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
  45 static const char *handler[]= {
  46         "Synchronous Abort",
  47         "IRQ",
  48         "FIQ",
  49         "Error"
  50 };
  51
  52 int show_unhandled_signals = 0;
  53
  54 /*
  55  * Dump out the contents of some memory nicely...
  56  */
  57 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
  58                      unsigned long top, bool compat)
  59 {
  60         unsigned long first;
  61         mm_segment_t fs;
  62         int i;
  63         unsigned int width = compat ? 4 : 8;
  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 / width)
  82                                         && p < top; i++, p += width) {
  83                         if (p >= bottom && p < top) {
  84                                 unsigned long val;
  85
  86                                 if (width == 8) {
  87                                         if (__get_user(val, (unsigned long *)p) == 0)
  88                                                 sprintf(str + i * 17, " %016lx", val);
  89                                         else
  90                                                 sprintf(str + i * 17, " ????????????????");
  91                                 } else {
  92                                         if (__get_user(val, (unsigned int *)p) == 0)
  93                                                 sprintf(str + i * 9, " %08lx", val);
  94                                         else
  95                                                 sprintf(str + i * 9, " ????????");
  96                                 }
  97                         }
  98                 }
  99                 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
 100         }
 101
 102         set_fs(fs);
 103 }
 104
 105 static void dump_backtrace_entry(unsigned long where)
 106 {
 107         /*
 108          * Note that 'where' can have a physical address, but it's not handled.
 109          */
 110         print_ip_sym(where);
 111 }
 112
 113 static void __dump_instr(const char *lvl, struct pt_regs *regs)
 114 {
 115         unsigned long addr = instruction_pointer(regs);
 116         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 117         int i;
 118
 119         for (i = -4; i < 1; i++) {
 120                 unsigned int val, bad;
 121
 122                 bad = get_user(val, &((u32 *)addr)[i]);
 123
 124                 if (!bad)
 125                         p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
 126                 else {
 127                         p += sprintf(p, "bad PC value");
 128                         break;
 129                 }
 130         }
 131         printk("%sCode: %s\n", lvl, str);
 132 }
 133
 134 static void dump_instr(const char *lvl, struct pt_regs *regs)
 135 {
 136         if (!user_mode(regs)) {
 137                 mm_segment_t fs = get_fs();
 138                 set_fs(KERNEL_DS);
 139                 __dump_instr(lvl, regs);
 140                 set_fs(fs);
 141         } else {
 142                 __dump_instr(lvl, regs);
 143         }
 144 }
 145
 146 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 147 {
 148         struct stackframe frame;
 149
 150         pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
 151
 152         if (!tsk)
 153                 tsk = current;
 154
 155         if (regs) {
 156                 frame.fp = regs->regs[29];
 157                 frame.sp = regs->sp;
 158                 frame.pc = regs->pc;
 159         } else 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
 172         pr_emerg("Call trace:\n");
 173         while (1) {
 174                 unsigned long where = frame.pc;
 175                 unsigned long stack;
 176                 int ret;
 177
 178                 dump_backtrace_entry(where);
 179                 ret = unwind_frame(&frame);
 180                 if (ret < 0)
 181                         break;
 182                 stack = frame.sp;
 183                 if (in_exception_text(where))
 184                         dump_mem("", "Exception stack", stack,
 185                                  stack + sizeof(struct pt_regs), false);
 186         }
 187 }
 188
 189 void show_stack(struct task_struct *tsk, unsigned long *sp)
 190 {
 191         dump_backtrace(NULL, tsk);
 192         barrier();
 193 }
 194
 195 #ifdef CONFIG_PREEMPT
 196 #define S_PREEMPT " PREEMPT"
 197 #else
 198 #define S_PREEMPT ""
 199 #endif
 200 #define S_SMP " SMP"
 201
 202 static int __die(const char *str, int err, struct thread_info *thread,
 203                  struct pt_regs *regs)
 204 {
 205         struct task_struct *tsk = thread->task;
 206         static int die_counter;
 207         int ret;
 208
 209         pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
 210                  str, err, ++die_counter);
 211
 212         /* trap and error numbers are mostly meaningless on ARM */
 213         ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV);
 214         if (ret == NOTIFY_STOP)
 215                 return ret;
 216
 217         print_modules();
 218         __show_regs(regs);
 219         pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
 220                  TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
 221
 222         if (!user_mode(regs) || in_interrupt()) {
 223                 dump_mem(KERN_EMERG, "Stack: ", regs->sp,
 224                          THREAD_SIZE + (unsigned long)task_stack_page(tsk),
 225                          compat_user_mode(regs));
 226                 dump_backtrace(regs, tsk);
 227                 dump_instr(KERN_EMERG, regs);
 228         }
 229
 230         return ret;
 231 }
 232
 233 static DEFINE_RAW_SPINLOCK(die_lock);
 234
 235 /*
 236  * This function is protected against re-entrancy.
 237  */
 238 void die(const char *str, struct pt_regs *regs, int err)
 239 {
 240         struct thread_info *thread = current_thread_info();
 241         int ret;
 242         unsigned long flags;
 243
 244         raw_spin_lock_irqsave(&die_lock, flags);
 245
 246         oops_enter();
 247
 248         console_verbose();
 249         bust_spinlocks(1);
 250         ret = __die(str, err, thread, regs);
 251
 252         if (regs && kexec_should_crash(thread->task))
 253                 crash_kexec(regs);
 254
 255         bust_spinlocks(0);
 256         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 257         oops_exit();
 258
 259         if (in_interrupt())
 260                 panic("Fatal exception in interrupt");
 261         if (panic_on_oops)
 262                 panic("Fatal exception");
 263
 264         raw_spin_unlock_irqrestore(&die_lock, flags);
 265
 266         if (ret != NOTIFY_STOP)
 267                 do_exit(SIGSEGV);
 268 }
 269
 270 void arm64_notify_die(const char *str, struct pt_regs *regs,
 271                       struct siginfo *info, int err)
 272 {
 273         if (user_mode(regs)) {
 274                 current->thread.fault_address = 0;
 275                 current->thread.fault_code = err;
 276                 force_sig_info(info->si_signo, info, current);
 277         } else {
 278                 die(str, regs, err);
 279         }
 280 }
 281
 282 static LIST_HEAD(undef_hook);
 283 static DEFINE_RAW_SPINLOCK(undef_lock);
 284
 285 void register_undef_hook(struct undef_hook *hook)
 286 {
 287         unsigned long flags;
 288
 289         raw_spin_lock_irqsave(&undef_lock, flags);
 290         list_add(&hook->node, &undef_hook);
 291         raw_spin_unlock_irqrestore(&undef_lock, flags);
 292 }
 293
 294 void unregister_undef_hook(struct undef_hook *hook)
 295 {
 296         unsigned long flags;
 297
 298         raw_spin_lock_irqsave(&undef_lock, flags);
 299         list_del(&hook->node);
 300         raw_spin_unlock_irqrestore(&undef_lock, flags);
 301 }
 302
 303 static int call_undef_hook(struct pt_regs *regs)
 304 {
 305         struct undef_hook *hook;
 306         unsigned long flags;
 307         u32 instr;
 308         int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
 309         void __user *pc = (void __user *)instruction_pointer(regs);
 310
 311         if (!user_mode(regs))
 312                 return 1;
 313
 314         if (compat_thumb_mode(regs)) {
 315                 /* 16-bit Thumb instruction */
 316                 if (get_user(instr, (u16 __user *)pc))
 317                         goto exit;
 318                 instr = le16_to_cpu(instr);
 319                 if (aarch32_insn_is_wide(instr)) {
 320                         u32 instr2;
 321
 322                         if (get_user(instr2, (u16 __user *)(pc + 2)))
 323                                 goto exit;
 324                         instr2 = le16_to_cpu(instr2);
 325                         instr = (instr << 16) | instr2;
 326                 }
 327         } else {
 328                 /* 32-bit ARM instruction */
 329                 if (get_user(instr, (u32 __user *)pc))
 330                         goto exit;
 331                 instr = le32_to_cpu(instr);
 332         }
 333
 334         raw_spin_lock_irqsave(&undef_lock, flags);
 335         list_for_each_entry(hook, &undef_hook, node)
 336                 if ((instr & hook->instr_mask) == hook->instr_val &&
 337                         (regs->pstate & hook->pstate_mask) == hook->pstate_val)
 338                         fn = hook->fn;
 339
 340         raw_spin_unlock_irqrestore(&undef_lock, flags);
 341 exit:
 342         return fn ? fn(regs, instr) : 1;
 343 }
 344
 345 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 346 {
 347         siginfo_t info;
 348         void __user *pc = (void __user *)instruction_pointer(regs);
 349
 350         /* check for AArch32 breakpoint instructions */
 351         if (!aarch32_break_handler(regs))
 352                 return;
 353
 354         if (call_undef_hook(regs) == 0)
 355                 return;
 356
 357         if (unhandled_signal(current, SIGILL) && show_unhandled_signals_ratelimited()) {
 358                 pr_info("%s[%d]: undefined instruction: pc=%p\n",
 359                         current->comm, task_pid_nr(current), pc);
 360                 dump_instr(KERN_INFO, regs);
 361         }
 362
 363         info.si_signo = SIGILL;
 364         info.si_errno = 0;
 365         info.si_code  = ILL_ILLOPC;
 366         info.si_addr  = pc;
 367
 368         arm64_notify_die("Oops - undefined instruction", regs, &info, 0);
 369 }
 370
 371 long compat_arm_syscall(struct pt_regs *regs);
 372
 373 asmlinkage long do_ni_syscall(struct pt_regs *regs)
 374 {
 375 #ifdef CONFIG_COMPAT
 376         long ret;
 377         if (is_compat_task()) {
 378                 ret = compat_arm_syscall(regs);
 379                 if (ret != -ENOSYS)
 380                         return ret;
 381         }
 382 #endif
 383
 384         return sys_ni_syscall();
 385 }
 386
 387 static const char *esr_class_str[] = {
 388         [0 ... ESR_ELx_EC_MAX]          = "UNRECOGNIZED EC",
 389         [ESR_ELx_EC_UNKNOWN]            = "Unknown/Uncategorized",
 390         [ESR_ELx_EC_WFx]                = "WFI/WFE",
 391         [ESR_ELx_EC_CP15_32]            = "CP15 MCR/MRC",
 392         [ESR_ELx_EC_CP15_64]            = "CP15 MCRR/MRRC",
 393         [ESR_ELx_EC_CP14_MR]            = "CP14 MCR/MRC",
 394         [ESR_ELx_EC_CP14_LS]            = "CP14 LDC/STC",
 395         [ESR_ELx_EC_FP_ASIMD]           = "ASIMD",
 396         [ESR_ELx_EC_CP10_ID]            = "CP10 MRC/VMRS",
 397         [ESR_ELx_EC_CP14_64]            = "CP14 MCRR/MRRC",
 398         [ESR_ELx_EC_ILL]                = "PSTATE.IL",
 399         [ESR_ELx_EC_SVC32]              = "SVC (AArch32)",
 400         [ESR_ELx_EC_HVC32]              = "HVC (AArch32)",
 401         [ESR_ELx_EC_SMC32]              = "SMC (AArch32)",
 402         [ESR_ELx_EC_SVC64]              = "SVC (AArch64)",
 403         [ESR_ELx_EC_HVC64]              = "HVC (AArch64)",
 404         [ESR_ELx_EC_SMC64]              = "SMC (AArch64)",
 405         [ESR_ELx_EC_SYS64]              = "MSR/MRS (AArch64)",
 406         [ESR_ELx_EC_IMP_DEF]            = "EL3 IMP DEF",
 407         [ESR_ELx_EC_IABT_LOW]           = "IABT (lower EL)",
 408         [ESR_ELx_EC_IABT_CUR]           = "IABT (current EL)",
 409         [ESR_ELx_EC_PC_ALIGN]           = "PC Alignment",
 410         [ESR_ELx_EC_DABT_LOW]           = "DABT (lower EL)",
 411         [ESR_ELx_EC_DABT_CUR]           = "DABT (current EL)",
 412         [ESR_ELx_EC_SP_ALIGN]           = "SP Alignment",
 413         [ESR_ELx_EC_FP_EXC32]           = "FP (AArch32)",
 414         [ESR_ELx_EC_FP_EXC64]           = "FP (AArch64)",
 415         [ESR_ELx_EC_SERROR]             = "SError",
 416         [ESR_ELx_EC_BREAKPT_LOW]        = "Breakpoint (lower EL)",
 417         [ESR_ELx_EC_BREAKPT_CUR]        = "Breakpoint (current EL)",
 418         [ESR_ELx_EC_SOFTSTP_LOW]        = "Software Step (lower EL)",
 419         [ESR_ELx_EC_SOFTSTP_CUR]        = "Software Step (current EL)",
 420         [ESR_ELx_EC_WATCHPT_LOW]        = "Watchpoint (lower EL)",
 421         [ESR_ELx_EC_WATCHPT_CUR]        = "Watchpoint (current EL)",
 422         [ESR_ELx_EC_BKPT32]             = "BKPT (AArch32)",
 423         [ESR_ELx_EC_VECTOR32]           = "Vector catch (AArch32)",
 424         [ESR_ELx_EC_BRK64]              = "BRK (AArch64)",
 425 };
 426
 427 const char *esr_get_class_string(u32 esr)
 428 {
 429         return esr_class_str[esr >> ESR_ELx_EC_SHIFT];
 430 }
 431
 432 /*
 433  * bad_mode handles the impossible case in the exception vector. This is always
 434  * fatal.
 435  */
 436 asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
 437 {
 438         console_verbose();
 439
 440         pr_crit("Bad mode in %s handler detected, code 0x%08x -- %s\n",
 441                 handler[reason], esr, esr_get_class_string(esr));
 442
 443         local_irq_disable();
 444         panic("bad mode");
 445 }
 446
 447 /*
 448  * bad_el0_sync handles unexpected, but potentially recoverable synchronous
 449  * exceptions taken from EL0. Unlike bad_mode, this returns.
 450  */
 451 asmlinkage void bad_el0_sync(struct pt_regs *regs, int reason, unsigned int esr)
 452 {
 453         siginfo_t info;
 454         void __user *pc = (void __user *)instruction_pointer(regs);
 455         console_verbose();
 456
 457         pr_crit("Bad EL0 synchronous exception detected on CPU%d, code 0x%08x -- %s\n",
 458                 smp_processor_id(), esr, esr_get_class_string(esr));
 459         __show_regs(regs);
 460
 461         info.si_signo = SIGILL;
 462         info.si_errno = 0;
 463         info.si_code  = ILL_ILLOPC;
 464         info.si_addr  = pc;
 465
 466         current->thread.fault_address = 0;
 467         current->thread.fault_code = 0;
 468
 469         force_sig_info(info.si_signo, &info, current);
 470 }
 471
 472 void __pte_error(const char *file, int line, unsigned long val)
 473 {
 474         pr_crit("%s:%d: bad pte %016lx.\n", file, line, val);
 475 }
 476
 477 void __pmd_error(const char *file, int line, unsigned long val)
 478 {
 479         pr_crit("%s:%d: bad pmd %016lx.\n", file, line, val);
 480 }
 481
 482 void __pud_error(const char *file, int line, unsigned long val)
 483 {
 484         pr_crit("%s:%d: bad pud %016lx.\n", file, line, val);
 485 }
 486
 487 void __pgd_error(const char *file, int line, unsigned long val)
 488 {
 489         pr_crit("%s:%d: bad pgd %016lx.\n", file, line, val);
 490 }
 491
 492 /* GENERIC_BUG traps */
 493
 494 int is_valid_bugaddr(unsigned long addr)
 495 {
 496         /*
 497          * bug_handler() only called for BRK #BUG_BRK_IMM.
 498          * So the answer is trivial -- any spurious instances with no
 499          * bug table entry will be rejected by report_bug() and passed
 500          * back to the debug-monitors code and handled as a fatal
 501          * unexpected debug exception.
 502          */
 503         return 1;
 504 }
 505
 506 static int bug_handler(struct pt_regs *regs, unsigned int esr)
 507 {
 508         if (user_mode(regs))
 509                 return DBG_HOOK_ERROR;
 510
 511         switch (report_bug(regs->pc, regs)) {
 512         case BUG_TRAP_TYPE_BUG:
 513                 die("Oops - BUG", regs, 0);
 514                 break;
 515
 516         case BUG_TRAP_TYPE_WARN:
 517                 /* Ideally, report_bug() should backtrace for us... but no. */
 518                 dump_backtrace(regs, NULL);
 519                 break;
 520
 521         default:
 522                 /* unknown/unrecognised bug trap type */
 523                 return DBG_HOOK_ERROR;
 524         }
 525
 526         /* If thread survives, skip over the BUG instruction and continue: */
 527         regs->pc += AARCH64_INSN_SIZE;  /* skip BRK and resume */
 528         return DBG_HOOK_HANDLED;
 529 }
 530
 531 static struct break_hook bug_break_hook = {
 532         .esr_val = 0xf2000000 | BUG_BRK_IMM,
 533         .esr_mask = 0xffffffff,
 534         .fn = bug_handler,
 535 };
 536
 537 /*
 538  * Initial handler for AArch64 BRK exceptions
 539  * This handler only used until debug_traps_init().
 540  */
 541 int __init early_brk64(unsigned long addr, unsigned int esr,
 542                 struct pt_regs *regs)
 543 {
 544         return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
 545 }
 546
 547 /* This registration must happen early, before debug_traps_init(). */
 548 void __init trap_init(void)
 549 {
 550         register_break_hook(&bug_break_hook);
 551 }