1/* SPDX-License-Identifier: GPL-2.0-only */ 2/* 3 * Copyright (C) 2013 ARM Ltd. 4 * Copyright (C) 2013 Linaro. 5 * 6 * This code is based on glibc cortex strings work originally authored by Linaro 7 * be found @ 8 * 9 * http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/ 10 * files/head:/src/aarch64/ 11 */ 12 13#include <linux/linkage.h> 14#include <asm/assembler.h> 15#include <asm/cache.h> 16 17/* 18 * Fill in the buffer with character c (alignment handled by the hardware) 19 * 20 * Parameters: 21 * x0 - buf 22 * x1 - c 23 * x2 - n 24 * Returns: 25 * x0 - buf 26 */ 27 28dstin .req x0 29val .req w1 30count .req x2 31tmp1 .req x3 32tmp1w .req w3 33tmp2 .req x4 34tmp2w .req w4 35zva_len_x .req x5 36zva_len .req w5 37zva_bits_x .req x6 38 39A_l .req x7 40A_lw .req w7 41dst .req x8 42tmp3w .req w9 43tmp3 .req x9 44 45 .weak memset 46SYM_FUNC_START_ALIAS(__memset) 47SYM_FUNC_START_PI(memset) 48 mov dst, dstin /* Preserve return value. */ 49 and A_lw, val, #255 50 orr A_lw, A_lw, A_lw, lsl #8 51 orr A_lw, A_lw, A_lw, lsl #16 52 orr A_l, A_l, A_l, lsl #32 53 54 cmp count, #15 55 b.hi .Lover16_proc 56 /*All store maybe are non-aligned..*/ 57 tbz count, #3, 1f 58 str A_l, [dst], #8 591: 60 tbz count, #2, 2f 61 str A_lw, [dst], #4 622: 63 tbz count, #1, 3f 64 strh A_lw, [dst], #2 653: 66 tbz count, #0, 4f 67 strb A_lw, [dst] 684: 69 ret 70 71.Lover16_proc: 72 /*Whether the start address is aligned with 16.*/ 73 neg tmp2, dst 74 ands tmp2, tmp2, #15 75 b.eq .Laligned 76/* 77* The count is not less than 16, we can use stp to store the start 16 bytes, 78* then adjust the dst aligned with 16.This process will make the current 79* memory address at alignment boundary. 80*/ 81 stp A_l, A_l, [dst] /*non-aligned store..*/ 82 /*make the dst aligned..*/ 83 sub count, count, tmp2 84 add dst, dst, tmp2 85 86.Laligned: 87 cbz A_l, .Lzero_mem 88 89.Ltail_maybe_long: 90 cmp count, #64 91 b.ge .Lnot_short 92.Ltail63: 93 ands tmp1, count, #0x30 94 b.eq 3f 95 cmp tmp1w, #0x20 96 b.eq 1f 97 b.lt 2f 98 stp A_l, A_l, [dst], #16 991: 100 stp A_l, A_l, [dst], #16 1012: 102 stp A_l, A_l, [dst], #16 103/* 104* The last store length is less than 16,use stp to write last 16 bytes. 105* It will lead some bytes written twice and the access is non-aligned. 106*/ 1073: 108 ands count, count, #15 109 cbz count, 4f 110 add dst, dst, count 111 stp A_l, A_l, [dst, #-16] /* Repeat some/all of last store. */ 1124: 113 ret 114 115 /* 116 * Critical loop. Start at a new cache line boundary. Assuming 117 * 64 bytes per line, this ensures the entire loop is in one line. 118 */ 119 .p2align L1_CACHE_SHIFT 120.Lnot_short: 121 sub dst, dst, #16/* Pre-bias. */ 122 sub count, count, #64 1231: 124 stp A_l, A_l, [dst, #16] 125 stp A_l, A_l, [dst, #32] 126 stp A_l, A_l, [dst, #48] 127 stp A_l, A_l, [dst, #64]! 128 subs count, count, #64 129 b.ge 1b 130 tst count, #0x3f 131 add dst, dst, #16 132 b.ne .Ltail63 133.Lexitfunc: 134 ret 135 136 /* 137 * For zeroing memory, check to see if we can use the ZVA feature to 138 * zero entire 'cache' lines. 139 */ 140.Lzero_mem: 141 cmp count, #63 142 b.le .Ltail63 143 /* 144 * For zeroing small amounts of memory, it's not worth setting up 145 * the line-clear code. 146 */ 147 cmp count, #128 148 b.lt .Lnot_short /*count is at least 128 bytes*/ 149 150 mrs tmp1, dczid_el0 151 tbnz tmp1, #4, .Lnot_short 152 mov tmp3w, #4 153 and zva_len, tmp1w, #15 /* Safety: other bits reserved. */ 154 lsl zva_len, tmp3w, zva_len 155 156 ands tmp3w, zva_len, #63 157 /* 158 * ensure the zva_len is not less than 64. 159 * It is not meaningful to use ZVA if the block size is less than 64. 160 */ 161 b.ne .Lnot_short 162.Lzero_by_line: 163 /* 164 * Compute how far we need to go to become suitably aligned. We're 165 * already at quad-word alignment. 166 */ 167 cmp count, zva_len_x 168 b.lt .Lnot_short /* Not enough to reach alignment. */ 169 sub zva_bits_x, zva_len_x, #1 170 neg tmp2, dst 171 ands tmp2, tmp2, zva_bits_x 172 b.eq 2f /* Already aligned. */ 173 /* Not aligned, check that there's enough to copy after alignment.*/ 174 sub tmp1, count, tmp2 175 /* 176 * grantee the remain length to be ZVA is bigger than 64, 177 * avoid to make the 2f's process over mem range.*/ 178 cmp tmp1, #64 179 ccmp tmp1, zva_len_x, #8, ge /* NZCV=0b1000 */ 180 b.lt .Lnot_short 181 /* 182 * We know that there's at least 64 bytes to zero and that it's safe 183 * to overrun by 64 bytes. 184 */ 185 mov count, tmp1 1861: 187 stp A_l, A_l, [dst] 188 stp A_l, A_l, [dst, #16] 189 stp A_l, A_l, [dst, #32] 190 subs tmp2, tmp2, #64 191 stp A_l, A_l, [dst, #48] 192 add dst, dst, #64 193 b.ge 1b 194 /* We've overrun a bit, so adjust dst downwards.*/ 195 add dst, dst, tmp2 1962: 197 sub count, count, zva_len_x 1983: 199 dc zva, dst 200 add dst, dst, zva_len_x 201 subs count, count, zva_len_x 202 b.ge 3b 203 ands count, count, zva_bits_x 204 b.ne .Ltail_maybe_long 205 ret 206SYM_FUNC_END_PI(memset) 207EXPORT_SYMBOL(memset) 208SYM_FUNC_END_ALIAS(__memset) 209EXPORT_SYMBOL(__memset) 210