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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-03 23:38:28 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-03 23:38:28 +0300 |
| commit | 48b5259cf0a2b86b978da122f9459e22a2d1e8f6 (patch) | |
| tree | ced4acaed86bc4529458dd6b246ccae2ff2f0793 | |
| parent | 2a275382a4f78f386db3473d9bb9987580de3cf4 (diff) | |
| parent | 236222d39347e0e486010f10c1493e83dbbdfba8 (diff) | |
| download | linux-48b5259cf0a2b86b978da122f9459e22a2d1e8f6.tar.xz | |
Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 asm updates from Ingo Molnar:
"A single commit micro-optimizing short user copies on certain Intel
CPUs"
* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/uaccess: Optimize copy_user_enhanced_fast_string() for short strings
| -rw-r--r-- | arch/x86/lib/copy_user_64.S | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S index c5959576c315..020f75cc8cf6 100644 --- a/arch/x86/lib/copy_user_64.S +++ b/arch/x86/lib/copy_user_64.S @@ -37,7 +37,7 @@ ENTRY(copy_user_generic_unrolled) movl %edx,%ecx andl $63,%edx shrl $6,%ecx - jz 17f + jz .L_copy_short_string 1: movq (%rsi),%r8 2: movq 1*8(%rsi),%r9 3: movq 2*8(%rsi),%r10 @@ -58,7 +58,8 @@ ENTRY(copy_user_generic_unrolled) leaq 64(%rdi),%rdi decl %ecx jnz 1b -17: movl %edx,%ecx +.L_copy_short_string: + movl %edx,%ecx andl $7,%edx shrl $3,%ecx jz 20f @@ -174,6 +175,8 @@ EXPORT_SYMBOL(copy_user_generic_string) */ ENTRY(copy_user_enhanced_fast_string) ASM_STAC + cmpl $64,%edx + jb .L_copy_short_string /* less then 64 bytes, avoid the costly 'rep' */ movl %edx,%ecx 1: rep movsb |