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/signal.h>
  29 #include <linux/sched/debug.h>
  30 #include <linux/sched/task_stack.h>
  31 #include <linux/irq.h>
  32
  33 #include <linux/atomic.h>
  34 #include <asm/cacheflush.h>
  35 #include <asm/exception.h>
  36 #include <asm/unistd.h>
  37 #include <asm/traps.h>
  38 #include <asm/ptrace.h>
  39 #include <asm/unwind.h>
  40 #include <asm/tls.h>
  41 #include <asm/system_misc.h>
  42 #include <asm/opcodes.h>
  43
  44
  45 static const char *handler[]= {
  46         "prefetch abort",
  47         "data abort",
  48         "address exception",
  49         "interrupt",
  50         "undefined instruction",
  51 };
  52
  53 void *vectors_page;
  54
  55 #ifdef CONFIG_DEBUG_USER
  56 unsigned int user_debug;
  57
  58 static int __init user_debug_setup(char *str)
  59 {
  60         get_option(&str, &user_debug);
  61         return 1;
  62 }
  63 __setup("user_debug=", user_debug_setup);
  64 #endif
  65
  66 static void dump_mem(const char *, const char *, unsigned long, unsigned long);
  67
  68 void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
  69 {
  70 #ifdef CONFIG_KALLSYMS
  71         printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
  72 #else
  73         printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
  74 #endif
  75
  76         if (in_exception_text(where))
  77                 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
  78 }
  79
  80 void dump_backtrace_stm(u32 *stack, u32 instruction)
  81 {
  82         char str[80], *p;
  83         unsigned int x;
  84         int reg;
  85
  86         for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
  87                 if (instruction & BIT(reg)) {
  88                         p += sprintf(p, " r%d:%08x", reg, *stack--);
  89                         if (++x == 6) {
  90                                 x = 0;
  91                                 p = str;
  92                                 printk("%s\n", str);
  93                         }
  94                 }
  95         }
  96         if (p != str)
  97                 printk("%s\n", str);
  98 }
  99
 100 #ifndef CONFIG_ARM_UNWIND
 101 /*
 102  * Stack pointers should always be within the kernels view of
 103  * physical memory.  If it is not there, then we can't dump
 104  * out any information relating to the stack.
 105  */
 106 static int verify_stack(unsigned long sp)
 107 {
 108         if (sp < PAGE_OFFSET ||
 109             (sp > (unsigned long)high_memory && high_memory != NULL))
 110                 return -EFAULT;
 111
 112         return 0;
 113 }
 114 #endif
 115
 116 /*
 117  * Dump out the contents of some memory nicely...
 118  */
 119 static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
 120                      unsigned long top)
 121 {
 122         unsigned long first;
 123         mm_segment_t fs;
 124         int i;
 125
 126         /*
 127          * We need to switch to kernel mode so that we can use __get_user
 128          * to safely read from kernel space.  Note that we now dump the
 129          * code first, just in case the backtrace kills us.
 130          */
 131         fs = get_fs();
 132         set_fs(KERNEL_DS);
 133
 134         printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
 135
 136         for (first = bottom & ~31; first < top; first += 32) {
 137                 unsigned long p;
 138                 char str[sizeof(" 12345678") * 8 + 1];
 139
 140                 memset(str, ' ', sizeof(str));
 141                 str[sizeof(str) - 1] = '\0';
 142
 143                 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
 144                         if (p >= bottom && p < top) {
 145                                 unsigned long val;
 146                                 if (__get_user(val, (unsigned long *)p) == 0)
 147                                         sprintf(str + i * 9, " %08lx", val);
 148                                 else
 149                                         sprintf(str + i * 9, " ????????");
 150                         }
 151                 }
 152                 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
 153         }
 154
 155         set_fs(fs);
 156 }
 157
 158 static void __dump_instr(const char *lvl, struct pt_regs *regs)
 159 {
 160         unsigned long addr = instruction_pointer(regs);
 161         const int thumb = thumb_mode(regs);
 162         const int width = thumb ? 4 : 8;
 163         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 164         int i;
 165
 166         /*
 167          * Note that we now dump the code first, just in case the backtrace
 168          * kills us.
 169          */
 170
 171         for (i = -4; i < 1 + !!thumb; i++) {
 172                 unsigned int val, bad;
 173
 174                 if (thumb)
 175                         bad = get_user(val, &((u16 *)addr)[i]);
 176                 else
 177                         bad = get_user(val, &((u32 *)addr)[i]);
 178
 179                 if (!bad)
 180                         p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
 181                                         width, val);
 182                 else {
 183                         p += sprintf(p, "bad PC value");
 184                         break;
 185                 }
 186         }
 187         printk("%sCode: %s\n", lvl, str);
 188 }
 189
 190 static void dump_instr(const char *lvl, struct pt_regs *regs)
 191 {
 192         mm_segment_t fs;
 193
 194         if (!user_mode(regs)) {
 195                 fs = get_fs();
 196                 set_fs(KERNEL_DS);
 197                 __dump_instr(lvl, regs);
 198                 set_fs(fs);
 199         } else {
 200                 __dump_instr(lvl, regs);
 201         }
 202 }
 203
 204 #ifdef CONFIG_ARM_UNWIND
 205 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 206 {
 207         unwind_backtrace(regs, tsk);
 208 }
 209 #else
 210 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 211 {
 212         unsigned int fp, mode;
 213         int ok = 1;
 214
 215         printk("Backtrace: ");
 216
 217         if (!tsk)
 218                 tsk = current;
 219
 220         if (regs) {
 221                 fp = frame_pointer(regs);
 222                 mode = processor_mode(regs);
 223         } else if (tsk != current) {
 224                 fp = thread_saved_fp(tsk);
 225                 mode = 0x10;
 226         } else {
 227                 asm("mov %0, fp" : "=r" (fp) : : "cc");
 228                 mode = 0x10;
 229         }
 230
 231         if (!fp) {
 232                 pr_cont("no frame pointer");
 233                 ok = 0;
 234         } else if (verify_stack(fp)) {
 235                 pr_cont("invalid frame pointer 0x%08x", fp);
 236                 ok = 0;
 237         } else if (fp < (unsigned long)end_of_stack(tsk))
 238                 pr_cont("frame pointer underflow");
 239         pr_cont("\n");
 240
 241         if (ok)
 242                 c_backtrace(fp, mode);
 243 }
 244 #endif
 245
 246 void show_stack(struct task_struct *tsk, unsigned long *sp)
 247 {
 248         dump_backtrace(NULL, tsk);
 249         barrier();
 250 }
 251
 252 #ifdef CONFIG_PREEMPT
 253 #define S_PREEMPT " PREEMPT"
 254 #else
 255 #define S_PREEMPT ""
 256 #endif
 257 #ifdef CONFIG_SMP
 258 #define S_SMP " SMP"
 259 #else
 260 #define S_SMP ""
 261 #endif
 262 #ifdef CONFIG_THUMB2_KERNEL
 263 #define S_ISA " THUMB2"
 264 #else
 265 #define S_ISA " ARM"
 266 #endif
 267
 268 static int __die(const char *str, int err, struct pt_regs *regs)
 269 {
 270         struct task_struct *tsk = current;
 271         static int die_counter;
 272         int ret;
 273
 274         pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
 275                  str, err, ++die_counter);
 276
 277         /* trap and error numbers are mostly meaningless on ARM */
 278         ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
 279         if (ret == NOTIFY_STOP)
 280                 return 1;
 281
 282         print_modules();
 283         __show_regs(regs);
 284         pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
 285                  TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
 286
 287         if (!user_mode(regs) || in_interrupt()) {
 288                 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
 289                          THREAD_SIZE + (unsigned long)task_stack_page(tsk));
 290                 dump_backtrace(regs, tsk);
 291                 dump_instr(KERN_EMERG, regs);
 292         }
 293
 294         return 0;
 295 }
 296
 297 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
 298 static int die_owner = -1;
 299 static unsigned int die_nest_count;
 300
 301 static unsigned long oops_begin(void)
 302 {
 303         int cpu;
 304         unsigned long flags;
 305
 306         oops_enter();
 307
 308         /* racy, but better than risking deadlock. */
 309         raw_local_irq_save(flags);
 310         cpu = smp_processor_id();
 311         if (!arch_spin_trylock(&die_lock)) {
 312                 if (cpu == die_owner)
 313                         /* nested oops. should stop eventually */;
 314                 else
 315                         arch_spin_lock(&die_lock);
 316         }
 317         die_nest_count++;
 318         die_owner = cpu;
 319         console_verbose();
 320         bust_spinlocks(1);
 321         return flags;
 322 }
 323
 324 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
 325 {
 326         if (regs && kexec_should_crash(current))
 327                 crash_kexec(regs);
 328
 329         bust_spinlocks(0);
 330         die_owner = -1;
 331         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 332         die_nest_count--;
 333         if (!die_nest_count)
 334                 /* Nest count reaches zero, release the lock. */
 335                 arch_spin_unlock(&die_lock);
 336         raw_local_irq_restore(flags);
 337         oops_exit();
 338
 339         if (in_interrupt())
 340                 panic("Fatal exception in interrupt");
 341         if (panic_on_oops)
 342                 panic("Fatal exception");
 343         if (signr)
 344                 do_exit(signr);
 345 }
 346
 347 /*
 348  * This function is protected against re-entrancy.
 349  */
 350 void die(const char *str, struct pt_regs *regs, int err)
 351 {
 352         enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
 353         unsigned long flags = oops_begin();
 354         int sig = SIGSEGV;
 355
 356         if (!user_mode(regs))
 357                 bug_type = report_bug(regs->ARM_pc, regs);
 358         if (bug_type != BUG_TRAP_TYPE_NONE)
 359                 str = "Oops - BUG";
 360
 361         if (__die(str, err, regs))
 362                 sig = 0;
 363
 364         oops_end(flags, regs, sig);
 365 }
 366
 367 void arm_notify_die(const char *str, struct pt_regs *regs,
 368                 struct siginfo *info, unsigned long err, unsigned long trap)
 369 {
 370         if (user_mode(regs)) {
 371                 current->thread.error_code = err;
 372                 current->thread.trap_no = trap;
 373
 374                 force_sig_info(info->si_signo, info, current);
 375         } else {
 376                 die(str, regs, err);
 377         }
 378 }
 379
 380 #ifdef CONFIG_GENERIC_BUG
 381
 382 int is_valid_bugaddr(unsigned long pc)
 383 {
 384 #ifdef CONFIG_THUMB2_KERNEL
 385         u16 bkpt;
 386         u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
 387 #else
 388         u32 bkpt;
 389         u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
 390 #endif
 391
 392         if (probe_kernel_address((unsigned *)pc, bkpt))
 393                 return 0;
 394
 395         return bkpt == insn;
 396 }
 397
 398 #endif
 399
 400 static LIST_HEAD(undef_hook);
 401 static DEFINE_RAW_SPINLOCK(undef_lock);
 402
 403 void register_undef_hook(struct undef_hook *hook)
 404 {
 405         unsigned long flags;
 406
 407         raw_spin_lock_irqsave(&undef_lock, flags);
 408         list_add(&hook->node, &undef_hook);
 409         raw_spin_unlock_irqrestore(&undef_lock, flags);
 410 }
 411
 412 void unregister_undef_hook(struct undef_hook *hook)
 413 {
 414         unsigned long flags;
 415
 416         raw_spin_lock_irqsave(&undef_lock, flags);
 417         list_del(&hook->node);
 418         raw_spin_unlock_irqrestore(&undef_lock, flags);
 419 }
 420
 421 static nokprobe_inline
 422 int call_undef_hook(struct pt_regs *regs, unsigned int instr)
 423 {
 424         struct undef_hook *hook;
 425         unsigned long flags;
 426         int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
 427
 428         raw_spin_lock_irqsave(&undef_lock, flags);
 429         list_for_each_entry(hook, &undef_hook, node)
 430                 if ((instr & hook->instr_mask) == hook->instr_val &&
 431                     (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
 432                         fn = hook->fn;
 433         raw_spin_unlock_irqrestore(&undef_lock, flags);
 434
 435         return fn ? fn(regs, instr) : 1;
 436 }
 437
 438 asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
 439 {
 440         unsigned int instr;
 441         siginfo_t info;
 442         void __user *pc;
 443
 444         pc = (void __user *)instruction_pointer(regs);
 445
 446         if (processor_mode(regs) == SVC_MODE) {
 447 #ifdef CONFIG_THUMB2_KERNEL
 448                 if (thumb_mode(regs)) {
 449                         instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
 450                         if (is_wide_instruction(instr)) {
 451                                 u16 inst2;
 452                                 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
 453                                 instr = __opcode_thumb32_compose(instr, inst2);
 454                         }
 455                 } else
 456 #endif
 457                         instr = __mem_to_opcode_arm(*(u32 *) pc);
 458         } else if (thumb_mode(regs)) {
 459                 if (get_user(instr, (u16 __user *)pc))
 460                         goto die_sig;
 461                 instr = __mem_to_opcode_thumb16(instr);
 462                 if (is_wide_instruction(instr)) {
 463                         unsigned int instr2;
 464                         if (get_user(instr2, (u16 __user *)pc+1))
 465                                 goto die_sig;
 466                         instr2 = __mem_to_opcode_thumb16(instr2);
 467                         instr = __opcode_thumb32_compose(instr, instr2);
 468                 }
 469         } else {
 470                 if (get_user(instr, (u32 __user *)pc))
 471                         goto die_sig;
 472                 instr = __mem_to_opcode_arm(instr);
 473         }
 474
 475         if (call_undef_hook(regs, instr) == 0)
 476                 return;
 477
 478 die_sig:
 479 #ifdef CONFIG_DEBUG_USER
 480         if (user_debug & UDBG_UNDEFINED) {
 481                 pr_info("%s (%d): undefined instruction: pc=%p\n",
 482                         current->comm, task_pid_nr(current), pc);
 483                 __show_regs(regs);
 484                 dump_instr(KERN_INFO, regs);
 485         }
 486 #endif
 487
 488         info.si_signo = SIGILL;
 489         info.si_errno = 0;
 490         info.si_code  = ILL_ILLOPC;
 491         info.si_addr  = pc;
 492
 493         arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
 494 }
 495 NOKPROBE_SYMBOL(do_undefinstr)
 496
 497 /*
 498  * Handle FIQ similarly to NMI on x86 systems.
 499  *
 500  * The runtime environment for NMIs is extremely restrictive
 501  * (NMIs can pre-empt critical sections meaning almost all locking is
 502  * forbidden) meaning this default FIQ handling must only be used in
 503  * circumstances where non-maskability improves robustness, such as
 504  * watchdog or debug logic.
 505  *
 506  * This handler is not appropriate for general purpose use in drivers
 507  * platform code and can be overrideen using set_fiq_handler.
 508  */
 509 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
 510 {
 511         struct pt_regs *old_regs = set_irq_regs(regs);
 512
 513         nmi_enter();
 514
 515         /* nop. FIQ handlers for special arch/arm features can be added here. */
 516
 517         nmi_exit();
 518
 519         set_irq_regs(old_regs);
 520 }
 521
 522 /*
 523  * bad_mode handles the impossible case in the vectors.  If you see one of
 524  * these, then it's extremely serious, and could mean you have buggy hardware.
 525  * It never returns, and never tries to sync.  We hope that we can at least
 526  * dump out some state information...
 527  */
 528 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
 529 {
 530         console_verbose();
 531
 532         pr_crit("Bad mode in %s handler detected\n", handler[reason]);
 533
 534         die("Oops - bad mode", regs, 0);
 535         local_irq_disable();
 536         panic("bad mode");
 537 }
 538
 539 static int bad_syscall(int n, struct pt_regs *regs)
 540 {
 541         siginfo_t info;
 542
 543         if ((current->personality & PER_MASK) != PER_LINUX) {
 544                 send_sig(SIGSEGV, current, 1);
 545                 return regs->ARM_r0;
 546         }
 547
 548 #ifdef CONFIG_DEBUG_USER
 549         if (user_debug & UDBG_SYSCALL) {
 550                 pr_err("[%d] %s: obsolete system call %08x.\n",
 551                         task_pid_nr(current), current->comm, n);
 552                 dump_instr(KERN_ERR, regs);
 553         }
 554 #endif
 555
 556         info.si_signo = SIGILL;
 557         info.si_errno = 0;
 558         info.si_code  = ILL_ILLTRP;
 559         info.si_addr  = (void __user *)instruction_pointer(regs) -
 560                          (thumb_mode(regs) ? 2 : 4);
 561
 562         arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
 563
 564         return regs->ARM_r0;
 565 }
 566
 567 static inline int
 568 __do_cache_op(unsigned long start, unsigned long end)
 569 {
 570         int ret;
 571
 572         do {
 573                 unsigned long chunk = min(PAGE_SIZE, end - start);
 574
 575                 if (fatal_signal_pending(current))
 576                         return 0;
 577
 578                 ret = flush_cache_user_range(start, start + chunk);
 579                 if (ret)
 580                         return ret;
 581
 582                 cond_resched();
 583                 start += chunk;
 584         } while (start < end);
 585
 586         return 0;
 587 }
 588
 589 static inline int
 590 do_cache_op(unsigned long start, unsigned long end, int flags)
 591 {
 592         if (end < start || flags)
 593                 return -EINVAL;
 594
 595         if (!access_ok(VERIFY_READ, start, end - start))
 596                 return -EFAULT;
 597
 598         return __do_cache_op(start, end);
 599 }
 600
 601 /*
 602  * Handle all unrecognised system calls.
 603  *  0x9f0000 - 0x9fffff are some more esoteric system calls
 604  */
 605 #define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
 606 asmlinkage int arm_syscall(int no, struct pt_regs *regs)
 607 {
 608         siginfo_t info;
 609
 610         if ((no >> 16) != (__ARM_NR_BASE>> 16))
 611                 return bad_syscall(no, regs);
 612
 613         switch (no & 0xffff) {
 614         case 0: /* branch through 0 */
 615                 info.si_signo = SIGSEGV;
 616                 info.si_errno = 0;
 617                 info.si_code  = SEGV_MAPERR;
 618                 info.si_addr  = NULL;
 619
 620                 arm_notify_die("branch through zero", regs, &info, 0, 0);
 621                 return 0;
 622
 623         case NR(breakpoint): /* SWI BREAK_POINT */
 624                 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 625                 ptrace_break(current, regs);
 626                 return regs->ARM_r0;
 627
 628         /*
 629          * Flush a region from virtual address 'r0' to virtual address 'r1'
 630          * _exclusive_.  There is no alignment requirement on either address;
 631          * user space does not need to know the hardware cache layout.
 632          *
 633          * r2 contains flags.  It should ALWAYS be passed as ZERO until it
 634          * is defined to be something else.  For now we ignore it, but may
 635          * the fires of hell burn in your belly if you break this rule. ;)
 636          *
 637          * (at a later date, we may want to allow this call to not flush
 638          * various aspects of the cache.  Passing '0' will guarantee that
 639          * everything necessary gets flushed to maintain consistency in
 640          * the specified region).
 641          */
 642         case NR(cacheflush):
 643                 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
 644
 645         case NR(usr26):
 646                 if (!(elf_hwcap & HWCAP_26BIT))
 647                         break;
 648                 regs->ARM_cpsr &= ~MODE32_BIT;
 649                 return regs->ARM_r0;
 650
 651         case NR(usr32):
 652                 if (!(elf_hwcap & HWCAP_26BIT))
 653                         break;
 654                 regs->ARM_cpsr |= MODE32_BIT;
 655                 return regs->ARM_r0;
 656
 657         case NR(set_tls):
 658                 set_tls(regs->ARM_r0);
 659                 return 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 }