linux-kernel - [tip: objtool/core] objtool: Fix "unexpected end of section" warning for alternatives

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Message-ID: <176060837360.709179.3733383336366312679.tip-bot2@tip-bot2>
Date: Thu, 16 Oct 2025 09:52:53 -0000
From: "tip-bot2 for Josh Poimboeuf" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Petr Mladek <pmladek@...e.com>, Joe Lawrence <joe.lawrence@...hat.com>,
 Josh Poimboeuf <jpoimboe@...nel.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: objtool/core] objtool: Fix "unexpected end of section" warning
 for alternatives

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     4cdee7888f42f5573b380ddfa9da43208e759bdc
Gitweb:        https://git.kernel.org/tip/4cdee7888f42f5573b380ddfa9da43208e759bdc
Author:        Josh Poimboeuf <jpoimboe@...nel.org>
AuthorDate:    Wed, 17 Sep 2025 09:03:30 -07:00
Committer:     Josh Poimboeuf <jpoimboe@...nel.org>
CommitterDate: Tue, 14 Oct 2025 14:45:24 -07:00

objtool: Fix "unexpected end of section" warning for alternatives

Due to the short circuiting logic in next_insn_to_validate(), control
flow may silently transition from .altinstr_replacement to .text without
a corresponding nested call to validate_branch().

As a result the validate_branch() 'sec' variable doesn't get
reinitialized, which can trigger a confusing "unexpected end of section"
warning which blames .altinstr_replacement rather than the offending
fallthrough function.

Fix that by not caching the section.  There's no point in doing that
anyway.

Acked-by: Petr Mladek <pmladek@...e.com>
Tested-by: Joe Lawrence <joe.lawrence@...hat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 tools/objtool/check.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 65eb900..c2e46f9 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3512,15 +3512,12 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 {
 	struct alternative *alt;
 	struct instruction *next_insn, *prev_insn = NULL;
-	struct section *sec;
 	u8 visited;
 	int ret;
 
 	if (func && func->ignore)
 		return 0;
 
-	sec = insn->sec;
-
 	while (1) {
 		next_insn = next_insn_to_validate(file, insn);
 
@@ -3760,7 +3757,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 
 			WARN("%s%sunexpected end of section %s",
 			     func ? func->name : "", func ? "(): " : "",
-			     sec->name);
+			     insn->sec->name);
 			return 1;
 		}