linux-kernel - [PATCH v2 1/2] objtool: Add --Werror

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Message-ID: <20241218-objtool-strict-v2-1-a5297c961434@google.com>
Date: Wed, 18 Dec 2024 14:58:55 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Josh Poimboeuf <jpoimboe@...nel.org>, Peter Zijlstra <peterz@...radead.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, Masahiro Yamada <masahiroy@...nel.org>, 
	Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nicolas@...sle.eu>
Cc: linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org, 
	Brendan Jackman <jackmanb@...gle.com>
Subject: [PATCH v2 1/2] objtool: Add --Werror

At present objtool only prints to the terminal when observing "fatal
warnings". This option lets you have it produce an error instead.

The use case for this is noinstr validation; so far I've never seen any
false warnings here, but it quite often detects real bugs. It would
be useful for the build to fail when I have those bugs.

Signed-off-by: Brendan Jackman <jackmanb@...gle.com>
---
 tools/objtool/builtin-check.c           | 6 ++++++
 tools/objtool/check.c                   | 7 ++-----
 tools/objtool/include/objtool/builtin.h | 1 +
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 387d56a7f5fb8da8435d0a3f5c05eeee66932c9b..0b28082df90710ff7127327deb857c0548f378c7 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -94,6 +94,12 @@ static const struct option check_options[] = {
 	OPT_BOOLEAN(0, "sec-address", &opts.sec_address, "print section addresses in warnings"),
 	OPT_BOOLEAN(0, "stats", &opts.stats, "print statistics"),
 	OPT_BOOLEAN('v', "verbose", &opts.verbose, "verbose warnings"),
+	/*
+	 *  For now, don't fail the kernel build on fatal warnings by default.
+	 *  These errors are still fairly common due to the growing matrix of
+	 *  supported toolchains and their recent pace of change.
+	 */
+	OPT_BOOLEAN(0, "Werror", &opts.werror, "fail on fatal warnings"),
 
 	OPT_END(),
 };
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 4ce176ad411fb12a10101bbedbb6180275941b4b..7c73517dc11c98cd7163f96dc8f4158389d58428 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4941,10 +4941,7 @@ int check(struct objtool_file *file)
 	}
 
 out:
-	/*
-	 *  For now, don't fail the kernel build on fatal warnings.  These
-	 *  errors are still fairly common due to the growing matrix of
-	 *  supported toolchains and their recent pace of change.
-	 */
+	if (opts.werror && warnings)
+		return 1;
 	return 0;
 }
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index fcca6662c8b4b5e0048e54fada8694cc2e6ebc34..97d668010efadfa05bb6e25e1967a7d72bf77815 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -38,6 +38,7 @@ struct opts {
 	bool sec_address;
 	bool stats;
 	bool verbose;
+	bool werror;
 };
 
 extern struct opts opts;

-- 
2.47.1.613.gc27f4b7a9f-goog