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Merge branch 'x86-hash-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull x86 hashing changes from Ingo Molnar:
 "Small fixes and cleanups to the librarized arch_fast_hash() methods,
  used by the net/openvswitch code"

* 'x86-hash-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, hash: Simplify switch, add __init annotation
  x86, hash: Swap arguments passed to crc32_u32()
  x86, hash: Fix build failure with older binutils
This commit is contained in:
Linus Torvalds 2014-03-31 12:27:32 -07:00
commit d9fcca40eb
2 changed files with 14 additions and 9 deletions
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1
arch/x86/Makefile
View file

@ -152,6 +152,7 @@ cfi-sections := $(call as-instr,.cfi_sections .debug_frame,-DCONFIG_AS_CFI_SECTI
# does binutils support specific instructions?
asinstr := $(call as-instr,fxsaveq (%rax),-DCONFIG_AS_FXSAVEQ=1)
asinstr += $(call as-instr,crc32l %eax$(comma)%eax,-DCONFIG_AS_CRC32=1)
avx_instr := $(call as-instr,vxorps %ymm0$(comma)%ymm1$(comma)%ymm2,-DCONFIG_AS_AVX=1)
avx2_instr :=$(call as-instr,vpbroadcastb %xmm0$(comma)%ymm1,-DCONFIG_AS_AVX2=1)

22
arch/x86/lib/hash.c
View file

@ -32,6 +32,7 @@
*/
#include <linux/hash.h>
#include <linux/init.h>
#include <asm/processor.h>
#include <asm/cpufeature.h>
@ -39,7 +40,11 @@
static inline u32 crc32_u32(u32 crc, u32 val)
{
#ifdef CONFIG_AS_CRC32
asm ("crc32l %1,%0\n" : "+r" (crc) : "rm" (val));
#else
asm (".byte 0xf2, 0x0f, 0x38, 0xf1, 0xc1" : "+a" (crc) : "c" (val));
#endif
return crc;
}
@ -49,19 +54,18 @@ static u32 intel_crc4_2_hash(const void *data, u32 len, u32 seed)
u32 i, tmp = 0;
for (i = 0; i < len / 4; i++)
seed = crc32_u32(*p32++, seed);
seed = crc32_u32(seed, *p32++);
switch (3 - (len & 0x03)) {
case 0:
switch (len & 3) {
case 3:
tmp |= *((const u8 *) p32 + 2) << 16;
/* fallthrough */
case 1:
case 2:
tmp |= *((const u8 *) p32 + 1) << 8;
/* fallthrough */
case 2:
case 1:
tmp |= *((const u8 *) p32);
seed = crc32_u32(tmp, seed);
default:
seed = crc32_u32(seed, tmp);
break;
}
@ -74,12 +78,12 @@ static u32 intel_crc4_2_hash2(const u32 *data, u32 len, u32 seed)
u32 i;
for (i = 0; i < len; i++)
seed = crc32_u32(*p32++, seed);
seed = crc32_u32(seed, *p32++);
return seed;
}
void setup_arch_fast_hash(struct fast_hash_ops *ops)
void __init setup_arch_fast_hash(struct fast_hash_ops *ops)
{
if (cpu_has_xmm4_2) {
ops->hash = intel_crc4_2_hash;