Chris Zankel | 249ac17 | 2005-06-23 22:01:20 -0700 | [diff] [blame] | 1 | /* |
| 2 | * arch/xtensa/lib/usercopy.S |
| 3 | * |
| 4 | * Copy to/from user space (derived from arch/xtensa/lib/hal/memcopy.S) |
| 5 | * |
| 6 | * DO NOT COMBINE this function with <arch/xtensa/lib/hal/memcopy.S>. |
| 7 | * It needs to remain separate and distinct. The hal files are part |
Matt LaPlante | 4b3f686 | 2006-10-03 22:21:02 +0200 | [diff] [blame] | 8 | * of the Xtensa link-time HAL, and those files may differ per |
Chris Zankel | 249ac17 | 2005-06-23 22:01:20 -0700 | [diff] [blame] | 9 | * processor configuration. Patching the kernel for another |
| 10 | * processor configuration includes replacing the hal files, and we |
Matt LaPlante | 4b3f686 | 2006-10-03 22:21:02 +0200 | [diff] [blame] | 11 | * could lose the special functionality for accessing user-space |
Chris Zankel | 249ac17 | 2005-06-23 22:01:20 -0700 | [diff] [blame] | 12 | * memory during such a patch. We sacrifice a little code space here |
| 13 | * in favor to simplify code maintenance. |
| 14 | * |
| 15 | * This file is subject to the terms and conditions of the GNU General |
| 16 | * Public License. See the file "COPYING" in the main directory of |
| 17 | * this archive for more details. |
| 18 | * |
| 19 | * Copyright (C) 2002 Tensilica Inc. |
| 20 | */ |
| 21 | |
| 22 | |
| 23 | /* |
| 24 | * size_t __xtensa_copy_user (void *dst, const void *src, size_t len); |
| 25 | * |
| 26 | * The returned value is the number of bytes not copied. Implies zero |
| 27 | * is success. |
| 28 | * |
| 29 | * The general case algorithm is as follows: |
| 30 | * If the destination and source are both aligned, |
| 31 | * do 16B chunks with a loop, and then finish up with |
| 32 | * 8B, 4B, 2B, and 1B copies conditional on the length. |
| 33 | * If destination is aligned and source unaligned, |
| 34 | * do the same, but use SRC to align the source data. |
| 35 | * If destination is unaligned, align it by conditionally |
| 36 | * copying 1B and 2B and then retest. |
| 37 | * This code tries to use fall-through braches for the common |
| 38 | * case of aligned destinations (except for the branches to |
| 39 | * the alignment label). |
| 40 | * |
| 41 | * Register use: |
| 42 | * a0/ return address |
| 43 | * a1/ stack pointer |
| 44 | * a2/ return value |
| 45 | * a3/ src |
| 46 | * a4/ length |
| 47 | * a5/ dst |
| 48 | * a6/ tmp |
| 49 | * a7/ tmp |
| 50 | * a8/ tmp |
| 51 | * a9/ tmp |
| 52 | * a10/ tmp |
| 53 | * a11/ original length |
| 54 | */ |
| 55 | |
Chris Zankel | 173d6681 | 2006-12-10 02:18:48 -0800 | [diff] [blame] | 56 | #include <asm/variant/core.h> |
Chris Zankel | 249ac17 | 2005-06-23 22:01:20 -0700 | [diff] [blame] | 57 | |
| 58 | #ifdef __XTENSA_EB__ |
| 59 | #define ALIGN(R, W0, W1) src R, W0, W1 |
| 60 | #define SSA8(R) ssa8b R |
| 61 | #else |
| 62 | #define ALIGN(R, W0, W1) src R, W1, W0 |
| 63 | #define SSA8(R) ssa8l R |
| 64 | #endif |
| 65 | |
| 66 | /* Load or store instructions that may cause exceptions use the EX macro. */ |
| 67 | |
| 68 | #define EX(insn,reg1,reg2,offset,handler) \ |
| 69 | 9: insn reg1, reg2, offset; \ |
| 70 | .section __ex_table, "a"; \ |
| 71 | .word 9b, handler; \ |
| 72 | .previous |
| 73 | |
| 74 | |
| 75 | .text |
| 76 | .align 4 |
| 77 | .global __xtensa_copy_user |
| 78 | .type __xtensa_copy_user,@function |
| 79 | __xtensa_copy_user: |
| 80 | entry sp, 16 # minimal stack frame |
| 81 | # a2/ dst, a3/ src, a4/ len |
| 82 | mov a5, a2 # copy dst so that a2 is return value |
| 83 | mov a11, a4 # preserve original len for error case |
| 84 | .Lcommon: |
| 85 | bbsi.l a2, 0, .Ldst1mod2 # if dst is 1 mod 2 |
| 86 | bbsi.l a2, 1, .Ldst2mod4 # if dst is 2 mod 4 |
| 87 | .Ldstaligned: # return here from .Ldstunaligned when dst is aligned |
| 88 | srli a7, a4, 4 # number of loop iterations with 16B |
| 89 | # per iteration |
| 90 | movi a8, 3 # if source is also aligned, |
| 91 | bnone a3, a8, .Laligned # then use word copy |
| 92 | SSA8( a3) # set shift amount from byte offset |
| 93 | bnez a4, .Lsrcunaligned |
| 94 | movi a2, 0 # return success for len==0 |
| 95 | retw |
| 96 | |
| 97 | /* |
| 98 | * Destination is unaligned |
| 99 | */ |
| 100 | |
| 101 | .Ldst1mod2: # dst is only byte aligned |
| 102 | bltui a4, 7, .Lbytecopy # do short copies byte by byte |
| 103 | |
| 104 | # copy 1 byte |
| 105 | EX(l8ui, a6, a3, 0, l_fixup) |
| 106 | addi a3, a3, 1 |
| 107 | EX(s8i, a6, a5, 0, s_fixup) |
| 108 | addi a5, a5, 1 |
| 109 | addi a4, a4, -1 |
| 110 | bbci.l a5, 1, .Ldstaligned # if dst is now aligned, then |
| 111 | # return to main algorithm |
| 112 | .Ldst2mod4: # dst 16-bit aligned |
| 113 | # copy 2 bytes |
| 114 | bltui a4, 6, .Lbytecopy # do short copies byte by byte |
| 115 | EX(l8ui, a6, a3, 0, l_fixup) |
| 116 | EX(l8ui, a7, a3, 1, l_fixup) |
| 117 | addi a3, a3, 2 |
| 118 | EX(s8i, a6, a5, 0, s_fixup) |
| 119 | EX(s8i, a7, a5, 1, s_fixup) |
| 120 | addi a5, a5, 2 |
| 121 | addi a4, a4, -2 |
| 122 | j .Ldstaligned # dst is now aligned, return to main algorithm |
| 123 | |
| 124 | /* |
| 125 | * Byte by byte copy |
| 126 | */ |
| 127 | .align 4 |
| 128 | .byte 0 # 1 mod 4 alignment for LOOPNEZ |
| 129 | # (0 mod 4 alignment for LBEG) |
| 130 | .Lbytecopy: |
| 131 | #if XCHAL_HAVE_LOOPS |
| 132 | loopnez a4, .Lbytecopydone |
| 133 | #else /* !XCHAL_HAVE_LOOPS */ |
| 134 | beqz a4, .Lbytecopydone |
| 135 | add a7, a3, a4 # a7 = end address for source |
| 136 | #endif /* !XCHAL_HAVE_LOOPS */ |
| 137 | .Lnextbyte: |
| 138 | EX(l8ui, a6, a3, 0, l_fixup) |
| 139 | addi a3, a3, 1 |
| 140 | EX(s8i, a6, a5, 0, s_fixup) |
| 141 | addi a5, a5, 1 |
| 142 | #if !XCHAL_HAVE_LOOPS |
| 143 | blt a3, a7, .Lnextbyte |
| 144 | #endif /* !XCHAL_HAVE_LOOPS */ |
| 145 | .Lbytecopydone: |
| 146 | movi a2, 0 # return success for len bytes copied |
| 147 | retw |
| 148 | |
| 149 | /* |
| 150 | * Destination and source are word-aligned. |
| 151 | */ |
| 152 | # copy 16 bytes per iteration for word-aligned dst and word-aligned src |
| 153 | .align 4 # 1 mod 4 alignment for LOOPNEZ |
| 154 | .byte 0 # (0 mod 4 alignment for LBEG) |
| 155 | .Laligned: |
| 156 | #if XCHAL_HAVE_LOOPS |
| 157 | loopnez a7, .Loop1done |
| 158 | #else /* !XCHAL_HAVE_LOOPS */ |
| 159 | beqz a7, .Loop1done |
| 160 | slli a8, a7, 4 |
| 161 | add a8, a8, a3 # a8 = end of last 16B source chunk |
| 162 | #endif /* !XCHAL_HAVE_LOOPS */ |
| 163 | .Loop1: |
| 164 | EX(l32i, a6, a3, 0, l_fixup) |
| 165 | EX(l32i, a7, a3, 4, l_fixup) |
| 166 | EX(s32i, a6, a5, 0, s_fixup) |
| 167 | EX(l32i, a6, a3, 8, l_fixup) |
| 168 | EX(s32i, a7, a5, 4, s_fixup) |
| 169 | EX(l32i, a7, a3, 12, l_fixup) |
| 170 | EX(s32i, a6, a5, 8, s_fixup) |
| 171 | addi a3, a3, 16 |
| 172 | EX(s32i, a7, a5, 12, s_fixup) |
| 173 | addi a5, a5, 16 |
| 174 | #if !XCHAL_HAVE_LOOPS |
| 175 | blt a3, a8, .Loop1 |
| 176 | #endif /* !XCHAL_HAVE_LOOPS */ |
| 177 | .Loop1done: |
| 178 | bbci.l a4, 3, .L2 |
| 179 | # copy 8 bytes |
| 180 | EX(l32i, a6, a3, 0, l_fixup) |
| 181 | EX(l32i, a7, a3, 4, l_fixup) |
| 182 | addi a3, a3, 8 |
| 183 | EX(s32i, a6, a5, 0, s_fixup) |
| 184 | EX(s32i, a7, a5, 4, s_fixup) |
| 185 | addi a5, a5, 8 |
| 186 | .L2: |
| 187 | bbci.l a4, 2, .L3 |
| 188 | # copy 4 bytes |
| 189 | EX(l32i, a6, a3, 0, l_fixup) |
| 190 | addi a3, a3, 4 |
| 191 | EX(s32i, a6, a5, 0, s_fixup) |
| 192 | addi a5, a5, 4 |
| 193 | .L3: |
| 194 | bbci.l a4, 1, .L4 |
| 195 | # copy 2 bytes |
| 196 | EX(l16ui, a6, a3, 0, l_fixup) |
| 197 | addi a3, a3, 2 |
| 198 | EX(s16i, a6, a5, 0, s_fixup) |
| 199 | addi a5, a5, 2 |
| 200 | .L4: |
| 201 | bbci.l a4, 0, .L5 |
| 202 | # copy 1 byte |
| 203 | EX(l8ui, a6, a3, 0, l_fixup) |
| 204 | EX(s8i, a6, a5, 0, s_fixup) |
| 205 | .L5: |
| 206 | movi a2, 0 # return success for len bytes copied |
| 207 | retw |
| 208 | |
| 209 | /* |
| 210 | * Destination is aligned, Source is unaligned |
| 211 | */ |
| 212 | |
| 213 | .align 4 |
| 214 | .byte 0 # 1 mod 4 alignement for LOOPNEZ |
| 215 | # (0 mod 4 alignment for LBEG) |
| 216 | .Lsrcunaligned: |
| 217 | # copy 16 bytes per iteration for word-aligned dst and unaligned src |
| 218 | and a10, a3, a8 # save unalignment offset for below |
| 219 | sub a3, a3, a10 # align a3 (to avoid sim warnings only; not needed for hardware) |
| 220 | EX(l32i, a6, a3, 0, l_fixup) # load first word |
| 221 | #if XCHAL_HAVE_LOOPS |
| 222 | loopnez a7, .Loop2done |
| 223 | #else /* !XCHAL_HAVE_LOOPS */ |
| 224 | beqz a7, .Loop2done |
| 225 | slli a10, a7, 4 |
| 226 | add a10, a10, a3 # a10 = end of last 16B source chunk |
| 227 | #endif /* !XCHAL_HAVE_LOOPS */ |
| 228 | .Loop2: |
| 229 | EX(l32i, a7, a3, 4, l_fixup) |
| 230 | EX(l32i, a8, a3, 8, l_fixup) |
| 231 | ALIGN( a6, a6, a7) |
| 232 | EX(s32i, a6, a5, 0, s_fixup) |
| 233 | EX(l32i, a9, a3, 12, l_fixup) |
| 234 | ALIGN( a7, a7, a8) |
| 235 | EX(s32i, a7, a5, 4, s_fixup) |
| 236 | EX(l32i, a6, a3, 16, l_fixup) |
| 237 | ALIGN( a8, a8, a9) |
| 238 | EX(s32i, a8, a5, 8, s_fixup) |
| 239 | addi a3, a3, 16 |
| 240 | ALIGN( a9, a9, a6) |
| 241 | EX(s32i, a9, a5, 12, s_fixup) |
| 242 | addi a5, a5, 16 |
| 243 | #if !XCHAL_HAVE_LOOPS |
| 244 | blt a3, a10, .Loop2 |
| 245 | #endif /* !XCHAL_HAVE_LOOPS */ |
| 246 | .Loop2done: |
| 247 | bbci.l a4, 3, .L12 |
| 248 | # copy 8 bytes |
| 249 | EX(l32i, a7, a3, 4, l_fixup) |
| 250 | EX(l32i, a8, a3, 8, l_fixup) |
| 251 | ALIGN( a6, a6, a7) |
| 252 | EX(s32i, a6, a5, 0, s_fixup) |
| 253 | addi a3, a3, 8 |
| 254 | ALIGN( a7, a7, a8) |
| 255 | EX(s32i, a7, a5, 4, s_fixup) |
| 256 | addi a5, a5, 8 |
| 257 | mov a6, a8 |
| 258 | .L12: |
| 259 | bbci.l a4, 2, .L13 |
| 260 | # copy 4 bytes |
| 261 | EX(l32i, a7, a3, 4, l_fixup) |
| 262 | addi a3, a3, 4 |
| 263 | ALIGN( a6, a6, a7) |
| 264 | EX(s32i, a6, a5, 0, s_fixup) |
| 265 | addi a5, a5, 4 |
| 266 | mov a6, a7 |
| 267 | .L13: |
| 268 | add a3, a3, a10 # readjust a3 with correct misalignment |
| 269 | bbci.l a4, 1, .L14 |
| 270 | # copy 2 bytes |
| 271 | EX(l8ui, a6, a3, 0, l_fixup) |
| 272 | EX(l8ui, a7, a3, 1, l_fixup) |
| 273 | addi a3, a3, 2 |
| 274 | EX(s8i, a6, a5, 0, s_fixup) |
| 275 | EX(s8i, a7, a5, 1, s_fixup) |
| 276 | addi a5, a5, 2 |
| 277 | .L14: |
| 278 | bbci.l a4, 0, .L15 |
| 279 | # copy 1 byte |
| 280 | EX(l8ui, a6, a3, 0, l_fixup) |
| 281 | EX(s8i, a6, a5, 0, s_fixup) |
| 282 | .L15: |
| 283 | movi a2, 0 # return success for len bytes copied |
| 284 | retw |
| 285 | |
| 286 | |
| 287 | .section .fixup, "ax" |
| 288 | .align 4 |
| 289 | |
| 290 | /* a2 = original dst; a5 = current dst; a11= original len |
| 291 | * bytes_copied = a5 - a2 |
| 292 | * retval = bytes_not_copied = original len - bytes_copied |
| 293 | * retval = a11 - (a5 - a2) |
| 294 | * |
| 295 | * Clearing the remaining pieces of kernel memory plugs security |
| 296 | * holes. This functionality is the equivalent of the *_zeroing |
| 297 | * functions that some architectures provide. |
| 298 | */ |
| 299 | |
| 300 | .Lmemset: |
| 301 | .word memset |
| 302 | |
| 303 | s_fixup: |
| 304 | sub a2, a5, a2 /* a2 <-- bytes copied */ |
| 305 | sub a2, a11, a2 /* a2 <-- bytes not copied */ |
| 306 | retw |
| 307 | |
| 308 | l_fixup: |
| 309 | sub a2, a5, a2 /* a2 <-- bytes copied */ |
| 310 | sub a2, a11, a2 /* a2 <-- bytes not copied == return value */ |
| 311 | |
| 312 | /* void *memset(void *s, int c, size_t n); */ |
| 313 | mov a6, a5 /* s */ |
| 314 | movi a7, 0 /* c */ |
| 315 | mov a8, a2 /* n */ |
| 316 | l32r a4, .Lmemset |
| 317 | callx4 a4 |
| 318 | /* Ignore memset return value in a6. */ |
| 319 | /* a2 still contains bytes not copied. */ |
| 320 | retw |
| 321 | |