From: Josh Poimboeuf <jpoimboe@kernel.org>
Date: Fri, 14 Mar 2025 19:29:08 +0000 (-0700)
Subject: objtool: Add --Werror option
X-Git-Tag: io_uring-6.15-20250403~141^2~5
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=bb62243943dbef4592266e817f4e2e5a96293907;p=linux-block.git

objtool: Add --Werror option

Any objtool warning has the potential of reflecting (or triggering) a
major bug in the kernel or compiler which could result in crashing the
kernel or breaking the livepatch consistency model.

In preparation for failing the build on objtool errors/warnings, add a
new --Werror option.

[ jpoimboe: commit log, comments, error out on fatal errors too ]

Co-developed-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/e423ea4ec297f510a108aa6c78b52b9fe30fa8c1.1741975349.git.jpoimboe@kernel.org
---

diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 3de3afa0a19c..c201650efe49 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -101,6 +101,7 @@ 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"),
+	OPT_BOOLEAN(0,   "Werror", &opts.werror, "return error on warnings"),
 
 	OPT_END(),
 };
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 2f64e46fe02d..48d7bc5b4736 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -4756,9 +4756,18 @@ 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.
+	 * CONFIG_OBJTOOL_WERROR upgrades all warnings (and errors) to actual
+	 * errors.
+	 *
+	 * Note that even "fatal" type errors don't actually return an error
+	 * without CONFIG_OBJTOOL_WERROR.  That probably needs improved at some
+	 * point.
 	 */
+	if (opts.werror && (ret || warnings)) {
+		if (warnings)
+			WARN("%d warning(s) upgraded to errors", warnings);
+		return 1;
+	}
+
 	return 0;
 }
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index 25cfa01758b9..b18f114cdaa4 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -39,6 +39,7 @@ struct opts {
 	bool sec_address;
 	bool stats;
 	bool verbose;
+	bool werror;
 };
 
 extern struct opts opts;