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         unsigned long irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
 150         int skip;
 151
 152         pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
 153
 154         if (!tsk)
 155                 tsk = current;
 156
 157         if (tsk == current) {
 158                 frame.fp = (unsigned long)__builtin_frame_address(0);
 159                 frame.sp = current_stack_pointer;
 160                 frame.pc = (unsigned long)dump_backtrace;
 161         } else {
 162                 /*
 163                  * task blocked in __switch_to
 164                  */
 165                 frame.fp = thread_saved_fp(tsk);
 166                 frame.sp = thread_saved_sp(tsk);
 167                 frame.pc = thread_saved_pc(tsk);
 168         }
 169 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 170         frame.graph = tsk->curr_ret_stack;
 171 #endif
 172
 173         skip = !!regs;
 174         printk("Call trace:\n");
 175         while (1) {
 176                 unsigned long where = frame.pc;
 177                 unsigned long stack;
 178                 int ret;
 179
 180                 /* skip until specified stack frame */
 181                 if (!skip) {
 182                         dump_backtrace_entry(where);
 183                 } else if (frame.fp == regs->regs[29]) {
 184                         skip = 0;
 185                         /*
 186                          * Mostly, this is the case where this function is
 187                          * called in panic/abort. As exception handler's
 188                          * stack frame does not contain the corresponding pc
 189                          * at which an exception has taken place, use regs->pc
 190                          * instead.
 191                          */
 192                         dump_backtrace_entry(regs->pc);
 193                 }
 194                 ret = unwind_frame(tsk, &frame);
 195                 if (ret < 0)
 196                         break;
 197                 stack = frame.sp;
 198                 if (in_exception_text(where)) {
 199                         /*
 200                          * If we switched to the irq_stack before calling this
 201                          * exception handler, then the pt_regs will be on the
 202                          * task stack. The easiest way to tell is if the large
 203                          * pt_regs would overlap with the end of the irq_stack.
 204                          */
 205                         if (stack < irq_stack_ptr &&
 206                             (stack + sizeof(struct pt_regs)) > irq_stack_ptr)
 207                                 stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
 208
 209                         dump_mem("", "Exception stack", stack,
 210                                  stack + sizeof(struct pt_regs), false);
 211                 }
 212         }
 213 }
 214
 215 void show_stack(struct task_struct *tsk, unsigned long *sp)
 216 {
 217         dump_backtrace(NULL, tsk);
 218         barrier();
 219 }
 220
 221 #ifdef CONFIG_PREEMPT
 222 #define S_PREEMPT " PREEMPT"
 223 #else
 224 #define S_PREEMPT ""
 225 #endif
 226 #define S_SMP " SMP"
 227
 228 static int __die(const char *str, int err, struct thread_info *thread,
 229                  struct pt_regs *regs)
 230 {
 231         struct task_struct *tsk = thread->task;
 232         static int die_counter;
 233         int ret;
 234
 235         pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
 236                  str, err, ++die_counter);
 237
 238         /* trap and error numbers are mostly meaningless on ARM */
 239         ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV);
 240         if (ret == NOTIFY_STOP)
 241                 return ret;
 242
 243         print_modules();
 244         __show_regs(regs);
 245         pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
 246                  TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
 247
 248         if (!user_mode(regs) || in_interrupt()) {
 249                 dump_mem(KERN_EMERG, "Stack: ", regs->sp,
 250                          THREAD_SIZE + (unsigned long)task_stack_page(tsk),
 251                          compat_user_mode(regs));
 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 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 368 {
 369         siginfo_t info;
 370         void __user *pc = (void __user *)instruction_pointer(regs);
 371
 372         /* check for AArch32 breakpoint instructions */
 373         if (!aarch32_break_handler(regs))
 374                 return;
 375
 376         if (call_undef_hook(regs) == 0)
 377                 return;
 378
 379         if (unhandled_signal(current, SIGILL) && show_unhandled_signals_ratelimited()) {
 380                 pr_info("%s[%d]: undefined instruction: pc=%p\n",
 381                         current->comm, task_pid_nr(current), pc);
 382                 dump_instr(KERN_INFO, regs);
 383         }
 384
 385         info.si_signo = SIGILL;
 386         info.si_errno = 0;
 387         info.si_code  = ILL_ILLOPC;
 388         info.si_addr  = pc;
 389
 390         arm64_notify_die("Oops - undefined instruction", regs, &info, 0);
 391 }
 392
 393 long compat_arm_syscall(struct pt_regs *regs);
 394
 395 asmlinkage long do_ni_syscall(struct pt_regs *regs)
 396 {
 397 #ifdef CONFIG_COMPAT
 398         long ret;
 399         if (is_compat_task()) {
 400                 ret = compat_arm_syscall(regs);
 401                 if (ret != -ENOSYS)
 402                         return ret;
 403         }
 404 #endif
 405
 406         if (show_unhandled_signals_ratelimited()) {
 407                 pr_info("%s[%d]: syscall %d\n", current->comm,
 408                         task_pid_nr(current), (int)regs->syscallno);
 409                 dump_instr("", regs);
 410                 if (user_mode(regs))
 411                         __show_regs(regs);
 412         }
 413
 414         return sys_ni_syscall();
 415 }
 416
 417 static const char *esr_class_str[] = {
 418         [0 ... ESR_ELx_EC_MAX]          = "UNRECOGNIZED EC",
 419         [ESR_ELx_EC_UNKNOWN]            = "Unknown/Uncategorized",
 420         [ESR_ELx_EC_WFx]                = "WFI/WFE",
 421         [ESR_ELx_EC_CP15_32]            = "CP15 MCR/MRC",
 422         [ESR_ELx_EC_CP15_64]            = "CP15 MCRR/MRRC",
 423         [ESR_ELx_EC_CP14_MR]            = "CP14 MCR/MRC",
 424         [ESR_ELx_EC_CP14_LS]            = "CP14 LDC/STC",
 425         [ESR_ELx_EC_FP_ASIMD]           = "ASIMD",
 426         [ESR_ELx_EC_CP10_ID]            = "CP10 MRC/VMRS",
 427         [ESR_ELx_EC_CP14_64]            = "CP14 MCRR/MRRC",
 428         [ESR_ELx_EC_ILL]                = "PSTATE.IL",
 429         [ESR_ELx_EC_SVC32]              = "SVC (AArch32)",
 430         [ESR_ELx_EC_HVC32]              = "HVC (AArch32)",
 431         [ESR_ELx_EC_SMC32]              = "SMC (AArch32)",
 432         [ESR_ELx_EC_SVC64]              = "SVC (AArch64)",
 433         [ESR_ELx_EC_HVC64]              = "HVC (AArch64)",
 434         [ESR_ELx_EC_SMC64]              = "SMC (AArch64)",
 435         [ESR_ELx_EC_SYS64]              = "MSR/MRS (AArch64)",
 436         [ESR_ELx_EC_IMP_DEF]            = "EL3 IMP DEF",
 437         [ESR_ELx_EC_IABT_LOW]           = "IABT (lower EL)",
 438         [ESR_ELx_EC_IABT_CUR]           = "IABT (current EL)",
 439         [ESR_ELx_EC_PC_ALIGN]           = "PC Alignment",
 440         [ESR_ELx_EC_DABT_LOW]           = "DABT (lower EL)",
 441         [ESR_ELx_EC_DABT_CUR]           = "DABT (current EL)",
 442         [ESR_ELx_EC_SP_ALIGN]           = "SP Alignment",
 443         [ESR_ELx_EC_FP_EXC32]           = "FP (AArch32)",
 444         [ESR_ELx_EC_FP_EXC64]           = "FP (AArch64)",
 445         [ESR_ELx_EC_SERROR]             = "SError",
 446         [ESR_ELx_EC_BREAKPT_LOW]        = "Breakpoint (lower EL)",
 447         [ESR_ELx_EC_BREAKPT_CUR]        = "Breakpoint (current EL)",
 448         [ESR_ELx_EC_SOFTSTP_LOW]        = "Software Step (lower EL)",
 449         [ESR_ELx_EC_SOFTSTP_CUR]        = "Software Step (current EL)",
 450         [ESR_ELx_EC_WATCHPT_LOW]        = "Watchpoint (lower EL)",
 451         [ESR_ELx_EC_WATCHPT_CUR]        = "Watchpoint (current EL)",
 452         [ESR_ELx_EC_BKPT32]             = "BKPT (AArch32)",
 453         [ESR_ELx_EC_VECTOR32]           = "Vector catch (AArch32)",
 454         [ESR_ELx_EC_BRK64]              = "BRK (AArch64)",
 455 };
 456
 457 const char *esr_get_class_string(u32 esr)
 458 {
 459         return esr_class_str[esr >> ESR_ELx_EC_SHIFT];
 460 }
 461
 462 /*
 463  * bad_mode handles the impossible case in the exception vector.
 464  */
 465 asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
 466 {
 467         siginfo_t info;
 468         void __user *pc = (void __user *)instruction_pointer(regs);
 469         console_verbose();
 470
 471         pr_crit("Bad mode in %s handler detected, code 0x%08x -- %s\n",
 472                 handler[reason], esr, esr_get_class_string(esr));
 473         __show_regs(regs);
 474
 475         info.si_signo = SIGILL;
 476         info.si_errno = 0;
 477         info.si_code  = ILL_ILLOPC;
 478         info.si_addr  = pc;
 479
 480         arm64_notify_die("Oops - bad mode", regs, &info, 0);
 481 }
 482
 483 void __pte_error(const char *file, int line, unsigned long val)
 484 {
 485         pr_err("%s:%d: bad pte %016lx.\n", file, line, val);
 486 }
 487
 488 void __pmd_error(const char *file, int line, unsigned long val)
 489 {
 490         pr_err("%s:%d: bad pmd %016lx.\n", file, line, val);
 491 }
 492
 493 void __pud_error(const char *file, int line, unsigned long val)
 494 {
 495         pr_err("%s:%d: bad pud %016lx.\n", file, line, val);
 496 }
 497
 498 void __pgd_error(const char *file, int line, unsigned long val)
 499 {
 500         pr_err("%s:%d: bad pgd %016lx.\n", file, line, val);
 501 }
 502
 503 /* GENERIC_BUG traps */
 504
 505 int is_valid_bugaddr(unsigned long addr)
 506 {
 507         /*
 508          * bug_handler() only called for BRK #BUG_BRK_IMM.
 509          * So the answer is trivial -- any spurious instances with no
 510          * bug table entry will be rejected by report_bug() and passed
 511          * back to the debug-monitors code and handled as a fatal
 512          * unexpected debug exception.
 513          */
 514         return 1;
 515 }
 516
 517 static int bug_handler(struct pt_regs *regs, unsigned int esr)
 518 {
 519         if (user_mode(regs))
 520                 return DBG_HOOK_ERROR;
 521
 522         switch (report_bug(regs->pc, regs)) {
 523         case BUG_TRAP_TYPE_BUG:
 524                 die("Oops - BUG", regs, 0);
 525                 break;
 526
 527         case BUG_TRAP_TYPE_WARN:
 528                 /* Ideally, report_bug() should backtrace for us... but no. */
 529                 dump_backtrace(regs, NULL);
 530                 break;
 531
 532         default:
 533                 /* unknown/unrecognised bug trap type */
 534                 return DBG_HOOK_ERROR;
 535         }
 536
 537         /* If thread survives, skip over the BUG instruction and continue: */
 538         regs->pc += AARCH64_INSN_SIZE;  /* skip BRK and resume */
 539         return DBG_HOOK_HANDLED;
 540 }
 541
 542 static struct break_hook bug_break_hook = {
 543         .esr_val = 0xf2000000 | BUG_BRK_IMM,
 544         .esr_mask = 0xffffffff,
 545         .fn = bug_handler,
 546 };
 547
 548 /*
 549  * Initial handler for AArch64 BRK exceptions
 550  * This handler only used until debug_traps_init().
 551  */
 552 int __init early_brk64(unsigned long addr, unsigned int esr,
 553                 struct pt_regs *regs)
 554 {
 555         return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
 556 }
 557
 558 /* This registration must happen early, before debug_traps_init(). */
 559 void __init trap_init(void)
 560 {
 561         register_break_hook(&bug_break_hook);
 562 }