1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/arch/arm/mm/alignment.c 4 * 5 * Copyright (C) 1995 Linus Torvalds 6 * Modifications for ARM processor (c) 1995-2001 Russell King 7 * Thumb alignment fault fixups (c) 2004 MontaVista Software, Inc. 8 * - Adapted from gdb/sim/arm/thumbemu.c -- Thumb instruction emulation. 9 * Copyright (C) 1996, Cygnus Software Technologies Ltd. 10 */ 11 #include <linux/moduleparam.h> 12 #include <linux/compiler.h> 13 #include <linux/kernel.h> 14 #include <linux/sched/debug.h> 15 #include <linux/errno.h> 16 #include <linux/string.h> 17 #include <linux/proc_fs.h> 18 #include <linux/seq_file.h> 19 #include <linux/init.h> 20 #include <linux/sched/signal.h> 21 #include <linux/uaccess.h> 22 23 #include <asm/cp15.h> 24 #include <asm/system_info.h> 25 #include <asm/unaligned.h> 26 #include <asm/opcodes.h> 27 28 #include "fault.h" 29 #include "mm.h" 30 31 /* 32 * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998 33 * /proc/sys/debug/alignment, modified and integrated into 34 * Linux 2.1 by Russell King 35 * 36 * Speed optimisations and better fault handling by Russell King. 37 * 38 * *** NOTE *** 39 * This code is not portable to processors with late data abort handling. 40 */ 41 #define CODING_BITS(i) (i & 0x0e000000) 42 #define COND_BITS(i) (i & 0xf0000000) 43 44 #define LDST_I_BIT(i) (i & (1 << 26)) /* Immediate constant */ 45 #define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */ 46 #define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */ 47 #define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */ 48 #define LDST_L_BIT(i) (i & (1 << 20)) /* Load */ 49 50 #define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0) 51 52 #define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */ 53 #define LDM_S_BIT(i) (i & (1 << 22)) /* write CPSR from SPSR */ 54 55 #define RN_BITS(i) ((i >> 16) & 15) /* Rn */ 56 #define RD_BITS(i) ((i >> 12) & 15) /* Rd */ 57 #define RM_BITS(i) (i & 15) /* Rm */ 58 59 #define REGMASK_BITS(i) (i & 0xffff) 60 #define OFFSET_BITS(i) (i & 0x0fff) 61 62 #define IS_SHIFT(i) (i & 0x0ff0) 63 #define SHIFT_BITS(i) ((i >> 7) & 0x1f) 64 #define SHIFT_TYPE(i) (i & 0x60) 65 #define SHIFT_LSL 0x00 66 #define SHIFT_LSR 0x20 67 #define SHIFT_ASR 0x40 68 #define SHIFT_RORRRX 0x60 69 70 #define BAD_INSTR 0xdeadc0de 71 72 /* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */ 73 #define IS_T32(hi16) \ 74 (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800)) 75 76 static unsigned long ai_user; 77 static unsigned long ai_sys; 78 static void *ai_sys_last_pc; 79 static unsigned long ai_skipped; 80 static unsigned long ai_half; 81 static unsigned long ai_word; 82 static unsigned long ai_dword; 83 static unsigned long ai_multi; 84 static int ai_usermode; 85 static unsigned long cr_no_alignment; 86 87 core_param(alignment, ai_usermode, int, 0600); 88 89 #define UM_WARN (1 << 0) 90 #define UM_FIXUP (1 << 1) 91 #define UM_SIGNAL (1 << 2) 92 93 /* Return true if and only if the ARMv6 unaligned access model is in use. */ 94 static bool cpu_is_v6_unaligned(void) 95 { 96 return cpu_architecture() >= CPU_ARCH_ARMv6 && get_cr() & CR_U; 97 } 98 99 static int safe_usermode(int new_usermode, bool warn) 100 { 101 /* 102 * ARMv6 and later CPUs can perform unaligned accesses for 103 * most single load and store instructions up to word size. 104 * LDM, STM, LDRD and STRD still need to be handled. 105 * 106 * Ignoring the alignment fault is not an option on these 107 * CPUs since we spin re-faulting the instruction without 108 * making any progress. 109 */ 110 if (cpu_is_v6_unaligned() && !(new_usermode & (UM_FIXUP | UM_SIGNAL))) { 111 new_usermode |= UM_FIXUP; 112 113 if (warn) 114 pr_warn("alignment: ignoring faults is unsafe on this CPU. Defaulting to fixup mode.\n"); 115 } 116 117 return new_usermode; 118 } 119 120 #ifdef CONFIG_PROC_FS 121 static const char *usermode_action[] = { 122 "ignored", 123 "warn", 124 "fixup", 125 "fixup+warn", 126 "signal", 127 "signal+warn" 128 }; 129 130 static int alignment_proc_show(struct seq_file *m, void *v) 131 { 132 seq_printf(m, "User:\t\t%lu\n", ai_user); 133 seq_printf(m, "System:\t\t%lu (%pS)\n", ai_sys, ai_sys_last_pc); 134 seq_printf(m, "Skipped:\t%lu\n", ai_skipped); 135 seq_printf(m, "Half:\t\t%lu\n", ai_half); 136 seq_printf(m, "Word:\t\t%lu\n", ai_word); 137 if (cpu_architecture() >= CPU_ARCH_ARMv5TE) 138 seq_printf(m, "DWord:\t\t%lu\n", ai_dword); 139 seq_printf(m, "Multi:\t\t%lu\n", ai_multi); 140 seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode, 141 usermode_action[ai_usermode]); 142 143 return 0; 144 } 145 146 static int alignment_proc_open(struct inode *inode, struct file *file) 147 { 148 return single_open(file, alignment_proc_show, NULL); 149 } 150 151 static ssize_t alignment_proc_write(struct file *file, const char __user *buffer, 152 size_t count, loff_t *pos) 153 { 154 char mode; 155 156 if (count > 0) { 157 if (get_user(mode, buffer)) 158 return -EFAULT; 159 if (mode >= '0' && mode <= '5') 160 ai_usermode = safe_usermode(mode - '0', true); 161 } 162 return count; 163 } 164 165 static const struct proc_ops alignment_proc_ops = { 166 .proc_open = alignment_proc_open, 167 .proc_read = seq_read, 168 .proc_lseek = seq_lseek, 169 .proc_release = single_release, 170 .proc_write = alignment_proc_write, 171 }; 172 #endif /* CONFIG_PROC_FS */ 173 174 union offset_union { 175 unsigned long un; 176 signed long sn; 177 }; 178 179 #define TYPE_ERROR 0 180 #define TYPE_FAULT 1 181 #define TYPE_LDST 2 182 #define TYPE_DONE 3 183 184 #ifdef __ARMEB__ 185 #define BE 1 186 #define FIRST_BYTE_16 "mov %1, %1, ror #8\n" 187 #define FIRST_BYTE_32 "mov %1, %1, ror #24\n" 188 #define NEXT_BYTE "ror #24" 189 #else 190 #define BE 0 191 #define FIRST_BYTE_16 192 #define FIRST_BYTE_32 193 #define NEXT_BYTE "lsr #8" 194 #endif 195 196 #define __get8_unaligned_check(ins,val,addr,err) \ 197 __asm__( \ 198 ARM( "1: "ins" %1, [%2], #1\n" ) \ 199 THUMB( "1: "ins" %1, [%2]\n" ) \ 200 THUMB( " add %2, %2, #1\n" ) \ 201 "2:\n" \ 202 " .pushsection .text.fixup,\"ax\"\n" \ 203 " .align 2\n" \ 204 "3: mov %0, #1\n" \ 205 " b 2b\n" \ 206 " .popsection\n" \ 207 " .pushsection __ex_table,\"a\"\n" \ 208 " .align 3\n" \ 209 " .long 1b, 3b\n" \ 210 " .popsection\n" \ 211 : "=r" (err), "=&r" (val), "=r" (addr) \ 212 : "0" (err), "2" (addr)) 213 214 #define __get16_unaligned_check(ins,val,addr) \ 215 do { \ 216 unsigned int err = 0, v, a = addr; \ 217 __get8_unaligned_check(ins,v,a,err); \ 218 val = v << ((BE) ? 8 : 0); \ 219 __get8_unaligned_check(ins,v,a,err); \ 220 val |= v << ((BE) ? 0 : 8); \ 221 if (err) \ 222 goto fault; \ 223 } while (0) 224 225 #define get16_unaligned_check(val,addr) \ 226 __get16_unaligned_check("ldrb",val,addr) 227 228 #define get16t_unaligned_check(val,addr) \ 229 __get16_unaligned_check("ldrbt",val,addr) 230 231 #define __get32_unaligned_check(ins,val,addr) \ 232 do { \ 233 unsigned int err = 0, v, a = addr; \ 234 __get8_unaligned_check(ins,v,a,err); \ 235 val = v << ((BE) ? 24 : 0); \ 236 __get8_unaligned_check(ins,v,a,err); \ 237 val |= v << ((BE) ? 16 : 8); \ 238 __get8_unaligned_check(ins,v,a,err); \ 239 val |= v << ((BE) ? 8 : 16); \ 240 __get8_unaligned_check(ins,v,a,err); \ 241 val |= v << ((BE) ? 0 : 24); \ 242 if (err) \ 243 goto fault; \ 244 } while (0) 245 246 #define get32_unaligned_check(val,addr) \ 247 __get32_unaligned_check("ldrb",val,addr) 248 249 #define get32t_unaligned_check(val,addr) \ 250 __get32_unaligned_check("ldrbt",val,addr) 251 252 #define __put16_unaligned_check(ins,val,addr) \ 253 do { \ 254 unsigned int err = 0, v = val, a = addr; \ 255 __asm__( FIRST_BYTE_16 \ 256 ARM( "1: "ins" %1, [%2], #1\n" ) \ 257 THUMB( "1: "ins" %1, [%2]\n" ) \ 258 THUMB( " add %2, %2, #1\n" ) \ 259 " mov %1, %1, "NEXT_BYTE"\n" \ 260 "2: "ins" %1, [%2]\n" \ 261 "3:\n" \ 262 " .pushsection .text.fixup,\"ax\"\n" \ 263 " .align 2\n" \ 264 "4: mov %0, #1\n" \ 265 " b 3b\n" \ 266 " .popsection\n" \ 267 " .pushsection __ex_table,\"a\"\n" \ 268 " .align 3\n" \ 269 " .long 1b, 4b\n" \ 270 " .long 2b, 4b\n" \ 271 " .popsection\n" \ 272 : "=r" (err), "=&r" (v), "=&r" (a) \ 273 : "0" (err), "1" (v), "2" (a)); \ 274 if (err) \ 275 goto fault; \ 276 } while (0) 277 278 #define put16_unaligned_check(val,addr) \ 279 __put16_unaligned_check("strb",val,addr) 280 281 #define put16t_unaligned_check(val,addr) \ 282 __put16_unaligned_check("strbt",val,addr) 283 284 #define __put32_unaligned_check(ins,val,addr) \ 285 do { \ 286 unsigned int err = 0, v = val, a = addr; \ 287 __asm__( FIRST_BYTE_32 \ 288 ARM( "1: "ins" %1, [%2], #1\n" ) \ 289 THUMB( "1: "ins" %1, [%2]\n" ) \ 290 THUMB( " add %2, %2, #1\n" ) \ 291 " mov %1, %1, "NEXT_BYTE"\n" \ 292 ARM( "2: "ins" %1, [%2], #1\n" ) \ 293 THUMB( "2: "ins" %1, [%2]\n" ) \ 294 THUMB( " add %2, %2, #1\n" ) \ 295 " mov %1, %1, "NEXT_BYTE"\n" \ 296 ARM( "3: "ins" %1, [%2], #1\n" ) \ 297 THUMB( "3: "ins" %1, [%2]\n" ) \ 298 THUMB( " add %2, %2, #1\n" ) \ 299 " mov %1, %1, "NEXT_BYTE"\n" \ 300 "4: "ins" %1, [%2]\n" \ 301 "5:\n" \ 302 " .pushsection .text.fixup,\"ax\"\n" \ 303 " .align 2\n" \ 304 "6: mov %0, #1\n" \ 305 " b 5b\n" \ 306 " .popsection\n" \ 307 " .pushsection __ex_table,\"a\"\n" \ 308 " .align 3\n" \ 309 " .long 1b, 6b\n" \ 310 " .long 2b, 6b\n" \ 311 " .long 3b, 6b\n" \ 312 " .long 4b, 6b\n" \ 313 " .popsection\n" \ 314 : "=r" (err), "=&r" (v), "=&r" (a) \ 315 : "0" (err), "1" (v), "2" (a)); \ 316 if (err) \ 317 goto fault; \ 318 } while (0) 319 320 #define put32_unaligned_check(val,addr) \ 321 __put32_unaligned_check("strb", val, addr) 322 323 #define put32t_unaligned_check(val,addr) \ 324 __put32_unaligned_check("strbt", val, addr) 325 326 static void 327 do_alignment_finish_ldst(unsigned long addr, u32 instr, struct pt_regs *regs, union offset_union offset) 328 { 329 if (!LDST_U_BIT(instr)) 330 offset.un = -offset.un; 331 332 if (!LDST_P_BIT(instr)) 333 addr += offset.un; 334 335 if (!LDST_P_BIT(instr) || LDST_W_BIT(instr)) 336 regs->uregs[RN_BITS(instr)] = addr; 337 } 338 339 static int 340 do_alignment_ldrhstrh(unsigned long addr, u32 instr, struct pt_regs *regs) 341 { 342 unsigned int rd = RD_BITS(instr); 343 344 ai_half += 1; 345 346 if (user_mode(regs)) 347 goto user; 348 349 if (LDST_L_BIT(instr)) { 350 unsigned long val; 351 get16_unaligned_check(val, addr); 352 353 /* signed half-word? */ 354 if (instr & 0x40) 355 val = (signed long)((signed short) val); 356 357 regs->uregs[rd] = val; 358 } else 359 put16_unaligned_check(regs->uregs[rd], addr); 360 361 return TYPE_LDST; 362 363 user: 364 if (LDST_L_BIT(instr)) { 365 unsigned long val; 366 unsigned int __ua_flags = uaccess_save_and_enable(); 367 368 get16t_unaligned_check(val, addr); 369 uaccess_restore(__ua_flags); 370 371 /* signed half-word? */ 372 if (instr & 0x40) 373 val = (signed long)((signed short) val); 374 375 regs->uregs[rd] = val; 376 } else { 377 unsigned int __ua_flags = uaccess_save_and_enable(); 378 put16t_unaligned_check(regs->uregs[rd], addr); 379 uaccess_restore(__ua_flags); 380 } 381 382 return TYPE_LDST; 383 384 fault: 385 return TYPE_FAULT; 386 } 387 388 static int 389 do_alignment_ldrdstrd(unsigned long addr, u32 instr, struct pt_regs *regs) 390 { 391 unsigned int rd = RD_BITS(instr); 392 unsigned int rd2; 393 int load; 394 395 if ((instr & 0xfe000000) == 0xe8000000) { 396 /* ARMv7 Thumb-2 32-bit LDRD/STRD */ 397 rd2 = (instr >> 8) & 0xf; 398 load = !!(LDST_L_BIT(instr)); 399 } else if (((rd & 1) == 1) || (rd == 14)) 400 goto bad; 401 else { 402 load = ((instr & 0xf0) == 0xd0); 403 rd2 = rd + 1; 404 } 405 406 ai_dword += 1; 407 408 if (user_mode(regs)) 409 goto user; 410 411 if (load) { 412 unsigned long val; 413 get32_unaligned_check(val, addr); 414 regs->uregs[rd] = val; 415 get32_unaligned_check(val, addr + 4); 416 regs->uregs[rd2] = val; 417 } else { 418 put32_unaligned_check(regs->uregs[rd], addr); 419 put32_unaligned_check(regs->uregs[rd2], addr + 4); 420 } 421 422 return TYPE_LDST; 423 424 user: 425 if (load) { 426 unsigned long val, val2; 427 unsigned int __ua_flags = uaccess_save_and_enable(); 428 429 get32t_unaligned_check(val, addr); 430 get32t_unaligned_check(val2, addr + 4); 431 432 uaccess_restore(__ua_flags); 433 434 regs->uregs[rd] = val; 435 regs->uregs[rd2] = val2; 436 } else { 437 unsigned int __ua_flags = uaccess_save_and_enable(); 438 put32t_unaligned_check(regs->uregs[rd], addr); 439 put32t_unaligned_check(regs->uregs[rd2], addr + 4); 440 uaccess_restore(__ua_flags); 441 } 442 443 return TYPE_LDST; 444 bad: 445 return TYPE_ERROR; 446 fault: 447 return TYPE_FAULT; 448 } 449 450 static int 451 do_alignment_ldrstr(unsigned long addr, u32 instr, struct pt_regs *regs) 452 { 453 unsigned int rd = RD_BITS(instr); 454 455 ai_word += 1; 456 457 if ((!LDST_P_BIT(instr) && LDST_W_BIT(instr)) || user_mode(regs)) 458 goto trans; 459 460 if (LDST_L_BIT(instr)) { 461 unsigned int val; 462 get32_unaligned_check(val, addr); 463 regs->uregs[rd] = val; 464 } else 465 put32_unaligned_check(regs->uregs[rd], addr); 466 return TYPE_LDST; 467 468 trans: 469 if (LDST_L_BIT(instr)) { 470 unsigned int val; 471 unsigned int __ua_flags = uaccess_save_and_enable(); 472 get32t_unaligned_check(val, addr); 473 uaccess_restore(__ua_flags); 474 regs->uregs[rd] = val; 475 } else { 476 unsigned int __ua_flags = uaccess_save_and_enable(); 477 put32t_unaligned_check(regs->uregs[rd], addr); 478 uaccess_restore(__ua_flags); 479 } 480 return TYPE_LDST; 481 482 fault: 483 return TYPE_FAULT; 484 } 485 486 /* 487 * LDM/STM alignment handler. 488 * 489 * There are 4 variants of this instruction: 490 * 491 * B = rn pointer before instruction, A = rn pointer after instruction 492 * ------ increasing address -----> 493 * | | r0 | r1 | ... | rx | | 494 * PU = 01 B A 495 * PU = 11 B A 496 * PU = 00 A B 497 * PU = 10 A B 498 */ 499 static int 500 do_alignment_ldmstm(unsigned long addr, u32 instr, struct pt_regs *regs) 501 { 502 unsigned int rd, rn, correction, nr_regs, regbits; 503 unsigned long eaddr, newaddr; 504 505 if (LDM_S_BIT(instr)) 506 goto bad; 507 508 correction = 4; /* processor implementation defined */ 509 regs->ARM_pc += correction; 510 511 ai_multi += 1; 512 513 /* count the number of registers in the mask to be transferred */ 514 nr_regs = hweight16(REGMASK_BITS(instr)) * 4; 515 516 rn = RN_BITS(instr); 517 newaddr = eaddr = regs->uregs[rn]; 518 519 if (!LDST_U_BIT(instr)) 520 nr_regs = -nr_regs; 521 newaddr += nr_regs; 522 if (!LDST_U_BIT(instr)) 523 eaddr = newaddr; 524 525 if (LDST_P_EQ_U(instr)) /* U = P */ 526 eaddr += 4; 527 528 /* 529 * For alignment faults on the ARM922T/ARM920T the MMU makes 530 * the FSR (and hence addr) equal to the updated base address 531 * of the multiple access rather than the restored value. 532 * Switch this message off if we've got a ARM92[02], otherwise 533 * [ls]dm alignment faults are noisy! 534 */ 535 #if !(defined CONFIG_CPU_ARM922T) && !(defined CONFIG_CPU_ARM920T) 536 /* 537 * This is a "hint" - we already have eaddr worked out by the 538 * processor for us. 539 */ 540 if (addr != eaddr) { 541 pr_err("LDMSTM: PC = %08lx, instr = %08x, " 542 "addr = %08lx, eaddr = %08lx\n", 543 instruction_pointer(regs), instr, addr, eaddr); 544 show_regs(regs); 545 } 546 #endif 547 548 if (user_mode(regs)) { 549 unsigned int __ua_flags = uaccess_save_and_enable(); 550 for (regbits = REGMASK_BITS(instr), rd = 0; regbits; 551 regbits >>= 1, rd += 1) 552 if (regbits & 1) { 553 if (LDST_L_BIT(instr)) { 554 unsigned int val; 555 get32t_unaligned_check(val, eaddr); 556 regs->uregs[rd] = val; 557 } else 558 put32t_unaligned_check(regs->uregs[rd], eaddr); 559 eaddr += 4; 560 } 561 uaccess_restore(__ua_flags); 562 } else { 563 for (regbits = REGMASK_BITS(instr), rd = 0; regbits; 564 regbits >>= 1, rd += 1) 565 if (regbits & 1) { 566 if (LDST_L_BIT(instr)) { 567 unsigned int val; 568 get32_unaligned_check(val, eaddr); 569 regs->uregs[rd] = val; 570 } else 571 put32_unaligned_check(regs->uregs[rd], eaddr); 572 eaddr += 4; 573 } 574 } 575 576 if (LDST_W_BIT(instr)) 577 regs->uregs[rn] = newaddr; 578 if (!LDST_L_BIT(instr) || !(REGMASK_BITS(instr) & (1 << 15))) 579 regs->ARM_pc -= correction; 580 return TYPE_DONE; 581 582 fault: 583 regs->ARM_pc -= correction; 584 return TYPE_FAULT; 585 586 bad: 587 pr_err("Alignment trap: not handling ldm with s-bit set\n"); 588 return TYPE_ERROR; 589 } 590 591 /* 592 * Convert Thumb ld/st instruction forms to equivalent ARM instructions so 593 * we can reuse ARM userland alignment fault fixups for Thumb. 594 * 595 * This implementation was initially based on the algorithm found in 596 * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same 597 * to convert only Thumb ld/st instruction forms to equivalent ARM forms. 598 * 599 * NOTES: 600 * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections. 601 * 2. If for some reason we're passed an non-ld/st Thumb instruction to 602 * decode, we return 0xdeadc0de. This should never happen under normal 603 * circumstances but if it does, we've got other problems to deal with 604 * elsewhere and we obviously can't fix those problems here. 605 */ 606 607 static unsigned long 608 thumb2arm(u16 tinstr) 609 { 610 u32 L = (tinstr & (1<<11)) >> 11; 611 612 switch ((tinstr & 0xf800) >> 11) { 613 /* 6.5.1 Format 1: */ 614 case 0x6000 >> 11: /* 7.1.52 STR(1) */ 615 case 0x6800 >> 11: /* 7.1.26 LDR(1) */ 616 case 0x7000 >> 11: /* 7.1.55 STRB(1) */ 617 case 0x7800 >> 11: /* 7.1.30 LDRB(1) */ 618 return 0xe5800000 | 619 ((tinstr & (1<<12)) << (22-12)) | /* fixup */ 620 (L<<20) | /* L==1? */ 621 ((tinstr & (7<<0)) << (12-0)) | /* Rd */ 622 ((tinstr & (7<<3)) << (16-3)) | /* Rn */ 623 ((tinstr & (31<<6)) >> /* immed_5 */ 624 (6 - ((tinstr & (1<<12)) ? 0 : 2))); 625 case 0x8000 >> 11: /* 7.1.57 STRH(1) */ 626 case 0x8800 >> 11: /* 7.1.32 LDRH(1) */ 627 return 0xe1c000b0 | 628 (L<<20) | /* L==1? */ 629 ((tinstr & (7<<0)) << (12-0)) | /* Rd */ 630 ((tinstr & (7<<3)) << (16-3)) | /* Rn */ 631 ((tinstr & (7<<6)) >> (6-1)) | /* immed_5[2:0] */ 632 ((tinstr & (3<<9)) >> (9-8)); /* immed_5[4:3] */ 633 634 /* 6.5.1 Format 2: */ 635 case 0x5000 >> 11: 636 case 0x5800 >> 11: 637 { 638 static const u32 subset[8] = { 639 0xe7800000, /* 7.1.53 STR(2) */ 640 0xe18000b0, /* 7.1.58 STRH(2) */ 641 0xe7c00000, /* 7.1.56 STRB(2) */ 642 0xe19000d0, /* 7.1.34 LDRSB */ 643 0xe7900000, /* 7.1.27 LDR(2) */ 644 0xe19000b0, /* 7.1.33 LDRH(2) */ 645 0xe7d00000, /* 7.1.31 LDRB(2) */ 646 0xe19000f0 /* 7.1.35 LDRSH */ 647 }; 648 return subset[(tinstr & (7<<9)) >> 9] | 649 ((tinstr & (7<<0)) << (12-0)) | /* Rd */ 650 ((tinstr & (7<<3)) << (16-3)) | /* Rn */ 651 ((tinstr & (7<<6)) >> (6-0)); /* Rm */ 652 } 653 654 /* 6.5.1 Format 3: */ 655 case 0x4800 >> 11: /* 7.1.28 LDR(3) */ 656 /* NOTE: This case is not technically possible. We're 657 * loading 32-bit memory data via PC relative 658 * addressing mode. So we can and should eliminate 659 * this case. But I'll leave it here for now. 660 */ 661 return 0xe59f0000 | 662 ((tinstr & (7<<8)) << (12-8)) | /* Rd */ 663 ((tinstr & 255) << (2-0)); /* immed_8 */ 664 665 /* 6.5.1 Format 4: */ 666 case 0x9000 >> 11: /* 7.1.54 STR(3) */ 667 case 0x9800 >> 11: /* 7.1.29 LDR(4) */ 668 return 0xe58d0000 | 669 (L<<20) | /* L==1? */ 670 ((tinstr & (7<<8)) << (12-8)) | /* Rd */ 671 ((tinstr & 255) << 2); /* immed_8 */ 672 673 /* 6.6.1 Format 1: */ 674 case 0xc000 >> 11: /* 7.1.51 STMIA */ 675 case 0xc800 >> 11: /* 7.1.25 LDMIA */ 676 { 677 u32 Rn = (tinstr & (7<<8)) >> 8; 678 u32 W = ((L<<Rn) & (tinstr&255)) ? 0 : 1<<21; 679 680 return 0xe8800000 | W | (L<<20) | (Rn<<16) | 681 (tinstr&255); 682 } 683 684 /* 6.6.1 Format 2: */ 685 case 0xb000 >> 11: /* 7.1.48 PUSH */ 686 case 0xb800 >> 11: /* 7.1.47 POP */ 687 if ((tinstr & (3 << 9)) == 0x0400) { 688 static const u32 subset[4] = { 689 0xe92d0000, /* STMDB sp!,{registers} */ 690 0xe92d4000, /* STMDB sp!,{registers,lr} */ 691 0xe8bd0000, /* LDMIA sp!,{registers} */ 692 0xe8bd8000 /* LDMIA sp!,{registers,pc} */ 693 }; 694 return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] | 695 (tinstr & 255); /* register_list */ 696 } 697 fallthrough; /* for illegal instruction case */ 698 699 default: 700 return BAD_INSTR; 701 } 702 } 703 704 /* 705 * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction 706 * handlable by ARM alignment handler, also find the corresponding handler, 707 * so that we can reuse ARM userland alignment fault fixups for Thumb. 708 * 709 * @pinstr: original Thumb-2 instruction; returns new handlable instruction 710 * @regs: register context. 711 * @poffset: return offset from faulted addr for later writeback 712 * 713 * NOTES: 714 * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections. 715 * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt) 716 */ 717 static void * 718 do_alignment_t32_to_handler(u32 *pinstr, struct pt_regs *regs, 719 union offset_union *poffset) 720 { 721 u32 instr = *pinstr; 722 u16 tinst1 = (instr >> 16) & 0xffff; 723 u16 tinst2 = instr & 0xffff; 724 725 switch (tinst1 & 0xffe0) { 726 /* A6.3.5 Load/Store multiple */ 727 case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */ 728 case 0xe8a0: /* ...above writeback version */ 729 case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */ 730 case 0xe920: /* ...above writeback version */ 731 /* no need offset decision since handler calculates it */ 732 return do_alignment_ldmstm; 733 734 case 0xf840: /* POP/PUSH T3 (single register) */ 735 if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) { 736 u32 L = !!(LDST_L_BIT(instr)); 737 const u32 subset[2] = { 738 0xe92d0000, /* STMDB sp!,{registers} */ 739 0xe8bd0000, /* LDMIA sp!,{registers} */ 740 }; 741 *pinstr = subset[L] | (1<<RD_BITS(instr)); 742 return do_alignment_ldmstm; 743 } 744 /* Else fall through for illegal instruction case */ 745 break; 746 747 /* A6.3.6 Load/store double, STRD/LDRD(immed, lit, reg) */ 748 case 0xe860: 749 case 0xe960: 750 case 0xe8e0: 751 case 0xe9e0: 752 poffset->un = (tinst2 & 0xff) << 2; 753 fallthrough; 754 755 case 0xe940: 756 case 0xe9c0: 757 return do_alignment_ldrdstrd; 758 759 /* 760 * No need to handle load/store instructions up to word size 761 * since ARMv6 and later CPUs can perform unaligned accesses. 762 */ 763 default: 764 break; 765 } 766 return NULL; 767 } 768 769 static int alignment_get_arm(struct pt_regs *regs, u32 *ip, u32 *inst) 770 { 771 u32 instr = 0; 772 int fault; 773 774 if (user_mode(regs)) 775 fault = get_user(instr, ip); 776 else 777 fault = get_kernel_nofault(instr, ip); 778 779 *inst = __mem_to_opcode_arm(instr); 780 781 return fault; 782 } 783 784 static int alignment_get_thumb(struct pt_regs *regs, u16 *ip, u16 *inst) 785 { 786 u16 instr = 0; 787 int fault; 788 789 if (user_mode(regs)) 790 fault = get_user(instr, ip); 791 else 792 fault = get_kernel_nofault(instr, ip); 793 794 *inst = __mem_to_opcode_thumb16(instr); 795 796 return fault; 797 } 798 799 static int 800 do_alignment(unsigned long addr, unsigned int fsr, struct pt_regs *regs) 801 { 802 union offset_union offset; 803 unsigned long instrptr; 804 int (*handler)(unsigned long addr, u32 instr, struct pt_regs *regs); 805 unsigned int type; 806 u32 instr = 0; 807 u16 tinstr = 0; 808 int isize = 4; 809 int thumb2_32b = 0; 810 int fault; 811 812 if (interrupts_enabled(regs)) 813 local_irq_enable(); 814 815 instrptr = instruction_pointer(regs); 816 817 if (thumb_mode(regs)) { 818 u16 *ptr = (u16 *)(instrptr & ~1); 819 820 fault = alignment_get_thumb(regs, ptr, &tinstr); 821 if (!fault) { 822 if (cpu_architecture() >= CPU_ARCH_ARMv7 && 823 IS_T32(tinstr)) { 824 /* Thumb-2 32-bit */ 825 u16 tinst2; 826 fault = alignment_get_thumb(regs, ptr + 1, &tinst2); 827 instr = __opcode_thumb32_compose(tinstr, tinst2); 828 thumb2_32b = 1; 829 } else { 830 isize = 2; 831 instr = thumb2arm(tinstr); 832 } 833 } 834 } else { 835 fault = alignment_get_arm(regs, (void *)instrptr, &instr); 836 } 837 838 if (fault) { 839 type = TYPE_FAULT; 840 goto bad_or_fault; 841 } 842 843 if (user_mode(regs)) 844 goto user; 845 846 ai_sys += 1; 847 ai_sys_last_pc = (void *)instruction_pointer(regs); 848 849 fixup: 850 851 regs->ARM_pc += isize; 852 853 switch (CODING_BITS(instr)) { 854 case 0x00000000: /* 3.13.4 load/store instruction extensions */ 855 if (LDSTHD_I_BIT(instr)) 856 offset.un = (instr & 0xf00) >> 4 | (instr & 15); 857 else 858 offset.un = regs->uregs[RM_BITS(instr)]; 859 860 if ((instr & 0x000000f0) == 0x000000b0 || /* LDRH, STRH */ 861 (instr & 0x001000f0) == 0x001000f0) /* LDRSH */ 862 handler = do_alignment_ldrhstrh; 863 else if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */ 864 (instr & 0x001000f0) == 0x000000f0) /* STRD */ 865 handler = do_alignment_ldrdstrd; 866 else if ((instr & 0x01f00ff0) == 0x01000090) /* SWP */ 867 goto swp; 868 else 869 goto bad; 870 break; 871 872 case 0x04000000: /* ldr or str immediate */ 873 if (COND_BITS(instr) == 0xf0000000) /* NEON VLDn, VSTn */ 874 goto bad; 875 offset.un = OFFSET_BITS(instr); 876 handler = do_alignment_ldrstr; 877 break; 878 879 case 0x06000000: /* ldr or str register */ 880 offset.un = regs->uregs[RM_BITS(instr)]; 881 882 if (IS_SHIFT(instr)) { 883 unsigned int shiftval = SHIFT_BITS(instr); 884 885 switch(SHIFT_TYPE(instr)) { 886 case SHIFT_LSL: 887 offset.un <<= shiftval; 888 break; 889 890 case SHIFT_LSR: 891 offset.un >>= shiftval; 892 break; 893 894 case SHIFT_ASR: 895 offset.sn >>= shiftval; 896 break; 897 898 case SHIFT_RORRRX: 899 if (shiftval == 0) { 900 offset.un >>= 1; 901 if (regs->ARM_cpsr & PSR_C_BIT) 902 offset.un |= 1 << 31; 903 } else 904 offset.un = offset.un >> shiftval | 905 offset.un << (32 - shiftval); 906 break; 907 } 908 } 909 handler = do_alignment_ldrstr; 910 break; 911 912 case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */ 913 if (thumb2_32b) { 914 offset.un = 0; 915 handler = do_alignment_t32_to_handler(&instr, regs, &offset); 916 } else { 917 offset.un = 0; 918 handler = do_alignment_ldmstm; 919 } 920 break; 921 922 default: 923 goto bad; 924 } 925 926 if (!handler) 927 goto bad; 928 type = handler(addr, instr, regs); 929 930 if (type == TYPE_ERROR || type == TYPE_FAULT) { 931 regs->ARM_pc -= isize; 932 goto bad_or_fault; 933 } 934 935 if (type == TYPE_LDST) 936 do_alignment_finish_ldst(addr, instr, regs, offset); 937 938 return 0; 939 940 bad_or_fault: 941 if (type == TYPE_ERROR) 942 goto bad; 943 /* 944 * We got a fault - fix it up, or die. 945 */ 946 do_bad_area(addr, fsr, regs); 947 return 0; 948 949 swp: 950 pr_err("Alignment trap: not handling swp instruction\n"); 951 952 bad: 953 /* 954 * Oops, we didn't handle the instruction. 955 */ 956 pr_err("Alignment trap: not handling instruction " 957 "%0*x at [<%08lx>]\n", 958 isize << 1, 959 isize == 2 ? tinstr : instr, instrptr); 960 ai_skipped += 1; 961 return 1; 962 963 user: 964 ai_user += 1; 965 966 if (ai_usermode & UM_WARN) 967 printk("Alignment trap: %s (%d) PC=0x%08lx Instr=0x%0*x " 968 "Address=0x%08lx FSR 0x%03x\n", current->comm, 969 task_pid_nr(current), instrptr, 970 isize << 1, 971 isize == 2 ? tinstr : instr, 972 addr, fsr); 973 974 if (ai_usermode & UM_FIXUP) 975 goto fixup; 976 977 if (ai_usermode & UM_SIGNAL) { 978 force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)addr); 979 } else { 980 /* 981 * We're about to disable the alignment trap and return to 982 * user space. But if an interrupt occurs before actually 983 * reaching user space, then the IRQ vector entry code will 984 * notice that we were still in kernel space and therefore 985 * the alignment trap won't be re-enabled in that case as it 986 * is presumed to be always on from kernel space. 987 * Let's prevent that race by disabling interrupts here (they 988 * are disabled on the way back to user space anyway in 989 * entry-common.S) and disable the alignment trap only if 990 * there is no work pending for this thread. 991 */ 992 raw_local_irq_disable(); 993 if (!(current_thread_info()->flags & _TIF_WORK_MASK)) 994 set_cr(cr_no_alignment); 995 } 996 997 return 0; 998 } 999 1000 static int __init noalign_setup(char *__unused) 1001 { 1002 set_cr(__clear_cr(CR_A)); 1003 return 1; 1004 } 1005 __setup("noalign", noalign_setup); 1006 1007 /* 1008 * This needs to be done after sysctl_init, otherwise sys/ will be 1009 * overwritten. Actually, this shouldn't be in sys/ at all since 1010 * it isn't a sysctl, and it doesn't contain sysctl information. 1011 * We now locate it in /proc/cpu/alignment instead. 1012 */ 1013 static int __init alignment_init(void) 1014 { 1015 #ifdef CONFIG_PROC_FS 1016 struct proc_dir_entry *res; 1017 1018 res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL, 1019 &alignment_proc_ops); 1020 if (!res) 1021 return -ENOMEM; 1022 #endif 1023 1024 if (cpu_is_v6_unaligned()) { 1025 set_cr(__clear_cr(CR_A)); 1026 ai_usermode = safe_usermode(ai_usermode, false); 1027 } 1028 1029 cr_no_alignment = get_cr() & ~CR_A; 1030 1031 hook_fault_code(FAULT_CODE_ALIGNMENT, do_alignment, SIGBUS, BUS_ADRALN, 1032 "alignment exception"); 1033 1034 /* 1035 * ARMv6K and ARMv7 use fault status 3 (0b00011) as Access Flag section 1036 * fault, not as alignment error. 1037 * 1038 * TODO: handle ARMv6K properly. Runtime check for 'K' extension is 1039 * needed. 1040 */ 1041 if (cpu_architecture() <= CPU_ARCH_ARMv6) { 1042 hook_fault_code(3, do_alignment, SIGBUS, BUS_ADRALN, 1043 "alignment exception"); 1044 } 1045 1046 return 0; 1047 } 1048 1049 fs_initcall(alignment_init); 1050