linux-kernel - [PATCH 2/9] objtool: Convert ANNOTATE

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Message-Id: <20241122121555.727837221@infradead.org>
Date: Fri, 22 Nov 2024 13:10:18 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: jpoimboe@...hat.com
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org
Subject: [PATCH 2/9] objtool: Convert ANNOTATE_NOENDBR to ANNOTATE


Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.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(-)

--- 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(x) "\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 */
--- 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 */
--- 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 */
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2412,32 +2412,12 @@ static int read_annotate(struct objtool_
 	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;
+	if (type != ANNOTYPE_NOENDBR)
+		return;
 
-	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;
-	}
-
-	return 0;
+	insn->noendbr = 1;
 }
 
 static int read_retpoline_hints(struct objtool_file *file)
@@ -2713,12 +2693,10 @@ static int decode_sections(struct objtoo
 	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;