Loading...
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/delay.h>
25#include <linux/init.h>
26#include <linux/sched.h>
27
28#include <linux/atomic.h>
29#include <asm/cacheflush.h>
30#include <asm/system.h>
31#include <asm/unistd.h>
32#include <asm/traps.h>
33#include <asm/unwind.h>
34#include <asm/tls.h>
35
36#include "signal.h"
37
38static const char *handler[]= { "prefetch abort", "data abort", "address exception", "interrupt" };
39
40void *vectors_page;
41
42#ifdef CONFIG_DEBUG_USER
43unsigned int user_debug;
44
45static int __init user_debug_setup(char *str)
46{
47 get_option(&str, &user_debug);
48 return 1;
49}
50__setup("user_debug=", user_debug_setup);
51#endif
52
53static void dump_mem(const char *, const char *, unsigned long, unsigned long);
54
55void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
56{
57#ifdef CONFIG_KALLSYMS
58 printk("[<%08lx>] (%pS) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
59#else
60 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
61#endif
62
63 if (in_exception_text(where))
64 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
65}
66
67#ifndef CONFIG_ARM_UNWIND
68/*
69 * Stack pointers should always be within the kernels view of
70 * physical memory. If it is not there, then we can't dump
71 * out any information relating to the stack.
72 */
73static int verify_stack(unsigned long sp)
74{
75 if (sp < PAGE_OFFSET ||
76 (sp > (unsigned long)high_memory && high_memory != NULL))
77 return -EFAULT;
78
79 return 0;
80}
81#endif
82
83/*
84 * Dump out the contents of some memory nicely...
85 */
86static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
87 unsigned long top)
88{
89 unsigned long first;
90 mm_segment_t fs;
91 int i;
92
93 /*
94 * We need to switch to kernel mode so that we can use __get_user
95 * to safely read from kernel space. Note that we now dump the
96 * code first, just in case the backtrace kills us.
97 */
98 fs = get_fs();
99 set_fs(KERNEL_DS);
100
101 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
102
103 for (first = bottom & ~31; first < top; first += 32) {
104 unsigned long p;
105 char str[sizeof(" 12345678") * 8 + 1];
106
107 memset(str, ' ', sizeof(str));
108 str[sizeof(str) - 1] = '\0';
109
110 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
111 if (p >= bottom && p < top) {
112 unsigned long val;
113 if (__get_user(val, (unsigned long *)p) == 0)
114 sprintf(str + i * 9, " %08lx", val);
115 else
116 sprintf(str + i * 9, " ????????");
117 }
118 }
119 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
120 }
121
122 set_fs(fs);
123}
124
125static void dump_instr(const char *lvl, struct pt_regs *regs)
126{
127 unsigned long addr = instruction_pointer(regs);
128 const int thumb = thumb_mode(regs);
129 const int width = thumb ? 4 : 8;
130 mm_segment_t fs;
131 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
132 int i;
133
134 /*
135 * We need to switch to kernel mode so that we can use __get_user
136 * to safely read from kernel space. Note that we now dump the
137 * code first, just in case the backtrace kills us.
138 */
139 fs = get_fs();
140 set_fs(KERNEL_DS);
141
142 for (i = -4; i < 1 + !!thumb; i++) {
143 unsigned int val, bad;
144
145 if (thumb)
146 bad = __get_user(val, &((u16 *)addr)[i]);
147 else
148 bad = __get_user(val, &((u32 *)addr)[i]);
149
150 if (!bad)
151 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
152 width, val);
153 else {
154 p += sprintf(p, "bad PC value");
155 break;
156 }
157 }
158 printk("%sCode: %s\n", lvl, str);
159
160 set_fs(fs);
161}
162
163#ifdef CONFIG_ARM_UNWIND
164static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
165{
166 unwind_backtrace(regs, tsk);
167}
168#else
169static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
170{
171 unsigned int fp, mode;
172 int ok = 1;
173
174 printk("Backtrace: ");
175
176 if (!tsk)
177 tsk = current;
178
179 if (regs) {
180 fp = regs->ARM_fp;
181 mode = processor_mode(regs);
182 } else if (tsk != current) {
183 fp = thread_saved_fp(tsk);
184 mode = 0x10;
185 } else {
186 asm("mov %0, fp" : "=r" (fp) : : "cc");
187 mode = 0x10;
188 }
189
190 if (!fp) {
191 printk("no frame pointer");
192 ok = 0;
193 } else if (verify_stack(fp)) {
194 printk("invalid frame pointer 0x%08x", fp);
195 ok = 0;
196 } else if (fp < (unsigned long)end_of_stack(tsk))
197 printk("frame pointer underflow");
198 printk("\n");
199
200 if (ok)
201 c_backtrace(fp, mode);
202}
203#endif
204
205void dump_stack(void)
206{
207 dump_backtrace(NULL, NULL);
208}
209
210EXPORT_SYMBOL(dump_stack);
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
229static int __die(const char *str, int err, struct thread_info *thread, struct pt_regs *regs)
230{
231 struct task_struct *tsk = thread->task;
232 static int die_counter;
233 int ret;
234
235 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
236 str, err, ++die_counter);
237
238 /* trap and error numbers are mostly meaningless on ARM */
239 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
240 if (ret == NOTIFY_STOP)
241 return ret;
242
243 print_modules();
244 __show_regs(regs);
245 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
246 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
247
248 if (!user_mode(regs) || in_interrupt()) {
249 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
250 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
251 dump_backtrace(regs, tsk);
252 dump_instr(KERN_EMERG, regs);
253 }
254
255 return ret;
256}
257
258static DEFINE_SPINLOCK(die_lock);
259
260/*
261 * This function is protected against re-entrancy.
262 */
263void die(const char *str, struct pt_regs *regs, int err)
264{
265 struct thread_info *thread = current_thread_info();
266 int ret;
267
268 oops_enter();
269
270 spin_lock_irq(&die_lock);
271 console_verbose();
272 bust_spinlocks(1);
273 ret = __die(str, err, thread, regs);
274
275 if (regs && kexec_should_crash(thread->task))
276 crash_kexec(regs);
277
278 bust_spinlocks(0);
279 add_taint(TAINT_DIE);
280 spin_unlock_irq(&die_lock);
281 oops_exit();
282
283 if (in_interrupt())
284 panic("Fatal exception in interrupt");
285 if (panic_on_oops)
286 panic("Fatal exception");
287 if (ret != NOTIFY_STOP)
288 do_exit(SIGSEGV);
289}
290
291void arm_notify_die(const char *str, struct pt_regs *regs,
292 struct siginfo *info, unsigned long err, unsigned long trap)
293{
294 if (user_mode(regs)) {
295 current->thread.error_code = err;
296 current->thread.trap_no = trap;
297
298 force_sig_info(info->si_signo, info, current);
299 } else {
300 die(str, regs, err);
301 }
302}
303
304static LIST_HEAD(undef_hook);
305static DEFINE_SPINLOCK(undef_lock);
306
307void register_undef_hook(struct undef_hook *hook)
308{
309 unsigned long flags;
310
311 spin_lock_irqsave(&undef_lock, flags);
312 list_add(&hook->node, &undef_hook);
313 spin_unlock_irqrestore(&undef_lock, flags);
314}
315
316void unregister_undef_hook(struct undef_hook *hook)
317{
318 unsigned long flags;
319
320 spin_lock_irqsave(&undef_lock, flags);
321 list_del(&hook->node);
322 spin_unlock_irqrestore(&undef_lock, flags);
323}
324
325static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
326{
327 struct undef_hook *hook;
328 unsigned long flags;
329 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
330
331 spin_lock_irqsave(&undef_lock, flags);
332 list_for_each_entry(hook, &undef_hook, node)
333 if ((instr & hook->instr_mask) == hook->instr_val &&
334 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
335 fn = hook->fn;
336 spin_unlock_irqrestore(&undef_lock, flags);
337
338 return fn ? fn(regs, instr) : 1;
339}
340
341asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
342{
343 unsigned int correction = thumb_mode(regs) ? 2 : 4;
344 unsigned int instr;
345 siginfo_t info;
346 void __user *pc;
347
348 /*
349 * According to the ARM ARM, PC is 2 or 4 bytes ahead,
350 * depending whether we're in Thumb mode or not.
351 * Correct this offset.
352 */
353 regs->ARM_pc -= correction;
354
355 pc = (void __user *)instruction_pointer(regs);
356
357 if (processor_mode(regs) == SVC_MODE) {
358#ifdef CONFIG_THUMB2_KERNEL
359 if (thumb_mode(regs)) {
360 instr = ((u16 *)pc)[0];
361 if (is_wide_instruction(instr)) {
362 instr <<= 16;
363 instr |= ((u16 *)pc)[1];
364 }
365 } else
366#endif
367 instr = *(u32 *) pc;
368 } else if (thumb_mode(regs)) {
369 get_user(instr, (u16 __user *)pc);
370 if (is_wide_instruction(instr)) {
371 unsigned int instr2;
372 get_user(instr2, (u16 __user *)pc+1);
373 instr <<= 16;
374 instr |= instr2;
375 }
376 } else {
377 get_user(instr, (u32 __user *)pc);
378 }
379
380 if (call_undef_hook(regs, instr) == 0)
381 return;
382
383#ifdef CONFIG_DEBUG_USER
384 if (user_debug & UDBG_UNDEFINED) {
385 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
386 current->comm, task_pid_nr(current), pc);
387 dump_instr(KERN_INFO, regs);
388 }
389#endif
390
391 info.si_signo = SIGILL;
392 info.si_errno = 0;
393 info.si_code = ILL_ILLOPC;
394 info.si_addr = pc;
395
396 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
397}
398
399asmlinkage void do_unexp_fiq (struct pt_regs *regs)
400{
401 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
402 printk("You may have a hardware problem...\n");
403}
404
405/*
406 * bad_mode handles the impossible case in the vectors. If you see one of
407 * these, then it's extremely serious, and could mean you have buggy hardware.
408 * It never returns, and never tries to sync. We hope that we can at least
409 * dump out some state information...
410 */
411asmlinkage void bad_mode(struct pt_regs *regs, int reason)
412{
413 console_verbose();
414
415 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
416
417 die("Oops - bad mode", regs, 0);
418 local_irq_disable();
419 panic("bad mode");
420}
421
422static int bad_syscall(int n, struct pt_regs *regs)
423{
424 struct thread_info *thread = current_thread_info();
425 siginfo_t info;
426
427 if ((current->personality & PER_MASK) != PER_LINUX &&
428 thread->exec_domain->handler) {
429 thread->exec_domain->handler(n, regs);
430 return regs->ARM_r0;
431 }
432
433#ifdef CONFIG_DEBUG_USER
434 if (user_debug & UDBG_SYSCALL) {
435 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
436 task_pid_nr(current), current->comm, n);
437 dump_instr(KERN_ERR, regs);
438 }
439#endif
440
441 info.si_signo = SIGILL;
442 info.si_errno = 0;
443 info.si_code = ILL_ILLTRP;
444 info.si_addr = (void __user *)instruction_pointer(regs) -
445 (thumb_mode(regs) ? 2 : 4);
446
447 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
448
449 return regs->ARM_r0;
450}
451
452static inline void
453do_cache_op(unsigned long start, unsigned long end, int flags)
454{
455 struct mm_struct *mm = current->active_mm;
456 struct vm_area_struct *vma;
457
458 if (end < start || flags)
459 return;
460
461 down_read(&mm->mmap_sem);
462 vma = find_vma(mm, start);
463 if (vma && vma->vm_start < end) {
464 if (start < vma->vm_start)
465 start = vma->vm_start;
466 if (end > vma->vm_end)
467 end = vma->vm_end;
468
469 flush_cache_user_range(vma, start, end);
470 }
471 up_read(&mm->mmap_sem);
472}
473
474/*
475 * Handle all unrecognised system calls.
476 * 0x9f0000 - 0x9fffff are some more esoteric system calls
477 */
478#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
479asmlinkage int arm_syscall(int no, struct pt_regs *regs)
480{
481 struct thread_info *thread = current_thread_info();
482 siginfo_t info;
483
484 if ((no >> 16) != (__ARM_NR_BASE>> 16))
485 return bad_syscall(no, regs);
486
487 switch (no & 0xffff) {
488 case 0: /* branch through 0 */
489 info.si_signo = SIGSEGV;
490 info.si_errno = 0;
491 info.si_code = SEGV_MAPERR;
492 info.si_addr = NULL;
493
494 arm_notify_die("branch through zero", regs, &info, 0, 0);
495 return 0;
496
497 case NR(breakpoint): /* SWI BREAK_POINT */
498 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
499 ptrace_break(current, regs);
500 return regs->ARM_r0;
501
502 /*
503 * Flush a region from virtual address 'r0' to virtual address 'r1'
504 * _exclusive_. There is no alignment requirement on either address;
505 * user space does not need to know the hardware cache layout.
506 *
507 * r2 contains flags. It should ALWAYS be passed as ZERO until it
508 * is defined to be something else. For now we ignore it, but may
509 * the fires of hell burn in your belly if you break this rule. ;)
510 *
511 * (at a later date, we may want to allow this call to not flush
512 * various aspects of the cache. Passing '0' will guarantee that
513 * everything necessary gets flushed to maintain consistency in
514 * the specified region).
515 */
516 case NR(cacheflush):
517 do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
518 return 0;
519
520 case NR(usr26):
521 if (!(elf_hwcap & HWCAP_26BIT))
522 break;
523 regs->ARM_cpsr &= ~MODE32_BIT;
524 return regs->ARM_r0;
525
526 case NR(usr32):
527 if (!(elf_hwcap & HWCAP_26BIT))
528 break;
529 regs->ARM_cpsr |= MODE32_BIT;
530 return regs->ARM_r0;
531
532 case NR(set_tls):
533 thread->tp_value = regs->ARM_r0;
534 if (tls_emu)
535 return 0;
536 if (has_tls_reg) {
537 asm ("mcr p15, 0, %0, c13, c0, 3"
538 : : "r" (regs->ARM_r0));
539 } else {
540 /*
541 * User space must never try to access this directly.
542 * Expect your app to break eventually if you do so.
543 * The user helper at 0xffff0fe0 must be used instead.
544 * (see entry-armv.S for details)
545 */
546 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
547 }
548 return 0;
549
550#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
551 /*
552 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
553 * Return zero in r0 if *MEM was changed or non-zero if no exchange
554 * happened. Also set the user C flag accordingly.
555 * If access permissions have to be fixed up then non-zero is
556 * returned and the operation has to be re-attempted.
557 *
558 * *NOTE*: This is a ghost syscall private to the kernel. Only the
559 * __kuser_cmpxchg code in entry-armv.S should be aware of its
560 * existence. Don't ever use this from user code.
561 */
562 case NR(cmpxchg):
563 for (;;) {
564 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
565 struct pt_regs *regs);
566 unsigned long val;
567 unsigned long addr = regs->ARM_r2;
568 struct mm_struct *mm = current->mm;
569 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
570 spinlock_t *ptl;
571
572 regs->ARM_cpsr &= ~PSR_C_BIT;
573 down_read(&mm->mmap_sem);
574 pgd = pgd_offset(mm, addr);
575 if (!pgd_present(*pgd))
576 goto bad_access;
577 pmd = pmd_offset(pgd, addr);
578 if (!pmd_present(*pmd))
579 goto bad_access;
580 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
581 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
582 pte_unmap_unlock(pte, ptl);
583 goto bad_access;
584 }
585 val = *(unsigned long *)addr;
586 val -= regs->ARM_r0;
587 if (val == 0) {
588 *(unsigned long *)addr = regs->ARM_r1;
589 regs->ARM_cpsr |= PSR_C_BIT;
590 }
591 pte_unmap_unlock(pte, ptl);
592 up_read(&mm->mmap_sem);
593 return val;
594
595 bad_access:
596 up_read(&mm->mmap_sem);
597 /* simulate a write access fault */
598 do_DataAbort(addr, 15 + (1 << 11), regs);
599 }
600#endif
601
602 default:
603 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
604 if not implemented, rather than raising SIGILL. This
605 way the calling program can gracefully determine whether
606 a feature is supported. */
607 if ((no & 0xffff) <= 0x7ff)
608 return -ENOSYS;
609 break;
610 }
611#ifdef CONFIG_DEBUG_USER
612 /*
613 * experience shows that these seem to indicate that
614 * something catastrophic has happened
615 */
616 if (user_debug & UDBG_SYSCALL) {
617 printk("[%d] %s: arm syscall %d\n",
618 task_pid_nr(current), current->comm, no);
619 dump_instr("", regs);
620 if (user_mode(regs)) {
621 __show_regs(regs);
622 c_backtrace(regs->ARM_fp, processor_mode(regs));
623 }
624 }
625#endif
626 info.si_signo = SIGILL;
627 info.si_errno = 0;
628 info.si_code = ILL_ILLTRP;
629 info.si_addr = (void __user *)instruction_pointer(regs) -
630 (thumb_mode(regs) ? 2 : 4);
631
632 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
633 return 0;
634}
635
636#ifdef CONFIG_TLS_REG_EMUL
637
638/*
639 * We might be running on an ARMv6+ processor which should have the TLS
640 * register but for some reason we can't use it, or maybe an SMP system
641 * using a pre-ARMv6 processor (there are apparently a few prototypes like
642 * that in existence) and therefore access to that register must be
643 * emulated.
644 */
645
646static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
647{
648 int reg = (instr >> 12) & 15;
649 if (reg == 15)
650 return 1;
651 regs->uregs[reg] = current_thread_info()->tp_value;
652 regs->ARM_pc += 4;
653 return 0;
654}
655
656static struct undef_hook arm_mrc_hook = {
657 .instr_mask = 0x0fff0fff,
658 .instr_val = 0x0e1d0f70,
659 .cpsr_mask = PSR_T_BIT,
660 .cpsr_val = 0,
661 .fn = get_tp_trap,
662};
663
664static int __init arm_mrc_hook_init(void)
665{
666 register_undef_hook(&arm_mrc_hook);
667 return 0;
668}
669
670late_initcall(arm_mrc_hook_init);
671
672#endif
673
674void __bad_xchg(volatile void *ptr, int size)
675{
676 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
677 __builtin_return_address(0), ptr, size);
678 BUG();
679}
680EXPORT_SYMBOL(__bad_xchg);
681
682/*
683 * A data abort trap was taken, but we did not handle the instruction.
684 * Try to abort the user program, or panic if it was the kernel.
685 */
686asmlinkage void
687baddataabort(int code, unsigned long instr, struct pt_regs *regs)
688{
689 unsigned long addr = instruction_pointer(regs);
690 siginfo_t info;
691
692#ifdef CONFIG_DEBUG_USER
693 if (user_debug & UDBG_BADABORT) {
694 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
695 task_pid_nr(current), current->comm, code, instr);
696 dump_instr(KERN_ERR, regs);
697 show_pte(current->mm, addr);
698 }
699#endif
700
701 info.si_signo = SIGILL;
702 info.si_errno = 0;
703 info.si_code = ILL_ILLOPC;
704 info.si_addr = (void __user *)addr;
705
706 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
707}
708
709void __attribute__((noreturn)) __bug(const char *file, int line)
710{
711 printk(KERN_CRIT"kernel BUG at %s:%d!\n", file, line);
712 *(int *)0 = 0;
713
714 /* Avoid "noreturn function does return" */
715 for (;;);
716}
717EXPORT_SYMBOL(__bug);
718
719void __readwrite_bug(const char *fn)
720{
721 printk("%s called, but not implemented\n", fn);
722 BUG();
723}
724EXPORT_SYMBOL(__readwrite_bug);
725
726void __pte_error(const char *file, int line, pte_t pte)
727{
728 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
729}
730
731void __pmd_error(const char *file, int line, pmd_t pmd)
732{
733 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
734}
735
736void __pgd_error(const char *file, int line, pgd_t pgd)
737{
738 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
739}
740
741asmlinkage void __div0(void)
742{
743 printk("Division by zero in kernel.\n");
744 dump_stack();
745}
746EXPORT_SYMBOL(__div0);
747
748void abort(void)
749{
750 BUG();
751
752 /* if that doesn't kill us, halt */
753 panic("Oops failed to kill thread");
754}
755EXPORT_SYMBOL(abort);
756
757void __init trap_init(void)
758{
759 return;
760}
761
762static void __init kuser_get_tls_init(unsigned long vectors)
763{
764 /*
765 * vectors + 0xfe0 = __kuser_get_tls
766 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
767 */
768 if (tls_emu || has_tls_reg)
769 memcpy((void *)vectors + 0xfe0, (void *)vectors + 0xfe8, 4);
770}
771
772void __init early_trap_init(void)
773{
774#if defined(CONFIG_CPU_USE_DOMAINS)
775 unsigned long vectors = CONFIG_VECTORS_BASE;
776#else
777 unsigned long vectors = (unsigned long)vectors_page;
778#endif
779 extern char __stubs_start[], __stubs_end[];
780 extern char __vectors_start[], __vectors_end[];
781 extern char __kuser_helper_start[], __kuser_helper_end[];
782 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
783
784 /*
785 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
786 * into the vector page, mapped at 0xffff0000, and ensure these
787 * are visible to the instruction stream.
788 */
789 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
790 memcpy((void *)vectors + 0x200, __stubs_start, __stubs_end - __stubs_start);
791 memcpy((void *)vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
792
793 /*
794 * Do processor specific fixups for the kuser helpers
795 */
796 kuser_get_tls_init(vectors);
797
798 /*
799 * Copy signal return handlers into the vector page, and
800 * set sigreturn to be a pointer to these.
801 */
802 memcpy((void *)(vectors + KERN_SIGRETURN_CODE - CONFIG_VECTORS_BASE),
803 sigreturn_codes, sizeof(sigreturn_codes));
804 memcpy((void *)(vectors + KERN_RESTART_CODE - CONFIG_VECTORS_BASE),
805 syscall_restart_code, sizeof(syscall_restart_code));
806
807 flush_icache_range(vectors, vectors + PAGE_SIZE);
808 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
809}
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}