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