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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 | /* * arch/xtensa/lib/strncpy_user.S * * This file is subject to the terms and conditions of the GNU General * Public License. See the file "COPYING" in the main directory of * this archive for more details. * * Returns: -EFAULT if exception before terminator, N if the entire * buffer filled, else strlen. * * Copyright (C) 2002 Tensilica Inc. */ #include <asm/variant/core.h> #include <linux/errno.h> /* Load or store instructions that may cause exceptions use the EX macro. */ #define EX(insn,reg1,reg2,offset,handler) \ 9: insn reg1, reg2, offset; \ .section __ex_table, "a"; \ .word 9b, handler; \ .previous /* * char *__strncpy_user(char *dst, const char *src, size_t len) */ .text .begin literal .align 4 .Lmask0: .byte 0xff, 0x00, 0x00, 0x00 .Lmask1: .byte 0x00, 0xff, 0x00, 0x00 .Lmask2: .byte 0x00, 0x00, 0xff, 0x00 .Lmask3: .byte 0x00, 0x00, 0x00, 0xff .end literal # Register use # a0/ return address # a1/ stack pointer # a2/ return value # a3/ src # a4/ len # a5/ mask0 # a6/ mask1 # a7/ mask2 # a8/ mask3 # a9/ tmp # a10/ tmp # a11/ dst # a12/ tmp .align 4 .global __strncpy_user .type __strncpy_user,@function __strncpy_user: entry sp, 16 # minimal stack frame # a2/ dst, a3/ src, a4/ len mov a11, a2 # leave dst in return value register beqz a4, .Lret # if len is zero l32r a5, .Lmask0 # mask for byte 0 l32r a6, .Lmask1 # mask for byte 1 l32r a7, .Lmask2 # mask for byte 2 l32r a8, .Lmask3 # mask for byte 3 bbsi.l a3, 0, .Lsrc1mod2 # if only 8-bit aligned bbsi.l a3, 1, .Lsrc2mod4 # if only 16-bit aligned .Lsrcaligned: # return here when src is word-aligned srli a12, a4, 2 # number of loop iterations with 4B per loop movi a9, 3 bnone a11, a9, .Laligned j .Ldstunaligned .Lsrc1mod2: # src address is odd EX(l8ui, a9, a3, 0, fixup_l) # get byte 0 addi a3, a3, 1 # advance src pointer EX(s8i, a9, a11, 0, fixup_s) # store byte 0 beqz a9, .Lret # if byte 0 is zero addi a11, a11, 1 # advance dst pointer addi a4, a4, -1 # decrement len beqz a4, .Lret # if len is zero bbci.l a3, 1, .Lsrcaligned # if src is now word-aligned .Lsrc2mod4: # src address is 2 mod 4 EX(l8ui, a9, a3, 0, fixup_l) # get byte 0 /* 1-cycle interlock */ EX(s8i, a9, a11, 0, fixup_s) # store byte 0 beqz a9, .Lret # if byte 0 is zero addi a11, a11, 1 # advance dst pointer addi a4, a4, -1 # decrement len beqz a4, .Lret # if len is zero EX(l8ui, a9, a3, 1, fixup_l) # get byte 0 addi a3, a3, 2 # advance src pointer EX(s8i, a9, a11, 0, fixup_s) # store byte 0 beqz a9, .Lret # if byte 0 is zero addi a11, a11, 1 # advance dst pointer addi a4, a4, -1 # decrement len bnez a4, .Lsrcaligned # if len is nonzero .Lret: sub a2, a11, a2 # compute strlen retw /* * dst is word-aligned, src is word-aligned */ .align 4 # 1 mod 4 alignment for LOOPNEZ .byte 0 # (0 mod 4 alignment for LBEG) .Laligned: #if XCHAL_HAVE_LOOPS loopnez a12, .Loop1done #else beqz a12, .Loop1done slli a12, a12, 2 add a12, a12, a11 # a12 = end of last 4B chunck #endif .Loop1: EX(l32i, a9, a3, 0, fixup_l) # get word from src addi a3, a3, 4 # advance src pointer bnone a9, a5, .Lz0 # if byte 0 is zero bnone a9, a6, .Lz1 # if byte 1 is zero bnone a9, a7, .Lz2 # if byte 2 is zero EX(s32i, a9, a11, 0, fixup_s) # store word to dst bnone a9, a8, .Lz3 # if byte 3 is zero addi a11, a11, 4 # advance dst pointer #if !XCHAL_HAVE_LOOPS blt a11, a12, .Loop1 #endif .Loop1done: bbci.l a4, 1, .L100 # copy 2 bytes EX(l16ui, a9, a3, 0, fixup_l) addi a3, a3, 2 # advance src pointer #ifdef __XTENSA_EB__ bnone a9, a7, .Lz0 # if byte 2 is zero bnone a9, a8, .Lz1 # if byte 3 is zero #else bnone a9, a5, .Lz0 # if byte 0 is zero bnone a9, a6, .Lz1 # if byte 1 is zero #endif EX(s16i, a9, a11, 0, fixup_s) addi a11, a11, 2 # advance dst pointer .L100: bbci.l a4, 0, .Lret EX(l8ui, a9, a3, 0, fixup_l) /* slot */ EX(s8i, a9, a11, 0, fixup_s) beqz a9, .Lret # if byte is zero addi a11, a11, 1-3 # advance dst ptr 1, but also cancel # the effect of adding 3 in .Lz3 code /* fall thru to .Lz3 and "retw" */ .Lz3: # byte 3 is zero addi a11, a11, 3 # advance dst pointer sub a2, a11, a2 # compute strlen retw .Lz0: # byte 0 is zero #ifdef __XTENSA_EB__ movi a9, 0 #endif /* __XTENSA_EB__ */ EX(s8i, a9, a11, 0, fixup_s) sub a2, a11, a2 # compute strlen retw .Lz1: # byte 1 is zero #ifdef __XTENSA_EB__ extui a9, a9, 16, 16 #endif /* __XTENSA_EB__ */ EX(s16i, a9, a11, 0, fixup_s) addi a11, a11, 1 # advance dst pointer sub a2, a11, a2 # compute strlen retw .Lz2: # byte 2 is zero #ifdef __XTENSA_EB__ extui a9, a9, 16, 16 #endif /* __XTENSA_EB__ */ EX(s16i, a9, a11, 0, fixup_s) movi a9, 0 EX(s8i, a9, a11, 2, fixup_s) addi a11, a11, 2 # advance dst pointer sub a2, a11, a2 # compute strlen retw .align 4 # 1 mod 4 alignment for LOOPNEZ .byte 0 # (0 mod 4 alignment for LBEG) .Ldstunaligned: /* * for now just use byte copy loop */ #if XCHAL_HAVE_LOOPS loopnez a4, .Lunalignedend #else beqz a4, .Lunalignedend add a12, a11, a4 # a12 = ending address #endif /* XCHAL_HAVE_LOOPS */ .Lnextbyte: EX(l8ui, a9, a3, 0, fixup_l) addi a3, a3, 1 EX(s8i, a9, a11, 0, fixup_s) beqz a9, .Lunalignedend addi a11, a11, 1 #if !XCHAL_HAVE_LOOPS blt a11, a12, .Lnextbyte #endif .Lunalignedend: sub a2, a11, a2 # compute strlen retw .section .fixup, "ax" .align 4 /* For now, just return -EFAULT. Future implementations might * like to clear remaining kernel space, like the fixup * implementation in memset(). Thus, we differentiate between * load/store fixups. */ fixup_s: fixup_l: movi a2, -EFAULT retw |