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