1/* SPDX-License-Identifier: GPL-2.0 */ 2/* 3 * Normally compiler builtins are used, but sometimes the compiler calls out 4 * of line code. Based on asm-i386/string.h. 5 * 6 * This assembly file is re-written from memmove_64.c file. 7 * - Copyright 2011 Fenghua Yu <fenghua.yu@intel.com> 8 */ 9#include <linux/linkage.h> 10#include <asm/cpufeatures.h> 11#include <asm/alternative-asm.h> 12#include <asm/export.h> 13 14#undef memmove 15 16/* 17 * Implement memmove(). This can handle overlap between src and dst. 18 * 19 * Input: 20 * rdi: dest 21 * rsi: src 22 * rdx: count 23 * 24 * Output: 25 * rax: dest 26 */ 27.weak memmove 28 29SYM_FUNC_START_ALIAS(memmove) 30SYM_FUNC_START(__memmove) 31 32 /* Handle more 32 bytes in loop */ 33 mov %rdi, %rax 34 cmp $0x20, %rdx 35 jb 1f 36 37 /* Decide forward/backward copy mode */ 38 cmp %rdi, %rsi 39 jge .Lmemmove_begin_forward 40 mov %rsi, %r8 41 add %rdx, %r8 42 cmp %rdi, %r8 43 jg 2f 44 45.Lmemmove_begin_forward: 46 ALTERNATIVE "", "movq %rdx, %rcx; rep movsb; retq", X86_FEATURE_ERMS 47 48 /* 49 * movsq instruction have many startup latency 50 * so we handle small size by general register. 51 */ 52 cmp $680, %rdx 53 jb 3f 54 /* 55 * movsq instruction is only good for aligned case. 56 */ 57 58 cmpb %dil, %sil 59 je 4f 603: 61 sub $0x20, %rdx 62 /* 63 * We gobble 32 bytes forward in each loop. 64 */ 655: 66 sub $0x20, %rdx 67 movq 0*8(%rsi), %r11 68 movq 1*8(%rsi), %r10 69 movq 2*8(%rsi), %r9 70 movq 3*8(%rsi), %r8 71 leaq 4*8(%rsi), %rsi 72 73 movq %r11, 0*8(%rdi) 74 movq %r10, 1*8(%rdi) 75 movq %r9, 2*8(%rdi) 76 movq %r8, 3*8(%rdi) 77 leaq 4*8(%rdi), %rdi 78 jae 5b 79 addq $0x20, %rdx 80 jmp 1f 81 /* 82 * Handle data forward by movsq. 83 */ 84 .p2align 4 854: 86 movq %rdx, %rcx 87 movq -8(%rsi, %rdx), %r11 88 lea -8(%rdi, %rdx), %r10 89 shrq $3, %rcx 90 rep movsq 91 movq %r11, (%r10) 92 jmp 13f 93.Lmemmove_end_forward: 94 95 /* 96 * Handle data backward by movsq. 97 */ 98 .p2align 4 997: 100 movq %rdx, %rcx 101 movq (%rsi), %r11 102 movq %rdi, %r10 103 leaq -8(%rsi, %rdx), %rsi 104 leaq -8(%rdi, %rdx), %rdi 105 shrq $3, %rcx 106 std 107 rep movsq 108 cld 109 movq %r11, (%r10) 110 jmp 13f 111 112 /* 113 * Start to prepare for backward copy. 114 */ 115 .p2align 4 1162: 117 cmp $680, %rdx 118 jb 6f 119 cmp %dil, %sil 120 je 7b 1216: 122 /* 123 * Calculate copy position to tail. 124 */ 125 addq %rdx, %rsi 126 addq %rdx, %rdi 127 subq $0x20, %rdx 128 /* 129 * We gobble 32 bytes backward in each loop. 130 */ 1318: 132 subq $0x20, %rdx 133 movq -1*8(%rsi), %r11 134 movq -2*8(%rsi), %r10 135 movq -3*8(%rsi), %r9 136 movq -4*8(%rsi), %r8 137 leaq -4*8(%rsi), %rsi 138 139 movq %r11, -1*8(%rdi) 140 movq %r10, -2*8(%rdi) 141 movq %r9, -3*8(%rdi) 142 movq %r8, -4*8(%rdi) 143 leaq -4*8(%rdi), %rdi 144 jae 8b 145 /* 146 * Calculate copy position to head. 147 */ 148 addq $0x20, %rdx 149 subq %rdx, %rsi 150 subq %rdx, %rdi 1511: 152 cmpq $16, %rdx 153 jb 9f 154 /* 155 * Move data from 16 bytes to 31 bytes. 156 */ 157 movq 0*8(%rsi), %r11 158 movq 1*8(%rsi), %r10 159 movq -2*8(%rsi, %rdx), %r9 160 movq -1*8(%rsi, %rdx), %r8 161 movq %r11, 0*8(%rdi) 162 movq %r10, 1*8(%rdi) 163 movq %r9, -2*8(%rdi, %rdx) 164 movq %r8, -1*8(%rdi, %rdx) 165 jmp 13f 166 .p2align 4 1679: 168 cmpq $8, %rdx 169 jb 10f 170 /* 171 * Move data from 8 bytes to 15 bytes. 172 */ 173 movq 0*8(%rsi), %r11 174 movq -1*8(%rsi, %rdx), %r10 175 movq %r11, 0*8(%rdi) 176 movq %r10, -1*8(%rdi, %rdx) 177 jmp 13f 17810: 179 cmpq $4, %rdx 180 jb 11f 181 /* 182 * Move data from 4 bytes to 7 bytes. 183 */ 184 movl (%rsi), %r11d 185 movl -4(%rsi, %rdx), %r10d 186 movl %r11d, (%rdi) 187 movl %r10d, -4(%rdi, %rdx) 188 jmp 13f 18911: 190 cmp $2, %rdx 191 jb 12f 192 /* 193 * Move data from 2 bytes to 3 bytes. 194 */ 195 movw (%rsi), %r11w 196 movw -2(%rsi, %rdx), %r10w 197 movw %r11w, (%rdi) 198 movw %r10w, -2(%rdi, %rdx) 199 jmp 13f 20012: 201 cmp $1, %rdx 202 jb 13f 203 /* 204 * Move data for 1 byte. 205 */ 206 movb (%rsi), %r11b 207 movb %r11b, (%rdi) 20813: 209 retq 210SYM_FUNC_END(__memmove) 211SYM_FUNC_END_ALIAS(memmove) 212EXPORT_SYMBOL(__memmove) 213EXPORT_SYMBOL(memmove) 214