All of
 help / color / mirror / Atom feed
From: Nathan Chancellor <>
Cc:,,,,,,,,  Nathan Chancellor <>
Subject: [PATCH] kbuild: Enable -Wincompatible-function-pointer-types-strict in W=1
Date: Mon, 02 Oct 2023 15:19:46 -0700	[thread overview]
Message-ID: <> (raw)

-Wincompatible-function-pointer-types-strict aims to catch clang kernel
Control Flow Integrity (kCFI) violations at build time (rather than run
time) by validating function pointer assignments against the expected
prototype, similar to the existing -Wincompatible-function-pointer-types
that is considered a hard error in the kernel. The -strict variant
requires the types to match exactly, as opposed to just matching in
terms of ABI compatibility. This is primarily visible with int/unsigned
int in lieu of enum types or vice versa.

The tree is not completely clean, so this warning cannot currently be
enabled unconditionally. However, there are only warnings in one
subsystem ('drivers/counter'), so it is really close. In order to
benefit from CI infrastructure that tests with W=1, enable this warning
at that level, so that new instances have a chance of being caught and
fixed during development.

This should eventually be a hard error in a similar manner as
Wincompatible-function-pointer-types but some subsystems test
with W=1 + CONFIG_WERROR=n, so it would be rude to break their builds
when they do not care about warnings outside of their subsystem.

Signed-off-by: Nathan Chancellor <>
 scripts/Makefile.extrawarn | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 2fe6f2828d37..9662f7fd6e39 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -108,6 +108,7 @@ KBUILD_CFLAGS += $(call cc-option, -Wformat-overflow)
 KBUILD_CFLAGS += $(call cc-option, -Wformat-truncation)
 KBUILD_CFLAGS += $(call cc-option, -Wstringop-overflow)
 KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
+KBUILD_CFLAGS += $(call cc-option, -Wincompatible-function-pointer-types-strict)

base-commit: ce9ecca0238b140b88f43859b211c9fdfd8e5b70
change-id: 20231002-enable-wincompatible-function-pointer-types-strict-w-1-4a56b99b8c6f

Best regards,
Nathan Chancellor <>

             reply	other threads:[~2023-10-02 22:19 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-10-02 22:19 Nathan Chancellor [this message]
2023-10-03  5:53 ` [PATCH] kbuild: Enable -Wincompatible-function-pointer-types-strict in W=1 kernel test robot
2023-10-03 18:38   ` Nathan Chancellor
2023-10-05 18:38 ` Nick Desaulniers

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.