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