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