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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 | /* * linux/arch/arm/lib/uaccess.S * * Copyright (C) 1995, 1996,1997,1998 Russell King * * Routines to block copy data to/from user memory * These are highly optimised both for the 4k page size * and for various alignments. */ #include <linux/linkage.h> #include <asm/assembler.h> #include <asm/errno.h> .text #define USER(x...) \ 9999: x; \ .section __ex_table,"a"; \ .align 3; \ .long 9999b,9001f; \ .previous #define PAGE_SHIFT 12 /* Prototype: int __arch_copy_to_user(void *to, const char *from, size_t n) * Purpose : copy a block to user memory from kernel memory * Params : to - user memory * : from - kernel memory * : n - number of bytes to copy * Returns : Number of bytes NOT copied. */ .c2u_dest_not_aligned: rsb ip, ip, #4 cmp ip, #2 ldrb r3, [r1], #1 USER( strbt r3, [r0], #1) @ May fault ldrgeb r3, [r1], #1 USER( strgebt r3, [r0], #1) @ May fault ldrgtb r3, [r1], #1 USER( strgtbt r3, [r0], #1) @ May fault sub r2, r2, ip b .c2u_dest_aligned ENTRY(__arch_copy_to_user) stmfd sp!, {r2, r4 - r7, lr} cmp r2, #4 blt .c2u_not_enough ands ip, r0, #3 bne .c2u_dest_not_aligned .c2u_dest_aligned: ands ip, r1, #3 bne .c2u_src_not_aligned /* * Seeing as there has to be at least 8 bytes to copy, we can * copy one word, and force a user-mode page fault... */ .c2u_0fupi: subs r2, r2, #4 addmi ip, r2, #4 bmi .c2u_0nowords ldr r3, [r1], #4 USER( strt r3, [r0], #4) @ May fault mov ip, r0, lsl #32 - PAGE_SHIFT @ On each page, use a ld/st??t instruction rsb ip, ip, #0 movs ip, ip, lsr #32 - PAGE_SHIFT beq .c2u_0fupi /* * ip = max no. of bytes to copy before needing another "strt" insn */ cmp r2, ip movlt ip, r2 sub r2, r2, ip subs ip, ip, #32 blt .c2u_0rem8lp .c2u_0cpy8lp: ldmia r1!, {r3 - r6} stmia r0!, {r3 - r6} @ Shouldn't fault ldmia r1!, {r3 - r6} stmia r0!, {r3 - r6} @ Shouldn't fault subs ip, ip, #32 bpl .c2u_0cpy8lp .c2u_0rem8lp: cmn ip, #16 ldmgeia r1!, {r3 - r6} stmgeia r0!, {r3 - r6} @ Shouldn't fault tst ip, #8 ldmneia r1!, {r3 - r4} stmneia r0!, {r3 - r4} @ Shouldn't fault tst ip, #4 ldrne r3, [r1], #4 strnet r3, [r0], #4 @ Shouldn't fault ands ip, ip, #3 beq .c2u_0fupi .c2u_0nowords: teq ip, #0 beq .c2u_finished .c2u_nowords: cmp ip, #2 ldrb r3, [r1], #1 USER( strbt r3, [r0], #1) @ May fault ldrgeb r3, [r1], #1 USER( strgebt r3, [r0], #1) @ May fault ldrgtb r3, [r1], #1 USER( strgtbt r3, [r0], #1) @ May fault b .c2u_finished .c2u_not_enough: movs ip, r2 bne .c2u_nowords .c2u_finished: mov r0, #0 LOADREGS(fd,sp!,{r2, r4 - r7, pc}) .c2u_src_not_aligned: bic r1, r1, #3 ldr r7, [r1], #4 cmp ip, #2 bgt .c2u_3fupi beq .c2u_2fupi .c2u_1fupi: subs r2, r2, #4 addmi ip, r2, #4 bmi .c2u_1nowords mov r3, r7, lsr #8 ldr r7, [r1], #4 orr r3, r3, r7, lsl #24 USER( strt r3, [r0], #4) @ May fault mov ip, r0, lsl #32 - PAGE_SHIFT rsb ip, ip, #0 movs ip, ip, lsr #32 - PAGE_SHIFT beq .c2u_1fupi cmp r2, ip movlt ip, r2 sub r2, r2, ip subs ip, ip, #16 blt .c2u_1rem8lp .c2u_1cpy8lp: mov r3, r7, lsr #8 ldmia r1!, {r4 - r7} orr r3, r3, r4, lsl #24 mov r4, r4, lsr #8 orr r4, r4, r5, lsl #24 mov r5, r5, lsr #8 orr r5, r5, r6, lsl #24 mov r6, r6, lsr #8 orr r6, r6, r7, lsl #24 stmia r0!, {r3 - r6} @ Shouldn't fault subs ip, ip, #16 bpl .c2u_1cpy8lp .c2u_1rem8lp: tst ip, #8 movne r3, r7, lsr #8 ldmneia r1!, {r4, r7} orrne r3, r3, r4, lsl #24 movne r4, r4, lsr #8 orrne r4, r4, r7, lsl #24 stmneia r0!, {r3 - r4} @ Shouldn't fault tst ip, #4 movne r3, r7, lsr #8 ldrne r7, [r1], #4 orrne r3, r3, r7, lsl #24 strnet r3, [r0], #4 @ Shouldn't fault ands ip, ip, #3 beq .c2u_1fupi .c2u_1nowords: mov r3, r7, lsr #8 teq ip, #0 beq .c2u_finished cmp ip, #2 USER( strbt r3, [r0], #1) @ May fault movge r3, r3, lsr #8 USER( strgebt r3, [r0], #1) @ May fault movgt r3, r3, lsr #8 USER( strgtbt r3, [r0], #1) @ May fault b .c2u_finished .c2u_2fupi: subs r2, r2, #4 addmi ip, r2, #4 bmi .c2u_2nowords mov r3, r7, lsr #16 ldr r7, [r1], #4 orr r3, r3, r7, lsl #16 USER( strt r3, [r0], #4) @ May fault mov ip, r0, lsl #32 - PAGE_SHIFT rsb ip, ip, #0 movs ip, ip, lsr #32 - PAGE_SHIFT beq .c2u_2fupi cmp r2, ip movlt ip, r2 sub r2, r2, ip subs ip, ip, #16 blt .c2u_2rem8lp .c2u_2cpy8lp: mov r3, r7, lsr #16 ldmia r1!, {r4 - r7} orr r3, r3, r4, lsl #16 mov r4, r4, lsr #16 orr r4, r4, r5, lsl #16 mov r5, r5, lsr #16 orr r5, r5, r6, lsl #16 mov r6, r6, lsr #16 orr r6, r6, r7, lsl #16 stmia r0!, {r3 - r6} @ Shouldn't fault subs ip, ip, #16 bpl .c2u_2cpy8lp .c2u_2rem8lp: tst ip, #8 movne r3, r7, lsr #16 ldmneia r1!, {r4, r7} orrne r3, r3, r4, lsl #16 movne r4, r4, lsr #16 orrne r4, r4, r7, lsl #16 stmneia r0!, {r3 - r4} @ Shouldn't fault tst ip, #4 movne r3, r7, lsr #16 ldrne r7, [r1], #4 orrne r3, r3, r7, lsl #16 strnet r3, [r0], #4 @ Shouldn't fault ands ip, ip, #3 beq .c2u_2fupi .c2u_2nowords: mov r3, r7, lsr #16 teq ip, #0 beq .c2u_finished cmp ip, #2 USER( strbt r3, [r0], #1) @ May fault movge r3, r3, lsr #8 USER( strgebt r3, [r0], #1) @ May fault ldrgtb r3, [r1], #0 USER( strgtbt r3, [r0], #1) @ May fault b .c2u_finished .c2u_3fupi: subs r2, r2, #4 addmi ip, r2, #4 bmi .c2u_3nowords mov r3, r7, lsr #24 ldr r7, [r1], #4 orr r3, r3, r7, lsl #8 USER( strt r3, [r0], #4) @ May fault mov ip, r0, lsl #32 - PAGE_SHIFT rsb ip, ip, #0 movs ip, ip, lsr #32 - PAGE_SHIFT beq .c2u_3fupi cmp r2, ip movlt ip, r2 sub r2, r2, ip subs ip, ip, #16 blt .c2u_3rem8lp .c2u_3cpy8lp: mov r3, r7, lsr #24 ldmia r1!, {r4 - r7} orr r3, r3, r4, lsl #8 mov r4, r4, lsr #24 orr r4, r4, r5, lsl #8 mov r5, r5, lsr #24 orr r5, r5, r6, lsl #8 mov r6, r6, lsr #24 orr r6, r6, r7, lsl #8 stmia r0!, {r3 - r6} @ Shouldn't fault subs ip, ip, #16 bpl .c2u_3cpy8lp .c2u_3rem8lp: tst ip, #8 movne r3, r7, lsr #24 ldmneia r1!, {r4, r7} orrne r3, r3, r4, lsl #8 movne r4, r4, lsr #24 orrne r4, r4, r7, lsl #8 stmneia r0!, {r3 - r4} @ Shouldn't fault tst ip, #4 movne r3, r7, lsr #24 ldrne r7, [r1], #4 orrne r3, r3, r7, lsl #8 strnet r3, [r0], #4 @ Shouldn't fault ands ip, ip, #3 beq .c2u_3fupi .c2u_3nowords: mov r3, r7, lsr #24 teq ip, #0 beq .c2u_finished cmp ip, #2 USER( strbt r3, [r0], #1) @ May fault ldrge r3, [r1], #0 USER( strgebt r3, [r0], #1) @ May fault movgt r3, r3, lsr #8 USER( strgtbt r3, [r0], #1) @ May fault b .c2u_finished .section .fixup,"ax" .align 0 9001: LOADREGS(fd,sp!, {r0, r4 - r7, pc}) .previous /* Prototype: unsigned long __arch_copy_from_user(void *to,const void *from,unsigned long n); * Purpose : copy a block from user memory to kernel memory * Params : to - kernel memory * : from - user memory * : n - number of bytes to copy * Returns : Number of bytes NOT copied. */ .cfu_dest_not_aligned: rsb ip, ip, #4 cmp ip, #2 USER( ldrbt r3, [r1], #1) @ May fault strb r3, [r0], #1 USER( ldrgebt r3, [r1], #1) @ May fault strgeb r3, [r0], #1 USER( ldrgtbt r3, [r1], #1) @ May fault strgtb r3, [r0], #1 sub r2, r2, ip b .cfu_dest_aligned ENTRY(__arch_copy_from_user) stmfd sp!, {r0, r2, r4 - r7, lr} cmp r2, #4 blt .cfu_not_enough ands ip, r0, #3 bne .cfu_dest_not_aligned .cfu_dest_aligned: ands ip, r1, #3 bne .cfu_src_not_aligned /* * Seeing as there has to be at least 8 bytes to copy, we can * copy one word, and force a user-mode page fault... */ .cfu_0fupi: subs r2, r2, #4 addmi ip, r2, #4 bmi .cfu_0nowords USER( ldrt r3, [r1], #4) str r3, [r0], #4 mov ip, r1, lsl #32 - PAGE_SHIFT @ On each page, use a ld/st??t instruction rsb ip, ip, #0 movs ip, ip, lsr #32 - PAGE_SHIFT beq .cfu_0fupi /* * ip = max no. of bytes to copy before needing another "strt" insn */ cmp r2, ip movlt ip, r2 sub r2, r2, ip subs ip, ip, #32 blt .cfu_0rem8lp .cfu_0cpy8lp: ldmia r1!, {r3 - r6} @ Shouldn't fault stmia r0!, {r3 - r6} ldmia r1!, {r3 - r6} @ Shouldn't fault stmia r0!, {r3 - r6} subs ip, ip, #32 bpl .cfu_0cpy8lp .cfu_0rem8lp: cmn ip, #16 ldmgeia r1!, {r3 - r6} @ Shouldn't fault stmgeia r0!, {r3 - r6} tst ip, #8 ldmneia r1!, {r3 - r4} @ Shouldn't fault stmneia r0!, {r3 - r4} tst ip, #4 ldrnet r3, [r1], #4 @ Shouldn't fault strne r3, [r0], #4 ands ip, ip, #3 beq .cfu_0fupi .cfu_0nowords: teq ip, #0 beq .cfu_finished .cfu_nowords: cmp ip, #2 USER( ldrbt r3, [r1], #1) @ May fault strb r3, [r0], #1 USER( ldrgebt r3, [r1], #1) @ May fault strgeb r3, [r0], #1 USER( ldrgtbt r3, [r1], #1) @ May fault strgtb r3, [r0], #1 b .cfu_finished .cfu_not_enough: movs ip, r2 bne .cfu_nowords .cfu_finished: mov r0, #0 add sp, sp, #8 LOADREGS(fd,sp!,{r4 - r7, pc}) .cfu_src_not_aligned: bic r1, r1, #3 USER( ldrt r7, [r1], #4) @ May fault cmp ip, #2 bgt .cfu_3fupi beq .cfu_2fupi .cfu_1fupi: subs r2, r2, #4 addmi ip, r2, #4 bmi .cfu_1nowords mov r3, r7, lsr #8 USER( ldrt r7, [r1], #4) @ May fault orr r3, r3, r7, lsl #24 str r3, [r0], #4 mov ip, r1, lsl #32 - PAGE_SHIFT rsb ip, ip, #0 movs ip, ip, lsr #32 - PAGE_SHIFT beq .cfu_1fupi cmp r2, ip movlt ip, r2 sub r2, r2, ip subs ip, ip, #16 blt .cfu_1rem8lp .cfu_1cpy8lp: mov r3, r7, lsr #8 ldmia r1!, {r4 - r7} @ Shouldn't fault orr r3, r3, r4, lsl #24 mov r4, r4, lsr #8 orr r4, r4, r5, lsl #24 mov r5, r5, lsr #8 orr r5, r5, r6, lsl #24 mov r6, r6, lsr #8 orr r6, r6, r7, lsl #24 stmia r0!, {r3 - r6} subs ip, ip, #16 bpl .cfu_1cpy8lp .cfu_1rem8lp: tst ip, #8 movne r3, r7, lsr #8 ldmneia r1!, {r4, r7} @ Shouldn't fault orrne r3, r3, r4, lsl #24 movne r4, r4, lsr #8 orrne r4, r4, r7, lsl #24 stmneia r0!, {r3 - r4} tst ip, #4 movne r3, r7, lsr #8 USER( ldrnet r7, [r1], #4) @ May fault orrne r3, r3, r7, lsl #24 strne r3, [r0], #4 ands ip, ip, #3 beq .cfu_1fupi .cfu_1nowords: mov r3, r7, lsr #8 teq ip, #0 beq .cfu_finished cmp ip, #2 strb r3, [r0], #1 movge r3, r3, lsr #8 strgeb r3, [r0], #1 movgt r3, r3, lsr #8 strgtb r3, [r0], #1 b .cfu_finished .cfu_2fupi: subs r2, r2, #4 addmi ip, r2, #4 bmi .cfu_2nowords mov r3, r7, lsr #16 USER( ldrt r7, [r1], #4) @ May fault orr r3, r3, r7, lsl #16 str r3, [r0], #4 mov ip, r1, lsl #32 - PAGE_SHIFT rsb ip, ip, #0 movs ip, ip, lsr #32 - PAGE_SHIFT beq .cfu_2fupi cmp r2, ip movlt ip, r2 sub r2, r2, ip subs ip, ip, #16 blt .cfu_2rem8lp .cfu_2cpy8lp: mov r3, r7, lsr #16 ldmia r1!, {r4 - r7} @ Shouldn't fault orr r3, r3, r4, lsl #16 mov r4, r4, lsr #16 orr r4, r4, r5, lsl #16 mov r5, r5, lsr #16 orr r5, r5, r6, lsl #16 mov r6, r6, lsr #16 orr r6, r6, r7, lsl #16 stmia r0!, {r3 - r6} subs ip, ip, #16 bpl .cfu_2cpy8lp .cfu_2rem8lp: tst ip, #8 movne r3, r7, lsr #16 ldmneia r1!, {r4, r7} @ Shouldn't fault orrne r3, r3, r4, lsl #16 movne r4, r4, lsr #16 orrne r4, r4, r7, lsl #16 stmneia r0!, {r3 - r4} tst ip, #4 movne r3, r7, lsr #16 USER( ldrnet r7, [r1], #4) @ May fault orrne r3, r3, r7, lsl #16 strne r3, [r0], #4 ands ip, ip, #3 beq .cfu_2fupi .cfu_2nowords: mov r3, r7, lsr #16 teq ip, #0 beq .cfu_finished cmp ip, #2 strb r3, [r0], #1 movge r3, r3, lsr #8 strgeb r3, [r0], #1 USER( ldrgtbt r3, [r1], #0) @ May fault strgtb r3, [r0], #1 b .cfu_finished .cfu_3fupi: subs r2, r2, #4 addmi ip, r2, #4 bmi .cfu_3nowords mov r3, r7, lsr #24 USER( ldrt r7, [r1], #4) @ May fault orr r3, r3, r7, lsl #8 str r3, [r0], #4 mov ip, r1, lsl #32 - PAGE_SHIFT rsb ip, ip, #0 movs ip, ip, lsr #32 - PAGE_SHIFT beq .cfu_3fupi cmp r2, ip movlt ip, r2 sub r2, r2, ip subs ip, ip, #16 blt .cfu_3rem8lp .cfu_3cpy8lp: mov r3, r7, lsr #24 ldmia r1!, {r4 - r7} @ Shouldn't fault orr r3, r3, r4, lsl #8 mov r4, r4, lsr #24 orr r4, r4, r5, lsl #8 mov r5, r5, lsr #24 orr r5, r5, r6, lsl #8 mov r6, r6, lsr #24 orr r6, r6, r7, lsl #8 stmia r0!, {r3 - r6} subs ip, ip, #16 bpl .cfu_3cpy8lp .cfu_3rem8lp: tst ip, #8 movne r3, r7, lsr #24 ldmneia r1!, {r4, r7} @ Shouldn't fault orrne r3, r3, r4, lsl #8 movne r4, r4, lsr #24 orrne r4, r4, r7, lsl #8 stmneia r0!, {r3 - r4} tst ip, #4 movne r3, r7, lsr #24 USER( ldrnet r7, [r1], #4) @ May fault orrne r3, r3, r7, lsl #8 strne r3, [r0], #4 ands ip, ip, #3 beq .cfu_3fupi .cfu_3nowords: mov r3, r7, lsr #24 teq ip, #0 beq .cfu_finished cmp ip, #2 strb r3, [r0], #1 USER( ldrget r3, [r1], #0) @ May fault strgeb r3, [r0], #1 movgt r3, r3, lsr #8 strgtb r3, [r0], #1 b .cfu_finished .section .fixup,"ax" .align 0 /* We took an exception. Zero out the buffer and pretend no data was copied. */ 9001: ldr r0, [sp], #4 ldr r1, [sp] teq r1, #0 blne SYMBOL_NAME(__memzero) LOADREGS(fd,sp!, {r0, r4 - r7, pc}) .previous /* Prototype: int __arch_clear_user(void *addr, size_t sz) * Purpose : clear some user memory * Params : addr - user memory address to clear * : sz - number of bytes to clear * Returns : number of bytes NOT cleared */ ENTRY(__arch_clear_user) stmfd sp!, {r1, lr} mov r2, #0 cmp r1, #4 blt 2f ands ip, r0, #3 beq 1f cmp ip, #2 USER( strbt r2, [r0], #1) USER( strlebt r2, [r0], #1) USER( strltbt r2, [r0], #1) rsb ip, ip, #4 sub r1, r1, ip @ 7 6 5 4 3 2 1 1: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7 USER( strplt r2, [r0], #4) USER( strplt r2, [r0], #4) bpl 1b adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3 USER( strplt r2, [r0], #4) 2: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x USER( strnebt r2, [r0], #1) USER( strnebt r2, [r0], #1) tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1 USER( strnebt r2, [r0], #1) mov r0, #0 LOADREGS(fd,sp!, {r1, pc}) .section .fixup,"ax" .align 0 9001: LOADREGS(fd,sp!, {r0, pc}) .previous /* Prototype: unsigned long __arch_strnlen_user(const char *str, long n) * Purpose : get length of a string in user memory * Params : str - address of string in user memory * Returns : length of string *including terminator* * or zero on exception, or n + 1 if too long */ ENTRY(__arch_strnlen_user) stmfd sp!, {lr} mov r2, r0 1: USER( ldrbt r3, [r0], #1) teq r3, #0 beq 2f subs r1, r1, #1 bne 1b add r0, r0, #1 2: sub r0, r0, r2 LOADREGS(fd,sp!, {pc}) .section .fixup,"ax" .align 0 9001: mov r0, #0 LOADREGS(fd,sp!,{pc}) .previous /* Prototype: size_t __arch_strncpy_from_user(char *dst, char *src, size_t len) * Purpose : copy a string from user memory to kernel memory * Params : dst - kernel memory destination * : src - user memory source * : len - maximum length of string * Returns : number of characters copied */ ENTRY(__arch_strncpy_from_user) stmfd sp!, {lr} add ip, r1, #1 1: subs r2, r2, #1 bmi 2f USER( ldrbt r3, [r1], #1) strb r3, [r0], #1 teq r3, #0 bne 1b sub r0, r1, ip LOADREGS(fd, sp!, {pc}) 2: sub ip, ip, #1 sub r0, r1, ip LOADREGS(fd, sp!, {pc}) .section .fixup,"ax" .align 0 9001: mov ip, #0 1: strb ip, [r0], #1 subs r2, r2, #1 bpl 1b mov r0, #-EFAULT LOADREGS(fd, sp!, {pc}) .previous .align |