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x86, asm: Merge cmpxchg_486_u64() and cmpxchg8b_emu()

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We have two functions for doing exactly the same thing -- emulating
cmpxchg8b on 486 and older hardware -- with different calling
conventions, and yet doing the same thing.  Drop the C version and use
the assembly version, via alternatives, for both the local and
non-local versions of cmpxchg8b.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <AANLkTikAmaDPji-TVDarmG1yD=fwbffcsmEU=YEuP+8r@mail.gmail.com>
This commit is contained in:
H. Peter Anvin
2010-07-28 17:05:11 -07:00
parent 90c8f92f5c
commit a378d9338e
2 changed files with 14 additions and 34 deletions
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18
arch/x86/lib/cmpxchg.c
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@@ -52,21 +52,3 @@ unsigned long cmpxchg_386_u32(volatile void *ptr, u32 old, u32 new)
}
EXPORT_SYMBOL(cmpxchg_386_u32);
#endif
#ifndef CONFIG_X86_CMPXCHG64
unsigned long long cmpxchg_486_u64(volatile void *ptr, u64 old, u64 new)
{
u64 prev;
unsigned long flags;
/* Poor man's cmpxchg8b for 386 and 486. Unsuitable for SMP */
local_irq_save(flags);
prev = *(u64 *)ptr;
if (prev == old)
*(u64 *)ptr = new;
local_irq_restore(flags);
return prev;
}
EXPORT_SYMBOL(cmpxchg_486_u64);
#endif