Messages in this thread | | | Subject | Re: [PATCH v3] x86: Alias memset to __builtin_memset. | From | Bernd Petrovitsch <> | Date | Wed, 25 Mar 2020 12:33:11 +0100 |
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Hi all!
Sry for being late at the party:
On 24/03/2020 16:59, Clement Courbet wrote: [...] > --- > arch/x86/include/asm/string_64.h | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h > index 75314c3dbe47..9cfce0a840a4 100644 > --- a/arch/x86/include/asm/string_64.h > +++ b/arch/x86/include/asm/string_64.h > @@ -18,6 +18,15 @@ extern void *__memcpy(void *to, const void *from, size_t len); > void *memset(void *s, int c, size_t n); > void *__memset(void *s, int c, size_t n); > > +/* Recent compilers can generate much better code for known size and/or > + * fill values, and will fallback on `memset` if they fail. > + * We alias `memset` to `__builtin_memset` explicitly to inform the compiler to > + * perform this optimization even when -ffreestanding is used. > + */ > +#if !defined(CONFIG_FORTIFY_SOURCE) > +#define memset(s, c, count) __builtin_memset(s, c, count) To be on the safe side, the usual way to write macros is like
#define memset(s, c, count) __builtin_memset((s), (c), (count))
as no one know what is passed as parameter to memset() and the extra pair of parentheses don't hurt.
And similar below (and I fear there are more places).
Or did I miss something in the Kernel?
> +#endif > + > #define __HAVE_ARCH_MEMSET16 > static inline void *memset16(uint16_t *s, uint16_t v, size_t n) > { > @@ -74,6 +83,7 @@ int strcmp(const char *cs, const char *ct); > #undef memcpy > #define memcpy(dst, src, len) __memcpy(dst, src, len) #define memcpy(dst, src, len) __memcpy((dst), (src), (len)) > #define memmove(dst, src, len) __memmove(dst, src, len) #define memmove(dst, src, len) __memmove((dst), (src), (len)) > +#undef memset > #define memset(s, c, n) __memset(s, c, n) #define memset(s, c, n) __memset((s), (c), (n)) > > #ifndef __NO_FORTIFY >
MfG, Bernd -- Bernd Petrovitsch Email : bernd@petrovitsch.priv.at LUGA : http://www.luga.at
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