arch/arm64/mm/fault.c

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