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   1 /*
   2  *  linux/arch/arm/lib/uaccess.S
   3  *
   4  *  Copyright (C) 1995, 1996,1997,1998 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  *  Routines to block copy data to/from user memory
  11  *   These are highly optimised both for the 4k page size
  12  *   and for various alignments.
  13  */
  14 #include <linux/linkage.h>
  15 #include <asm/assembler.h>
  16 #include <asm/errno.h>
  17
  18                 .text
  19
  20 #define PAGE_SHIFT 12
  21
  22 /* Prototype: int __arch_copy_to_user(void *to, const char *from, size_t n)
  23  * Purpose  : copy a block to user memory from kernel memory
  24  * Params   : to   - user memory
  25  *          : from - kernel memory
  26  *          : n    - number of bytes to copy
  27  * Returns  : Number of bytes NOT copied.
  28  */
  29
  30 .Lc2u_dest_not_aligned:
  31                 rsb     ip, ip, #4
  32                 cmp     ip, #2
  33                 ldrb    r3, [r1], #1
  34 USER(           strbt   r3, [r0], #1)                   @ May fault
  35                 ldrgeb  r3, [r1], #1
  36 USER(           strgebt r3, [r0], #1)                   @ May fault
  37                 ldrgtb  r3, [r1], #1
  38 USER(           strgtbt r3, [r0], #1)                   @ May fault
  39                 sub     r2, r2, ip
  40                 b       .Lc2u_dest_aligned
  41
  42 ENTRY(__arch_copy_to_user)
  43                 stmfd   sp!, {r2, r4 - r7, lr}
  44                 cmp     r2, #4
  45                 blt     .Lc2u_not_enough
  46                 ands    ip, r0, #3
  47                 bne     .Lc2u_dest_not_aligned
  48 .Lc2u_dest_aligned:
  49
  50                 ands    ip, r1, #3
  51                 bne     .Lc2u_src_not_aligned
  52 /*
  53  * Seeing as there has to be at least 8 bytes to copy, we can
  54  * copy one word, and force a user-mode page fault...
  55  */
  56
  57 .Lc2u_0fupi:    subs    r2, r2, #4
  58                 addmi   ip, r2, #4
  59                 bmi     .Lc2u_0nowords
  60                 ldr     r3, [r1], #4
  61 USER(           strt    r3, [r0], #4)                   @ May fault
  62                 mov     ip, r0, lsl #32 - PAGE_SHIFT    @ On each page, use a ld/st??t instruction
  63                 rsb     ip, ip, #0
  64                 movs    ip, ip, lsr #32 - PAGE_SHIFT
  65                 beq     .Lc2u_0fupi
  66 /*
  67  * ip = max no. of bytes to copy before needing another "strt" insn
  68  */
  69                 cmp     r2, ip
  70                 movlt   ip, r2
  71                 sub     r2, r2, ip
  72                 subs    ip, ip, #32
  73                 blt     .Lc2u_0rem8lp
  74
  75 .Lc2u_0cpy8lp:  ldmia   r1!, {r3 - r6}
  76                 stmia   r0!, {r3 - r6}                  @ Shouldnt fault
  77                 ldmia   r1!, {r3 - r6}
  78                 subs    ip, ip, #32
  79                 stmia   r0!, {r3 - r6}                  @ Shouldnt fault
  80                 bpl     .Lc2u_0cpy8lp
  81
  82 .Lc2u_0rem8lp:  cmn     ip, #16
  83                 ldmgeia r1!, {r3 - r6}
  84                 stmgeia r0!, {r3 - r6}                  @ Shouldnt fault
  85                 tst     ip, #8
  86                 ldmneia r1!, {r3 - r4}
  87                 stmneia r0!, {r3 - r4}                  @ Shouldnt fault
  88                 tst     ip, #4
  89                 ldrne   r3, [r1], #4
  90                 strnet  r3, [r0], #4                    @ Shouldnt fault
  91                 ands    ip, ip, #3
  92                 beq     .Lc2u_0fupi
  93 .Lc2u_0nowords: teq     ip, #0
  94                 beq     .Lc2u_finished
  95 .Lc2u_nowords:  cmp     ip, #2
  96                 ldrb    r3, [r1], #1
  97 USER(           strbt   r3, [r0], #1)                   @ May fault
  98                 ldrgeb  r3, [r1], #1
  99 USER(           strgebt r3, [r0], #1)                   @ May fault
 100                 ldrgtb  r3, [r1], #1
 101 USER(           strgtbt r3, [r0], #1)                   @ May fault
 102                 b       .Lc2u_finished
 103
 104 .Lc2u_not_enough:
 105                 movs    ip, r2
 106                 bne     .Lc2u_nowords
 107 .Lc2u_finished: mov     r0, #0
 108                 LOADREGS(fd,sp!,{r2, r4 - r7, pc})
 109
 110 .Lc2u_src_not_aligned:
 111                 bic     r1, r1, #3
 112                 ldr     r7, [r1], #4
 113                 cmp     ip, #2
 114                 bgt     .Lc2u_3fupi
 115                 beq     .Lc2u_2fupi
 116 .Lc2u_1fupi:    subs    r2, r2, #4
 117                 addmi   ip, r2, #4
 118                 bmi     .Lc2u_1nowords
 119                 mov     r3, r7, pull #8
 120                 ldr     r7, [r1], #4
 121                 orr     r3, r3, r7, push #24
 122 USER(           strt    r3, [r0], #4)                   @ May fault
 123                 mov     ip, r0, lsl #32 - PAGE_SHIFT
 124                 rsb     ip, ip, #0
 125                 movs    ip, ip, lsr #32 - PAGE_SHIFT
 126                 beq     .Lc2u_1fupi
 127                 cmp     r2, ip
 128                 movlt   ip, r2
 129                 sub     r2, r2, ip
 130                 subs    ip, ip, #16
 131                 blt     .Lc2u_1rem8lp
 132
 133 .Lc2u_1cpy8lp:  mov     r3, r7, pull #8
 134                 ldmia   r1!, {r4 - r7}
 135                 subs    ip, ip, #16
 136                 orr     r3, r3, r4, push #24
 137                 mov     r4, r4, pull #8
 138                 orr     r4, r4, r5, push #24
 139                 mov     r5, r5, pull #8
 140                 orr     r5, r5, r6, push #24
 141                 mov     r6, r6, pull #8
 142                 orr     r6, r6, r7, push #24
 143                 stmia   r0!, {r3 - r6}                  @ Shouldnt fault
 144                 bpl     .Lc2u_1cpy8lp
 145
 146 .Lc2u_1rem8lp:  tst     ip, #8
 147                 movne   r3, r7, pull #8
 148                 ldmneia r1!, {r4, r7}
 149                 orrne   r3, r3, r4, push #24
 150                 movne   r4, r4, pull #8
 151                 orrne   r4, r4, r7, push #24
 152                 stmneia r0!, {r3 - r4}                  @ Shouldnt fault
 153                 tst     ip, #4
 154                 movne   r3, r7, pull #8
 155                 ldrne   r7, [r1], #4
 156                 orrne   r3, r3, r7, push #24
 157                 strnet  r3, [r0], #4                    @ Shouldnt fault
 158                 ands    ip, ip, #3
 159                 beq     .Lc2u_1fupi
 160 .Lc2u_1nowords: mov     r3, r7, get_byte_1
 161                 teq     ip, #0
 162                 beq     .Lc2u_finished
 163                 cmp     ip, #2
 164 USER(           strbt   r3, [r0], #1)                   @ May fault
 165                 movge   r3, r7, get_byte_2
 166 USER(           strgebt r3, [r0], #1)                   @ May fault
 167                 movgt   r3, r7, get_byte_3
 168 USER(           strgtbt r3, [r0], #1)                   @ May fault
 169                 b       .Lc2u_finished
 170
 171 .Lc2u_2fupi:    subs    r2, r2, #4
 172                 addmi   ip, r2, #4
 173                 bmi     .Lc2u_2nowords
 174                 mov     r3, r7, pull #16
 175                 ldr     r7, [r1], #4
 176                 orr     r3, r3, r7, push #16
 177 USER(           strt    r3, [r0], #4)                   @ May fault
 178                 mov     ip, r0, lsl #32 - PAGE_SHIFT
 179                 rsb     ip, ip, #0
 180                 movs    ip, ip, lsr #32 - PAGE_SHIFT
 181                 beq     .Lc2u_2fupi
 182                 cmp     r2, ip
 183                 movlt   ip, r2
 184                 sub     r2, r2, ip
 185                 subs    ip, ip, #16
 186                 blt     .Lc2u_2rem8lp
 187
 188 .Lc2u_2cpy8lp:  mov     r3, r7, pull #16
 189                 ldmia   r1!, {r4 - r7}
 190                 subs    ip, ip, #16
 191                 orr     r3, r3, r4, push #16
 192                 mov     r4, r4, pull #16
 193                 orr     r4, r4, r5, push #16
 194                 mov     r5, r5, pull #16
 195                 orr     r5, r5, r6, push #16
 196                 mov     r6, r6, pull #16
 197                 orr     r6, r6, r7, push #16
 198                 stmia   r0!, {r3 - r6}                  @ Shouldnt fault
 199                 bpl     .Lc2u_2cpy8lp
 200
 201 .Lc2u_2rem8lp:  tst     ip, #8
 202                 movne   r3, r7, pull #16
 203                 ldmneia r1!, {r4, r7}
 204                 orrne   r3, r3, r4, push #16
 205                 movne   r4, r4, pull #16
 206                 orrne   r4, r4, r7, push #16
 207                 stmneia r0!, {r3 - r4}                  @ Shouldnt fault
 208                 tst     ip, #4
 209                 movne   r3, r7, pull #16
 210                 ldrne   r7, [r1], #4
 211                 orrne   r3, r3, r7, push #16
 212                 strnet  r3, [r0], #4                    @ Shouldnt fault
 213                 ands    ip, ip, #3
 214                 beq     .Lc2u_2fupi
 215 .Lc2u_2nowords: mov     r3, r7, get_byte_2
 216                 teq     ip, #0
 217                 beq     .Lc2u_finished
 218                 cmp     ip, #2
 219 USER(           strbt   r3, [r0], #1)                   @ May fault
 220                 movge   r3, r7, get_byte_3
 221 USER(           strgebt r3, [r0], #1)                   @ May fault
 222                 ldrgtb  r3, [r1], #0
 223 USER(           strgtbt r3, [r0], #1)                   @ May fault
 224                 b       .Lc2u_finished
 225
 226 .Lc2u_3fupi:    subs    r2, r2, #4
 227                 addmi   ip, r2, #4
 228                 bmi     .Lc2u_3nowords
 229                 mov     r3, r7, pull #24
 230                 ldr     r7, [r1], #4
 231                 orr     r3, r3, r7, push #8
 232 USER(           strt    r3, [r0], #4)                   @ May fault
 233                 mov     ip, r0, lsl #32 - PAGE_SHIFT
 234                 rsb     ip, ip, #0
 235                 movs    ip, ip, lsr #32 - PAGE_SHIFT
 236                 beq     .Lc2u_3fupi
 237                 cmp     r2, ip
 238                 movlt   ip, r2
 239                 sub     r2, r2, ip
 240                 subs    ip, ip, #16
 241                 blt     .Lc2u_3rem8lp
 242
 243 .Lc2u_3cpy8lp:  mov     r3, r7, pull #24
 244                 ldmia   r1!, {r4 - r7}
 245                 subs    ip, ip, #16
 246                 orr     r3, r3, r4, push #8
 247                 mov     r4, r4, pull #24
 248                 orr     r4, r4, r5, push #8
 249                 mov     r5, r5, pull #24
 250                 orr     r5, r5, r6, push #8
 251                 mov     r6, r6, pull #24
 252                 orr     r6, r6, r7, push #8
 253                 stmia   r0!, {r3 - r6}                  @ Shouldnt fault
 254                 bpl     .Lc2u_3cpy8lp
 255
 256 .Lc2u_3rem8lp:  tst     ip, #8
 257                 movne   r3, r7, pull #24
 258                 ldmneia r1!, {r4, r7}
 259                 orrne   r3, r3, r4, push #8
 260                 movne   r4, r4, pull #24
 261                 orrne   r4, r4, r7, push #8
 262                 stmneia r0!, {r3 - r4}                  @ Shouldnt fault
 263                 tst     ip, #4
 264                 movne   r3, r7, pull #24
 265                 ldrne   r7, [r1], #4
 266                 orrne   r3, r3, r7, push #8
 267                 strnet  r3, [r0], #4                    @ Shouldnt fault
 268                 ands    ip, ip, #3
 269                 beq     .Lc2u_3fupi
 270 .Lc2u_3nowords: mov     r3, r7, get_byte_3
 271                 teq     ip, #0
 272                 beq     .Lc2u_finished
 273                 cmp     ip, #2
 274 USER(           strbt   r3, [r0], #1)                   @ May fault
 275                 ldrgeb  r3, [r1], #1
 276 USER(           strgebt r3, [r0], #1)                   @ May fault
 277                 ldrgtb  r3, [r1], #0
 278 USER(           strgtbt r3, [r0], #1)                   @ May fault
 279                 b       .Lc2u_finished
 280
 281                 .section .fixup,"ax"
 282                 .align  0
 283 9001:           LOADREGS(fd,sp!, {r0, r4 - r7, pc})
 284                 .previous
 285
 286 /* Prototype: unsigned long __arch_copy_from_user(void *to,const void *from,unsigned long n);
 287  * Purpose  : copy a block from user memory to kernel memory
 288  * Params   : to   - kernel memory
 289  *          : from - user memory
 290  *          : n    - number of bytes to copy
 291  * Returns  : Number of bytes NOT copied.
 292  */
 293 .Lcfu_dest_not_aligned:
 294                 rsb     ip, ip, #4
 295                 cmp     ip, #2
 296 USER(           ldrbt   r3, [r1], #1)                   @ May fault
 297                 strb    r3, [r0], #1
 298 USER(           ldrgebt r3, [r1], #1)                   @ May fault
 299                 strgeb  r3, [r0], #1
 300 USER(           ldrgtbt r3, [r1], #1)                   @ May fault
 301                 strgtb  r3, [r0], #1
 302                 sub     r2, r2, ip
 303                 b       .Lcfu_dest_aligned
 304
 305 ENTRY(__arch_copy_from_user)
 306                 stmfd   sp!, {r0, r2, r4 - r7, lr}
 307                 cmp     r2, #4
 308                 blt     .Lcfu_not_enough
 309                 ands    ip, r0, #3
 310                 bne     .Lcfu_dest_not_aligned
 311 .Lcfu_dest_aligned:
 312                 ands    ip, r1, #3
 313                 bne     .Lcfu_src_not_aligned
 314
 315 /*
 316  * Seeing as there has to be at least 8 bytes to copy, we can
 317  * copy one word, and force a user-mode page fault...
 318  */
 319
 320 .Lcfu_0fupi:    subs    r2, r2, #4
 321                 addmi   ip, r2, #4
 322                 bmi     .Lcfu_0nowords
 323 USER(           ldrt    r3, [r1], #4)
 324                 str     r3, [r0], #4
 325                 mov     ip, r1, lsl #32 - PAGE_SHIFT    @ On each page, use a ld/st??t instruction
 326                 rsb     ip, ip, #0
 327                 movs    ip, ip, lsr #32 - PAGE_SHIFT
 328                 beq     .Lcfu_0fupi
 329 /*
 330  * ip = max no. of bytes to copy before needing another "strt" insn
 331  */
 332                 cmp     r2, ip
 333                 movlt   ip, r2
 334                 sub     r2, r2, ip
 335                 subs    ip, ip, #32
 336                 blt     .Lcfu_0rem8lp
 337
 338 .Lcfu_0cpy8lp:  ldmia   r1!, {r3 - r6}                  @ Shouldnt fault
 339                 stmia   r0!, {r3 - r6}
 340                 ldmia   r1!, {r3 - r6}                  @ Shouldnt fault
 341                 subs    ip, ip, #32
 342                 stmia   r0!, {r3 - r6}
 343                 bpl     .Lcfu_0cpy8lp
 344
 345 .Lcfu_0rem8lp:  cmn     ip, #16
 346                 ldmgeia r1!, {r3 - r6}                  @ Shouldnt fault
 347                 stmgeia r0!, {r3 - r6}
 348                 tst     ip, #8
 349                 ldmneia r1!, {r3 - r4}                  @ Shouldnt fault
 350                 stmneia r0!, {r3 - r4}
 351                 tst     ip, #4
 352                 ldrnet  r3, [r1], #4                    @ Shouldnt fault
 353                 strne   r3, [r0], #4
 354                 ands    ip, ip, #3
 355                 beq     .Lcfu_0fupi
 356 .Lcfu_0nowords: teq     ip, #0
 357                 beq     .Lcfu_finished
 358 .Lcfu_nowords:  cmp     ip, #2
 359 USER(           ldrbt   r3, [r1], #1)                   @ May fault
 360                 strb    r3, [r0], #1
 361 USER(           ldrgebt r3, [r1], #1)                   @ May fault
 362                 strgeb  r3, [r0], #1
 363 USER(           ldrgtbt r3, [r1], #1)                   @ May fault
 364                 strgtb  r3, [r0], #1
 365                 b       .Lcfu_finished
 366
 367 .Lcfu_not_enough:
 368                 movs    ip, r2
 369                 bne     .Lcfu_nowords
 370 .Lcfu_finished: mov     r0, #0
 371                 add     sp, sp, #8
 372                 LOADREGS(fd,sp!,{r4 - r7, pc})
 373
 374 .Lcfu_src_not_aligned:
 375                 bic     r1, r1, #3
 376 USER(           ldrt    r7, [r1], #4)                   @ May fault
 377                 cmp     ip, #2
 378                 bgt     .Lcfu_3fupi
 379                 beq     .Lcfu_2fupi
 380 .Lcfu_1fupi:    subs    r2, r2, #4
 381                 addmi   ip, r2, #4
 382                 bmi     .Lcfu_1nowords
 383                 mov     r3, r7, pull #8
 384 USER(           ldrt    r7, [r1], #4)                   @ May fault
 385                 orr     r3, r3, r7, push #24
 386                 str     r3, [r0], #4
 387                 mov     ip, r1, lsl #32 - PAGE_SHIFT
 388                 rsb     ip, ip, #0
 389                 movs    ip, ip, lsr #32 - PAGE_SHIFT
 390                 beq     .Lcfu_1fupi
 391                 cmp     r2, ip
 392                 movlt   ip, r2
 393                 sub     r2, r2, ip
 394                 subs    ip, ip, #16
 395                 blt     .Lcfu_1rem8lp
 396
 397 .Lcfu_1cpy8lp:  mov     r3, r7, pull #8
 398                 ldmia   r1!, {r4 - r7}                  @ Shouldnt fault
 399                 subs    ip, ip, #16
 400                 orr     r3, r3, r4, push #24
 401                 mov     r4, r4, pull #8
 402                 orr     r4, r4, r5, push #24
 403                 mov     r5, r5, pull #8
 404                 orr     r5, r5, r6, push #24
 405                 mov     r6, r6, pull #8
 406                 orr     r6, r6, r7, push #24
 407                 stmia   r0!, {r3 - r6}
 408                 bpl     .Lcfu_1cpy8lp
 409
 410 .Lcfu_1rem8lp:  tst     ip, #8
 411                 movne   r3, r7, pull #8
 412                 ldmneia r1!, {r4, r7}                   @ Shouldnt fault
 413                 orrne   r3, r3, r4, push #24
 414                 movne   r4, r4, pull #8
 415                 orrne   r4, r4, r7, push #24
 416                 stmneia r0!, {r3 - r4}
 417                 tst     ip, #4
 418                 movne   r3, r7, pull #8
 419 USER(           ldrnet  r7, [r1], #4)                   @ May fault
 420                 orrne   r3, r3, r7, push #24
 421                 strne   r3, [r0], #4
 422                 ands    ip, ip, #3
 423                 beq     .Lcfu_1fupi
 424 .Lcfu_1nowords: mov     r3, r7, get_byte_1
 425                 teq     ip, #0
 426                 beq     .Lcfu_finished
 427                 cmp     ip, #2
 428                 strb    r3, [r0], #1
 429                 movge   r3, r7, get_byte_2
 430                 strgeb  r3, [r0], #1
 431                 movgt   r3, r7, get_byte_3
 432                 strgtb  r3, [r0], #1
 433                 b       .Lcfu_finished
 434
 435 .Lcfu_2fupi:    subs    r2, r2, #4
 436                 addmi   ip, r2, #4
 437                 bmi     .Lcfu_2nowords
 438                 mov     r3, r7, pull #16
 439 USER(           ldrt    r7, [r1], #4)                   @ May fault
 440                 orr     r3, r3, r7, push #16
 441                 str     r3, [r0], #4
 442                 mov     ip, r1, lsl #32 - PAGE_SHIFT
 443                 rsb     ip, ip, #0
 444                 movs    ip, ip, lsr #32 - PAGE_SHIFT
 445                 beq     .Lcfu_2fupi
 446                 cmp     r2, ip
 447                 movlt   ip, r2
 448                 sub     r2, r2, ip
 449                 subs    ip, ip, #16
 450                 blt     .Lcfu_2rem8lp
 451
 452
 453 .Lcfu_2cpy8lp:  mov     r3, r7, pull #16
 454                 ldmia   r1!, {r4 - r7}                  @ Shouldnt fault
 455                 subs    ip, ip, #16
 456                 orr     r3, r3, r4, push #16
 457                 mov     r4, r4, pull #16
 458                 orr     r4, r4, r5, push #16
 459                 mov     r5, r5, pull #16
 460                 orr     r5, r5, r6, push #16
 461                 mov     r6, r6, pull #16
 462                 orr     r6, r6, r7, push #16
 463                 stmia   r0!, {r3 - r6}
 464                 bpl     .Lcfu_2cpy8lp
 465
 466 .Lcfu_2rem8lp:  tst     ip, #8
 467                 movne   r3, r7, pull #16
 468                 ldmneia r1!, {r4, r7}                   @ Shouldnt fault
 469                 orrne   r3, r3, r4, push #16
 470                 movne   r4, r4, pull #16
 471                 orrne   r4, r4, r7, push #16
 472                 stmneia r0!, {r3 - r4}
 473                 tst     ip, #4
 474                 movne   r3, r7, pull #16
 475 USER(           ldrnet  r7, [r1], #4)                   @ May fault
 476                 orrne   r3, r3, r7, push #16
 477                 strne   r3, [r0], #4
 478                 ands    ip, ip, #3
 479                 beq     .Lcfu_2fupi
 480 .Lcfu_2nowords: mov     r3, r7, get_byte_2
 481                 teq     ip, #0
 482                 beq     .Lcfu_finished
 483                 cmp     ip, #2
 484                 strb    r3, [r0], #1
 485                 movge   r3, r7, get_byte_3
 486                 strgeb  r3, [r0], #1
 487 USER(           ldrgtbt r3, [r1], #0)                   @ May fault
 488                 strgtb  r3, [r0], #1
 489                 b       .Lcfu_finished
 490
 491 .Lcfu_3fupi:    subs    r2, r2, #4
 492                 addmi   ip, r2, #4
 493                 bmi     .Lcfu_3nowords
 494                 mov     r3, r7, pull #24
 495 USER(           ldrt    r7, [r1], #4)                   @ May fault
 496                 orr     r3, r3, r7, push #8
 497                 str     r3, [r0], #4
 498                 mov     ip, r1, lsl #32 - PAGE_SHIFT
 499                 rsb     ip, ip, #0
 500                 movs    ip, ip, lsr #32 - PAGE_SHIFT
 501                 beq     .Lcfu_3fupi
 502                 cmp     r2, ip
 503                 movlt   ip, r2
 504                 sub     r2, r2, ip
 505                 subs    ip, ip, #16
 506                 blt     .Lcfu_3rem8lp
 507
 508 .Lcfu_3cpy8lp:  mov     r3, r7, pull #24
 509                 ldmia   r1!, {r4 - r7}                  @ Shouldnt fault
 510                 orr     r3, r3, r4, push #8
 511                 mov     r4, r4, pull #24
 512                 orr     r4, r4, r5, push #8
 513                 mov     r5, r5, pull #24
 514                 orr     r5, r5, r6, push #8
 515                 mov     r6, r6, pull #24
 516                 orr     r6, r6, r7, push #8
 517                 stmia   r0!, {r3 - r6}
 518                 subs    ip, ip, #16
 519                 bpl     .Lcfu_3cpy8lp
 520
 521 .Lcfu_3rem8lp:  tst     ip, #8
 522                 movne   r3, r7, pull #24
 523                 ldmneia r1!, {r4, r7}                   @ Shouldnt fault
 524                 orrne   r3, r3, r4, push #8
 525                 movne   r4, r4, pull #24
 526                 orrne   r4, r4, r7, push #8
 527                 stmneia r0!, {r3 - r4}
 528                 tst     ip, #4
 529                 movne   r3, r7, pull #24
 530 USER(           ldrnet  r7, [r1], #4)                   @ May fault
 531                 orrne   r3, r3, r7, push #8
 532                 strne   r3, [r0], #4
 533                 ands    ip, ip, #3
 534                 beq     .Lcfu_3fupi
 535 .Lcfu_3nowords: mov     r3, r7, get_byte_3
 536                 teq     ip, #0
 537                 beq     .Lcfu_finished
 538                 cmp     ip, #2
 539                 strb    r3, [r0], #1
 540 USER(           ldrgebt r3, [r1], #1)                   @ May fault
 541                 strgeb  r3, [r0], #1
 542 USER(           ldrgtbt r3, [r1], #1)                   @ May fault
 543                 strgtb  r3, [r0], #1
 544                 b       .Lcfu_finished
 545
 546                 .section .fixup,"ax"
 547                 .align  0
 548                 /*
 549                  * We took an exception.  r0 contains a pointer to
 550                  * the byte not copied.
 551                  */
 552 9001:           ldr     r2, [sp], #4                    @ void *to
 553                 sub     r2, r0, r2                      @ bytes copied
 554                 ldr     r1, [sp], #4                    @ unsigned long count
 555                 subs    r4, r1, r2                      @ bytes left to copy
 556                 movne   r1, r4
 557                 blne    __memzero
 558                 mov     r0, r4
 559                 LOADREGS(fd,sp!, {r4 - r7, pc})
 560                 .previous
 561