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, unsigned long stack)
 107 {
 108         print_ip_sym(where);
 109         if (in_exception_text(where))
 110                 dump_mem("", "Exception stack", stack,
 111                          stack + sizeof(struct pt_regs), false);
 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                 int ret;
 176
 177                 ret = unwind_frame(&frame);
 178                 if (ret < 0)
 179                         break;
 180                 dump_backtrace_entry(where, frame.sp);
 181         }
 182 }
 183
 184 void show_stack(struct task_struct *tsk, unsigned long *sp)
 185 {
 186         dump_backtrace(NULL, tsk);
 187         barrier();
 188 }
 189
 190 #ifdef CONFIG_PREEMPT
 191 #define S_PREEMPT " PREEMPT"
 192 #else
 193 #define S_PREEMPT ""
 194 #endif
 195 #define S_SMP " SMP"
 196
 197 static int __die(const char *str, int err, struct thread_info *thread,
 198                  struct pt_regs *regs)
 199 {
 200         struct task_struct *tsk = thread->task;
 201         static int die_counter;
 202         int ret;
 203
 204         pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
 205                  str, err, ++die_counter);
 206
 207         /* trap and error numbers are mostly meaningless on ARM */
 208         ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV);
 209         if (ret == NOTIFY_STOP)
 210                 return ret;
 211
 212         print_modules();
 213         __show_regs(regs);
 214         pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
 215                  TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
 216
 217         if (!user_mode(regs) || in_interrupt()) {
 218                 dump_mem(KERN_EMERG, "Stack: ", regs->sp,
 219                          THREAD_SIZE + (unsigned long)task_stack_page(tsk),
 220                          compat_user_mode(regs));
 221                 dump_backtrace(regs, tsk);
 222                 dump_instr(KERN_EMERG, regs);
 223         }
 224
 225         return ret;
 226 }
 227
 228 static DEFINE_RAW_SPINLOCK(die_lock);
 229
 230 /*
 231  * This function is protected against re-entrancy.
 232  */
 233 void die(const char *str, struct pt_regs *regs, int err)
 234 {
 235         struct thread_info *thread = current_thread_info();
 236         int ret;
 237
 238         oops_enter();
 239
 240         raw_spin_lock_irq(&die_lock);
 241         console_verbose();
 242         bust_spinlocks(1);
 243         ret = __die(str, err, thread, regs);
 244
 245         if (regs && kexec_should_crash(thread->task))
 246                 crash_kexec(regs);
 247
 248         bust_spinlocks(0);
 249         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 250         raw_spin_unlock_irq(&die_lock);
 251         oops_exit();
 252
 253         if (in_interrupt())
 254                 panic("Fatal exception in interrupt");
 255         if (panic_on_oops)
 256                 panic("Fatal exception");
 257         if (ret != NOTIFY_STOP)
 258                 do_exit(SIGSEGV);
 259 }
 260
 261 void arm64_notify_die(const char *str, struct pt_regs *regs,
 262                       struct siginfo *info, int err)
 263 {
 264         if (user_mode(regs)) {
 265                 current->thread.fault_address = 0;
 266                 current->thread.fault_code = err;
 267                 force_sig_info(info->si_signo, info, current);
 268         } else {
 269                 die(str, regs, err);
 270         }
 271 }
 272
 273 static LIST_HEAD(undef_hook);
 274 static DEFINE_RAW_SPINLOCK(undef_lock);
 275
 276 void register_undef_hook(struct undef_hook *hook)
 277 {
 278         unsigned long flags;
 279
 280         raw_spin_lock_irqsave(&undef_lock, flags);
 281         list_add(&hook->node, &undef_hook);
 282         raw_spin_unlock_irqrestore(&undef_lock, flags);
 283 }
 284
 285 void unregister_undef_hook(struct undef_hook *hook)
 286 {
 287         unsigned long flags;
 288
 289         raw_spin_lock_irqsave(&undef_lock, flags);
 290         list_del(&hook->node);
 291         raw_spin_unlock_irqrestore(&undef_lock, flags);
 292 }
 293
 294 static int call_undef_hook(struct pt_regs *regs)
 295 {
 296         struct undef_hook *hook;
 297         unsigned long flags;
 298         u32 instr;
 299         int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
 300         void __user *pc = (void __user *)instruction_pointer(regs);
 301
 302         if (!user_mode(regs))
 303                 return 1;
 304
 305         if (compat_thumb_mode(regs)) {
 306                 /* 16-bit Thumb instruction */
 307                 if (get_user(instr, (u16 __user *)pc))
 308                         goto exit;
 309                 instr = le16_to_cpu(instr);
 310                 if (aarch32_insn_is_wide(instr)) {
 311                         u32 instr2;
 312
 313                         if (get_user(instr2, (u16 __user *)(pc + 2)))
 314                                 goto exit;
 315                         instr2 = le16_to_cpu(instr2);
 316                         instr = (instr << 16) | instr2;
 317                 }
 318         } else {
 319                 /* 32-bit ARM instruction */
 320                 if (get_user(instr, (u32 __user *)pc))
 321                         goto exit;
 322                 instr = le32_to_cpu(instr);
 323         }
 324
 325         raw_spin_lock_irqsave(&undef_lock, flags);
 326         list_for_each_entry(hook, &undef_hook, node)
 327                 if ((instr & hook->instr_mask) == hook->instr_val &&
 328                         (regs->pstate & hook->pstate_mask) == hook->pstate_val)
 329                         fn = hook->fn;
 330
 331         raw_spin_unlock_irqrestore(&undef_lock, flags);
 332 exit:
 333         return fn ? fn(regs, instr) : 1;
 334 }
 335
 336 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 337 {
 338         siginfo_t info;
 339         void __user *pc = (void __user *)instruction_pointer(regs);
 340
 341         /* check for AArch32 breakpoint instructions */
 342         if (!aarch32_break_handler(regs))
 343                 return;
 344
 345         if (call_undef_hook(regs) == 0)
 346                 return;
 347
 348         if (unhandled_signal(current, SIGILL) && show_unhandled_signals_ratelimited()) {
 349                 pr_info("%s[%d]: undefined instruction: pc=%p\n",
 350                         current->comm, task_pid_nr(current), pc);
 351                 dump_instr(KERN_INFO, regs);
 352         }
 353
 354         info.si_signo = SIGILL;
 355         info.si_errno = 0;
 356         info.si_code  = ILL_ILLOPC;
 357         info.si_addr  = pc;
 358
 359         arm64_notify_die("Oops - undefined instruction", regs, &info, 0);
 360 }
 361
 362 long compat_arm_syscall(struct pt_regs *regs);
 363
 364 asmlinkage long do_ni_syscall(struct pt_regs *regs)
 365 {
 366 #ifdef CONFIG_COMPAT
 367         long ret;
 368         if (is_compat_task()) {
 369                 ret = compat_arm_syscall(regs);
 370                 if (ret != -ENOSYS)
 371                         return ret;
 372         }
 373 #endif
 374
 375         if (show_unhandled_signals_ratelimited()) {
 376                 pr_info("%s[%d]: syscall %d\n", current->comm,
 377                         task_pid_nr(current), (int)regs->syscallno);
 378                 dump_instr("", regs);
 379                 if (user_mode(regs))
 380                         __show_regs(regs);
 381         }
 382
 383         return sys_ni_syscall();
 384 }
 385
 386 static const char *esr_class_str[] = {
 387         [0 ... ESR_ELx_EC_MAX]          = "UNRECOGNIZED EC",
 388         [ESR_ELx_EC_UNKNOWN]            = "Unknown/Uncategorized",
 389         [ESR_ELx_EC_WFx]                = "WFI/WFE",
 390         [ESR_ELx_EC_CP15_32]            = "CP15 MCR/MRC",
 391         [ESR_ELx_EC_CP15_64]            = "CP15 MCRR/MRRC",
 392         [ESR_ELx_EC_CP14_MR]            = "CP14 MCR/MRC",
 393         [ESR_ELx_EC_CP14_LS]            = "CP14 LDC/STC",
 394         [ESR_ELx_EC_FP_ASIMD]           = "ASIMD",
 395         [ESR_ELx_EC_CP10_ID]            = "CP10 MRC/VMRS",
 396         [ESR_ELx_EC_CP14_64]            = "CP14 MCRR/MRRC",
 397         [ESR_ELx_EC_ILL]                = "PSTATE.IL",
 398         [ESR_ELx_EC_SVC32]              = "SVC (AArch32)",
 399         [ESR_ELx_EC_HVC32]              = "HVC (AArch32)",
 400         [ESR_ELx_EC_SMC32]              = "SMC (AArch32)",
 401         [ESR_ELx_EC_SVC64]              = "SVC (AArch64)",
 402         [ESR_ELx_EC_HVC64]              = "HVC (AArch64)",
 403         [ESR_ELx_EC_SMC64]              = "SMC (AArch64)",
 404         [ESR_ELx_EC_SYS64]              = "MSR/MRS (AArch64)",
 405         [ESR_ELx_EC_IMP_DEF]            = "EL3 IMP DEF",
 406         [ESR_ELx_EC_IABT_LOW]           = "IABT (lower EL)",
 407         [ESR_ELx_EC_IABT_CUR]           = "IABT (current EL)",
 408         [ESR_ELx_EC_PC_ALIGN]           = "PC Alignment",
 409         [ESR_ELx_EC_DABT_LOW]           = "DABT (lower EL)",
 410         [ESR_ELx_EC_DABT_CUR]           = "DABT (current EL)",
 411         [ESR_ELx_EC_SP_ALIGN]           = "SP Alignment",
 412         [ESR_ELx_EC_FP_EXC32]           = "FP (AArch32)",
 413         [ESR_ELx_EC_FP_EXC64]           = "FP (AArch64)",
 414         [ESR_ELx_EC_SERROR]             = "SError",
 415         [ESR_ELx_EC_BREAKPT_LOW]        = "Breakpoint (lower EL)",
 416         [ESR_ELx_EC_BREAKPT_CUR]        = "Breakpoint (current EL)",
 417         [ESR_ELx_EC_SOFTSTP_LOW]        = "Software Step (lower EL)",
 418         [ESR_ELx_EC_SOFTSTP_CUR]        = "Software Step (current EL)",
 419         [ESR_ELx_EC_WATCHPT_LOW]        = "Watchpoint (lower EL)",
 420         [ESR_ELx_EC_WATCHPT_CUR]        = "Watchpoint (current EL)",
 421         [ESR_ELx_EC_BKPT32]             = "BKPT (AArch32)",
 422         [ESR_ELx_EC_VECTOR32]           = "Vector catch (AArch32)",
 423         [ESR_ELx_EC_BRK64]              = "BRK (AArch64)",
 424 };
 425
 426 const char *esr_get_class_string(u32 esr)
 427 {
 428         return esr_class_str[esr >> ESR_ELx_EC_SHIFT];
 429 }
 430
 431 /*
 432  * bad_mode handles the impossible case in the exception vector.
 433  */
 434 asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
 435 {
 436         siginfo_t info;
 437         void __user *pc = (void __user *)instruction_pointer(regs);
 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         __show_regs(regs);
 443
 444         info.si_signo = SIGILL;
 445         info.si_errno = 0;
 446         info.si_code  = ILL_ILLOPC;
 447         info.si_addr  = pc;
 448
 449         arm64_notify_die("Oops - bad mode", regs, &info, 0);
 450 }
 451
 452 void __pte_error(const char *file, int line, unsigned long val)
 453 {
 454         pr_crit("%s:%d: bad pte %016lx.\n", file, line, val);
 455 }
 456
 457 void __pmd_error(const char *file, int line, unsigned long val)
 458 {
 459         pr_crit("%s:%d: bad pmd %016lx.\n", file, line, val);
 460 }
 461
 462 void __pud_error(const char *file, int line, unsigned long val)
 463 {
 464         pr_crit("%s:%d: bad pud %016lx.\n", file, line, val);
 465 }
 466
 467 void __pgd_error(const char *file, int line, unsigned long val)
 468 {
 469         pr_crit("%s:%d: bad pgd %016lx.\n", file, line, val);
 470 }
 471
 472 /* GENERIC_BUG traps */
 473
 474 int is_valid_bugaddr(unsigned long addr)
 475 {
 476         /*
 477          * bug_handler() only called for BRK #BUG_BRK_IMM.
 478          * So the answer is trivial -- any spurious instances with no
 479          * bug table entry will be rejected by report_bug() and passed
 480          * back to the debug-monitors code and handled as a fatal
 481          * unexpected debug exception.
 482          */
 483         return 1;
 484 }
 485
 486 static int bug_handler(struct pt_regs *regs, unsigned int esr)
 487 {
 488         if (user_mode(regs))
 489                 return DBG_HOOK_ERROR;
 490
 491         switch (report_bug(regs->pc, regs)) {
 492         case BUG_TRAP_TYPE_BUG:
 493                 die("Oops - BUG", regs, 0);
 494                 break;
 495
 496         case BUG_TRAP_TYPE_WARN:
 497                 /* Ideally, report_bug() should backtrace for us... but no. */
 498                 dump_backtrace(regs, NULL);
 499                 break;
 500
 501         default:
 502                 /* unknown/unrecognised bug trap type */
 503                 return DBG_HOOK_ERROR;
 504         }
 505
 506         /* If thread survives, skip over the BUG instruction and continue: */
 507         regs->pc += AARCH64_INSN_SIZE;  /* skip BRK and resume */
 508         return DBG_HOOK_HANDLED;
 509 }
 510
 511 static struct break_hook bug_break_hook = {
 512         .esr_val = 0xf2000000 | BUG_BRK_IMM,
 513         .esr_mask = 0xffffffff,
 514         .fn = bug_handler,
 515 };
 516
 517 /*
 518  * Initial handler for AArch64 BRK exceptions
 519  * This handler only used until debug_traps_init().
 520  */
 521 int __init early_brk64(unsigned long addr, unsigned int esr,
 522                 struct pt_regs *regs)
 523 {
 524         return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
 525 }
 526
 527 /* This registration must happen early, before debug_traps_init(). */
 528 void __init trap_init(void)
 529 {
 530         register_break_hook(&bug_break_hook);
 531 }