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