1/* 2 * Normally compiler builtins are used, but sometimes the compiler calls out 3 * of line code. Based on asm-i386/string.h. 4 * 5 * This assembly file is re-written from memmove_64.c file. 6 * - Copyright 2011 Fenghua Yu <fenghua.yu@intel.com> 7 */ 8#include <linux/linkage.h> 9#include <asm/cpufeatures.h> 10#include <asm/alternative-asm.h> 11#include <asm/export.h> 12 13#undef memmove 14 15/* 16 * Implement memmove(). This can handle overlap between src and dst. 17 * 18 * Input: 19 * rdi: dest 20 * rsi: src 21 * rdx: count 22 * 23 * Output: 24 * rax: dest 25 */ 26.weak memmove 27 28ENTRY(memmove) 29ENTRY(__memmove) 30 31 /* Handle more 32 bytes in loop */ 32 mov %rdi, %rax 33 cmp $0x20, %rdx 34 jb 1f 35 36 /* Decide forward/backward copy mode */ 37 cmp %rdi, %rsi 38 jge .Lmemmove_begin_forward 39 mov %rsi, %r8 40 add %rdx, %r8 41 cmp %rdi, %r8 42 jg 2f 43 44.Lmemmove_begin_forward: 45 ALTERNATIVE "", "movq %rdx, %rcx; rep movsb; retq", X86_FEATURE_ERMS 46 47 /* 48 * movsq instruction have many startup latency 49 * so we handle small size by general register. 50 */ 51 cmp $680, %rdx 52 jb 3f 53 /* 54 * movsq instruction is only good for aligned case. 55 */ 56 57 cmpb %dil, %sil 58 je 4f 593: 60 sub $0x20, %rdx 61 /* 62 * We gobble 32 bytes forward in each loop. 63 */ 645: 65 sub $0x20, %rdx 66 movq 0*8(%rsi), %r11 67 movq 1*8(%rsi), %r10 68 movq 2*8(%rsi), %r9 69 movq 3*8(%rsi), %r8 70 leaq 4*8(%rsi), %rsi 71 72 movq %r11, 0*8(%rdi) 73 movq %r10, 1*8(%rdi) 74 movq %r9, 2*8(%rdi) 75 movq %r8, 3*8(%rdi) 76 leaq 4*8(%rdi), %rdi 77 jae 5b 78 addq $0x20, %rdx 79 jmp 1f 80 /* 81 * Handle data forward by movsq. 82 */ 83 .p2align 4 844: 85 movq %rdx, %rcx 86 movq -8(%rsi, %rdx), %r11 87 lea -8(%rdi, %rdx), %r10 88 shrq $3, %rcx 89 rep movsq 90 movq %r11, (%r10) 91 jmp 13f 92.Lmemmove_end_forward: 93 94 /* 95 * Handle data backward by movsq. 96 */ 97 .p2align 4 987: 99 movq %rdx, %rcx 100 movq (%rsi), %r11 101 movq %rdi, %r10 102 leaq -8(%rsi, %rdx), %rsi 103 leaq -8(%rdi, %rdx), %rdi 104 shrq $3, %rcx 105 std 106 rep movsq 107 cld 108 movq %r11, (%r10) 109 jmp 13f 110 111 /* 112 * Start to prepare for backward copy. 113 */ 114 .p2align 4 1152: 116 cmp $680, %rdx 117 jb 6f 118 cmp %dil, %sil 119 je 7b 1206: 121 /* 122 * Calculate copy position to tail. 123 */ 124 addq %rdx, %rsi 125 addq %rdx, %rdi 126 subq $0x20, %rdx 127 /* 128 * We gobble 32 bytes backward in each loop. 129 */ 1308: 131 subq $0x20, %rdx 132 movq -1*8(%rsi), %r11 133 movq -2*8(%rsi), %r10 134 movq -3*8(%rsi), %r9 135 movq -4*8(%rsi), %r8 136 leaq -4*8(%rsi), %rsi 137 138 movq %r11, -1*8(%rdi) 139 movq %r10, -2*8(%rdi) 140 movq %r9, -3*8(%rdi) 141 movq %r8, -4*8(%rdi) 142 leaq -4*8(%rdi), %rdi 143 jae 8b 144 /* 145 * Calculate copy position to head. 146 */ 147 addq $0x20, %rdx 148 subq %rdx, %rsi 149 subq %rdx, %rdi 1501: 151 cmpq $16, %rdx 152 jb 9f 153 /* 154 * Move data from 16 bytes to 31 bytes. 155 */ 156 movq 0*8(%rsi), %r11 157 movq 1*8(%rsi), %r10 158 movq -2*8(%rsi, %rdx), %r9 159 movq -1*8(%rsi, %rdx), %r8 160 movq %r11, 0*8(%rdi) 161 movq %r10, 1*8(%rdi) 162 movq %r9, -2*8(%rdi, %rdx) 163 movq %r8, -1*8(%rdi, %rdx) 164 jmp 13f 165 .p2align 4 1669: 167 cmpq $8, %rdx 168 jb 10f 169 /* 170 * Move data from 8 bytes to 15 bytes. 171 */ 172 movq 0*8(%rsi), %r11 173 movq -1*8(%rsi, %rdx), %r10 174 movq %r11, 0*8(%rdi) 175 movq %r10, -1*8(%rdi, %rdx) 176 jmp 13f 17710: 178 cmpq $4, %rdx 179 jb 11f 180 /* 181 * Move data from 4 bytes to 7 bytes. 182 */ 183 movl (%rsi), %r11d 184 movl -4(%rsi, %rdx), %r10d 185 movl %r11d, (%rdi) 186 movl %r10d, -4(%rdi, %rdx) 187 jmp 13f 18811: 189 cmp $2, %rdx 190 jb 12f 191 /* 192 * Move data from 2 bytes to 3 bytes. 193 */ 194 movw (%rsi), %r11w 195 movw -2(%rsi, %rdx), %r10w 196 movw %r11w, (%rdi) 197 movw %r10w, -2(%rdi, %rdx) 198 jmp 13f 19912: 200 cmp $1, %rdx 201 jb 13f 202 /* 203 * Move data for 1 byte. 204 */ 205 movb (%rsi), %r11b 206 movb %r11b, (%rdi) 20713: 208 retq 209ENDPROC(__memmove) 210ENDPROC(memmove) 211EXPORT_SYMBOL(__memmove) 212EXPORT_SYMBOL(memmove) 213