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