관리-도구

편집 파일: memcpy_64.S

/* SPDX-License-Identifier: GPL-2.0-only */ /* Copyright 2002 Andi Kleen */ #include <linux/export.h> #include <linux/linkage.h> #include <asm/errno.h> #include <asm/cpufeatures.h> #include <asm/alternative.h> .section .noinstr.text, "ax" /* * memcpy - Copy a memory block. * * Input: * rdi destination * rsi source * rdx count * * Output: * rax original destination * * The FSRM alternative should be done inline (avoiding the call and * the disgusting return handling), but that would require some help * from the compiler for better calling conventions. * * The 'rep movsb' itself is small enough to replace the call, but the * two register moves blow up the code. And one of them is "needed" * only for the return value that is the same as the source input, * which the compiler could/should do much better anyway. */ SYM_FUNC_START(__memcpy) ALTERNATIVE "jmp memcpy_orig", "", X86_FEATURE_FSRM movq %rdi, %rax movq %rdx, %rcx rep movsb RET SYM_FUNC_END(__memcpy) EXPORT_SYMBOL(__memcpy) SYM_FUNC_ALIAS_MEMFUNC(memcpy, __memcpy) EXPORT_SYMBOL(memcpy) SYM_FUNC_START_LOCAL(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) RET .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) RET .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) RET .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: RET SYM_FUNC_END(memcpy_orig)