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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
29#include <linux/atomic.h>
30#include <asm/cacheflush.h>
31#include <asm/exception.h>
32#include <asm/unistd.h>
33#include <asm/traps.h>
34#include <asm/unwind.h>
35#include <asm/tls.h>
36#include <asm/system_misc.h>
37#include <asm/opcodes.h>
38
39static const char *handler[]= {
40 "prefetch abort",
41 "data abort",
42 "address exception",
43 "interrupt",
44 "undefined instruction",
45};
46
47void *vectors_page;
48
49#ifdef CONFIG_DEBUG_USER
50unsigned int user_debug;
51
52static int __init user_debug_setup(char *str)
53{
54 get_option(&str, &user_debug);
55 return 1;
56}
57__setup("user_debug=", user_debug_setup);
58#endif
59
60static void dump_mem(const char *, const char *, unsigned long, unsigned long);
61
62void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
63{
64#ifdef CONFIG_KALLSYMS
65 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
66#else
67 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
68#endif
69
70 if (in_exception_text(where))
71 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
72}
73
74#ifndef CONFIG_ARM_UNWIND
75/*
76 * Stack pointers should always be within the kernels view of
77 * physical memory. If it is not there, then we can't dump
78 * out any information relating to the stack.
79 */
80static int verify_stack(unsigned long sp)
81{
82 if (sp < PAGE_OFFSET ||
83 (sp > (unsigned long)high_memory && high_memory != NULL))
84 return -EFAULT;
85
86 return 0;
87}
88#endif
89
90/*
91 * Dump out the contents of some memory nicely...
92 */
93static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
94 unsigned long top)
95{
96 unsigned long first;
97 mm_segment_t fs;
98 int i;
99
100 /*
101 * We need to switch to kernel mode so that we can use __get_user
102 * to safely read from kernel space. Note that we now dump the
103 * code first, just in case the backtrace kills us.
104 */
105 fs = get_fs();
106 set_fs(KERNEL_DS);
107
108 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
109
110 for (first = bottom & ~31; first < top; first += 32) {
111 unsigned long p;
112 char str[sizeof(" 12345678") * 8 + 1];
113
114 memset(str, ' ', sizeof(str));
115 str[sizeof(str) - 1] = '\0';
116
117 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
118 if (p >= bottom && p < top) {
119 unsigned long val;
120 if (__get_user(val, (unsigned long *)p) == 0)
121 sprintf(str + i * 9, " %08lx", val);
122 else
123 sprintf(str + i * 9, " ????????");
124 }
125 }
126 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
127 }
128
129 set_fs(fs);
130}
131
132static void dump_instr(const char *lvl, struct pt_regs *regs)
133{
134 unsigned long addr = instruction_pointer(regs);
135 const int thumb = thumb_mode(regs);
136 const int width = thumb ? 4 : 8;
137 mm_segment_t fs;
138 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
139 int i;
140
141 /*
142 * We need to switch to kernel mode so that we can use __get_user
143 * to safely read from kernel space. Note that we now dump the
144 * code first, just in case the backtrace kills us.
145 */
146 fs = get_fs();
147 set_fs(KERNEL_DS);
148
149 for (i = -4; i < 1 + !!thumb; i++) {
150 unsigned int val, bad;
151
152 if (thumb)
153 bad = __get_user(val, &((u16 *)addr)[i]);
154 else
155 bad = __get_user(val, &((u32 *)addr)[i]);
156
157 if (!bad)
158 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
159 width, val);
160 else {
161 p += sprintf(p, "bad PC value");
162 break;
163 }
164 }
165 printk("%sCode: %s\n", lvl, str);
166
167 set_fs(fs);
168}
169
170#ifdef CONFIG_ARM_UNWIND
171static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
172{
173 unwind_backtrace(regs, tsk);
174}
175#else
176static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
177{
178 unsigned int fp, mode;
179 int ok = 1;
180
181 printk("Backtrace: ");
182
183 if (!tsk)
184 tsk = current;
185
186 if (regs) {
187 fp = regs->ARM_fp;
188 mode = processor_mode(regs);
189 } else if (tsk != current) {
190 fp = thread_saved_fp(tsk);
191 mode = 0x10;
192 } else {
193 asm("mov %0, fp" : "=r" (fp) : : "cc");
194 mode = 0x10;
195 }
196
197 if (!fp) {
198 printk("no frame pointer");
199 ok = 0;
200 } else if (verify_stack(fp)) {
201 printk("invalid frame pointer 0x%08x", fp);
202 ok = 0;
203 } else if (fp < (unsigned long)end_of_stack(tsk))
204 printk("frame pointer underflow");
205 printk("\n");
206
207 if (ok)
208 c_backtrace(fp, mode);
209}
210#endif
211
212void show_stack(struct task_struct *tsk, unsigned long *sp)
213{
214 dump_backtrace(NULL, tsk);
215 barrier();
216}
217
218#ifdef CONFIG_PREEMPT
219#define S_PREEMPT " PREEMPT"
220#else
221#define S_PREEMPT ""
222#endif
223#ifdef CONFIG_SMP
224#define S_SMP " SMP"
225#else
226#define S_SMP ""
227#endif
228#ifdef CONFIG_THUMB2_KERNEL
229#define S_ISA " THUMB2"
230#else
231#define S_ISA " ARM"
232#endif
233
234static int __die(const char *str, int err, struct pt_regs *regs)
235{
236 struct task_struct *tsk = current;
237 static int die_counter;
238 int ret;
239
240 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
241 S_ISA "\n", str, err, ++die_counter);
242
243 /* trap and error numbers are mostly meaningless on ARM */
244 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
245 if (ret == NOTIFY_STOP)
246 return 1;
247
248 print_modules();
249 __show_regs(regs);
250 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
251 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
252
253 if (!user_mode(regs) || in_interrupt()) {
254 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
255 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
256 dump_backtrace(regs, tsk);
257 dump_instr(KERN_EMERG, regs);
258 }
259
260 return 0;
261}
262
263static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
264static int die_owner = -1;
265static unsigned int die_nest_count;
266
267static unsigned long oops_begin(void)
268{
269 int cpu;
270 unsigned long flags;
271
272 oops_enter();
273
274 /* racy, but better than risking deadlock. */
275 raw_local_irq_save(flags);
276 cpu = smp_processor_id();
277 if (!arch_spin_trylock(&die_lock)) {
278 if (cpu == die_owner)
279 /* nested oops. should stop eventually */;
280 else
281 arch_spin_lock(&die_lock);
282 }
283 die_nest_count++;
284 die_owner = cpu;
285 console_verbose();
286 bust_spinlocks(1);
287 return flags;
288}
289
290static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
291{
292 if (regs && kexec_should_crash(current))
293 crash_kexec(regs);
294
295 bust_spinlocks(0);
296 die_owner = -1;
297 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
298 die_nest_count--;
299 if (!die_nest_count)
300 /* Nest count reaches zero, release the lock. */
301 arch_spin_unlock(&die_lock);
302 raw_local_irq_restore(flags);
303 oops_exit();
304
305 if (in_interrupt())
306 panic("Fatal exception in interrupt");
307 if (panic_on_oops)
308 panic("Fatal exception");
309 if (signr)
310 do_exit(signr);
311}
312
313/*
314 * This function is protected against re-entrancy.
315 */
316void die(const char *str, struct pt_regs *regs, int err)
317{
318 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
319 unsigned long flags = oops_begin();
320 int sig = SIGSEGV;
321
322 if (!user_mode(regs))
323 bug_type = report_bug(regs->ARM_pc, regs);
324 if (bug_type != BUG_TRAP_TYPE_NONE)
325 str = "Oops - BUG";
326
327 if (__die(str, err, regs))
328 sig = 0;
329
330 oops_end(flags, regs, sig);
331}
332
333void arm_notify_die(const char *str, struct pt_regs *regs,
334 struct siginfo *info, unsigned long err, unsigned long trap)
335{
336 if (user_mode(regs)) {
337 current->thread.error_code = err;
338 current->thread.trap_no = trap;
339
340 force_sig_info(info->si_signo, info, current);
341 } else {
342 die(str, regs, err);
343 }
344}
345
346#ifdef CONFIG_GENERIC_BUG
347
348int is_valid_bugaddr(unsigned long pc)
349{
350#ifdef CONFIG_THUMB2_KERNEL
351 u16 bkpt;
352 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
353#else
354 u32 bkpt;
355 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
356#endif
357
358 if (probe_kernel_address((unsigned *)pc, bkpt))
359 return 0;
360
361 return bkpt == insn;
362}
363
364#endif
365
366static LIST_HEAD(undef_hook);
367static DEFINE_RAW_SPINLOCK(undef_lock);
368
369void register_undef_hook(struct undef_hook *hook)
370{
371 unsigned long flags;
372
373 raw_spin_lock_irqsave(&undef_lock, flags);
374 list_add(&hook->node, &undef_hook);
375 raw_spin_unlock_irqrestore(&undef_lock, flags);
376}
377
378void unregister_undef_hook(struct undef_hook *hook)
379{
380 unsigned long flags;
381
382 raw_spin_lock_irqsave(&undef_lock, flags);
383 list_del(&hook->node);
384 raw_spin_unlock_irqrestore(&undef_lock, flags);
385}
386
387static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
388{
389 struct undef_hook *hook;
390 unsigned long flags;
391 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
392
393 raw_spin_lock_irqsave(&undef_lock, flags);
394 list_for_each_entry(hook, &undef_hook, node)
395 if ((instr & hook->instr_mask) == hook->instr_val &&
396 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
397 fn = hook->fn;
398 raw_spin_unlock_irqrestore(&undef_lock, flags);
399
400 return fn ? fn(regs, instr) : 1;
401}
402
403asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
404{
405 unsigned int instr;
406 siginfo_t info;
407 void __user *pc;
408
409 pc = (void __user *)instruction_pointer(regs);
410
411 if (processor_mode(regs) == SVC_MODE) {
412#ifdef CONFIG_THUMB2_KERNEL
413 if (thumb_mode(regs)) {
414 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
415 if (is_wide_instruction(instr)) {
416 u16 inst2;
417 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
418 instr = __opcode_thumb32_compose(instr, inst2);
419 }
420 } else
421#endif
422 instr = __mem_to_opcode_arm(*(u32 *) pc);
423 } else if (thumb_mode(regs)) {
424 if (get_user(instr, (u16 __user *)pc))
425 goto die_sig;
426 instr = __mem_to_opcode_thumb16(instr);
427 if (is_wide_instruction(instr)) {
428 unsigned int instr2;
429 if (get_user(instr2, (u16 __user *)pc+1))
430 goto die_sig;
431 instr2 = __mem_to_opcode_thumb16(instr2);
432 instr = __opcode_thumb32_compose(instr, instr2);
433 }
434 } else {
435 if (get_user(instr, (u32 __user *)pc))
436 goto die_sig;
437 instr = __mem_to_opcode_arm(instr);
438 }
439
440 if (call_undef_hook(regs, instr) == 0)
441 return;
442
443die_sig:
444#ifdef CONFIG_DEBUG_USER
445 if (user_debug & UDBG_UNDEFINED) {
446 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
447 current->comm, task_pid_nr(current), pc);
448 __show_regs(regs);
449 dump_instr(KERN_INFO, regs);
450 }
451#endif
452
453 info.si_signo = SIGILL;
454 info.si_errno = 0;
455 info.si_code = ILL_ILLOPC;
456 info.si_addr = pc;
457
458 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
459}
460
461asmlinkage void do_unexp_fiq (struct pt_regs *regs)
462{
463 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
464 printk("You may have a hardware problem...\n");
465}
466
467/*
468 * bad_mode handles the impossible case in the vectors. If you see one of
469 * these, then it's extremely serious, and could mean you have buggy hardware.
470 * It never returns, and never tries to sync. We hope that we can at least
471 * dump out some state information...
472 */
473asmlinkage void bad_mode(struct pt_regs *regs, int reason)
474{
475 console_verbose();
476
477 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
478
479 die("Oops - bad mode", regs, 0);
480 local_irq_disable();
481 panic("bad mode");
482}
483
484static int bad_syscall(int n, struct pt_regs *regs)
485{
486 struct thread_info *thread = current_thread_info();
487 siginfo_t info;
488
489 if ((current->personality & PER_MASK) != PER_LINUX &&
490 thread->exec_domain->handler) {
491 thread->exec_domain->handler(n, regs);
492 return regs->ARM_r0;
493 }
494
495#ifdef CONFIG_DEBUG_USER
496 if (user_debug & UDBG_SYSCALL) {
497 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
498 task_pid_nr(current), current->comm, n);
499 dump_instr(KERN_ERR, regs);
500 }
501#endif
502
503 info.si_signo = SIGILL;
504 info.si_errno = 0;
505 info.si_code = ILL_ILLTRP;
506 info.si_addr = (void __user *)instruction_pointer(regs) -
507 (thumb_mode(regs) ? 2 : 4);
508
509 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
510
511 return regs->ARM_r0;
512}
513
514static long do_cache_op_restart(struct restart_block *);
515
516static inline int
517__do_cache_op(unsigned long start, unsigned long end)
518{
519 int ret;
520
521 do {
522 unsigned long chunk = min(PAGE_SIZE, end - start);
523
524 if (signal_pending(current)) {
525 struct thread_info *ti = current_thread_info();
526
527 ti->restart_block = (struct restart_block) {
528 .fn = do_cache_op_restart,
529 };
530
531 ti->arm_restart_block = (struct arm_restart_block) {
532 {
533 .cache = {
534 .start = start,
535 .end = end,
536 },
537 },
538 };
539
540 return -ERESTART_RESTARTBLOCK;
541 }
542
543 ret = flush_cache_user_range(start, start + chunk);
544 if (ret)
545 return ret;
546
547 cond_resched();
548 start += chunk;
549 } while (start < end);
550
551 return 0;
552}
553
554static long do_cache_op_restart(struct restart_block *unused)
555{
556 struct arm_restart_block *restart_block;
557
558 restart_block = ¤t_thread_info()->arm_restart_block;
559 return __do_cache_op(restart_block->cache.start,
560 restart_block->cache.end);
561}
562
563static inline int
564do_cache_op(unsigned long start, unsigned long end, int flags)
565{
566 if (end < start || flags)
567 return -EINVAL;
568
569 if (!access_ok(VERIFY_READ, start, end - start))
570 return -EFAULT;
571
572 return __do_cache_op(start, end);
573}
574
575/*
576 * Handle all unrecognised system calls.
577 * 0x9f0000 - 0x9fffff are some more esoteric system calls
578 */
579#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
580asmlinkage int arm_syscall(int no, struct pt_regs *regs)
581{
582 struct thread_info *thread = current_thread_info();
583 siginfo_t info;
584
585 if ((no >> 16) != (__ARM_NR_BASE>> 16))
586 return bad_syscall(no, regs);
587
588 switch (no & 0xffff) {
589 case 0: /* branch through 0 */
590 info.si_signo = SIGSEGV;
591 info.si_errno = 0;
592 info.si_code = SEGV_MAPERR;
593 info.si_addr = NULL;
594
595 arm_notify_die("branch through zero", regs, &info, 0, 0);
596 return 0;
597
598 case NR(breakpoint): /* SWI BREAK_POINT */
599 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
600 ptrace_break(current, regs);
601 return regs->ARM_r0;
602
603 /*
604 * Flush a region from virtual address 'r0' to virtual address 'r1'
605 * _exclusive_. There is no alignment requirement on either address;
606 * user space does not need to know the hardware cache layout.
607 *
608 * r2 contains flags. It should ALWAYS be passed as ZERO until it
609 * is defined to be something else. For now we ignore it, but may
610 * the fires of hell burn in your belly if you break this rule. ;)
611 *
612 * (at a later date, we may want to allow this call to not flush
613 * various aspects of the cache. Passing '0' will guarantee that
614 * everything necessary gets flushed to maintain consistency in
615 * the specified region).
616 */
617 case NR(cacheflush):
618 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
619
620 case NR(usr26):
621 if (!(elf_hwcap & HWCAP_26BIT))
622 break;
623 regs->ARM_cpsr &= ~MODE32_BIT;
624 return regs->ARM_r0;
625
626 case NR(usr32):
627 if (!(elf_hwcap & HWCAP_26BIT))
628 break;
629 regs->ARM_cpsr |= MODE32_BIT;
630 return regs->ARM_r0;
631
632 case NR(set_tls):
633 thread->tp_value[0] = regs->ARM_r0;
634 if (tls_emu)
635 return 0;
636 if (has_tls_reg) {
637 asm ("mcr p15, 0, %0, c13, c0, 3"
638 : : "r" (regs->ARM_r0));
639 } else {
640 /*
641 * User space must never try to access this directly.
642 * Expect your app to break eventually if you do so.
643 * The user helper at 0xffff0fe0 must be used instead.
644 * (see entry-armv.S for details)
645 */
646 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
647 }
648 return 0;
649
650#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
651 /*
652 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
653 * Return zero in r0 if *MEM was changed or non-zero if no exchange
654 * happened. Also set the user C flag accordingly.
655 * If access permissions have to be fixed up then non-zero is
656 * returned and the operation has to be re-attempted.
657 *
658 * *NOTE*: This is a ghost syscall private to the kernel. Only the
659 * __kuser_cmpxchg code in entry-armv.S should be aware of its
660 * existence. Don't ever use this from user code.
661 */
662 case NR(cmpxchg):
663 for (;;) {
664 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
665 struct pt_regs *regs);
666 unsigned long val;
667 unsigned long addr = regs->ARM_r2;
668 struct mm_struct *mm = current->mm;
669 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
670 spinlock_t *ptl;
671
672 regs->ARM_cpsr &= ~PSR_C_BIT;
673 down_read(&mm->mmap_sem);
674 pgd = pgd_offset(mm, addr);
675 if (!pgd_present(*pgd))
676 goto bad_access;
677 pmd = pmd_offset(pgd, addr);
678 if (!pmd_present(*pmd))
679 goto bad_access;
680 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
681 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
682 pte_unmap_unlock(pte, ptl);
683 goto bad_access;
684 }
685 val = *(unsigned long *)addr;
686 val -= regs->ARM_r0;
687 if (val == 0) {
688 *(unsigned long *)addr = regs->ARM_r1;
689 regs->ARM_cpsr |= PSR_C_BIT;
690 }
691 pte_unmap_unlock(pte, ptl);
692 up_read(&mm->mmap_sem);
693 return val;
694
695 bad_access:
696 up_read(&mm->mmap_sem);
697 /* simulate a write access fault */
698 do_DataAbort(addr, 15 + (1 << 11), regs);
699 }
700#endif
701
702 default:
703 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
704 if not implemented, rather than raising SIGILL. This
705 way the calling program can gracefully determine whether
706 a feature is supported. */
707 if ((no & 0xffff) <= 0x7ff)
708 return -ENOSYS;
709 break;
710 }
711#ifdef CONFIG_DEBUG_USER
712 /*
713 * experience shows that these seem to indicate that
714 * something catastrophic has happened
715 */
716 if (user_debug & UDBG_SYSCALL) {
717 printk("[%d] %s: arm syscall %d\n",
718 task_pid_nr(current), current->comm, no);
719 dump_instr("", regs);
720 if (user_mode(regs)) {
721 __show_regs(regs);
722 c_backtrace(regs->ARM_fp, processor_mode(regs));
723 }
724 }
725#endif
726 info.si_signo = SIGILL;
727 info.si_errno = 0;
728 info.si_code = ILL_ILLTRP;
729 info.si_addr = (void __user *)instruction_pointer(regs) -
730 (thumb_mode(regs) ? 2 : 4);
731
732 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
733 return 0;
734}
735
736#ifdef CONFIG_TLS_REG_EMUL
737
738/*
739 * We might be running on an ARMv6+ processor which should have the TLS
740 * register but for some reason we can't use it, or maybe an SMP system
741 * using a pre-ARMv6 processor (there are apparently a few prototypes like
742 * that in existence) and therefore access to that register must be
743 * emulated.
744 */
745
746static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
747{
748 int reg = (instr >> 12) & 15;
749 if (reg == 15)
750 return 1;
751 regs->uregs[reg] = current_thread_info()->tp_value[0];
752 regs->ARM_pc += 4;
753 return 0;
754}
755
756static struct undef_hook arm_mrc_hook = {
757 .instr_mask = 0x0fff0fff,
758 .instr_val = 0x0e1d0f70,
759 .cpsr_mask = PSR_T_BIT,
760 .cpsr_val = 0,
761 .fn = get_tp_trap,
762};
763
764static int __init arm_mrc_hook_init(void)
765{
766 register_undef_hook(&arm_mrc_hook);
767 return 0;
768}
769
770late_initcall(arm_mrc_hook_init);
771
772#endif
773
774void __bad_xchg(volatile void *ptr, int size)
775{
776 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
777 __builtin_return_address(0), ptr, size);
778 BUG();
779}
780EXPORT_SYMBOL(__bad_xchg);
781
782/*
783 * A data abort trap was taken, but we did not handle the instruction.
784 * Try to abort the user program, or panic if it was the kernel.
785 */
786asmlinkage void
787baddataabort(int code, unsigned long instr, struct pt_regs *regs)
788{
789 unsigned long addr = instruction_pointer(regs);
790 siginfo_t info;
791
792#ifdef CONFIG_DEBUG_USER
793 if (user_debug & UDBG_BADABORT) {
794 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
795 task_pid_nr(current), current->comm, code, instr);
796 dump_instr(KERN_ERR, regs);
797 show_pte(current->mm, addr);
798 }
799#endif
800
801 info.si_signo = SIGILL;
802 info.si_errno = 0;
803 info.si_code = ILL_ILLOPC;
804 info.si_addr = (void __user *)addr;
805
806 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
807}
808
809void __readwrite_bug(const char *fn)
810{
811 printk("%s called, but not implemented\n", fn);
812 BUG();
813}
814EXPORT_SYMBOL(__readwrite_bug);
815
816void __pte_error(const char *file, int line, pte_t pte)
817{
818 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
819}
820
821void __pmd_error(const char *file, int line, pmd_t pmd)
822{
823 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
824}
825
826void __pgd_error(const char *file, int line, pgd_t pgd)
827{
828 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
829}
830
831asmlinkage void __div0(void)
832{
833 printk("Division by zero in kernel.\n");
834 dump_stack();
835}
836EXPORT_SYMBOL(__div0);
837
838void abort(void)
839{
840 BUG();
841
842 /* if that doesn't kill us, halt */
843 panic("Oops failed to kill thread");
844}
845EXPORT_SYMBOL(abort);
846
847void __init trap_init(void)
848{
849 return;
850}
851
852#ifdef CONFIG_KUSER_HELPERS
853static void __init kuser_init(void *vectors)
854{
855 extern char __kuser_helper_start[], __kuser_helper_end[];
856 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
857
858 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
859
860 /*
861 * vectors + 0xfe0 = __kuser_get_tls
862 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
863 */
864 if (tls_emu || has_tls_reg)
865 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
866}
867#else
868static inline void __init kuser_init(void *vectors)
869{
870}
871#endif
872
873void __init early_trap_init(void *vectors_base)
874{
875#ifndef CONFIG_CPU_V7M
876 unsigned long vectors = (unsigned long)vectors_base;
877 extern char __stubs_start[], __stubs_end[];
878 extern char __vectors_start[], __vectors_end[];
879 unsigned i;
880
881 vectors_page = vectors_base;
882
883 /*
884 * Poison the vectors page with an undefined instruction. This
885 * instruction is chosen to be undefined for both ARM and Thumb
886 * ISAs. The Thumb version is an undefined instruction with a
887 * branch back to the undefined instruction.
888 */
889 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
890 ((u32 *)vectors_base)[i] = 0xe7fddef1;
891
892 /*
893 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
894 * into the vector page, mapped at 0xffff0000, and ensure these
895 * are visible to the instruction stream.
896 */
897 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
898 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
899
900 kuser_init(vectors_base);
901
902 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
903 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
904#else /* ifndef CONFIG_CPU_V7M */
905 /*
906 * on V7-M there is no need to copy the vector table to a dedicated
907 * memory area. The address is configurable and so a table in the kernel
908 * image can be used.
909 */
910#endif
911}
1/*
2 * linux/arch/arm/kernel/traps.c
3 *
4 * Copyright (C) 1995-2009 Russell King
5 * Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * 'traps.c' handles hardware exceptions after we have saved some state in
12 * 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably
13 * kill the offending process.
14 */
15#include <linux/signal.h>
16#include <linux/personality.h>
17#include <linux/kallsyms.h>
18#include <linux/spinlock.h>
19#include <linux/uaccess.h>
20#include <linux/hardirq.h>
21#include <linux/kdebug.h>
22#include <linux/kprobes.h>
23#include <linux/module.h>
24#include <linux/kexec.h>
25#include <linux/bug.h>
26#include <linux/delay.h>
27#include <linux/init.h>
28#include <linux/sched/signal.h>
29#include <linux/sched/debug.h>
30#include <linux/sched/task_stack.h>
31#include <linux/irq.h>
32
33#include <linux/atomic.h>
34#include <asm/cacheflush.h>
35#include <asm/exception.h>
36#include <asm/unistd.h>
37#include <asm/traps.h>
38#include <asm/ptrace.h>
39#include <asm/unwind.h>
40#include <asm/tls.h>
41#include <asm/system_misc.h>
42#include <asm/opcodes.h>
43
44
45static const char *handler[]= {
46 "prefetch abort",
47 "data abort",
48 "address exception",
49 "interrupt",
50 "undefined instruction",
51};
52
53void *vectors_page;
54
55#ifdef CONFIG_DEBUG_USER
56unsigned int user_debug;
57
58static int __init user_debug_setup(char *str)
59{
60 get_option(&str, &user_debug);
61 return 1;
62}
63__setup("user_debug=", user_debug_setup);
64#endif
65
66static void dump_mem(const char *, const char *, unsigned long, unsigned long);
67
68void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
69{
70#ifdef CONFIG_KALLSYMS
71 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
72#else
73 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
74#endif
75
76 if (in_entry_text(from))
77 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
78}
79
80void dump_backtrace_stm(u32 *stack, u32 instruction)
81{
82 char str[80], *p;
83 unsigned int x;
84 int reg;
85
86 for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
87 if (instruction & BIT(reg)) {
88 p += sprintf(p, " r%d:%08x", reg, *stack--);
89 if (++x == 6) {
90 x = 0;
91 p = str;
92 printk("%s\n", str);
93 }
94 }
95 }
96 if (p != str)
97 printk("%s\n", str);
98}
99
100#ifndef CONFIG_ARM_UNWIND
101/*
102 * Stack pointers should always be within the kernels view of
103 * physical memory. If it is not there, then we can't dump
104 * out any information relating to the stack.
105 */
106static int verify_stack(unsigned long sp)
107{
108 if (sp < PAGE_OFFSET ||
109 (sp > (unsigned long)high_memory && high_memory != NULL))
110 return -EFAULT;
111
112 return 0;
113}
114#endif
115
116/*
117 * Dump out the contents of some memory nicely...
118 */
119static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
120 unsigned long top)
121{
122 unsigned long first;
123 mm_segment_t fs;
124 int i;
125
126 /*
127 * We need to switch to kernel mode so that we can use __get_user
128 * to safely read from kernel space. Note that we now dump the
129 * code first, just in case the backtrace kills us.
130 */
131 fs = get_fs();
132 set_fs(KERNEL_DS);
133
134 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
135
136 for (first = bottom & ~31; first < top; first += 32) {
137 unsigned long p;
138 char str[sizeof(" 12345678") * 8 + 1];
139
140 memset(str, ' ', sizeof(str));
141 str[sizeof(str) - 1] = '\0';
142
143 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
144 if (p >= bottom && p < top) {
145 unsigned long val;
146 if (__get_user(val, (unsigned long *)p) == 0)
147 sprintf(str + i * 9, " %08lx", val);
148 else
149 sprintf(str + i * 9, " ????????");
150 }
151 }
152 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
153 }
154
155 set_fs(fs);
156}
157
158static void __dump_instr(const char *lvl, struct pt_regs *regs)
159{
160 unsigned long addr = instruction_pointer(regs);
161 const int thumb = thumb_mode(regs);
162 const int width = thumb ? 4 : 8;
163 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
164 int i;
165
166 /*
167 * Note that we now dump the code first, just in case the backtrace
168 * kills us.
169 */
170
171 for (i = -4; i < 1 + !!thumb; i++) {
172 unsigned int val, bad;
173
174 if (thumb)
175 bad = get_user(val, &((u16 *)addr)[i]);
176 else
177 bad = get_user(val, &((u32 *)addr)[i]);
178
179 if (!bad)
180 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
181 width, val);
182 else {
183 p += sprintf(p, "bad PC value");
184 break;
185 }
186 }
187 printk("%sCode: %s\n", lvl, str);
188}
189
190static void dump_instr(const char *lvl, struct pt_regs *regs)
191{
192 mm_segment_t fs;
193
194 if (!user_mode(regs)) {
195 fs = get_fs();
196 set_fs(KERNEL_DS);
197 __dump_instr(lvl, regs);
198 set_fs(fs);
199 } else {
200 __dump_instr(lvl, regs);
201 }
202}
203
204#ifdef CONFIG_ARM_UNWIND
205static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
206{
207 unwind_backtrace(regs, tsk);
208}
209#else
210static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
211{
212 unsigned int fp, mode;
213 int ok = 1;
214
215 printk("Backtrace: ");
216
217 if (!tsk)
218 tsk = current;
219
220 if (regs) {
221 fp = frame_pointer(regs);
222 mode = processor_mode(regs);
223 } else if (tsk != current) {
224 fp = thread_saved_fp(tsk);
225 mode = 0x10;
226 } else {
227 asm("mov %0, fp" : "=r" (fp) : : "cc");
228 mode = 0x10;
229 }
230
231 if (!fp) {
232 pr_cont("no frame pointer");
233 ok = 0;
234 } else if (verify_stack(fp)) {
235 pr_cont("invalid frame pointer 0x%08x", fp);
236 ok = 0;
237 } else if (fp < (unsigned long)end_of_stack(tsk))
238 pr_cont("frame pointer underflow");
239 pr_cont("\n");
240
241 if (ok)
242 c_backtrace(fp, mode);
243}
244#endif
245
246void show_stack(struct task_struct *tsk, unsigned long *sp)
247{
248 dump_backtrace(NULL, tsk);
249 barrier();
250}
251
252#ifdef CONFIG_PREEMPT
253#define S_PREEMPT " PREEMPT"
254#else
255#define S_PREEMPT ""
256#endif
257#ifdef CONFIG_SMP
258#define S_SMP " SMP"
259#else
260#define S_SMP ""
261#endif
262#ifdef CONFIG_THUMB2_KERNEL
263#define S_ISA " THUMB2"
264#else
265#define S_ISA " ARM"
266#endif
267
268static int __die(const char *str, int err, struct pt_regs *regs)
269{
270 struct task_struct *tsk = current;
271 static int die_counter;
272 int ret;
273
274 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
275 str, err, ++die_counter);
276
277 /* trap and error numbers are mostly meaningless on ARM */
278 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
279 if (ret == NOTIFY_STOP)
280 return 1;
281
282 print_modules();
283 __show_regs(regs);
284 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
285 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
286
287 if (!user_mode(regs) || in_interrupt()) {
288 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
289 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
290 dump_backtrace(regs, tsk);
291 dump_instr(KERN_EMERG, regs);
292 }
293
294 return 0;
295}
296
297static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
298static int die_owner = -1;
299static unsigned int die_nest_count;
300
301static unsigned long oops_begin(void)
302{
303 int cpu;
304 unsigned long flags;
305
306 oops_enter();
307
308 /* racy, but better than risking deadlock. */
309 raw_local_irq_save(flags);
310 cpu = smp_processor_id();
311 if (!arch_spin_trylock(&die_lock)) {
312 if (cpu == die_owner)
313 /* nested oops. should stop eventually */;
314 else
315 arch_spin_lock(&die_lock);
316 }
317 die_nest_count++;
318 die_owner = cpu;
319 console_verbose();
320 bust_spinlocks(1);
321 return flags;
322}
323
324static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
325{
326 if (regs && kexec_should_crash(current))
327 crash_kexec(regs);
328
329 bust_spinlocks(0);
330 die_owner = -1;
331 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
332 die_nest_count--;
333 if (!die_nest_count)
334 /* Nest count reaches zero, release the lock. */
335 arch_spin_unlock(&die_lock);
336 raw_local_irq_restore(flags);
337 oops_exit();
338
339 if (in_interrupt())
340 panic("Fatal exception in interrupt");
341 if (panic_on_oops)
342 panic("Fatal exception");
343 if (signr)
344 do_exit(signr);
345}
346
347/*
348 * This function is protected against re-entrancy.
349 */
350void die(const char *str, struct pt_regs *regs, int err)
351{
352 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
353 unsigned long flags = oops_begin();
354 int sig = SIGSEGV;
355
356 if (!user_mode(regs))
357 bug_type = report_bug(regs->ARM_pc, regs);
358 if (bug_type != BUG_TRAP_TYPE_NONE)
359 str = "Oops - BUG";
360
361 if (__die(str, err, regs))
362 sig = 0;
363
364 oops_end(flags, regs, sig);
365}
366
367void arm_notify_die(const char *str, struct pt_regs *regs,
368 struct siginfo *info, unsigned long err, unsigned long trap)
369{
370 if (user_mode(regs)) {
371 current->thread.error_code = err;
372 current->thread.trap_no = trap;
373
374 force_sig_info(info->si_signo, info, current);
375 } else {
376 die(str, regs, err);
377 }
378}
379
380#ifdef CONFIG_GENERIC_BUG
381
382int is_valid_bugaddr(unsigned long pc)
383{
384#ifdef CONFIG_THUMB2_KERNEL
385 u16 bkpt;
386 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
387#else
388 u32 bkpt;
389 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
390#endif
391
392 if (probe_kernel_address((unsigned *)pc, bkpt))
393 return 0;
394
395 return bkpt == insn;
396}
397
398#endif
399
400static LIST_HEAD(undef_hook);
401static DEFINE_RAW_SPINLOCK(undef_lock);
402
403void register_undef_hook(struct undef_hook *hook)
404{
405 unsigned long flags;
406
407 raw_spin_lock_irqsave(&undef_lock, flags);
408 list_add(&hook->node, &undef_hook);
409 raw_spin_unlock_irqrestore(&undef_lock, flags);
410}
411
412void unregister_undef_hook(struct undef_hook *hook)
413{
414 unsigned long flags;
415
416 raw_spin_lock_irqsave(&undef_lock, flags);
417 list_del(&hook->node);
418 raw_spin_unlock_irqrestore(&undef_lock, flags);
419}
420
421static nokprobe_inline
422int call_undef_hook(struct pt_regs *regs, unsigned int instr)
423{
424 struct undef_hook *hook;
425 unsigned long flags;
426 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
427
428 raw_spin_lock_irqsave(&undef_lock, flags);
429 list_for_each_entry(hook, &undef_hook, node)
430 if ((instr & hook->instr_mask) == hook->instr_val &&
431 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
432 fn = hook->fn;
433 raw_spin_unlock_irqrestore(&undef_lock, flags);
434
435 return fn ? fn(regs, instr) : 1;
436}
437
438asmlinkage void do_undefinstr(struct pt_regs *regs)
439{
440 unsigned int instr;
441 siginfo_t info;
442 void __user *pc;
443
444 pc = (void __user *)instruction_pointer(regs);
445
446 if (processor_mode(regs) == SVC_MODE) {
447#ifdef CONFIG_THUMB2_KERNEL
448 if (thumb_mode(regs)) {
449 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
450 if (is_wide_instruction(instr)) {
451 u16 inst2;
452 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
453 instr = __opcode_thumb32_compose(instr, inst2);
454 }
455 } else
456#endif
457 instr = __mem_to_opcode_arm(*(u32 *) pc);
458 } else if (thumb_mode(regs)) {
459 if (get_user(instr, (u16 __user *)pc))
460 goto die_sig;
461 instr = __mem_to_opcode_thumb16(instr);
462 if (is_wide_instruction(instr)) {
463 unsigned int instr2;
464 if (get_user(instr2, (u16 __user *)pc+1))
465 goto die_sig;
466 instr2 = __mem_to_opcode_thumb16(instr2);
467 instr = __opcode_thumb32_compose(instr, instr2);
468 }
469 } else {
470 if (get_user(instr, (u32 __user *)pc))
471 goto die_sig;
472 instr = __mem_to_opcode_arm(instr);
473 }
474
475 if (call_undef_hook(regs, instr) == 0)
476 return;
477
478die_sig:
479#ifdef CONFIG_DEBUG_USER
480 if (user_debug & UDBG_UNDEFINED) {
481 pr_info("%s (%d): undefined instruction: pc=%p\n",
482 current->comm, task_pid_nr(current), pc);
483 __show_regs(regs);
484 dump_instr(KERN_INFO, regs);
485 }
486#endif
487
488 info.si_signo = SIGILL;
489 info.si_errno = 0;
490 info.si_code = ILL_ILLOPC;
491 info.si_addr = pc;
492
493 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
494}
495NOKPROBE_SYMBOL(do_undefinstr)
496
497/*
498 * Handle FIQ similarly to NMI on x86 systems.
499 *
500 * The runtime environment for NMIs is extremely restrictive
501 * (NMIs can pre-empt critical sections meaning almost all locking is
502 * forbidden) meaning this default FIQ handling must only be used in
503 * circumstances where non-maskability improves robustness, such as
504 * watchdog or debug logic.
505 *
506 * This handler is not appropriate for general purpose use in drivers
507 * platform code and can be overrideen using set_fiq_handler.
508 */
509asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
510{
511 struct pt_regs *old_regs = set_irq_regs(regs);
512
513 nmi_enter();
514
515 /* nop. FIQ handlers for special arch/arm features can be added here. */
516
517 nmi_exit();
518
519 set_irq_regs(old_regs);
520}
521
522/*
523 * bad_mode handles the impossible case in the vectors. If you see one of
524 * these, then it's extremely serious, and could mean you have buggy hardware.
525 * It never returns, and never tries to sync. We hope that we can at least
526 * dump out some state information...
527 */
528asmlinkage void bad_mode(struct pt_regs *regs, int reason)
529{
530 console_verbose();
531
532 pr_crit("Bad mode in %s handler detected\n", handler[reason]);
533
534 die("Oops - bad mode", regs, 0);
535 local_irq_disable();
536 panic("bad mode");
537}
538
539static int bad_syscall(int n, struct pt_regs *regs)
540{
541 siginfo_t info;
542
543 if ((current->personality & PER_MASK) != PER_LINUX) {
544 send_sig(SIGSEGV, current, 1);
545 return regs->ARM_r0;
546 }
547
548#ifdef CONFIG_DEBUG_USER
549 if (user_debug & UDBG_SYSCALL) {
550 pr_err("[%d] %s: obsolete system call %08x.\n",
551 task_pid_nr(current), current->comm, n);
552 dump_instr(KERN_ERR, regs);
553 }
554#endif
555
556 info.si_signo = SIGILL;
557 info.si_errno = 0;
558 info.si_code = ILL_ILLTRP;
559 info.si_addr = (void __user *)instruction_pointer(regs) -
560 (thumb_mode(regs) ? 2 : 4);
561
562 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
563
564 return regs->ARM_r0;
565}
566
567static inline int
568__do_cache_op(unsigned long start, unsigned long end)
569{
570 int ret;
571
572 do {
573 unsigned long chunk = min(PAGE_SIZE, end - start);
574
575 if (fatal_signal_pending(current))
576 return 0;
577
578 ret = flush_cache_user_range(start, start + chunk);
579 if (ret)
580 return ret;
581
582 cond_resched();
583 start += chunk;
584 } while (start < end);
585
586 return 0;
587}
588
589static inline int
590do_cache_op(unsigned long start, unsigned long end, int flags)
591{
592 if (end < start || flags)
593 return -EINVAL;
594
595 if (!access_ok(VERIFY_READ, start, end - start))
596 return -EFAULT;
597
598 return __do_cache_op(start, end);
599}
600
601/*
602 * Handle all unrecognised system calls.
603 * 0x9f0000 - 0x9fffff are some more esoteric system calls
604 */
605#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
606asmlinkage int arm_syscall(int no, struct pt_regs *regs)
607{
608 siginfo_t info;
609
610 if ((no >> 16) != (__ARM_NR_BASE>> 16))
611 return bad_syscall(no, regs);
612
613 switch (no & 0xffff) {
614 case 0: /* branch through 0 */
615 info.si_signo = SIGSEGV;
616 info.si_errno = 0;
617 info.si_code = SEGV_MAPERR;
618 info.si_addr = NULL;
619
620 arm_notify_die("branch through zero", regs, &info, 0, 0);
621 return 0;
622
623 case NR(breakpoint): /* SWI BREAK_POINT */
624 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
625 ptrace_break(current, regs);
626 return regs->ARM_r0;
627
628 /*
629 * Flush a region from virtual address 'r0' to virtual address 'r1'
630 * _exclusive_. There is no alignment requirement on either address;
631 * user space does not need to know the hardware cache layout.
632 *
633 * r2 contains flags. It should ALWAYS be passed as ZERO until it
634 * is defined to be something else. For now we ignore it, but may
635 * the fires of hell burn in your belly if you break this rule. ;)
636 *
637 * (at a later date, we may want to allow this call to not flush
638 * various aspects of the cache. Passing '0' will guarantee that
639 * everything necessary gets flushed to maintain consistency in
640 * the specified region).
641 */
642 case NR(cacheflush):
643 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
644
645 case NR(usr26):
646 if (!(elf_hwcap & HWCAP_26BIT))
647 break;
648 regs->ARM_cpsr &= ~MODE32_BIT;
649 return regs->ARM_r0;
650
651 case NR(usr32):
652 if (!(elf_hwcap & HWCAP_26BIT))
653 break;
654 regs->ARM_cpsr |= MODE32_BIT;
655 return regs->ARM_r0;
656
657 case NR(set_tls):
658 set_tls(regs->ARM_r0);
659 return 0;
660
661 case NR(get_tls):
662 return current_thread_info()->tp_value[0];
663
664 default:
665 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
666 if not implemented, rather than raising SIGILL. This
667 way the calling program can gracefully determine whether
668 a feature is supported. */
669 if ((no & 0xffff) <= 0x7ff)
670 return -ENOSYS;
671 break;
672 }
673#ifdef CONFIG_DEBUG_USER
674 /*
675 * experience shows that these seem to indicate that
676 * something catastrophic has happened
677 */
678 if (user_debug & UDBG_SYSCALL) {
679 pr_err("[%d] %s: arm syscall %d\n",
680 task_pid_nr(current), current->comm, no);
681 dump_instr("", regs);
682 if (user_mode(regs)) {
683 __show_regs(regs);
684 c_backtrace(frame_pointer(regs), processor_mode(regs));
685 }
686 }
687#endif
688 info.si_signo = SIGILL;
689 info.si_errno = 0;
690 info.si_code = ILL_ILLTRP;
691 info.si_addr = (void __user *)instruction_pointer(regs) -
692 (thumb_mode(regs) ? 2 : 4);
693
694 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
695 return 0;
696}
697
698#ifdef CONFIG_TLS_REG_EMUL
699
700/*
701 * We might be running on an ARMv6+ processor which should have the TLS
702 * register but for some reason we can't use it, or maybe an SMP system
703 * using a pre-ARMv6 processor (there are apparently a few prototypes like
704 * that in existence) and therefore access to that register must be
705 * emulated.
706 */
707
708static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
709{
710 int reg = (instr >> 12) & 15;
711 if (reg == 15)
712 return 1;
713 regs->uregs[reg] = current_thread_info()->tp_value[0];
714 regs->ARM_pc += 4;
715 return 0;
716}
717
718static struct undef_hook arm_mrc_hook = {
719 .instr_mask = 0x0fff0fff,
720 .instr_val = 0x0e1d0f70,
721 .cpsr_mask = PSR_T_BIT,
722 .cpsr_val = 0,
723 .fn = get_tp_trap,
724};
725
726static int __init arm_mrc_hook_init(void)
727{
728 register_undef_hook(&arm_mrc_hook);
729 return 0;
730}
731
732late_initcall(arm_mrc_hook_init);
733
734#endif
735
736/*
737 * A data abort trap was taken, but we did not handle the instruction.
738 * Try to abort the user program, or panic if it was the kernel.
739 */
740asmlinkage void
741baddataabort(int code, unsigned long instr, struct pt_regs *regs)
742{
743 unsigned long addr = instruction_pointer(regs);
744 siginfo_t info;
745
746#ifdef CONFIG_DEBUG_USER
747 if (user_debug & UDBG_BADABORT) {
748 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
749 task_pid_nr(current), current->comm, code, instr);
750 dump_instr(KERN_ERR, regs);
751 show_pte(current->mm, addr);
752 }
753#endif
754
755 info.si_signo = SIGILL;
756 info.si_errno = 0;
757 info.si_code = ILL_ILLOPC;
758 info.si_addr = (void __user *)addr;
759
760 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
761}
762
763void __readwrite_bug(const char *fn)
764{
765 pr_err("%s called, but not implemented\n", fn);
766 BUG();
767}
768EXPORT_SYMBOL(__readwrite_bug);
769
770void __pte_error(const char *file, int line, pte_t pte)
771{
772 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
773}
774
775void __pmd_error(const char *file, int line, pmd_t pmd)
776{
777 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
778}
779
780void __pgd_error(const char *file, int line, pgd_t pgd)
781{
782 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
783}
784
785asmlinkage void __div0(void)
786{
787 pr_err("Division by zero in kernel.\n");
788 dump_stack();
789}
790EXPORT_SYMBOL(__div0);
791
792void abort(void)
793{
794 BUG();
795
796 /* if that doesn't kill us, halt */
797 panic("Oops failed to kill thread");
798}
799
800void __init trap_init(void)
801{
802 return;
803}
804
805#ifdef CONFIG_KUSER_HELPERS
806static void __init kuser_init(void *vectors)
807{
808 extern char __kuser_helper_start[], __kuser_helper_end[];
809 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
810
811 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
812
813 /*
814 * vectors + 0xfe0 = __kuser_get_tls
815 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
816 */
817 if (tls_emu || has_tls_reg)
818 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
819}
820#else
821static inline void __init kuser_init(void *vectors)
822{
823}
824#endif
825
826void __init early_trap_init(void *vectors_base)
827{
828#ifndef CONFIG_CPU_V7M
829 unsigned long vectors = (unsigned long)vectors_base;
830 extern char __stubs_start[], __stubs_end[];
831 extern char __vectors_start[], __vectors_end[];
832 unsigned i;
833
834 vectors_page = vectors_base;
835
836 /*
837 * Poison the vectors page with an undefined instruction. This
838 * instruction is chosen to be undefined for both ARM and Thumb
839 * ISAs. The Thumb version is an undefined instruction with a
840 * branch back to the undefined instruction.
841 */
842 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
843 ((u32 *)vectors_base)[i] = 0xe7fddef1;
844
845 /*
846 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
847 * into the vector page, mapped at 0xffff0000, and ensure these
848 * are visible to the instruction stream.
849 */
850 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
851 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
852
853 kuser_init(vectors_base);
854
855 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
856#else /* ifndef CONFIG_CPU_V7M */
857 /*
858 * on V7-M there is no need to copy the vector table to a dedicated
859 * memory area. The address is configurable and so a table in the kernel
860 * image can be used.
861 */
862#endif
863}