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1/*
2 * Based on arch/arm/kernel/traps.c
3 *
4 * Copyright (C) 1995-2009 Russell King
5 * Copyright (C) 2012 ARM Ltd.
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 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 */
19
20#include <linux/bug.h>
21#include <linux/signal.h>
22#include <linux/personality.h>
23#include <linux/kallsyms.h>
24#include <linux/spinlock.h>
25#include <linux/uaccess.h>
26#include <linux/hardirq.h>
27#include <linux/kdebug.h>
28#include <linux/module.h>
29#include <linux/kexec.h>
30#include <linux/delay.h>
31#include <linux/init.h>
32#include <linux/sched.h>
33#include <linux/syscalls.h>
34
35#include <asm/atomic.h>
36#include <asm/bug.h>
37#include <asm/debug-monitors.h>
38#include <asm/esr.h>
39#include <asm/insn.h>
40#include <asm/traps.h>
41#include <asm/stacktrace.h>
42#include <asm/exception.h>
43#include <asm/system_misc.h>
44
45static const char *handler[]= {
46 "Synchronous Abort",
47 "IRQ",
48 "FIQ",
49 "Error"
50};
51
52int show_unhandled_signals = 1;
53
54/*
55 * Dump out the contents of some memory nicely...
56 */
57static void dump_mem(const char *lvl, const char *str, unsigned long bottom,
58 unsigned long top, bool compat)
59{
60 unsigned long first;
61 mm_segment_t fs;
62 int i;
63 unsigned int width = compat ? 4 : 8;
64
65 /*
66 * We need to switch to kernel mode so that we can use __get_user
67 * to safely read from kernel space. Note that we now dump the
68 * code first, just in case the backtrace kills us.
69 */
70 fs = get_fs();
71 set_fs(KERNEL_DS);
72
73 printk("%s%s(0x%016lx to 0x%016lx)\n", lvl, str, bottom, top);
74
75 for (first = bottom & ~31; first < top; first += 32) {
76 unsigned long p;
77 char str[sizeof(" 12345678") * 8 + 1];
78
79 memset(str, ' ', sizeof(str));
80 str[sizeof(str) - 1] = '\0';
81
82 for (p = first, i = 0; i < (32 / width)
83 && p < top; i++, p += width) {
84 if (p >= bottom && p < top) {
85 unsigned long val;
86
87 if (width == 8) {
88 if (__get_user(val, (unsigned long *)p) == 0)
89 sprintf(str + i * 17, " %016lx", val);
90 else
91 sprintf(str + i * 17, " ????????????????");
92 } else {
93 if (__get_user(val, (unsigned int *)p) == 0)
94 sprintf(str + i * 9, " %08lx", val);
95 else
96 sprintf(str + i * 9, " ????????");
97 }
98 }
99 }
100 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
101 }
102
103 set_fs(fs);
104}
105
106static void dump_backtrace_entry(unsigned long where)
107{
108 /*
109 * Note that 'where' can have a physical address, but it's not handled.
110 */
111 print_ip_sym(where);
112}
113
114static void dump_instr(const char *lvl, struct pt_regs *regs)
115{
116 unsigned long addr = instruction_pointer(regs);
117 mm_segment_t fs;
118 char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
119 int i;
120
121 /*
122 * We need to switch to kernel mode so that we can use __get_user
123 * to safely read from kernel space. Note that we now dump the
124 * code first, just in case the backtrace kills us.
125 */
126 fs = get_fs();
127 set_fs(KERNEL_DS);
128
129 for (i = -4; i < 1; i++) {
130 unsigned int val, bad;
131
132 bad = __get_user(val, &((u32 *)addr)[i]);
133
134 if (!bad)
135 p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
136 else {
137 p += sprintf(p, "bad PC value");
138 break;
139 }
140 }
141 printk("%sCode: %s\n", lvl, str);
142
143 set_fs(fs);
144}
145
146static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
147{
148 struct stackframe frame;
149 unsigned long irq_stack_ptr;
150 int skip;
151
152 /*
153 * Switching between stacks is valid when tracing current and in
154 * non-preemptible context.
155 */
156 if (tsk == current && !preemptible())
157 irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
158 else
159 irq_stack_ptr = 0;
160
161 pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
162
163 if (!tsk)
164 tsk = current;
165
166 if (tsk == current) {
167 frame.fp = (unsigned long)__builtin_frame_address(0);
168 frame.sp = current_stack_pointer;
169 frame.pc = (unsigned long)dump_backtrace;
170 } else {
171 /*
172 * task blocked in __switch_to
173 */
174 frame.fp = thread_saved_fp(tsk);
175 frame.sp = thread_saved_sp(tsk);
176 frame.pc = thread_saved_pc(tsk);
177 }
178#ifdef CONFIG_FUNCTION_GRAPH_TRACER
179 frame.graph = tsk->curr_ret_stack;
180#endif
181
182 skip = !!regs;
183 printk("Call trace:\n");
184 while (1) {
185 unsigned long where = frame.pc;
186 unsigned long stack;
187 int ret;
188
189 /* skip until specified stack frame */
190 if (!skip) {
191 dump_backtrace_entry(where);
192 } else if (frame.fp == regs->regs[29]) {
193 skip = 0;
194 /*
195 * Mostly, this is the case where this function is
196 * called in panic/abort. As exception handler's
197 * stack frame does not contain the corresponding pc
198 * at which an exception has taken place, use regs->pc
199 * instead.
200 */
201 dump_backtrace_entry(regs->pc);
202 }
203 ret = unwind_frame(tsk, &frame);
204 if (ret < 0)
205 break;
206 stack = frame.sp;
207 if (in_exception_text(where)) {
208 /*
209 * If we switched to the irq_stack before calling this
210 * exception handler, then the pt_regs will be on the
211 * task stack. The easiest way to tell is if the large
212 * pt_regs would overlap with the end of the irq_stack.
213 */
214 if (stack < irq_stack_ptr &&
215 (stack + sizeof(struct pt_regs)) > irq_stack_ptr)
216 stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
217
218 dump_mem("", "Exception stack", stack,
219 stack + sizeof(struct pt_regs), false);
220 }
221 }
222}
223
224void show_stack(struct task_struct *tsk, unsigned long *sp)
225{
226 dump_backtrace(NULL, tsk);
227 barrier();
228}
229
230#ifdef CONFIG_PREEMPT
231#define S_PREEMPT " PREEMPT"
232#else
233#define S_PREEMPT ""
234#endif
235#define S_SMP " SMP"
236
237static int __die(const char *str, int err, struct thread_info *thread,
238 struct pt_regs *regs)
239{
240 struct task_struct *tsk = thread->task;
241 static int die_counter;
242 int ret;
243
244 pr_emerg("Internal error: %s: %x [#%d]" S_PREEMPT S_SMP "\n",
245 str, err, ++die_counter);
246
247 /* trap and error numbers are mostly meaningless on ARM */
248 ret = notify_die(DIE_OOPS, str, regs, err, 0, SIGSEGV);
249 if (ret == NOTIFY_STOP)
250 return ret;
251
252 print_modules();
253 __show_regs(regs);
254 pr_emerg("Process %.*s (pid: %d, stack limit = 0x%p)\n",
255 TASK_COMM_LEN, tsk->comm, task_pid_nr(tsk), thread + 1);
256
257 if (!user_mode(regs) || in_interrupt()) {
258 dump_mem(KERN_EMERG, "Stack: ", regs->sp,
259 THREAD_SIZE + (unsigned long)task_stack_page(tsk),
260 compat_user_mode(regs));
261 dump_backtrace(regs, tsk);
262 dump_instr(KERN_EMERG, regs);
263 }
264
265 return ret;
266}
267
268static DEFINE_RAW_SPINLOCK(die_lock);
269
270/*
271 * This function is protected against re-entrancy.
272 */
273void die(const char *str, struct pt_regs *regs, int err)
274{
275 struct thread_info *thread = current_thread_info();
276 int ret;
277
278 oops_enter();
279
280 raw_spin_lock_irq(&die_lock);
281 console_verbose();
282 bust_spinlocks(1);
283 ret = __die(str, err, thread, regs);
284
285 if (regs && kexec_should_crash(thread->task))
286 crash_kexec(regs);
287
288 bust_spinlocks(0);
289 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
290 raw_spin_unlock_irq(&die_lock);
291 oops_exit();
292
293 if (in_interrupt())
294 panic("Fatal exception in interrupt");
295 if (panic_on_oops)
296 panic("Fatal exception");
297 if (ret != NOTIFY_STOP)
298 do_exit(SIGSEGV);
299}
300
301void arm64_notify_die(const char *str, struct pt_regs *regs,
302 struct siginfo *info, int err)
303{
304 if (user_mode(regs)) {
305 current->thread.fault_address = 0;
306 current->thread.fault_code = err;
307 force_sig_info(info->si_signo, info, current);
308 } else {
309 die(str, regs, err);
310 }
311}
312
313static LIST_HEAD(undef_hook);
314static DEFINE_RAW_SPINLOCK(undef_lock);
315
316void register_undef_hook(struct undef_hook *hook)
317{
318 unsigned long flags;
319
320 raw_spin_lock_irqsave(&undef_lock, flags);
321 list_add(&hook->node, &undef_hook);
322 raw_spin_unlock_irqrestore(&undef_lock, flags);
323}
324
325void unregister_undef_hook(struct undef_hook *hook)
326{
327 unsigned long flags;
328
329 raw_spin_lock_irqsave(&undef_lock, flags);
330 list_del(&hook->node);
331 raw_spin_unlock_irqrestore(&undef_lock, flags);
332}
333
334static int call_undef_hook(struct pt_regs *regs)
335{
336 struct undef_hook *hook;
337 unsigned long flags;
338 u32 instr;
339 int (*fn)(struct pt_regs *regs, u32 instr) = NULL;
340 void __user *pc = (void __user *)instruction_pointer(regs);
341
342 if (!user_mode(regs))
343 return 1;
344
345 if (compat_thumb_mode(regs)) {
346 /* 16-bit Thumb instruction */
347 if (get_user(instr, (u16 __user *)pc))
348 goto exit;
349 instr = le16_to_cpu(instr);
350 if (aarch32_insn_is_wide(instr)) {
351 u32 instr2;
352
353 if (get_user(instr2, (u16 __user *)(pc + 2)))
354 goto exit;
355 instr2 = le16_to_cpu(instr2);
356 instr = (instr << 16) | instr2;
357 }
358 } else {
359 /* 32-bit ARM instruction */
360 if (get_user(instr, (u32 __user *)pc))
361 goto exit;
362 instr = le32_to_cpu(instr);
363 }
364
365 raw_spin_lock_irqsave(&undef_lock, flags);
366 list_for_each_entry(hook, &undef_hook, node)
367 if ((instr & hook->instr_mask) == hook->instr_val &&
368 (regs->pstate & hook->pstate_mask) == hook->pstate_val)
369 fn = hook->fn;
370
371 raw_spin_unlock_irqrestore(&undef_lock, flags);
372exit:
373 return fn ? fn(regs, instr) : 1;
374}
375
376asmlinkage void __exception do_undefinstr(struct pt_regs *regs)
377{
378 siginfo_t info;
379 void __user *pc = (void __user *)instruction_pointer(regs);
380
381 /* check for AArch32 breakpoint instructions */
382 if (!aarch32_break_handler(regs))
383 return;
384
385 if (call_undef_hook(regs) == 0)
386 return;
387
388 if (unhandled_signal(current, SIGILL) && show_unhandled_signals_ratelimited()) {
389 pr_info("%s[%d]: undefined instruction: pc=%p\n",
390 current->comm, task_pid_nr(current), pc);
391 dump_instr(KERN_INFO, regs);
392 }
393
394 info.si_signo = SIGILL;
395 info.si_errno = 0;
396 info.si_code = ILL_ILLOPC;
397 info.si_addr = pc;
398
399 arm64_notify_die("Oops - undefined instruction", regs, &info, 0);
400}
401
402long compat_arm_syscall(struct pt_regs *regs);
403
404asmlinkage long do_ni_syscall(struct pt_regs *regs)
405{
406#ifdef CONFIG_COMPAT
407 long ret;
408 if (is_compat_task()) {
409 ret = compat_arm_syscall(regs);
410 if (ret != -ENOSYS)
411 return ret;
412 }
413#endif
414
415 if (show_unhandled_signals_ratelimited()) {
416 pr_info("%s[%d]: syscall %d\n", current->comm,
417 task_pid_nr(current), (int)regs->syscallno);
418 dump_instr("", regs);
419 if (user_mode(regs))
420 __show_regs(regs);
421 }
422
423 return sys_ni_syscall();
424}
425
426static const char *esr_class_str[] = {
427 [0 ... ESR_ELx_EC_MAX] = "UNRECOGNIZED EC",
428 [ESR_ELx_EC_UNKNOWN] = "Unknown/Uncategorized",
429 [ESR_ELx_EC_WFx] = "WFI/WFE",
430 [ESR_ELx_EC_CP15_32] = "CP15 MCR/MRC",
431 [ESR_ELx_EC_CP15_64] = "CP15 MCRR/MRRC",
432 [ESR_ELx_EC_CP14_MR] = "CP14 MCR/MRC",
433 [ESR_ELx_EC_CP14_LS] = "CP14 LDC/STC",
434 [ESR_ELx_EC_FP_ASIMD] = "ASIMD",
435 [ESR_ELx_EC_CP10_ID] = "CP10 MRC/VMRS",
436 [ESR_ELx_EC_CP14_64] = "CP14 MCRR/MRRC",
437 [ESR_ELx_EC_ILL] = "PSTATE.IL",
438 [ESR_ELx_EC_SVC32] = "SVC (AArch32)",
439 [ESR_ELx_EC_HVC32] = "HVC (AArch32)",
440 [ESR_ELx_EC_SMC32] = "SMC (AArch32)",
441 [ESR_ELx_EC_SVC64] = "SVC (AArch64)",
442 [ESR_ELx_EC_HVC64] = "HVC (AArch64)",
443 [ESR_ELx_EC_SMC64] = "SMC (AArch64)",
444 [ESR_ELx_EC_SYS64] = "MSR/MRS (AArch64)",
445 [ESR_ELx_EC_IMP_DEF] = "EL3 IMP DEF",
446 [ESR_ELx_EC_IABT_LOW] = "IABT (lower EL)",
447 [ESR_ELx_EC_IABT_CUR] = "IABT (current EL)",
448 [ESR_ELx_EC_PC_ALIGN] = "PC Alignment",
449 [ESR_ELx_EC_DABT_LOW] = "DABT (lower EL)",
450 [ESR_ELx_EC_DABT_CUR] = "DABT (current EL)",
451 [ESR_ELx_EC_SP_ALIGN] = "SP Alignment",
452 [ESR_ELx_EC_FP_EXC32] = "FP (AArch32)",
453 [ESR_ELx_EC_FP_EXC64] = "FP (AArch64)",
454 [ESR_ELx_EC_SERROR] = "SError",
455 [ESR_ELx_EC_BREAKPT_LOW] = "Breakpoint (lower EL)",
456 [ESR_ELx_EC_BREAKPT_CUR] = "Breakpoint (current EL)",
457 [ESR_ELx_EC_SOFTSTP_LOW] = "Software Step (lower EL)",
458 [ESR_ELx_EC_SOFTSTP_CUR] = "Software Step (current EL)",
459 [ESR_ELx_EC_WATCHPT_LOW] = "Watchpoint (lower EL)",
460 [ESR_ELx_EC_WATCHPT_CUR] = "Watchpoint (current EL)",
461 [ESR_ELx_EC_BKPT32] = "BKPT (AArch32)",
462 [ESR_ELx_EC_VECTOR32] = "Vector catch (AArch32)",
463 [ESR_ELx_EC_BRK64] = "BRK (AArch64)",
464};
465
466const char *esr_get_class_string(u32 esr)
467{
468 return esr_class_str[esr >> ESR_ELx_EC_SHIFT];
469}
470
471/*
472 * bad_mode handles the impossible case in the exception vector.
473 */
474asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr)
475{
476 siginfo_t info;
477 void __user *pc = (void __user *)instruction_pointer(regs);
478 console_verbose();
479
480 pr_crit("Bad mode in %s handler detected, code 0x%08x -- %s\n",
481 handler[reason], esr, esr_get_class_string(esr));
482 __show_regs(regs);
483
484 info.si_signo = SIGILL;
485 info.si_errno = 0;
486 info.si_code = ILL_ILLOPC;
487 info.si_addr = pc;
488
489 arm64_notify_die("Oops - bad mode", regs, &info, 0);
490}
491
492void __pte_error(const char *file, int line, unsigned long val)
493{
494 pr_err("%s:%d: bad pte %016lx.\n", file, line, val);
495}
496
497void __pmd_error(const char *file, int line, unsigned long val)
498{
499 pr_err("%s:%d: bad pmd %016lx.\n", file, line, val);
500}
501
502void __pud_error(const char *file, int line, unsigned long val)
503{
504 pr_err("%s:%d: bad pud %016lx.\n", file, line, val);
505}
506
507void __pgd_error(const char *file, int line, unsigned long val)
508{
509 pr_err("%s:%d: bad pgd %016lx.\n", file, line, val);
510}
511
512/* GENERIC_BUG traps */
513
514int is_valid_bugaddr(unsigned long addr)
515{
516 /*
517 * bug_handler() only called for BRK #BUG_BRK_IMM.
518 * So the answer is trivial -- any spurious instances with no
519 * bug table entry will be rejected by report_bug() and passed
520 * back to the debug-monitors code and handled as a fatal
521 * unexpected debug exception.
522 */
523 return 1;
524}
525
526static int bug_handler(struct pt_regs *regs, unsigned int esr)
527{
528 if (user_mode(regs))
529 return DBG_HOOK_ERROR;
530
531 switch (report_bug(regs->pc, regs)) {
532 case BUG_TRAP_TYPE_BUG:
533 die("Oops - BUG", regs, 0);
534 break;
535
536 case BUG_TRAP_TYPE_WARN:
537 /* Ideally, report_bug() should backtrace for us... but no. */
538 dump_backtrace(regs, NULL);
539 break;
540
541 default:
542 /* unknown/unrecognised bug trap type */
543 return DBG_HOOK_ERROR;
544 }
545
546 /* If thread survives, skip over the BUG instruction and continue: */
547 regs->pc += AARCH64_INSN_SIZE; /* skip BRK and resume */
548 return DBG_HOOK_HANDLED;
549}
550
551static struct break_hook bug_break_hook = {
552 .esr_val = 0xf2000000 | BUG_BRK_IMM,
553 .esr_mask = 0xffffffff,
554 .fn = bug_handler,
555};
556
557/*
558 * Initial handler for AArch64 BRK exceptions
559 * This handler only used until debug_traps_init().
560 */
561int __init early_brk64(unsigned long addr, unsigned int esr,
562 struct pt_regs *regs)
563{
564 return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
565}
566
567/* This registration must happen early, before debug_traps_init(). */
568void __init trap_init(void)
569{
570 register_break_hook(&bug_break_hook);
571}