linux-kernel - [PATCH 8/9] objtool: Collapse annotate sequences

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Message-Id: <20241122121556.447242540@infradead.org>
Date: Fri, 22 Nov 2024 13:10:24 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: jpoimboe@...hat.com
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org
Subject: [PATCH 8/9] objtool: Collapse annotate sequences

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

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/20241111125218.921110073@infradead.org
---
 tools/objtool/check.c |   87 ++++++++++++++++++--------------------------------
 1 file changed, 32 insertions(+), 55 deletions(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2308,21 +2308,24 @@ static int read_annotate(struct objtool_
 	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;
 }
 
@@ -2356,26 +2359,21 @@ static int __annotate_ifc(struct objtool
 	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;
@@ -2384,6 +2382,10 @@ static int __annotate_instr(struct objto
 		insn->instr--;
 		break;
 
+	case ANNOTYPE_UNRET_BEGIN:
+		insn->unret = 1;
+		break;
+
 	default:
 		break;
 	}
@@ -2391,16 +2393,6 @@ static int __annotate_instr(struct objto
 	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.
@@ -2507,14 +2499,7 @@ static int decode_sections(struct objtoo
 	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;
 
@@ -2560,15 +2545,7 @@ static int decode_sections(struct objtoo
 	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;