arch/arm/kernel/traps.c

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