1/* 2 * linux/arch/arm/mm/alignment.c 3 * 4 * Copyright (C) 1995 Linus Torvalds 5 * Modifications for ARM processor (c) 1995-2001 Russell King 6 * Thumb alignment fault fixups (c) 2004 MontaVista Software, Inc. 7 * - Adapted from gdb/sim/arm/thumbemu.c -- Thumb instruction emulation. 8 * Copyright (C) 1996, Cygnus Software Technologies Ltd. 9 * 10 * This program is free software; you can redistribute it and/or modify 11 * it under the terms of the GNU General Public License version 2 as 12 * published by the Free Software Foundation. 13 */ 14#include <linux/moduleparam.h> 15#include <linux/compiler.h> 16#include <linux/kernel.h> 17#include <linux/errno.h> 18#include <linux/string.h> 19#include <linux/proc_fs.h> 20#include <linux/seq_file.h> 21#include <linux/init.h> 22#include <linux/sched.h> 23#include <linux/uaccess.h> 24 25#include <asm/cp15.h> 26#include <asm/system_info.h> 27#include <asm/unaligned.h> 28#include <asm/opcodes.h> 29 30#include "fault.h" 31#include "mm.h" 32 33/* 34 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998 35 * /proc/sys/debug/alignment, modified and integrated into 36 * Linux 2.1 by Russell King 37 * 38 * Speed optimisations and better fault handling by Russell King. 39 * 40 * *** NOTE *** 41 * This code is not portable to processors with late data abort handling. 42 */ 43#define CODING_BITS(i) (i & 0x0e000000) 44#define COND_BITS(i) (i & 0xf0000000) 45 46#define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */ 47#define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */ 48#define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */ 49#define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */ 50#define LDST_L_BIT(i) (i & (1 << 20)) /* Load */ 51 52#define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0) 53 54#define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */ 55#define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */ 56 57#define RN_BITS(i) ((i >> 16) & 15) /* Rn */ 58#define RD_BITS(i) ((i >> 12) & 15) /* Rd */ 59#define RM_BITS(i) (i & 15) /* Rm */ 60 61#define REGMASK_BITS(i) (i & 0xffff) 62#define OFFSET_BITS(i) (i & 0x0fff) 63 64#define IS_SHIFT(i) (i & 0x0ff0) 65#define SHIFT_BITS(i) ((i >> 7) & 0x1f) 66#define SHIFT_TYPE(i) (i & 0x60) 67#define SHIFT_LSL 0x00 68#define SHIFT_LSR 0x20 69#define SHIFT_ASR 0x40 70#define SHIFT_RORRRX 0x60 71 72#define BAD_INSTR 0xdeadc0de 73 74/* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */ 75#define IS_T32(hi16) \ 76 (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800)) 77 78static unsigned long ai_user; 79static unsigned long ai_sys; 80static void *ai_sys_last_pc; 81static unsigned long ai_skipped; 82static unsigned long ai_half; 83static unsigned long ai_word; 84static unsigned long ai_dword; 85static unsigned long ai_multi; 86static int ai_usermode; 87static unsigned long cr_no_alignment; 88 89core_param(alignment, ai_usermode, int, 0600); 90 91#define UM_WARN (1 << 0) 92#define UM_FIXUP (1 << 1) 93#define UM_SIGNAL (1 << 2) 94 95/* Return true if and only if the ARMv6 unaligned access model is in use. */ 96static bool cpu_is_v6_unaligned(void) 97{ 98 return cpu_architecture() >= CPU_ARCH_ARMv6 && get_cr() & CR_U; 99} 100 101static int safe_usermode(int new_usermode, bool warn) 102{ 103 /* 104 * ARMv6 and later CPUs can perform unaligned accesses for 105 * most single load and store instructions up to word size. 106 * LDM, STM, LDRD and STRD still need to be handled. 107 * 108 * Ignoring the alignment fault is not an option on these 109 * CPUs since we spin re-faulting the instruction without 110 * making any progress. 111 */ 112 if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) { 113 new_usermode |= UM_FIXUP; 114 115 if (warn) 116 pr_warn("alignment: ignoring faults is unsafe on this CPU. Defaulting to fixup mode.\n"); 117 } 118 119 return new_usermode; 120} 121 122#ifdef CONFIG_PROC_FS 123static const char *usermode_action[] = { 124 "ignored", 125 "warn", 126 "fixup", 127 "fixup+warn", 128 "signal", 129 "signal+warn" 130}; 131 132static int alignment_proc_show(struct seq_file *m, void *v) 133{ 134 seq_printf(m, "User:\t\t%lu\n", ai_user); 135 seq_printf(m, "System:\t\t%lu (%pF)\n", ai_sys, ai_sys_last_pc); 136 seq_printf(m, "Skipped:\t%lu\n", ai_skipped); 137 seq_printf(m, "Half:\t\t%lu\n", ai_half); 138 seq_printf(m, "Word:\t\t%lu\n", ai_word); 139 if (cpu_architecture() >= CPU_ARCH_ARMv5TE) 140 seq_printf(m, "DWord:\t\t%lu\n", ai_dword); 141 seq_printf(m, "Multi:\t\t%lu\n", ai_multi); 142 seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode, 143 usermode_action[ai_usermode]); 144 145 return 0; 146} 147 148static int alignment_proc_open(struct inode *inode, struct file *file) 149{ 150 return single_open(file, alignment_proc_show, NULL); 151} 152 153static ssize_t alignment_proc_write(struct file *file, const char __user *buffer, 154 size_t count, loff_t *pos) 155{ 156 char mode; 157 158 if (count > 0) { 159 if (get_user(mode, buffer)) 160 return -EFAULT; 161 if (mode >= '0' && mode <= '5') 162 ai_usermode = safe_usermode(mode - '0', true); 163 } 164 return count; 165} 166 167static const struct file_operations alignment_proc_fops = { 168 .open = alignment_proc_open, 169 .read = seq_read, 170 .llseek = seq_lseek, 171 .release = single_release, 172 .write = alignment_proc_write, 173}; 174#endif /* CONFIG_PROC_FS */ 175 176union offset_union { 177 unsigned long un; 178 signed long sn; 179}; 180 181#define TYPE_ERROR 0 182#define TYPE_FAULT 1 183#define TYPE_LDST 2 184#define TYPE_DONE 3 185 186#ifdef __ARMEB__ 187#define BE 1 188#define FIRST_BYTE_16 "mov %1, %1, ror #8\n" 189#define FIRST_BYTE_32 "mov %1, %1, ror #24\n" 190#define NEXT_BYTE "ror #24" 191#else 192#define BE 0 193#define FIRST_BYTE_16 194#define FIRST_BYTE_32 195#define NEXT_BYTE "lsr #8" 196#endif 197 198#define __get8_unaligned_check(ins,val,addr,err) \ 199 __asm__( \ 200 ARM( "1: "ins" %1, [%2], #1\n" ) \ 201 THUMB( "1: "ins" %1, [%2]\n" ) \ 202 THUMB( " add %2, %2, #1\n" ) \ 203 "2:\n" \ 204 " .pushsection .text.fixup,\"ax\"\n" \ 205 " .align 2\n" \ 206 "3: mov %0, #1\n" \ 207 " b 2b\n" \ 208 " .popsection\n" \ 209 " .pushsection __ex_table,\"a\"\n" \ 210 " .align 3\n" \ 211 " .long 1b, 3b\n" \ 212 " .popsection\n" \ 213 : "=r" (err), "=&r" (val), "=r" (addr) \ 214 : "0" (err), "2" (addr)) 215 216#define __get16_unaligned_check(ins,val,addr) \ 217 do { \ 218 unsigned int err = 0, v, a = addr; \ 219 __get8_unaligned_check(ins,v,a,err); \ 220 val = v << ((BE) ? 8 : 0); \ 221 __get8_unaligned_check(ins,v,a,err); \ 222 val |= v << ((BE) ? 0 : 8); \ 223 if (err) \ 224 goto fault; \ 225 } while (0) 226 227#define get16_unaligned_check(val,addr) \ 228 __get16_unaligned_check("ldrb",val,addr) 229 230#define get16t_unaligned_check(val,addr) \ 231 __get16_unaligned_check("ldrbt",val,addr) 232 233#define __get32_unaligned_check(ins,val,addr) \ 234 do { \ 235 unsigned int err = 0, v, a = addr; \ 236 __get8_unaligned_check(ins,v,a,err); \ 237 val = v << ((BE) ? 24 : 0); \ 238 __get8_unaligned_check(ins,v,a,err); \ 239 val |= v << ((BE) ? 16 : 8); \ 240 __get8_unaligned_check(ins,v,a,err); \ 241 val |= v << ((BE) ? 8 : 16); \ 242 __get8_unaligned_check(ins,v,a,err); \ 243 val |= v << ((BE) ? 0 : 24); \ 244 if (err) \ 245 goto fault; \ 246 } while (0) 247 248#define get32_unaligned_check(val,addr) \ 249 __get32_unaligned_check("ldrb",val,addr) 250 251#define get32t_unaligned_check(val,addr) \ 252 __get32_unaligned_check("ldrbt",val,addr) 253 254#define __put16_unaligned_check(ins,val,addr) \ 255 do { \ 256 unsigned int err = 0, v = val, a = addr; \ 257 __asm__( FIRST_BYTE_16 \ 258 ARM( "1: "ins" %1, [%2], #1\n" ) \ 259 THUMB( "1: "ins" %1, [%2]\n" ) \ 260 THUMB( " add %2, %2, #1\n" ) \ 261 " mov %1, %1, "NEXT_BYTE"\n" \ 262 "2: "ins" %1, [%2]\n" \ 263 "3:\n" \ 264 " .pushsection .text.fixup,\"ax\"\n" \ 265 " .align 2\n" \ 266 "4: mov %0, #1\n" \ 267 " b 3b\n" \ 268 " .popsection\n" \ 269 " .pushsection __ex_table,\"a\"\n" \ 270 " .align 3\n" \ 271 " .long 1b, 4b\n" \ 272 " .long 2b, 4b\n" \ 273 " .popsection\n" \ 274 : "=r" (err), "=&r" (v), "=&r" (a) \ 275 : "0" (err), "1" (v), "2" (a)); \ 276 if (err) \ 277 goto fault; \ 278 } while (0) 279 280#define put16_unaligned_check(val,addr) \ 281 __put16_unaligned_check("strb",val,addr) 282 283#define put16t_unaligned_check(val,addr) \ 284 __put16_unaligned_check("strbt",val,addr) 285 286#define __put32_unaligned_check(ins,val,addr) \ 287 do { \ 288 unsigned int err = 0, v = val, a = addr; \ 289 __asm__( FIRST_BYTE_32 \ 290 ARM( "1: "ins" %1, [%2], #1\n" ) \ 291 THUMB( "1: "ins" %1, [%2]\n" ) \ 292 THUMB( " add %2, %2, #1\n" ) \ 293 " mov %1, %1, "NEXT_BYTE"\n" \ 294 ARM( "2: "ins" %1, [%2], #1\n" ) \ 295 THUMB( "2: "ins" %1, [%2]\n" ) \ 296 THUMB( " add %2, %2, #1\n" ) \ 297 " mov %1, %1, "NEXT_BYTE"\n" \ 298 ARM( "3: "ins" %1, [%2], #1\n" ) \ 299 THUMB( "3: "ins" %1, [%2]\n" ) \ 300 THUMB( " add %2, %2, #1\n" ) \ 301 " mov %1, %1, "NEXT_BYTE"\n" \ 302 "4: "ins" %1, [%2]\n" \ 303 "5:\n" \ 304 " .pushsection .text.fixup,\"ax\"\n" \ 305 " .align 2\n" \ 306 "6: mov %0, #1\n" \ 307 " b 5b\n" \ 308 " .popsection\n" \ 309 " .pushsection __ex_table,\"a\"\n" \ 310 " .align 3\n" \ 311 " .long 1b, 6b\n" \ 312 " .long 2b, 6b\n" \ 313 " .long 3b, 6b\n" \ 314 " .long 4b, 6b\n" \ 315 " .popsection\n" \ 316 : "=r" (err), "=&r" (v), "=&r" (a) \ 317 : "0" (err), "1" (v), "2" (a)); \ 318 if (err) \ 319 goto fault; \ 320 } while (0) 321 322#define put32_unaligned_check(val,addr) \ 323 __put32_unaligned_check("strb", val, addr) 324 325#define put32t_unaligned_check(val,addr) \ 326 __put32_unaligned_check("strbt", val, addr) 327 328static void 329do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset) 330{ 331 if (!LDST_U_BIT(instr)) 332 offset.un = -offset.un; 333 334 if (!LDST_P_BIT(instr)) 335 addr += offset.un; 336 337 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr)) 338 regs->uregs[RN_BITS(instr)] = addr; 339} 340 341static int 342do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs) 343{ 344 unsigned int rd = RD_BITS(instr); 345 346 ai_half += 1; 347 348 if (user_mode(regs)) 349 goto user; 350 351 if (LDST_L_BIT(instr)) { 352 unsigned long val; 353 get16_unaligned_check(val, addr); 354 355 /* signed half-word? */ 356 if (instr & 0x40) 357 val = (signed long)((signed short) val); 358 359 regs->uregs[rd] = val; 360 } else 361 put16_unaligned_check(regs->uregs[rd], addr); 362 363 return TYPE_LDST; 364 365 user: 366 if (LDST_L_BIT(instr)) { 367 unsigned long val; 368 unsigned int __ua_flags = uaccess_save_and_enable(); 369 370 get16t_unaligned_check(val, addr); 371 uaccess_restore(__ua_flags); 372 373 /* signed half-word? */ 374 if (instr & 0x40) 375 val = (signed long)((signed short) val); 376 377 regs->uregs[rd] = val; 378 } else { 379 unsigned int __ua_flags = uaccess_save_and_enable(); 380 put16t_unaligned_check(regs->uregs[rd], addr); 381 uaccess_restore(__ua_flags); 382 } 383 384 return TYPE_LDST; 385 386 fault: 387 return TYPE_FAULT; 388} 389 390static int 391do_alignment_ldrdstrd(unsigned long addr, unsigned long instr, 392 struct pt_regs *regs) 393{ 394 unsigned int rd = RD_BITS(instr); 395 unsigned int rd2; 396 int load; 397 398 if ((instr & 0xfe000000) == 0xe8000000) { 399 /* ARMv7 Thumb-2 32-bit LDRD/STRD */ 400 rd2 = (instr >> 8) & 0xf; 401 load = !!(LDST_L_BIT(instr)); 402 } else if (((rd & 1) == 1) || (rd == 14)) 403 goto bad; 404 else { 405 load = ((instr & 0xf0) == 0xd0); 406 rd2 = rd + 1; 407 } 408 409 ai_dword += 1; 410 411 if (user_mode(regs)) 412 goto user; 413 414 if (load) { 415 unsigned long val; 416 get32_unaligned_check(val, addr); 417 regs->uregs[rd] = val; 418 get32_unaligned_check(val, addr + 4); 419 regs->uregs[rd2] = val; 420 } else { 421 put32_unaligned_check(regs->uregs[rd], addr); 422 put32_unaligned_check(regs->uregs[rd2], addr + 4); 423 } 424 425 return TYPE_LDST; 426 427 user: 428 if (load) { 429 unsigned long val, val2; 430 unsigned int __ua_flags = uaccess_save_and_enable(); 431 432 get32t_unaligned_check(val, addr); 433 get32t_unaligned_check(val2, addr + 4); 434 435 uaccess_restore(__ua_flags); 436 437 regs->uregs[rd] = val; 438 regs->uregs[rd2] = val2; 439 } else { 440 unsigned int __ua_flags = uaccess_save_and_enable(); 441 put32t_unaligned_check(regs->uregs[rd], addr); 442 put32t_unaligned_check(regs->uregs[rd2], addr + 4); 443 uaccess_restore(__ua_flags); 444 } 445 446 return TYPE_LDST; 447 bad: 448 return TYPE_ERROR; 449 fault: 450 return TYPE_FAULT; 451} 452 453static int 454do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs) 455{ 456 unsigned int rd = RD_BITS(instr); 457 458 ai_word += 1; 459 460 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs)) 461 goto trans; 462 463 if (LDST_L_BIT(instr)) { 464 unsigned int val; 465 get32_unaligned_check(val, addr); 466 regs->uregs[rd] = val; 467 } else 468 put32_unaligned_check(regs->uregs[rd], addr); 469 return TYPE_LDST; 470 471 trans: 472 if (LDST_L_BIT(instr)) { 473 unsigned int val; 474 unsigned int __ua_flags = uaccess_save_and_enable(); 475 get32t_unaligned_check(val, addr); 476 uaccess_restore(__ua_flags); 477 regs->uregs[rd] = val; 478 } else { 479 unsigned int __ua_flags = uaccess_save_and_enable(); 480 put32t_unaligned_check(regs->uregs[rd], addr); 481 uaccess_restore(__ua_flags); 482 } 483 return TYPE_LDST; 484 485 fault: 486 return TYPE_FAULT; 487} 488 489/* 490 * LDM/STM alignment handler. 491 * 492 * There are 4 variants of this instruction: 493 * 494 * B = rn pointer before instruction, A = rn pointer after instruction 495 * ------ increasing address -----> 496 * | | r0 | r1 | ... | rx | | 497 * PU = 01 B A 498 * PU = 11 B A 499 * PU = 00 A B 500 * PU = 10 A B 501 */ 502static int 503do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs) 504{ 505 unsigned int rd, rn, correction, nr_regs, regbits; 506 unsigned long eaddr, newaddr; 507 508 if (LDM_S_BIT(instr)) 509 goto bad; 510 511 correction = 4; /* processor implementation defined */ 512 regs->ARM_pc += correction; 513 514 ai_multi += 1; 515 516 /* count the number of registers in the mask to be transferred */ 517 nr_regs = hweight16(REGMASK_BITS(instr)) * 4; 518 519 rn = RN_BITS(instr); 520 newaddr = eaddr = regs->uregs[rn]; 521 522 if (!LDST_U_BIT(instr)) 523 nr_regs = -nr_regs; 524 newaddr += nr_regs; 525 if (!LDST_U_BIT(instr)) 526 eaddr = newaddr; 527 528 if (LDST_P_EQ_U(instr)) /* U = P */ 529 eaddr += 4; 530 531 /* 532 * For alignment faults on the ARM922T/ARM920T the MMU makes 533 * the FSR (and hence addr) equal to the updated base address 534 * of the multiple access rather than the restored value. 535 * Switch this message off if we've got a ARM92[02], otherwise 536 * [ls]dm alignment faults are noisy! 537 */ 538#if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T) 539 /* 540 * This is a "hint" - we already have eaddr worked out by the 541 * processor for us. 542 */ 543 if (addr != eaddr) { 544 pr_err("LDMSTM: PC = %08lx, instr = %08lx, " 545 "addr = %08lx, eaddr = %08lx\n", 546 instruction_pointer(regs), instr, addr, eaddr); 547 show_regs(regs); 548 } 549#endif 550 551 if (user_mode(regs)) { 552 unsigned int __ua_flags = uaccess_save_and_enable(); 553 for (regbits = REGMASK_BITS(instr), rd = 0; regbits; 554 regbits >>= 1, rd += 1) 555 if (regbits & 1) { 556 if (LDST_L_BIT(instr)) { 557 unsigned int val; 558 get32t_unaligned_check(val, eaddr); 559 regs->uregs[rd] = val; 560 } else 561 put32t_unaligned_check(regs->uregs[rd], eaddr); 562 eaddr += 4; 563 } 564 uaccess_restore(__ua_flags); 565 } else { 566 for (regbits = REGMASK_BITS(instr), rd = 0; regbits; 567 regbits >>= 1, rd += 1) 568 if (regbits & 1) { 569 if (LDST_L_BIT(instr)) { 570 unsigned int val; 571 get32_unaligned_check(val, eaddr); 572 regs->uregs[rd] = val; 573 } else 574 put32_unaligned_check(regs->uregs[rd], eaddr); 575 eaddr += 4; 576 } 577 } 578 579 if (LDST_W_BIT(instr)) 580 regs->uregs[rn] = newaddr; 581 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15))) 582 regs->ARM_pc -= correction; 583 return TYPE_DONE; 584 585fault: 586 regs->ARM_pc -= correction; 587 return TYPE_FAULT; 588 589bad: 590 pr_err("Alignment trap: not handling ldm with s-bit set\n"); 591 return TYPE_ERROR; 592} 593 594/* 595 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so 596 * we can reuse ARM userland alignment fault fixups for Thumb. 597 * 598 * This implementation was initially based on the algorithm found in 599 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same 600 * to convert only Thumb ld/st instruction forms to equivalent ARM forms. 601 * 602 * NOTES: 603 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections. 604 * 2. If for some reason we're passed an non-ld/st Thumb instruction to 605 * decode, we return 0xdeadc0de. This should never happen under normal 606 * circumstances but if it does, we've got other problems to deal with 607 * elsewhere and we obviously can't fix those problems here. 608 */ 609 610static unsigned long 611thumb2arm(u16 tinstr) 612{ 613 u32 L = (tinstr & (1<<11)) >> 11; 614 615 switch ((tinstr & 0xf800) >> 11) { 616 /* 6.5.1 Format 1: */ 617 case 0x6000 >> 11: /* 7.1.52 STR(1) */ 618 case 0x6800 >> 11: /* 7.1.26 LDR(1) */ 619 case 0x7000 >> 11: /* 7.1.55 STRB(1) */ 620 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */ 621 return 0xe5800000 | 622 ((tinstr & (1<<12)) << (22-12)) | /* fixup */ 623 (L<<20) | /* L==1? */ 624 ((tinstr & (7<<0)) << (12-0)) | /* Rd */ 625 ((tinstr & (7<<3)) << (16-3)) | /* Rn */ 626 ((tinstr & (31<<6)) >> /* immed_5 */ 627 (6 - ((tinstr & (1<<12)) ? 0 : 2))); 628 case 0x8000 >> 11: /* 7.1.57 STRH(1) */ 629 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */ 630 return 0xe1c000b0 | 631 (L<<20) | /* L==1? */ 632 ((tinstr & (7<<0)) << (12-0)) | /* Rd */ 633 ((tinstr & (7<<3)) << (16-3)) | /* Rn */ 634 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */ 635 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */ 636 637 /* 6.5.1 Format 2: */ 638 case 0x5000 >> 11: 639 case 0x5800 >> 11: 640 { 641 static const u32 subset[8] = { 642 0xe7800000, /* 7.1.53 STR(2) */ 643 0xe18000b0, /* 7.1.58 STRH(2) */ 644 0xe7c00000, /* 7.1.56 STRB(2) */ 645 0xe19000d0, /* 7.1.34 LDRSB */ 646 0xe7900000, /* 7.1.27 LDR(2) */ 647 0xe19000b0, /* 7.1.33 LDRH(2) */ 648 0xe7d00000, /* 7.1.31 LDRB(2) */ 649 0xe19000f0 /* 7.1.35 LDRSH */ 650 }; 651 return subset[(tinstr & (7<<9)) >> 9] | 652 ((tinstr & (7<<0)) << (12-0)) | /* Rd */ 653 ((tinstr & (7<<3)) << (16-3)) | /* Rn */ 654 ((tinstr & (7<<6)) >> (6-0)); /* Rm */ 655 } 656 657 /* 6.5.1 Format 3: */ 658 case 0x4800 >> 11: /* 7.1.28 LDR(3) */ 659 /* NOTE: This case is not technically possible. We're 660 * loading 32-bit memory data via PC relative 661 * addressing mode. So we can and should eliminate 662 * this case. But I'll leave it here for now. 663 */ 664 return 0xe59f0000 | 665 ((tinstr & (7<<8)) << (12-8)) | /* Rd */ 666 ((tinstr & 255) << (2-0)); /* immed_8 */ 667 668 /* 6.5.1 Format 4: */ 669 case 0x9000 >> 11: /* 7.1.54 STR(3) */ 670 case 0x9800 >> 11: /* 7.1.29 LDR(4) */ 671 return 0xe58d0000 | 672 (L<<20) | /* L==1? */ 673 ((tinstr & (7<<8)) << (12-8)) | /* Rd */ 674 ((tinstr & 255) << 2); /* immed_8 */ 675 676 /* 6.6.1 Format 1: */ 677 case 0xc000 >> 11: /* 7.1.51 STMIA */ 678 case 0xc800 >> 11: /* 7.1.25 LDMIA */ 679 { 680 u32 Rn = (tinstr & (7<<8)) >> 8; 681 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21; 682 683 return 0xe8800000 | W | (L<<20) | (Rn<<16) | 684 (tinstr&255); 685 } 686 687 /* 6.6.1 Format 2: */ 688 case 0xb000 >> 11: /* 7.1.48 PUSH */ 689 case 0xb800 >> 11: /* 7.1.47 POP */ 690 if ((tinstr & (3 << 9)) == 0x0400) { 691 static const u32 subset[4] = { 692 0xe92d0000, /* STMDB sp!,{registers} */ 693 0xe92d4000, /* STMDB sp!,{registers,lr} */ 694 0xe8bd0000, /* LDMIA sp!,{registers} */ 695 0xe8bd8000 /* LDMIA sp!,{registers,pc} */ 696 }; 697 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] | 698 (tinstr & 255); /* register_list */ 699 } 700 /* Else fall through for illegal instruction case */ 701 702 default: 703 return BAD_INSTR; 704 } 705} 706 707/* 708 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction 709 * handlable by ARM alignment handler, also find the corresponding handler, 710 * so that we can reuse ARM userland alignment fault fixups for Thumb. 711 * 712 * @pinstr: original Thumb-2 instruction; returns new handlable instruction 713 * @regs: register context. 714 * @poffset: return offset from faulted addr for later writeback 715 * 716 * NOTES: 717 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections. 718 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt) 719 */ 720static void * 721do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs, 722 union offset_union *poffset) 723{ 724 unsigned long instr = *pinstr; 725 u16 tinst1 = (instr >> 16) & 0xffff; 726 u16 tinst2 = instr & 0xffff; 727 728 switch (tinst1 & 0xffe0) { 729 /* A6.3.5 Load/Store multiple */ 730 case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */ 731 case 0xe8a0: /* ...above writeback version */ 732 case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */ 733 case 0xe920: /* ...above writeback version */ 734 /* no need offset decision since handler calculates it */ 735 return do_alignment_ldmstm; 736 737 case 0xf840: /* POP/PUSH T3 (single register) */ 738 if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) { 739 u32 L = !!(LDST_L_BIT(instr)); 740 const u32 subset[2] = { 741 0xe92d0000, /* STMDB sp!,{registers} */ 742 0xe8bd0000, /* LDMIA sp!,{registers} */ 743 }; 744 *pinstr = subset[L] | (1<<RD_BITS(instr)); 745 return do_alignment_ldmstm; 746 } 747 /* Else fall through for illegal instruction case */ 748 break; 749 750 /* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */ 751 case 0xe860: 752 case 0xe960: 753 case 0xe8e0: 754 case 0xe9e0: 755 poffset->un = (tinst2 & 0xff) << 2; 756 case 0xe940: 757 case 0xe9c0: 758 return do_alignment_ldrdstrd; 759 760 /* 761 * No need to handle load/store instructions up to word size 762 * since ARMv6 and later CPUs can perform unaligned accesses. 763 */ 764 default: 765 break; 766 } 767 return NULL; 768} 769 770static int 771do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 772{ 773 union offset_union uninitialized_var(offset); 774 unsigned long instr = 0, instrptr; 775 int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs); 776 unsigned int type; 777 unsigned int fault; 778 u16 tinstr = 0; 779 int isize = 4; 780 int thumb2_32b = 0; 781 782 if (interrupts_enabled(regs)) 783 local_irq_enable(); 784 785 instrptr = instruction_pointer(regs); 786 787 if (thumb_mode(regs)) { 788 u16 *ptr = (u16 *)(instrptr & ~1); 789 fault = probe_kernel_address(ptr, tinstr); 790 tinstr = __mem_to_opcode_thumb16(tinstr); 791 if (!fault) { 792 if (cpu_architecture() >= CPU_ARCH_ARMv7 && 793 IS_T32(tinstr)) { 794 /* Thumb-2 32-bit */ 795 u16 tinst2 = 0; 796 fault = probe_kernel_address(ptr + 1, tinst2); 797 tinst2 = __mem_to_opcode_thumb16(tinst2); 798 instr = __opcode_thumb32_compose(tinstr, tinst2); 799 thumb2_32b = 1; 800 } else { 801 isize = 2; 802 instr = thumb2arm(tinstr); 803 } 804 } 805 } else { 806 fault = probe_kernel_address((void *)instrptr, instr); 807 instr = __mem_to_opcode_arm(instr); 808 } 809 810 if (fault) { 811 type = TYPE_FAULT; 812 goto bad_or_fault; 813 } 814 815 if (user_mode(regs)) 816 goto user; 817 818 ai_sys += 1; 819 ai_sys_last_pc = (void *)instruction_pointer(regs); 820 821 fixup: 822 823 regs->ARM_pc += isize; 824 825 switch (CODING_BITS(instr)) { 826 case 0x00000000: /* 3.13.4 load/store instruction extensions */ 827 if (LDSTHD_I_BIT(instr)) 828 offset.un = (instr & 0xf00) >> 4 | (instr & 15); 829 else 830 offset.un = regs->uregs[RM_BITS(instr)]; 831 832 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */ 833 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */ 834 handler = do_alignment_ldrhstrh; 835 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */ 836 (instr & 0x001000f0) == 0x000000f0) /* STRD */ 837 handler = do_alignment_ldrdstrd; 838 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */ 839 goto swp; 840 else 841 goto bad; 842 break; 843 844 case 0x04000000: /* ldr or str immediate */ 845 if (COND_BITS(instr) == 0xf0000000) /* NEON VLDn, VSTn */ 846 goto bad; 847 offset.un = OFFSET_BITS(instr); 848 handler = do_alignment_ldrstr; 849 break; 850 851 case 0x06000000: /* ldr or str register */ 852 offset.un = regs->uregs[RM_BITS(instr)]; 853 854 if (IS_SHIFT(instr)) { 855 unsigned int shiftval = SHIFT_BITS(instr); 856 857 switch(SHIFT_TYPE(instr)) { 858 case SHIFT_LSL: 859 offset.un <<= shiftval; 860 break; 861 862 case SHIFT_LSR: 863 offset.un >>= shiftval; 864 break; 865 866 case SHIFT_ASR: 867 offset.sn >>= shiftval; 868 break; 869 870 case SHIFT_RORRRX: 871 if (shiftval == 0) { 872 offset.un >>= 1; 873 if (regs->ARM_cpsr & PSR_C_BIT) 874 offset.un |= 1 << 31; 875 } else 876 offset.un = offset.un >> shiftval | 877 offset.un << (32 - shiftval); 878 break; 879 } 880 } 881 handler = do_alignment_ldrstr; 882 break; 883 884 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */ 885 if (thumb2_32b) { 886 offset.un = 0; 887 handler = do_alignment_t32_to_handler(&instr, regs, &offset); 888 } else { 889 offset.un = 0; 890 handler = do_alignment_ldmstm; 891 } 892 break; 893 894 default: 895 goto bad; 896 } 897 898 if (!handler) 899 goto bad; 900 type = handler(addr, instr, regs); 901 902 if (type == TYPE_ERROR || type == TYPE_FAULT) { 903 regs->ARM_pc -= isize; 904 goto bad_or_fault; 905 } 906 907 if (type == TYPE_LDST) 908 do_alignment_finish_ldst(addr, instr, regs, offset); 909 910 return 0; 911 912 bad_or_fault: 913 if (type == TYPE_ERROR) 914 goto bad; 915 /* 916 * We got a fault - fix it up, or die. 917 */ 918 do_bad_area(addr, fsr, regs); 919 return 0; 920 921 swp: 922 pr_err("Alignment trap: not handling swp instruction\n"); 923 924 bad: 925 /* 926 * Oops, we didn't handle the instruction. 927 */ 928 pr_err("Alignment trap: not handling instruction " 929 "%0*lx at [<%08lx>]\n", 930 isize << 1, 931 isize == 2 ? tinstr : instr, instrptr); 932 ai_skipped += 1; 933 return 1; 934 935 user: 936 ai_user += 1; 937 938 if (ai_usermode & UM_WARN) 939 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx " 940 "Address=0x%08lx FSR 0x%03x\n", current->comm, 941 task_pid_nr(current), instrptr, 942 isize << 1, 943 isize == 2 ? tinstr : instr, 944 addr, fsr); 945 946 if (ai_usermode & UM_FIXUP) 947 goto fixup; 948 949 if (ai_usermode & UM_SIGNAL) { 950 siginfo_t si; 951 952 si.si_signo = SIGBUS; 953 si.si_errno = 0; 954 si.si_code = BUS_ADRALN; 955 si.si_addr = (void __user *)addr; 956 957 force_sig_info(si.si_signo, &si, current); 958 } else { 959 /* 960 * We're about to disable the alignment trap and return to 961 * user space. But if an interrupt occurs before actually 962 * reaching user space, then the IRQ vector entry code will 963 * notice that we were still in kernel space and therefore 964 * the alignment trap won't be re-enabled in that case as it 965 * is presumed to be always on from kernel space. 966 * Let's prevent that race by disabling interrupts here (they 967 * are disabled on the way back to user space anyway in 968 * entry-common.S) and disable the alignment trap only if 969 * there is no work pending for this thread. 970 */ 971 raw_local_irq_disable(); 972 if (!(current_thread_info()->flags & _TIF_WORK_MASK)) 973 set_cr(cr_no_alignment); 974 } 975 976 return 0; 977} 978 979static int __init noalign_setup(char *__unused) 980{ 981 set_cr(__clear_cr(CR_A)); 982 return 1; 983} 984__setup("noalign", noalign_setup); 985 986/* 987 * This needs to be done after sysctl_init, otherwise sys/ will be 988 * overwritten. Actually, this shouldn't be in sys/ at all since 989 * it isn't a sysctl, and it doesn't contain sysctl information. 990 * We now locate it in /proc/cpu/alignment instead. 991 */ 992static int __init alignment_init(void) 993{ 994#ifdef CONFIG_PROC_FS 995 struct proc_dir_entry *res; 996 997 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL, 998 &alignment_proc_fops); 999 if (!res) 1000 return -ENOMEM; 1001#endif 1002 1003 if (cpu_is_v6_unaligned()) { 1004 set_cr(__clear_cr(CR_A)); 1005 ai_usermode = safe_usermode(ai_usermode, false); 1006 } 1007 1008 cr_no_alignment = get_cr() & ~CR_A; 1009 1010 hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN, 1011 "alignment exception"); 1012 1013 /* 1014 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section 1015 * fault, not as alignment error. 1016 * 1017 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is 1018 * needed. 1019 */ 1020 if (cpu_architecture() <= CPU_ARCH_ARMv6) { 1021 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN, 1022 "alignment exception"); 1023 } 1024 1025 return 0; 1026} 1027 1028fs_initcall(alignment_init); 1029