arch/arm64/kernel/traps.c

   1 /*
   2  * Based on arch/arm/kernel/traps.c
   3  *
   4  * Copyright (C) 1995-2009 Russell King
   5  * Copyright (C) 2012 ARM Ltd.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <linux/bug.h>
  21 #include <linux/signal.h>
  22 #include <linux/personality.h>
  23 #include <linux/kallsyms.h>
  24 #include <linux/spinlock.h>
  25 #include <linux/uaccess.h>
  26 #include <linux/hardirq.h>
  27 #include <linux/kdebug.h>
  28 #include <linux/module.h>
  29 #include <linux/kexec.h>
  30 #include <linux/delay.h>
  31 #include <linux/init.h>
  32 #include <linux/sched.h>
  33 #include <linux/syscalls.h>
  34
  35 #include <asm/atomic.h>
  36 #include <asm/bug.h>
  37 #include <asm/debug-monitors.h>
  38 #include <asm/esr.h>
  39 #include <asm/insn.h>
  40 #include <asm/traps.h>
  41 #include <asm/stacktrace.h>
  42 #include <asm/exception.h>
  43 #include <asm/system_misc.h>
  44 #include <asm/sysreg.h>
  45
  46 static const char *handler[]= {
  47         "Synchronous Abort",
  48         "IRQ",
  49         "FIQ",
  50         "Error"
  51 };
  52
  53 int show_unhandled_signals = 1;
  54
  55 /*
  56  * Dump out the contents of some kernel memory nicely...
  57  */
  58 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
  59                      unsigned long top)
  60 {
  61         unsigned long first;
  62         mm_segment_t fs;
  63         int i;
  64
  65         /*
  66          * We need to switch to kernel mode so that we can use __get_user
  67          * to safely read from kernel space.
  68          */
  69         fs = get_fs();
  70         set_fs(KERNEL_DS);
  71
  72         printk("%s%s(0x%016lx to 0x%016lx)\n", lvl, str, bottom, top);
  73
  74         for (first = bottom & ~31; first < top; first += 32) {
  75                 unsigned long p;
  76                 char str[sizeof(" 12345678") * 8 + 1];
  77
  78                 memset(str, ' ', sizeof(str));
  79                 str[sizeof(str) - 1] = '\0';
  80
  81                 for (p = first, i = 0; i < (32 / 8)
  82                                         && p < top; i++, p += 8) {
  83                         if (p >= bottom && p < top) {
  84                                 unsigned long val;
  85
  86                                 if (__get_user(val, (unsigned long *)p) == 0)
  87                                         sprintf(str + i * 17, " %016lx", val);
  88                                 else
  89                                         sprintf(str + i * 17, " ????????????????");
  90                         }
  91                 }
  92                 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
  93         }
  94
  95         set_fs(fs);
  96 }
  97
  98 static void dump_backtrace_entry(unsigned long where)
  99 {
 100         /*
 101          * Note that 'where' can have a physical address, but it's not handled.
 102          */
 103         print_ip_sym(where);
 104 }
 105
 106 static void __dump_instr(const char *lvl, struct pt_regs *regs)
 107 {
 108         unsigned long addr = instruction_pointer(regs);
 109         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 110         int i;
 111
 112         for (i = -4; i < 1; i++) {
 113                 unsigned int val, bad;
 114
 115                 bad = __get_user(val, &((u32 *)addr)[i]);
 116
 117                 if (!bad)
 118                         p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
 119                 else {
 120                         p += sprintf(p, "bad PC value");
 121                         break;
 122                 }
 123         }
 124         printk("%sCode: %s\n", lvl, str);
 125 }
 126
 127 static void dump_instr(const char *lvl, struct pt_regs *regs)
 128 {
 129         if (!user_mode(regs)) {
 130                 mm_segment_t fs = get_fs();
 131                 set_fs(KERNEL_DS);
 132                 __dump_instr(lvl, regs);
 133                 set_fs(fs);
 134         } else {
 135                 __dump_instr(lvl, regs);
 136         }
 137 }
 138
 139 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 140 {
 141         struct stackframe frame;
 142         unsigned long irq_stack_ptr;
 143         int skip;
 144
 145         /*
 146          * Switching between stacks is valid when tracing current and in
 147          * non-preemptible context.
 148          */
 149         if (tsk == current && !preemptible())
 150                 irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
 151         else
 152                 irq_stack_ptr = 0;
 153
 154         pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
 155
 156         if (!tsk)
 157                 tsk = current;
 158
 159         if (tsk == current) {
 160                 frame.fp = (unsigned long)__builtin_frame_address(0);
 161                 frame.sp = current_stack_pointer;
 162                 frame.pc = (unsigned long)dump_backtrace;
 163         } else {
 164                 /*
 165                  * task blocked in __switch_to
 166                  */
 167                 frame.fp = thread_saved_fp(tsk);
 168                 frame.sp = thread_saved_sp(tsk);
 169                 frame.pc = thread_saved_pc(tsk);
 170         }
 171 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 172         frame.graph = tsk->curr_ret_stack;
 173 #endif
 174
 175         skip = !!regs;
 176         printk("Call trace:\n");
 177         while (1) {
 178                 unsigned long where = frame.pc;
 179                 unsigned long stack;
 180                 int ret;
 181
 182                 /* skip until specified stack frame */
 183                 if (!skip) {
 184                         dump_backtrace_entry(where);
 185                 } else if (frame.fp == regs->regs[29]) {
 186                         skip = 0;
 187                         /*
 188                          * Mostly, this is the case where this function is
 189                          * called in panic/abort. As exception handler's
 190                          * stack frame does not contain the corresponding pc
 191                          * at which an exception has taken place, use regs->pc
 192                          * instead.
 193                          */
 194                         dump_backtrace_entry(regs->pc);
 195                 }
 196                 ret = unwind_frame(tsk, &frame);
 197                 if (ret < 0)
 198                         break;
 199                 stack = frame.sp;
 200                 if (in_exception_text(where)) {
 201                         /*
 202                          * If we switched to the irq_stack before calling this
 203                          * exception handler, then the pt_regs will be on the
 204                          * task stack. The easiest way to tell is if the large
 205                          * pt_regs would overlap with the end of the irq_stack.
 206                          */
 207                         if (stack < irq_stack_ptr &&
 208                             (stack + sizeof(struct pt_regs)) > irq_stack_ptr)
 209                                 stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
 210
 211                         dump_mem("", "Exception stack", stack,
 212                                  stack + sizeof(struct pt_regs));
 213                 }
 214         }
 215 }
 216
 217 void show_stack(struct task_struct *tsk, unsigned long *sp)
 218 {
 219         dump_backtrace(NULL, tsk);
 220         barrier();
 221 }
 222
 223 #ifdef CONFIG_PREEMPT
 224 #define S_PREEMPT " PREEMPT"
 225 #else
 226 #define S_PREEMPT ""
 227 #endif
 228 #define S_SMP " SMP"
 229
 230 static int __die(const char *str, int err, struct thread_info *thread,
 231                  struct pt_regs *regs)
 232 {
 233         struct task_struct *tsk = thread->task;
 234         static int die_counter;
 235         int ret;
 236
 237         pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
 238                  str, err, ++die_counter);
 239
 240         /* trap and error numbers are mostly meaningless on ARM */
 241         ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV);
 242         if (ret == NOTIFY_STOP)
 243                 return ret;
 244
 245         print_modules();
 246         __show_regs(regs);
 247         pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
 248                  TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
 249
 250         if (!user_mode(regs)) {
 251                 dump_mem(KERN_EMERG, "Stack: ", regs->sp,
 252                          THREAD_SIZE + (unsigned long)task_stack_page(tsk));
 253                 dump_backtrace(regs, tsk);
 254                 dump_instr(KERN_EMERG, regs);
 255         }
 256
 257         return ret;
 258 }
 259
 260 static DEFINE_RAW_SPINLOCK(die_lock);
 261
 262 /*
 263  * This function is protected against re-entrancy.
 264  */
 265 void die(const char *str, struct pt_regs *regs, int err)
 266 {
 267         struct thread_info *thread = current_thread_info();
 268         int ret;
 269
 270         oops_enter();
 271
 272         raw_spin_lock_irq(&die_lock);
 273         console_verbose();
 274         bust_spinlocks(1);
 275         ret = __die(str, err, thread, regs);
 276
 277         if (regs && kexec_should_crash(thread->task))
 278                 crash_kexec(regs);
 279
 280         bust_spinlocks(0);
 281         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 282         raw_spin_unlock_irq(&die_lock);
 283         oops_exit();
 284
 285         if (in_interrupt())
 286                 panic("Fatal exception in interrupt");
 287         if (panic_on_oops)
 288                 panic("Fatal exception");
 289         if (ret != NOTIFY_STOP)
 290                 do_exit(SIGSEGV);
 291 }
 292
 293 void arm64_notify_die(const char *str, struct pt_regs *regs,
 294                       struct siginfo *info, int err)
 295 {
 296         if (user_mode(regs)) {
 297                 current->thread.fault_address = 0;
 298                 current->thread.fault_code = err;
 299                 force_sig_info(info->si_signo, info, current);
 300         } else {
 301                 die(str, regs, err);
 302         }
 303 }
 304
 305 static LIST_HEAD(undef_hook);
 306 static DEFINE_RAW_SPINLOCK(undef_lock);
 307
 308 void register_undef_hook(struct undef_hook *hook)
 309 {
 310         unsigned long flags;
 311
 312         raw_spin_lock_irqsave(&undef_lock, flags);
 313         list_add(&hook->node, &undef_hook);
 314         raw_spin_unlock_irqrestore(&undef_lock, flags);
 315 }
 316
 317 void unregister_undef_hook(struct undef_hook *hook)
 318 {
 319         unsigned long flags;
 320
 321         raw_spin_lock_irqsave(&undef_lock, flags);
 322         list_del(&hook->node);
 323         raw_spin_unlock_irqrestore(&undef_lock, flags);
 324 }
 325
 326 static int call_undef_hook(struct pt_regs *regs)
 327 {
 328         struct undef_hook *hook;
 329         unsigned long flags;
 330         u32 instr;
 331         int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
 332         void __user *pc = (void __user *)instruction_pointer(regs);
 333
 334         if (!user_mode(regs))
 335                 return 1;
 336
 337         if (compat_thumb_mode(regs)) {
 338                 /* 16-bit Thumb instruction */
 339                 if (get_user(instr, (u16 __user *)pc))
 340                         goto exit;
 341                 instr = le16_to_cpu(instr);
 342                 if (aarch32_insn_is_wide(instr)) {
 343                         u32 instr2;
 344
 345                         if (get_user(instr2, (u16 __user *)(pc + 2)))
 346                                 goto exit;
 347                         instr2 = le16_to_cpu(instr2);
 348                         instr = (instr << 16) | instr2;
 349                 }
 350         } else {
 351                 /* 32-bit ARM instruction */
 352                 if (get_user(instr, (u32 __user *)pc))
 353                         goto exit;
 354                 instr = le32_to_cpu(instr);
 355         }
 356
 357         raw_spin_lock_irqsave(&undef_lock, flags);
 358         list_for_each_entry(hook, &undef_hook, node)
 359                 if ((instr & hook->instr_mask) == hook->instr_val &&
 360                         (regs->pstate & hook->pstate_mask) == hook->pstate_val)
 361                         fn = hook->fn;
 362
 363         raw_spin_unlock_irqrestore(&undef_lock, flags);
 364 exit:
 365         return fn ? fn(regs, instr) : 1;
 366 }
 367
 368 static void force_signal_inject(int signal, int code, struct pt_regs *regs,
 369                                 unsigned long address)
 370 {
 371         siginfo_t info;
 372         void __user *pc = (void __user *)instruction_pointer(regs);
 373         const char *desc;
 374
 375         switch (signal) {
 376         case SIGILL:
 377                 desc = "undefined instruction";
 378                 break;
 379         case SIGSEGV:
 380                 desc = "illegal memory access";
 381                 break;
 382         default:
 383                 desc = "bad mode";
 384                 break;
 385         }
 386
 387         if (unhandled_signal(current, signal) &&
 388             show_unhandled_signals_ratelimited()) {
 389                 pr_info("%s[%d]: %s: pc=%p\n",
 390                         current->comm, task_pid_nr(current), desc, pc);
 391                 dump_instr(KERN_INFO, regs);
 392         }
 393
 394         info.si_signo = signal;
 395         info.si_errno = 0;
 396         info.si_code  = code;
 397         info.si_addr  = pc;
 398
 399         arm64_notify_die(desc, regs, &info, 0);
 400 }
 401
 402 /*
 403  * Set up process info to signal segmentation fault - called on access error.
 404  */
 405 void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr)
 406 {
 407         int code;
 408
 409         down_read(&current->mm->mmap_sem);
 410         if (find_vma(current->mm, addr) == NULL)
 411                 code = SEGV_MAPERR;
 412         else
 413                 code = SEGV_ACCERR;
 414         up_read(&current->mm->mmap_sem);
 415
 416         force_signal_inject(SIGSEGV, code, regs, addr);
 417 }
 418
 419 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 420 {
 421         /* check for AArch32 breakpoint instructions */
 422         if (!aarch32_break_handler(regs))
 423                 return;
 424
 425         if (call_undef_hook(regs) == 0)
 426                 return;
 427
 428         force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);
 429 }
 430
 431 void cpu_enable_cache_maint_trap(void *__unused)
 432 {
 433         config_sctlr_el1(SCTLR_EL1_UCI, 0);
 434 }
 435
 436 #define __user_cache_maint(insn, address, res)                  \
 437         asm volatile (                                          \
 438                 "1:     " insn ", %1\n"                         \
 439                 "       mov     %w0, #0\n"                      \
 440                 "2:\n"                                          \
 441                 "       .pushsection .fixup,\"ax\"\n"           \
 442                 "       .align  2\n"                            \
 443                 "3:     mov     %w0, %w2\n"                     \
 444                 "       b       2b\n"                           \
 445                 "       .popsection\n"                          \
 446                 _ASM_EXTABLE(1b, 3b)                            \
 447                 : "=r" (res)                                    \
 448                 : "r" (address), "i" (-EFAULT) )
 449
 450 asmlinkage void __exception do_sysinstr(unsigned int esr, struct pt_regs *regs)
 451 {
 452         unsigned long address;
 453         int ret;
 454
 455         /* if this is a write with: Op0=1, Op2=1, Op1=3, CRn=7 */
 456         if ((esr & 0x01fffc01) == 0x0012dc00) {
 457                 int rt = (esr >> 5) & 0x1f;
 458                 int crm = (esr >> 1) & 0x0f;
 459
 460                 address = (rt == 31) ? 0 : regs->regs[rt];
 461
 462                 switch (crm) {
 463                 case 11:                /* DC CVAU, gets promoted */
 464                         __user_cache_maint("dc civac", address, ret);
 465                         break;
 466                 case 10:                /* DC CVAC, gets promoted */
 467                         __user_cache_maint("dc civac", address, ret);
 468                         break;
 469                 case 14:                /* DC CIVAC */
 470                         __user_cache_maint("dc civac", address, ret);
 471                         break;
 472                 case 5:                 /* IC IVAU */
 473                         __user_cache_maint("ic ivau", address, ret);
 474                         break;
 475                 default:
 476                         force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);
 477                         return;
 478                 }
 479         } else {
 480                 force_signal_inject(SIGILL, ILL_ILLOPC, regs, 0);
 481                 return;
 482         }
 483
 484         if (ret)
 485                 arm64_notify_segfault(regs, address);
 486         else
 487                 regs->pc += 4;
 488 }
 489
 490 long compat_arm_syscall(struct pt_regs *regs);
 491
 492 asmlinkage long do_ni_syscall(struct pt_regs *regs)
 493 {
 494 #ifdef CONFIG_COMPAT
 495         long ret;
 496         if (is_compat_task()) {
 497                 ret = compat_arm_syscall(regs);
 498                 if (ret != -ENOSYS)
 499                         return ret;
 500         }
 501 #endif
 502
 503         if (show_unhandled_signals_ratelimited()) {
 504                 pr_info("%s[%d]: syscall %d\n", current->comm,
 505                         task_pid_nr(current), (int)regs->syscallno);
 506                 dump_instr("", regs);
 507                 if (user_mode(regs))
 508                         __show_regs(regs);
 509         }
 510
 511         return sys_ni_syscall();
 512 }
 513
 514 static const char *esr_class_str[] = {
 515         [0 ... ESR_ELx_EC_MAX]          = "UNRECOGNIZED EC",
 516         [ESR_ELx_EC_UNKNOWN]            = "Unknown/Uncategorized",
 517         [ESR_ELx_EC_WFx]                = "WFI/WFE",
 518         [ESR_ELx_EC_CP15_32]            = "CP15 MCR/MRC",
 519         [ESR_ELx_EC_CP15_64]            = "CP15 MCRR/MRRC",
 520         [ESR_ELx_EC_CP14_MR]            = "CP14 MCR/MRC",
 521         [ESR_ELx_EC_CP14_LS]            = "CP14 LDC/STC",
 522         [ESR_ELx_EC_FP_ASIMD]           = "ASIMD",
 523         [ESR_ELx_EC_CP10_ID]            = "CP10 MRC/VMRS",
 524         [ESR_ELx_EC_CP14_64]            = "CP14 MCRR/MRRC",
 525         [ESR_ELx_EC_ILL]                = "PSTATE.IL",
 526         [ESR_ELx_EC_SVC32]              = "SVC (AArch32)",
 527         [ESR_ELx_EC_HVC32]              = "HVC (AArch32)",
 528         [ESR_ELx_EC_SMC32]              = "SMC (AArch32)",
 529         [ESR_ELx_EC_SVC64]              = "SVC (AArch64)",
 530         [ESR_ELx_EC_HVC64]              = "HVC (AArch64)",
 531         [ESR_ELx_EC_SMC64]              = "SMC (AArch64)",
 532         [ESR_ELx_EC_SYS64]              = "MSR/MRS (AArch64)",
 533         [ESR_ELx_EC_IMP_DEF]            = "EL3 IMP DEF",
 534         [ESR_ELx_EC_IABT_LOW]           = "IABT (lower EL)",
 535         [ESR_ELx_EC_IABT_CUR]           = "IABT (current EL)",
 536         [ESR_ELx_EC_PC_ALIGN]           = "PC Alignment",
 537         [ESR_ELx_EC_DABT_LOW]           = "DABT (lower EL)",
 538         [ESR_ELx_EC_DABT_CUR]           = "DABT (current EL)",
 539         [ESR_ELx_EC_SP_ALIGN]           = "SP Alignment",
 540         [ESR_ELx_EC_FP_EXC32]           = "FP (AArch32)",
 541         [ESR_ELx_EC_FP_EXC64]           = "FP (AArch64)",
 542         [ESR_ELx_EC_SERROR]             = "SError",
 543         [ESR_ELx_EC_BREAKPT_LOW]        = "Breakpoint (lower EL)",
 544         [ESR_ELx_EC_BREAKPT_CUR]        = "Breakpoint (current EL)",
 545         [ESR_ELx_EC_SOFTSTP_LOW]        = "Software Step (lower EL)",
 546         [ESR_ELx_EC_SOFTSTP_CUR]        = "Software Step (current EL)",
 547         [ESR_ELx_EC_WATCHPT_LOW]        = "Watchpoint (lower EL)",
 548         [ESR_ELx_EC_WATCHPT_CUR]        = "Watchpoint (current EL)",
 549         [ESR_ELx_EC_BKPT32]             = "BKPT (AArch32)",
 550         [ESR_ELx_EC_VECTOR32]           = "Vector catch (AArch32)",
 551         [ESR_ELx_EC_BRK64]              = "BRK (AArch64)",
 552 };
 553
 554 const char *esr_get_class_string(u32 esr)
 555 {
 556         return esr_class_str[ESR_ELx_EC(esr)];
 557 }
 558
 559 /*
 560  * bad_mode handles the impossible case in the exception vector.
 561  */
 562 asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
 563 {
 564         siginfo_t info;
 565         void __user *pc = (void __user *)instruction_pointer(regs);
 566         console_verbose();
 567
 568         pr_crit("Bad mode in %s handler detected on CPU%d, code 0x%08x -- %s\n",
 569                 handler[reason], smp_processor_id(), esr,
 570                 esr_get_class_string(esr));
 571         __show_regs(regs);
 572
 573         info.si_signo = SIGILL;
 574         info.si_errno = 0;
 575         info.si_code  = ILL_ILLOPC;
 576         info.si_addr  = pc;
 577
 578         arm64_notify_die("Oops - bad mode", regs, &info, 0);
 579 }
 580
 581 void __pte_error(const char *file, int line, unsigned long val)
 582 {
 583         pr_err("%s:%d: bad pte %016lx.\n", file, line, val);
 584 }
 585
 586 void __pmd_error(const char *file, int line, unsigned long val)
 587 {
 588         pr_err("%s:%d: bad pmd %016lx.\n", file, line, val);
 589 }
 590
 591 void __pud_error(const char *file, int line, unsigned long val)
 592 {
 593         pr_err("%s:%d: bad pud %016lx.\n", file, line, val);
 594 }
 595
 596 void __pgd_error(const char *file, int line, unsigned long val)
 597 {
 598         pr_err("%s:%d: bad pgd %016lx.\n", file, line, val);
 599 }
 600
 601 /* GENERIC_BUG traps */
 602
 603 int is_valid_bugaddr(unsigned long addr)
 604 {
 605         /*
 606          * bug_handler() only called for BRK #BUG_BRK_IMM.
 607          * So the answer is trivial -- any spurious instances with no
 608          * bug table entry will be rejected by report_bug() and passed
 609          * back to the debug-monitors code and handled as a fatal
 610          * unexpected debug exception.
 611          */
 612         return 1;
 613 }
 614
 615 static int bug_handler(struct pt_regs *regs, unsigned int esr)
 616 {
 617         if (user_mode(regs))
 618                 return DBG_HOOK_ERROR;
 619
 620         switch (report_bug(regs->pc, regs)) {
 621         case BUG_TRAP_TYPE_BUG:
 622                 die("Oops - BUG", regs, 0);
 623                 break;
 624
 625         case BUG_TRAP_TYPE_WARN:
 626                 /* Ideally, report_bug() should backtrace for us... but no. */
 627                 dump_backtrace(regs, NULL);
 628                 break;
 629
 630         default:
 631                 /* unknown/unrecognised bug trap type */
 632                 return DBG_HOOK_ERROR;
 633         }
 634
 635         /* If thread survives, skip over the BUG instruction and continue: */
 636         regs->pc += AARCH64_INSN_SIZE;  /* skip BRK and resume */
 637         return DBG_HOOK_HANDLED;
 638 }
 639
 640 static struct break_hook bug_break_hook = {
 641         .esr_val = 0xf2000000 | BUG_BRK_IMM,
 642         .esr_mask = 0xffffffff,
 643         .fn = bug_handler,
 644 };
 645
 646 /*
 647  * Initial handler for AArch64 BRK exceptions
 648  * This handler only used until debug_traps_init().
 649  */
 650 int __init early_brk64(unsigned long addr, unsigned int esr,
 651                 struct pt_regs *regs)
 652 {
 653         return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
 654 }
 655
 656 /* This registration must happen early, before debug_traps_init(). */
 657 void __init trap_init(void)
 658 {
 659         register_break_hook(&bug_break_hook);
 660 }