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/bug.h>
25#include <linux/delay.h>
26#include <linux/init.h>
27#include <linux/sched.h>
28
29#include <linux/atomic.h>
30#include <asm/cacheflush.h>
31#include <asm/exception.h>
32#include <asm/unistd.h>
33#include <asm/traps.h>
34#include <asm/unwind.h>
35#include <asm/tls.h>
36#include <asm/system_misc.h>
37#include <asm/opcodes.h>
38
39static const char *handler[]= {
40 "prefetch abort",
41 "data abort",
42 "address exception",
43 "interrupt",
44 "undefined instruction",
45};
46
47void *vectors_page;
48
49#ifdef CONFIG_DEBUG_USER
50unsigned int user_debug;
51
52static int __init user_debug_setup(char *str)
53{
54 get_option(&str, &user_debug);
55 return 1;
56}
57__setup("user_debug=", user_debug_setup);
58#endif
59
60static void dump_mem(const char *, const char *, unsigned long, unsigned long);
61
62void dump_backtrace_entry(unsigned long where, unsigned long from, unsigned long frame)
63{
64#ifdef CONFIG_KALLSYMS
65 printk("[<%08lx>] (%ps) from [<%08lx>] (%pS)\n", where, (void *)where, from, (void *)from);
66#else
67 printk("Function entered at [<%08lx>] from [<%08lx>]\n", where, from);
68#endif
69
70 if (in_exception_text(where))
71 dump_mem("", "Exception stack", frame + 4, frame + 4 + sizeof(struct pt_regs));
72}
73
74#ifndef CONFIG_ARM_UNWIND
75/*
76 * Stack pointers should always be within the kernels view of
77 * physical memory. If it is not there, then we can't dump
78 * out any information relating to the stack.
79 */
80static int verify_stack(unsigned long sp)
81{
82 if (sp < PAGE_OFFSET ||
83 (sp > (unsigned long)high_memory && high_memory != NULL))
84 return -EFAULT;
85
86 return 0;
87}
88#endif
89
90/*
91 * Dump out the contents of some memory nicely...
92 */
93static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
94 unsigned long top)
95{
96 unsigned long first;
97 mm_segment_t fs;
98 int i;
99
100 /*
101 * We need to switch to kernel mode so that we can use __get_user
102 * to safely read from kernel space. Note that we now dump the
103 * code first, just in case the backtrace kills us.
104 */
105 fs = get_fs();
106 set_fs(KERNEL_DS);
107
108 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
109
110 for (first = bottom & ~31; first < top; first += 32) {
111 unsigned long p;
112 char str[sizeof(" 12345678") * 8 + 1];
113
114 memset(str, ' ', sizeof(str));
115 str[sizeof(str) - 1] = '\0';
116
117 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
118 if (p >= bottom && p < top) {
119 unsigned long val;
120 if (__get_user(val, (unsigned long *)p) == 0)
121 sprintf(str + i * 9, " %08lx", val);
122 else
123 sprintf(str + i * 9, " ????????");
124 }
125 }
126 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
127 }
128
129 set_fs(fs);
130}
131
132static void dump_instr(const char *lvl, struct pt_regs *regs)
133{
134 unsigned long addr = instruction_pointer(regs);
135 const int thumb = thumb_mode(regs);
136 const int width = thumb ? 4 : 8;
137 mm_segment_t fs;
138 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
139 int i;
140
141 /*
142 * We need to switch to kernel mode so that we can use __get_user
143 * to safely read from kernel space. Note that we now dump the
144 * code first, just in case the backtrace kills us.
145 */
146 fs = get_fs();
147 set_fs(KERNEL_DS);
148
149 for (i = -4; i < 1 + !!thumb; i++) {
150 unsigned int val, bad;
151
152 if (thumb)
153 bad = __get_user(val, &((u16 *)addr)[i]);
154 else
155 bad = __get_user(val, &((u32 *)addr)[i]);
156
157 if (!bad)
158 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
159 width, val);
160 else {
161 p += sprintf(p, "bad PC value");
162 break;
163 }
164 }
165 printk("%sCode: %s\n", lvl, str);
166
167 set_fs(fs);
168}
169
170#ifdef CONFIG_ARM_UNWIND
171static inline void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
172{
173 unwind_backtrace(regs, tsk);
174}
175#else
176static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
177{
178 unsigned int fp, mode;
179 int ok = 1;
180
181 printk("Backtrace: ");
182
183 if (!tsk)
184 tsk = current;
185
186 if (regs) {
187 fp = regs->ARM_fp;
188 mode = processor_mode(regs);
189 } else if (tsk != current) {
190 fp = thread_saved_fp(tsk);
191 mode = 0x10;
192 } else {
193 asm("mov %0, fp" : "=r" (fp) : : "cc");
194 mode = 0x10;
195 }
196
197 if (!fp) {
198 printk("no frame pointer");
199 ok = 0;
200 } else if (verify_stack(fp)) {
201 printk("invalid frame pointer 0x%08x", fp);
202 ok = 0;
203 } else if (fp < (unsigned long)end_of_stack(tsk))
204 printk("frame pointer underflow");
205 printk("\n");
206
207 if (ok)
208 c_backtrace(fp, mode);
209}
210#endif
211
212void show_stack(struct task_struct *tsk, unsigned long *sp)
213{
214 dump_backtrace(NULL, tsk);
215 barrier();
216}
217
218#ifdef CONFIG_PREEMPT
219#define S_PREEMPT " PREEMPT"
220#else
221#define S_PREEMPT ""
222#endif
223#ifdef CONFIG_SMP
224#define S_SMP " SMP"
225#else
226#define S_SMP ""
227#endif
228#ifdef CONFIG_THUMB2_KERNEL
229#define S_ISA " THUMB2"
230#else
231#define S_ISA " ARM"
232#endif
233
234static int __die(const char *str, int err, struct pt_regs *regs)
235{
236 struct task_struct *tsk = current;
237 static int die_counter;
238 int ret;
239
240 printk(KERN_EMERG "Internal error: %s: %x [#%d]" S_PREEMPT S_SMP
241 S_ISA "\n", str, err, ++die_counter);
242
243 /* trap and error numbers are mostly meaningless on ARM */
244 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
245 if (ret == NOTIFY_STOP)
246 return 1;
247
248 print_modules();
249 __show_regs(regs);
250 printk(KERN_EMERG "Process %.*s (pid: %d, stack limit = 0x%p)\n",
251 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
252
253 if (!user_mode(regs) || in_interrupt()) {
254 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
255 THREAD_SIZE + (unsigned long)task_stack_page(tsk));
256 dump_backtrace(regs, tsk);
257 dump_instr(KERN_EMERG, regs);
258 }
259
260 return 0;
261}
262
263static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
264static int die_owner = -1;
265static unsigned int die_nest_count;
266
267static unsigned long oops_begin(void)
268{
269 int cpu;
270 unsigned long flags;
271
272 oops_enter();
273
274 /* racy, but better than risking deadlock. */
275 raw_local_irq_save(flags);
276 cpu = smp_processor_id();
277 if (!arch_spin_trylock(&die_lock)) {
278 if (cpu == die_owner)
279 /* nested oops. should stop eventually */;
280 else
281 arch_spin_lock(&die_lock);
282 }
283 die_nest_count++;
284 die_owner = cpu;
285 console_verbose();
286 bust_spinlocks(1);
287 return flags;
288}
289
290static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
291{
292 if (regs && kexec_should_crash(current))
293 crash_kexec(regs);
294
295 bust_spinlocks(0);
296 die_owner = -1;
297 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
298 die_nest_count--;
299 if (!die_nest_count)
300 /* Nest count reaches zero, release the lock. */
301 arch_spin_unlock(&die_lock);
302 raw_local_irq_restore(flags);
303 oops_exit();
304
305 if (in_interrupt())
306 panic("Fatal exception in interrupt");
307 if (panic_on_oops)
308 panic("Fatal exception");
309 if (signr)
310 do_exit(signr);
311}
312
313/*
314 * This function is protected against re-entrancy.
315 */
316void die(const char *str, struct pt_regs *regs, int err)
317{
318 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
319 unsigned long flags = oops_begin();
320 int sig = SIGSEGV;
321
322 if (!user_mode(regs))
323 bug_type = report_bug(regs->ARM_pc, regs);
324 if (bug_type != BUG_TRAP_TYPE_NONE)
325 str = "Oops - BUG";
326
327 if (__die(str, err, regs))
328 sig = 0;
329
330 oops_end(flags, regs, sig);
331}
332
333void arm_notify_die(const char *str, struct pt_regs *regs,
334 struct siginfo *info, unsigned long err, unsigned long trap)
335{
336 if (user_mode(regs)) {
337 current->thread.error_code = err;
338 current->thread.trap_no = trap;
339
340 force_sig_info(info->si_signo, info, current);
341 } else {
342 die(str, regs, err);
343 }
344}
345
346#ifdef CONFIG_GENERIC_BUG
347
348int is_valid_bugaddr(unsigned long pc)
349{
350#ifdef CONFIG_THUMB2_KERNEL
351 u16 bkpt;
352 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
353#else
354 u32 bkpt;
355 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
356#endif
357
358 if (probe_kernel_address((unsigned *)pc, bkpt))
359 return 0;
360
361 return bkpt == insn;
362}
363
364#endif
365
366static LIST_HEAD(undef_hook);
367static DEFINE_RAW_SPINLOCK(undef_lock);
368
369void register_undef_hook(struct undef_hook *hook)
370{
371 unsigned long flags;
372
373 raw_spin_lock_irqsave(&undef_lock, flags);
374 list_add(&hook->node, &undef_hook);
375 raw_spin_unlock_irqrestore(&undef_lock, flags);
376}
377
378void unregister_undef_hook(struct undef_hook *hook)
379{
380 unsigned long flags;
381
382 raw_spin_lock_irqsave(&undef_lock, flags);
383 list_del(&hook->node);
384 raw_spin_unlock_irqrestore(&undef_lock, flags);
385}
386
387static int call_undef_hook(struct pt_regs *regs, unsigned int instr)
388{
389 struct undef_hook *hook;
390 unsigned long flags;
391 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
392
393 raw_spin_lock_irqsave(&undef_lock, flags);
394 list_for_each_entry(hook, &undef_hook, node)
395 if ((instr & hook->instr_mask) == hook->instr_val &&
396 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
397 fn = hook->fn;
398 raw_spin_unlock_irqrestore(&undef_lock, flags);
399
400 return fn ? fn(regs, instr) : 1;
401}
402
403asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
404{
405 unsigned int instr;
406 siginfo_t info;
407 void __user *pc;
408
409 pc = (void __user *)instruction_pointer(regs);
410
411 if (processor_mode(regs) == SVC_MODE) {
412#ifdef CONFIG_THUMB2_KERNEL
413 if (thumb_mode(regs)) {
414 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
415 if (is_wide_instruction(instr)) {
416 u16 inst2;
417 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
418 instr = __opcode_thumb32_compose(instr, inst2);
419 }
420 } else
421#endif
422 instr = __mem_to_opcode_arm(*(u32 *) pc);
423 } else if (thumb_mode(regs)) {
424 if (get_user(instr, (u16 __user *)pc))
425 goto die_sig;
426 instr = __mem_to_opcode_thumb16(instr);
427 if (is_wide_instruction(instr)) {
428 unsigned int instr2;
429 if (get_user(instr2, (u16 __user *)pc+1))
430 goto die_sig;
431 instr2 = __mem_to_opcode_thumb16(instr2);
432 instr = __opcode_thumb32_compose(instr, instr2);
433 }
434 } else {
435 if (get_user(instr, (u32 __user *)pc))
436 goto die_sig;
437 instr = __mem_to_opcode_arm(instr);
438 }
439
440 if (call_undef_hook(regs, instr) == 0)
441 return;
442
443die_sig:
444#ifdef CONFIG_DEBUG_USER
445 if (user_debug & UDBG_UNDEFINED) {
446 printk(KERN_INFO "%s (%d): undefined instruction: pc=%p\n",
447 current->comm, task_pid_nr(current), pc);
448 __show_regs(regs);
449 dump_instr(KERN_INFO, regs);
450 }
451#endif
452
453 info.si_signo = SIGILL;
454 info.si_errno = 0;
455 info.si_code = ILL_ILLOPC;
456 info.si_addr = pc;
457
458 arm_notify_die("Oops - undefined instruction", regs, &info, 0, 6);
459}
460
461asmlinkage void do_unexp_fiq (struct pt_regs *regs)
462{
463 printk("Hmm. Unexpected FIQ received, but trying to continue\n");
464 printk("You may have a hardware problem...\n");
465}
466
467/*
468 * bad_mode handles the impossible case in the vectors. If you see one of
469 * these, then it's extremely serious, and could mean you have buggy hardware.
470 * It never returns, and never tries to sync. We hope that we can at least
471 * dump out some state information...
472 */
473asmlinkage void bad_mode(struct pt_regs *regs, int reason)
474{
475 console_verbose();
476
477 printk(KERN_CRIT "Bad mode in %s handler detected\n", handler[reason]);
478
479 die("Oops - bad mode", regs, 0);
480 local_irq_disable();
481 panic("bad mode");
482}
483
484static int bad_syscall(int n, struct pt_regs *regs)
485{
486 struct thread_info *thread = current_thread_info();
487 siginfo_t info;
488
489 if ((current->personality & PER_MASK) != PER_LINUX &&
490 thread->exec_domain->handler) {
491 thread->exec_domain->handler(n, regs);
492 return regs->ARM_r0;
493 }
494
495#ifdef CONFIG_DEBUG_USER
496 if (user_debug & UDBG_SYSCALL) {
497 printk(KERN_ERR "[%d] %s: obsolete system call %08x.\n",
498 task_pid_nr(current), current->comm, n);
499 dump_instr(KERN_ERR, regs);
500 }
501#endif
502
503 info.si_signo = SIGILL;
504 info.si_errno = 0;
505 info.si_code = ILL_ILLTRP;
506 info.si_addr = (void __user *)instruction_pointer(regs) -
507 (thumb_mode(regs) ? 2 : 4);
508
509 arm_notify_die("Oops - bad syscall", regs, &info, n, 0);
510
511 return regs->ARM_r0;
512}
513
514static long do_cache_op_restart(struct restart_block *);
515
516static inline int
517__do_cache_op(unsigned long start, unsigned long end)
518{
519 int ret;
520
521 do {
522 unsigned long chunk = min(PAGE_SIZE, end - start);
523
524 if (signal_pending(current)) {
525 struct thread_info *ti = current_thread_info();
526
527 ti->restart_block = (struct restart_block) {
528 .fn = do_cache_op_restart,
529 };
530
531 ti->arm_restart_block = (struct arm_restart_block) {
532 {
533 .cache = {
534 .start = start,
535 .end = end,
536 },
537 },
538 };
539
540 return -ERESTART_RESTARTBLOCK;
541 }
542
543 ret = flush_cache_user_range(start, start + chunk);
544 if (ret)
545 return ret;
546
547 cond_resched();
548 start += chunk;
549 } while (start < end);
550
551 return 0;
552}
553
554static long do_cache_op_restart(struct restart_block *unused)
555{
556 struct arm_restart_block *restart_block;
557
558 restart_block = ¤t_thread_info()->arm_restart_block;
559 return __do_cache_op(restart_block->cache.start,
560 restart_block->cache.end);
561}
562
563static inline int
564do_cache_op(unsigned long start, unsigned long end, int flags)
565{
566 if (end < start || flags)
567 return -EINVAL;
568
569 if (!access_ok(VERIFY_READ, start, end - start))
570 return -EFAULT;
571
572 return __do_cache_op(start, end);
573}
574
575/*
576 * Handle all unrecognised system calls.
577 * 0x9f0000 - 0x9fffff are some more esoteric system calls
578 */
579#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
580asmlinkage int arm_syscall(int no, struct pt_regs *regs)
581{
582 struct thread_info *thread = current_thread_info();
583 siginfo_t info;
584
585 if ((no >> 16) != (__ARM_NR_BASE>> 16))
586 return bad_syscall(no, regs);
587
588 switch (no & 0xffff) {
589 case 0: /* branch through 0 */
590 info.si_signo = SIGSEGV;
591 info.si_errno = 0;
592 info.si_code = SEGV_MAPERR;
593 info.si_addr = NULL;
594
595 arm_notify_die("branch through zero", regs, &info, 0, 0);
596 return 0;
597
598 case NR(breakpoint): /* SWI BREAK_POINT */
599 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
600 ptrace_break(current, regs);
601 return regs->ARM_r0;
602
603 /*
604 * Flush a region from virtual address 'r0' to virtual address 'r1'
605 * _exclusive_. There is no alignment requirement on either address;
606 * user space does not need to know the hardware cache layout.
607 *
608 * r2 contains flags. It should ALWAYS be passed as ZERO until it
609 * is defined to be something else. For now we ignore it, but may
610 * the fires of hell burn in your belly if you break this rule. ;)
611 *
612 * (at a later date, we may want to allow this call to not flush
613 * various aspects of the cache. Passing '0' will guarantee that
614 * everything necessary gets flushed to maintain consistency in
615 * the specified region).
616 */
617 case NR(cacheflush):
618 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
619
620 case NR(usr26):
621 if (!(elf_hwcap & HWCAP_26BIT))
622 break;
623 regs->ARM_cpsr &= ~MODE32_BIT;
624 return regs->ARM_r0;
625
626 case NR(usr32):
627 if (!(elf_hwcap & HWCAP_26BIT))
628 break;
629 regs->ARM_cpsr |= MODE32_BIT;
630 return regs->ARM_r0;
631
632 case NR(set_tls):
633 thread->tp_value[0] = regs->ARM_r0;
634 if (tls_emu)
635 return 0;
636 if (has_tls_reg) {
637 asm ("mcr p15, 0, %0, c13, c0, 3"
638 : : "r" (regs->ARM_r0));
639 } else {
640 /*
641 * User space must never try to access this directly.
642 * Expect your app to break eventually if you do so.
643 * The user helper at 0xffff0fe0 must be used instead.
644 * (see entry-armv.S for details)
645 */
646 *((unsigned int *)0xffff0ff0) = regs->ARM_r0;
647 }
648 return 0;
649
650#ifdef CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG
651 /*
652 * Atomically store r1 in *r2 if *r2 is equal to r0 for user space.
653 * Return zero in r0 if *MEM was changed or non-zero if no exchange
654 * happened. Also set the user C flag accordingly.
655 * If access permissions have to be fixed up then non-zero is
656 * returned and the operation has to be re-attempted.
657 *
658 * *NOTE*: This is a ghost syscall private to the kernel. Only the
659 * __kuser_cmpxchg code in entry-armv.S should be aware of its
660 * existence. Don't ever use this from user code.
661 */
662 case NR(cmpxchg):
663 for (;;) {
664 extern void do_DataAbort(unsigned long addr, unsigned int fsr,
665 struct pt_regs *regs);
666 unsigned long val;
667 unsigned long addr = regs->ARM_r2;
668 struct mm_struct *mm = current->mm;
669 pgd_t *pgd; pmd_t *pmd; pte_t *pte;
670 spinlock_t *ptl;
671
672 regs->ARM_cpsr &= ~PSR_C_BIT;
673 down_read(&mm->mmap_sem);
674 pgd = pgd_offset(mm, addr);
675 if (!pgd_present(*pgd))
676 goto bad_access;
677 pmd = pmd_offset(pgd, addr);
678 if (!pmd_present(*pmd))
679 goto bad_access;
680 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
681 if (!pte_present(*pte) || !pte_write(*pte) || !pte_dirty(*pte)) {
682 pte_unmap_unlock(pte, ptl);
683 goto bad_access;
684 }
685 val = *(unsigned long *)addr;
686 val -= regs->ARM_r0;
687 if (val == 0) {
688 *(unsigned long *)addr = regs->ARM_r1;
689 regs->ARM_cpsr |= PSR_C_BIT;
690 }
691 pte_unmap_unlock(pte, ptl);
692 up_read(&mm->mmap_sem);
693 return val;
694
695 bad_access:
696 up_read(&mm->mmap_sem);
697 /* simulate a write access fault */
698 do_DataAbort(addr, 15 + (1 << 11), regs);
699 }
700#endif
701
702 default:
703 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
704 if not implemented, rather than raising SIGILL. This
705 way the calling program can gracefully determine whether
706 a feature is supported. */
707 if ((no & 0xffff) <= 0x7ff)
708 return -ENOSYS;
709 break;
710 }
711#ifdef CONFIG_DEBUG_USER
712 /*
713 * experience shows that these seem to indicate that
714 * something catastrophic has happened
715 */
716 if (user_debug & UDBG_SYSCALL) {
717 printk("[%d] %s: arm syscall %d\n",
718 task_pid_nr(current), current->comm, no);
719 dump_instr("", regs);
720 if (user_mode(regs)) {
721 __show_regs(regs);
722 c_backtrace(regs->ARM_fp, processor_mode(regs));
723 }
724 }
725#endif
726 info.si_signo = SIGILL;
727 info.si_errno = 0;
728 info.si_code = ILL_ILLTRP;
729 info.si_addr = (void __user *)instruction_pointer(regs) -
730 (thumb_mode(regs) ? 2 : 4);
731
732 arm_notify_die("Oops - bad syscall(2)", regs, &info, no, 0);
733 return 0;
734}
735
736#ifdef CONFIG_TLS_REG_EMUL
737
738/*
739 * We might be running on an ARMv6+ processor which should have the TLS
740 * register but for some reason we can't use it, or maybe an SMP system
741 * using a pre-ARMv6 processor (there are apparently a few prototypes like
742 * that in existence) and therefore access to that register must be
743 * emulated.
744 */
745
746static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
747{
748 int reg = (instr >> 12) & 15;
749 if (reg == 15)
750 return 1;
751 regs->uregs[reg] = current_thread_info()->tp_value[0];
752 regs->ARM_pc += 4;
753 return 0;
754}
755
756static struct undef_hook arm_mrc_hook = {
757 .instr_mask = 0x0fff0fff,
758 .instr_val = 0x0e1d0f70,
759 .cpsr_mask = PSR_T_BIT,
760 .cpsr_val = 0,
761 .fn = get_tp_trap,
762};
763
764static int __init arm_mrc_hook_init(void)
765{
766 register_undef_hook(&arm_mrc_hook);
767 return 0;
768}
769
770late_initcall(arm_mrc_hook_init);
771
772#endif
773
774void __bad_xchg(volatile void *ptr, int size)
775{
776 printk("xchg: bad data size: pc 0x%p, ptr 0x%p, size %d\n",
777 __builtin_return_address(0), ptr, size);
778 BUG();
779}
780EXPORT_SYMBOL(__bad_xchg);
781
782/*
783 * A data abort trap was taken, but we did not handle the instruction.
784 * Try to abort the user program, or panic if it was the kernel.
785 */
786asmlinkage void
787baddataabort(int code, unsigned long instr, struct pt_regs *regs)
788{
789 unsigned long addr = instruction_pointer(regs);
790 siginfo_t info;
791
792#ifdef CONFIG_DEBUG_USER
793 if (user_debug & UDBG_BADABORT) {
794 printk(KERN_ERR "[%d] %s: bad data abort: code %d instr 0x%08lx\n",
795 task_pid_nr(current), current->comm, code, instr);
796 dump_instr(KERN_ERR, regs);
797 show_pte(current->mm, addr);
798 }
799#endif
800
801 info.si_signo = SIGILL;
802 info.si_errno = 0;
803 info.si_code = ILL_ILLOPC;
804 info.si_addr = (void __user *)addr;
805
806 arm_notify_die("unknown data abort code", regs, &info, instr, 0);
807}
808
809void __readwrite_bug(const char *fn)
810{
811 printk("%s called, but not implemented\n", fn);
812 BUG();
813}
814EXPORT_SYMBOL(__readwrite_bug);
815
816void __pte_error(const char *file, int line, pte_t pte)
817{
818 printk("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
819}
820
821void __pmd_error(const char *file, int line, pmd_t pmd)
822{
823 printk("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
824}
825
826void __pgd_error(const char *file, int line, pgd_t pgd)
827{
828 printk("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
829}
830
831asmlinkage void __div0(void)
832{
833 printk("Division by zero in kernel.\n");
834 dump_stack();
835}
836EXPORT_SYMBOL(__div0);
837
838void abort(void)
839{
840 BUG();
841
842 /* if that doesn't kill us, halt */
843 panic("Oops failed to kill thread");
844}
845EXPORT_SYMBOL(abort);
846
847void __init trap_init(void)
848{
849 return;
850}
851
852#ifdef CONFIG_KUSER_HELPERS
853static void __init kuser_init(void *vectors)
854{
855 extern char __kuser_helper_start[], __kuser_helper_end[];
856 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
857
858 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
859
860 /*
861 * vectors + 0xfe0 = __kuser_get_tls
862 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
863 */
864 if (tls_emu || has_tls_reg)
865 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
866}
867#else
868static inline void __init kuser_init(void *vectors)
869{
870}
871#endif
872
873void __init early_trap_init(void *vectors_base)
874{
875#ifndef CONFIG_CPU_V7M
876 unsigned long vectors = (unsigned long)vectors_base;
877 extern char __stubs_start[], __stubs_end[];
878 extern char __vectors_start[], __vectors_end[];
879 unsigned i;
880
881 vectors_page = vectors_base;
882
883 /*
884 * Poison the vectors page with an undefined instruction. This
885 * instruction is chosen to be undefined for both ARM and Thumb
886 * ISAs. The Thumb version is an undefined instruction with a
887 * branch back to the undefined instruction.
888 */
889 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
890 ((u32 *)vectors_base)[i] = 0xe7fddef1;
891
892 /*
893 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
894 * into the vector page, mapped at 0xffff0000, and ensure these
895 * are visible to the instruction stream.
896 */
897 memcpy((void *)vectors, __vectors_start, __vectors_end - __vectors_start);
898 memcpy((void *)vectors + 0x1000, __stubs_start, __stubs_end - __stubs_start);
899
900 kuser_init(vectors_base);
901
902 flush_icache_range(vectors, vectors + PAGE_SIZE * 2);
903 modify_domain(DOMAIN_USER, DOMAIN_CLIENT);
904#else /* ifndef CONFIG_CPU_V7M */
905 /*
906 * on V7-M there is no need to copy the vector table to a dedicated
907 * memory area. The address is configurable and so a table in the kernel
908 * image can be used.
909 */
910#endif
911}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/arch/arm/kernel/traps.c
4 *
5 * Copyright (C) 1995-2009 Russell King
6 * Fragments that appear the same as linux/arch/i386/kernel/traps.c (C) Linus Torvalds
7 *
8 * 'traps.c' handles hardware exceptions after we have saved some state in
9 * 'linux/arch/arm/lib/traps.S'. Mostly a debugging aid, but will probably
10 * kill the offending process.
11 */
12#include <linux/signal.h>
13#include <linux/personality.h>
14#include <linux/kallsyms.h>
15#include <linux/spinlock.h>
16#include <linux/uaccess.h>
17#include <linux/hardirq.h>
18#include <linux/kdebug.h>
19#include <linux/kprobes.h>
20#include <linux/module.h>
21#include <linux/kexec.h>
22#include <linux/bug.h>
23#include <linux/delay.h>
24#include <linux/init.h>
25#include <linux/sched/signal.h>
26#include <linux/sched/debug.h>
27#include <linux/sched/task_stack.h>
28#include <linux/irq.h>
29#include <linux/vmalloc.h>
30
31#include <linux/atomic.h>
32#include <asm/cacheflush.h>
33#include <asm/exception.h>
34#include <asm/spectre.h>
35#include <asm/unistd.h>
36#include <asm/traps.h>
37#include <asm/ptrace.h>
38#include <asm/unwind.h>
39#include <asm/tls.h>
40#include <asm/stacktrace.h>
41#include <asm/system_misc.h>
42#include <asm/opcodes.h>
43
44
45static const char *handler[]= {
46 "prefetch abort",
47 "data abort",
48 "address exception",
49 "interrupt",
50 "undefined instruction",
51};
52
53void *vectors_page;
54
55#ifdef CONFIG_DEBUG_USER
56unsigned int user_debug;
57
58static int __init user_debug_setup(char *str)
59{
60 get_option(&str, &user_debug);
61 return 1;
62}
63__setup("user_debug=", user_debug_setup);
64#endif
65
66void dump_backtrace_entry(unsigned long where, unsigned long from,
67 unsigned long frame, const char *loglvl)
68{
69 unsigned long end = frame + 4 + sizeof(struct pt_regs);
70
71 if (IS_ENABLED(CONFIG_UNWINDER_FRAME_POINTER) &&
72 IS_ENABLED(CONFIG_CC_IS_GCC) &&
73 end > ALIGN(frame, THREAD_SIZE)) {
74 /*
75 * If we are walking past the end of the stack, it may be due
76 * to the fact that we are on an IRQ or overflow stack. In this
77 * case, we can load the address of the other stack from the
78 * frame record.
79 */
80 frame = ((unsigned long *)frame)[-2] - 4;
81 end = frame + 4 + sizeof(struct pt_regs);
82 }
83
84#ifndef CONFIG_KALLSYMS
85 printk("%sFunction entered at [<%08lx>] from [<%08lx>]\n",
86 loglvl, where, from);
87#elif defined CONFIG_BACKTRACE_VERBOSE
88 printk("%s[<%08lx>] (%ps) from [<%08lx>] (%pS)\n",
89 loglvl, where, (void *)where, from, (void *)from);
90#else
91 printk("%s %ps from %pS\n", loglvl, (void *)where, (void *)from);
92#endif
93
94 if (in_entry_text(from) && end <= ALIGN(frame, THREAD_SIZE))
95 dump_mem(loglvl, "Exception stack", frame + 4, end);
96}
97
98void dump_backtrace_stm(u32 *stack, u32 instruction, const char *loglvl)
99{
100 char str[80], *p;
101 unsigned int x;
102 int reg;
103
104 for (reg = 10, x = 0, p = str; reg >= 0; reg--) {
105 if (instruction & BIT(reg)) {
106 p += sprintf(p, " r%d:%08x", reg, *stack--);
107 if (++x == 6) {
108 x = 0;
109 p = str;
110 printk("%s%s\n", loglvl, str);
111 }
112 }
113 }
114 if (p != str)
115 printk("%s%s\n", loglvl, str);
116}
117
118#ifndef CONFIG_ARM_UNWIND
119/*
120 * Stack pointers should always be within the kernels view of
121 * physical memory. If it is not there, then we can't dump
122 * out any information relating to the stack.
123 */
124static int verify_stack(unsigned long sp)
125{
126 if (sp < PAGE_OFFSET ||
127 (!IS_ENABLED(CONFIG_VMAP_STACK) &&
128 sp > (unsigned long)high_memory && high_memory != NULL))
129 return -EFAULT;
130
131 return 0;
132}
133#endif
134
135/*
136 * Dump out the contents of some memory nicely...
137 */
138void dump_mem(const char *lvl, const char *str, unsigned long bottom,
139 unsigned long top)
140{
141 unsigned long first;
142 int i;
143
144 printk("%s%s(0x%08lx to 0x%08lx)\n", lvl, str, bottom, top);
145
146 for (first = bottom & ~31; first < top; first += 32) {
147 unsigned long p;
148 char str[sizeof(" 12345678") * 8 + 1];
149
150 memset(str, ' ', sizeof(str));
151 str[sizeof(str) - 1] = '\0';
152
153 for (p = first, i = 0; i < 8 && p < top; i++, p += 4) {
154 if (p >= bottom && p < top) {
155 unsigned long val;
156 if (!get_kernel_nofault(val, (unsigned long *)p))
157 sprintf(str + i * 9, " %08lx", val);
158 else
159 sprintf(str + i * 9, " ????????");
160 }
161 }
162 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
163 }
164}
165
166static void dump_instr(const char *lvl, struct pt_regs *regs)
167{
168 unsigned long addr = instruction_pointer(regs);
169 const int thumb = thumb_mode(regs);
170 const int width = thumb ? 4 : 8;
171 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
172 int i;
173
174 /*
175 * Note that we now dump the code first, just in case the backtrace
176 * kills us.
177 */
178
179 for (i = -4; i < 1 + !!thumb; i++) {
180 unsigned int val, bad;
181
182 if (thumb) {
183 u16 tmp;
184
185 if (user_mode(regs))
186 bad = get_user(tmp, &((u16 __user *)addr)[i]);
187 else
188 bad = get_kernel_nofault(tmp, &((u16 *)addr)[i]);
189
190 val = __mem_to_opcode_thumb16(tmp);
191 } else {
192 if (user_mode(regs))
193 bad = get_user(val, &((u32 __user *)addr)[i]);
194 else
195 bad = get_kernel_nofault(val, &((u32 *)addr)[i]);
196
197 val = __mem_to_opcode_arm(val);
198 }
199
200 if (!bad)
201 p += sprintf(p, i == 0 ? "(%0*x) " : "%0*x ",
202 width, val);
203 else {
204 p += sprintf(p, "bad PC value");
205 break;
206 }
207 }
208 printk("%sCode: %s\n", lvl, str);
209}
210
211#ifdef CONFIG_ARM_UNWIND
212void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
213 const char *loglvl)
214{
215 unwind_backtrace(regs, tsk, loglvl);
216}
217#else
218void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk,
219 const char *loglvl)
220{
221 unsigned int fp, mode;
222 int ok = 1;
223
224 printk("%sCall trace: ", loglvl);
225
226 if (!tsk)
227 tsk = current;
228
229 if (regs) {
230 fp = frame_pointer(regs);
231 mode = processor_mode(regs);
232 } else if (tsk != current) {
233 fp = thread_saved_fp(tsk);
234 mode = 0x10;
235 } else {
236 asm("mov %0, fp" : "=r" (fp) : : "cc");
237 mode = 0x10;
238 }
239
240 if (!fp) {
241 pr_cont("no frame pointer");
242 ok = 0;
243 } else if (verify_stack(fp)) {
244 pr_cont("invalid frame pointer 0x%08x", fp);
245 ok = 0;
246 } else if (fp < (unsigned long)end_of_stack(tsk))
247 pr_cont("frame pointer underflow");
248 pr_cont("\n");
249
250 if (ok)
251 c_backtrace(fp, mode, loglvl);
252}
253#endif
254
255void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
256{
257 dump_backtrace(NULL, tsk, loglvl);
258 barrier();
259}
260
261#ifdef CONFIG_PREEMPT
262#define S_PREEMPT " PREEMPT"
263#elif defined(CONFIG_PREEMPT_RT)
264#define S_PREEMPT " PREEMPT_RT"
265#else
266#define S_PREEMPT ""
267#endif
268#ifdef CONFIG_SMP
269#define S_SMP " SMP"
270#else
271#define S_SMP ""
272#endif
273#ifdef CONFIG_THUMB2_KERNEL
274#define S_ISA " THUMB2"
275#else
276#define S_ISA " ARM"
277#endif
278
279static int __die(const char *str, int err, struct pt_regs *regs)
280{
281 struct task_struct *tsk = current;
282 static int die_counter;
283 int ret;
284
285 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP S_ISA "\n",
286 str, err, ++die_counter);
287
288 /* trap and error numbers are mostly meaningless on ARM */
289 ret = notify_die(DIE_OOPS, str, regs, err, tsk->thread.trap_no, SIGSEGV);
290 if (ret == NOTIFY_STOP)
291 return 1;
292
293 print_modules();
294 __show_regs(regs);
295 __show_regs_alloc_free(regs);
296 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
297 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), end_of_stack(tsk));
298
299 if (!user_mode(regs) || in_interrupt()) {
300 dump_mem(KERN_EMERG, "Stack: ", regs->ARM_sp,
301 ALIGN(regs->ARM_sp - THREAD_SIZE, THREAD_ALIGN)
302 + THREAD_SIZE);
303 dump_backtrace(regs, tsk, KERN_EMERG);
304 dump_instr(KERN_EMERG, regs);
305 }
306
307 return 0;
308}
309
310static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
311static int die_owner = -1;
312static unsigned int die_nest_count;
313
314static unsigned long oops_begin(void)
315{
316 int cpu;
317 unsigned long flags;
318
319 oops_enter();
320
321 /* racy, but better than risking deadlock. */
322 raw_local_irq_save(flags);
323 cpu = smp_processor_id();
324 if (!arch_spin_trylock(&die_lock)) {
325 if (cpu == die_owner)
326 /* nested oops. should stop eventually */;
327 else
328 arch_spin_lock(&die_lock);
329 }
330 die_nest_count++;
331 die_owner = cpu;
332 console_verbose();
333 bust_spinlocks(1);
334 return flags;
335}
336
337static void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
338{
339 if (regs && kexec_should_crash(current))
340 crash_kexec(regs);
341
342 bust_spinlocks(0);
343 die_owner = -1;
344 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
345 die_nest_count--;
346 if (!die_nest_count)
347 /* Nest count reaches zero, release the lock. */
348 arch_spin_unlock(&die_lock);
349 raw_local_irq_restore(flags);
350 oops_exit();
351
352 if (in_interrupt())
353 panic("Fatal exception in interrupt");
354 if (panic_on_oops)
355 panic("Fatal exception");
356 if (signr)
357 make_task_dead(signr);
358}
359
360/*
361 * This function is protected against re-entrancy.
362 */
363void die(const char *str, struct pt_regs *regs, int err)
364{
365 enum bug_trap_type bug_type = BUG_TRAP_TYPE_NONE;
366 unsigned long flags = oops_begin();
367 int sig = SIGSEGV;
368
369 if (!user_mode(regs))
370 bug_type = report_bug(regs->ARM_pc, regs);
371 if (bug_type != BUG_TRAP_TYPE_NONE)
372 str = "Oops - BUG";
373
374 if (__die(str, err, regs))
375 sig = 0;
376
377 oops_end(flags, regs, sig);
378}
379
380void arm_notify_die(const char *str, struct pt_regs *regs,
381 int signo, int si_code, void __user *addr,
382 unsigned long err, unsigned long trap)
383{
384 if (user_mode(regs)) {
385 current->thread.error_code = err;
386 current->thread.trap_no = trap;
387
388 force_sig_fault(signo, si_code, addr);
389 } else {
390 die(str, regs, err);
391 }
392}
393
394#ifdef CONFIG_GENERIC_BUG
395
396int is_valid_bugaddr(unsigned long pc)
397{
398#ifdef CONFIG_THUMB2_KERNEL
399 u16 bkpt;
400 u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);
401#else
402 u32 bkpt;
403 u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);
404#endif
405
406 if (get_kernel_nofault(bkpt, (void *)pc))
407 return 0;
408
409 return bkpt == insn;
410}
411
412#endif
413
414static LIST_HEAD(undef_hook);
415static DEFINE_RAW_SPINLOCK(undef_lock);
416
417void register_undef_hook(struct undef_hook *hook)
418{
419 unsigned long flags;
420
421 raw_spin_lock_irqsave(&undef_lock, flags);
422 list_add(&hook->node, &undef_hook);
423 raw_spin_unlock_irqrestore(&undef_lock, flags);
424}
425
426void unregister_undef_hook(struct undef_hook *hook)
427{
428 unsigned long flags;
429
430 raw_spin_lock_irqsave(&undef_lock, flags);
431 list_del(&hook->node);
432 raw_spin_unlock_irqrestore(&undef_lock, flags);
433}
434
435static nokprobe_inline
436int call_undef_hook(struct pt_regs *regs, unsigned int instr)
437{
438 struct undef_hook *hook;
439 unsigned long flags;
440 int (*fn)(struct pt_regs *regs, unsigned int instr) = NULL;
441
442 raw_spin_lock_irqsave(&undef_lock, flags);
443 list_for_each_entry(hook, &undef_hook, node)
444 if ((instr & hook->instr_mask) == hook->instr_val &&
445 (regs->ARM_cpsr & hook->cpsr_mask) == hook->cpsr_val)
446 fn = hook->fn;
447 raw_spin_unlock_irqrestore(&undef_lock, flags);
448
449 return fn ? fn(regs, instr) : 1;
450}
451
452asmlinkage void do_undefinstr(struct pt_regs *regs)
453{
454 unsigned int instr;
455 void __user *pc;
456
457 pc = (void __user *)instruction_pointer(regs);
458
459 if (processor_mode(regs) == SVC_MODE) {
460#ifdef CONFIG_THUMB2_KERNEL
461 if (thumb_mode(regs)) {
462 instr = __mem_to_opcode_thumb16(((u16 *)pc)[0]);
463 if (is_wide_instruction(instr)) {
464 u16 inst2;
465 inst2 = __mem_to_opcode_thumb16(((u16 *)pc)[1]);
466 instr = __opcode_thumb32_compose(instr, inst2);
467 }
468 } else
469#endif
470 instr = __mem_to_opcode_arm(*(u32 *) pc);
471 } else if (thumb_mode(regs)) {
472 if (get_user(instr, (u16 __user *)pc))
473 goto die_sig;
474 instr = __mem_to_opcode_thumb16(instr);
475 if (is_wide_instruction(instr)) {
476 unsigned int instr2;
477 if (get_user(instr2, (u16 __user *)pc+1))
478 goto die_sig;
479 instr2 = __mem_to_opcode_thumb16(instr2);
480 instr = __opcode_thumb32_compose(instr, instr2);
481 }
482 } else {
483 if (get_user(instr, (u32 __user *)pc))
484 goto die_sig;
485 instr = __mem_to_opcode_arm(instr);
486 }
487
488 if (call_undef_hook(regs, instr) == 0)
489 return;
490
491die_sig:
492#ifdef CONFIG_DEBUG_USER
493 if (user_debug & UDBG_UNDEFINED) {
494 pr_info("%s (%d): undefined instruction: pc=%px\n",
495 current->comm, task_pid_nr(current), pc);
496 __show_regs(regs);
497 dump_instr(KERN_INFO, regs);
498 }
499#endif
500 arm_notify_die("Oops - undefined instruction", regs,
501 SIGILL, ILL_ILLOPC, pc, 0, 6);
502}
503NOKPROBE_SYMBOL(do_undefinstr)
504
505/*
506 * Handle FIQ similarly to NMI on x86 systems.
507 *
508 * The runtime environment for NMIs is extremely restrictive
509 * (NMIs can pre-empt critical sections meaning almost all locking is
510 * forbidden) meaning this default FIQ handling must only be used in
511 * circumstances where non-maskability improves robustness, such as
512 * watchdog or debug logic.
513 *
514 * This handler is not appropriate for general purpose use in drivers
515 * platform code and can be overrideen using set_fiq_handler.
516 */
517asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs)
518{
519 struct pt_regs *old_regs = set_irq_regs(regs);
520
521 nmi_enter();
522
523 /* nop. FIQ handlers for special arch/arm features can be added here. */
524
525 nmi_exit();
526
527 set_irq_regs(old_regs);
528}
529
530/*
531 * bad_mode handles the impossible case in the vectors. If you see one of
532 * these, then it's extremely serious, and could mean you have buggy hardware.
533 * It never returns, and never tries to sync. We hope that we can at least
534 * dump out some state information...
535 */
536asmlinkage void bad_mode(struct pt_regs *regs, int reason)
537{
538 console_verbose();
539
540 pr_crit("Bad mode in %s handler detected\n", handler[reason]);
541
542 die("Oops - bad mode", regs, 0);
543 local_irq_disable();
544 panic("bad mode");
545}
546
547static int bad_syscall(int n, struct pt_regs *regs)
548{
549 if ((current->personality & PER_MASK) != PER_LINUX) {
550 send_sig(SIGSEGV, current, 1);
551 return regs->ARM_r0;
552 }
553
554#ifdef CONFIG_DEBUG_USER
555 if (user_debug & UDBG_SYSCALL) {
556 pr_err("[%d] %s: obsolete system call %08x.\n",
557 task_pid_nr(current), current->comm, n);
558 dump_instr(KERN_ERR, regs);
559 }
560#endif
561
562 arm_notify_die("Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
563 (void __user *)instruction_pointer(regs) -
564 (thumb_mode(regs) ? 2 : 4),
565 n, 0);
566
567 return regs->ARM_r0;
568}
569
570static inline int
571__do_cache_op(unsigned long start, unsigned long end)
572{
573 unsigned int ua_flags;
574 int ret;
575
576 do {
577 unsigned long chunk = min(PAGE_SIZE, end - start);
578
579 if (fatal_signal_pending(current))
580 return 0;
581
582 ua_flags = uaccess_save_and_enable();
583 ret = flush_icache_user_range(start, start + chunk);
584 uaccess_restore(ua_flags);
585 if (ret)
586 return ret;
587
588 cond_resched();
589 start += chunk;
590 } while (start < end);
591
592 return 0;
593}
594
595static inline int
596do_cache_op(unsigned long start, unsigned long end, int flags)
597{
598 if (end < start || flags)
599 return -EINVAL;
600
601 if (!access_ok((void __user *)start, end - start))
602 return -EFAULT;
603
604 return __do_cache_op(start, end);
605}
606
607/*
608 * Handle all unrecognised system calls.
609 * 0x9f0000 - 0x9fffff are some more esoteric system calls
610 */
611#define NR(x) ((__ARM_NR_##x) - __ARM_NR_BASE)
612asmlinkage int arm_syscall(int no, struct pt_regs *regs)
613{
614 if ((no >> 16) != (__ARM_NR_BASE>> 16))
615 return bad_syscall(no, regs);
616
617 switch (no & 0xffff) {
618 case 0: /* branch through 0 */
619 arm_notify_die("branch through zero", regs,
620 SIGSEGV, SEGV_MAPERR, NULL, 0, 0);
621 return 0;
622
623 case NR(breakpoint): /* SWI BREAK_POINT */
624 regs->ARM_pc -= thumb_mode(regs) ? 2 : 4;
625 ptrace_break(regs);
626 return regs->ARM_r0;
627
628 /*
629 * Flush a region from virtual address 'r0' to virtual address 'r1'
630 * _exclusive_. There is no alignment requirement on either address;
631 * user space does not need to know the hardware cache layout.
632 *
633 * r2 contains flags. It should ALWAYS be passed as ZERO until it
634 * is defined to be something else. For now we ignore it, but may
635 * the fires of hell burn in your belly if you break this rule. ;)
636 *
637 * (at a later date, we may want to allow this call to not flush
638 * various aspects of the cache. Passing '0' will guarantee that
639 * everything necessary gets flushed to maintain consistency in
640 * the specified region).
641 */
642 case NR(cacheflush):
643 return do_cache_op(regs->ARM_r0, regs->ARM_r1, regs->ARM_r2);
644
645 case NR(usr26):
646 if (!(elf_hwcap & HWCAP_26BIT))
647 break;
648 regs->ARM_cpsr &= ~MODE32_BIT;
649 return regs->ARM_r0;
650
651 case NR(usr32):
652 if (!(elf_hwcap & HWCAP_26BIT))
653 break;
654 regs->ARM_cpsr |= MODE32_BIT;
655 return regs->ARM_r0;
656
657 case NR(set_tls):
658 set_tls(regs->ARM_r0);
659 return 0;
660
661 case NR(get_tls):
662 return current_thread_info()->tp_value[0];
663
664 default:
665 /* Calls 9f00xx..9f07ff are defined to return -ENOSYS
666 if not implemented, rather than raising SIGILL. This
667 way the calling program can gracefully determine whether
668 a feature is supported. */
669 if ((no & 0xffff) <= 0x7ff)
670 return -ENOSYS;
671 break;
672 }
673#ifdef CONFIG_DEBUG_USER
674 /*
675 * experience shows that these seem to indicate that
676 * something catastrophic has happened
677 */
678 if (user_debug & UDBG_SYSCALL) {
679 pr_err("[%d] %s: arm syscall %d\n",
680 task_pid_nr(current), current->comm, no);
681 dump_instr(KERN_ERR, regs);
682 if (user_mode(regs)) {
683 __show_regs(regs);
684 c_backtrace(frame_pointer(regs), processor_mode(regs), KERN_ERR);
685 }
686 }
687#endif
688 arm_notify_die("Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
689 (void __user *)instruction_pointer(regs) -
690 (thumb_mode(regs) ? 2 : 4),
691 no, 0);
692 return 0;
693}
694
695#ifdef CONFIG_TLS_REG_EMUL
696
697/*
698 * We might be running on an ARMv6+ processor which should have the TLS
699 * register but for some reason we can't use it, or maybe an SMP system
700 * using a pre-ARMv6 processor (there are apparently a few prototypes like
701 * that in existence) and therefore access to that register must be
702 * emulated.
703 */
704
705static int get_tp_trap(struct pt_regs *regs, unsigned int instr)
706{
707 int reg = (instr >> 12) & 15;
708 if (reg == 15)
709 return 1;
710 regs->uregs[reg] = current_thread_info()->tp_value[0];
711 regs->ARM_pc += 4;
712 return 0;
713}
714
715static struct undef_hook arm_mrc_hook = {
716 .instr_mask = 0x0fff0fff,
717 .instr_val = 0x0e1d0f70,
718 .cpsr_mask = PSR_T_BIT,
719 .cpsr_val = 0,
720 .fn = get_tp_trap,
721};
722
723static int __init arm_mrc_hook_init(void)
724{
725 register_undef_hook(&arm_mrc_hook);
726 return 0;
727}
728
729late_initcall(arm_mrc_hook_init);
730
731#endif
732
733/*
734 * A data abort trap was taken, but we did not handle the instruction.
735 * Try to abort the user program, or panic if it was the kernel.
736 */
737asmlinkage void
738baddataabort(int code, unsigned long instr, struct pt_regs *regs)
739{
740 unsigned long addr = instruction_pointer(regs);
741
742#ifdef CONFIG_DEBUG_USER
743 if (user_debug & UDBG_BADABORT) {
744 pr_err("8<--- cut here ---\n");
745 pr_err("[%d] %s: bad data abort: code %d instr 0x%08lx\n",
746 task_pid_nr(current), current->comm, code, instr);
747 dump_instr(KERN_ERR, regs);
748 show_pte(KERN_ERR, current->mm, addr);
749 }
750#endif
751
752 arm_notify_die("unknown data abort code", regs,
753 SIGILL, ILL_ILLOPC, (void __user *)addr, instr, 0);
754}
755
756void __readwrite_bug(const char *fn)
757{
758 pr_err("%s called, but not implemented\n", fn);
759 BUG();
760}
761EXPORT_SYMBOL(__readwrite_bug);
762
763#ifdef CONFIG_MMU
764void __pte_error(const char *file, int line, pte_t pte)
765{
766 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
767}
768
769void __pmd_error(const char *file, int line, pmd_t pmd)
770{
771 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
772}
773
774void __pgd_error(const char *file, int line, pgd_t pgd)
775{
776 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
777}
778#endif
779
780asmlinkage void __div0(void)
781{
782 pr_err("Division by zero in kernel.\n");
783 dump_stack();
784}
785EXPORT_SYMBOL(__div0);
786
787void abort(void)
788{
789 BUG();
790
791 /* if that doesn't kill us, halt */
792 panic("Oops failed to kill thread");
793}
794
795#ifdef CONFIG_KUSER_HELPERS
796static void __init kuser_init(void *vectors)
797{
798 extern char __kuser_helper_start[], __kuser_helper_end[];
799 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
800
801 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
802
803 /*
804 * vectors + 0xfe0 = __kuser_get_tls
805 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
806 */
807 if (tls_emu || has_tls_reg)
808 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
809}
810#else
811static inline void __init kuser_init(void *vectors)
812{
813}
814#endif
815
816#ifndef CONFIG_CPU_V7M
817static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
818{
819 memcpy(vma, lma_start, lma_end - lma_start);
820}
821
822static void flush_vectors(void *vma, size_t offset, size_t size)
823{
824 unsigned long start = (unsigned long)vma + offset;
825 unsigned long end = start + size;
826
827 flush_icache_range(start, end);
828}
829
830#ifdef CONFIG_HARDEN_BRANCH_HISTORY
831int spectre_bhb_update_vectors(unsigned int method)
832{
833 extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
834 extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
835 void *vec_start, *vec_end;
836
837 if (system_state >= SYSTEM_FREEING_INITMEM) {
838 pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
839 smp_processor_id());
840 return SPECTRE_VULNERABLE;
841 }
842
843 switch (method) {
844 case SPECTRE_V2_METHOD_LOOP8:
845 vec_start = __vectors_bhb_loop8_start;
846 vec_end = __vectors_bhb_loop8_end;
847 break;
848
849 case SPECTRE_V2_METHOD_BPIALL:
850 vec_start = __vectors_bhb_bpiall_start;
851 vec_end = __vectors_bhb_bpiall_end;
852 break;
853
854 default:
855 pr_err("CPU%u: unknown Spectre BHB state %d\n",
856 smp_processor_id(), method);
857 return SPECTRE_VULNERABLE;
858 }
859
860 copy_from_lma(vectors_page, vec_start, vec_end);
861 flush_vectors(vectors_page, 0, vec_end - vec_start);
862
863 return SPECTRE_MITIGATED;
864}
865#endif
866
867void __init early_trap_init(void *vectors_base)
868{
869 extern char __stubs_start[], __stubs_end[];
870 extern char __vectors_start[], __vectors_end[];
871 unsigned i;
872
873 vectors_page = vectors_base;
874
875 /*
876 * Poison the vectors page with an undefined instruction. This
877 * instruction is chosen to be undefined for both ARM and Thumb
878 * ISAs. The Thumb version is an undefined instruction with a
879 * branch back to the undefined instruction.
880 */
881 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
882 ((u32 *)vectors_base)[i] = 0xe7fddef1;
883
884 /*
885 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
886 * into the vector page, mapped at 0xffff0000, and ensure these
887 * are visible to the instruction stream.
888 */
889 copy_from_lma(vectors_base, __vectors_start, __vectors_end);
890 copy_from_lma(vectors_base + 0x1000, __stubs_start, __stubs_end);
891
892 kuser_init(vectors_base);
893
894 flush_vectors(vectors_base, 0, PAGE_SIZE * 2);
895}
896#else /* ifndef CONFIG_CPU_V7M */
897void __init early_trap_init(void *vectors_base)
898{
899 /*
900 * on V7-M there is no need to copy the vector table to a dedicated
901 * memory area. The address is configurable and so a table in the kernel
902 * image can be used.
903 */
904}
905#endif
906
907#ifdef CONFIG_VMAP_STACK
908
909DECLARE_PER_CPU(u8 *, irq_stack_ptr);
910
911asmlinkage DEFINE_PER_CPU(u8 *, overflow_stack_ptr);
912
913static int __init allocate_overflow_stacks(void)
914{
915 u8 *stack;
916 int cpu;
917
918 for_each_possible_cpu(cpu) {
919 stack = (u8 *)__get_free_page(GFP_KERNEL);
920 if (WARN_ON(!stack))
921 return -ENOMEM;
922 per_cpu(overflow_stack_ptr, cpu) = &stack[OVERFLOW_STACK_SIZE];
923 }
924 return 0;
925}
926early_initcall(allocate_overflow_stacks);
927
928asmlinkage void handle_bad_stack(struct pt_regs *regs)
929{
930 unsigned long tsk_stk = (unsigned long)current->stack;
931#ifdef CONFIG_IRQSTACKS
932 unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
933#endif
934 unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
935
936 console_verbose();
937 pr_emerg("Insufficient stack space to handle exception!");
938
939 pr_emerg("Task stack: [0x%08lx..0x%08lx]\n",
940 tsk_stk, tsk_stk + THREAD_SIZE);
941#ifdef CONFIG_IRQSTACKS
942 pr_emerg("IRQ stack: [0x%08lx..0x%08lx]\n",
943 irq_stk - THREAD_SIZE, irq_stk);
944#endif
945 pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
946 ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
947
948 die("kernel stack overflow", regs, 0);
949}
950
951#ifndef CONFIG_ARM_LPAE
952/*
953 * Normally, we rely on the logic in do_translation_fault() to update stale PMD
954 * entries covering the vmalloc space in a task's page tables when it first
955 * accesses the region in question. Unfortunately, this is not sufficient when
956 * the task stack resides in the vmalloc region, as do_translation_fault() is a
957 * C function that needs a stack to run.
958 *
959 * So we need to ensure that these PMD entries are up to date *before* the MM
960 * switch. As we already have some logic in the MM switch path that takes care
961 * of this, let's trigger it by bumping the counter every time the core vmalloc
962 * code modifies a PMD entry in the vmalloc region. Use release semantics on
963 * the store so that other CPUs observing the counter's new value are
964 * guaranteed to see the updated page table entries as well.
965 */
966void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
967{
968 if (start < VMALLOC_END && end > VMALLOC_START)
969 atomic_inc_return_release(&init_mm.context.vmalloc_seq);
970}
971#endif
972#endif