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 static bool is_el1_instruction_abort(unsigned int esr)
 157 {
 158         return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR;
 159 }
 160
 161 /*
 162  * The kernel tried to access some page that wasn't present.
 163  */
 164 static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
 165                               unsigned int esr, struct pt_regs *regs)
 166 {
 167         /*
 168          * Are we prepared to handle this kernel fault?
 169          * We are almost certainly not prepared to handle instruction faults.
 170          */
 171         if (!is_el1_instruction_abort(esr) && fixup_exception(regs))
 172                 return;
 173
 174         /*
 175          * No handler, we'll have to terminate things with extreme prejudice.
 176          */
 177         bust_spinlocks(1);
 178         pr_alert("Unable to handle kernel %s at virtual address %08lx\n",
 179                  (addr < PAGE_SIZE) ? "NULL pointer dereference" :
 180                  "paging request", addr);
 181
 182         show_pte(mm, addr);
 183         die("Oops", regs, esr);
 184         bust_spinlocks(0);
 185         do_exit(SIGKILL);
 186 }
 187
 188 /*
 189  * Something tried to access memory that isn't in our memory map. User mode
 190  * accesses just cause a SIGSEGV
 191  */
 192 static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
 193                             unsigned int esr, unsigned int sig, int code,
 194                             struct pt_regs *regs)
 195 {
 196         struct siginfo si;
 197
 198         if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) {
 199                 pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n",
 200                         tsk->comm, task_pid_nr(tsk), fault_name(esr), sig,
 201                         addr, esr);
 202                 show_pte(tsk->mm, addr);
 203                 show_regs(regs);
 204         }
 205
 206         tsk->thread.fault_address = addr;
 207         tsk->thread.fault_code = esr;
 208         si.si_signo = sig;
 209         si.si_errno = 0;
 210         si.si_code = code;
 211         si.si_addr = (void __user *)addr;
 212         force_sig_info(sig, &si, tsk);
 213 }
 214
 215 static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 216 {
 217         struct task_struct *tsk = current;
 218         struct mm_struct *mm = tsk->active_mm;
 219
 220         /*
 221          * If we are in kernel mode at this point, we have no context to
 222          * handle this fault with.
 223          */
 224         if (user_mode(regs))
 225                 __do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs);
 226         else
 227                 __do_kernel_fault(mm, addr, esr, regs);
 228 }
 229
 230 #define VM_FAULT_BADMAP         0x010000
 231 #define VM_FAULT_BADACCESS      0x020000
 232
 233 static int __do_page_fault(struct mm_struct *mm, unsigned long addr,
 234                            unsigned int mm_flags, unsigned long vm_flags,
 235                            struct task_struct *tsk)
 236 {
 237         struct vm_area_struct *vma;
 238         int fault;
 239
 240         vma = find_vma(mm, addr);
 241         fault = VM_FAULT_BADMAP;
 242         if (unlikely(!vma))
 243                 goto out;
 244         if (unlikely(vma->vm_start > addr))
 245                 goto check_stack;
 246
 247         /*
 248          * Ok, we have a good vm_area for this memory access, so we can handle
 249          * it.
 250          */
 251 good_area:
 252         /*
 253          * Check that the permissions on the VMA allow for the fault which
 254          * occurred.
 255          */
 256         if (!(vma->vm_flags & vm_flags)) {
 257                 fault = VM_FAULT_BADACCESS;
 258                 goto out;
 259         }
 260
 261         return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);
 262
 263 check_stack:
 264         if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
 265                 goto good_area;
 266 out:
 267         return fault;
 268 }
 269
 270 static inline bool is_permission_fault(unsigned int esr)
 271 {
 272         unsigned int ec       = ESR_ELx_EC(esr);
 273         unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
 274
 275         return (ec == ESR_ELx_EC_DABT_CUR && fsc_type == ESR_ELx_FSC_PERM) ||
 276                (ec == ESR_ELx_EC_IABT_CUR && fsc_type == ESR_ELx_FSC_PERM);
 277 }
 278
 279 static bool is_el0_instruction_abort(unsigned int esr)
 280 {
 281         return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW;
 282 }
 283
 284 static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
 285                                    struct pt_regs *regs)
 286 {
 287         struct task_struct *tsk;
 288         struct mm_struct *mm;
 289         int fault, sig, code;
 290         unsigned long vm_flags = VM_READ | VM_WRITE;
 291         unsigned int mm_flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
 292
 293         if (notify_page_fault(regs, esr))
 294                 return 0;
 295
 296         tsk = current;
 297         mm  = tsk->mm;
 298
 299         /*
 300          * If we're in an interrupt or have no user context, we must not take
 301          * the fault.
 302          */
 303         if (faulthandler_disabled() || !mm)
 304                 goto no_context;
 305
 306         if (user_mode(regs))
 307                 mm_flags |= FAULT_FLAG_USER;
 308
 309         if (is_el0_instruction_abort(esr)) {
 310                 vm_flags = VM_EXEC;
 311         } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) {
 312                 vm_flags = VM_WRITE;
 313                 mm_flags |= FAULT_FLAG_WRITE;
 314         }
 315
 316         if (is_permission_fault(esr) && (addr < USER_DS)) {
 317                 /* regs->orig_addr_limit may be 0 if we entered from EL0 */
 318                 if (regs->orig_addr_limit == KERNEL_DS)
 319                         die("Accessing user space memory with fs=KERNEL_DS", regs, esr);
 320
 321                 if (is_el1_instruction_abort(esr))
 322                         die("Attempting to execute userspace memory", regs, esr);
 323
 324                 if (!search_exception_tables(regs->pc))
 325                         die("Accessing user space memory outside uaccess.h routines", regs, esr);
 326         }
 327
 328         /*
 329          * As per x86, we may deadlock here. However, since the kernel only
 330          * validly references user space from well defined areas of the code,
 331          * we can bug out early if this is from code which shouldn't.
 332          */
 333         if (!down_read_trylock(&mm->mmap_sem)) {
 334                 if (!user_mode(regs) && !search_exception_tables(regs->pc))
 335                         goto no_context;
 336 retry:
 337                 down_read(&mm->mmap_sem);
 338         } else {
 339                 /*
 340                  * The above down_read_trylock() might have succeeded in which
 341                  * case, we'll have missed the might_sleep() from down_read().
 342                  */
 343                 might_sleep();
 344 #ifdef CONFIG_DEBUG_VM
 345                 if (!user_mode(regs) && !search_exception_tables(regs->pc))
 346                         goto no_context;
 347 #endif
 348         }
 349
 350         fault = __do_page_fault(mm, addr, mm_flags, vm_flags, tsk);
 351
 352         /*
 353          * If we need to retry but a fatal signal is pending, handle the
 354          * signal first. We do not need to release the mmap_sem because it
 355          * would already be released in __lock_page_or_retry in mm/filemap.c.
 356          */
 357         if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 358                 return 0;
 359
 360         /*
 361          * Major/minor page fault accounting is only done on the initial
 362          * attempt. If we go through a retry, it is extremely likely that the
 363          * page will be found in page cache at that point.
 364          */
 365
 366         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
 367         if (mm_flags & FAULT_FLAG_ALLOW_RETRY) {
 368                 if (fault & VM_FAULT_MAJOR) {
 369                         tsk->maj_flt++;
 370                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs,
 371                                       addr);
 372                 } else {
 373                         tsk->min_flt++;
 374                         perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs,
 375                                       addr);
 376                 }
 377                 if (fault & VM_FAULT_RETRY) {
 378                         /*
 379                          * Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk of
 380                          * starvation.
 381                          */
 382                         mm_flags &= ~FAULT_FLAG_ALLOW_RETRY;
 383                         mm_flags |= FAULT_FLAG_TRIED;
 384                         goto retry;
 385                 }
 386         }
 387
 388         up_read(&mm->mmap_sem);
 389
 390         /*
 391          * Handle the "normal" case first - VM_FAULT_MAJOR
 392          */
 393         if (likely(!(fault & (VM_FAULT_ERROR | VM_FAULT_BADMAP |
 394                               VM_FAULT_BADACCESS))))
 395                 return 0;
 396
 397         /*
 398          * If we are in kernel mode at this point, we have no context to
 399          * handle this fault with.
 400          */
 401         if (!user_mode(regs))
 402                 goto no_context;
 403
 404         if (fault & VM_FAULT_OOM) {
 405                 /*
 406                  * We ran out of memory, call the OOM killer, and return to
 407                  * userspace (which will retry the fault, or kill us if we got
 408                  * oom-killed).
 409                  */
 410                 pagefault_out_of_memory();
 411                 return 0;
 412         }
 413
 414         if (fault & VM_FAULT_SIGBUS) {
 415                 /*
 416                  * We had some memory, but were unable to successfully fix up
 417                  * this page fault.
 418                  */
 419                 sig = SIGBUS;
 420                 code = BUS_ADRERR;
 421         } else {
 422                 /*
 423                  * Something tried to access memory that isn't in our memory
 424                  * map.
 425                  */
 426                 sig = SIGSEGV;
 427                 code = fault == VM_FAULT_BADACCESS ?
 428                         SEGV_ACCERR : SEGV_MAPERR;
 429         }
 430
 431         __do_user_fault(tsk, addr, esr, sig, code, regs);
 432         return 0;
 433
 434 no_context:
 435         __do_kernel_fault(mm, addr, esr, regs);
 436         return 0;
 437 }
 438
 439 /*
 440  * First Level Translation Fault Handler
 441  *
 442  * We enter here because the first level page table doesn't contain a valid
 443  * entry for the address.
 444  *
 445  * If the address is in kernel space (>= TASK_SIZE), then we are probably
 446  * faulting in the vmalloc() area.
 447  *
 448  * If the init_task's first level page tables contains the relevant entry, we
 449  * copy the it to this task.  If not, we send the process a signal, fixup the
 450  * exception, or oops the kernel.
 451  *
 452  * NOTE! We MUST NOT take any locks for this case. We may be in an interrupt
 453  * or a critical region, and should only copy the information from the master
 454  * page table, nothing more.
 455  */
 456 static int __kprobes do_translation_fault(unsigned long addr,
 457                                           unsigned int esr,
 458                                           struct pt_regs *regs)
 459 {
 460         if (addr < TASK_SIZE)
 461                 return do_page_fault(addr, esr, regs);
 462
 463         do_bad_area(addr, esr, regs);
 464         return 0;
 465 }
 466
 467 static int do_alignment_fault(unsigned long addr, unsigned int esr,
 468                               struct pt_regs *regs)
 469 {
 470         do_bad_area(addr, esr, regs);
 471         return 0;
 472 }
 473
 474 /*
 475  * This abort handler always returns "fault".
 476  */
 477 static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 478 {
 479         return 1;
 480 }
 481
 482 static const struct fault_info {
 483         int     (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs);
 484         int     sig;
 485         int     code;
 486         const char *name;
 487 } fault_info[] = {
 488         { do_bad,               SIGBUS,  0,             "ttbr address size fault"       },
 489         { do_bad,               SIGBUS,  0,             "level 1 address size fault"    },
 490         { do_bad,               SIGBUS,  0,             "level 2 address size fault"    },
 491         { do_bad,               SIGBUS,  0,             "level 3 address size fault"    },
 492         { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 0 translation fault"     },
 493         { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 1 translation fault"     },
 494         { do_translation_fault, SIGSEGV, SEGV_MAPERR,   "level 2 translation fault"     },
 495         { do_page_fault,        SIGSEGV, SEGV_MAPERR,   "level 3 translation fault"     },
 496         { do_bad,               SIGBUS,  0,             "unknown 8"                     },
 497         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 1 access flag fault"     },
 498         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 2 access flag fault"     },
 499         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 3 access flag fault"     },
 500         { do_bad,               SIGBUS,  0,             "unknown 12"                    },
 501         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 1 permission fault"      },
 502         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 2 permission fault"      },
 503         { do_page_fault,        SIGSEGV, SEGV_ACCERR,   "level 3 permission fault"      },
 504         { do_bad,               SIGBUS,  0,             "synchronous external abort"    },
 505         { do_bad,               SIGBUS,  0,             "unknown 17"                    },
 506         { do_bad,               SIGBUS,  0,             "unknown 18"                    },
 507         { do_bad,               SIGBUS,  0,             "unknown 19"                    },
 508         { do_bad,               SIGBUS,  0,             "synchronous abort (translation table walk)" },
 509         { do_bad,               SIGBUS,  0,             "synchronous abort (translation table walk)" },
 510         { do_bad,               SIGBUS,  0,             "synchronous abort (translation table walk)" },
 511         { do_bad,               SIGBUS,  0,             "synchronous abort (translation table walk)" },
 512         { do_bad,               SIGBUS,  0,             "synchronous parity error"      },
 513         { do_bad,               SIGBUS,  0,             "unknown 25"                    },
 514         { do_bad,               SIGBUS,  0,             "unknown 26"                    },
 515         { do_bad,               SIGBUS,  0,             "unknown 27"                    },
 516         { do_bad,               SIGBUS,  0,             "synchronous parity error (translation table walk)" },
 517         { do_bad,               SIGBUS,  0,             "synchronous parity error (translation table walk)" },
 518         { do_bad,               SIGBUS,  0,             "synchronous parity error (translation table walk)" },
 519         { do_bad,               SIGBUS,  0,             "synchronous parity error (translation table walk)" },
 520         { do_bad,               SIGBUS,  0,             "unknown 32"                    },
 521         { do_alignment_fault,   SIGBUS,  BUS_ADRALN,    "alignment fault"               },
 522         { do_bad,               SIGBUS,  0,             "unknown 34"                    },
 523         { do_bad,               SIGBUS,  0,             "unknown 35"                    },
 524         { do_bad,               SIGBUS,  0,             "unknown 36"                    },
 525         { do_bad,               SIGBUS,  0,             "unknown 37"                    },
 526         { do_bad,               SIGBUS,  0,             "unknown 38"                    },
 527         { do_bad,               SIGBUS,  0,             "unknown 39"                    },
 528         { do_bad,               SIGBUS,  0,             "unknown 40"                    },
 529         { do_bad,               SIGBUS,  0,             "unknown 41"                    },
 530         { do_bad,               SIGBUS,  0,             "unknown 42"                    },
 531         { do_bad,               SIGBUS,  0,             "unknown 43"                    },
 532         { do_bad,               SIGBUS,  0,             "unknown 44"                    },
 533         { do_bad,               SIGBUS,  0,             "unknown 45"                    },
 534         { do_bad,               SIGBUS,  0,             "unknown 46"                    },
 535         { do_bad,               SIGBUS,  0,             "unknown 47"                    },
 536         { do_bad,               SIGBUS,  0,             "TLB conflict abort"            },
 537         { do_bad,               SIGBUS,  0,             "unknown 49"                    },
 538         { do_bad,               SIGBUS,  0,             "unknown 50"                    },
 539         { do_bad,               SIGBUS,  0,             "unknown 51"                    },
 540         { do_bad,               SIGBUS,  0,             "implementation fault (lockdown abort)" },
 541         { do_bad,               SIGBUS,  0,             "implementation fault (unsupported exclusive)" },
 542         { do_bad,               SIGBUS,  0,             "unknown 54"                    },
 543         { do_bad,               SIGBUS,  0,             "unknown 55"                    },
 544         { do_bad,               SIGBUS,  0,             "unknown 56"                    },
 545         { do_bad,               SIGBUS,  0,             "unknown 57"                    },
 546         { do_bad,               SIGBUS,  0,             "unknown 58"                    },
 547         { do_bad,               SIGBUS,  0,             "unknown 59"                    },
 548         { do_bad,               SIGBUS,  0,             "unknown 60"                    },
 549         { do_bad,               SIGBUS,  0,             "section domain fault"          },
 550         { do_bad,               SIGBUS,  0,             "page domain fault"             },
 551         { do_bad,               SIGBUS,  0,             "unknown 63"                    },
 552 };
 553
 554 static const char *fault_name(unsigned int esr)
 555 {
 556         const struct fault_info *inf = fault_info + (esr & 63);
 557         return inf->name;
 558 }
 559
 560 /*
 561  * Dispatch a data abort to the relevant handler.
 562  */
 563 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
 564                                          struct pt_regs *regs)
 565 {
 566         const struct fault_info *inf = fault_info + (esr & 63);
 567         struct siginfo info;
 568
 569         if (!inf->fn(addr, esr, regs))
 570                 return;
 571
 572         pr_alert("Unhandled fault: %s (0x%08x) at 0x%016lx\n",
 573                  inf->name, esr, addr);
 574
 575         info.si_signo = inf->sig;
 576         info.si_errno = 0;
 577         info.si_code  = inf->code;
 578         info.si_addr  = (void __user *)addr;
 579         arm64_notify_die("", regs, &info, esr);
 580 }
 581
 582 /*
 583  * Handle stack alignment exceptions.
 584  */
 585 asmlinkage void __exception do_sp_pc_abort(unsigned long addr,
 586                                            unsigned int esr,
 587                                            struct pt_regs *regs)
 588 {
 589         struct siginfo info;
 590         struct task_struct *tsk = current;
 591
 592         if (show_unhandled_signals && unhandled_signal(tsk, SIGBUS))
 593                 pr_info_ratelimited("%s[%d]: %s exception: pc=%p sp=%p\n",
 594                                     tsk->comm, task_pid_nr(tsk),
 595                                     esr_get_class_string(esr), (void *)regs->pc,
 596                                     (void *)regs->sp);
 597
 598         info.si_signo = SIGBUS;
 599         info.si_errno = 0;
 600         info.si_code  = BUS_ADRALN;
 601         info.si_addr  = (void __user *)addr;
 602         arm64_notify_die("Oops - SP/PC alignment exception", regs, &info, esr);
 603 }
 604
 605 int __init early_brk64(unsigned long addr, unsigned int esr,
 606                        struct pt_regs *regs);
 607
 608 /*
 609  * __refdata because early_brk64 is __init, but the reference to it is
 610  * clobbered at arch_initcall time.
 611  * See traps.c and debug-monitors.c:debug_traps_init().
 612  */
 613 static struct fault_info __refdata debug_fault_info[] = {
 614         { do_bad,       SIGTRAP,        TRAP_HWBKPT,    "hardware breakpoint"   },
 615         { do_bad,       SIGTRAP,        TRAP_HWBKPT,    "hardware single-step"  },
 616         { do_bad,       SIGTRAP,        TRAP_HWBKPT,    "hardware watchpoint"   },
 617         { do_bad,       SIGBUS,         0,              "unknown 3"             },
 618         { do_bad,       SIGTRAP,        TRAP_BRKPT,     "aarch32 BKPT"          },
 619         { do_bad,       SIGTRAP,        0,              "aarch32 vector catch"  },
 620         { early_brk64,  SIGTRAP,        TRAP_BRKPT,     "aarch64 BRK"           },
 621         { do_bad,       SIGBUS,         0,              "unknown 7"             },
 622 };
 623
 624 void __init hook_debug_fault_code(int nr,
 625                                   int (*fn)(unsigned long, unsigned int, struct pt_regs *),
 626                                   int sig, int code, const char *name)
 627 {
 628         BUG_ON(nr < 0 || nr >= ARRAY_SIZE(debug_fault_info));
 629
 630         debug_fault_info[nr].fn         = fn;
 631         debug_fault_info[nr].sig        = sig;
 632         debug_fault_info[nr].code       = code;
 633         debug_fault_info[nr].name       = name;
 634 }
 635
 636 asmlinkage int __exception do_debug_exception(unsigned long addr,
 637                                               unsigned int esr,
 638                                               struct pt_regs *regs)
 639 {
 640         const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
 641         struct siginfo info;
 642         int rv;
 643
 644         /*
 645          * Tell lockdep we disabled irqs in entry.S. Do nothing if they were
 646          * already disabled to preserve the last enabled/disabled addresses.
 647          */
 648         if (interrupts_enabled(regs))
 649                 trace_hardirqs_off();
 650
 651         if (!inf->fn(addr, esr, regs)) {
 652                 rv = 1;
 653         } else {
 654                 pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
 655                          inf->name, esr, addr);
 656
 657                 info.si_signo = inf->sig;
 658                 info.si_errno = 0;
 659                 info.si_code  = inf->code;
 660                 info.si_addr  = (void __user *)addr;
 661                 arm64_notify_die("", regs, &info, 0);
 662                 rv = 0;
 663         }
 664
 665         if (interrupts_enabled(regs))
 666                 trace_hardirqs_on();
 667
 668         return rv;
 669 }
 670 NOKPROBE_SYMBOL(do_debug_exception);
 671
 672 #ifdef CONFIG_ARM64_PAN
 673 void cpu_enable_pan(void *__unused)
 674 {
 675         config_sctlr_el1(SCTLR_EL1_SPAN, 0);
 676 }
 677 #endif /* CONFIG_ARM64_PAN */
 678
 679 #ifdef CONFIG_ARM64_UAO
 680 /*
 681  * Kernel threads have fs=KERNEL_DS by default, and don't need to call
 682  * set_fs(), devtmpfs in particular relies on this behaviour.
 683  * We need to enable the feature at runtime (instead of adding it to
 684  * PSR_MODE_EL1h) as the feature may not be implemented by the cpu.
 685  */
 686 void cpu_enable_uao(void *__unused)
 687 {
 688         asm(SET_PSTATE_UAO(1));
 689 }
 690 #endif /* CONFIG_ARM64_UAO */