linux-kernel - Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c

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Date:   Fri, 30 Jun 2017 11:32:54 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     "H. Peter Anvin" <hpa@...or.com>
Cc:     Michael Davidson <md@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c

El Thu, Jun 22, 2017 at 03:37:23PM -0700 H. Peter Anvin ha dit:

> On 06/22/17 15:31, Matthias Kaehlcke wrote:
> > (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@...gle.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;
> 
> Acked-by: H. Peter Anvin <hpa@...or.com>

Ingo, do you plan to pick this change?

Thanks

Matthias