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