1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* Copyright 2002 Andi Kleen */ 3 4#include <linux/linkage.h> 5#include <linux/cfi_types.h> 6#include <asm/errno.h> 7#include <asm/cpufeatures.h> 8#include <asm/alternative.h> 9#include <asm/export.h> 10 11.pushsection .noinstr.text, "ax" 12 13/* 14 * We build a jump to memcpy_orig by default which gets NOPped out on 15 * the majority of x86 CPUs which set REP_GOOD. In addition, CPUs which 16 * have the enhanced REP MOVSB/STOSB feature (ERMS), change those NOPs 17 * to a jmp to memcpy_erms which does the REP; MOVSB mem copy. 18 */ 19 20/* 21 * memcpy - Copy a memory block. 22 * 23 * Input: 24 * rdi destination 25 * rsi source 26 * rdx count 27 * 28 * Output: 29 * rax original destination 30 */ 31SYM_TYPED_FUNC_START(__memcpy) 32 ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \ 33 "jmp memcpy_erms", X86_FEATURE_ERMS 34 35 movq %rdi, %rax 36 movq %rdx, %rcx 37 shrq $3, %rcx 38 andl $7, %edx 39 rep movsq 40 movl %edx, %ecx 41 rep movsb 42 RET 43SYM_FUNC_END(__memcpy) 44EXPORT_SYMBOL(__memcpy) 45 46SYM_FUNC_ALIAS_WEAK(memcpy, __memcpy) 47EXPORT_SYMBOL(memcpy) 48 49/* 50 * memcpy_erms() - enhanced fast string memcpy. This is faster and 51 * simpler than memcpy. Use memcpy_erms when possible. 52 */ 53SYM_FUNC_START_LOCAL(memcpy_erms) 54 movq %rdi, %rax 55 movq %rdx, %rcx 56 rep movsb 57 RET 58SYM_FUNC_END(memcpy_erms) 59 60SYM_FUNC_START_LOCAL(memcpy_orig) 61 movq %rdi, %rax 62 63 cmpq $0x20, %rdx 64 jb .Lhandle_tail 65 66 /* 67 * We check whether memory false dependence could occur, 68 * then jump to corresponding copy mode. 69 */ 70 cmp %dil, %sil 71 jl .Lcopy_backward 72 subq $0x20, %rdx 73.Lcopy_forward_loop: 74 subq $0x20, %rdx 75 76 /* 77 * Move in blocks of 4x8 bytes: 78 */ 79 movq 0*8(%rsi), %r8 80 movq 1*8(%rsi), %r9 81 movq 2*8(%rsi), %r10 82 movq 3*8(%rsi), %r11 83 leaq 4*8(%rsi), %rsi 84 85 movq %r8, 0*8(%rdi) 86 movq %r9, 1*8(%rdi) 87 movq %r10, 2*8(%rdi) 88 movq %r11, 3*8(%rdi) 89 leaq 4*8(%rdi), %rdi 90 jae .Lcopy_forward_loop 91 addl $0x20, %edx 92 jmp .Lhandle_tail 93 94.Lcopy_backward: 95 /* 96 * Calculate copy position to tail. 97 */ 98 addq %rdx, %rsi 99 addq %rdx, %rdi 100 subq $0x20, %rdx 101 /* 102 * At most 3 ALU operations in one cycle, 103 * so append NOPS in the same 16 bytes trunk. 104 */ 105 .p2align 4 106.Lcopy_backward_loop: 107 subq $0x20, %rdx 108 movq -1*8(%rsi), %r8 109 movq -2*8(%rsi), %r9 110 movq -3*8(%rsi), %r10 111 movq -4*8(%rsi), %r11 112 leaq -4*8(%rsi), %rsi 113 movq %r8, -1*8(%rdi) 114 movq %r9, -2*8(%rdi) 115 movq %r10, -3*8(%rdi) 116 movq %r11, -4*8(%rdi) 117 leaq -4*8(%rdi), %rdi 118 jae .Lcopy_backward_loop 119 120 /* 121 * Calculate copy position to head. 122 */ 123 addl $0x20, %edx 124 subq %rdx, %rsi 125 subq %rdx, %rdi 126.Lhandle_tail: 127 cmpl $16, %edx 128 jb .Lless_16bytes 129 130 /* 131 * Move data from 16 bytes to 31 bytes. 132 */ 133 movq 0*8(%rsi), %r8 134 movq 1*8(%rsi), %r9 135 movq -2*8(%rsi, %rdx), %r10 136 movq -1*8(%rsi, %rdx), %r11 137 movq %r8, 0*8(%rdi) 138 movq %r9, 1*8(%rdi) 139 movq %r10, -2*8(%rdi, %rdx) 140 movq %r11, -1*8(%rdi, %rdx) 141 RET 142 .p2align 4 143.Lless_16bytes: 144 cmpl $8, %edx 145 jb .Lless_8bytes 146 /* 147 * Move data from 8 bytes to 15 bytes. 148 */ 149 movq 0*8(%rsi), %r8 150 movq -1*8(%rsi, %rdx), %r9 151 movq %r8, 0*8(%rdi) 152 movq %r9, -1*8(%rdi, %rdx) 153 RET 154 .p2align 4 155.Lless_8bytes: 156 cmpl $4, %edx 157 jb .Lless_3bytes 158 159 /* 160 * Move data from 4 bytes to 7 bytes. 161 */ 162 movl (%rsi), %ecx 163 movl -4(%rsi, %rdx), %r8d 164 movl %ecx, (%rdi) 165 movl %r8d, -4(%rdi, %rdx) 166 RET 167 .p2align 4 168.Lless_3bytes: 169 subl $1, %edx 170 jb .Lend 171 /* 172 * Move data from 1 bytes to 3 bytes. 173 */ 174 movzbl (%rsi), %ecx 175 jz .Lstore_1byte 176 movzbq 1(%rsi), %r8 177 movzbq (%rsi, %rdx), %r9 178 movb %r8b, 1(%rdi) 179 movb %r9b, (%rdi, %rdx) 180.Lstore_1byte: 181 movb %cl, (%rdi) 182 183.Lend: 184 RET 185SYM_FUNC_END(memcpy_orig) 186 187.popsection 188