linux-kernel - [PATCH] x86: Alias memset to __builtin

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Message-Id: <20200324140639.70079-1-courbet@google.com>
Date:   Tue, 24 Mar 2020 15:06:38 +0100
From:   Clement Courbet <courbet@...gle.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Nathan Chancellor <natechancellor@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Clement Courbet <courbet@...gle.com>,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: [PATCH]     x86: Alias memset to __builtin_memset.

Thanks for the comments. Answers below.

> This ifdef is unnecessary
> This needs to be within #ifndef CONFIG_FORTIFY_SOURCE

Thanks, fixed.

> shouldn't this just be done universally ?

It looks like every architecture does its own magic with memory
functions. I'm not very familiar with how the linux kernel is
organized, do you have a pointer for where this would go if enabled
globally ?

> Who's adding it for 64b?
> Any idea where it's coming from in your
> build? Maybe a local modification to be removed?

Actually this is from our local build configuration. Apparently this
is needed to build on some architectures that redefine common
symbols, but the authors seemed to feel strongly that this should be
on for all architectures. I've reached out to the authors for an
extended rationale.
On the other hand I think that there is no reason to prevent people
from building with freestanding if we can easily allow them to.