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 pte = READ_ONCE(*ptep); 192 pr_cont(", pte=%016llx", pte_val(pte)); 193 pte_unmap(ptep); 194 } while(0); 195 196 pr_cont("\n"); 197 } 198 199 /* 200 * This function sets the access flags (dirty, accessed), as well as write 201 * permission, and only to a more permissive setting. 202 * 203 * It needs to cope with hardware update of the accessed/dirty state by other 204 * agents in the system and can safely skip the __sync_icache_dcache() call as, 205 * like set_pte_at(), the PTE is never changed from no-exec to exec here. 206 * 207 * Returns whether or not the PTE actually changed. 208 */ 209 int ptep_set_access_flags(struct vm_area_struct *vma, 210 unsigned long address, pte_t *ptep, 211 pte_t entry, int dirty) 212 { 213 pteval_t old_pteval, pteval; 214 pte_t pte = READ_ONCE(*ptep); 215 216 if (pte_same(pte, entry)) 217 return 0; 218 219 /* only preserve the access flags and write permission */ 220 pte_val(entry) &= PTE_RDONLY | PTE_AF | PTE_WRITE | PTE_DIRTY; 221 222 /* 223 * Setting the flags must be done atomically to avoid racing with the 224 * hardware update of the access/dirty state. The PTE_RDONLY bit must 225 * be set to the most permissive (lowest value) of *ptep and entry 226 * (calculated as: a & b == ~(~a | ~b)). 227 */ 228 pte_val(entry) ^= PTE_RDONLY; 229 pteval = pte_val(pte); 230 do { 231 old_pteval = pteval; 232 pteval ^= PTE_RDONLY; 233 pteval |= pte_val(entry); 234 pteval ^= PTE_RDONLY; 235 pteval = cmpxchg_relaxed(&pte_val(*ptep), old_pteval, pteval); 236 } while (pteval != old_pteval); 237 238 /* Invalidate a stale read-only entry */ 239 if (dirty) 240 flush_tlb_page(vma, address); 241 return 1; 242 } 243 244 static bool is_el1_instruction_abort(unsigned long esr) 245 { 246 return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR; 247 } 248 249 static bool is_el1_data_abort(unsigned long esr) 250 { 251 return ESR_ELx_EC(esr) == ESR_ELx_EC_DABT_CUR; 252 } 253 254 static inline bool is_el1_permission_fault(unsigned long addr, unsigned long esr, 255 struct pt_regs *regs) 256 { 257 unsigned long fsc_type = esr & ESR_ELx_FSC_TYPE; 258 259 if (!is_el1_data_abort(esr) && !is_el1_instruction_abort(esr)) 260 return false; 261 262 if (fsc_type == ESR_ELx_FSC_PERM) 263 return true; 264 265 if (is_ttbr0_addr(addr) && system_uses_ttbr0_pan()) 266 return fsc_type == ESR_ELx_FSC_FAULT && 267 (regs->pstate & PSR_PAN_BIT); 268 269 return false; 270 } 271 272 static bool __kprobes is_spurious_el1_translation_fault(unsigned long addr, 273 unsigned long esr, 274 struct pt_regs *regs) 275 { 276 unsigned long flags; 277 u64 par, dfsc; 278 279 if (!is_el1_data_abort(esr) || 280 (esr & ESR_ELx_FSC_TYPE) != ESR_ELx_FSC_FAULT) 281 return false; 282 283 local_irq_save(flags); 284 asm volatile("at s1e1r, %0" :: "r" (addr)); 285 isb(); 286 par = read_sysreg_par(); 287 local_irq_restore(flags); 288 289 /* 290 * If we now have a valid translation, treat the translation fault as 291 * spurious. 292 */ 293 if (!(par & SYS_PAR_EL1_F)) 294 return true; 295 296 /* 297 * If we got a different type of fault from the AT instruction, 298 * treat the translation fault as spurious. 299 */ 300 dfsc = FIELD_GET(SYS_PAR_EL1_FST, par); 301 return (dfsc & ESR_ELx_FSC_TYPE) != ESR_ELx_FSC_FAULT; 302 } 303 304 static void die_kernel_fault(const char *msg, unsigned long addr, 305 unsigned long esr, struct pt_regs *regs) 306 { 307 bust_spinlocks(1); 308 309 pr_alert("Unable to handle kernel %s at virtual address %016lx\n", msg, 310 addr); 311 312 kasan_non_canonical_hook(addr); 313 314 mem_abort_decode(esr); 315 316 show_pte(addr); 317 die("Oops", regs, esr); 318 bust_spinlocks(0); 319 make_task_dead(SIGKILL); 320 } 321 322 #ifdef CONFIG_KASAN_HW_TAGS 323 static void report_tag_fault(unsigned long addr, unsigned long esr, 324 struct pt_regs *regs) 325 { 326 /* 327 * SAS bits aren't set for all faults reported in EL1, so we can't 328 * find out access size. 329 */ 330 bool is_write = !!(esr & ESR_ELx_WNR); 331 kasan_report(addr, 0, is_write, regs->pc); 332 } 333 #else 334 /* Tag faults aren't enabled without CONFIG_KASAN_HW_TAGS. */ 335 static inline void report_tag_fault(unsigned long addr, unsigned long esr, 336 struct pt_regs *regs) { } 337 #endif 338 339 static void do_tag_recovery(unsigned long addr, unsigned long esr, 340 struct pt_regs *regs) 341 { 342 343 report_tag_fault(addr, esr, regs); 344 345 /* 346 * Disable MTE Tag Checking on the local CPU for the current EL. 347 * It will be done lazily on the other CPUs when they will hit a 348 * tag fault. 349 */ 350 sysreg_clear_set(sctlr_el1, SCTLR_EL1_TCF_MASK, 351 SYS_FIELD_PREP_ENUM(SCTLR_EL1, TCF, NONE)); 352 isb(); 353 } 354 355 static bool is_el1_mte_sync_tag_check_fault(unsigned long esr) 356 { 357 unsigned long fsc = esr & ESR_ELx_FSC; 358 359 if (!is_el1_data_abort(esr)) 360 return false; 361 362 if (fsc == ESR_ELx_FSC_MTE) 363 return true; 364 365 return false; 366 } 367 368 static bool is_translation_fault(unsigned long esr) 369 { 370 return (esr & ESR_ELx_FSC_TYPE) == ESR_ELx_FSC_FAULT; 371 } 372 373 static void __do_kernel_fault(unsigned long addr, unsigned long esr, 374 struct pt_regs *regs) 375 { 376 const char *msg; 377 378 /* 379 * Are we prepared to handle this kernel fault? 380 * We are almost certainly not prepared to handle instruction faults. 381 */ 382 if (!is_el1_instruction_abort(esr) && fixup_exception(regs)) 383 return; 384 385 if (WARN_RATELIMIT(is_spurious_el1_translation_fault(addr, esr, regs), 386 "Ignoring spurious kernel translation fault at virtual address %016lx\n", addr)) 387 return; 388 389 if (is_el1_mte_sync_tag_check_fault(esr)) { 390 do_tag_recovery(addr, esr, regs); 391 392 return; 393 } 394 395 if (is_el1_permission_fault(addr, esr, regs)) { 396 if (esr & ESR_ELx_WNR) 397 msg = "write to read-only memory"; 398 else if (is_el1_instruction_abort(esr)) 399 msg = "execute from non-executable memory"; 400 else 401 msg = "read from unreadable memory"; 402 } else if (addr < PAGE_SIZE) { 403 msg = "NULL pointer dereference"; 404 } else { 405 if (is_translation_fault(esr) && 406 kfence_handle_page_fault(addr, esr & ESR_ELx_WNR, regs)) 407 return; 408 409 msg = "paging request"; 410 } 411 412 if (efi_runtime_fixup_exception(regs, msg)) 413 return; 414 415 die_kernel_fault(msg, addr, esr, regs); 416 } 417 418 static void set_thread_esr(unsigned long address, unsigned long esr) 419 { 420 current->thread.fault_address = address; 421 422 /* 423 * If the faulting address is in the kernel, we must sanitize the ESR. 424 * From userspace's point of view, kernel-only mappings don't exist 425 * at all, so we report them as level 0 translation faults. 426 * (This is not quite the way that "no mapping there at all" behaves: 427 * an alignment fault not caused by the memory type would take 428 * precedence over translation fault for a real access to empty 429 * space. Unfortunately we can't easily distinguish "alignment fault 430 * not caused by memory type" from "alignment fault caused by memory 431 * type", so we ignore this wrinkle and just return the translation 432 * fault.) 433 */ 434 if (!is_ttbr0_addr(current->thread.fault_address)) { 435 switch (ESR_ELx_EC(esr)) { 436 case ESR_ELx_EC_DABT_LOW: 437 /* 438 * These bits provide only information about the 439 * faulting instruction, which userspace knows already. 440 * We explicitly clear bits which are architecturally 441 * RES0 in case they are given meanings in future. 442 * We always report the ESR as if the fault was taken 443 * to EL1 and so ISV and the bits in ISS[23:14] are 444 * clear. (In fact it always will be a fault to EL1.) 445 */ 446 esr &= ESR_ELx_EC_MASK | ESR_ELx_IL | 447 ESR_ELx_CM | ESR_ELx_WNR; 448 esr |= ESR_ELx_FSC_FAULT; 449 break; 450 case ESR_ELx_EC_IABT_LOW: 451 /* 452 * Claim a level 0 translation fault. 453 * All other bits are architecturally RES0 for faults 454 * reported with that DFSC value, so we clear them. 455 */ 456 esr &= ESR_ELx_EC_MASK | ESR_ELx_IL; 457 esr |= ESR_ELx_FSC_FAULT; 458 break; 459 default: 460 /* 461 * This should never happen (entry.S only brings us 462 * into this code for insn and data aborts from a lower 463 * exception level). Fail safe by not providing an ESR 464 * context record at all. 465 */ 466 WARN(1, "ESR 0x%lx is not DABT or IABT from EL0\n", esr); 467 esr = 0; 468 break; 469 } 470 } 471 472 current->thread.fault_code = esr; 473 } 474 475 static void do_bad_area(unsigned long far, unsigned long esr, 476 struct pt_regs *regs) 477 { 478 unsigned long addr = untagged_addr(far); 479 480 /* 481 * If we are in kernel mode at this point, we have no context to 482 * handle this fault with. 483 */ 484 if (user_mode(regs)) { 485 const struct fault_info *inf = esr_to_fault_info(esr); 486 487 set_thread_esr(addr, esr); 488 arm64_force_sig_fault(inf->sig, inf->code, far, inf->name); 489 } else { 490 __do_kernel_fault(addr, esr, regs); 491 } 492 } 493 494 #define VM_FAULT_BADMAP ((__force vm_fault_t)0x010000) 495 #define VM_FAULT_BADACCESS ((__force vm_fault_t)0x020000) 496 497 static vm_fault_t __do_page_fault(struct mm_struct *mm, unsigned long addr, 498 unsigned int mm_flags, unsigned long vm_flags, 499 struct pt_regs *regs) 500 { 501 struct vm_area_struct *vma = find_vma(mm, addr); 502 503 if (unlikely(!vma)) 504 return VM_FAULT_BADMAP; 505 506 /* 507 * Ok, we have a good vm_area for this memory access, so we can handle 508 * it. 509 */ 510 if (unlikely(vma->vm_start > addr)) { 511 if (!(vma->vm_flags & VM_GROWSDOWN)) 512 return VM_FAULT_BADMAP; 513 if (expand_stack(vma, addr)) 514 return VM_FAULT_BADMAP; 515 } 516 517 /* 518 * Check that the permissions on the VMA allow for the fault which 519 * occurred. 520 */ 521 if (!(vma->vm_flags & vm_flags)) 522 return VM_FAULT_BADACCESS; 523 return handle_mm_fault(vma, addr, mm_flags, regs); 524 } 525 526 static bool is_el0_instruction_abort(unsigned long esr) 527 { 528 return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW; 529 } 530 531 /* 532 * Note: not valid for EL1 DC IVAC, but we never use that such that it 533 * should fault. EL0 cannot issue DC IVAC (undef). 534 */ 535 static bool is_write_abort(unsigned long esr) 536 { 537 return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM); 538 } 539 540 static int __kprobes do_page_fault(unsigned long far, unsigned long esr, 541 struct pt_regs *regs) 542 { 543 const struct fault_info *inf; 544 struct mm_struct *mm = current->mm; 545 vm_fault_t fault; 546 unsigned long vm_flags; 547 unsigned int mm_flags = FAULT_FLAG_DEFAULT; 548 unsigned long addr = untagged_addr(far); 549 #ifdef CONFIG_PER_VMA_LOCK 550 struct vm_area_struct *vma; 551 #endif 552 553 if (kprobe_page_fault(regs, esr)) 554 return 0; 555 556 /* 557 * If we're in an interrupt or have no user context, we must not take 558 * the fault. 559 */ 560 if (faulthandler_disabled() || !mm) 561 goto no_context; 562 563 if (user_mode(regs)) 564 mm_flags |= FAULT_FLAG_USER; 565 566 /* 567 * vm_flags tells us what bits we must have in vma->vm_flags 568 * for the fault to be benign, __do_page_fault() would check 569 * vma->vm_flags & vm_flags and returns an error if the 570 * intersection is empty 571 */ 572 if (is_el0_instruction_abort(esr)) { 573 /* It was exec fault */ 574 vm_flags = VM_EXEC; 575 mm_flags |= FAULT_FLAG_INSTRUCTION; 576 } else if (is_write_abort(esr)) { 577 /* It was write fault */ 578 vm_flags = VM_WRITE; 579 mm_flags |= FAULT_FLAG_WRITE; 580 } else { 581 /* It was read fault */ 582 vm_flags = VM_READ; 583 /* Write implies read */ 584 vm_flags |= VM_WRITE; 585 /* If EPAN is absent then exec implies read */ 586 if (!cpus_have_const_cap(ARM64_HAS_EPAN)) 587 vm_flags |= VM_EXEC; 588 } 589 590 if (is_ttbr0_addr(addr) && is_el1_permission_fault(addr, esr, regs)) { 591 if (is_el1_instruction_abort(esr)) 592 die_kernel_fault("execution of user memory", 593 addr, esr, regs); 594 595 if (!search_exception_tables(regs->pc)) 596 die_kernel_fault("access to user memory outside uaccess routines", 597 addr, esr, regs); 598 } 599 600 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); 601 602 #ifdef CONFIG_PER_VMA_LOCK 603 if (!(mm_flags & FAULT_FLAG_USER)) 604 goto lock_mmap; 605 606 vma = lock_vma_under_rcu(mm, addr); 607 if (!vma) 608 goto lock_mmap; 609 610 if (!(vma->vm_flags & vm_flags)) { 611 vma_end_read(vma); 612 goto lock_mmap; 613 } 614 fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs); 615 vma_end_read(vma); 616 617 if (!(fault & VM_FAULT_RETRY)) { 618 count_vm_vma_lock_event(VMA_LOCK_SUCCESS); 619 goto done; 620 } 621 count_vm_vma_lock_event(VMA_LOCK_RETRY); 622 623 /* Quick path to respond to signals */ 624 if (fault_signal_pending(fault, regs)) { 625 if (!user_mode(regs)) 626 goto no_context; 627 return 0; 628 } 629 lock_mmap: 630 #endif /* CONFIG_PER_VMA_LOCK */ 631 /* 632 * As per x86, we may deadlock here. However, since the kernel only 633 * validly references user space from well defined areas of the code, 634 * we can bug out early if this is from code which shouldn't. 635 */ 636 if (!mmap_read_trylock(mm)) { 637 if (!user_mode(regs) && !search_exception_tables(regs->pc)) 638 goto no_context; 639 retry: 640 mmap_read_lock(mm); 641 } else { 642 /* 643 * The above mmap_read_trylock() might have succeeded in which 644 * case, we'll have missed the might_sleep() from down_read(). 645 */ 646 might_sleep(); 647 #ifdef CONFIG_DEBUG_VM 648 if (!user_mode(regs) && !search_exception_tables(regs->pc)) { 649 mmap_read_unlock(mm); 650 goto no_context; 651 } 652 #endif 653 } 654 655 fault = __do_page_fault(mm, addr, mm_flags, vm_flags, regs); 656 657 /* Quick path to respond to signals */ 658 if (fault_signal_pending(fault, regs)) { 659 if (!user_mode(regs)) 660 goto no_context; 661 return 0; 662 } 663 664 /* The fault is fully completed (including releasing mmap lock) */ 665 if (fault & VM_FAULT_COMPLETED) 666 return 0; 667 668 if (fault & VM_FAULT_RETRY) { 669 mm_flags |= FAULT_FLAG_TRIED; 670 goto retry; 671 } 672 mmap_read_unlock(mm); 673 674 #ifdef CONFIG_PER_VMA_LOCK 675 done: 676 #endif 677 /* 678 * Handle the "normal" (no error) case first. 679 */ 680 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | 681 VM_FAULT_BADACCESS)))) 682 return 0; 683 684 /* 685 * If we are in kernel mode at this point, we have no context to 686 * handle this fault with. 687 */ 688 if (!user_mode(regs)) 689 goto no_context; 690 691 if (fault & VM_FAULT_OOM) { 692 /* 693 * We ran out of memory, call the OOM killer, and return to 694 * userspace (which will retry the fault, or kill us if we got 695 * oom-killed). 696 */ 697 pagefault_out_of_memory(); 698 return 0; 699 } 700 701 inf = esr_to_fault_info(esr); 702 set_thread_esr(addr, esr); 703 if (fault & VM_FAULT_SIGBUS) { 704 /* 705 * We had some memory, but were unable to successfully fix up 706 * this page fault. 707 */ 708 arm64_force_sig_fault(SIGBUS, BUS_ADRERR, far, inf->name); 709 } else if (fault & (VM_FAULT_HWPOISON_LARGE | VM_FAULT_HWPOISON)) { 710 unsigned int lsb; 711 712 lsb = PAGE_SHIFT; 713 if (fault & VM_FAULT_HWPOISON_LARGE) 714 lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); 715 716 arm64_force_sig_mceerr(BUS_MCEERR_AR, far, lsb, inf->name); 717 } else { 718 /* 719 * Something tried to access memory that isn't in our memory 720 * map. 721 */ 722 arm64_force_sig_fault(SIGSEGV, 723 fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR, 724 far, inf->name); 725 } 726 727 return 0; 728 729 no_context: 730 __do_kernel_fault(addr, esr, regs); 731 return 0; 732 } 733 734 static int __kprobes do_translation_fault(unsigned long far, 735 unsigned long esr, 736 struct pt_regs *regs) 737 { 738 unsigned long addr = untagged_addr(far); 739 740 if (is_ttbr0_addr(addr)) 741 return do_page_fault(far, esr, regs); 742 743 do_bad_area(far, esr, regs); 744 return 0; 745 } 746 747 static int do_alignment_fault(unsigned long far, unsigned long esr, 748 struct pt_regs *regs) 749 { 750 if (IS_ENABLED(CONFIG_COMPAT_ALIGNMENT_FIXUPS) && 751 compat_user_mode(regs)) 752 return do_compat_alignment_fixup(far, regs); 753 do_bad_area(far, esr, regs); 754 return 0; 755 } 756 757 static int do_bad(unsigned long far, unsigned long esr, struct pt_regs *regs) 758 { 759 return 1; /* "fault" */ 760 } 761 762 static int do_sea(unsigned long far, unsigned long esr, struct pt_regs *regs) 763 { 764 const struct fault_info *inf; 765 unsigned long siaddr; 766 767 inf = esr_to_fault_info(esr); 768 769 if (user_mode(regs) && apei_claim_sea(regs) == 0) { 770 /* 771 * APEI claimed this as a firmware-first notification. 772 * Some processing deferred to task_work before ret_to_user(). 773 */ 774 return 0; 775 } 776 777 if (esr & ESR_ELx_FnV) { 778 siaddr = 0; 779 } else { 780 /* 781 * The architecture specifies that the tag bits of FAR_EL1 are 782 * UNKNOWN for synchronous external aborts. Mask them out now 783 * so that userspace doesn't see them. 784 */ 785 siaddr = untagged_addr(far); 786 } 787 arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr); 788 789 return 0; 790 } 791 792 static int do_tag_check_fault(unsigned long far, unsigned long esr, 793 struct pt_regs *regs) 794 { 795 /* 796 * The architecture specifies that bits 63:60 of FAR_EL1 are UNKNOWN 797 * for tag check faults. Set them to corresponding bits in the untagged 798 * address. 799 */ 800 far = (__untagged_addr(far) & ~MTE_TAG_MASK) | (far & MTE_TAG_MASK); 801 do_bad_area(far, esr, regs); 802 return 0; 803 } 804 805 static const struct fault_info fault_info[] = { 806 { do_bad, SIGKILL, SI_KERNEL, "ttbr address size fault" }, 807 { do_bad, SIGKILL, SI_KERNEL, "level 1 address size fault" }, 808 { do_bad, SIGKILL, SI_KERNEL, "level 2 address size fault" }, 809 { do_bad, SIGKILL, SI_KERNEL, "level 3 address size fault" }, 810 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 0 translation fault" }, 811 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" }, 812 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" }, 813 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" }, 814 { do_bad, SIGKILL, SI_KERNEL, "unknown 8" }, 815 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" }, 816 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" }, 817 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 access flag fault" }, 818 { do_bad, SIGKILL, SI_KERNEL, "unknown 12" }, 819 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 permission fault" }, 820 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 permission fault" }, 821 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 permission fault" }, 822 { do_sea, SIGBUS, BUS_OBJERR, "synchronous external abort" }, 823 { do_tag_check_fault, SIGSEGV, SEGV_MTESERR, "synchronous tag check fault" }, 824 { do_bad, SIGKILL, SI_KERNEL, "unknown 18" }, 825 { do_bad, SIGKILL, SI_KERNEL, "unknown 19" }, 826 { do_sea, SIGKILL, SI_KERNEL, "level 0 (translation table walk)" }, 827 { do_sea, SIGKILL, SI_KERNEL, "level 1 (translation table walk)" }, 828 { do_sea, SIGKILL, SI_KERNEL, "level 2 (translation table walk)" }, 829 { do_sea, SIGKILL, SI_KERNEL, "level 3 (translation table walk)" }, 830 { do_sea, SIGBUS, BUS_OBJERR, "synchronous parity or ECC error" }, // Reserved when RAS is implemented 831 { do_bad, SIGKILL, SI_KERNEL, "unknown 25" }, 832 { do_bad, SIGKILL, SI_KERNEL, "unknown 26" }, 833 { do_bad, SIGKILL, SI_KERNEL, "unknown 27" }, 834 { do_sea, SIGKILL, SI_KERNEL, "level 0 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented 835 { do_sea, SIGKILL, SI_KERNEL, "level 1 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented 836 { do_sea, SIGKILL, SI_KERNEL, "level 2 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented 837 { do_sea, SIGKILL, SI_KERNEL, "level 3 synchronous parity error (translation table walk)" }, // Reserved when RAS is implemented 838 { do_bad, SIGKILL, SI_KERNEL, "unknown 32" }, 839 { do_alignment_fault, SIGBUS, BUS_ADRALN, "alignment fault" }, 840 { do_bad, SIGKILL, SI_KERNEL, "unknown 34" }, 841 { do_bad, SIGKILL, SI_KERNEL, "unknown 35" }, 842 { do_bad, SIGKILL, SI_KERNEL, "unknown 36" }, 843 { do_bad, SIGKILL, SI_KERNEL, "unknown 37" }, 844 { do_bad, SIGKILL, SI_KERNEL, "unknown 38" }, 845 { do_bad, SIGKILL, SI_KERNEL, "unknown 39" }, 846 { do_bad, SIGKILL, SI_KERNEL, "unknown 40" }, 847 { do_bad, SIGKILL, SI_KERNEL, "unknown 41" }, 848 { do_bad, SIGKILL, SI_KERNEL, "unknown 42" }, 849 { do_bad, SIGKILL, SI_KERNEL, "unknown 43" }, 850 { do_bad, SIGKILL, SI_KERNEL, "unknown 44" }, 851 { do_bad, SIGKILL, SI_KERNEL, "unknown 45" }, 852 { do_bad, SIGKILL, SI_KERNEL, "unknown 46" }, 853 { do_bad, SIGKILL, SI_KERNEL, "unknown 47" }, 854 { do_bad, SIGKILL, SI_KERNEL, "TLB conflict abort" }, 855 { do_bad, SIGKILL, SI_KERNEL, "Unsupported atomic hardware update fault" }, 856 { do_bad, SIGKILL, SI_KERNEL, "unknown 50" }, 857 { do_bad, SIGKILL, SI_KERNEL, "unknown 51" }, 858 { do_bad, SIGKILL, SI_KERNEL, "implementation fault (lockdown abort)" }, 859 { do_bad, SIGBUS, BUS_OBJERR, "implementation fault (unsupported exclusive)" }, 860 { do_bad, SIGKILL, SI_KERNEL, "unknown 54" }, 861 { do_bad, SIGKILL, SI_KERNEL, "unknown 55" }, 862 { do_bad, SIGKILL, SI_KERNEL, "unknown 56" }, 863 { do_bad, SIGKILL, SI_KERNEL, "unknown 57" }, 864 { do_bad, SIGKILL, SI_KERNEL, "unknown 58" }, 865 { do_bad, SIGKILL, SI_KERNEL, "unknown 59" }, 866 { do_bad, SIGKILL, SI_KERNEL, "unknown 60" }, 867 { do_bad, SIGKILL, SI_KERNEL, "section domain fault" }, 868 { do_bad, SIGKILL, SI_KERNEL, "page domain fault" }, 869 { do_bad, SIGKILL, SI_KERNEL, "unknown 63" }, 870 }; 871 872 void do_mem_abort(unsigned long far, unsigned long esr, struct pt_regs *regs) 873 { 874 const struct fault_info *inf = esr_to_fault_info(esr); 875 unsigned long addr = untagged_addr(far); 876 877 if (!inf->fn(far, esr, regs)) 878 return; 879 880 if (!user_mode(regs)) 881 die_kernel_fault(inf->name, addr, esr, regs); 882 883 /* 884 * At this point we have an unrecognized fault type whose tag bits may 885 * have been defined as UNKNOWN. Therefore we only expose the untagged 886 * address to the signal handler. 887 */ 888 arm64_notify_die(inf->name, regs, inf->sig, inf->code, addr, esr); 889 } 890 NOKPROBE_SYMBOL(do_mem_abort); 891 892 void do_sp_pc_abort(unsigned long addr, unsigned long esr, struct pt_regs *regs) 893 { 894 arm64_notify_die("SP/PC alignment exception", regs, SIGBUS, BUS_ADRALN, 895 addr, esr); 896 } 897 NOKPROBE_SYMBOL(do_sp_pc_abort); 898 899 /* 900 * __refdata because early_brk64 is __init, but the reference to it is 901 * clobbered at arch_initcall time. 902 * See traps.c and debug-monitors.c:debug_traps_init(). 903 */ 904 static struct fault_info __refdata debug_fault_info[] = { 905 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" }, 906 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" }, 907 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" }, 908 { do_bad, SIGKILL, SI_KERNEL, "unknown 3" }, 909 { do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" }, 910 { do_bad, SIGKILL, SI_KERNEL, "aarch32 vector catch" }, 911 { early_brk64, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" }, 912 { do_bad, SIGKILL, SI_KERNEL, "unknown 7" }, 913 }; 914 915 void __init hook_debug_fault_code(int nr, 916 int (*fn)(unsigned long, unsigned long, struct pt_regs *), 917 int sig, int code, const char *name) 918 { 919 BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info)); 920 921 debug_fault_info[nr].fn = fn; 922 debug_fault_info[nr].sig = sig; 923 debug_fault_info[nr].code = code; 924 debug_fault_info[nr].name = name; 925 } 926 927 /* 928 * In debug exception context, we explicitly disable preemption despite 929 * having interrupts disabled. 930 * This serves two purposes: it makes it much less likely that we would 931 * accidentally schedule in exception context and it will force a warning 932 * if we somehow manage to schedule by accident. 933 */ 934 static void debug_exception_enter(struct pt_regs *regs) 935 { 936 preempt_disable(); 937 938 /* This code is a bit fragile. Test it. */ 939 RCU_LOCKDEP_WARN(!rcu_is_watching(), "exception_enter didn't work"); 940 } 941 NOKPROBE_SYMBOL(debug_exception_enter); 942 943 static void debug_exception_exit(struct pt_regs *regs) 944 { 945 preempt_enable_no_resched(); 946 } 947 NOKPROBE_SYMBOL(debug_exception_exit); 948 949 void do_debug_exception(unsigned long addr_if_watchpoint, unsigned long esr, 950 struct pt_regs *regs) 951 { 952 const struct fault_info *inf = esr_to_debug_fault_info(esr); 953 unsigned long pc = instruction_pointer(regs); 954 955 debug_exception_enter(regs); 956 957 if (user_mode(regs) && !is_ttbr0_addr(pc)) 958 arm64_apply_bp_hardening(); 959 960 if (inf->fn(addr_if_watchpoint, esr, regs)) { 961 arm64_notify_die(inf->name, regs, inf->sig, inf->code, pc, esr); 962 } 963 964 debug_exception_exit(regs); 965 } 966 NOKPROBE_SYMBOL(do_debug_exception); 967 968 /* 969 * Used during anonymous page fault handling. 970 */ 971 struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, 972 unsigned long vaddr) 973 { 974 gfp_t flags = GFP_HIGHUSER_MOVABLE | __GFP_ZERO; 975 976 /* 977 * If the page is mapped with PROT_MTE, initialise the tags at the 978 * point of allocation and page zeroing as this is usually faster than 979 * separate DC ZVA and STGM. 980 */ 981 if (vma->vm_flags & VM_MTE) 982 flags |= __GFP_ZEROTAGS; 983 984 return vma_alloc_folio(flags, 0, vma, vaddr, false); 985 } 986 987 void tag_clear_highpage(struct page *page) 988 { 989 /* Newly allocated page, shouldn't have been tagged yet */ 990 WARN_ON_ONCE(!try_page_mte_tagging(page)); 991 mte_zero_clear_page_tags(page_address(page)); 992 set_page_mte_tagged(page); 993 } 994