개념 설명 전체 · v6.6 / arch/arm64/mm/fault.c
1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Based on arch/arm/mm/fault.c 4 * 5 * Copyright (C) 1995 Linus Torvalds 6 * Copyright (C) 1995-2004 Russell King 7 * Copyright (C) 2012 ARM Ltd. 8 */ 9 10 #include <linux/acpi.h> 11 #include <linux/bitfield.h> 12 #include <linux/extable.h> 13 #include <linux/kfence.h> 14 #include <linux/signal.h> 15 #include <linux/mm.h> 16 #include <linux/hardirq.h> 17 #include <linux/init.h> 18 #include <linux/kasan.h> 19 #include <linux/kprobes.h> 20 #include <linux/uaccess.h> 21 #include <linux/page-flags.h> 22 #include <linux/sched/signal.h> 23 #include <linux/sched/debug.h> 24 #include <linux/highmem.h> 25 #include <linux/perf_event.h> 26 #include <linux/preempt.h> 27 #include <linux/hugetlb.h> 28 29 #include <asm/acpi.h> 30 #include <asm/bug.h> 31 #include <asm/cmpxchg.h> 32 #include <asm/cpufeature.h> 33 #include <asm/efi.h> 34 #include <asm/exception.h> 35 #include <asm/daifflags.h> 36 #include <asm/debug-monitors.h> 37 #include <asm/esr.h> 38 #include <asm/kprobes.h> 39 #include <asm/mte.h> 40 #include <asm/processor.h> 41 #include <asm/sysreg.h> 42 #include <asm/system_misc.h> 43 #include <asm/tlbflush.h> 44 #include <asm/traps.h> 45 46 struct fault_info { 47 int (*fn)(unsigned long far, unsigned long esr, 48 struct pt_regs *regs); 49 int sig; 50 int code; 51 const char *name; 52 }; 53 54 static const struct fault_info fault_info[]; 55 static struct fault_info debug_fault_info[]; 56 57 static inline const struct fault_info *esr_to_fault_info(unsigned long esr) 58 { 59 return fault_info + (esr & ESR_ELx_FSC); 60 } 61 62 static inline const struct fault_info *esr_to_debug_fault_info(unsigned long esr) 63 { 64 return debug_fault_info + DBG_ESR_EVT(esr); 65 } 66 67 static void data_abort_decode(unsigned long esr) 68 { 69 unsigned long iss2 = ESR_ELx_ISS2(esr); 70 71 pr_alert("Data abort info:\n"); 72 73 if (esr & ESR_ELx_ISV) { 74 pr_alert(" Access size = %u byte(s)\n", 75 1U << ((esr & ESR_ELx_SAS) >> ESR_ELx_SAS_SHIFT)); 76 pr_alert(" SSE = %lu, SRT = %lu\n", 77 (esr & ESR_ELx_SSE) >> ESR_ELx_SSE_SHIFT, 78 (esr & ESR_ELx_SRT_MASK) >> ESR_ELx_SRT_SHIFT); 79 pr_alert(" SF = %lu, AR = %lu\n", 80 (esr & ESR_ELx_SF) >> ESR_ELx_SF_SHIFT, 81 (esr & ESR_ELx_AR) >> ESR_ELx_AR_SHIFT); 82 } else { 83 pr_alert(" ISV = 0, ISS = 0x%08lx, ISS2 = 0x%08lx\n", 84 esr & ESR_ELx_ISS_MASK, iss2); 85 } 86 87 pr_alert(" CM = %lu, WnR = %lu, TnD = %lu, TagAccess = %lu\n", 88 (esr & ESR_ELx_CM) >> ESR_ELx_CM_SHIFT, 89 (esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT, 90 (iss2 & ESR_ELx_TnD) >> ESR_ELx_TnD_SHIFT, 91 (iss2 & ESR_ELx_TagAccess) >> ESR_ELx_TagAccess_SHIFT); 92 93 pr_alert(" GCS = %ld, Overlay = %lu, DirtyBit = %lu, Xs = %llu\n", 94 (iss2 & ESR_ELx_GCS) >> ESR_ELx_GCS_SHIFT, 95 (iss2 & ESR_ELx_Overlay) >> ESR_ELx_Overlay_SHIFT, 96 (iss2 & ESR_ELx_DirtyBit) >> ESR_ELx_DirtyBit_SHIFT, 97 (iss2 & ESR_ELx_Xs_MASK) >> ESR_ELx_Xs_SHIFT); 98 } 99 100 static void mem_abort_decode(unsigned long esr) 101 { 102 pr_alert("Mem abort info:\n"); 103 104 pr_alert(" ESR = 0x%016lx\n", esr); 105 pr_alert(" EC = 0x%02lx: %s, IL = %u bits\n", 106 ESR_ELx_EC(esr), esr_get_class_string(esr), 107 (esr & ESR_ELx_IL) ? 32 : 16); 108 pr_alert(" SET = %lu, FnV = %lu\n", 109 (esr & ESR_ELx_SET_MASK) >> ESR_ELx_SET_SHIFT, 110 (esr & ESR_ELx_FnV) >> ESR_ELx_FnV_SHIFT); 111 pr_alert(" EA = %lu, S1PTW = %lu\n", 112 (esr & ESR_ELx_EA) >> ESR_ELx_EA_SHIFT, 113 (esr & ESR_ELx_S1PTW) >> ESR_ELx_S1PTW_SHIFT); 114 pr_alert(" FSC = 0x%02lx: %s\n", (esr & ESR_ELx_FSC), 115 esr_to_fault_info(esr)->name); 116 117 if (esr_is_data_abort(esr)) 118 data_abort_decode(esr); 119 } 120 121 static inline unsigned long mm_to_pgd_phys(struct mm_struct *mm) 122 { 123 /* Either init_pg_dir or swapper_pg_dir */ 124 if (mm == &init_mm) 125 return __pa_symbol(mm->pgd); 126 127 return (unsigned long)virt_to_phys(mm->pgd); 128 } 129 130 /* 131 * Dump out the page tables associated with 'addr' in the currently active mm. 132 */ 133 static void show_pte(unsigned long addr) 134 { 135 struct mm_struct *mm; 136 pgd_t *pgdp; 137 pgd_t pgd; 138 139 if (is_ttbr0_addr(addr)) { 140 /* TTBR0 */ 141 mm = current->active_mm; 142 if (mm == &init_mm) { 143 pr_alert("[%016lx] user address but active_mm is swapper\n", 144 addr); 145 return; 146 } 147 } else if (is_ttbr1_addr(addr)) { 148 /* TTBR1 */ 149 mm = &init_mm; 150 } else { 151 pr_alert("[%016lx] address between user and kernel address ranges\n", 152 addr); 153 return; 154 } 155 156 pr_alert("%s pgtable: %luk pages, %llu-bit VAs, pgdp=%016lx\n", 157 mm == &init_mm ? "swapper" : "user", PAGE_SIZE / SZ_1K, 158 vabits_actual, mm_to_pgd_phys(mm)); 159 pgdp = pgd_offset(mm, addr); 160 pgd = READ_ONCE(*pgdp); 161 pr_alert("[%016lx] pgd=%016llx", addr, pgd_val(pgd)); 162 163 do { 164 p4d_t *p4dp, p4d; 165 pud_t *pudp, pud; 166 pmd_t *pmdp, pmd; 167 pte_t *ptep, pte; 168 169 if (pgd_none(pgd) || pgd_bad(pgd)) 170 break; 171 172 p4dp = p4d_offset(pgdp, addr); 173 p4d = READ_ONCE(*p4dp); 174 pr_cont(", p4d=%016llx", p4d_val(p4d)); 175 if (p4d_none(p4d) || p4d_bad(p4d)) 176 break; 177 178 pudp = pud_offset(p4dp, addr); 179 pud = READ_ONCE(*pudp); 180 pr_cont(", pud=%016llx", pud_val(pud)); 181 if (pud_none(pud) || pud_bad(pud)) 182 break; 183 184 pmdp = pmd_offset(pudp, addr); 185 pmd = READ_ONCE(*pmdp); 186 pr_cont(", pmd=%016llx", pmd_val(pmd)); 187 if (pmd_none(pmd) || pmd_bad(pmd)) 188 break; 189 190 ptep = pte_offset_map(pmdp, addr); 191 if (!ptep) 192 break; 193 194 pte = READ_ONCE(*ptep); 195 pr_cont(", pte=%016llx", pte_val(pte)); 196 pte_unmap(ptep); 197 } while(0); 198 199 pr_cont("\n"); 200 } 201 202 /* 203 * This function sets the access flags (dirty, accessed), as well as write 204 * permission, and only to a more permissive setting. 205 * 206 * It needs to cope with hardware update of the accessed/dirty state by other 207 * agents in the system and can safely skip the __sync_icache_dcache() call as, 208 * like set_pte_at(), the PTE is never changed from no-exec to exec here. 209 * 210 * Returns whether or not the PTE actually changed. 211 */ 212 int ptep_set_access_flags(struct vm_area_struct *vma, 213 unsigned long address, pte_t *ptep, 214 pte_t entry, int dirty) 215 { 216 pteval_t old_pteval, pteval; 217 pte_t pte = READ_ONCE(*ptep); 218 219 if (pte_same(pte, entry)) 220 return 0; 221 222 /* only preserve the access flags and write permission */ 223 pte_val(entry) &= PTE_RDONLY | PTE_AF | PTE_WRITE | PTE_DIRTY; 224 225 /* 226 * Setting the flags must be done atomically to avoid racing with the 227 * hardware update of the access/dirty state. The PTE_RDONLY bit must 228 * be set to the most permissive (lowest value) of *ptep and entry 229 * (calculated as: a & b == ~(~a | ~b)). 230 */ 231 pte_val(entry) ^= PTE_RDONLY; 232 pteval = pte_val(pte); 233 do { 234 old_pteval = pteval; 235 pteval ^= PTE_RDONLY; 236 pteval |= pte_val(entry); 237 pteval ^= PTE_RDONLY; 238 pteval = cmpxchg_relaxed(&pte_val(*ptep), old_pteval, pteval); 239 } while (pteval != old_pteval); 240 241 /* Invalidate a stale read-only entry */ 242 if (dirty) 243 flush_tlb_page(vma, address); 244 return 1; 245 } 246 247 static bool is_el1_instruction_abort(unsigned long esr) 248 { 249 return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR; 250 } 251 252 static bool is_el1_data_abort(unsigned long esr) 253 { 254 return ESR_ELx_EC(esr) == ESR_ELx_EC_DABT_CUR; 255 } 256 257 static inline bool is_el1_permission_fault(unsigned long addr, unsigned long esr, 258 struct pt_regs *regs) 259 { 260 unsigned long fsc_type = esr & ESR_ELx_FSC_TYPE; 261 262 if (!is_el1_data_abort(esr) && !is_el1_instruction_abort(esr)) 263 return false; 264 265 if (fsc_type == ESR_ELx_FSC_PERM) 266 return true; 267 268 if (is_ttbr0_addr(addr) && system_uses_ttbr0_pan()) 269 return fsc_type == ESR_ELx_FSC_FAULT && 270 (regs->pstate & PSR_PAN_BIT); 271 272 return false; 273 } 274 275 static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr, 276 unsigned long esr, 277 struct pt_regs *regs) 278 { 279 unsigned long flags; 280 u64 par, dfsc; 281 282 if (!is_el1_data_abort(esr) || 283 (esr & ESR_ELx_FSC_TYPE) != ESR_ELx_FSC_FAULT) 284 return false; 285 286 local_irq_save(flags); 287 asm volatile("at s1e1r, %0" :: "r" (addr)); 288 isb(); 289 par = read_sysreg_par(); 290 local_irq_restore(flags); 291 292 /* 293 * If we now have a valid translation, treat the translation fault as 294 * spurious. 295 */ 296 if (!(par & SYS_PAR_EL1_F)) 297 return true; 298 299 /* 300 * If we got a different type of fault from the AT instruction, 301 * treat the translation fault as spurious. 302 */ 303 dfsc = FIELD_GET(SYS_PAR_EL1_FST, par); 304 return (dfsc & ESR_ELx_FSC_TYPE) != ESR_ELx_FSC_FAULT; 305 } 306 307 static void die_kernel_fault(const char *msg, unsigned long addr, 308 unsigned long esr, struct pt_regs *regs) 309 { 310 bust_spinlocks(1); 311 312 pr_alert("Unable to handle kernel %s at virtual address %016lx\n", msg, 313 addr); 314 315 kasan_non_canonical_hook(addr); 316 317 mem_abort_decode(esr); 318 319 show_pte(addr); 320 die("Oops", regs, esr); 321 bust_spinlocks(0); 322 make_task_dead(SIGKILL); 323 } 324 325 #ifdef CONFIG_KASAN_HW_TAGS 326 static void report_tag_fault(unsigned long addr, unsigned long esr, 327 struct pt_regs *regs) 328 { 329 /* 330 * SAS bits aren't set for all faults reported in EL1, so we can't 331 * find out access size. 332 */ 333 bool is_write = !!(esr & ESR_ELx_WNR); 334 kasan_report((void *)addr, 0, is_write, regs->pc); 335 } 336 #else 337 /* Tag faults aren't enabled without CONFIG_KASAN_HW_TAGS. */ 338 static inline void report_tag_fault(unsigned long addr, unsigned long esr, 339 struct pt_regs *regs) { } 340 #endif 341 342 static void do_tag_recovery(unsigned long addr, unsigned long esr, 343 struct pt_regs *regs) 344 { 345 346 report_tag_fault(addr, esr, regs); 347 348 /* 349 * Disable MTE Tag Checking on the local CPU for the current EL. 350 * It will be done lazily on the other CPUs when they will hit a 351 * tag fault. 352 */ 353 sysreg_clear_set(sctlr_el1, SCTLR_EL1_TCF_MASK, 354 SYS_FIELD_PREP_ENUM(SCTLR_EL1, TCF, NONE)); 355 isb(); 356 } 357 358 static bool is_el1_mte_sync_tag_check_fault(unsigned long esr) 359 { 360 unsigned long fsc = esr & ESR_ELx_FSC; 361 362 if (!is_el1_data_abort(esr)) 363 return false; 364 365 if (fsc == ESR_ELx_FSC_MTE) 366 return true; 367 368 return false; 369 } 370 371 static bool is_translation_fault(unsigned long esr) 372 { 373 return (esr & ESR_ELx_FSC_TYPE) == ESR_ELx_FSC_FAULT; 374 } 375 376 static void __do_kernel_fault(unsigned long addr, unsigned long esr, 377 struct pt_regs *regs) 378 { 379 const char *msg; 380 381 /* 382 * Are we prepared to handle this kernel fault? 383 * We are almost certainly not prepared to handle instruction faults. 384 */ 385 if (!is_el1_instruction_abort(esr) && fixup_exception(regs)) 386 return; 387 388 if (WARN_RATELIMIT(is_spurious_el1_translation_fault(addr, esr, regs), 389 "Ignoring spurious kernel translation fault at virtual address %016lx\n", addr)) 390 return; 391 392 if (is_el1_mte_sync_tag_check_fault(esr)) { 393 do_tag_recovery(addr, esr, regs); 394 395 return; 396 } 397 398 if (is_el1_permission_fault(addr, esr, regs)) { 399 if (esr & ESR_ELx_WNR) 400 msg = "write to read-only memory"; 401 else if (is_el1_instruction_abort(esr)) 402 msg = "execute from non-executable memory"; 403 else 404 msg = "read from unreadable memory"; 405 } else if (addr < PAGE_SIZE) { 406 msg = "NULL pointer dereference"; 407 } else { 408 if (is_translation_fault(esr) && 409 kfence_handle_page_fault(addr, esr & ESR_ELx_WNR, regs)) 410 return; 411 412 msg = "paging request"; 413 } 414 415 if (efi_runtime_fixup_exception(regs, msg)) 416 return; 417 418 die_kernel_fault(msg, addr, esr, regs); 419 } 420 421 static void set_thread_esr(unsigned long address, unsigned long esr) 422 { 423 current->thread.fault_address = address; 424 425 /* 426 * If the faulting address is in the kernel, we must sanitize the ESR. 427 * From userspace's point of view, kernel-only mappings don't exist 428 * at all, so we report them as level 0 translation faults. 429 * (This is not quite the way that "no mapping there at all" behaves: 430 * an alignment fault not caused by the memory type would take 431 * precedence over translation fault for a real access to empty 432 * space. Unfortunately we can't easily distinguish "alignment fault 433 * not caused by memory type" from "alignment fault caused by memory 434 * type", so we ignore this wrinkle and just return the translation 435 * fault.) 436 */ 437 if (!is_ttbr0_addr(current->thread.fault_address)) { 438 switch (ESR_ELx_EC(esr)) { 439 case ESR_ELx_EC_DABT_LOW: 440 /* 441 * These bits provide only information about the 442 * faulting instruction, which userspace knows already. 443 * We explicitly clear bits which are architecturally 444 * RES0 in case they are given meanings in future. 445 * We always report the ESR as if the fault was taken 446 * to EL1 and so ISV and the bits in ISS[23:14] are 447 * clear. (In fact it always will be a fault to EL1.) 448 */ 449 esr &= ESR_ELx_EC_MASK | ESR_ELx_IL | 450 ESR_ELx_CM | ESR_ELx_WNR; 451 esr |= ESR_ELx_FSC_FAULT; 452 break; 453 case ESR_ELx_EC_IABT_LOW: 454 /* 455 * Claim a level 0 translation fault. 456 * All other bits are architecturally RES0 for faults 457 * reported with that DFSC value, so we clear them. 458 */ 459 esr &= ESR_ELx_EC_MASK | ESR_ELx_IL; 460 esr |= ESR_ELx_FSC_FAULT; 461 break; 462 default: 463 /* 464 * This should never happen (entry.S only brings us 465 * into this code for insn and data aborts from a lower 466 * exception level). Fail safe by not providing an ESR 467 * context record at all. 468 */ 469 WARN(1, "ESR 0x%lx is not DABT or IABT from EL0\n", esr); 470 esr = 0; 471 break; 472 } 473 } 474 475 current->thread.fault_code = esr; 476 } 477 478 static void do_bad_area(unsigned long far, unsigned long esr, 479 struct pt_regs *regs) 480 { 481 unsigned long addr = untagged_addr(far); 482 483 /* 484 * If we are in kernel mode at this point, we have no context to 485 * handle this fault with. 486 */ 487 if (user_mode(regs)) { 488 const struct fault_info *inf = esr_to_fault_info(esr); 489 490 set_thread_esr(addr, esr); 491 arm64_force_sig_fault(inf->sig, inf->code, far, inf->name); 492 } else { 493 __do_kernel_fault(addr, esr, regs); 494 } 495 } 496 497 #define VM_FAULT_BADMAP ((__force vm_fault_t)0x010000) 498 #define VM_FAULT_BADACCESS ((__force vm_fault_t)0x020000) 499 500 static vm_fault_t __do_page_fault(struct mm_struct *mm, 501 struct vm_area_struct *vma, unsigned long addr, 502 unsigned int mm_flags, unsigned long vm_flags, 503 struct pt_regs *regs) 504 { 505 /* 506 * Ok, we have a good vm_area for this memory access, so we can handle 507 * it. 508 * Check that the permissions on the VMA allow for the fault which 509 * occurred. 510 */ 511 if (!(vma->vm_flags & vm_flags)) 512 return VM_FAULT_BADACCESS; 513 return handle_mm_fault(vma, addr, mm_flags, regs); 514 } 515 516 static bool is_el0_instruction_abort(unsigned long esr) 517 { 518 return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW; 519 } 520 521 /* 522 * Note: not valid for EL1 DC IVAC, but we never use that such that it 523 * should fault. EL0 cannot issue DC IVAC (undef). 524 */ 525 static bool is_write_abort(unsigned long esr) 526 { 527 return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM); 528 } 529 530 static int __kprobes do_page_fault(unsigned long far, unsigned long esr, 531 struct pt_regs *regs) 532 { 533 const struct fault_info *inf; 534 struct mm_struct *mm = current->mm; 535 vm_fault_t fault; 536 unsigned long vm_flags; 537 unsigned int mm_flags = FAULT_FLAG_DEFAULT; 538 unsigned long addr = untagged_addr(far); 539 struct vm_area_struct *vma; 540 541 if (kprobe_page_fault(regs, esr)) 542 return 0; 543 544 /* 545 * If we're in an interrupt or have no user context, we must not take 546 * the fault. 547 */ 548 if (faulthandler_disabled() || !mm) 549 goto no_context; 550 551 if (user_mode(regs)) 552 mm_flags |= FAULT_FLAG_USER; 553 554 /* 555 * vm_flags tells us what bits we must have in vma->vm_flags 556 * for the fault to be benign, __do_page_fault() would check 557 * vma->vm_flags & vm_flags and returns an error if the 558 * intersection is empty 559 */ 560 if (is_el0_instruction_abort(esr)) { 561 /* It was exec fault */ 562 vm_flags = VM_EXEC; 563 mm_flags |= FAULT_FLAG_INSTRUCTION; 564 } else if (is_write_abort(esr)) { 565 /* It was write fault */ 566 vm_flags = VM_WRITE; 567 mm_flags |= FAULT_FLAG_WRITE; 568 } else { 569 /* It was read fault */ 570 vm_flags = VM_READ; 571 /* Write implies read */ 572 vm_flags |= VM_WRITE; 573 /* If EPAN is absent then exec implies read */ 574 if (!cpus_have_const_cap(ARM64_HAS_EPAN)) 575 vm_flags |= VM_EXEC; 576 } 577 578 if (is_ttbr0_addr(addr) && is_el1_permission_fault(addr, esr, regs)) { 579 if (is_el1_instruction_abort(esr)) 580 die_kernel_fault("execution of user memory", 581 addr, esr, regs); 582 583 if (!search_exception_tables(regs->pc)) 584 die_kernel_fault("access to user memory outside uaccess routines", 585 addr, esr, regs); 586 } 587 588 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); 589 590 if (!(mm_flags & FAULT_FLAG_USER)) 591 goto lock_mmap; 592 593 vma = lock_vma_under_rcu(mm, addr); 594 if (!vma) 595 goto lock_mmap; 596 597 if (!(vma->vm_flags & vm_flags)) { 598 vma_end_read(vma); 599 goto lock_mmap; 600 } 601 fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs); 602 if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED))) 603 vma_end_read(vma); 604 605 if (!(fault & VM_FAULT_RETRY)) { 606 count_vm_vma_lock_event(VMA_LOCK_SUCCESS); 607 goto done; 608 } 609 count_vm_vma_lock_event(VMA_LOCK_RETRY); 610 611 /* Quick path to respond to signals */ 612 if (fault_signal_pending(fault, regs)) { 613 if (!user_mode(regs)) 614 goto no_context; 615 return 0; 616 } 617 lock_mmap: 618 619 retry: 620 vma = lock_mm_and_find_vma(mm, addr, regs); 621 if (unlikely(!vma)) { 622 fault = VM_FAULT_BADMAP; 623 goto done; 624 } 625 626 fault = __do_page_fault(mm, vma, addr, mm_flags, vm_flags, regs); 627 628 /* Quick path to respond to signals */ 629 if (fault_signal_pending(fault, regs)) { 630 if (!user_mode(regs)) 631 goto no_context; 632 return 0; 633 } 634 635 /* The fault is fully completed (including releasing mmap lock) */ 636 if (fault & VM_FAULT_COMPLETED) 637 return 0; 638 639 if (fault & VM_FAULT_RETRY) { 640 mm_flags |= FAULT_FLAG_TRIED; 641 goto retry; 642 } 643 mmap_read_unlock(mm); 644 645 done: 646 /* 647 * Handle the "normal" (no error) case first. 648 */ 649 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | 650 VM_FAULT_BADACCESS)))) 651 return 0; 652 653 /* 654 * If we are in kernel mode at this point, we have no context to 655 * handle this fault with. 656 */ 657 if (!user_mode(regs)) 658 goto no_context; 659 660 if (fault & VM_FAULT_OOM) { 661 /* 662 * We ran out of memory, call the OOM killer, and return to 663 * userspace (which will retry the fault, or kill us if we got 664 * oom-killed). 665 */ 666 pagefault_out_of_memory(); 667 return 0; 668 } 669 670 inf = esr_to_fault_info(esr); 671 set_thread_esr(addr, esr); 672 if (fault & VM_FAULT_SIGBUS) { 673 /* 674 * We had some memory, but were unable to successfully fix up 675 * this page fault. 676 */ 677 arm64_force_sig_fault(SIGBUS, BUS_ADRERR, far, inf->name); 678 } else if (fault & (VM_FAULT_HWPOISON_LARGE | VM_FAULT_HWPOISON)) { 679 unsigned int lsb; 680 681 lsb = PAGE_SHIFT; 682 if (fault & VM_FAULT_HWPOISON_LARGE) 683 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); 684 685 arm64_force_sig_mceerr(BUS_MCEERR_AR, far, lsb, inf->name); 686 } else { 687 /* 688 * Something tried to access memory that isn't in our memory 689 * map. 690 */ 691 arm64_force_sig_fault(SIGSEGV, 692 fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR, 693 far, inf->name); 694 } 695 696 return 0; 697 698 no_context: 699 __do_kernel_fault(addr, esr, regs); 700 return 0; 701 } 702 703 static int __kprobes do_translation_fault(unsigned long far, 704 unsigned long esr, 705 struct pt_regs *regs) 706 { 707 unsigned long addr = untagged_addr(far); 708 709 if (is_ttbr0_addr(addr)) 710 return do_page_fault(far, esr, regs); 711 712 do_bad_area(far, esr, regs); 713 return 0; 714 } 715 716 static int do_alignment_fault(unsigned long far, unsigned long esr, 717 struct pt_regs *regs) 718 { 719 if (IS_ENABLED(CONFIG_COMPAT_ALIGNMENT_FIXUPS) && 720 compat_user_mode(regs)) 721 return do_compat_alignment_fixup(far, regs); 722 do_bad_area(far, esr, regs); 723 return 0; 724 } 725 726 static int do_bad(unsigned long far, unsigned long esr, struct pt_regs *regs) 727 { 728 return 1; /* "fault" */ 729 } 730 731 static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs) 732 { 733 const struct fault_info *inf; 734 unsigned long siaddr; 735 736 inf = esr_to_fault_info(esr); 737 738 if (user_mode(regs) && apei_claim_sea(regs) == 0) { 739 /* 740 * APEI claimed this as a firmware-first notification. 741 * Some processing deferred to task_work before ret_to_user(). 742 */ 743 return 0; 744 } 745 746 if (esr & ESR_ELx_FnV) { 747 siaddr = 0; 748 } else { 749 /* 750 * The architecture specifies that the tag bits of FAR_EL1 are 751 * UNKNOWN for synchronous external aborts. Mask them out now 752 * so that userspace doesn't see them. 753 */ 754 siaddr = untagged_addr(far); 755 } 756 arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr); 757 758 return 0; 759 } 760 761 static int do_tag_check_fault(unsigned long far, unsigned long esr, 762 struct pt_regs *regs) 763 { 764 /* 765 * The architecture specifies that bits 63:60 of FAR_EL1 are UNKNOWN 766 * for tag check faults. Set them to corresponding bits in the untagged 767 * address. 768 */ 769 far = (__untagged_addr(far) & ~MTE_TAG_MASK) | (far & MTE_TAG_MASK); 770 do_bad_area(far, esr, regs); 771 return 0; 772 } 773 774 static const struct fault_info fault_info[] = { 775 { do_bad, SIGKILL, SI_KERNEL, "ttbr address size fault" }, 776 { do_bad, SIGKILL, SI_KERNEL, "level 1 address size fault" }, 777 { do_bad, SIGKILL, SI_KERNEL, "level 2 address size fault" }, 778 { do_bad, SIGKILL, SI_KERNEL, "level 3 address size fault" }, 779 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 0 translation fault" }, 780 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" }, 781 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" }, 782 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" }, 783 { do_bad, SIGKILL, SI_KERNEL, "unknown 8" }, 784 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" }, 785 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" }, 786 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 access flag fault" }, 787 { do_bad, SIGKILL, SI_KERNEL, "unknown 12" }, 788 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 permission fault" }, 789 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 permission fault" }, 790 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 permission fault" }, 791 { do_sea, SIGBUS, BUS_OBJERR, "synchronous external abort" }, 792 { do_tag_check_fault, SIGSEGV, SEGV_MTESERR, "synchronous tag check fault" }, 793 { do_bad, SIGKILL, SI_KERNEL, "unknown 18" }, 794 { do_bad, SIGKILL, SI_KERNEL, "unknown 19" }, 795 { do_sea, SIGKILL, SI_KERNEL, "level 0 (translation table walk)" }, 796 { do_sea, SIGKILL, SI_KERNEL, "level 1 (translation table walk)" }, 797 { do_sea, SIGKILL, SI_KERNEL, "level 2 (translation table walk)" }, 798 { do_sea, SIGKILL, SI_KERNEL, "level 3 (translation table walk)" }, 799 { do_sea, SIGBUS, BUS_OBJERR, "synchronous parity or ECC error" }, // Reserved when RAS is implemented 800 { do_bad, SIGKILL, SI_KERNEL, "unknown 25" }, 801 { do_bad, SIGKILL, SI_KERNEL, "unknown 26" }, 802 { do_bad, SIGKILL, SI_KERNEL, "unknown 27" }, 803 { do_sea, SIGKILL, SI_KERNEL, "level 0 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented 804 { do_sea, SIGKILL, SI_KERNEL, "level 1 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented 805 { do_sea, SIGKILL, SI_KERNEL, "level 2 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented 806 { do_sea, SIGKILL, SI_KERNEL, "level 3 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented 807 { do_bad, SIGKILL, SI_KERNEL, "unknown 32" }, 808 { do_alignment_fault, SIGBUS, BUS_ADRALN, "alignment fault" }, 809 { do_bad, SIGKILL, SI_KERNEL, "unknown 34" }, 810 { do_bad, SIGKILL, SI_KERNEL, "unknown 35" }, 811 { do_bad, SIGKILL, SI_KERNEL, "unknown 36" }, 812 { do_bad, SIGKILL, SI_KERNEL, "unknown 37" }, 813 { do_bad, SIGKILL, SI_KERNEL, "unknown 38" }, 814 { do_bad, SIGKILL, SI_KERNEL, "unknown 39" }, 815 { do_bad, SIGKILL, SI_KERNEL, "unknown 40" }, 816 { do_bad, SIGKILL, SI_KERNEL, "unknown 41" }, 817 { do_bad, SIGKILL, SI_KERNEL, "unknown 42" }, 818 { do_bad, SIGKILL, SI_KERNEL, "unknown 43" }, 819 { do_bad, SIGKILL, SI_KERNEL, "unknown 44" }, 820 { do_bad, SIGKILL, SI_KERNEL, "unknown 45" }, 821 { do_bad, SIGKILL, SI_KERNEL, "unknown 46" }, 822 { do_bad, SIGKILL, SI_KERNEL, "unknown 47" }, 823 { do_bad, SIGKILL, SI_KERNEL, "TLB conflict abort" }, 824 { do_bad, SIGKILL, SI_KERNEL, "Unsupported atomic hardware update fault" }, 825 { do_bad, SIGKILL, SI_KERNEL, "unknown 50" }, 826 { do_bad, SIGKILL, SI_KERNEL, "unknown 51" }, 827 { do_bad, SIGKILL, SI_KERNEL, "implementation fault (lockdown abort)" }, 828 { do_bad, SIGBUS, BUS_OBJERR, "implementation fault (unsupported exclusive)" }, 829 { do_bad, SIGKILL, SI_KERNEL, "unknown 54" }, 830 { do_bad, SIGKILL, SI_KERNEL, "unknown 55" }, 831 { do_bad, SIGKILL, SI_KERNEL, "unknown 56" }, 832 { do_bad, SIGKILL, SI_KERNEL, "unknown 57" }, 833 { do_bad, SIGKILL, SI_KERNEL, "unknown 58" }, 834 { do_bad, SIGKILL, SI_KERNEL, "unknown 59" }, 835 { do_bad, SIGKILL, SI_KERNEL, "unknown 60" }, 836 { do_bad, SIGKILL, SI_KERNEL, "section domain fault" }, 837 { do_bad, SIGKILL, SI_KERNEL, "page domain fault" }, 838 { do_bad, SIGKILL, SI_KERNEL, "unknown 63" }, 839 }; 840 841 void do_mem_abort(unsigned long far, unsigned long esr, struct pt_regs *regs) 842 { 843 const struct fault_info *inf = esr_to_fault_info(esr); 844 unsigned long addr = untagged_addr(far); 845 846 if (!inf->fn(far, esr, regs)) 847 return; 848 849 if (!user_mode(regs)) 850 die_kernel_fault(inf->name, addr, esr, regs); 851 852 /* 853 * At this point we have an unrecognized fault type whose tag bits may 854 * have been defined as UNKNOWN. Therefore we only expose the untagged 855 * address to the signal handler. 856 */ 857 arm64_notify_die(inf->name, regs, inf->sig, inf->code, addr, esr); 858 } 859 NOKPROBE_SYMBOL(do_mem_abort); 860 861 void do_sp_pc_abort(unsigned long addr, unsigned long esr, struct pt_regs *regs) 862 { 863 arm64_notify_die("SP/PC alignment exception", regs, SIGBUS, BUS_ADRALN, 864 addr, esr); 865 } 866 NOKPROBE_SYMBOL(do_sp_pc_abort); 867 868 /* 869 * __refdata because early_brk64 is __init, but the reference to it is 870 * clobbered at arch_initcall time. 871 * See traps.c and debug-monitors.c:debug_traps_init(). 872 */ 873 static struct fault_info __refdata debug_fault_info[] = { 874 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" }, 875 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" }, 876 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" }, 877 { do_bad, SIGKILL, SI_KERNEL, "unknown 3" }, 878 { do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" }, 879 { do_bad, SIGKILL, SI_KERNEL, "aarch32 vector catch" }, 880 { early_brk64, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" }, 881 { do_bad, SIGKILL, SI_KERNEL, "unknown 7" }, 882 }; 883 884 void __init hook_debug_fault_code(int nr, 885 int (*fn)(unsigned long, unsigned long, struct pt_regs *), 886 int sig, int code, const char *name) 887 { 888 BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info)); 889 890 debug_fault_info[nr].fn = fn; 891 debug_fault_info[nr].sig = sig; 892 debug_fault_info[nr].code = code; 893 debug_fault_info[nr].name = name; 894 } 895 896 /* 897 * In debug exception context, we explicitly disable preemption despite 898 * having interrupts disabled. 899 * This serves two purposes: it makes it much less likely that we would 900 * accidentally schedule in exception context and it will force a warning 901 * if we somehow manage to schedule by accident. 902 */ 903 static void debug_exception_enter(struct pt_regs *regs) 904 { 905 preempt_disable(); 906 907 /* This code is a bit fragile. Test it. */ 908 RCU_LOCKDEP_WARN(!rcu_is_watching(), "exception_enter didn't work"); 909 } 910 NOKPROBE_SYMBOL(debug_exception_enter); 911 912 static void debug_exception_exit(struct pt_regs *regs) 913 { 914 preempt_enable_no_resched(); 915 } 916 NOKPROBE_SYMBOL(debug_exception_exit); 917 918 void do_debug_exception(unsigned long addr_if_watchpoint, unsigned long esr, 919 struct pt_regs *regs) 920 { 921 const struct fault_info *inf = esr_to_debug_fault_info(esr); 922 unsigned long pc = instruction_pointer(regs); 923 924 debug_exception_enter(regs); 925 926 if (user_mode(regs) && !is_ttbr0_addr(pc)) 927 arm64_apply_bp_hardening(); 928 929 if (inf->fn(addr_if_watchpoint, esr, regs)) { 930 arm64_notify_die(inf->name, regs, inf->sig, inf->code, pc, esr); 931 } 932 933 debug_exception_exit(regs); 934 } 935 NOKPROBE_SYMBOL(do_debug_exception); 936 937 /* 938 * Used during anonymous page fault handling. 939 */ 940 struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, 941 unsigned long vaddr) 942 { 943 gfp_t flags = GFP_HIGHUSER_MOVABLE | __GFP_ZERO; 944 945 /* 946 * If the page is mapped with PROT_MTE, initialise the tags at the 947 * point of allocation and page zeroing as this is usually faster than 948 * separate DC ZVA and STGM. 949 */ 950 if (vma->vm_flags & VM_MTE) 951 flags |= __GFP_ZEROTAGS; 952 953 return vma_alloc_folio(flags, 0, vma, vaddr, false); 954 } 955 956 void tag_clear_highpage(struct page *page) 957 { 958 /* Newly allocated page, shouldn't have been tagged yet */ 959 WARN_ON_ONCE(!try_page_mte_tagging(page)); 960 mte_zero_clear_page_tags(page_address(page)); 961 set_page_mte_tagged(page); 962 }