 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 595695f85f80..e3903b731305 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 50340a125953..7e8bf78c03d5 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 c8f866cf02d8..bf675a8aef8a 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 42287c1e32ce..fd487d466bb2 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 */
-- 
2.50.1


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 13/16] 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 d0ed9583743f..c9b58188ec61 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 469a64dd6495..7be80897a62f 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
-- 
2.50.1


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 14/16] 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 f63f8fd00a91..15507e739c25 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 615922838c51..dc1dd3f3e67f 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 943bd074a5d3..fe6cc763fd51 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3820,7 +3820,7 @@ next_range:
 		goto next_range;
 	}
 
-	unreachable();
+	BUG();
 }
 
 static int __sev_snp_update_protected_guest_state(struct kvm_vcpu *vcpu)
-- 
2.50.1


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 15/16] 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 08388876ade4..561ac1bf79e2 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)
 
-- 
2.50.1


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 16/16] 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 7be80897a62f..3d9a0e483e51 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 3bea8b2963d3..798cff5bffc4 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)
-- 
2.50.1