arch/arm/kernel/traps.c

   1 /*
   2  *  linux/arch/arm/kernel/traps.c
   3  *
   4  *  Copyright (C) 1995-2009 Russell King
   5  *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
   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  *  'traps.c' handles hardware exceptions after we have saved some state in
  12  *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
  13  *  kill the offending process.
  14  */
  15 #include <linux/signal.h>
  16 #include <linux/personality.h>
  17 #include <linux/kallsyms.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/hardirq.h>
  21 #include <linux/kdebug.h>
  22 #include <linux/module.h>
  23 #include <linux/kexec.h>
  24 #include <linux/bug.h>
  25 #include <linux/delay.h>
  26 #include <linux/init.h>
  27 #include <linux/sched/signal.h>
  28 #include <linux/sched/debug.h>
  29 #include <linux/sched/task_stack.h>
  30 #include <linux/irq.h>
  31
  32 #include <linux/atomic.h>
  33 #include <asm/cacheflush.h>
  34 #include <asm/exception.h>
  35 #include <asm/unistd.h>
  36 #include <asm/traps.h>
  37 #include <asm/ptrace.h>
  38 #include <asm/unwind.h>
  39 #include <asm/tls.h>
  40 #include <asm/system_misc.h>
  41 #include <asm/opcodes.h>
  42
  43
  44 static const char *handler[]= {
  45         "prefetch abort",
  46         "data abort",
  47         "address exception",
  48         "interrupt",
  49         "undefined instruction",
  50 };
  51
  52 void *vectors_page;
  53
  54 #ifdef CONFIG_DEBUG_USER
  55 unsigned int user_debug;
  56
  57 static int __init user_debug_setup(char *str)
  58 {
  59         get_option(&str, &user_debug);
  60         return 1;
  61 }
  62 __setup("user_debug=", user_debug_setup);
  63 #endif
  64
  65 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
  66
  67 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
  68 {
  69 #ifdef CONFIG_KALLSYMS
  70         printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
  71 #else
  72         printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
  73 #endif
  74
  75         if (in_entry_text(from))
  76                 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
  77 }
  78
  79 void dump_backtrace_stm(u32 *stack, u32 instruction)
  80 {
  81         char str[80], *p;
  82         unsigned int x;
  83         int reg;
  84
  85         for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
  86                 if (instruction & BIT(reg)) {
  87                         p += sprintf(p, " r%d:%08x", reg, *stack--);
  88                         if (++x == 6) {
  89                                 x = 0;
  90                                 p = str;
  91                                 printk("%s\n", str);
  92                         }
  93                 }
  94         }
  95         if (p != str)
  96                 printk("%s\n", str);
  97 }
  98
  99 #ifndef CONFIG_ARM_UNWIND
 100 /*
 101  * Stack pointers should always be within the kernels view of
 102  * physical memory.  If it is not there, then we can't dump
 103  * out any information relating to the stack.
 104  */
 105 static int verify_stack(unsigned long sp)
 106 {
 107         if (sp < PAGE_OFFSET ||
 108             (sp > (unsigned long)high_memory && high_memory != NULL))
 109                 return -EFAULT;
 110
 111         return 0;
 112 }
 113 #endif
 114
 115 /*
 116  * Dump out the contents of some memory nicely...
 117  */
 118 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
 119                      unsigned long top)
 120 {
 121         unsigned long first;
 122         mm_segment_t fs;
 123         int i;
 124
 125         /*
 126          * We need to switch to kernel mode so that we can use __get_user
 127          * to safely read from kernel space.  Note that we now dump the
 128          * code first, just in case the backtrace kills us.
 129          */
 130         fs = get_fs();
 131         set_fs(KERNEL_DS);
 132
 133         printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
 134
 135         for (first = bottom & ~31; first < top; first += 32) {
 136                 unsigned long p;
 137                 char str[sizeof(" 12345678") * 8 + 1];
 138
 139                 memset(str, ' ', sizeof(str));
 140                 str[sizeof(str) - 1] = '\0';
 141
 142                 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
 143                         if (p >= bottom && p < top) {
 144                                 unsigned long val;
 145                                 if (__get_user(val, (unsigned long *)p) == 0)
 146                                         sprintf(str + i * 9, " %08lx", val);
 147                                 else
 148                                         sprintf(str + i * 9, " ????????");
 149                         }
 150                 }
 151                 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
 152         }
 153
 154         set_fs(fs);
 155 }
 156
 157 static void __dump_instr(const char *lvl, struct pt_regs *regs)
 158 {
 159         unsigned long addr = instruction_pointer(regs);
 160         const int thumb = thumb_mode(regs);
 161         const int width = thumb ? 4 : 8;
 162         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 163         int i;
 164
 165         /*
 166          * Note that we now dump the code first, just in case the backtrace
 167          * kills us.
 168          */
 169
 170         for (i = -4; i < 1 + !!thumb; i++) {
 171                 unsigned int val, bad;
 172
 173                 if (thumb)
 174                         bad = get_user(val, &((u16 *)addr)[i]);
 175                 else
 176                         bad = get_user(val, &((u32 *)addr)[i]);
 177
 178                 if (!bad)
 179                         p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
 180                                         width, val);
 181                 else {
 182                         p += sprintf(p, "bad PC value");
 183                         break;
 184                 }
 185         }
 186         printk("%sCode: %s\n", lvl, str);
 187 }
 188
 189 static void dump_instr(const char *lvl, struct pt_regs *regs)
 190 {
 191         mm_segment_t fs;
 192
 193         if (!user_mode(regs)) {
 194                 fs = get_fs();
 195                 set_fs(KERNEL_DS);
 196                 __dump_instr(lvl, regs);
 197                 set_fs(fs);
 198         } else {
 199                 __dump_instr(lvl, regs);
 200         }
 201 }
 202
 203 #ifdef CONFIG_ARM_UNWIND
 204 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 205 {
 206         unwind_backtrace(regs, tsk);
 207 }
 208 #else
 209 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 210 {
 211         unsigned int fp, mode;
 212         int ok = 1;
 213
 214         printk("Backtrace: ");
 215
 216         if (!tsk)
 217                 tsk = current;
 218
 219         if (regs) {
 220                 fp = frame_pointer(regs);
 221                 mode = processor_mode(regs);
 222         } else if (tsk != current) {
 223                 fp = thread_saved_fp(tsk);
 224                 mode = 0x10;
 225         } else {
 226                 asm("mov %0, fp" : "=r" (fp) : : "cc");
 227                 mode = 0x10;
 228         }
 229
 230         if (!fp) {
 231                 pr_cont("no frame pointer");
 232                 ok = 0;
 233         } else if (verify_stack(fp)) {
 234                 pr_cont("invalid frame pointer 0x%08x", fp);
 235                 ok = 0;
 236         } else if (fp < (unsigned long)end_of_stack(tsk))
 237                 pr_cont("frame pointer underflow");
 238         pr_cont("\n");
 239
 240         if (ok)
 241                 c_backtrace(fp, mode);
 242 }
 243 #endif
 244
 245 void show_stack(struct task_struct *tsk, unsigned long *sp)
 246 {
 247         dump_backtrace(NULL, tsk);
 248         barrier();
 249 }
 250
 251 #ifdef CONFIG_PREEMPT
 252 #define S_PREEMPT " PREEMPT"
 253 #else
 254 #define S_PREEMPT ""
 255 #endif
 256 #ifdef CONFIG_SMP
 257 #define S_SMP " SMP"
 258 #else
 259 #define S_SMP ""
 260 #endif
 261 #ifdef CONFIG_THUMB2_KERNEL
 262 #define S_ISA " THUMB2"
 263 #else
 264 #define S_ISA " ARM"
 265 #endif
 266
 267 static int __die(const char *str, int err, struct pt_regs *regs)
 268 {
 269         struct task_struct *tsk = current;
 270         static int die_counter;
 271         int ret;
 272
 273         pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
 274                  str, err, ++die_counter);
 275
 276         /* trap and error numbers are mostly meaningless on ARM */
 277         ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
 278         if (ret == NOTIFY_STOP)
 279                 return 1;
 280
 281         print_modules();
 282         __show_regs(regs);
 283         pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
 284                  TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
 285
 286         if (!user_mode(regs) || in_interrupt()) {
 287                 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
 288                          THREAD_SIZE + (unsigned long)task_stack_page(tsk));
 289                 dump_backtrace(regs, tsk);
 290                 dump_instr(KERN_EMERG, regs);
 291         }
 292
 293         return 0;
 294 }
 295
 296 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
 297 static int die_owner = -1;
 298 static unsigned int die_nest_count;
 299
 300 static unsigned long oops_begin(void)
 301 {
 302         int cpu;
 303         unsigned long flags;
 304
 305         oops_enter();
 306
 307         /* racy, but better than risking deadlock. */
 308         raw_local_irq_save(flags);
 309         cpu = smp_processor_id();
 310         if (!arch_spin_trylock(&die_lock)) {
 311                 if (cpu == die_owner)
 312                         /* nested oops. should stop eventually */;
 313                 else
 314                         arch_spin_lock(&die_lock);
 315         }
 316         die_nest_count++;
 317         die_owner = cpu;
 318         console_verbose();
 319         bust_spinlocks(1);
 320         return flags;
 321 }
 322
 323 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
 324 {
 325         if (regs && kexec_should_crash(current))
 326                 crash_kexec(regs);
 327
 328         bust_spinlocks(0);
 329         die_owner = -1;
 330         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 331         die_nest_count--;
 332         if (!die_nest_count)
 333                 /* Nest count reaches zero, release the lock. */
 334                 arch_spin_unlock(&die_lock);
 335         raw_local_irq_restore(flags);
 336         oops_exit();
 337
 338         if (in_interrupt())
 339                 panic("Fatal exception in interrupt");
 340         if (panic_on_oops)
 341                 panic("Fatal exception");
 342         if (signr)
 343                 do_exit(signr);
 344 }
 345
 346 /*
 347  * This function is protected against re-entrancy.
 348  */
 349 void die(const char *str, struct pt_regs *regs, int err)
 350 {
 351         enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
 352         unsigned long flags = oops_begin();
 353         int sig = SIGSEGV;
 354
 355         if (!user_mode(regs))
 356                 bug_type = report_bug(regs->ARM_pc, regs);
 357         if (bug_type != BUG_TRAP_TYPE_NONE)
 358                 str = "Oops - BUG";
 359
 360         if (__die(str, err, regs))
 361                 sig = 0;
 362
 363         oops_end(flags, regs, sig);
 364 }
 365
 366 void arm_notify_die(const char *str, struct pt_regs *regs,
 367                 struct siginfo *info, unsigned long err, unsigned long trap)
 368 {
 369         if (user_mode(regs)) {
 370                 current->thread.error_code = err;
 371                 current->thread.trap_no = trap;
 372
 373                 force_sig_info(info->si_signo, info, current);
 374         } else {
 375                 die(str, regs, err);
 376         }
 377 }
 378
 379 #ifdef CONFIG_GENERIC_BUG
 380
 381 int is_valid_bugaddr(unsigned long pc)
 382 {
 383 #ifdef CONFIG_THUMB2_KERNEL
 384         u16 bkpt;
 385         u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
 386 #else
 387         u32 bkpt;
 388         u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
 389 #endif
 390
 391         if (probe_kernel_address((unsigned *)pc, bkpt))
 392                 return 0;
 393
 394         return bkpt == insn;
 395 }
 396
 397 #endif
 398
 399 static LIST_HEAD(undef_hook);
 400 static DEFINE_RAW_SPINLOCK(undef_lock);
 401
 402 void register_undef_hook(struct undef_hook *hook)
 403 {
 404         unsigned long flags;
 405
 406         raw_spin_lock_irqsave(&undef_lock, flags);
 407         list_add(&hook->node, &undef_hook);
 408         raw_spin_unlock_irqrestore(&undef_lock, flags);
 409 }
 410
 411 void unregister_undef_hook(struct undef_hook *hook)
 412 {
 413         unsigned long flags;
 414
 415         raw_spin_lock_irqsave(&undef_lock, flags);
 416         list_del(&hook->node);
 417         raw_spin_unlock_irqrestore(&undef_lock, flags);
 418 }
 419
 420 static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
 421 {
 422         struct undef_hook *hook;
 423         unsigned long flags;
 424         int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
 425
 426         raw_spin_lock_irqsave(&undef_lock, flags);
 427         list_for_each_entry(hook, &undef_hook, node)
 428                 if ((instr & hook->instr_mask) == hook->instr_val &&
 429                     (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
 430                         fn = hook->fn;
 431         raw_spin_unlock_irqrestore(&undef_lock, flags);
 432
 433         return fn ? fn(regs, instr) : 1;
 434 }
 435
 436 asmlinkage void do_undefinstr(struct pt_regs *regs)
 437 {
 438         unsigned int instr;
 439         siginfo_t info;
 440         void __user *pc;
 441
 442         pc = (void __user *)instruction_pointer(regs);
 443
 444         if (processor_mode(regs) == SVC_MODE) {
 445 #ifdef CONFIG_THUMB2_KERNEL
 446                 if (thumb_mode(regs)) {
 447                         instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
 448                         if (is_wide_instruction(instr)) {
 449                                 u16 inst2;
 450                                 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
 451                                 instr = __opcode_thumb32_compose(instr, inst2);
 452                         }
 453                 } else
 454 #endif
 455                         instr = __mem_to_opcode_arm(*(u32 *) pc);
 456         } else if (thumb_mode(regs)) {
 457                 if (get_user(instr, (u16 __user *)pc))
 458                         goto die_sig;
 459                 instr = __mem_to_opcode_thumb16(instr);
 460                 if (is_wide_instruction(instr)) {
 461                         unsigned int instr2;
 462                         if (get_user(instr2, (u16 __user *)pc+1))
 463                                 goto die_sig;
 464                         instr2 = __mem_to_opcode_thumb16(instr2);
 465                         instr = __opcode_thumb32_compose(instr, instr2);
 466                 }
 467         } else {
 468                 if (get_user(instr, (u32 __user *)pc))
 469                         goto die_sig;
 470                 instr = __mem_to_opcode_arm(instr);
 471         }
 472
 473         if (call_undef_hook(regs, instr) == 0)
 474                 return;
 475
 476 die_sig:
 477 #ifdef CONFIG_DEBUG_USER
 478         if (user_debug & UDBG_UNDEFINED) {
 479                 pr_info("%s (%d): undefined instruction: pc=%p\n",
 480                         current->comm, task_pid_nr(current), pc);
 481                 __show_regs(regs);
 482                 dump_instr(KERN_INFO, regs);
 483         }
 484 #endif
 485
 486         info.si_signo = SIGILL;
 487         info.si_errno = 0;
 488         info.si_code  = ILL_ILLOPC;
 489         info.si_addr  = pc;
 490
 491         arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
 492 }
 493
 494 /*
 495  * Handle FIQ similarly to NMI on x86 systems.
 496  *
 497  * The runtime environment for NMIs is extremely restrictive
 498  * (NMIs can pre-empt critical sections meaning almost all locking is
 499  * forbidden) meaning this default FIQ handling must only be used in
 500  * circumstances where non-maskability improves robustness, such as
 501  * watchdog or debug logic.
 502  *
 503  * This handler is not appropriate for general purpose use in drivers
 504  * platform code and can be overrideen using set_fiq_handler.
 505  */
 506 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
 507 {
 508         struct pt_regs *old_regs = set_irq_regs(regs);
 509
 510         nmi_enter();
 511
 512         /* nop. FIQ handlers for special arch/arm features can be added here. */
 513
 514         nmi_exit();
 515
 516         set_irq_regs(old_regs);
 517 }
 518
 519 /*
 520  * bad_mode handles the impossible case in the vectors.  If you see one of
 521  * these, then it's extremely serious, and could mean you have buggy hardware.
 522  * It never returns, and never tries to sync.  We hope that we can at least
 523  * dump out some state information...
 524  */
 525 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
 526 {
 527         console_verbose();
 528
 529         pr_crit("Bad mode in %s handler detected\n", handler[reason]);
 530
 531         die("Oops - bad mode", regs, 0);
 532         local_irq_disable();
 533         panic("bad mode");
 534 }
 535
 536 static int bad_syscall(int n, struct pt_regs *regs)
 537 {
 538         siginfo_t info;
 539
 540         if ((current->personality & PER_MASK) != PER_LINUX) {
 541                 send_sig(SIGSEGV, current, 1);
 542                 return regs->ARM_r0;
 543         }
 544
 545 #ifdef CONFIG_DEBUG_USER
 546         if (user_debug & UDBG_SYSCALL) {
 547                 pr_err("[%d] %s: obsolete system call %08x.\n",
 548                         task_pid_nr(current), current->comm, n);
 549                 dump_instr(KERN_ERR, regs);
 550         }
 551 #endif
 552
 553         info.si_signo = SIGILL;
 554         info.si_errno = 0;
 555         info.si_code  = ILL_ILLTRP;
 556         info.si_addr  = (void __user *)instruction_pointer(regs) -
 557                          (thumb_mode(regs) ? 2 : 4);
 558
 559         arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
 560
 561         return regs->ARM_r0;
 562 }
 563
 564 static inline int
 565 __do_cache_op(unsigned long start, unsigned long end)
 566 {
 567         int ret;
 568
 569         do {
 570                 unsigned long chunk = min(PAGE_SIZE, end - start);
 571
 572                 if (fatal_signal_pending(current))
 573                         return 0;
 574
 575                 ret = flush_cache_user_range(start, start + chunk);
 576                 if (ret)
 577                         return ret;
 578
 579                 cond_resched();
 580                 start += chunk;
 581         } while (start < end);
 582
 583         return 0;
 584 }
 585
 586 static inline int
 587 do_cache_op(unsigned long start, unsigned long end, int flags)
 588 {
 589         if (end < start || flags)
 590                 return -EINVAL;
 591
 592         if (!access_ok(VERIFY_READ, start, end - start))
 593                 return -EFAULT;
 594
 595         return __do_cache_op(start, end);
 596 }
 597
 598 /*
 599  * Handle all unrecognised system calls.
 600  *  0x9f0000 - 0x9fffff are some more esoteric system calls
 601  */
 602 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
 603 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
 604 {
 605         siginfo_t info;
 606
 607         if ((no >> 16) != (__ARM_NR_BASE>> 16))
 608                 return bad_syscall(no, regs);
 609
 610         switch (no & 0xffff) {
 611         case 0: /* branch through 0 */
 612                 info.si_signo = SIGSEGV;
 613                 info.si_errno = 0;
 614                 info.si_code  = SEGV_MAPERR;
 615                 info.si_addr  = NULL;
 616
 617                 arm_notify_die("branch through zero", regs, &info, 0, 0);
 618                 return 0;
 619
 620         case NR(breakpoint): /* SWI BREAK_POINT */
 621                 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 622                 ptrace_break(current, regs);
 623                 return regs->ARM_r0;
 624
 625         /*
 626          * Flush a region from virtual address 'r0' to virtual address 'r1'
 627          * _exclusive_.  There is no alignment requirement on either address;
 628          * user space does not need to know the hardware cache layout.
 629          *
 630          * r2 contains flags.  It should ALWAYS be passed as ZERO until it
 631          * is defined to be something else.  For now we ignore it, but may
 632          * the fires of hell burn in your belly if you break this rule. ;)
 633          *
 634          * (at a later date, we may want to allow this call to not flush
 635          * various aspects of the cache.  Passing '0' will guarantee that
 636          * everything necessary gets flushed to maintain consistency in
 637          * the specified region).
 638          */
 639         case NR(cacheflush):
 640                 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
 641
 642         case NR(usr26):
 643                 if (!(elf_hwcap & HWCAP_26BIT))
 644                         break;
 645                 regs->ARM_cpsr &= ~MODE32_BIT;
 646                 return regs->ARM_r0;
 647
 648         case NR(usr32):
 649                 if (!(elf_hwcap & HWCAP_26BIT))
 650                         break;
 651                 regs->ARM_cpsr |= MODE32_BIT;
 652                 return regs->ARM_r0;
 653
 654         case NR(set_tls):
 655                 set_tls(regs->ARM_r0);
 656                 return 0;
 657
 658         case NR(get_tls):
 659                 return current_thread_info()->tp_value[0];
 660
 661         default:
 662                 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
 663                    if not implemented, rather than raising SIGILL.  This
 664                    way the calling program can gracefully determine whether
 665                    a feature is supported.  */
 666                 if ((no & 0xffff) <= 0x7ff)
 667                         return -ENOSYS;
 668                 break;
 669         }
 670 #ifdef CONFIG_DEBUG_USER
 671         /*
 672          * experience shows that these seem to indicate that
 673          * something catastrophic has happened
 674          */
 675         if (user_debug & UDBG_SYSCALL) {
 676                 pr_err("[%d] %s: arm syscall %d\n",
 677                        task_pid_nr(current), current->comm, no);
 678                 dump_instr("", regs);
 679                 if (user_mode(regs)) {
 680                         __show_regs(regs);
 681                         c_backtrace(frame_pointer(regs), processor_mode(regs));
 682                 }
 683         }
 684 #endif
 685         info.si_signo = SIGILL;
 686         info.si_errno = 0;
 687         info.si_code  = ILL_ILLTRP;
 688         info.si_addr  = (void __user *)instruction_pointer(regs) -
 689                          (thumb_mode(regs) ? 2 : 4);
 690
 691         arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
 692         return 0;
 693 }
 694
 695 #ifdef CONFIG_TLS_REG_EMUL
 696
 697 /*
 698  * We might be running on an ARMv6+ processor which should have the TLS
 699  * register but for some reason we can't use it, or maybe an SMP system
 700  * using a pre-ARMv6 processor (there are apparently a few prototypes like
 701  * that in existence) and therefore access to that register must be
 702  * emulated.
 703  */
 704
 705 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
 706 {
 707         int reg = (instr >> 12) & 15;
 708         if (reg == 15)
 709                 return 1;
 710         regs->uregs[reg] = current_thread_info()->tp_value[0];
 711         regs->ARM_pc += 4;
 712         return 0;
 713 }
 714
 715 static struct undef_hook arm_mrc_hook = {
 716         .instr_mask     = 0x0fff0fff,
 717         .instr_val      = 0x0e1d0f70,
 718         .cpsr_mask      = PSR_T_BIT,
 719         .cpsr_val       = 0,
 720         .fn             = get_tp_trap,
 721 };
 722
 723 static int __init arm_mrc_hook_init(void)
 724 {
 725         register_undef_hook(&arm_mrc_hook);
 726         return 0;
 727 }
 728
 729 late_initcall(arm_mrc_hook_init);
 730
 731 #endif
 732
 733 /*
 734  * A data abort trap was taken, but we did not handle the instruction.
 735  * Try to abort the user program, or panic if it was the kernel.
 736  */
 737 asmlinkage void
 738 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
 739 {
 740         unsigned long addr = instruction_pointer(regs);
 741         siginfo_t info;
 742
 743 #ifdef CONFIG_DEBUG_USER
 744         if (user_debug & UDBG_BADABORT) {
 745                 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
 746                        task_pid_nr(current), current->comm, code, instr);
 747                 dump_instr(KERN_ERR, regs);
 748                 show_pte(current->mm, addr);
 749         }
 750 #endif
 751
 752         info.si_signo = SIGILL;
 753         info.si_errno = 0;
 754         info.si_code  = ILL_ILLOPC;
 755         info.si_addr  = (void __user *)addr;
 756
 757         arm_notify_die("unknown data abort code", regs, &info, instr, 0);
 758 }
 759
 760 void __readwrite_bug(const char *fn)
 761 {
 762         pr_err("%s called, but not implemented\n", fn);
 763         BUG();
 764 }
 765 EXPORT_SYMBOL(__readwrite_bug);
 766
 767 void __pte_error(const char *file, int line, pte_t pte)
 768 {
 769         pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
 770 }
 771
 772 void __pmd_error(const char *file, int line, pmd_t pmd)
 773 {
 774         pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
 775 }
 776
 777 void __pgd_error(const char *file, int line, pgd_t pgd)
 778 {
 779         pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
 780 }
 781
 782 asmlinkage void __div0(void)
 783 {
 784         pr_err("Division by zero in kernel.\n");
 785         dump_stack();
 786 }
 787 EXPORT_SYMBOL(__div0);
 788
 789 void abort(void)
 790 {
 791         BUG();
 792
 793         /* if that doesn't kill us, halt */
 794         panic("Oops failed to kill thread");
 795 }
 796
 797 void __init trap_init(void)
 798 {
 799         return;
 800 }
 801
 802 #ifdef CONFIG_KUSER_HELPERS
 803 static void __init kuser_init(void *vectors)
 804 {
 805         extern char __kuser_helper_start[], __kuser_helper_end[];
 806         int kuser_sz = __kuser_helper_end - __kuser_helper_start;
 807
 808         memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
 809
 810         /*
 811          * vectors + 0xfe0 = __kuser_get_tls
 812          * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
 813          */
 814         if (tls_emu || has_tls_reg)
 815                 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
 816 }
 817 #else
 818 static inline void __init kuser_init(void *vectors)
 819 {
 820 }
 821 #endif
 822
 823 void __init early_trap_init(void *vectors_base)
 824 {
 825 #ifndef CONFIG_CPU_V7M
 826         unsigned long vectors = (unsigned long)vectors_base;
 827         extern char __stubs_start[], __stubs_end[];
 828         extern char __vectors_start[], __vectors_end[];
 829         unsigned i;
 830
 831         vectors_page = vectors_base;
 832
 833         /*
 834          * Poison the vectors page with an undefined instruction.  This
 835          * instruction is chosen to be undefined for both ARM and Thumb
 836          * ISAs.  The Thumb version is an undefined instruction with a
 837          * branch back to the undefined instruction.
 838          */
 839         for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
 840                 ((u32 *)vectors_base)[i] = 0xe7fddef1;
 841
 842         /*
 843          * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
 844          * into the vector page, mapped at 0xffff0000, and ensure these
 845          * are visible to the instruction stream.
 846          */
 847         memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
 848         memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
 849
 850         kuser_init(vectors_base);
 851
 852         flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
 853 #else /* ifndef CONFIG_CPU_V7M */
 854         /*
 855          * on V7-M there is no need to copy the vector table to a dedicated
 856          * memory area. The address is configurable and so a table in the kernel
 857          * image can be used.
 858          */
 859 #endif
 860 }