Date: Thu, 22 Jun 2017 15:31:13 -0700
From: Matthias Kaehlcke <mka@chromium.org>
To: Michael Davidson <md@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c
Message-ID: <20170622223113.GD52338@google.com>
References: <20170317001520.85223-1-md@google.com>
 <20170317001520.85223-5-md@google.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20170317001520.85223-5-md@google.com>
User-Agent: Mutt/1.5.21 (2010-09-15)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1261
Lines: 41

(removed some non-x86 lists and folks from recipients)

El Thu, Mar 16, 2017 at 05:15:17PM -0700 Michael Davidson ha dit:

> undef memcpy and friends in boot/string.c so that the functions
> defined here will have the correct names, otherwise we end up
> up trying to redefine __builtin_memcpy etc.
> Surprisingly, gcc allows this (and, helpfully, discards the
> __builtin_ prefix from the function name when compiling it),
> but clang does not.
> 
> Adding these #undef's appears to preserve what I assume was
> the original intent of the code.

Any comments on this patch?

> Signed-off-by: Michael Davidson <md@google.com>
> ---
>  arch/x86/boot/string.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/x86/boot/string.c b/arch/x86/boot/string.c
> index 5457b02fc050..b40266850869 100644
> --- a/arch/x86/boot/string.c
> +++ b/arch/x86/boot/string.c
> @@ -16,6 +16,15 @@
>  #include "ctype.h"
>  #include "string.h"
>  
> +/*
> + * Undef these macros so that the functions that we provide
> + * here will have the correct names regardless of how string.h
> + * may have chosen to #define them.
> + */
> +#undef memcpy
> +#undef memset
> +#undef memcmp
> +
>  int memcmp(const void *s1, const void *s2, size_t len)
>  {
>  	bool diff;