1 /* 2 * Based on arch/arm/mm/fault.c 3 * 4 * Copyright (C) 1995 Linus Torvalds 5 * Copyright (C) 1995-2004 Russell King 6 * Copyright (C) 2012 ARM Ltd. 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program. If not, see <http://www.gnu.org/licenses/>. 19 */ 20 21 #include <linux/extable.h> 22 #include <linux/signal.h> 23 #include <linux/mm.h> 24 #include <linux/hardirq.h> 25 #include <linux/init.h> 26 #include <linux/kprobes.h> 27 #include <linux/uaccess.h> 28 #include <linux/page-flags.h> 29 #include <linux/sched.h> 30 #include <linux/highmem.h> 31 #include <linux/perf_event.h> 32 #include <linux/preempt.h> 33 34 #include <asm/bug.h> 35 #include <asm/cpufeature.h> 36 #include <asm/exception.h> 37 #include <asm/debug-monitors.h> 38 #include <asm/esr.h> 39 #include <asm/sysreg.h> 40 #include <asm/system_misc.h> 41 #include <asm/pgtable.h> 42 #include <asm/tlbflush.h> 43 44 static const char *fault_name(unsigned int esr); 45 46 #ifdef CONFIG_KPROBES 47 static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) 48 { 49 int ret = 0; 50 51 /* kprobe_running() needs smp_processor_id() */ 52 if (!user_mode(regs)) { 53 preempt_disable(); 54 if (kprobe_running() && kprobe_fault_handler(regs, esr)) 55 ret = 1; 56 preempt_enable(); 57 } 58 59 return ret; 60 } 61 #else 62 static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) 63 { 64 return 0; 65 } 66 #endif 67 68 /* 69 * Dump out the page tables associated with 'addr' in mm 'mm'. 70 */ 71 void show_pte(struct mm_struct *mm, unsigned long addr) 72 { 73 pgd_t *pgd; 74 75 if (!mm) 76 mm = &init_mm; 77 78 pr_alert("pgd = %p\n", mm->pgd); 79 pgd = pgd_offset(mm, addr); 80 pr_alert("[%08lx] *pgd=%016llx", addr, pgd_val(*pgd)); 81 82 do { 83 pud_t *pud; 84 pmd_t *pmd; 85 pte_t *pte; 86 87 if (pgd_none(*pgd) || pgd_bad(*pgd)) 88 break; 89 90 pud = pud_offset(pgd, addr); 91 printk(", *pud=%016llx", pud_val(*pud)); 92 if (pud_none(*pud) || pud_bad(*pud)) 93 break; 94 95 pmd = pmd_offset(pud, addr); 96 printk(", *pmd=%016llx", pmd_val(*pmd)); 97 if (pmd_none(*pmd) || pmd_bad(*pmd)) 98 break; 99 100 pte = pte_offset_map(pmd, addr); 101 printk(", *pte=%016llx", pte_val(*pte)); 102 pte_unmap(pte); 103 } while(0); 104 105 printk("\n"); 106 } 107 108 #ifdef CONFIG_ARM64_HW_AFDBM 109 /* 110 * This function sets the access flags (dirty, accessed), as well as write 111 * permission, and only to a more permissive setting. 112 * 113 * It needs to cope with hardware update of the accessed/dirty state by other 114 * agents in the system and can safely skip the __sync_icache_dcache() call as, 115 * like set_pte_at(), the PTE is never changed from no-exec to exec here. 116 * 117 * Returns whether or not the PTE actually changed. 118 */ 119 int ptep_set_access_flags(struct vm_area_struct *vma, 120 unsigned long address, pte_t *ptep, 121 pte_t entry, int dirty) 122 { 123 pteval_t old_pteval; 124 unsigned int tmp; 125 126 if (pte_same(*ptep, entry)) 127 return 0; 128 129 /* only preserve the access flags and write permission */ 130 pte_val(entry) &= PTE_AF | PTE_WRITE | PTE_DIRTY; 131 132 /* 133 * PTE_RDONLY is cleared by default in the asm below, so set it in 134 * back if necessary (read-only or clean PTE). 135 */ 136 if (!pte_write(entry) || !pte_sw_dirty(entry)) 137 pte_val(entry) |= PTE_RDONLY; 138 139 /* 140 * Setting the flags must be done atomically to avoid racing with the 141 * hardware update of the access/dirty state. 142 */ 143 asm volatile("// ptep_set_access_flags\n" 144 " prfm pstl1strm, %2\n" 145 "1: ldxr %0, %2\n" 146 " and %0, %0, %3 // clear PTE_RDONLY\n" 147 " orr %0, %0, %4 // set flags\n" 148 " stxr %w1, %0, %2\n" 149 " cbnz %w1, 1b\n" 150 : "=&r" (old_pteval), "=&r" (tmp), "+Q" (pte_val(*ptep)) 151 : "L" (~PTE_RDONLY), "r" (pte_val(entry))); 152 153 flush_tlb_fix_spurious_fault(vma, address); 154 return 1; 155 } 156 #endif 157 158 static bool is_el1_instruction_abort(unsigned int esr) 159 { 160 return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR; 161 } 162 163 /* 164 * The kernel tried to access some page that wasn't present. 165 */ 166 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr, 167 unsigned int esr, struct pt_regs *regs) 168 { 169 /* 170 * Are we prepared to handle this kernel fault? 171 * We are almost certainly not prepared to handle instruction faults. 172 */ 173 if (!is_el1_instruction_abort(esr) && fixup_exception(regs)) 174 return; 175 176 /* 177 * No handler, we'll have to terminate things with extreme prejudice. 178 */ 179 bust_spinlocks(1); 180 pr_alert("Unable to handle kernel %s at virtual address %08lx\n", 181 (addr < PAGE_SIZE) ? "NULL pointer dereference" : 182 "paging request", addr); 183 184 show_pte(mm, addr); 185 die("Oops", regs, esr); 186 bust_spinlocks(0); 187 do_exit(SIGKILL); 188 } 189 190 /* 191 * Something tried to access memory that isn't in our memory map. User mode 192 * accesses just cause a SIGSEGV 193 */ 194 static void __do_user_fault(struct task_struct *tsk, unsigned long addr, 195 unsigned int esr, unsigned int sig, int code, 196 struct pt_regs *regs) 197 { 198 struct siginfo si; 199 200 if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) { 201 pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n", 202 tsk->comm, task_pid_nr(tsk), fault_name(esr), sig, 203 addr, esr); 204 show_pte(tsk->mm, addr); 205 show_regs(regs); 206 } 207 208 tsk->thread.fault_address = addr; 209 tsk->thread.fault_code = esr; 210 si.si_signo = sig; 211 si.si_errno = 0; 212 si.si_code = code; 213 si.si_addr = (void __user *)addr; 214 force_sig_info(sig, &si, tsk); 215 } 216 217 static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs) 218 { 219 struct task_struct *tsk = current; 220 struct mm_struct *mm = tsk->active_mm; 221 222 /* 223 * If we are in kernel mode at this point, we have no context to 224 * handle this fault with. 225 */ 226 if (user_mode(regs)) 227 __do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs); 228 else 229 __do_kernel_fault(mm, addr, esr, regs); 230 } 231 232 #define VM_FAULT_BADMAP 0x010000 233 #define VM_FAULT_BADACCESS 0x020000 234 235 static int __do_page_fault(struct mm_struct *mm, unsigned long addr, 236 unsigned int mm_flags, unsigned long vm_flags, 237 struct task_struct *tsk) 238 { 239 struct vm_area_struct *vma; 240 int fault; 241 242 vma = find_vma(mm, addr); 243 fault = VM_FAULT_BADMAP; 244 if (unlikely(!vma)) 245 goto out; 246 if (unlikely(vma->vm_start > addr)) 247 goto check_stack; 248 249 /* 250 * Ok, we have a good vm_area for this memory access, so we can handle 251 * it. 252 */ 253 good_area: 254 /* 255 * Check that the permissions on the VMA allow for the fault which 256 * occurred. 257 */ 258 if (!(vma->vm_flags & vm_flags)) { 259 fault = VM_FAULT_BADACCESS; 260 goto out; 261 } 262 263 return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags); 264 265 check_stack: 266 if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr)) 267 goto good_area; 268 out: 269 return fault; 270 } 271 272 static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs) 273 { 274 unsigned int ec = ESR_ELx_EC(esr); 275 unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE; 276 277 if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR) 278 return false; 279 280 if (system_uses_ttbr0_pan()) 281 return fsc_type == ESR_ELx_FSC_FAULT && 282 (regs->pstate & PSR_PAN_BIT); 283 else 284 return fsc_type == ESR_ELx_FSC_PERM; 285 } 286 287 static bool is_el0_instruction_abort(unsigned int esr) 288 { 289 return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW; 290 } 291 292 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, 293 struct pt_regs *regs) 294 { 295 struct task_struct *tsk; 296 struct mm_struct *mm; 297 int fault, sig, code; 298 unsigned long vm_flags = VM_READ | VM_WRITE; 299 unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; 300 301 if (notify_page_fault(regs, esr)) 302 return 0; 303 304 tsk = current; 305 mm = tsk->mm; 306 307 /* 308 * If we're in an interrupt or have no user context, we must not take 309 * the fault. 310 */ 311 if (faulthandler_disabled() || !mm) 312 goto no_context; 313 314 if (user_mode(regs)) 315 mm_flags |= FAULT_FLAG_USER; 316 317 if (is_el0_instruction_abort(esr)) { 318 vm_flags = VM_EXEC; 319 } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) { 320 vm_flags = VM_WRITE; 321 mm_flags |= FAULT_FLAG_WRITE; 322 } 323 324 if (addr < USER_DS && is_permission_fault(esr, regs)) { 325 /* regs->orig_addr_limit may be 0 if we entered from EL0 */ 326 if (regs->orig_addr_limit == KERNEL_DS) 327 die("Accessing user space memory with fs=KERNEL_DS", regs, esr); 328 329 if (is_el1_instruction_abort(esr)) 330 die("Attempting to execute userspace memory", regs, esr); 331 332 if (!search_exception_tables(regs->pc)) 333 die("Accessing user space memory outside uaccess.h routines", regs, esr); 334 } 335 336 /* 337 * As per x86, we may deadlock here. However, since the kernel only 338 * validly references user space from well defined areas of the code, 339 * we can bug out early if this is from code which shouldn't. 340 */ 341 if (!down_read_trylock(&mm->mmap_sem)) { 342 if (!user_mode(regs) && !search_exception_tables(regs->pc)) 343 goto no_context; 344 retry: 345 down_read(&mm->mmap_sem); 346 } else { 347 /* 348 * The above down_read_trylock() might have succeeded in which 349 * case, we'll have missed the might_sleep() from down_read(). 350 */ 351 might_sleep(); 352 #ifdef CONFIG_DEBUG_VM 353 if (!user_mode(regs) && !search_exception_tables(regs->pc)) 354 goto no_context; 355 #endif 356 } 357 358 fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk); 359 360 /* 361 * If we need to retry but a fatal signal is pending, handle the 362 * signal first. We do not need to release the mmap_sem because it 363 * would already be released in __lock_page_or_retry in mm/filemap.c. 364 */ 365 if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) 366 return 0; 367 368 /* 369 * Major/minor page fault accounting is only done on the initial 370 * attempt. If we go through a retry, it is extremely likely that the 371 * page will be found in page cache at that point. 372 */ 373 374 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); 375 if (mm_flags & FAULT_FLAG_ALLOW_RETRY) { 376 if (fault & VM_FAULT_MAJOR) { 377 tsk->maj_flt++; 378 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, 379 addr); 380 } else { 381 tsk->min_flt++; 382 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, 383 addr); 384 } 385 if (fault & VM_FAULT_RETRY) { 386 /* 387 * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of 388 * starvation. 389 */ 390 mm_flags &= ~FAULT_FLAG_ALLOW_RETRY; 391 mm_flags |= FAULT_FLAG_TRIED; 392 goto retry; 393 } 394 } 395 396 up_read(&mm->mmap_sem); 397 398 /* 399 * Handle the "normal" case first - VM_FAULT_MAJOR 400 */ 401 if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP | 402 VM_FAULT_BADACCESS)))) 403 return 0; 404 405 /* 406 * If we are in kernel mode at this point, we have no context to 407 * handle this fault with. 408 */ 409 if (!user_mode(regs)) 410 goto no_context; 411 412 if (fault & VM_FAULT_OOM) { 413 /* 414 * We ran out of memory, call the OOM killer, and return to 415 * userspace (which will retry the fault, or kill us if we got 416 * oom-killed). 417 */ 418 pagefault_out_of_memory(); 419 return 0; 420 } 421 422 if (fault & VM_FAULT_SIGBUS) { 423 /* 424 * We had some memory, but were unable to successfully fix up 425 * this page fault. 426 */ 427 sig = SIGBUS; 428 code = BUS_ADRERR; 429 } else { 430 /* 431 * Something tried to access memory that isn't in our memory 432 * map. 433 */ 434 sig = SIGSEGV; 435 code = fault == VM_FAULT_BADACCESS ? 436 SEGV_ACCERR : SEGV_MAPERR; 437 } 438 439 __do_user_fault(tsk, addr, esr, sig, code, regs); 440 return 0; 441 442 no_context: 443 __do_kernel_fault(mm, addr, esr, regs); 444 return 0; 445 } 446 447 /* 448 * First Level Translation Fault Handler 449 * 450 * We enter here because the first level page table doesn't contain a valid 451 * entry for the address. 452 * 453 * If the address is in kernel space (>= TASK_SIZE), then we are probably 454 * faulting in the vmalloc() area. 455 * 456 * If the init_task's first level page tables contains the relevant entry, we 457 * copy the it to this task. If not, we send the process a signal, fixup the 458 * exception, or oops the kernel. 459 * 460 * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt 461 * or a critical region, and should only copy the information from the master 462 * page table, nothing more. 463 */ 464 static int __kprobes do_translation_fault(unsigned long addr, 465 unsigned int esr, 466 struct pt_regs *regs) 467 { 468 if (addr < TASK_SIZE) 469 return do_page_fault(addr, esr, regs); 470 471 do_bad_area(addr, esr, regs); 472 return 0; 473 } 474 475 static int do_alignment_fault(unsigned long addr, unsigned int esr, 476 struct pt_regs *regs) 477 { 478 do_bad_area(addr, esr, regs); 479 return 0; 480 } 481 482 /* 483 * This abort handler always returns "fault". 484 */ 485 static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs) 486 { 487 return 1; 488 } 489 490 static const struct fault_info { 491 int (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs); 492 int sig; 493 int code; 494 const char *name; 495 } fault_info[] = { 496 { do_bad, SIGBUS, 0, "ttbr address size fault" }, 497 { do_bad, SIGBUS, 0, "level 1 address size fault" }, 498 { do_bad, SIGBUS, 0, "level 2 address size fault" }, 499 { do_bad, SIGBUS, 0, "level 3 address size fault" }, 500 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 0 translation fault" }, 501 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" }, 502 { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" }, 503 { do_page_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" }, 504 { do_bad, SIGBUS, 0, "unknown 8" }, 505 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" }, 506 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" }, 507 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 access flag fault" }, 508 { do_bad, SIGBUS, 0, "unknown 12" }, 509 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 permission fault" }, 510 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 permission fault" }, 511 { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 3 permission fault" }, 512 { do_bad, SIGBUS, 0, "synchronous external abort" }, 513 { do_bad, SIGBUS, 0, "unknown 17" }, 514 { do_bad, SIGBUS, 0, "unknown 18" }, 515 { do_bad, SIGBUS, 0, "unknown 19" }, 516 { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" }, 517 { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" }, 518 { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" }, 519 { do_bad, SIGBUS, 0, "synchronous external abort (translation table walk)" }, 520 { do_bad, SIGBUS, 0, "synchronous parity error" }, 521 { do_bad, SIGBUS, 0, "unknown 25" }, 522 { do_bad, SIGBUS, 0, "unknown 26" }, 523 { do_bad, SIGBUS, 0, "unknown 27" }, 524 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" }, 525 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" }, 526 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" }, 527 { do_bad, SIGBUS, 0, "synchronous parity error (translation table walk)" }, 528 { do_bad, SIGBUS, 0, "unknown 32" }, 529 { do_alignment_fault, SIGBUS, BUS_ADRALN, "alignment fault" }, 530 { do_bad, SIGBUS, 0, "unknown 34" }, 531 { do_bad, SIGBUS, 0, "unknown 35" }, 532 { do_bad, SIGBUS, 0, "unknown 36" }, 533 { do_bad, SIGBUS, 0, "unknown 37" }, 534 { do_bad, SIGBUS, 0, "unknown 38" }, 535 { do_bad, SIGBUS, 0, "unknown 39" }, 536 { do_bad, SIGBUS, 0, "unknown 40" }, 537 { do_bad, SIGBUS, 0, "unknown 41" }, 538 { do_bad, SIGBUS, 0, "unknown 42" }, 539 { do_bad, SIGBUS, 0, "unknown 43" }, 540 { do_bad, SIGBUS, 0, "unknown 44" }, 541 { do_bad, SIGBUS, 0, "unknown 45" }, 542 { do_bad, SIGBUS, 0, "unknown 46" }, 543 { do_bad, SIGBUS, 0, "unknown 47" }, 544 { do_bad, SIGBUS, 0, "TLB conflict abort" }, 545 { do_bad, SIGBUS, 0, "unknown 49" }, 546 { do_bad, SIGBUS, 0, "unknown 50" }, 547 { do_bad, SIGBUS, 0, "unknown 51" }, 548 { do_bad, SIGBUS, 0, "implementation fault (lockdown abort)" }, 549 { do_bad, SIGBUS, 0, "implementation fault (unsupported exclusive)" }, 550 { do_bad, SIGBUS, 0, "unknown 54" }, 551 { do_bad, SIGBUS, 0, "unknown 55" }, 552 { do_bad, SIGBUS, 0, "unknown 56" }, 553 { do_bad, SIGBUS, 0, "unknown 57" }, 554 { do_bad, SIGBUS, 0, "unknown 58" }, 555 { do_bad, SIGBUS, 0, "unknown 59" }, 556 { do_bad, SIGBUS, 0, "unknown 60" }, 557 { do_bad, SIGBUS, 0, "section domain fault" }, 558 { do_bad, SIGBUS, 0, "page domain fault" }, 559 { do_bad, SIGBUS, 0, "unknown 63" }, 560 }; 561 562 static const char *fault_name(unsigned int esr) 563 { 564 const struct fault_info *inf = fault_info + (esr & 63); 565 return inf->name; 566 } 567 568 /* 569 * Dispatch a data abort to the relevant handler. 570 */ 571 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr, 572 struct pt_regs *regs) 573 { 574 const struct fault_info *inf = fault_info + (esr & 63); 575 struct siginfo info; 576 577 if (!inf->fn(addr, esr, regs)) 578 return; 579 580 pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n", 581 inf->name, esr, addr); 582 583 info.si_signo = inf->sig; 584 info.si_errno = 0; 585 info.si_code = inf->code; 586 info.si_addr = (void __user *)addr; 587 arm64_notify_die("", regs, &info, esr); 588 } 589 590 /* 591 * Handle stack alignment exceptions. 592 */ 593 asmlinkage void __exception do_sp_pc_abort(unsigned long addr, 594 unsigned int esr, 595 struct pt_regs *regs) 596 { 597 struct siginfo info; 598 struct task_struct *tsk = current; 599 600 if (show_unhandled_signals && unhandled_signal(tsk, SIGBUS)) 601 pr_info_ratelimited("%s[%d]: %s exception: pc=%p sp=%p\n", 602 tsk->comm, task_pid_nr(tsk), 603 esr_get_class_string(esr), (void *)regs->pc, 604 (void *)regs->sp); 605 606 info.si_signo = SIGBUS; 607 info.si_errno = 0; 608 info.si_code = BUS_ADRALN; 609 info.si_addr = (void __user *)addr; 610 arm64_notify_die("Oops - SP/PC alignment exception", regs, &info, esr); 611 } 612 613 int __init early_brk64(unsigned long addr, unsigned int esr, 614 struct pt_regs *regs); 615 616 /* 617 * __refdata because early_brk64 is __init, but the reference to it is 618 * clobbered at arch_initcall time. 619 * See traps.c and debug-monitors.c:debug_traps_init(). 620 */ 621 static struct fault_info __refdata debug_fault_info[] = { 622 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware breakpoint" }, 623 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware single-step" }, 624 { do_bad, SIGTRAP, TRAP_HWBKPT, "hardware watchpoint" }, 625 { do_bad, SIGBUS, 0, "unknown 3" }, 626 { do_bad, SIGTRAP, TRAP_BRKPT, "aarch32 BKPT" }, 627 { do_bad, SIGTRAP, 0, "aarch32 vector catch" }, 628 { early_brk64, SIGTRAP, TRAP_BRKPT, "aarch64 BRK" }, 629 { do_bad, SIGBUS, 0, "unknown 7" }, 630 }; 631 632 void __init hook_debug_fault_code(int nr, 633 int (*fn)(unsigned long, unsigned int, struct pt_regs *), 634 int sig, int code, const char *name) 635 { 636 BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info)); 637 638 debug_fault_info[nr].fn = fn; 639 debug_fault_info[nr].sig = sig; 640 debug_fault_info[nr].code = code; 641 debug_fault_info[nr].name = name; 642 } 643 644 asmlinkage int __exception do_debug_exception(unsigned long addr, 645 unsigned int esr, 646 struct pt_regs *regs) 647 { 648 const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr); 649 struct siginfo info; 650 int rv; 651 652 /* 653 * Tell lockdep we disabled irqs in entry.S. Do nothing if they were 654 * already disabled to preserve the last enabled/disabled addresses. 655 */ 656 if (interrupts_enabled(regs)) 657 trace_hardirqs_off(); 658 659 if (!inf->fn(addr, esr, regs)) { 660 rv = 1; 661 } else { 662 pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n", 663 inf->name, esr, addr); 664 665 info.si_signo = inf->sig; 666 info.si_errno = 0; 667 info.si_code = inf->code; 668 info.si_addr = (void __user *)addr; 669 arm64_notify_die("", regs, &info, 0); 670 rv = 0; 671 } 672 673 if (interrupts_enabled(regs)) 674 trace_hardirqs_on(); 675 676 return rv; 677 } 678 NOKPROBE_SYMBOL(do_debug_exception); 679 680 #ifdef CONFIG_ARM64_PAN 681 int cpu_enable_pan(void *__unused) 682 { 683 /* 684 * We modify PSTATE. This won't work from irq context as the PSTATE 685 * is discarded once we return from the exception. 686 */ 687 WARN_ON_ONCE(in_interrupt()); 688 689 config_sctlr_el1(SCTLR_EL1_SPAN, 0); 690 asm(SET_PSTATE_PAN(1)); 691 return 0; 692 } 693 #endif /* CONFIG_ARM64_PAN */ 694 695 #ifdef CONFIG_ARM64_UAO 696 /* 697 * Kernel threads have fs=KERNEL_DS by default, and don't need to call 698 * set_fs(), devtmpfs in particular relies on this behaviour. 699 * We need to enable the feature at runtime (instead of adding it to 700 * PSR_MODE_EL1h) as the feature may not be implemented by the cpu. 701 */ 702 int cpu_enable_uao(void *__unused) 703 { 704 asm(SET_PSTATE_UAO(1)); 705 return 0; 706 } 707 #endif /* CONFIG_ARM64_UAO */ 708