From: Nathan Chancellor <natechancellor@gmail.com>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: akpm@linux-foundation.org, mka@chromium.org,
ghackmann@android.com, ghackmann@google.com,
stable@vger.kernel.org, Kees Cook <keescook@chromium.org>,
Ingo Molnar <mingo@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Josh Poimboeuf <jpoimboe@redhat.com>, Wei Wang <wvw@google.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Randy Dunlap <rdunlap@infradead.org>, NeilBrown <neilb@suse.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] kernel.h: Disable -Wreturn-stack-address for _THIS_IP_
Date: Mon, 30 Jul 2018 11:39:43 -0700 [thread overview]
Message-ID: <20180730183943.GA9221@flashbox> (raw)
In-Reply-To: <20180730170622.99349-1-ndesaulniers@google.com>
On Mon, Jul 30, 2018 at 10:06:20AM -0700, Nick Desaulniers wrote:
> Starting with Clang-7.0, _THIS_IP_ generates -Wreturn-stack-address
> warnings for almost every translation unit. In general, I'd prefer to
> leave this on (returning the address of a stack allocated variable is in
> general a bad idea) and disable it only at whitelisted call sites.
>
> We can't do something like:
> #pragma clang diagnostic push
> #pragma clang diagnostic ignored "-Wreturn-stack-address"
> <code>
> #pragma clang diagnostic pop
>
> in a GNU Statement Expression or macro, hence we use _Pragma, which is
> its raison d'être: https://gcc.gnu.org/onlinedocs/cpp/Pragmas.html
>
> Cc: stable@vger.kernel.org # 4.17, 4.14, 4.9, 4.4
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
> include/linux/kernel.h | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 941dc0a5a877..5906f5727f90 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -168,7 +168,15 @@
>
>
> #define _RET_IP_ (unsigned long)__builtin_return_address(0)
> -#define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; })
> +#define _THIS_IP_ ( \
> +{ \
> + _Pragma("clang diagnostic push") \
> + _Pragma("clang diagnostic ignored \"-Wreturn-stack-address\"") \
> + __label__ __here; \
> +__here: (unsigned long)&&__here; \
> + _Pragma("clang diagnostic pop") \
> +} \
> +)
>
> #ifdef CONFIG_LBDAF
> # include <asm/div64.h>
> --
> 2.18.0.233.g985f88cf7e-goog
>
This generates a ton of warnings with GCC:
In file included from ./include/linux/spinlock.h:58,
from ./include/linux/mmzone.h:8,
from ./include/linux/gfp.h:6,
from ./include/linux/slab.h:15,
from ./include/linux/crypto.h:24,
from arch/x86/kernel/asm-offsets.c:9:
./include/linux/bottom_half.h: In function ‘local_bh_disable’:
./include/linux/bottom_half.h:19: error: ignoring #pragma clang diagnostic [-Werror=unknown-pragmas]
__local_bh_disable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
./include/linux/bottom_half.h:19: error: ignoring #pragma clang diagnostic [-Werror=unknown-pragmas]
./include/linux/bottom_half.h:19: error: ignoring #pragma clang diagnostic [-Werror=unknown-pragmas]
./include/linux/bottom_half.h: In function ‘local_bh_enable’:
./include/linux/bottom_half.h:32: error: ignoring #pragma clang diagnostic [-Werror=unknown-pragmas]
__local_bh_enable_ip(_THIS_IP_, SOFTIRQ_DISABLE_OFFSET);
./include/linux/bottom_half.h:32: error: ignoring #pragma clang diagnostic [-Werror=unknown-pragmas]
./include/linux/bottom_half.h:32: error: ignoring #pragma clang diagnostic [-Werror=unknown-pragmas]
cc1: all warnings being treated as errors
make[1]: *** [Kbuild:56: arch/x86/kernel/asm-offsets.s] Error 1
make: *** [Makefile:1081: prepare0] Error 2
A proper solution is probably going to involve what was done for the
-Wattribute-alias warnings from GCC 8 in commits 8793bb7f4a9d ("kbuild:
add macro for controlling warnings to linux/compiler.h") and
bee20031772a ("disable -Wattribute-alias warning for SYSCALL_DEFINEx()")
I'll take a look at it in a bit unless someone beats me to it.
Thanks!
Nathan
next prev parent reply other threads:[~2018-07-30 20:16 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-30 17:06 [PATCH] kernel.h: Disable -Wreturn-stack-address for _THIS_IP_ Nick Desaulniers
2018-07-30 18:39 ` Nathan Chancellor [this message]
2018-07-30 19:48 ` Nick Desaulniers
2018-07-30 20:01 ` Nathan Chancellor
2018-07-30 21:15 ` Nick Desaulniers
2018-07-31 6:50 ` kbuild test robot
2018-07-31 16:46 ` 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:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180730183943.GA9221@flashbox \
--to=natechancellor@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=ghackmann@android.com \
--cc=ghackmann@google.com \
--cc=gregkh@linuxfoundation.org \
--cc=jpoimboe@redhat.com \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=mka@chromium.org \
--cc=ndesaulniers@google.com \
--cc=neilb@suse.com \
--cc=rdunlap@infradead.org \
--cc=stable@vger.kernel.org \
--cc=wvw@google.com \
--cc=yamada.masahiro@socionext.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* 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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).