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 = 1;
  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.  Note that we now dump the
  68          * code first, just in case the backtrace kills us.
  69          */
  70         fs = get_fs();
  71         set_fs(KERNEL_DS);
  72
  73         printk("%s%s(0x%016lx to 0x%016lx)\n", lvl, str, bottom, top);
  74
  75         for (first = bottom & ~31; first < top; first += 32) {
  76                 unsigned long p;
  77                 char str[sizeof(" 12345678") * 8 + 1];
  78
  79                 memset(str, ' ', sizeof(str));
  80                 str[sizeof(str) - 1] = '\0';
  81
  82                 for (p = first, i = 0; i < (32 / width)
  83                                         && p < top; i++, p += width) {
  84                         if (p >= bottom && p < top) {
  85                                 unsigned long val;
  86
  87                                 if (width == 8) {
  88                                         if (__get_user(val, (unsigned long *)p) == 0)
  89                                                 sprintf(str + i * 17, " %016lx", val);
  90                                         else
  91                                                 sprintf(str + i * 17, " ????????????????");
  92                                 } else {
  93                                         if (__get_user(val, (unsigned int *)p) == 0)
  94                                                 sprintf(str + i * 9, " %08lx", val);
  95                                         else
  96                                                 sprintf(str + i * 9, " ????????");
  97                                 }
  98                         }
  99                 }
 100                 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
 101         }
 102
 103         set_fs(fs);
 104 }
 105
 106 static void dump_backtrace_entry(unsigned long where)
 107 {
 108         /*
 109          * Note that 'where' can have a physical address, but it's not handled.
 110          */
 111         print_ip_sym(where);
 112 }
 113
 114 static void dump_instr(const char *lvl, struct pt_regs *regs)
 115 {
 116         unsigned long addr = instruction_pointer(regs);
 117         mm_segment_t fs;
 118         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 119         int i;
 120
 121         /*
 122          * We need to switch to kernel mode so that we can use __get_user
 123          * to safely read from kernel space.  Note that we now dump the
 124          * code first, just in case the backtrace kills us.
 125          */
 126         fs = get_fs();
 127         set_fs(KERNEL_DS);
 128
 129         for (i = -4; i < 1; i++) {
 130                 unsigned int val, bad;
 131
 132                 bad = __get_user(val, &((u32 *)addr)[i]);
 133
 134                 if (!bad)
 135                         p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
 136                 else {
 137                         p += sprintf(p, "bad PC value");
 138                         break;
 139                 }
 140         }
 141         printk("%sCode: %s\n", lvl, str);
 142
 143         set_fs(fs);
 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
 243         oops_enter();
 244
 245         raw_spin_lock_irq(&die_lock);
 246         console_verbose();
 247         bust_spinlocks(1);
 248         ret = __die(str, err, thread, regs);
 249
 250         if (regs && kexec_should_crash(thread->task))
 251                 crash_kexec(regs);
 252
 253         bust_spinlocks(0);
 254         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 255         raw_spin_unlock_irq(&die_lock);
 256         oops_exit();
 257
 258         if (in_interrupt())
 259                 panic("Fatal exception in interrupt");
 260         if (panic_on_oops)
 261                 panic("Fatal exception");
 262         if (ret != NOTIFY_STOP)
 263                 do_exit(SIGSEGV);
 264 }
 265
 266 void arm64_notify_die(const char *str, struct pt_regs *regs,
 267                       struct siginfo *info, int err)
 268 {
 269         if (user_mode(regs)) {
 270                 current->thread.fault_address = 0;
 271                 current->thread.fault_code = err;
 272                 force_sig_info(info->si_signo, info, current);
 273         } else {
 274                 die(str, regs, err);
 275         }
 276 }
 277
 278 static LIST_HEAD(undef_hook);
 279 static DEFINE_RAW_SPINLOCK(undef_lock);
 280
 281 void register_undef_hook(struct undef_hook *hook)
 282 {
 283         unsigned long flags;
 284
 285         raw_spin_lock_irqsave(&undef_lock, flags);
 286         list_add(&hook->node, &undef_hook);
 287         raw_spin_unlock_irqrestore(&undef_lock, flags);
 288 }
 289
 290 void unregister_undef_hook(struct undef_hook *hook)
 291 {
 292         unsigned long flags;
 293
 294         raw_spin_lock_irqsave(&undef_lock, flags);
 295         list_del(&hook->node);
 296         raw_spin_unlock_irqrestore(&undef_lock, flags);
 297 }
 298
 299 static int call_undef_hook(struct pt_regs *regs)
 300 {
 301         struct undef_hook *hook;
 302         unsigned long flags;
 303         u32 instr;
 304         int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
 305         void __user *pc = (void __user *)instruction_pointer(regs);
 306
 307         if (!user_mode(regs))
 308                 return 1;
 309
 310         if (compat_thumb_mode(regs)) {
 311                 /* 16-bit Thumb instruction */
 312                 if (get_user(instr, (u16 __user *)pc))
 313                         goto exit;
 314                 instr = le16_to_cpu(instr);
 315                 if (aarch32_insn_is_wide(instr)) {
 316                         u32 instr2;
 317
 318                         if (get_user(instr2, (u16 __user *)(pc + 2)))
 319                                 goto exit;
 320                         instr2 = le16_to_cpu(instr2);
 321                         instr = (instr << 16) | instr2;
 322                 }
 323         } else {
 324                 /* 32-bit ARM instruction */
 325                 if (get_user(instr, (u32 __user *)pc))
 326                         goto exit;
 327                 instr = le32_to_cpu(instr);
 328         }
 329
 330         raw_spin_lock_irqsave(&undef_lock, flags);
 331         list_for_each_entry(hook, &undef_hook, node)
 332                 if ((instr & hook->instr_mask) == hook->instr_val &&
 333                         (regs->pstate & hook->pstate_mask) == hook->pstate_val)
 334                         fn = hook->fn;
 335
 336         raw_spin_unlock_irqrestore(&undef_lock, flags);
 337 exit:
 338         return fn ? fn(regs, instr) : 1;
 339 }
 340
 341 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 342 {
 343         siginfo_t info;
 344         void __user *pc = (void __user *)instruction_pointer(regs);
 345
 346         /* check for AArch32 breakpoint instructions */
 347         if (!aarch32_break_handler(regs))
 348                 return;
 349
 350         if (call_undef_hook(regs) == 0)
 351                 return;
 352
 353         if (unhandled_signal(current, SIGILL) && show_unhandled_signals_ratelimited()) {
 354                 pr_info("%s[%d]: undefined instruction: pc=%p\n",
 355                         current->comm, task_pid_nr(current), pc);
 356                 dump_instr(KERN_INFO, regs);
 357         }
 358
 359         info.si_signo = SIGILL;
 360         info.si_errno = 0;
 361         info.si_code  = ILL_ILLOPC;
 362         info.si_addr  = pc;
 363
 364         arm64_notify_die("Oops - undefined instruction", regs, &info, 0);
 365 }
 366
 367 long compat_arm_syscall(struct pt_regs *regs);
 368
 369 asmlinkage long do_ni_syscall(struct pt_regs *regs)
 370 {
 371 #ifdef CONFIG_COMPAT
 372         long ret;
 373         if (is_compat_task()) {
 374                 ret = compat_arm_syscall(regs);
 375                 if (ret != -ENOSYS)
 376                         return ret;
 377         }
 378 #endif
 379
 380         if (show_unhandled_signals_ratelimited()) {
 381                 pr_info("%s[%d]: syscall %d\n", current->comm,
 382                         task_pid_nr(current), (int)regs->syscallno);
 383                 dump_instr("", regs);
 384                 if (user_mode(regs))
 385                         __show_regs(regs);
 386         }
 387
 388         return sys_ni_syscall();
 389 }
 390
 391 static const char *esr_class_str[] = {
 392         [0 ... ESR_ELx_EC_MAX]          = "UNRECOGNIZED EC",
 393         [ESR_ELx_EC_UNKNOWN]            = "Unknown/Uncategorized",
 394         [ESR_ELx_EC_WFx]                = "WFI/WFE",
 395         [ESR_ELx_EC_CP15_32]            = "CP15 MCR/MRC",
 396         [ESR_ELx_EC_CP15_64]            = "CP15 MCRR/MRRC",
 397         [ESR_ELx_EC_CP14_MR]            = "CP14 MCR/MRC",
 398         [ESR_ELx_EC_CP14_LS]            = "CP14 LDC/STC",
 399         [ESR_ELx_EC_FP_ASIMD]           = "ASIMD",
 400         [ESR_ELx_EC_CP10_ID]            = "CP10 MRC/VMRS",
 401         [ESR_ELx_EC_CP14_64]            = "CP14 MCRR/MRRC",
 402         [ESR_ELx_EC_ILL]                = "PSTATE.IL",
 403         [ESR_ELx_EC_SVC32]              = "SVC (AArch32)",
 404         [ESR_ELx_EC_HVC32]              = "HVC (AArch32)",
 405         [ESR_ELx_EC_SMC32]              = "SMC (AArch32)",
 406         [ESR_ELx_EC_SVC64]              = "SVC (AArch64)",
 407         [ESR_ELx_EC_HVC64]              = "HVC (AArch64)",
 408         [ESR_ELx_EC_SMC64]              = "SMC (AArch64)",
 409         [ESR_ELx_EC_SYS64]              = "MSR/MRS (AArch64)",
 410         [ESR_ELx_EC_IMP_DEF]            = "EL3 IMP DEF",
 411         [ESR_ELx_EC_IABT_LOW]           = "IABT (lower EL)",
 412         [ESR_ELx_EC_IABT_CUR]           = "IABT (current EL)",
 413         [ESR_ELx_EC_PC_ALIGN]           = "PC Alignment",
 414         [ESR_ELx_EC_DABT_LOW]           = "DABT (lower EL)",
 415         [ESR_ELx_EC_DABT_CUR]           = "DABT (current EL)",
 416         [ESR_ELx_EC_SP_ALIGN]           = "SP Alignment",
 417         [ESR_ELx_EC_FP_EXC32]           = "FP (AArch32)",
 418         [ESR_ELx_EC_FP_EXC64]           = "FP (AArch64)",
 419         [ESR_ELx_EC_SERROR]             = "SError",
 420         [ESR_ELx_EC_BREAKPT_LOW]        = "Breakpoint (lower EL)",
 421         [ESR_ELx_EC_BREAKPT_CUR]        = "Breakpoint (current EL)",
 422         [ESR_ELx_EC_SOFTSTP_LOW]        = "Software Step (lower EL)",
 423         [ESR_ELx_EC_SOFTSTP_CUR]        = "Software Step (current EL)",
 424         [ESR_ELx_EC_WATCHPT_LOW]        = "Watchpoint (lower EL)",
 425         [ESR_ELx_EC_WATCHPT_CUR]        = "Watchpoint (current EL)",
 426         [ESR_ELx_EC_BKPT32]             = "BKPT (AArch32)",
 427         [ESR_ELx_EC_VECTOR32]           = "Vector catch (AArch32)",
 428         [ESR_ELx_EC_BRK64]              = "BRK (AArch64)",
 429 };
 430
 431 const char *esr_get_class_string(u32 esr)
 432 {
 433         return esr_class_str[esr >> ESR_ELx_EC_SHIFT];
 434 }
 435
 436 /*
 437  * bad_mode handles the impossible case in the exception vector. This is always
 438  * fatal.
 439  */
 440 asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
 441 {
 442         console_verbose();
 443
 444         pr_crit("Bad mode in %s handler detected, code 0x%08x -- %s\n",
 445                 handler[reason], esr, esr_get_class_string(esr));
 446
 447         die("Oops - bad mode", regs, 0);
 448         local_irq_disable();
 449         panic("bad mode");
 450 }
 451
 452 /*
 453  * bad_el0_sync handles unexpected, but potentially recoverable synchronous
 454  * exceptions taken from EL0. Unlike bad_mode, this returns.
 455  */
 456 asmlinkage void bad_el0_sync(struct pt_regs *regs, int reason, unsigned int esr)
 457 {
 458         siginfo_t info;
 459         void __user *pc = (void __user *)instruction_pointer(regs);
 460         console_verbose();
 461
 462         pr_crit("Bad EL0 synchronous exception detected on CPU%d, code 0x%08x -- %s\n",
 463                 smp_processor_id(), esr, esr_get_class_string(esr));
 464         __show_regs(regs);
 465
 466         info.si_signo = SIGILL;
 467         info.si_errno = 0;
 468         info.si_code  = ILL_ILLOPC;
 469         info.si_addr  = pc;
 470
 471         current->thread.fault_address = 0;
 472         current->thread.fault_code = 0;
 473
 474         force_sig_info(info.si_signo, &info, current);
 475 }
 476
 477 void __pte_error(const char *file, int line, unsigned long val)
 478 {
 479         pr_crit("%s:%d: bad pte %016lx.\n", file, line, val);
 480 }
 481
 482 void __pmd_error(const char *file, int line, unsigned long val)
 483 {
 484         pr_crit("%s:%d: bad pmd %016lx.\n", file, line, val);
 485 }
 486
 487 void __pud_error(const char *file, int line, unsigned long val)
 488 {
 489         pr_crit("%s:%d: bad pud %016lx.\n", file, line, val);
 490 }
 491
 492 void __pgd_error(const char *file, int line, unsigned long val)
 493 {
 494         pr_crit("%s:%d: bad pgd %016lx.\n", file, line, val);
 495 }
 496
 497 /* GENERIC_BUG traps */
 498
 499 int is_valid_bugaddr(unsigned long addr)
 500 {
 501         /*
 502          * bug_handler() only called for BRK #BUG_BRK_IMM.
 503          * So the answer is trivial -- any spurious instances with no
 504          * bug table entry will be rejected by report_bug() and passed
 505          * back to the debug-monitors code and handled as a fatal
 506          * unexpected debug exception.
 507          */
 508         return 1;
 509 }
 510
 511 static int bug_handler(struct pt_regs *regs, unsigned int esr)
 512 {
 513         if (user_mode(regs))
 514                 return DBG_HOOK_ERROR;
 515
 516         switch (report_bug(regs->pc, regs)) {
 517         case BUG_TRAP_TYPE_BUG:
 518                 die("Oops - BUG", regs, 0);
 519                 break;
 520
 521         case BUG_TRAP_TYPE_WARN:
 522                 /* Ideally, report_bug() should backtrace for us... but no. */
 523                 dump_backtrace(regs, NULL);
 524                 break;
 525
 526         default:
 527                 /* unknown/unrecognised bug trap type */
 528                 return DBG_HOOK_ERROR;
 529         }
 530
 531         /* If thread survives, skip over the BUG instruction and continue: */
 532         regs->pc += AARCH64_INSN_SIZE;  /* skip BRK and resume */
 533         return DBG_HOOK_HANDLED;
 534 }
 535
 536 static struct break_hook bug_break_hook = {
 537         .esr_val = 0xf2000000 | BUG_BRK_IMM,
 538         .esr_mask = 0xffffffff,
 539         .fn = bug_handler,
 540 };
 541
 542 /*
 543  * Initial handler for AArch64 BRK exceptions
 544  * This handler only used until debug_traps_init().
 545  */
 546 int __init early_brk64(unsigned long addr, unsigned int esr,
 547                 struct pt_regs *regs)
 548 {
 549         return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
 550 }
 551
 552 /* This registration must happen early, before debug_traps_init(). */
 553 void __init trap_init(void)
 554 {
 555         register_break_hook(&bug_break_hook);
 556 }