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Linux/arch/arm64/kernel/traps.c

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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 
 45 static const char *handler[]= {
 46         "Synchronous Abort",
 47         "IRQ",
 48         "FIQ",
 49         "Error"
 50 };
 51 
 52 int show_unhandled_signals = 1;
 53 
 54 /*
 55  * Dump out the contents of some memory nicely...
 56  */
 57 static 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.
 68          */
 69         fs = get_fs();
 70         set_fs(KERNEL_DS);
 71 
 72         printk("%s%s(0x%016lx to 0x%016lx)\n", lvl, str, bottom, top);
 73 
 74         for (first = bottom & ~31; first < top; first += 32) {
 75                 unsigned long p;
 76                 char str[sizeof(" 12345678") * 8 + 1];
 77 
 78                 memset(str, ' ', sizeof(str));
 79                 str[sizeof(str) - 1] = '\0';
 80 
 81                 for (p = first, i = 0; i < (32 / width)
 82                                         && p < top; i++, p += width) {
 83                         if (p >= bottom && p < top) {
 84                                 unsigned long val;
 85 
 86                                 if (width == 8) {
 87                                         if (__get_user(val, (unsigned long *)p) == 0)
 88                                                 sprintf(str + i * 17, " %016lx", val);
 89                                         else
 90                                                 sprintf(str + i * 17, " ????????????????");
 91                                 } else {
 92                                         if (__get_user(val, (unsigned int *)p) == 0)
 93                                                 sprintf(str + i * 9, " %08lx", val);
 94                                         else
 95                                                 sprintf(str + i * 9, " ????????");
 96                                 }
 97                         }
 98                 }
 99                 printk("%s%04lx:%s\n", lvl, first & 0xffff, str);
100         }
101 
102         set_fs(fs);
103 }
104 
105 static void dump_backtrace_entry(unsigned long where)
106 {
107         /*
108          * Note that 'where' can have a physical address, but it's not handled.
109          */
110         print_ip_sym(where);
111 }
112 
113 static void __dump_instr(const char *lvl, struct pt_regs *regs)
114 {
115         unsigned long addr = instruction_pointer(regs);
116         char str[sizeof("00000000 ") * 5 + 2 + 1], *p = str;
117         int i;
118 
119         for (i = -4; i < 1; i++) {
120                 unsigned int val, bad;
121 
122                 bad = __get_user(val, &((u32 *)addr)[i]);
123 
124                 if (!bad)
125                         p += sprintf(p, i == 0 ? "(%08x) " : "%08x ", val);
126                 else {
127                         p += sprintf(p, "bad PC value");
128                         break;
129                 }
130         }
131         printk("%sCode: %s\n", lvl, str);
132 }
133 
134 static void dump_instr(const char *lvl, struct pt_regs *regs)
135 {
136         if (!user_mode(regs)) {
137                 mm_segment_t fs = get_fs();
138                 set_fs(KERNEL_DS);
139                 __dump_instr(lvl, regs);
140                 set_fs(fs);
141         } else {
142                 __dump_instr(lvl, regs);
143         }
144 }
145 
146 static 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         pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
153 
154         if (!tsk)
155                 tsk = current;
156 
157         /*
158          * Switching between stacks is valid when tracing current and in
159          * non-preemptible context.
160          */
161         if (tsk == current && !preemptible())
162                 irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
163         else
164                 irq_stack_ptr = 0;
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 
224 void 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 
237 static 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 
268 static DEFINE_RAW_SPINLOCK(die_lock);
269 
270 /*
271  * This function is protected against re-entrancy.
272  */
273 void 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 
301 void 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 
313 static LIST_HEAD(undef_hook);
314 static DEFINE_RAW_SPINLOCK(undef_lock);
315 
316 void 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 
325 void 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 
334 static 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);
372 exit:
373         return fn ? fn(regs, instr) : 1;
374 }
375 
376 asmlinkage 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 
402 long compat_arm_syscall(struct pt_regs *regs);
403 
404 asmlinkage 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 
426 static 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 
466 const 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  */
474 asmlinkage 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 on CPU%d, code 0x%08x -- %s\n",
481                 handler[reason], smp_processor_id(), esr,
482                 esr_get_class_string(esr));
483         __show_regs(regs);
484 
485         info.si_signo = SIGILL;
486         info.si_errno = 0;
487         info.si_code  = ILL_ILLOPC;
488         info.si_addr  = pc;
489 
490         arm64_notify_die("Oops - bad mode", regs, &info, 0);
491 }
492 
493 void __pte_error(const char *file, int line, unsigned long val)
494 {
495         pr_err("%s:%d: bad pte %016lx.\n", file, line, val);
496 }
497 
498 void __pmd_error(const char *file, int line, unsigned long val)
499 {
500         pr_err("%s:%d: bad pmd %016lx.\n", file, line, val);
501 }
502 
503 void __pud_error(const char *file, int line, unsigned long val)
504 {
505         pr_err("%s:%d: bad pud %016lx.\n", file, line, val);
506 }
507 
508 void __pgd_error(const char *file, int line, unsigned long val)
509 {
510         pr_err("%s:%d: bad pgd %016lx.\n", file, line, val);
511 }
512 
513 /* GENERIC_BUG traps */
514 
515 int is_valid_bugaddr(unsigned long addr)
516 {
517         /*
518          * bug_handler() only called for BRK #BUG_BRK_IMM.
519          * So the answer is trivial -- any spurious instances with no
520          * bug table entry will be rejected by report_bug() and passed
521          * back to the debug-monitors code and handled as a fatal
522          * unexpected debug exception.
523          */
524         return 1;
525 }
526 
527 static int bug_handler(struct pt_regs *regs, unsigned int esr)
528 {
529         if (user_mode(regs))
530                 return DBG_HOOK_ERROR;
531 
532         switch (report_bug(regs->pc, regs)) {
533         case BUG_TRAP_TYPE_BUG:
534                 die("Oops - BUG", regs, 0);
535                 break;
536 
537         case BUG_TRAP_TYPE_WARN:
538                 /* Ideally, report_bug() should backtrace for us... but no. */
539                 dump_backtrace(regs, NULL);
540                 break;
541 
542         default:
543                 /* unknown/unrecognised bug trap type */
544                 return DBG_HOOK_ERROR;
545         }
546 
547         /* If thread survives, skip over the BUG instruction and continue: */
548         regs->pc += AARCH64_INSN_SIZE;  /* skip BRK and resume */
549         return DBG_HOOK_HANDLED;
550 }
551 
552 static struct break_hook bug_break_hook = {
553         .esr_val = 0xf2000000 | BUG_BRK_IMM,
554         .esr_mask = 0xffffffff,
555         .fn = bug_handler,
556 };
557 
558 /*
559  * Initial handler for AArch64 BRK exceptions
560  * This handler only used until debug_traps_init().
561  */
562 int __init early_brk64(unsigned long addr, unsigned int esr,
563                 struct pt_regs *regs)
564 {
565         return bug_handler(regs, esr) != DBG_HOOK_HANDLED;
566 }
567 
568 /* This registration must happen early, before debug_traps_init(). */
569 void __init trap_init(void)
570 {
571         register_break_hook(&bug_break_hook);
572 }
573 

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