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

Started byMatthias Kaehlcke <mka@chromium.org>
First post2017-06-23 00:40 +0200
Last post2017-06-30 20:40 +0200
Articles 3 — 2 participants

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  Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c Matthias Kaehlcke <mka@chromium.org> - 2017-06-23 00:40 +0200
    Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c "H. Peter Anvin" <hpa@zytor.com> - 2017-06-23 00:50 +0200
      Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c Matthias Kaehlcke <mka@chromium.org> - 2017-06-30 20:40 +0200

#1673096 — Re: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c

FromMatthias Kaehlcke <mka@chromium.org>
Date2017-06-23 00:40 +0200
SubjectRe: [PATCH 4/7] x86, boot, LLVM: #undef memcpy etc in string.c
Message-ID<tViVz-2hN-7@gated-at.bofh.it>
(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;

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#1673103

From"H. Peter Anvin" <hpa@zytor.com>
Date2017-06-23 00:50 +0200
Message-ID<tVj5g-2lh-17@gated-at.bofh.it>
In reply to#1673096
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

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#1679060

FromMatthias Kaehlcke <mka@chromium.org>
Date2017-06-30 20:40 +0200
Message-ID<tY8ZI-w7-9@gated-at.bofh.it>
In reply to#1673103
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@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>

Ingo, do you plan to pick this change?

Thanks

Matthias

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