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.
  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         unsigned long irq_stack_ptr;
 150         int skip;
 151
 152         /*
 153          * Switching between stacks is valid when tracing current and in
 154          * non-preemptible context.
 155          */
 156         if (tsk == current && !preemptible())
 157                 irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
 158         else
 159                 irq_stack_ptr = 0;
 160
 161         pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
 162
 163         if (!tsk)
 164                 tsk = current;
 165
 166         if (tsk == current) {
 167                 frame.fp = (unsigned long)__builtin_frame_address(0);
 168                 frame.sp = current_stack_pointer;
 169                 frame.pc = (unsigned long)dump_backtrace;
 170         } else {
 171                 /*
 172                  * task blocked in __switch_to
 173                  */
 174                 frame.fp = thread_saved_fp(tsk);
 175                 frame.sp = thread_saved_sp(tsk);
 176                 frame.pc = thread_saved_pc(tsk);
 177         }
 178 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 179         frame.graph = tsk->curr_ret_stack;
 180 #endif
 181
 182         skip = !!regs;
 183         printk("Call trace:\n");
 184         while (1) {
 185                 unsigned long where = frame.pc;
 186                 unsigned long stack;
 187                 int ret;
 188
 189                 /* skip until specified stack frame */
 190                 if (!skip) {
 191                         dump_backtrace_entry(where);
 192                 } else if (frame.fp == regs->regs[29]) {
 193                         skip = 0;
 194                         /*
 195                          * Mostly, this is the case where this function is
 196                          * called in panic/abort. As exception handler's
 197                          * stack frame does not contain the corresponding pc
 198                          * at which an exception has taken place, use regs->pc
 199                          * instead.
 200                          */
 201                         dump_backtrace_entry(regs->pc);
 202                 }
 203                 ret = unwind_frame(tsk, &frame);
 204                 if (ret < 0)
 205                         break;
 206                 stack = frame.sp;
 207                 if (in_exception_text(where)) {
 208                         /*
 209                          * If we switched to the irq_stack before calling this
 210                          * exception handler, then the pt_regs will be on the
 211                          * task stack. The easiest way to tell is if the large
 212                          * pt_regs would overlap with the end of the irq_stack.
 213                          */
 214                         if (stack < irq_stack_ptr &&
 215                             (stack + sizeof(struct pt_regs)) > irq_stack_ptr)
 216                                 stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
 217
 218                         dump_mem("", "Exception stack", stack,
 219                                  stack + sizeof(struct pt_regs), false);
 220                 }
 221         }
 222 }
 223
 224 void show_stack(struct task_struct *tsk, unsigned long *sp)
 225 {
 226         dump_backtrace(NULL, tsk);
 227         barrier();
 228 }
 229
 230 #ifdef CONFIG_PREEMPT
 231 #define S_PREEMPT " PREEMPT"
 232 #else
 233 #define S_PREEMPT ""
 234 #endif
 235 #define S_SMP " SMP"
 236
 237 static int __die(const char *str, int err, struct thread_info *thread,
 238                  struct pt_regs *regs)
 239 {
 240         struct task_struct *tsk = thread->task;
 241         static int die_counter;
 242         int ret;
 243
 244         pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
 245                  str, err, ++die_counter);
 246
 247         /* trap and error numbers are mostly meaningless on ARM */
 248         ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV);
 249         if (ret == NOTIFY_STOP)
 250                 return ret;
 251
 252         print_modules();
 253         __show_regs(regs);
 254         pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
 255                  TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
 256
 257         if (!user_mode(regs) || in_interrupt()) {
 258                 dump_mem(KERN_EMERG, "Stack: ", regs->sp,
 259                          THREAD_SIZE + (unsigned long)task_stack_page(tsk),
 260                          compat_user_mode(regs));
 261                 dump_backtrace(regs, tsk);
 262                 dump_instr(KERN_EMERG, regs);
 263         }
 264
 265         return ret;
 266 }
 267
 268 static DEFINE_RAW_SPINLOCK(die_lock);
 269
 270 /*
 271  * This function is protected against re-entrancy.
 272  */
 273 void die(const char *str, struct pt_regs *regs, int err)
 274 {
 275         struct thread_info *thread = current_thread_info();
 276         int ret;
 277
 278         oops_enter();
 279
 280         raw_spin_lock_irq(&die_lock);
 281         console_verbose();
 282         bust_spinlocks(1);
 283         ret = __die(str, err, thread, regs);
 284
 285         if (regs && kexec_should_crash(thread->task))
 286                 crash_kexec(regs);
 287
 288         bust_spinlocks(0);
 289         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 290         raw_spin_unlock_irq(&die_lock);
 291         oops_exit();
 292
 293         if (in_interrupt())
 294                 panic("Fatal exception in interrupt");
 295         if (panic_on_oops)
 296                 panic("Fatal exception");
 297         if (ret != NOTIFY_STOP)
 298                 do_exit(SIGSEGV);
 299 }
 300
 301 void arm64_notify_die(const char *str, struct pt_regs *regs,
 302                       struct siginfo *info, int err)
 303 {
 304         if (user_mode(regs)) {
 305                 current->thread.fault_address = 0;
 306                 current->thread.fault_code = err;
 307                 force_sig_info(info->si_signo, info, current);
 308         } else {
 309                 die(str, regs, err);
 310         }
 311 }
 312
 313 static LIST_HEAD(undef_hook);
 314 static DEFINE_RAW_SPINLOCK(undef_lock);
 315
 316 void register_undef_hook(struct undef_hook *hook)
 317 {
 318         unsigned long flags;
 319
 320         raw_spin_lock_irqsave(&undef_lock, flags);
 321         list_add(&hook->node, &undef_hook);
 322         raw_spin_unlock_irqrestore(&undef_lock, flags);
 323 }
 324
 325 void unregister_undef_hook(struct undef_hook *hook)
 326 {
 327         unsigned long flags;
 328
 329         raw_spin_lock_irqsave(&undef_lock, flags);
 330         list_del(&hook->node);
 331         raw_spin_unlock_irqrestore(&undef_lock, flags);
 332 }
 333
 334 static int call_undef_hook(struct pt_regs *regs)
 335 {
 336         struct undef_hook *hook;
 337         unsigned long flags;
 338         u32 instr;
 339         int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
 340         void __user *pc = (void __user *)instruction_pointer(regs);
 341
 342         if (!user_mode(regs))
 343                 return 1;
 344
 345         if (compat_thumb_mode(regs)) {
 346                 /* 16-bit Thumb instruction */
 347                 if (get_user(instr, (u16 __user *)pc))
 348                         goto exit;
 349                 instr = le16_to_cpu(instr);
 350                 if (aarch32_insn_is_wide(instr)) {
 351                         u32 instr2;
 352
 353                         if (get_user(instr2, (u16 __user *)(pc + 2)))
 354                                 goto exit;
 355                         instr2 = le16_to_cpu(instr2);
 356                         instr = (instr << 16) | instr2;
 357                 }
 358         } else {
 359                 /* 32-bit ARM instruction */
 360                 if (get_user(instr, (u32 __user *)pc))
 361                         goto exit;
 362                 instr = le32_to_cpu(instr);
 363         }
 364
 365         raw_spin_lock_irqsave(&undef_lock, flags);
 366         list_for_each_entry(hook, &undef_hook, node)
 367                 if ((instr & hook->instr_mask) == hook->instr_val &&
 368                         (regs->pstate & hook->pstate_mask) == hook->pstate_val)
 369                         fn = hook->fn;
 370
 371         raw_spin_unlock_irqrestore(&undef_lock, flags);
 372 exit:
 373         return fn ? fn(regs, instr) : 1;
 374 }
 375
 376 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 377 {
 378         siginfo_t info;
 379         void __user *pc = (void __user *)instruction_pointer(regs);
 380
 381         /* check for AArch32 breakpoint instructions */
 382         if (!aarch32_break_handler(regs))
 383                 return;
 384
 385         if (call_undef_hook(regs) == 0)
 386                 return;
 387
 388         if (unhandled_signal(current, SIGILL) && show_unhandled_signals_ratelimited()) {
 389                 pr_info("%s[%d]: undefined instruction: pc=%p\n",
 390                         current->comm, task_pid_nr(current), pc);
 391                 dump_instr(KERN_INFO, regs);
 392         }
 393
 394         info.si_signo = SIGILL;
 395         info.si_errno = 0;
 396         info.si_code  = ILL_ILLOPC;
 397         info.si_addr  = pc;
 398
 399         arm64_notify_die("Oops - undefined instruction", regs, &info, 0);
 400 }
 401
 402 long compat_arm_syscall(struct pt_regs *regs);
 403
 404 asmlinkage long do_ni_syscall(struct pt_regs *regs)
 405 {
 406 #ifdef CONFIG_COMPAT
 407         long ret;
 408         if (is_compat_task()) {
 409                 ret = compat_arm_syscall(regs);
 410                 if (ret != -ENOSYS)
 411                         return ret;
 412         }
 413 #endif
 414
 415         if (show_unhandled_signals_ratelimited()) {
 416                 pr_info("%s[%d]: syscall %d\n", current->comm,
 417                         task_pid_nr(current), (int)regs->syscallno);
 418                 dump_instr("", regs);
 419                 if (user_mode(regs))
 420                         __show_regs(regs);
 421         }
 422
 423         return sys_ni_syscall();
 424 }
 425
 426 static const char *esr_class_str[] = {
 427         [0 ... ESR_ELx_EC_MAX]          = "UNRECOGNIZED EC",
 428         [ESR_ELx_EC_UNKNOWN]            = "Unknown/Uncategorized",
 429         [ESR_ELx_EC_WFx]                = "WFI/WFE",
 430         [ESR_ELx_EC_CP15_32]            = "CP15 MCR/MRC",
 431         [ESR_ELx_EC_CP15_64]            = "CP15 MCRR/MRRC",
 432         [ESR_ELx_EC_CP14_MR]            = "CP14 MCR/MRC",
 433         [ESR_ELx_EC_CP14_LS]            = "CP14 LDC/STC",
 434         [ESR_ELx_EC_FP_ASIMD]           = "ASIMD",
 435         [ESR_ELx_EC_CP10_ID]            = "CP10 MRC/VMRS",
 436         [ESR_ELx_EC_CP14_64]            = "CP14 MCRR/MRRC",
 437         [ESR_ELx_EC_ILL]                = "PSTATE.IL",
 438         [ESR_ELx_EC_SVC32]              = "SVC (AArch32)",
 439         [ESR_ELx_EC_HVC32]              = "HVC (AArch32)",
 440         [ESR_ELx_EC_SMC32]              = "SMC (AArch32)",
 441         [ESR_ELx_EC_SVC64]              = "SVC (AArch64)",
 442         [ESR_ELx_EC_HVC64]              = "HVC (AArch64)",
 443         [ESR_ELx_EC_SMC64]              = "SMC (AArch64)",
 444         [ESR_ELx_EC_SYS64]              = "MSR/MRS (AArch64)",
 445         [ESR_ELx_EC_IMP_DEF]            = "EL3 IMP DEF",
 446         [ESR_ELx_EC_IABT_LOW]           = "IABT (lower EL)",
 447         [ESR_ELx_EC_IABT_CUR]           = "IABT (current EL)",
 448         [ESR_ELx_EC_PC_ALIGN]           = "PC Alignment",
 449         [ESR_ELx_EC_DABT_LOW]           = "DABT (lower EL)",
 450         [ESR_ELx_EC_DABT_CUR]           = "DABT (current EL)",
 451         [ESR_ELx_EC_SP_ALIGN]           = "SP Alignment",
 452         [ESR_ELx_EC_FP_EXC32]           = "FP (AArch32)",
 453         [ESR_ELx_EC_FP_EXC64]           = "FP (AArch64)",
 454         [ESR_ELx_EC_SERROR]             = "SError",
 455         [ESR_ELx_EC_BREAKPT_LOW]        = "Breakpoint (lower EL)",
 456         [ESR_ELx_EC_BREAKPT_CUR]        = "Breakpoint (current EL)",
 457         [ESR_ELx_EC_SOFTSTP_LOW]        = "Software Step (lower EL)",
 458         [ESR_ELx_EC_SOFTSTP_CUR]        = "Software Step (current EL)",
 459         [ESR_ELx_EC_WATCHPT_LOW]        = "Watchpoint (lower EL)",
 460         [ESR_ELx_EC_WATCHPT_CUR]        = "Watchpoint (current EL)",
 461         [ESR_ELx_EC_BKPT32]             = "BKPT (AArch32)",
 462         [ESR_ELx_EC_VECTOR32]           = "Vector catch (AArch32)",
 463         [ESR_ELx_EC_BRK64]              = "BRK (AArch64)",
 464 };
 465
 466 const char *esr_get_class_string(u32 esr)
 467 {
 468         return esr_class_str[esr >> ESR_ELx_EC_SHIFT];
 469 }
 470
 471 /*
 472  * bad_mode handles the impossible case in the exception vector.
 473  */
 474 asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
 475 {
 476         siginfo_t info;
 477         void __user *pc = (void __user *)instruction_pointer(regs);
 478         console_verbose();
 479
 480         pr_crit("Bad mode in %s handler detected on CPU%d, code 0x%08x -- %s\n",
 481                 handler[reason], smp_processor_id(), esr,
 482                 esr_get_class_string(esr));
 483         __show_regs(regs);
 484
 485         info.si_signo = SIGILL;
 486         info.si_errno = 0;
 487         info.si_code  = ILL_ILLOPC;
 488         info.si_addr  = pc;
 489
 490         arm64_notify_die("Oops - bad mode", regs, &info, 0);
 491 }
 492
 493 void __pte_error(const char *file, int line, unsigned long val)
 494 {
 495         pr_err("%s:%d: bad pte %016lx.\n", file, line, val);
 496 }
 497
 498 void __pmd_error(const char *file, int line, unsigned long val)
 499 {
 500         pr_err("%s:%d: bad pmd %016lx.\n", file, line, val);
 501 }
 502
 503 void __pud_error(const char *file, int line, unsigned long val)
 504 {
 505         pr_err("%s:%d: bad pud %016lx.\n", file, line, val);
 506 }
 507
 508 void __pgd_error(const char *file, int line, unsigned long val)
 509 {
 510         pr_err("%s:%d: bad pgd %016lx.\n", file, line, val);
 511 }
 512
 513 /* GENERIC_BUG traps */
 514
 515 int is_valid_bugaddr(unsigned long addr)
 516 {
 517         /*
 518          * bug_handler() only called for BRK #BUG_BRK_IMM.
 519          * So the answer is trivial -- any spurious instances with no
 520          * bug table entry will be rejected by report_bug() and passed
 521          * back to the debug-monitors code and handled as a fatal
 522          * unexpected debug exception.
 523          */
 524         return 1;
 525 }
 526
 527 static int bug_handler(struct pt_regs *regs, unsigned int esr)
 528 {
 529         if (user_mode(regs))
 530                 return DBG_HOOK_ERROR;
 531
 532         switch (report_bug(regs->pc, regs)) {
 533         case BUG_TRAP_TYPE_BUG:
 534                 die("Oops - BUG", regs, 0);
 535                 break;
 536
 537         case BUG_TRAP_TYPE_WARN:
 538                 /* Ideally, report_bug() should backtrace for us... but no. */
 539                 dump_backtrace(regs, NULL);
 540                 break;
 541
 542         default:
 543                 /* unknown/unrecognised bug trap type */
 544                 return DBG_HOOK_ERROR;
 545         }
 546
 547         /* If thread survives, skip over the BUG instruction and continue: */
 548         regs->pc += AARCH64_INSN_SIZE;  /* skip BRK and resume */
 549         return DBG_HOOK_HANDLED;
 550 }
 551
 552 static struct break_hook bug_break_hook = {
 553         .esr_val = 0xf2000000 | BUG_BRK_IMM,
 554         .esr_mask = 0xffffffff,
 555         .fn = bug_handler,
 556 };
 557
 558 /*
 559  * Initial handler for AArch64 BRK exceptions
 560  * This handler only used until debug_traps_init().
 561  */
 562 int __init early_brk64(unsigned long addr, unsigned int esr,
 563                 struct pt_regs *regs)
 564 {
 565         return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
 566 }
 567
 568 /* This registration must happen early, before debug_traps_init(). */
 569 void __init trap_init(void)
 570 {
 571         register_break_hook(&bug_break_hook);
 572 }