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/sched/debug.h> 18 #include <linux/errno.h> 19 #include <linux/string.h> 20 #include <linux/proc_fs.h> 21 #include <linux/seq_file.h> 22 #include <linux/init.h> 23 #include <linux/sched/signal.h> 24 #include <linux/uaccess.h> 25 26 #include <asm/cp15.h> 27 #include <asm/system_info.h> 28 #include <asm/unaligned.h> 29 #include <asm/opcodes.h> 30 31 #include "fault.h" 32 #include "mm.h" 33 34 /* 35 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998 36 * /proc/sys/debug/alignment, modified and integrated into 37 * Linux 2.1 by Russell King 38 * 39 * Speed optimisations and better fault handling by Russell King. 40 * 41 * *** NOTE *** 42 * This code is not portable to processors with late data abort handling. 43 */ 44 #define CODING_BITS(i) (i & 0x0e000000) 45 #define COND_BITS(i) (i & 0xf0000000) 46 47 #define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */ 48 #define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */ 49 #define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */ 50 #define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */ 51 #define LDST_L_BIT(i) (i & (1 << 20)) /* Load */ 52 53 #define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0) 54 55 #define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */ 56 #define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */ 57 58 #define RN_BITS(i) ((i >> 16) & 15) /* Rn */ 59 #define RD_BITS(i) ((i >> 12) & 15) /* Rd */ 60 #define RM_BITS(i) (i & 15) /* Rm */ 61 62 #define REGMASK_BITS(i) (i & 0xffff) 63 #define OFFSET_BITS(i) (i & 0x0fff) 64 65 #define IS_SHIFT(i) (i & 0x0ff0) 66 #define SHIFT_BITS(i) ((i >> 7) & 0x1f) 67 #define SHIFT_TYPE(i) (i & 0x60) 68 #define SHIFT_LSL 0x00 69 #define SHIFT_LSR 0x20 70 #define SHIFT_ASR 0x40 71 #define SHIFT_RORRRX 0x60 72 73 #define BAD_INSTR 0xdeadc0de 74 75 /* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */ 76 #define IS_T32(hi16) \ 77 (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800)) 78 79 static unsigned long ai_user; 80 static unsigned long ai_sys; 81 static void *ai_sys_last_pc; 82 static unsigned long ai_skipped; 83 static unsigned long ai_half; 84 static unsigned long ai_word; 85 static unsigned long ai_dword; 86 static unsigned long ai_multi; 87 static int ai_usermode; 88 static unsigned long cr_no_alignment; 89 90 core_param(alignment, ai_usermode, int, 0600); 91 92 #define UM_WARN (1 << 0) 93 #define UM_FIXUP (1 << 1) 94 #define UM_SIGNAL (1 << 2) 95 96 /* Return true if and only if the ARMv6 unaligned access model is in use. */ 97 static bool cpu_is_v6_unaligned(void) 98 { 99 return cpu_architecture() >= CPU_ARCH_ARMv6 && get_cr() & CR_U; 100 } 101 102 static int safe_usermode(int new_usermode, bool warn) 103 { 104 /* 105 * ARMv6 and later CPUs can perform unaligned accesses for 106 * most single load and store instructions up to word size. 107 * LDM, STM, LDRD and STRD still need to be handled. 108 * 109 * Ignoring the alignment fault is not an option on these 110 * CPUs since we spin re-faulting the instruction without 111 * making any progress. 112 */ 113 if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) { 114 new_usermode |= UM_FIXUP; 115 116 if (warn) 117 pr_warn("alignment: ignoring faults is unsafe on this CPU. Defaulting to fixup mode.\n"); 118 } 119 120 return new_usermode; 121 } 122 123 #ifdef CONFIG_PROC_FS 124 static const char *usermode_action[] = { 125 "ignored", 126 "warn", 127 "fixup", 128 "fixup+warn", 129 "signal", 130 "signal+warn" 131 }; 132 133 static int alignment_proc_show(struct seq_file *m, void *v) 134 { 135 seq_printf(m, "User:\t\t%lu\n", ai_user); 136 seq_printf(m, "System:\t\t%lu (%pF)\n", ai_sys, ai_sys_last_pc); 137 seq_printf(m, "Skipped:\t%lu\n", ai_skipped); 138 seq_printf(m, "Half:\t\t%lu\n", ai_half); 139 seq_printf(m, "Word:\t\t%lu\n", ai_word); 140 if (cpu_architecture() >= CPU_ARCH_ARMv5TE) 141 seq_printf(m, "DWord:\t\t%lu\n", ai_dword); 142 seq_printf(m, "Multi:\t\t%lu\n", ai_multi); 143 seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode, 144 usermode_action[ai_usermode]); 145 146 return 0; 147 } 148 149 static int alignment_proc_open(struct inode *inode, struct file *file) 150 { 151 return single_open(file, alignment_proc_show, NULL); 152 } 153 154 static ssize_t alignment_proc_write(struct file *file, const char __user *buffer, 155 size_t count, loff_t *pos) 156 { 157 char mode; 158 159 if (count > 0) { 160 if (get_user(mode, buffer)) 161 return -EFAULT; 162 if (mode >= '0' && mode <= '5') 163 ai_usermode = safe_usermode(mode - '0', true); 164 } 165 return count; 166 } 167 168 static const struct file_operations alignment_proc_fops = { 169 .open = alignment_proc_open, 170 .read = seq_read, 171 .llseek = seq_lseek, 172 .release = single_release, 173 .write = alignment_proc_write, 174 }; 175 #endif /* CONFIG_PROC_FS */ 176 177 union offset_union { 178 unsigned long un; 179 signed long sn; 180 }; 181 182 #define TYPE_ERROR 0 183 #define TYPE_FAULT 1 184 #define TYPE_LDST 2 185 #define TYPE_DONE 3 186 187 #ifdef __ARMEB__ 188 #define BE 1 189 #define FIRST_BYTE_16 "mov %1, %1, ror #8\n" 190 #define FIRST_BYTE_32 "mov %1, %1, ror #24\n" 191 #define NEXT_BYTE "ror #24" 192 #else 193 #define BE 0 194 #define FIRST_BYTE_16 195 #define FIRST_BYTE_32 196 #define NEXT_BYTE "lsr #8" 197 #endif 198 199 #define __get8_unaligned_check(ins,val,addr,err) \ 200 __asm__( \ 201 ARM( "1: "ins" %1, [%2], #1\n" ) \ 202 THUMB( "1: "ins" %1, [%2]\n" ) \ 203 THUMB( " add %2, %2, #1\n" ) \ 204 "2:\n" \ 205 " .pushsection .text.fixup,\"ax\"\n" \ 206 " .align 2\n" \ 207 "3: mov %0, #1\n" \ 208 " b 2b\n" \ 209 " .popsection\n" \ 210 " .pushsection __ex_table,\"a\"\n" \ 211 " .align 3\n" \ 212 " .long 1b, 3b\n" \ 213 " .popsection\n" \ 214 : "=r" (err), "=&r" (val), "=r" (addr) \ 215 : "0" (err), "2" (addr)) 216 217 #define __get16_unaligned_check(ins,val,addr) \ 218 do { \ 219 unsigned int err = 0, v, a = addr; \ 220 __get8_unaligned_check(ins,v,a,err); \ 221 val = v << ((BE) ? 8 : 0); \ 222 __get8_unaligned_check(ins,v,a,err); \ 223 val |= v << ((BE) ? 0 : 8); \ 224 if (err) \ 225 goto fault; \ 226 } while (0) 227 228 #define get16_unaligned_check(val,addr) \ 229 __get16_unaligned_check("ldrb",val,addr) 230 231 #define get16t_unaligned_check(val,addr) \ 232 __get16_unaligned_check("ldrbt",val,addr) 233 234 #define __get32_unaligned_check(ins,val,addr) \ 235 do { \ 236 unsigned int err = 0, v, a = addr; \ 237 __get8_unaligned_check(ins,v,a,err); \ 238 val = v << ((BE) ? 24 : 0); \ 239 __get8_unaligned_check(ins,v,a,err); \ 240 val |= v << ((BE) ? 16 : 8); \ 241 __get8_unaligned_check(ins,v,a,err); \ 242 val |= v << ((BE) ? 8 : 16); \ 243 __get8_unaligned_check(ins,v,a,err); \ 244 val |= v << ((BE) ? 0 : 24); \ 245 if (err) \ 246 goto fault; \ 247 } while (0) 248 249 #define get32_unaligned_check(val,addr) \ 250 __get32_unaligned_check("ldrb",val,addr) 251 252 #define get32t_unaligned_check(val,addr) \ 253 __get32_unaligned_check("ldrbt",val,addr) 254 255 #define __put16_unaligned_check(ins,val,addr) \ 256 do { \ 257 unsigned int err = 0, v = val, a = addr; \ 258 __asm__( FIRST_BYTE_16 \ 259 ARM( "1: "ins" %1, [%2], #1\n" ) \ 260 THUMB( "1: "ins" %1, [%2]\n" ) \ 261 THUMB( " add %2, %2, #1\n" ) \ 262 " mov %1, %1, "NEXT_BYTE"\n" \ 263 "2: "ins" %1, [%2]\n" \ 264 "3:\n" \ 265 " .pushsection .text.fixup,\"ax\"\n" \ 266 " .align 2\n" \ 267 "4: mov %0, #1\n" \ 268 " b 3b\n" \ 269 " .popsection\n" \ 270 " .pushsection __ex_table,\"a\"\n" \ 271 " .align 3\n" \ 272 " .long 1b, 4b\n" \ 273 " .long 2b, 4b\n" \ 274 " .popsection\n" \ 275 : "=r" (err), "=&r" (v), "=&r" (a) \ 276 : "0" (err), "1" (v), "2" (a)); \ 277 if (err) \ 278 goto fault; \ 279 } while (0) 280 281 #define put16_unaligned_check(val,addr) \ 282 __put16_unaligned_check("strb",val,addr) 283 284 #define put16t_unaligned_check(val,addr) \ 285 __put16_unaligned_check("strbt",val,addr) 286 287 #define __put32_unaligned_check(ins,val,addr) \ 288 do { \ 289 unsigned int err = 0, v = val, a = addr; \ 290 __asm__( FIRST_BYTE_32 \ 291 ARM( "1: "ins" %1, [%2], #1\n" ) \ 292 THUMB( "1: "ins" %1, [%2]\n" ) \ 293 THUMB( " add %2, %2, #1\n" ) \ 294 " mov %1, %1, "NEXT_BYTE"\n" \ 295 ARM( "2: "ins" %1, [%2], #1\n" ) \ 296 THUMB( "2: "ins" %1, [%2]\n" ) \ 297 THUMB( " add %2, %2, #1\n" ) \ 298 " mov %1, %1, "NEXT_BYTE"\n" \ 299 ARM( "3: "ins" %1, [%2], #1\n" ) \ 300 THUMB( "3: "ins" %1, [%2]\n" ) \ 301 THUMB( " add %2, %2, #1\n" ) \ 302 " mov %1, %1, "NEXT_BYTE"\n" \ 303 "4: "ins" %1, [%2]\n" \ 304 "5:\n" \ 305 " .pushsection .text.fixup,\"ax\"\n" \ 306 " .align 2\n" \ 307 "6: mov %0, #1\n" \ 308 " b 5b\n" \ 309 " .popsection\n" \ 310 " .pushsection __ex_table,\"a\"\n" \ 311 " .align 3\n" \ 312 " .long 1b, 6b\n" \ 313 " .long 2b, 6b\n" \ 314 " .long 3b, 6b\n" \ 315 " .long 4b, 6b\n" \ 316 " .popsection\n" \ 317 : "=r" (err), "=&r" (v), "=&r" (a) \ 318 : "0" (err), "1" (v), "2" (a)); \ 319 if (err) \ 320 goto fault; \ 321 } while (0) 322 323 #define put32_unaligned_check(val,addr) \ 324 __put32_unaligned_check("strb", val, addr) 325 326 #define put32t_unaligned_check(val,addr) \ 327 __put32_unaligned_check("strbt", val, addr) 328 329 static void 330 do_alignment_finish_ldst(unsigned long addr, unsigned long instr, struct pt_regs *regs, union offset_union offset) 331 { 332 if (!LDST_U_BIT(instr)) 333 offset.un = -offset.un; 334 335 if (!LDST_P_BIT(instr)) 336 addr += offset.un; 337 338 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr)) 339 regs->uregs[RN_BITS(instr)] = addr; 340 } 341 342 static int 343 do_alignment_ldrhstrh(unsigned long addr, unsigned long instr, struct pt_regs *regs) 344 { 345 unsigned int rd = RD_BITS(instr); 346 347 ai_half += 1; 348 349 if (user_mode(regs)) 350 goto user; 351 352 if (LDST_L_BIT(instr)) { 353 unsigned long val; 354 get16_unaligned_check(val, addr); 355 356 /* signed half-word? */ 357 if (instr & 0x40) 358 val = (signed long)((signed short) val); 359 360 regs->uregs[rd] = val; 361 } else 362 put16_unaligned_check(regs->uregs[rd], addr); 363 364 return TYPE_LDST; 365 366 user: 367 if (LDST_L_BIT(instr)) { 368 unsigned long val; 369 unsigned int __ua_flags = uaccess_save_and_enable(); 370 371 get16t_unaligned_check(val, addr); 372 uaccess_restore(__ua_flags); 373 374 /* signed half-word? */ 375 if (instr & 0x40) 376 val = (signed long)((signed short) val); 377 378 regs->uregs[rd] = val; 379 } else { 380 unsigned int __ua_flags = uaccess_save_and_enable(); 381 put16t_unaligned_check(regs->uregs[rd], addr); 382 uaccess_restore(__ua_flags); 383 } 384 385 return TYPE_LDST; 386 387 fault: 388 return TYPE_FAULT; 389 } 390 391 static int 392 do_alignment_ldrdstrd(unsigned long addr, unsigned long instr, 393 struct pt_regs *regs) 394 { 395 unsigned int rd = RD_BITS(instr); 396 unsigned int rd2; 397 int load; 398 399 if ((instr & 0xfe000000) == 0xe8000000) { 400 /* ARMv7 Thumb-2 32-bit LDRD/STRD */ 401 rd2 = (instr >> 8) & 0xf; 402 load = !!(LDST_L_BIT(instr)); 403 } else if (((rd & 1) == 1) || (rd == 14)) 404 goto bad; 405 else { 406 load = ((instr & 0xf0) == 0xd0); 407 rd2 = rd + 1; 408 } 409 410 ai_dword += 1; 411 412 if (user_mode(regs)) 413 goto user; 414 415 if (load) { 416 unsigned long val; 417 get32_unaligned_check(val, addr); 418 regs->uregs[rd] = val; 419 get32_unaligned_check(val, addr + 4); 420 regs->uregs[rd2] = val; 421 } else { 422 put32_unaligned_check(regs->uregs[rd], addr); 423 put32_unaligned_check(regs->uregs[rd2], addr + 4); 424 } 425 426 return TYPE_LDST; 427 428 user: 429 if (load) { 430 unsigned long val, val2; 431 unsigned int __ua_flags = uaccess_save_and_enable(); 432 433 get32t_unaligned_check(val, addr); 434 get32t_unaligned_check(val2, addr + 4); 435 436 uaccess_restore(__ua_flags); 437 438 regs->uregs[rd] = val; 439 regs->uregs[rd2] = val2; 440 } else { 441 unsigned int __ua_flags = uaccess_save_and_enable(); 442 put32t_unaligned_check(regs->uregs[rd], addr); 443 put32t_unaligned_check(regs->uregs[rd2], addr + 4); 444 uaccess_restore(__ua_flags); 445 } 446 447 return TYPE_LDST; 448 bad: 449 return TYPE_ERROR; 450 fault: 451 return TYPE_FAULT; 452 } 453 454 static int 455 do_alignment_ldrstr(unsigned long addr, unsigned long instr, struct pt_regs *regs) 456 { 457 unsigned int rd = RD_BITS(instr); 458 459 ai_word += 1; 460 461 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs)) 462 goto trans; 463 464 if (LDST_L_BIT(instr)) { 465 unsigned int val; 466 get32_unaligned_check(val, addr); 467 regs->uregs[rd] = val; 468 } else 469 put32_unaligned_check(regs->uregs[rd], addr); 470 return TYPE_LDST; 471 472 trans: 473 if (LDST_L_BIT(instr)) { 474 unsigned int val; 475 unsigned int __ua_flags = uaccess_save_and_enable(); 476 get32t_unaligned_check(val, addr); 477 uaccess_restore(__ua_flags); 478 regs->uregs[rd] = val; 479 } else { 480 unsigned int __ua_flags = uaccess_save_and_enable(); 481 put32t_unaligned_check(regs->uregs[rd], addr); 482 uaccess_restore(__ua_flags); 483 } 484 return TYPE_LDST; 485 486 fault: 487 return TYPE_FAULT; 488 } 489 490 /* 491 * LDM/STM alignment handler. 492 * 493 * There are 4 variants of this instruction: 494 * 495 * B = rn pointer before instruction, A = rn pointer after instruction 496 * ------ increasing address -----> 497 * | | r0 | r1 | ... | rx | | 498 * PU = 01 B A 499 * PU = 11 B A 500 * PU = 00 A B 501 * PU = 10 A B 502 */ 503 static int 504 do_alignment_ldmstm(unsigned long addr, unsigned long instr, struct pt_regs *regs) 505 { 506 unsigned int rd, rn, correction, nr_regs, regbits; 507 unsigned long eaddr, newaddr; 508 509 if (LDM_S_BIT(instr)) 510 goto bad; 511 512 correction = 4; /* processor implementation defined */ 513 regs->ARM_pc += correction; 514 515 ai_multi += 1; 516 517 /* count the number of registers in the mask to be transferred */ 518 nr_regs = hweight16(REGMASK_BITS(instr)) * 4; 519 520 rn = RN_BITS(instr); 521 newaddr = eaddr = regs->uregs[rn]; 522 523 if (!LDST_U_BIT(instr)) 524 nr_regs = -nr_regs; 525 newaddr += nr_regs; 526 if (!LDST_U_BIT(instr)) 527 eaddr = newaddr; 528 529 if (LDST_P_EQ_U(instr)) /* U = P */ 530 eaddr += 4; 531 532 /* 533 * For alignment faults on the ARM922T/ARM920T the MMU makes 534 * the FSR (and hence addr) equal to the updated base address 535 * of the multiple access rather than the restored value. 536 * Switch this message off if we've got a ARM92[02], otherwise 537 * [ls]dm alignment faults are noisy! 538 */ 539 #if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T) 540 /* 541 * This is a "hint" - we already have eaddr worked out by the 542 * processor for us. 543 */ 544 if (addr != eaddr) { 545 pr_err("LDMSTM: PC = %08lx, instr = %08lx, " 546 "addr = %08lx, eaddr = %08lx\n", 547 instruction_pointer(regs), instr, addr, eaddr); 548 show_regs(regs); 549 } 550 #endif 551 552 if (user_mode(regs)) { 553 unsigned int __ua_flags = uaccess_save_and_enable(); 554 for (regbits = REGMASK_BITS(instr), rd = 0; regbits; 555 regbits >>= 1, rd += 1) 556 if (regbits & 1) { 557 if (LDST_L_BIT(instr)) { 558 unsigned int val; 559 get32t_unaligned_check(val, eaddr); 560 regs->uregs[rd] = val; 561 } else 562 put32t_unaligned_check(regs->uregs[rd], eaddr); 563 eaddr += 4; 564 } 565 uaccess_restore(__ua_flags); 566 } else { 567 for (regbits = REGMASK_BITS(instr), rd = 0; regbits; 568 regbits >>= 1, rd += 1) 569 if (regbits & 1) { 570 if (LDST_L_BIT(instr)) { 571 unsigned int val; 572 get32_unaligned_check(val, eaddr); 573 regs->uregs[rd] = val; 574 } else 575 put32_unaligned_check(regs->uregs[rd], eaddr); 576 eaddr += 4; 577 } 578 } 579 580 if (LDST_W_BIT(instr)) 581 regs->uregs[rn] = newaddr; 582 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15))) 583 regs->ARM_pc -= correction; 584 return TYPE_DONE; 585 586 fault: 587 regs->ARM_pc -= correction; 588 return TYPE_FAULT; 589 590 bad: 591 pr_err("Alignment trap: not handling ldm with s-bit set\n"); 592 return TYPE_ERROR; 593 } 594 595 /* 596 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so 597 * we can reuse ARM userland alignment fault fixups for Thumb. 598 * 599 * This implementation was initially based on the algorithm found in 600 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same 601 * to convert only Thumb ld/st instruction forms to equivalent ARM forms. 602 * 603 * NOTES: 604 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections. 605 * 2. If for some reason we're passed an non-ld/st Thumb instruction to 606 * decode, we return 0xdeadc0de. This should never happen under normal 607 * circumstances but if it does, we've got other problems to deal with 608 * elsewhere and we obviously can't fix those problems here. 609 */ 610 611 static unsigned long 612 thumb2arm(u16 tinstr) 613 { 614 u32 L = (tinstr & (1<<11)) >> 11; 615 616 switch ((tinstr & 0xf800) >> 11) { 617 /* 6.5.1 Format 1: */ 618 case 0x6000 >> 11: /* 7.1.52 STR(1) */ 619 case 0x6800 >> 11: /* 7.1.26 LDR(1) */ 620 case 0x7000 >> 11: /* 7.1.55 STRB(1) */ 621 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */ 622 return 0xe5800000 | 623 ((tinstr & (1<<12)) << (22-12)) | /* fixup */ 624 (L<<20) | /* L==1? */ 625 ((tinstr & (7<<0)) << (12-0)) | /* Rd */ 626 ((tinstr & (7<<3)) << (16-3)) | /* Rn */ 627 ((tinstr & (31<<6)) >> /* immed_5 */ 628 (6 - ((tinstr & (1<<12)) ? 0 : 2))); 629 case 0x8000 >> 11: /* 7.1.57 STRH(1) */ 630 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */ 631 return 0xe1c000b0 | 632 (L<<20) | /* L==1? */ 633 ((tinstr & (7<<0)) << (12-0)) | /* Rd */ 634 ((tinstr & (7<<3)) << (16-3)) | /* Rn */ 635 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */ 636 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */ 637 638 /* 6.5.1 Format 2: */ 639 case 0x5000 >> 11: 640 case 0x5800 >> 11: 641 { 642 static const u32 subset[8] = { 643 0xe7800000, /* 7.1.53 STR(2) */ 644 0xe18000b0, /* 7.1.58 STRH(2) */ 645 0xe7c00000, /* 7.1.56 STRB(2) */ 646 0xe19000d0, /* 7.1.34 LDRSB */ 647 0xe7900000, /* 7.1.27 LDR(2) */ 648 0xe19000b0, /* 7.1.33 LDRH(2) */ 649 0xe7d00000, /* 7.1.31 LDRB(2) */ 650 0xe19000f0 /* 7.1.35 LDRSH */ 651 }; 652 return subset[(tinstr & (7<<9)) >> 9] | 653 ((tinstr & (7<<0)) << (12-0)) | /* Rd */ 654 ((tinstr & (7<<3)) << (16-3)) | /* Rn */ 655 ((tinstr & (7<<6)) >> (6-0)); /* Rm */ 656 } 657 658 /* 6.5.1 Format 3: */ 659 case 0x4800 >> 11: /* 7.1.28 LDR(3) */ 660 /* NOTE: This case is not technically possible. We're 661 * loading 32-bit memory data via PC relative 662 * addressing mode. So we can and should eliminate 663 * this case. But I'll leave it here for now. 664 */ 665 return 0xe59f0000 | 666 ((tinstr & (7<<8)) << (12-8)) | /* Rd */ 667 ((tinstr & 255) << (2-0)); /* immed_8 */ 668 669 /* 6.5.1 Format 4: */ 670 case 0x9000 >> 11: /* 7.1.54 STR(3) */ 671 case 0x9800 >> 11: /* 7.1.29 LDR(4) */ 672 return 0xe58d0000 | 673 (L<<20) | /* L==1? */ 674 ((tinstr & (7<<8)) << (12-8)) | /* Rd */ 675 ((tinstr & 255) << 2); /* immed_8 */ 676 677 /* 6.6.1 Format 1: */ 678 case 0xc000 >> 11: /* 7.1.51 STMIA */ 679 case 0xc800 >> 11: /* 7.1.25 LDMIA */ 680 { 681 u32 Rn = (tinstr & (7<<8)) >> 8; 682 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21; 683 684 return 0xe8800000 | W | (L<<20) | (Rn<<16) | 685 (tinstr&255); 686 } 687 688 /* 6.6.1 Format 2: */ 689 case 0xb000 >> 11: /* 7.1.48 PUSH */ 690 case 0xb800 >> 11: /* 7.1.47 POP */ 691 if ((tinstr & (3 << 9)) == 0x0400) { 692 static const u32 subset[4] = { 693 0xe92d0000, /* STMDB sp!,{registers} */ 694 0xe92d4000, /* STMDB sp!,{registers,lr} */ 695 0xe8bd0000, /* LDMIA sp!,{registers} */ 696 0xe8bd8000 /* LDMIA sp!,{registers,pc} */ 697 }; 698 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] | 699 (tinstr & 255); /* register_list */ 700 } 701 /* Else fall through for illegal instruction case */ 702 703 default: 704 return BAD_INSTR; 705 } 706 } 707 708 /* 709 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction 710 * handlable by ARM alignment handler, also find the corresponding handler, 711 * so that we can reuse ARM userland alignment fault fixups for Thumb. 712 * 713 * @pinstr: original Thumb-2 instruction; returns new handlable instruction 714 * @regs: register context. 715 * @poffset: return offset from faulted addr for later writeback 716 * 717 * NOTES: 718 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections. 719 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt) 720 */ 721 static void * 722 do_alignment_t32_to_handler(unsigned long *pinstr, struct pt_regs *regs, 723 union offset_union *poffset) 724 { 725 unsigned long instr = *pinstr; 726 u16 tinst1 = (instr >> 16) & 0xffff; 727 u16 tinst2 = instr & 0xffff; 728 729 switch (tinst1 & 0xffe0) { 730 /* A6.3.5 Load/Store multiple */ 731 case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */ 732 case 0xe8a0: /* ...above writeback version */ 733 case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */ 734 case 0xe920: /* ...above writeback version */ 735 /* no need offset decision since handler calculates it */ 736 return do_alignment_ldmstm; 737 738 case 0xf840: /* POP/PUSH T3 (single register) */ 739 if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) { 740 u32 L = !!(LDST_L_BIT(instr)); 741 const u32 subset[2] = { 742 0xe92d0000, /* STMDB sp!,{registers} */ 743 0xe8bd0000, /* LDMIA sp!,{registers} */ 744 }; 745 *pinstr = subset[L] | (1<<RD_BITS(instr)); 746 return do_alignment_ldmstm; 747 } 748 /* Else fall through for illegal instruction case */ 749 break; 750 751 /* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */ 752 case 0xe860: 753 case 0xe960: 754 case 0xe8e0: 755 case 0xe9e0: 756 poffset->un = (tinst2 & 0xff) << 2; 757 case 0xe940: 758 case 0xe9c0: 759 return do_alignment_ldrdstrd; 760 761 /* 762 * No need to handle load/store instructions up to word size 763 * since ARMv6 and later CPUs can perform unaligned accesses. 764 */ 765 default: 766 break; 767 } 768 return NULL; 769 } 770 771 static int 772 do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 773 { 774 union offset_union uninitialized_var(offset); 775 unsigned long instr = 0, instrptr; 776 int (*handler)(unsigned long addr, unsigned long instr, struct pt_regs *regs); 777 unsigned int type; 778 unsigned int fault; 779 u16 tinstr = 0; 780 int isize = 4; 781 int thumb2_32b = 0; 782 783 if (interrupts_enabled(regs)) 784 local_irq_enable(); 785 786 instrptr = instruction_pointer(regs); 787 788 if (thumb_mode(regs)) { 789 u16 *ptr = (u16 *)(instrptr & ~1); 790 fault = probe_kernel_address(ptr, tinstr); 791 tinstr = __mem_to_opcode_thumb16(tinstr); 792 if (!fault) { 793 if (cpu_architecture() >= CPU_ARCH_ARMv7 && 794 IS_T32(tinstr)) { 795 /* Thumb-2 32-bit */ 796 u16 tinst2 = 0; 797 fault = probe_kernel_address(ptr + 1, tinst2); 798 tinst2 = __mem_to_opcode_thumb16(tinst2); 799 instr = __opcode_thumb32_compose(tinstr, tinst2); 800 thumb2_32b = 1; 801 } else { 802 isize = 2; 803 instr = thumb2arm(tinstr); 804 } 805 } 806 } else { 807 fault = probe_kernel_address((void *)instrptr, instr); 808 instr = __mem_to_opcode_arm(instr); 809 } 810 811 if (fault) { 812 type = TYPE_FAULT; 813 goto bad_or_fault; 814 } 815 816 if (user_mode(regs)) 817 goto user; 818 819 ai_sys += 1; 820 ai_sys_last_pc = (void *)instruction_pointer(regs); 821 822 fixup: 823 824 regs->ARM_pc += isize; 825 826 switch (CODING_BITS(instr)) { 827 case 0x00000000: /* 3.13.4 load/store instruction extensions */ 828 if (LDSTHD_I_BIT(instr)) 829 offset.un = (instr & 0xf00) >> 4 | (instr & 15); 830 else 831 offset.un = regs->uregs[RM_BITS(instr)]; 832 833 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */ 834 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */ 835 handler = do_alignment_ldrhstrh; 836 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */ 837 (instr & 0x001000f0) == 0x000000f0) /* STRD */ 838 handler = do_alignment_ldrdstrd; 839 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */ 840 goto swp; 841 else 842 goto bad; 843 break; 844 845 case 0x04000000: /* ldr or str immediate */ 846 if (COND_BITS(instr) == 0xf0000000) /* NEON VLDn, VSTn */ 847 goto bad; 848 offset.un = OFFSET_BITS(instr); 849 handler = do_alignment_ldrstr; 850 break; 851 852 case 0x06000000: /* ldr or str register */ 853 offset.un = regs->uregs[RM_BITS(instr)]; 854 855 if (IS_SHIFT(instr)) { 856 unsigned int shiftval = SHIFT_BITS(instr); 857 858 switch(SHIFT_TYPE(instr)) { 859 case SHIFT_LSL: 860 offset.un <<= shiftval; 861 break; 862 863 case SHIFT_LSR: 864 offset.un >>= shiftval; 865 break; 866 867 case SHIFT_ASR: 868 offset.sn >>= shiftval; 869 break; 870 871 case SHIFT_RORRRX: 872 if (shiftval == 0) { 873 offset.un >>= 1; 874 if (regs->ARM_cpsr & PSR_C_BIT) 875 offset.un |= 1 << 31; 876 } else 877 offset.un = offset.un >> shiftval | 878 offset.un << (32 - shiftval); 879 break; 880 } 881 } 882 handler = do_alignment_ldrstr; 883 break; 884 885 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */ 886 if (thumb2_32b) { 887 offset.un = 0; 888 handler = do_alignment_t32_to_handler(&instr, regs, &offset); 889 } else { 890 offset.un = 0; 891 handler = do_alignment_ldmstm; 892 } 893 break; 894 895 default: 896 goto bad; 897 } 898 899 if (!handler) 900 goto bad; 901 type = handler(addr, instr, regs); 902 903 if (type == TYPE_ERROR || type == TYPE_FAULT) { 904 regs->ARM_pc -= isize; 905 goto bad_or_fault; 906 } 907 908 if (type == TYPE_LDST) 909 do_alignment_finish_ldst(addr, instr, regs, offset); 910 911 return 0; 912 913 bad_or_fault: 914 if (type == TYPE_ERROR) 915 goto bad; 916 /* 917 * We got a fault - fix it up, or die. 918 */ 919 do_bad_area(addr, fsr, regs); 920 return 0; 921 922 swp: 923 pr_err("Alignment trap: not handling swp instruction\n"); 924 925 bad: 926 /* 927 * Oops, we didn't handle the instruction. 928 */ 929 pr_err("Alignment trap: not handling instruction " 930 "%0*lx at [<%08lx>]\n", 931 isize << 1, 932 isize == 2 ? tinstr : instr, instrptr); 933 ai_skipped += 1; 934 return 1; 935 936 user: 937 ai_user += 1; 938 939 if (ai_usermode & UM_WARN) 940 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*lx " 941 "Address=0x%08lx FSR 0x%03x\n", current->comm, 942 task_pid_nr(current), instrptr, 943 isize << 1, 944 isize == 2 ? tinstr : instr, 945 addr, fsr); 946 947 if (ai_usermode & UM_FIXUP) 948 goto fixup; 949 950 if (ai_usermode & UM_SIGNAL) { 951 siginfo_t si; 952 953 clear_siginfo(&si); 954 si.si_signo = SIGBUS; 955 si.si_errno = 0; 956 si.si_code = BUS_ADRALN; 957 si.si_addr = (void __user *)addr; 958 959 force_sig_info(si.si_signo, &si, current); 960 } else { 961 /* 962 * We're about to disable the alignment trap and return to 963 * user space. But if an interrupt occurs before actually 964 * reaching user space, then the IRQ vector entry code will 965 * notice that we were still in kernel space and therefore 966 * the alignment trap won't be re-enabled in that case as it 967 * is presumed to be always on from kernel space. 968 * Let's prevent that race by disabling interrupts here (they 969 * are disabled on the way back to user space anyway in 970 * entry-common.S) and disable the alignment trap only if 971 * there is no work pending for this thread. 972 */ 973 raw_local_irq_disable(); 974 if (!(current_thread_info()->flags & _TIF_WORK_MASK)) 975 set_cr(cr_no_alignment); 976 } 977 978 return 0; 979 } 980 981 static int __init noalign_setup(char *__unused) 982 { 983 set_cr(__clear_cr(CR_A)); 984 return 1; 985 } 986 __setup("noalign", noalign_setup); 987 988 /* 989 * This needs to be done after sysctl_init, otherwise sys/ will be 990 * overwritten. Actually, this shouldn't be in sys/ at all since 991 * it isn't a sysctl, and it doesn't contain sysctl information. 992 * We now locate it in /proc/cpu/alignment instead. 993 */ 994 static int __init alignment_init(void) 995 { 996 #ifdef CONFIG_PROC_FS 997 struct proc_dir_entry *res; 998 999 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL, 1000 &alignment_proc_fops); 1001 if (!res) 1002 return -ENOMEM; 1003 #endif 1004 1005 if (cpu_is_v6_unaligned()) { 1006 set_cr(__clear_cr(CR_A)); 1007 ai_usermode = safe_usermode(ai_usermode, false); 1008 } 1009 1010 cr_no_alignment = get_cr() & ~CR_A; 1011 1012 hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN, 1013 "alignment exception"); 1014 1015 /* 1016 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section 1017 * fault, not as alignment error. 1018 * 1019 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is 1020 * needed. 1021 */ 1022 if (cpu_architecture() <= CPU_ARCH_ARMv6) { 1023 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN, 1024 "alignment exception"); 1025 } 1026 1027 return 0; 1028 } 1029 1030 fs_initcall(alignment_init); 1031