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From: "H. Peter Anvin" <hpa@zytor.com>
To: Matthias Kaehlcke <mka@chromium.org>, Michael Davidson <md@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.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
Date: Thu, 22 Jun 2017 15:37:23 -0700	[thread overview]
Message-ID: <76723246-ebb4-9bc3-ecc6-e649deb3280f@zytor.com> (raw)
In-Reply-To: <20170622223113.GD52338@google.com>

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@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;

Acked-by: H. Peter Anvin <hpa@zytor.com>

	-hpa

  reply	other threads:[~2017-06-22 22:44 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-17  0:15 [PATCH 0/7] LLVM: make x86_64 kernel build with clang Michael Davidson
2017-03-17  0:15 ` [PATCH 1/7] Makefile, LLVM: add -no-integrated-as to KBUILD_[AC]FLAGS Michael Davidson
2017-04-03 22:49   ` Matthias Kaehlcke
2017-04-21  7:49   ` Masahiro Yamada
2017-04-21  7:49     ` Masahiro Yamada
2017-03-17  0:15 ` [PATCH 2/7] Makefile, x86, LLVM: disable unsupported optimization flags Michael Davidson
2017-03-17 21:32   ` H. Peter Anvin
2017-03-17 21:34     ` H. Peter Anvin
2017-04-05 18:08   ` Masahiro Yamada
2017-04-05 19:01     ` Matthias Kaehlcke
2017-04-05 19:11       ` Michael Davidson
2017-04-10 14:54         ` Masahiro Yamada
2017-03-17  0:15 ` [PATCH 3/7] x86, LLVM: suppress clang warnings about unaligned accesses Michael Davidson
2017-03-17 23:50   ` hpa
2017-04-03 23:01     ` Matthias Kaehlcke
2017-04-13 23:14       ` Matthias Kaehlcke
2017-04-13 23:55         ` H. Peter Anvin
2017-04-14  0:23           ` Matthias Kaehlcke
2017-04-14  5:30             ` hpa
2017-03-17  0:15 ` [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c Michael Davidson
2017-06-22 22:31   ` Matthias Kaehlcke
2017-06-22 22:37     ` H. Peter Anvin [this message]
2017-06-30 18:32       ` Matthias Kaehlcke
2017-03-17  0:15 ` [PATCH 5/7] x86, boot, LLVM: Use regparm=0 for memcpy and memset Michael Davidson
2017-03-17 12:08   ` Peter Zijlstra
2017-06-22 22:38     ` H. Peter Anvin
2017-03-17  0:15 ` [PATCH 6/7] md/raid10, LLVM: get rid of variable length array Michael Davidson
2017-03-17 12:08   ` Peter Zijlstra
2017-03-17 12:31     ` Alexander Potapenko
2017-03-17 12:32       ` Alexander Potapenko
2017-03-17 18:03         ` Borislav Petkov
2017-03-17 18:47           ` Dmitry Vyukov
2017-03-17 18:57             ` Borislav Petkov
2017-03-17 19:05               ` Dmitry Vyukov
2017-03-17 19:26                 ` Peter Zijlstra
2017-03-17 19:26                   ` Peter Zijlstra
2017-03-17 19:29                   ` Peter Zijlstra
2017-03-24 13:50                     ` Dmitry Vyukov
2017-03-24 14:10                       ` Peter Zijlstra
2017-03-24 14:22                         ` Dmitry Vyukov
2017-03-18  0:41                 ` Fengguang Wu
2017-03-17 12:44       ` Peter Zijlstra
2017-03-17 18:52         ` Michael Davidson
2017-03-17 19:27           ` Peter Zijlstra
2017-03-17 20:04             ` hpa
2017-03-24 13:47               ` Dmitry Vyukov
2017-03-24 14:09                 ` Peter Zijlstra
2017-03-17  0:15 ` [PATCH 7/7] crypto, x86, LLVM: aesni - fix token pasting Michael Davidson
2017-04-03 23:14   ` Matthias Kaehlcke
2017-03-17  8:17 ` [PATCH 0/7] LLVM: make x86_64 kernel build with clang Dmitry Vyukov

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