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(buf: p, fmt: " 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(buf: str + i * 9, fmt: " %08lx", val);
157 else
158 sprintf(buf: str + i * 9, fmt: " ????????");
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(buf: p, fmt: i == 0 ? "(%0*x) " : "%0*x ",
201 width, val);
202 else {
203 p += sprintf(buf: p, fmt: "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("%sCall trace: ", 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(sp: fp)) {
243 pr_cont("invalid frame pointer 0x%08x", fp);
244 ok = 0;
245 } else if (fp < (unsigned long)end_of_stack(task: 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(val: DIE_OOPS, str, regs, err, trap: 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(yes: 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(yes: 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(fmt: "Fatal exception in interrupt");
353 if (panic_on_oops)
354 panic(fmt: "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(bug_addr: 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, signr: 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(sig: signo, code: 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(new: &hook->node, head: &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(entry: &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(str: "Oops - undefined instruction", regs,
500 SIGILL, ILL_ILLOPC, addr: pc, err: 0, trap: 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(fmt: "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(str: "Oops - bad syscall", regs, SIGILL, ILL_ILLTRP,
562 addr: (void __user *)instruction_pointer(regs) -
563 (thumb_mode(regs) ? 2 : 4),
564 err: n, trap: 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, end: 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(n: no, regs);
612
613 switch (no & 0xffff) {
614 case 0: /* branch through 0 */
615 arm_notify_die(str: "branch through zero", regs,
616 SIGSEGV, SEGV_MAPERR, NULL, err: 0, trap: 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(start: regs->ARM_r0, end: regs->ARM_r1, flags: 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(str: "Oops - bad syscall(2)", regs, SIGILL, ILL_ILLTRP,
685 addr: (void __user *)instruction_pointer(regs) -
686 (thumb_mode(regs) ? 2 : 4),
687 err: no, trap: 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(str: "unknown data abort code", regs,
749 SIGILL, ILL_ILLOPC, addr: (void __user *)addr, err: instr, trap: 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
759#ifdef CONFIG_MMU
760void __pte_error(const char *file, int line, pte_t pte)
761{
762 pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
763}
764
765void __pmd_error(const char *file, int line, pmd_t pmd)
766{
767 pr_err("%s:%d: bad pmd %08llx.\n", file, line, (long long)pmd_val(pmd));
768}
769
770void __pgd_error(const char *file, int line, pgd_t pgd)
771{
772 pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
773}
774#endif
775
776asmlinkage void __div0(void)
777{
778 pr_err("Division by zero in kernel.\n");
779 dump_stack();
780}
781EXPORT_SYMBOL(__div0);
782
783void abort(void)
784{
785 BUG();
786
787 /* if that doesn't kill us, halt */
788 panic(fmt: "Oops failed to kill thread");
789}
790
791#ifdef CONFIG_KUSER_HELPERS
792static void __init kuser_init(void *vectors)
793{
794 extern char __kuser_helper_start[], __kuser_helper_end[];
795 int kuser_sz = __kuser_helper_end - __kuser_helper_start;
796
797 memcpy(vectors + 0x1000 - kuser_sz, __kuser_helper_start, kuser_sz);
798
799 /*
800 * vectors + 0xfe0 = __kuser_get_tls
801 * vectors + 0xfe8 = hardware TLS instruction at 0xffff0fe8
802 */
803 if (tls_emu || has_tls_reg)
804 memcpy(vectors + 0xfe0, vectors + 0xfe8, 4);
805}
806#else
807static inline void __init kuser_init(void *vectors)
808{
809}
810#endif
811
812#ifndef CONFIG_CPU_V7M
813static void copy_from_lma(void *vma, void *lma_start, void *lma_end)
814{
815 memcpy(vma, lma_start, lma_end - lma_start);
816}
817
818static void flush_vectors(void *vma, size_t offset, size_t size)
819{
820 unsigned long start = (unsigned long)vma + offset;
821 unsigned long end = start + size;
822
823 flush_icache_range(start, end);
824}
825
826#ifdef CONFIG_HARDEN_BRANCH_HISTORY
827int spectre_bhb_update_vectors(unsigned int method)
828{
829 extern char __vectors_bhb_bpiall_start[], __vectors_bhb_bpiall_end[];
830 extern char __vectors_bhb_loop8_start[], __vectors_bhb_loop8_end[];
831 void *vec_start, *vec_end;
832
833 if (system_state >= SYSTEM_FREEING_INITMEM) {
834 pr_err("CPU%u: Spectre BHB workaround too late - system vulnerable\n",
835 smp_processor_id());
836 return SPECTRE_VULNERABLE;
837 }
838
839 switch (method) {
840 case SPECTRE_V2_METHOD_LOOP8:
841 vec_start = __vectors_bhb_loop8_start;
842 vec_end = __vectors_bhb_loop8_end;
843 break;
844
845 case SPECTRE_V2_METHOD_BPIALL:
846 vec_start = __vectors_bhb_bpiall_start;
847 vec_end = __vectors_bhb_bpiall_end;
848 break;
849
850 default:
851 pr_err("CPU%u: unknown Spectre BHB state %d\n",
852 smp_processor_id(), method);
853 return SPECTRE_VULNERABLE;
854 }
855
856 copy_from_lma(vectors_page, vec_start, vec_end);
857 flush_vectors(vectors_page, 0, vec_end - vec_start);
858
859 return SPECTRE_MITIGATED;
860}
861#endif
862
863void __init early_trap_init(void *vectors_base)
864{
865 extern char __stubs_start[], __stubs_end[];
866 extern char __vectors_start[], __vectors_end[];
867 unsigned i;
868
869 vectors_page = vectors_base;
870
871 /*
872 * Poison the vectors page with an undefined instruction. This
873 * instruction is chosen to be undefined for both ARM and Thumb
874 * ISAs. The Thumb version is an undefined instruction with a
875 * branch back to the undefined instruction.
876 */
877 for (i = 0; i < PAGE_SIZE / sizeof(u32); i++)
878 ((u32 *)vectors_base)[i] = 0xe7fddef1;
879
880 /*
881 * Copy the vectors, stubs and kuser helpers (in entry-armv.S)
882 * into the vector page, mapped at 0xffff0000, and ensure these
883 * are visible to the instruction stream.
884 */
885 copy_from_lma(vma: vectors_base, lma_start: __vectors_start, lma_end: __vectors_end);
886 copy_from_lma(vma: vectors_base + 0x1000, lma_start: __stubs_start, lma_end: __stubs_end);
887
888 kuser_init(vectors: vectors_base);
889
890 flush_vectors(vma: vectors_base, offset: 0, PAGE_SIZE * 2);
891}
892#else /* ifndef CONFIG_CPU_V7M */
893void __init early_trap_init(void *vectors_base)
894{
895 /*
896 * on V7-M there is no need to copy the vector table to a dedicated
897 * memory area. The address is configurable and so a table in the kernel
898 * image can be used.
899 */
900}
901#endif
902
903#ifdef CONFIG_VMAP_STACK
904
905DECLARE_PER_CPU(u8 *, irq_stack_ptr);
906
907asmlinkage DEFINE_PER_CPU(u8 *, overflow_stack_ptr);
908
909static int __init allocate_overflow_stacks(void)
910{
911 u8 *stack;
912 int cpu;
913
914 for_each_possible_cpu(cpu) {
915 stack = (u8 *)__get_free_page(GFP_KERNEL);
916 if (WARN_ON(!stack))
917 return -ENOMEM;
918 per_cpu(overflow_stack_ptr, cpu) = &stack[OVERFLOW_STACK_SIZE];
919 }
920 return 0;
921}
922early_initcall(allocate_overflow_stacks);
923
924asmlinkage void handle_bad_stack(struct pt_regs *regs)
925{
926 unsigned long tsk_stk = (unsigned long)current->stack;
927#ifdef CONFIG_IRQSTACKS
928 unsigned long irq_stk = (unsigned long)raw_cpu_read(irq_stack_ptr);
929#endif
930 unsigned long ovf_stk = (unsigned long)raw_cpu_read(overflow_stack_ptr);
931
932 console_verbose();
933 pr_emerg("Insufficient stack space to handle exception!");
934
935 pr_emerg("Task stack: [0x%08lx..0x%08lx]\n",
936 tsk_stk, tsk_stk + THREAD_SIZE);
937#ifdef CONFIG_IRQSTACKS
938 pr_emerg("IRQ stack: [0x%08lx..0x%08lx]\n",
939 irq_stk - THREAD_SIZE, irq_stk);
940#endif
941 pr_emerg("Overflow stack: [0x%08lx..0x%08lx]\n",
942 ovf_stk - OVERFLOW_STACK_SIZE, ovf_stk);
943
944 die("kernel stack overflow", regs, 0);
945}
946
947#ifndef CONFIG_ARM_LPAE
948/*
949 * Normally, we rely on the logic in do_translation_fault() to update stale PMD
950 * entries covering the vmalloc space in a task's page tables when it first
951 * accesses the region in question. Unfortunately, this is not sufficient when
952 * the task stack resides in the vmalloc region, as do_translation_fault() is a
953 * C function that needs a stack to run.
954 *
955 * So we need to ensure that these PMD entries are up to date *before* the MM
956 * switch. As we already have some logic in the MM switch path that takes care
957 * of this, let's trigger it by bumping the counter every time the core vmalloc
958 * code modifies a PMD entry in the vmalloc region. Use release semantics on
959 * the store so that other CPUs observing the counter's new value are
960 * guaranteed to see the updated page table entries as well.
961 */
962void arch_sync_kernel_mappings(unsigned long start, unsigned long end)
963{
964 if (start < VMALLOC_END && end > VMALLOC_START)
965 atomic_inc_return_release(v: &init_mm.context.vmalloc_seq);
966}
967#endif
968#endif
969

Provided by KDAB

Privacy Policy
Improve your Profiling and Debugging skills
Find out more

source code of linux/arch/arm/kernel/traps.c