/* 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