From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Paul Mackerras <paulus@samba.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Kees Cook <keescook@chromium.org>,
Arvind Sankar <nivedita@alum.mit.edu>,
Peter Zijlstra <peterz@infradead.org>,
Alexei Starovoitov <ast@kernel.org>,
Randy Dunlap <rdunlap@infradead.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc: avoid broken GCC __attribute__((optimize))
Date: Wed, 25 Nov 2020 22:57:41 +1100 (AEDT) [thread overview]
Message-ID: <160630540052.2174375.9307119240987760572.b4-ty@ellerman.id.au> (raw)
In-Reply-To: <20201028080433.26799-1-ardb@kernel.org>
On Wed, 28 Oct 2020 09:04:33 +0100, Ard Biesheuvel wrote:
> Commit 7053f80d9696 ("powerpc/64: Prevent stack protection in early boot")
> introduced a couple of uses of __attribute__((optimize)) with function
> scope, to disable the stack protector in some early boot code.
>
> Unfortunately, and this is documented in the GCC man pages [0], overriding
> function attributes for optimization is broken, and is only supported for
> debug scenarios, not for production: the problem appears to be that
> setting GCC -f flags using this method will cause it to forget about some
> or all other optimization settings that have been applied.
>
> [...]
Applied to powerpc/next.
[1/1] powerpc: Avoid broken GCC __attribute__((optimize))
https://git.kernel.org/powerpc/c/a7223f5bfcaeade4a86d35263493bcda6c940891
cheers
WARNING: multiple messages have this Message-ID (diff)
From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: linux-kernel@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>
Cc: Kees Cook <keescook@chromium.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Peter Zijlstra <peterz@infradead.org>,
Randy Dunlap <rdunlap@infradead.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Alexei Starovoitov <ast@kernel.org>,
Arvind Sankar <nivedita@alum.mit.edu>,
Paul Mackerras <paulus@samba.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Thomas Gleixner <tglx@linutronix.de>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc: avoid broken GCC __attribute__((optimize))
Date: Wed, 25 Nov 2020 22:57:41 +1100 (AEDT) [thread overview]
Message-ID: <160630540052.2174375.9307119240987760572.b4-ty@ellerman.id.au> (raw)
In-Reply-To: <20201028080433.26799-1-ardb@kernel.org>
On Wed, 28 Oct 2020 09:04:33 +0100, Ard Biesheuvel wrote:
> Commit 7053f80d9696 ("powerpc/64: Prevent stack protection in early boot")
> introduced a couple of uses of __attribute__((optimize)) with function
> scope, to disable the stack protector in some early boot code.
>
> Unfortunately, and this is documented in the GCC man pages [0], overriding
> function attributes for optimization is broken, and is only supported for
> debug scenarios, not for production: the problem appears to be that
> setting GCC -f flags using this method will cause it to forget about some
> or all other optimization settings that have been applied.
>
> [...]
Applied to powerpc/next.
[1/1] powerpc: Avoid broken GCC __attribute__((optimize))
https://git.kernel.org/powerpc/c/a7223f5bfcaeade4a86d35263493bcda6c940891
cheers
next prev parent reply other threads:[~2020-11-25 11:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-28 8:04 [PATCH] powerpc: avoid broken GCC __attribute__((optimize)) Ard Biesheuvel
2020-10-28 8:04 ` Ard Biesheuvel
2020-10-28 8:19 ` Test Results: " snowpatch
2020-10-28 8:29 ` [PATCH] " Ard Biesheuvel
2020-10-28 8:29 ` Ard Biesheuvel
2020-10-29 11:35 ` Michael Ellerman
2020-10-29 11:35 ` Michael Ellerman
2020-10-28 10:08 ` kernel test robot
2020-11-25 11:57 ` Michael Ellerman [this message]
2020-11-25 11:57 ` Michael Ellerman
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