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 #ifdef CONFIG_KPROBES
  45 static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
  46 {
  47         int ret = 0;
  48
  49         /* kprobe_running() needs smp_processor_id() */
  50         if (!user_mode(regs)) {
  51                 preempt_disable();
  52                 if (kprobe_running() && kprobe_fault_handler(regs, esr))
  53                         ret = 1;
  54                 preempt_enable();
  55         }
  56
  57         return ret;
  58 }
  59 #else
  60 static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr)
  61 {
  62         return 0;
  63 }
  64 #endif
  65
  66 /*
  67  * Dump out the page tables associated with 'addr' in mm 'mm'.
  68  */
  69 void show_pte(struct mm_struct *mm, unsigned long addr)
  70 {
  71         pgd_t *pgd;
  72
  73         if (!mm)
  74                 mm = &init_mm;
  75
  76         pr_alert("pgd = %p\n", mm->pgd);
  77         pgd = pgd_offset(mm, addr);
  78         pr_alert("[%08lx] *pgd=%016llx", addr, pgd_val(*pgd));
  79
  80         do {
  81                 pud_t *pud;
  82                 pmd_t *pmd;
  83                 pte_t *pte;
  84
  85                 if (pgd_none(*pgd) || pgd_bad(*pgd))
  86                         break;
  87
  88                 pud = pud_offset(pgd, addr);
  89                 printk(", *pud=%016llx", pud_val(*pud));
  90                 if (pud_none(*pud) || pud_bad(*pud))
  91                         break;
  92
  93                 pmd = pmd_offset(pud, addr);
  94                 printk(", *pmd=%016llx", pmd_val(*pmd));
  95                 if (pmd_none(*pmd) || pmd_bad(*pmd))
  96                         break;
  97
  98                 pte = pte_offset_map(pmd, addr);
  99                 printk(", *pte=%016llx", pte_val(*pte));
 100                 pte_unmap(pte);
 101         } while(0);
 102
 103         printk("\n");
 104 }
 105
 106 #ifdef CONFIG_ARM64_HW_AFDBM
 107 /*
 108  * This function sets the access flags (dirty, accessed), as well as write
 109  * permission, and only to a more permissive setting.
 110  *
 111  * It needs to cope with hardware update of the accessed/dirty state by other
 112  * agents in the system and can safely skip the __sync_icache_dcache() call as,
 113  * like set_pte_at(), the PTE is never changed from no-exec to exec here.
 114  *
 115  * Returns whether or not the PTE actually changed.
 116  */
 117 int ptep_set_access_flags(struct vm_area_struct *vma,
 118                           unsigned long address, pte_t *ptep,
 119                           pte_t entry, int dirty)
 120 {
 121         pteval_t old_pteval;
 122         unsigned int tmp;
 123
 124         if (pte_same(*ptep, entry))
 125                 return 0;
 126
 127         /* only preserve the access flags and write permission */
 128         pte_val(entry) &= PTE_AF | PTE_WRITE | PTE_DIRTY;
 129
 130         /*
 131          * PTE_RDONLY is cleared by default in the asm below, so set it in
 132          * back if necessary (read-only or clean PTE).
 133          */
 134         if (!pte_write(entry) || !pte_sw_dirty(entry))
 135                 pte_val(entry) |= PTE_RDONLY;
 136
 137         /*
 138          * Setting the flags must be done atomically to avoid racing with the
 139          * hardware update of the access/dirty state.
 140          */
 141         asm volatile("//        ptep_set_access_flags\n"
 142         "       prfm    pstl1strm, %2\n"
 143         "1:     ldxr    %0, %2\n"
 144         "       and     %0, %0, %3              // clear PTE_RDONLY\n"
 145         "       orr     %0, %0, %4              // set flags\n"
 146         "       stxr    %w1, %0, %2\n"
 147         "       cbnz    %w1, 1b\n"
 148         : "=&r" (old_pteval), "=&r" (tmp), "+Q" (pte_val(*ptep))
 149         : "L" (~PTE_RDONLY), "r" (pte_val(entry)));
 150
 151         flush_tlb_fix_spurious_fault(vma, address);
 152         return 1;
 153 }
 154 #endif
 155
 156 /*
 157  * The kernel tried to access some page that wasn't present.
 158  */
 159 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
 160                               unsigned int esr, struct pt_regs *regs)
 161 {
 162         /*
 163          * Are we prepared to handle this kernel fault?
 164          */
 165         if (fixup_exception(regs))
 166                 return;
 167
 168         /*
 169          * No handler, we'll have to terminate things with extreme prejudice.
 170          */
 171         bust_spinlocks(1);
 172         pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
 173                  (addr < PAGE_SIZE) ? "NULL pointer dereference" :
 174                  "paging request", addr);
 175
 176         show_pte(mm, addr);
 177         die("Oops", regs, esr);
 178         bust_spinlocks(0);
 179         do_exit(SIGKILL);
 180 }
 181
 182 /*
 183  * Something tried to access memory that isn't in our memory map. User mode
 184  * accesses just cause a SIGSEGV
 185  */
 186 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
 187                             unsigned int esr, unsigned int sig, int code,
 188                             struct pt_regs *regs)
 189 {
 190         struct siginfo si;
 191
 192         if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
 193                 pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
 194                         tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
 195                         addr, esr);
 196                 show_pte(tsk->mm, addr);
 197                 show_regs(regs);
 198         }
 199
 200         tsk->thread.fault_address = addr;
 201         tsk->thread.fault_code = esr;
 202         si.si_signo = sig;
 203         si.si_errno = 0;
 204         si.si_code = code;
 205         si.si_addr = (void __user *)addr;
 206         force_sig_info(sig, &si, tsk);
 207 }
 208
 209 static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 210 {
 211         struct task_struct *tsk = current;
 212         struct mm_struct *mm = tsk->active_mm;
 213
 214         /*
 215          * If we are in kernel mode at this point, we have no context to
 216          * handle this fault with.
 217          */
 218         if (user_mode(regs))
 219                 __do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
 220         else
 221                 __do_kernel_fault(mm, addr, esr, regs);
 222 }
 223
 224 #define VM_FAULT_BADMAP         0x010000
 225 #define VM_FAULT_BADACCESS      0x020000
 226
 227 static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
 228                            unsigned int mm_flags, unsigned long vm_flags,
 229                            struct task_struct *tsk)
 230 {
 231         struct vm_area_struct *vma;
 232         int fault;
 233
 234         vma = find_vma(mm, addr);
 235         fault = VM_FAULT_BADMAP;
 236         if (unlikely(!vma))
 237                 goto out;
 238         if (unlikely(vma->vm_start > addr))
 239                 goto check_stack;
 240
 241         /*
 242          * Ok, we have a good vm_area for this memory access, so we can handle
 243          * it.
 244          */
 245 good_area:
 246         /*
 247          * Check that the permissions on the VMA allow for the fault which
 248          * occurred. If we encountered a write or exec fault, we must have
 249          * appropriate permissions, otherwise we allow any permission.
 250          */
 251         if (!(vma->vm_flags & vm_flags)) {
 252                 fault = VM_FAULT_BADACCESS;
 253                 goto out;
 254         }
 255
 256         return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);
 257
 258 check_stack:
 259         if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
 260                 goto good_area;
 261 out:
 262         return fault;
 263 }
 264
 265 static inline bool is_permission_fault(unsigned int esr)
 266 {
 267         unsigned int ec       = ESR_ELx_EC(esr);
 268         unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
 269
 270         return (ec == ESR_ELx_EC_DABT_CUR && fsc_type == ESR_ELx_FSC_PERM);
 271 }
 272
 273 static bool is_el0_instruction_abort(unsigned int esr)
 274 {
 275         return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
 276 }
 277
 278 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
 279                                    struct pt_regs *regs)
 280 {
 281         struct task_struct *tsk;
 282         struct mm_struct *mm;
 283         int fault, sig, code;
 284         unsigned long vm_flags = VM_READ | VM_WRITE | VM_EXEC;
 285         unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 286
 287         if (notify_page_fault(regs, esr))
 288                 return 0;
 289
 290         tsk = current;
 291         mm  = tsk->mm;
 292
 293         /*
 294          * If we're in an interrupt or have no user context, we must not take
 295          * the fault.
 296          */
 297         if (faulthandler_disabled() || !mm)
 298                 goto no_context;
 299
 300         if (user_mode(regs))
 301                 mm_flags |= FAULT_FLAG_USER;
 302
 303         if (is_el0_instruction_abort(esr)) {
 304                 vm_flags = VM_EXEC;
 305         } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
 306                 vm_flags = VM_WRITE;
 307                 mm_flags |= FAULT_FLAG_WRITE;
 308         }
 309
 310         if (is_permission_fault(esr) && (addr < USER_DS)) {
 311                 /* regs->orig_addr_limit may be 0 if we entered from EL0 */
 312                 if (regs->orig_addr_limit == KERNEL_DS)
 313                         die("Accessing user space memory with fs=KERNEL_DS", regs, esr);
 314
 315                 if (!search_exception_tables(regs->pc))
 316                         die("Accessing user space memory outside uaccess.h routines", regs, esr);
 317         }
 318
 319         /*
 320          * As per x86, we may deadlock here. However, since the kernel only
 321          * validly references user space from well defined areas of the code,
 322          * we can bug out early if this is from code which shouldn't.
 323          */
 324         if (!down_read_trylock(&mm->mmap_sem)) {
 325                 if (!user_mode(regs) && !search_exception_tables(regs->pc))
 326                         goto no_context;
 327 retry:
 328                 down_read(&mm->mmap_sem);
 329         } else {
 330                 /*
 331                  * The above down_read_trylock() might have succeeded in which
 332                  * case, we'll have missed the might_sleep() from down_read().
 333                  */
 334                 might_sleep();
 335 #ifdef CONFIG_DEBUG_VM
 336                 if (!user_mode(regs) && !search_exception_tables(regs->pc))
 337                         goto no_context;
 338 #endif
 339         }
 340
 341         fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
 342
 343         /*
 344          * If we need to retry but a fatal signal is pending, handle the
 345          * signal first. We do not need to release the mmap_sem because it
 346          * would already be released in __lock_page_or_retry in mm/filemap.c.
 347          */
 348         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 349                 return 0;
 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
 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 static int do_alignment_fault(unsigned long addr, unsigned int esr,
 459                               struct pt_regs *regs)
 460 {
 461         do_bad_area(addr, esr, regs);
 462         return 0;
 463 }
 464
 465 /*
 466  * This abort handler always returns "fault".
 467  */
 468 static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 469 {
 470         return 1;
 471 }
 472
 473 static const struct fault_info {
 474         int     (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
 475         int     sig;
 476         int     code;
 477         const char *name;
 478 } fault_info[] = {
 479         { do_bad,               SIGBUS,  0,             "ttbr address size fault"       },
 480         { do_bad,               SIGBUS,  0,             "level 1 address size fault"    },
 481         { do_bad,               SIGBUS,  0,             "level 2 address size fault"    },
 482         { do_bad,               SIGBUS,  0,             "level 3 address size fault"    },
 483         { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 0 translation fault"     },
 484         { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 1 translation fault"     },
 485         { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 2 translation fault"     },
 486         { do_page_fault,        SIGSEGV, SEGV_MAPERR,   "level 3 translation fault"     },
 487         { do_bad,               SIGBUS,  0,             "unknown 8"                     },
 488         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 1 access flag fault"     },
 489         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 2 access flag fault"     },
 490         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 3 access flag fault"     },
 491         { do_bad,               SIGBUS,  0,             "unknown 12"                    },
 492         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 1 permission fault"      },
 493         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 2 permission fault"      },
 494         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 3 permission fault"      },
 495         { do_bad,               SIGBUS,  0,             "synchronous external abort"    },
 496         { do_bad,               SIGBUS,  0,             "unknown 17"                    },
 497         { do_bad,               SIGBUS,  0,             "unknown 18"                    },
 498         { do_bad,               SIGBUS,  0,             "unknown 19"                    },
 499         { do_bad,               SIGBUS,  0,             "synchronous abort (translation table walk)" },
 500         { do_bad,               SIGBUS,  0,             "synchronous abort (translation table walk)" },
 501         { do_bad,               SIGBUS,  0,             "synchronous abort (translation table walk)" },
 502         { do_bad,               SIGBUS,  0,             "synchronous abort (translation table walk)" },
 503         { do_bad,               SIGBUS,  0,             "synchronous parity error"      },
 504         { do_bad,               SIGBUS,  0,             "unknown 25"                    },
 505         { do_bad,               SIGBUS,  0,             "unknown 26"                    },
 506         { do_bad,               SIGBUS,  0,             "unknown 27"                    },
 507         { do_bad,               SIGBUS,  0,             "synchronous parity error (translation table walk)" },
 508         { do_bad,               SIGBUS,  0,             "synchronous parity error (translation table walk)" },
 509         { do_bad,               SIGBUS,  0,             "synchronous parity error (translation table walk)" },
 510         { do_bad,               SIGBUS,  0,             "synchronous parity error (translation table walk)" },
 511         { do_bad,               SIGBUS,  0,             "unknown 32"                    },
 512         { do_alignment_fault,   SIGBUS,  BUS_ADRALN,    "alignment fault"               },
 513         { do_bad,               SIGBUS,  0,             "unknown 34"                    },
 514         { do_bad,               SIGBUS,  0,             "unknown 35"                    },
 515         { do_bad,               SIGBUS,  0,             "unknown 36"                    },
 516         { do_bad,               SIGBUS,  0,             "unknown 37"                    },
 517         { do_bad,               SIGBUS,  0,             "unknown 38"                    },
 518         { do_bad,               SIGBUS,  0,             "unknown 39"                    },
 519         { do_bad,               SIGBUS,  0,             "unknown 40"                    },
 520         { do_bad,               SIGBUS,  0,             "unknown 41"                    },
 521         { do_bad,               SIGBUS,  0,             "unknown 42"                    },
 522         { do_bad,               SIGBUS,  0,             "unknown 43"                    },
 523         { do_bad,               SIGBUS,  0,             "unknown 44"                    },
 524         { do_bad,               SIGBUS,  0,             "unknown 45"                    },
 525         { do_bad,               SIGBUS,  0,             "unknown 46"                    },
 526         { do_bad,               SIGBUS,  0,             "unknown 47"                    },
 527         { do_bad,               SIGBUS,  0,             "TLB conflict abort"            },
 528         { do_bad,               SIGBUS,  0,             "unknown 49"                    },
 529         { do_bad,               SIGBUS,  0,             "unknown 50"                    },
 530         { do_bad,               SIGBUS,  0,             "unknown 51"                    },
 531         { do_bad,               SIGBUS,  0,             "implementation fault (lockdown abort)" },
 532         { do_bad,               SIGBUS,  0,             "implementation fault (unsupported exclusive)" },
 533         { do_bad,               SIGBUS,  0,             "unknown 54"                    },
 534         { do_bad,               SIGBUS,  0,             "unknown 55"                    },
 535         { do_bad,               SIGBUS,  0,             "unknown 56"                    },
 536         { do_bad,               SIGBUS,  0,             "unknown 57"                    },
 537         { do_bad,               SIGBUS,  0,             "unknown 58"                    },
 538         { do_bad,               SIGBUS,  0,             "unknown 59"                    },
 539         { do_bad,               SIGBUS,  0,             "unknown 60"                    },
 540         { do_bad,               SIGBUS,  0,             "section domain fault"          },
 541         { do_bad,               SIGBUS,  0,             "page domain fault"             },
 542         { do_bad,               SIGBUS,  0,             "unknown 63"                    },
 543 };
 544
 545 static const char *fault_name(unsigned int esr)
 546 {
 547         const struct fault_info *inf = fault_info + (esr & 63);
 548         return inf->name;
 549 }
 550
 551 /*
 552  * Dispatch a data abort to the relevant handler.
 553  */
 554 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
 555                                          struct pt_regs *regs)
 556 {
 557         const struct fault_info *inf = fault_info + (esr & 63);
 558         struct siginfo info;
 559
 560         if (!inf->fn(addr, esr, regs))
 561                 return;
 562
 563         pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
 564                  inf->name, esr, addr);
 565
 566         info.si_signo = inf->sig;
 567         info.si_errno = 0;
 568         info.si_code  = inf->code;
 569         info.si_addr  = (void __user *)addr;
 570         arm64_notify_die("", regs, &info, esr);
 571 }
 572
 573 /*
 574  * Handle stack alignment exceptions.
 575  */
 576 asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
 577                                            unsigned int esr,
 578                                            struct pt_regs *regs)
 579 {
 580         struct siginfo info;
 581         struct task_struct *tsk = current;
 582
 583         if (show_unhandled_signals && unhandled_signal(tsk, SIGBUS))
 584                 pr_info_ratelimited("%s[%d]: %s exception: pc=%p sp=%p\n",
 585                                     tsk->comm, task_pid_nr(tsk),
 586                                     esr_get_class_string(esr), (void *)regs->pc,
 587                                     (void *)regs->sp);
 588
 589         info.si_signo = SIGBUS;
 590         info.si_errno = 0;
 591         info.si_code  = BUS_ADRALN;
 592         info.si_addr  = (void __user *)addr;
 593         arm64_notify_die("Oops - SP/PC alignment exception", regs, &info, esr);
 594 }
 595
 596 int __init early_brk64(unsigned long addr, unsigned int esr,
 597                        struct pt_regs *regs);
 598
 599 /*
 600  * __refdata because early_brk64 is __init, but the reference to it is
 601  * clobbered at arch_initcall time.
 602  * See traps.c and debug-monitors.c:debug_traps_init().
 603  */
 604 static struct fault_info __refdata debug_fault_info[] = {
 605         { do_bad,       SIGTRAP,        TRAP_HWBKPT,    "hardware breakpoint"   },
 606         { do_bad,       SIGTRAP,        TRAP_HWBKPT,    "hardware single-step"  },
 607         { do_bad,       SIGTRAP,        TRAP_HWBKPT,    "hardware watchpoint"   },
 608         { do_bad,       SIGBUS,         0,              "unknown 3"             },
 609         { do_bad,       SIGTRAP,        TRAP_BRKPT,     "aarch32 BKPT"          },
 610         { do_bad,       SIGTRAP,        0,              "aarch32 vector catch"  },
 611         { early_brk64,  SIGTRAP,        TRAP_BRKPT,     "aarch64 BRK"           },
 612         { do_bad,       SIGBUS,         0,              "unknown 7"             },
 613 };
 614
 615 void __init hook_debug_fault_code(int nr,
 616                                   int (*fn)(unsigned long, unsigned int, struct pt_regs *),
 617                                   int sig, int code, const char *name)
 618 {
 619         BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
 620
 621         debug_fault_info[nr].fn         = fn;
 622         debug_fault_info[nr].sig        = sig;
 623         debug_fault_info[nr].code       = code;
 624         debug_fault_info[nr].name       = name;
 625 }
 626
 627 asmlinkage int __exception do_debug_exception(unsigned long addr,
 628                                               unsigned int esr,
 629                                               struct pt_regs *regs)
 630 {
 631         const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
 632         struct siginfo info;
 633         int rv;
 634
 635         /*
 636          * Tell lockdep we disabled irqs in entry.S. Do nothing if they were
 637          * already disabled to preserve the last enabled/disabled addresses.
 638          */
 639         if (interrupts_enabled(regs))
 640                 trace_hardirqs_off();
 641
 642         if (!inf->fn(addr, esr, regs)) {
 643                 rv = 1;
 644         } else {
 645                 pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
 646                          inf->name, esr, addr);
 647
 648                 info.si_signo = inf->sig;
 649                 info.si_errno = 0;
 650                 info.si_code  = inf->code;
 651                 info.si_addr  = (void __user *)addr;
 652                 arm64_notify_die("", regs, &info, 0);
 653                 rv = 0;
 654         }
 655
 656         if (interrupts_enabled(regs))
 657                 trace_hardirqs_on();
 658
 659         return rv;
 660 }
 661 NOKPROBE_SYMBOL(do_debug_exception);
 662
 663 #ifdef CONFIG_ARM64_PAN
 664 void cpu_enable_pan(void *__unused)
 665 {
 666         config_sctlr_el1(SCTLR_EL1_SPAN, 0);
 667 }
 668 #endif /* CONFIG_ARM64_PAN */
 669
 670 #ifdef CONFIG_ARM64_UAO
 671 /*
 672  * Kernel threads have fs=KERNEL_DS by default, and don't need to call
 673  * set_fs(), devtmpfs in particular relies on this behaviour.
 674  * We need to enable the feature at runtime (instead of adding it to
 675  * PSR_MODE_EL1h) as the feature may not be implemented by the cpu.
 676  */
 677 void cpu_enable_uao(void *__unused)
 678 {
 679         asm(SET_PSTATE_UAO(1));
 680 }
 681 #endif /* CONFIG_ARM64_UAO */