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