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