diff options
Diffstat (limited to 'arch/x86/lib/memset_64.S')
| -rw-r--r-- | arch/x86/lib/memset_64.S | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S new file mode 100644 index 00000000000..2c5948116bd --- /dev/null +++ b/arch/x86/lib/memset_64.S @@ -0,0 +1,133 @@ +/* Copyright 2002 Andi Kleen, SuSE Labs */ + +#include <linux/linkage.h> +#include <asm/dwarf2.h> + +/* + * ISO C memset - set a memory block to a byte value. + * + * rdi destination + * rsi value (char) + * rdx count (bytes) + * + * rax original destination + */ + ALIGN +memset_c: + CFI_STARTPROC + movq %rdi,%r9 + movl %edx,%r8d + andl $7,%r8d + movl %edx,%ecx + shrl $3,%ecx + /* expand byte value */ + movzbl %sil,%esi + movabs $0x0101010101010101,%rax + mulq %rsi /* with rax, clobbers rdx */ + rep stosq + movl %r8d,%ecx + rep stosb + movq %r9,%rax + ret + CFI_ENDPROC +ENDPROC(memset_c) + +ENTRY(memset) +ENTRY(__memset) + CFI_STARTPROC + movq %rdi,%r10 + movq %rdx,%r11 + + /* expand byte value */ + movzbl %sil,%ecx + movabs $0x0101010101010101,%rax + mul %rcx /* with rax, clobbers rdx */ + + /* align dst */ + movl %edi,%r9d + andl $7,%r9d + jnz .Lbad_alignment + CFI_REMEMBER_STATE +.Lafter_bad_alignment: + + movl %r11d,%ecx + shrl $6,%ecx + jz .Lhandle_tail + + .p2align 4 +.Lloop_64: + decl %ecx + movq %rax,(%rdi) + movq %rax,8(%rdi) + movq %rax,16(%rdi) + movq %rax,24(%rdi) + movq %rax,32(%rdi) + movq %rax,40(%rdi) + movq %rax,48(%rdi) + movq %rax,56(%rdi) + leaq 64(%rdi),%rdi + jnz .Lloop_64 + + /* Handle tail in loops. The loops should be faster than hard + to predict jump tables. */ + .p2align 4 +.Lhandle_tail: + movl %r11d,%ecx + andl $63&(~7),%ecx + jz .Lhandle_7 + shrl $3,%ecx + .p2align 4 +.Lloop_8: + decl %ecx + movq %rax,(%rdi) + leaq 8(%rdi),%rdi + jnz .Lloop_8 + +.Lhandle_7: + movl %r11d,%ecx + andl $7,%ecx + jz .Lende + .p2align 4 +.Lloop_1: + decl %ecx + movb %al,(%rdi) + leaq 1(%rdi),%rdi + jnz .Lloop_1 + +.Lende: + movq %r10,%rax + ret + + CFI_RESTORE_STATE +.Lbad_alignment: + cmpq $7,%r11 + jbe .Lhandle_7 + movq %rax,(%rdi) /* unaligned store */ + movq $8,%r8 + subq %r9,%r8 + addq %r8,%rdi + subq %r8,%r11 + jmp .Lafter_bad_alignment +.Lfinal: + CFI_ENDPROC +ENDPROC(memset) +ENDPROC(__memset) + + /* Some CPUs run faster using the string instructions. + It is also a lot simpler. Use this when possible */ + +#include <asm/cpufeature.h> + + .section .altinstr_replacement,"ax" +1: .byte 0xeb /* jmp <disp8> */ + .byte (memset_c - memset) - (2f - 1b) /* offset */ +2: + .previous + .section .altinstructions,"a" + .align 8 + .quad memset + .quad 1b + .byte X86_FEATURE_REP_GOOD + .byte .Lfinal - memset + .byte 2b - 1b + .previous |