linux-kernel - [tip: objtool/urgent] objtool: Fix function fallthrough detection for vmlinux

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Message-ID: <165039891044.4207.14725257477811071935.tip-bot2@tip-bot2>
Date:   Tue, 19 Apr 2022 20:08:30 -0000
From:   "tip-bot2 for Josh Poimboeuf" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: objtool/urgent] objtool: Fix function fallthrough detection for vmlinux

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

Commit-ID:     08feafe8d1958febf3a9733a3d1564d8fc23340e
Gitweb:        https://git.kernel.org/tip/08feafe8d1958febf3a9733a3d1564d8fc23340e
Author:        Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate:    Mon, 11 Apr 2022 16:10:32 -07:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 19 Apr 2022 21:58:53 +02:00

objtool: Fix function fallthrough detection for vmlinux

Objtool's function fallthrough detection only works on C objects.
The distinction between C and assembly objects no longer makes sense
with objtool running on vmlinux.o.

Now that copy_user_64.S has been fixed up, and an objtool sibling call
detection bug has been fixed, the asm code is in "compliance" and this
hack is no longer needed.  Remove it.

Fixes: ed53a0d97192 ("x86/alternative: Use .ibt_endbr_seal to seal indirect calls")
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/b434cff98eca3a60dcc64c620d7d5d405a0f441c.1649718562.git.jpoimboe@redhat.com
---
 tools/objtool/check.c                   | 2 +-
 tools/objtool/include/objtool/objtool.h | 2 +-
 tools/objtool/objtool.c                 | 1 -
 3 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 0f5d3de..5f10653 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -3310,7 +3310,7 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
 	while (1) {
 		next_insn = next_insn_to_validate(file, insn);
 
-		if (file->c_file && func && insn->func && func != insn->func->pfunc) {
+		if (func && insn->func && func != insn->func->pfunc) {
 			WARN("%s() falls through to next function %s()",
 			     func->name, insn->func->name);
 			return 1;
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index 7a5c13a..a6e72d9 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -27,7 +27,7 @@ struct objtool_file {
 	struct list_head static_call_list;
 	struct list_head mcount_loc_list;
 	struct list_head endbr_list;
-	bool ignore_unreachables, c_file, hints, rodata;
+	bool ignore_unreachables, hints, rodata;
 
 	unsigned int nr_endbr;
 	unsigned int nr_endbr_int;
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index b09946f..843ff3c 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -129,7 +129,6 @@ struct objtool_file *objtool_open_read(const char *_objname)
 	INIT_LIST_HEAD(&file.static_call_list);
 	INIT_LIST_HEAD(&file.mcount_loc_list);
 	INIT_LIST_HEAD(&file.endbr_list);
-	file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
 	file.ignore_unreachables = no_unreachable;
 	file.hints = false;