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