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