| /* Copyright 2002 Andi Kleen */ | |
| #include <linux/linkage.h> | |
| #include <asm/cpufeature.h> | |
| #include <asm/alternative-asm.h> | |
| /* | |
| * We build a jump to memcpy_orig by default which gets NOPped out on | |
| * the majority of x86 CPUs which set REP_GOOD. In addition, CPUs which | |
| * have the enhanced REP MOVSB/STOSB feature (ERMS), change those NOPs | |
| * to a jmp to memcpy_erms which does the REP; MOVSB mem copy. | |
| */ | |
| .weak memcpy | |
| /* | |
| * memcpy - Copy a memory block. | |
| * | |
| * Input: | |
| * rdi destination | |
| * rsi source | |
| * rdx count | |
| * | |
| * Output: | |
| * rax original destination | |
| */ | |
| ENTRY(__memcpy) | |
| ENTRY(memcpy) | |
| ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \ | |
| "jmp memcpy_erms", X86_FEATURE_ERMS | |
| movq %rdi, %rax | |
| movq %rdx, %rcx | |
| shrq $3, %rcx | |
| andl $7, %edx | |
| rep movsq | |
| movl %edx, %ecx | |
| rep movsb | |
| ret | |
| ENDPROC(memcpy) | |
| ENDPROC(__memcpy) | |
| /* | |
| * memcpy_erms() - enhanced fast string memcpy. This is faster and | |
| * simpler than memcpy. Use memcpy_erms when possible. | |
| */ | |
| ENTRY(memcpy_erms) | |
| movq %rdi, %rax | |
| movq %rdx, %rcx | |
| rep movsb | |
| ret | |
| ENDPROC(memcpy_erms) | |
| ENTRY(memcpy_orig) | |
| movq %rdi, %rax | |
| cmpq $0x20, %rdx | |
| jb .Lhandle_tail | |
| /* | |
| * We check whether memory false dependence could occur, | |
| * then jump to corresponding copy mode. | |
| */ | |
| cmp %dil, %sil | |
| jl .Lcopy_backward | |
| subq $0x20, %rdx | |
| .Lcopy_forward_loop: | |
| subq $0x20, %rdx | |
| /* | |
| * Move in blocks of 4x8 bytes: | |
| */ | |
| movq 0*8(%rsi), %r8 | |
| movq 1*8(%rsi), %r9 | |
| movq 2*8(%rsi), %r10 | |
| movq 3*8(%rsi), %r11 | |
| leaq 4*8(%rsi), %rsi | |
| movq %r8, 0*8(%rdi) | |
| movq %r9, 1*8(%rdi) | |
| movq %r10, 2*8(%rdi) | |
| movq %r11, 3*8(%rdi) | |
| leaq 4*8(%rdi), %rdi | |
| jae .Lcopy_forward_loop | |
| addl $0x20, %edx | |
| jmp .Lhandle_tail | |
| .Lcopy_backward: | |
| /* | |
| * Calculate copy position to tail. | |
| */ | |
| addq %rdx, %rsi | |
| addq %rdx, %rdi | |
| subq $0x20, %rdx | |
| /* | |
| * At most 3 ALU operations in one cycle, | |
| * so append NOPS in the same 16 bytes trunk. | |
| */ | |
| .p2align 4 | |
| .Lcopy_backward_loop: | |
| subq $0x20, %rdx | |
| movq -1*8(%rsi), %r8 | |
| movq -2*8(%rsi), %r9 | |
| movq -3*8(%rsi), %r10 | |
| movq -4*8(%rsi), %r11 | |
| leaq -4*8(%rsi), %rsi | |
| movq %r8, -1*8(%rdi) | |
| movq %r9, -2*8(%rdi) | |
| movq %r10, -3*8(%rdi) | |
| movq %r11, -4*8(%rdi) | |
| leaq -4*8(%rdi), %rdi | |
| jae .Lcopy_backward_loop | |
| /* | |
| * Calculate copy position to head. | |
| */ | |
| addl $0x20, %edx | |
| subq %rdx, %rsi | |
| subq %rdx, %rdi | |
| .Lhandle_tail: | |
| cmpl $16, %edx | |
| jb .Lless_16bytes | |
| /* | |
| * Move data from 16 bytes to 31 bytes. | |
| */ | |
| movq 0*8(%rsi), %r8 | |
| movq 1*8(%rsi), %r9 | |
| movq -2*8(%rsi, %rdx), %r10 | |
| movq -1*8(%rsi, %rdx), %r11 | |
| movq %r8, 0*8(%rdi) | |
| movq %r9, 1*8(%rdi) | |
| movq %r10, -2*8(%rdi, %rdx) | |
| movq %r11, -1*8(%rdi, %rdx) | |
| retq | |
| .p2align 4 | |
| .Lless_16bytes: | |
| cmpl $8, %edx | |
| jb .Lless_8bytes | |
| /* | |
| * Move data from 8 bytes to 15 bytes. | |
| */ | |
| movq 0*8(%rsi), %r8 | |
| movq -1*8(%rsi, %rdx), %r9 | |
| movq %r8, 0*8(%rdi) | |
| movq %r9, -1*8(%rdi, %rdx) | |
| retq | |
| .p2align 4 | |
| .Lless_8bytes: | |
| cmpl $4, %edx | |
| jb .Lless_3bytes | |
| /* | |
| * Move data from 4 bytes to 7 bytes. | |
| */ | |
| movl (%rsi), %ecx | |
| movl -4(%rsi, %rdx), %r8d | |
| movl %ecx, (%rdi) | |
| movl %r8d, -4(%rdi, %rdx) | |
| retq | |
| .p2align 4 | |
| .Lless_3bytes: | |
| subl $1, %edx | |
| jb .Lend | |
| /* | |
| * Move data from 1 bytes to 3 bytes. | |
| */ | |
| movzbl (%rsi), %ecx | |
| jz .Lstore_1byte | |
| movzbq 1(%rsi), %r8 | |
| movzbq (%rsi, %rdx), %r9 | |
| movb %r8b, 1(%rdi) | |
| movb %r9b, (%rdi, %rdx) | |
| .Lstore_1byte: | |
| movb %cl, (%rdi) | |
| .Lend: | |
| retq | |
| ENDPROC(memcpy_orig) |