root/arch/arm/kernel/traps.c

DEFINITIONS

1. user_debug_setup
2. dump_backtrace_entry
3. dump_backtrace_stm
4. verify_stack
5. dump_mem
6. __dump_instr
7. dump_instr
8. dump_backtrace
9. dump_backtrace
10. show_stack
11. __die
12. oops_begin
13. oops_end
14. die
15. arm_notify_die
16. is_valid_bugaddr
17. register_undef_hook
18. unregister_undef_hook
19. call_undef_hook
20. do_undefinstr
21. NOKPROBE_SYMBOL
22. bad_mode
23. bad_syscall
24. __do_cache_op
25. do_cache_op
26. arm_syscall
27. get_tp_trap
28. arm_mrc_hook_init
29. baddataabort
30. __readwrite_bug
31. __pte_error
32. __pmd_error
33. __pgd_error
34. __div0
35. abort
36. trap_init
37. kuser_init
38. kuser_init
39. early_trap_init

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/arch/arm/kernel/traps.c
   4  *
   5  *  Copyright (C) 1995-2009 Russell King
   6  *  Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
   7  *
   8  *  'traps.c' handles hardware exceptions after we have saved some state in
   9  *  'linux/arch/arm/lib/traps.S'.  Mostly a debugging aid, but will probably
  10  *  kill the offending process.
  11  */
  12 #include <linux/signal.h>
  13 #include <linux/personality.h>
  14 #include <linux/kallsyms.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/uaccess.h>
  17 #include <linux/hardirq.h>
  18 #include <linux/kdebug.h>
  19 #include <linux/kprobes.h>
  20 #include <linux/module.h>
  21 #include <linux/kexec.h>
  22 #include <linux/bug.h>
  23 #include <linux/delay.h>
  24 #include <linux/init.h>
  25 #include <linux/sched/signal.h>
  26 #include <linux/sched/debug.h>
  27 #include <linux/sched/task_stack.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_entry_text(from))
  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         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
 161         int i;
 162 
 163         /*
 164          * Note that we now dump the code first, just in case the backtrace
 165          * kills us.
 166          */
 167 
 168         for (i = -4; i < 1 + !!thumb; i++) {
 169                 unsigned int val, bad;
 170 
 171                 if (thumb)
 172                         bad = get_user(val, &((u16 *)addr)[i]);
 173                 else
 174                         bad = get_user(val, &((u32 *)addr)[i]);
 175 
 176                 if (!bad)
 177                         p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
 178                                         width, val);
 179                 else {
 180                         p += sprintf(p, "bad PC value");
 181                         break;
 182                 }
 183         }
 184         printk("%sCode: %s\n", lvl, str);
 185 }
 186 
 187 static void dump_instr(const char *lvl, struct pt_regs *regs)
 188 {
 189         mm_segment_t fs;
 190 
 191         if (!user_mode(regs)) {
 192                 fs = get_fs();
 193                 set_fs(KERNEL_DS);
 194                 __dump_instr(lvl, regs);
 195                 set_fs(fs);
 196         } else {
 197                 __dump_instr(lvl, regs);
 198         }
 199 }
 200 
 201 #ifdef CONFIG_ARM_UNWIND
 202 static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 203 {
 204         unwind_backtrace(regs, tsk);
 205 }
 206 #else
 207 static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 208 {
 209         unsigned int fp, mode;
 210         int ok = 1;
 211 
 212         printk("Backtrace: ");
 213 
 214         if (!tsk)
 215                 tsk = current;
 216 
 217         if (regs) {
 218                 fp = frame_pointer(regs);
 219                 mode = processor_mode(regs);
 220         } else if (tsk != current) {
 221                 fp = thread_saved_fp(tsk);
 222                 mode = 0x10;
 223         } else {
 224                 asm("mov %0, fp" : "=r" (fp) : : "cc");
 225                 mode = 0x10;
 226         }
 227 
 228         if (!fp) {
 229                 pr_cont("no frame pointer");
 230                 ok = 0;
 231         } else if (verify_stack(fp)) {
 232                 pr_cont("invalid frame pointer 0x%08x", fp);
 233                 ok = 0;
 234         } else if (fp < (unsigned long)end_of_stack(tsk))
 235                 pr_cont("frame pointer underflow");
 236         pr_cont("\n");
 237 
 238         if (ok)
 239                 c_backtrace(fp, mode);
 240 }
 241 #endif
 242 
 243 void show_stack(struct task_struct *tsk, unsigned long *sp)
 244 {
 245         dump_backtrace(NULL, tsk);
 246         barrier();
 247 }
 248 
 249 #ifdef CONFIG_PREEMPT
 250 #define S_PREEMPT " PREEMPT"
 251 #else
 252 #define S_PREEMPT ""
 253 #endif
 254 #ifdef CONFIG_SMP
 255 #define S_SMP " SMP"
 256 #else
 257 #define S_SMP ""
 258 #endif
 259 #ifdef CONFIG_THUMB2_KERNEL
 260 #define S_ISA " THUMB2"
 261 #else
 262 #define S_ISA " ARM"
 263 #endif
 264 
 265 static int __die(const char *str, int err, struct pt_regs *regs)
 266 {
 267         struct task_struct *tsk = current;
 268         static int die_counter;
 269         int ret;
 270 
 271         pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
 272                  str, err, ++die_counter);
 273 
 274         /* trap and error numbers are mostly meaningless on ARM */
 275         ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
 276         if (ret == NOTIFY_STOP)
 277                 return 1;
 278 
 279         print_modules();
 280         __show_regs(regs);
 281         pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
 282                  TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
 283 
 284         if (!user_mode(regs) || in_interrupt()) {
 285                 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
 286                          THREAD_SIZE + (unsigned long)task_stack_page(tsk));
 287                 dump_backtrace(regs, tsk);
 288                 dump_instr(KERN_EMERG, regs);
 289         }
 290 
 291         return 0;
 292 }
 293 
 294 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
 295 static int die_owner = -1;
 296 static unsigned int die_nest_count;
 297 
 298 static unsigned long oops_begin(void)
 299 {
 300         int cpu;
 301         unsigned long flags;
 302 
 303         oops_enter();
 304 
 305         /* racy, but better than risking deadlock. */
 306         raw_local_irq_save(flags);
 307         cpu = smp_processor_id();
 308         if (!arch_spin_trylock(&die_lock)) {
 309                 if (cpu == die_owner)
 310                         /* nested oops. should stop eventually */;
 311                 else
 312                         arch_spin_lock(&die_lock);
 313         }
 314         die_nest_count++;
 315         die_owner = cpu;
 316         console_verbose();
 317         bust_spinlocks(1);
 318         return flags;
 319 }
 320 
 321 static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
 322 {
 323         if (regs && kexec_should_crash(current))
 324                 crash_kexec(regs);
 325 
 326         bust_spinlocks(0);
 327         die_owner = -1;
 328         add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
 329         die_nest_count--;
 330         if (!die_nest_count)
 331                 /* Nest count reaches zero, release the lock. */
 332                 arch_spin_unlock(&die_lock);
 333         raw_local_irq_restore(flags);
 334         oops_exit();
 335 
 336         if (in_interrupt())
 337                 panic("Fatal exception in interrupt");
 338         if (panic_on_oops)
 339                 panic("Fatal exception");
 340         if (signr)
 341                 do_exit(signr);
 342 }
 343 
 344 /*
 345  * This function is protected against re-entrancy.
 346  */
 347 void die(const char *str, struct pt_regs *regs, int err)
 348 {
 349         enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
 350         unsigned long flags = oops_begin();
 351         int sig = SIGSEGV;
 352 
 353         if (!user_mode(regs))
 354                 bug_type = report_bug(regs->ARM_pc, regs);
 355         if (bug_type != BUG_TRAP_TYPE_NONE)
 356                 str = "Oops - BUG";
 357 
 358         if (__die(str, err, regs))
 359                 sig = 0;
 360 
 361         oops_end(flags, regs, sig);
 362 }
 363 
 364 void arm_notify_die(const char *str, struct pt_regs *regs,
 365                 int signo, int si_code, void __user *addr,
 366                 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_fault(signo, si_code, addr);
 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 do_undefinstr(struct pt_regs *regs)
 437 {
 438         unsigned int instr;
 439         void __user *pc;
 440 
 441         pc = (void __user *)instruction_pointer(regs);
 442 
 443         if (processor_mode(regs) == SVC_MODE) {
 444 #ifdef CONFIG_THUMB2_KERNEL
 445                 if (thumb_mode(regs)) {
 446                         instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
 447                         if (is_wide_instruction(instr)) {
 448                                 u16 inst2;
 449                                 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
 450                                 instr = __opcode_thumb32_compose(instr, inst2);
 451                         }
 452                 } else
 453 #endif
 454                         instr = __mem_to_opcode_arm(*(u32 *) pc);
 455         } else if (thumb_mode(regs)) {
 456                 if (get_user(instr, (u16 __user *)pc))
 457                         goto die_sig;
 458                 instr = __mem_to_opcode_thumb16(instr);
 459                 if (is_wide_instruction(instr)) {
 460                         unsigned int instr2;
 461                         if (get_user(instr2, (u16 __user *)pc+1))
 462                                 goto die_sig;
 463                         instr2 = __mem_to_opcode_thumb16(instr2);
 464                         instr = __opcode_thumb32_compose(instr, instr2);
 465                 }
 466         } else {
 467                 if (get_user(instr, (u32 __user *)pc))
 468                         goto die_sig;
 469                 instr = __mem_to_opcode_arm(instr);
 470         }
 471 
 472         if (call_undef_hook(regs, instr) == 0)
 473                 return;
 474 
 475 die_sig:
 476 #ifdef CONFIG_DEBUG_USER
 477         if (user_debug & UDBG_UNDEFINED) {
 478                 pr_info("%s (%d): undefined instruction: pc=%p\n",
 479                         current->comm, task_pid_nr(current), pc);
 480                 __show_regs(regs);
 481                 dump_instr(KERN_INFO, regs);
 482         }
 483 #endif
 484         arm_notify_die("Oops - undefined instruction", regs,
 485                        SIGILL, ILL_ILLOPC, pc, 0, 6);
 486 }
 487 NOKPROBE_SYMBOL(do_undefinstr)
 488 
 489 /*
 490  * Handle FIQ similarly to NMI on x86 systems.
 491  *
 492  * The runtime environment for NMIs is extremely restrictive
 493  * (NMIs can pre-empt critical sections meaning almost all locking is
 494  * forbidden) meaning this default FIQ handling must only be used in
 495  * circumstances where non-maskability improves robustness, such as
 496  * watchdog or debug logic.
 497  *
 498  * This handler is not appropriate for general purpose use in drivers
 499  * platform code and can be overrideen using set_fiq_handler.
 500  */
 501 asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
 502 {
 503         struct pt_regs *old_regs = set_irq_regs(regs);
 504 
 505         nmi_enter();
 506 
 507         /* nop. FIQ handlers for special arch/arm features can be added here. */
 508 
 509         nmi_exit();
 510 
 511         set_irq_regs(old_regs);
 512 }
 513 
 514 /*
 515  * bad_mode handles the impossible case in the vectors.  If you see one of
 516  * these, then it's extremely serious, and could mean you have buggy hardware.
 517  * It never returns, and never tries to sync.  We hope that we can at least
 518  * dump out some state information...
 519  */
 520 asmlinkage void bad_mode(struct pt_regs *regs, int reason)
 521 {
 522         console_verbose();
 523 
 524         pr_crit("Bad mode in %s handler detected\n", handler[reason]);
 525 
 526         die("Oops - bad mode", regs, 0);
 527         local_irq_disable();
 528         panic("bad mode");
 529 }
 530 
 531 static int bad_syscall(int n, struct pt_regs *regs)
 532 {
 533         if ((current->personality & PER_MASK) != PER_LINUX) {
 534                 send_sig(SIGSEGV, current, 1);
 535                 return regs->ARM_r0;
 536         }
 537 
 538 #ifdef CONFIG_DEBUG_USER
 539         if (user_debug & UDBG_SYSCALL) {
 540                 pr_err("[%d] %s: obsolete system call %08x.\n",
 541                         task_pid_nr(current), current->comm, n);
 542                 dump_instr(KERN_ERR, regs);
 543         }
 544 #endif
 545 
 546         arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
 547                        (void __user *)instruction_pointer(regs) -
 548                          (thumb_mode(regs) ? 2 : 4),
 549                        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(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         if ((no >> 16) != (__ARM_NR_BASE>> 16))
 596                 return bad_syscall(no, regs);
 597 
 598         switch (no & 0xffff) {
 599         case 0: /* branch through 0 */
 600                 arm_notify_die("branch through zero", regs,
 601                                SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
 602                 return 0;
 603 
 604         case NR(breakpoint): /* SWI BREAK_POINT */
 605                 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
 606                 ptrace_break(regs);
 607                 return regs->ARM_r0;
 608 
 609         /*
 610          * Flush a region from virtual address 'r0' to virtual address 'r1'
 611          * _exclusive_.  There is no alignment requirement on either address;
 612          * user space does not need to know the hardware cache layout.
 613          *
 614          * r2 contains flags.  It should ALWAYS be passed as ZERO until it
 615          * is defined to be something else.  For now we ignore it, but may
 616          * the fires of hell burn in your belly if you break this rule. ;)
 617          *
 618          * (at a later date, we may want to allow this call to not flush
 619          * various aspects of the cache.  Passing '0' will guarantee that
 620          * everything necessary gets flushed to maintain consistency in
 621          * the specified region).
 622          */
 623         case NR(cacheflush):
 624                 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
 625 
 626         case NR(usr26):
 627                 if (!(elf_hwcap & HWCAP_26BIT))
 628                         break;
 629                 regs->ARM_cpsr &= ~MODE32_BIT;
 630                 return regs->ARM_r0;
 631 
 632         case NR(usr32):
 633                 if (!(elf_hwcap & HWCAP_26BIT))
 634                         break;
 635                 regs->ARM_cpsr |= MODE32_BIT;
 636                 return regs->ARM_r0;
 637 
 638         case NR(set_tls):
 639                 set_tls(regs->ARM_r0);
 640                 return 0;
 641 
 642         case NR(get_tls):
 643                 return current_thread_info()->tp_value[0];
 644 
 645         default:
 646                 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
 647                    if not implemented, rather than raising SIGILL.  This
 648                    way the calling program can gracefully determine whether
 649                    a feature is supported.  */
 650                 if ((no & 0xffff) <= 0x7ff)
 651                         return -ENOSYS;
 652                 break;
 653         }
 654 #ifdef CONFIG_DEBUG_USER
 655         /*
 656          * experience shows that these seem to indicate that
 657          * something catastrophic has happened
 658          */
 659         if (user_debug & UDBG_SYSCALL) {
 660                 pr_err("[%d] %s: arm syscall %d\n",
 661                        task_pid_nr(current), current->comm, no);
 662                 dump_instr("", regs);
 663                 if (user_mode(regs)) {
 664                         __show_regs(regs);
 665                         c_backtrace(frame_pointer(regs), processor_mode(regs));
 666                 }
 667         }
 668 #endif
 669         arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
 670                        (void __user *)instruction_pointer(regs) -
 671                          (thumb_mode(regs) ? 2 : 4),
 672                        no, 0);
 673         return 0;
 674 }
 675 
 676 #ifdef CONFIG_TLS_REG_EMUL
 677 
 678 /*
 679  * We might be running on an ARMv6+ processor which should have the TLS
 680  * register but for some reason we can't use it, or maybe an SMP system
 681  * using a pre-ARMv6 processor (there are apparently a few prototypes like
 682  * that in existence) and therefore access to that register must be
 683  * emulated.
 684  */
 685 
 686 static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
 687 {
 688         int reg = (instr >> 12) & 15;
 689         if (reg == 15)
 690                 return 1;
 691         regs->uregs[reg] = current_thread_info()->tp_value[0];
 692         regs->ARM_pc += 4;
 693         return 0;
 694 }
 695 
 696 static struct undef_hook arm_mrc_hook = {
 697         .instr_mask     = 0x0fff0fff,
 698         .instr_val      = 0x0e1d0f70,
 699         .cpsr_mask      = PSR_T_BIT,
 700         .cpsr_val       = 0,
 701         .fn             = get_tp_trap,
 702 };
 703 
 704 static int __init arm_mrc_hook_init(void)
 705 {
 706         register_undef_hook(&arm_mrc_hook);
 707         return 0;
 708 }
 709 
 710 late_initcall(arm_mrc_hook_init);
 711 
 712 #endif
 713 
 714 /*
 715  * A data abort trap was taken, but we did not handle the instruction.
 716  * Try to abort the user program, or panic if it was the kernel.
 717  */
 718 asmlinkage void
 719 baddataabort(int code, unsigned long instr, struct pt_regs *regs)
 720 {
 721         unsigned long addr = instruction_pointer(regs);
 722 
 723 #ifdef CONFIG_DEBUG_USER
 724         if (user_debug & UDBG_BADABORT) {
 725                 pr_err("8<--- cut here ---\n");
 726                 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
 727                        task_pid_nr(current), current->comm, code, instr);
 728                 dump_instr(KERN_ERR, regs);
 729                 show_pte(KERN_ERR, current->mm, addr);
 730         }
 731 #endif
 732 
 733         arm_notify_die("unknown data abort code", regs,
 734                        SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
 735 }
 736 
 737 void __readwrite_bug(const char *fn)
 738 {
 739         pr_err("%s called, but not implemented\n", fn);
 740         BUG();
 741 }
 742 EXPORT_SYMBOL(__readwrite_bug);
 743 
 744 void __pte_error(const char *file, int line, pte_t pte)
 745 {
 746         pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
 747 }
 748 
 749 void __pmd_error(const char *file, int line, pmd_t pmd)
 750 {
 751         pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
 752 }
 753 
 754 void __pgd_error(const char *file, int line, pgd_t pgd)
 755 {
 756         pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
 757 }
 758 
 759 asmlinkage void __div0(void)
 760 {
 761         pr_err("Division by zero in kernel.\n");
 762         dump_stack();
 763 }
 764 EXPORT_SYMBOL(__div0);
 765 
 766 void abort(void)
 767 {
 768         BUG();
 769 
 770         /* if that doesn't kill us, halt */
 771         panic("Oops failed to kill thread");
 772 }
 773 
 774 void __init trap_init(void)
 775 {
 776         return;
 777 }
 778 
 779 #ifdef CONFIG_KUSER_HELPERS
 780 static void __init kuser_init(void *vectors)
 781 {
 782         extern char __kuser_helper_start[], __kuser_helper_end[];
 783         int kuser_sz = __kuser_helper_end - __kuser_helper_start;
 784 
 785         memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
 786 
 787         /*
 788          * vectors + 0xfe0 = __kuser_get_tls
 789          * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
 790          */
 791         if (tls_emu || has_tls_reg)
 792                 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
 793 }
 794 #else
 795 static inline void __init kuser_init(void *vectors)
 796 {
 797 }
 798 #endif
 799 
 800 void __init early_trap_init(void *vectors_base)
 801 {
 802 #ifndef CONFIG_CPU_V7M
 803         unsigned long vectors = (unsigned long)vectors_base;
 804         extern char __stubs_start[], __stubs_end[];
 805         extern char __vectors_start[], __vectors_end[];
 806         unsigned i;
 807 
 808         vectors_page = vectors_base;
 809 
 810         /*
 811          * Poison the vectors page with an undefined instruction.  This
 812          * instruction is chosen to be undefined for both ARM and Thumb
 813          * ISAs.  The Thumb version is an undefined instruction with a
 814          * branch back to the undefined instruction.
 815          */
 816         for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
 817                 ((u32 *)vectors_base)[i] = 0xe7fddef1;
 818 
 819         /*
 820          * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
 821          * into the vector page, mapped at 0xffff0000, and ensure these
 822          * are visible to the instruction stream.
 823          */
 824         memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
 825         memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
 826 
 827         kuser_init(vectors_base);
 828 
 829         flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
 830 #else /* ifndef CONFIG_CPU_V7M */
 831         /*
 832          * on V7-M there is no need to copy the vector table to a dedicated
 833          * memory area. The address is configurable and so a table in the kernel
 834          * image can be used.
 835          */
 836 #endif
 837 }