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1/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
4 */
5#include <linux/kallsyms.h>
6#include <linux/kprobes.h>
7#include <linux/uaccess.h>
8#include <linux/utsname.h>
9#include <linux/hardirq.h>
10#include <linux/kdebug.h>
11#include <linux/module.h>
12#include <linux/ptrace.h>
13#include <linux/sched/debug.h>
14#include <linux/sched/task_stack.h>
15#include <linux/ftrace.h>
16#include <linux/kexec.h>
17#include <linux/bug.h>
18#include <linux/nmi.h>
19#include <linux/sysfs.h>
20#include <linux/kasan.h>
21
22#include <asm/cpu_entry_area.h>
23#include <asm/stacktrace.h>
24#include <asm/unwind.h>
25
26int panic_on_unrecovered_nmi;
27int panic_on_io_nmi;
28static int die_counter;
29
30static struct pt_regs exec_summary_regs;
31
32bool in_task_stack(unsigned long *stack, struct task_struct *task,
33 struct stack_info *info)
34{
35 unsigned long *begin = task_stack_page(task);
36 unsigned long *end = task_stack_page(task) + THREAD_SIZE;
37
38 if (stack < begin || stack >= end)
39 return false;
40
41 info->type = STACK_TYPE_TASK;
42 info->begin = begin;
43 info->end = end;
44 info->next_sp = NULL;
45
46 return true;
47}
48
49bool in_entry_stack(unsigned long *stack, struct stack_info *info)
50{
51 struct entry_stack *ss = cpu_entry_stack(smp_processor_id());
52
53 void *begin = ss;
54 void *end = ss + 1;
55
56 if ((void *)stack < begin || (void *)stack >= end)
57 return false;
58
59 info->type = STACK_TYPE_ENTRY;
60 info->begin = begin;
61 info->end = end;
62 info->next_sp = NULL;
63
64 return true;
65}
66
67static void printk_stack_address(unsigned long address, int reliable,
68 const char *log_lvl)
69{
70 touch_nmi_watchdog();
71 printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
72}
73
74static int copy_code(struct pt_regs *regs, u8 *buf, unsigned long src,
75 unsigned int nbytes)
76{
77 if (!user_mode(regs))
78 return copy_from_kernel_nofault(buf, (u8 *)src, nbytes);
79
80 /*
81 * Make sure userspace isn't trying to trick us into dumping kernel
82 * memory by pointing the userspace instruction pointer at it.
83 */
84 if (__chk_range_not_ok(src, nbytes, TASK_SIZE_MAX))
85 return -EINVAL;
86
87 return copy_from_user_nmi(buf, (void __user *)src, nbytes);
88}
89
90/*
91 * There are a couple of reasons for the 2/3rd prologue, courtesy of Linus:
92 *
93 * In case where we don't have the exact kernel image (which, if we did, we can
94 * simply disassemble and navigate to the RIP), the purpose of the bigger
95 * prologue is to have more context and to be able to correlate the code from
96 * the different toolchains better.
97 *
98 * In addition, it helps in recreating the register allocation of the failing
99 * kernel and thus make sense of the register dump.
100 *
101 * What is more, the additional complication of a variable length insn arch like
102 * x86 warrants having longer byte sequence before rIP so that the disassembler
103 * can "sync" up properly and find instruction boundaries when decoding the
104 * opcode bytes.
105 *
106 * Thus, the 2/3rds prologue and 64 byte OPCODE_BUFSIZE is just a random
107 * guesstimate in attempt to achieve all of the above.
108 */
109void show_opcodes(struct pt_regs *regs, const char *loglvl)
110{
111#define PROLOGUE_SIZE 42
112#define EPILOGUE_SIZE 21
113#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)
114 u8 opcodes[OPCODE_BUFSIZE];
115 unsigned long prologue = regs->ip - PROLOGUE_SIZE;
116
117 if (copy_code(regs, opcodes, prologue, sizeof(opcodes))) {
118 printk("%sCode: Bad RIP value.\n", loglvl);
119 } else {
120 printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"
121 __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes,
122 opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1);
123 }
124}
125
126void show_ip(struct pt_regs *regs, const char *loglvl)
127{
128#ifdef CONFIG_X86_32
129 printk("%sEIP: %pS\n", loglvl, (void *)regs->ip);
130#else
131 printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip);
132#endif
133 show_opcodes(regs, loglvl);
134}
135
136void show_iret_regs(struct pt_regs *regs, const char *log_lvl)
137{
138 show_ip(regs, log_lvl);
139 printk("%sRSP: %04x:%016lx EFLAGS: %08lx", log_lvl, (int)regs->ss,
140 regs->sp, regs->flags);
141}
142
143static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,
144 bool partial, const char *log_lvl)
145{
146 /*
147 * These on_stack() checks aren't strictly necessary: the unwind code
148 * has already validated the 'regs' pointer. The checks are done for
149 * ordering reasons: if the registers are on the next stack, we don't
150 * want to print them out yet. Otherwise they'll be shown as part of
151 * the wrong stack. Later, when show_trace_log_lvl() switches to the
152 * next stack, this function will be called again with the same regs so
153 * they can be printed in the right context.
154 */
155 if (!partial && on_stack(info, regs, sizeof(*regs))) {
156 __show_regs(regs, SHOW_REGS_SHORT, log_lvl);
157
158 } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
159 IRET_FRAME_SIZE)) {
160 /*
161 * When an interrupt or exception occurs in entry code, the
162 * full pt_regs might not have been saved yet. In that case
163 * just print the iret frame.
164 */
165 show_iret_regs(regs, log_lvl);
166 }
167}
168
169void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
170 unsigned long *stack, const char *log_lvl)
171{
172 struct unwind_state state;
173 struct stack_info stack_info = {0};
174 unsigned long visit_mask = 0;
175 int graph_idx = 0;
176 bool partial = false;
177
178 printk("%sCall Trace:\n", log_lvl);
179
180 unwind_start(&state, task, regs, stack);
181 stack = stack ? : get_stack_pointer(task, regs);
182 regs = unwind_get_entry_regs(&state, &partial);
183
184 /*
185 * Iterate through the stacks, starting with the current stack pointer.
186 * Each stack has a pointer to the next one.
187 *
188 * x86-64 can have several stacks:
189 * - task stack
190 * - interrupt stack
191 * - HW exception stacks (double fault, nmi, debug, mce)
192 * - entry stack
193 *
194 * x86-32 can have up to four stacks:
195 * - task stack
196 * - softirq stack
197 * - hardirq stack
198 * - entry stack
199 */
200 for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
201 const char *stack_name;
202
203 if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
204 /*
205 * We weren't on a valid stack. It's possible that
206 * we overflowed a valid stack into a guard page.
207 * See if the next page up is valid so that we can
208 * generate some kind of backtrace if this happens.
209 */
210 stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);
211 if (get_stack_info(stack, task, &stack_info, &visit_mask))
212 break;
213 }
214
215 stack_name = stack_type_name(stack_info.type);
216 if (stack_name)
217 printk("%s <%s>\n", log_lvl, stack_name);
218
219 if (regs)
220 show_regs_if_on_stack(&stack_info, regs, partial, log_lvl);
221
222 /*
223 * Scan the stack, printing any text addresses we find. At the
224 * same time, follow proper stack frames with the unwinder.
225 *
226 * Addresses found during the scan which are not reported by
227 * the unwinder are considered to be additional clues which are
228 * sometimes useful for debugging and are prefixed with '?'.
229 * This also serves as a failsafe option in case the unwinder
230 * goes off in the weeds.
231 */
232 for (; stack < stack_info.end; stack++) {
233 unsigned long real_addr;
234 int reliable = 0;
235 unsigned long addr = READ_ONCE_NOCHECK(*stack);
236 unsigned long *ret_addr_p =
237 unwind_get_return_address_ptr(&state);
238
239 if (!__kernel_text_address(addr))
240 continue;
241
242 /*
243 * Don't print regs->ip again if it was already printed
244 * by show_regs_if_on_stack().
245 */
246 if (regs && stack == ®s->ip)
247 goto next;
248
249 if (stack == ret_addr_p)
250 reliable = 1;
251
252 /*
253 * When function graph tracing is enabled for a
254 * function, its return address on the stack is
255 * replaced with the address of an ftrace handler
256 * (return_to_handler). In that case, before printing
257 * the "real" address, we want to print the handler
258 * address as an "unreliable" hint that function graph
259 * tracing was involved.
260 */
261 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
262 addr, stack);
263 if (real_addr != addr)
264 printk_stack_address(addr, 0, log_lvl);
265 printk_stack_address(real_addr, reliable, log_lvl);
266
267 if (!reliable)
268 continue;
269
270next:
271 /*
272 * Get the next frame from the unwinder. No need to
273 * check for an error: if anything goes wrong, the rest
274 * of the addresses will just be printed as unreliable.
275 */
276 unwind_next_frame(&state);
277
278 /* if the frame has entry regs, print them */
279 regs = unwind_get_entry_regs(&state, &partial);
280 if (regs)
281 show_regs_if_on_stack(&stack_info, regs, partial, log_lvl);
282 }
283
284 if (stack_name)
285 printk("%s </%s>\n", log_lvl, stack_name);
286 }
287}
288
289void show_stack(struct task_struct *task, unsigned long *sp,
290 const char *loglvl)
291{
292 task = task ? : current;
293
294 /*
295 * Stack frames below this one aren't interesting. Don't show them
296 * if we're printing for %current.
297 */
298 if (!sp && task == current)
299 sp = get_stack_pointer(current, NULL);
300
301 show_trace_log_lvl(task, NULL, sp, loglvl);
302}
303
304void show_stack_regs(struct pt_regs *regs)
305{
306 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
307}
308
309static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
310static int die_owner = -1;
311static unsigned int die_nest_count;
312
313unsigned 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}
335NOKPROBE_SYMBOL(oops_begin);
336
337void __noreturn rewind_stack_do_exit(int signr);
338
339void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
340{
341 if (regs && kexec_should_crash(current))
342 crash_kexec(regs);
343
344 bust_spinlocks(0);
345 die_owner = -1;
346 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
347 die_nest_count--;
348 if (!die_nest_count)
349 /* Nest count reaches zero, release the lock. */
350 arch_spin_unlock(&die_lock);
351 raw_local_irq_restore(flags);
352 oops_exit();
353
354 /* Executive summary in case the oops scrolled away */
355 __show_regs(&exec_summary_regs, SHOW_REGS_ALL, KERN_DEFAULT);
356
357 if (!signr)
358 return;
359 if (in_interrupt())
360 panic("Fatal exception in interrupt");
361 if (panic_on_oops)
362 panic("Fatal exception");
363
364 /*
365 * We're not going to return, but we might be on an IST stack or
366 * have very little stack space left. Rewind the stack and kill
367 * the task.
368 * Before we rewind the stack, we have to tell KASAN that we're going to
369 * reuse the task stack and that existing poisons are invalid.
370 */
371 kasan_unpoison_task_stack(current);
372 rewind_stack_do_exit(signr);
373}
374NOKPROBE_SYMBOL(oops_end);
375
376static void __die_header(const char *str, struct pt_regs *regs, long err)
377{
378 const char *pr = "";
379
380 /* Save the regs of the first oops for the executive summary later. */
381 if (!die_counter)
382 exec_summary_regs = *regs;
383
384 if (IS_ENABLED(CONFIG_PREEMPTION))
385 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
386
387 printk(KERN_DEFAULT
388 "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
389 pr,
390 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
391 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
392 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
393 IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
394 (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
395}
396NOKPROBE_SYMBOL(__die_header);
397
398static int __die_body(const char *str, struct pt_regs *regs, long err)
399{
400 show_regs(regs);
401 print_modules();
402
403 if (notify_die(DIE_OOPS, str, regs, err,
404 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
405 return 1;
406
407 return 0;
408}
409NOKPROBE_SYMBOL(__die_body);
410
411int __die(const char *str, struct pt_regs *regs, long err)
412{
413 __die_header(str, regs, err);
414 return __die_body(str, regs, err);
415}
416NOKPROBE_SYMBOL(__die);
417
418/*
419 * This is gone through when something in the kernel has done something bad
420 * and is about to be terminated:
421 */
422void die(const char *str, struct pt_regs *regs, long err)
423{
424 unsigned long flags = oops_begin();
425 int sig = SIGSEGV;
426
427 if (__die(str, regs, err))
428 sig = 0;
429 oops_end(flags, regs, sig);
430}
431
432void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr)
433{
434 unsigned long flags = oops_begin();
435 int sig = SIGSEGV;
436
437 __die_header(str, regs, err);
438 if (gp_addr)
439 kasan_non_canonical_hook(gp_addr);
440 if (__die_body(str, regs, err))
441 sig = 0;
442 oops_end(flags, regs, sig);
443}
444
445void show_regs(struct pt_regs *regs)
446{
447 enum show_regs_mode print_kernel_regs;
448
449 show_regs_print_info(KERN_DEFAULT);
450
451 print_kernel_regs = user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL;
452 __show_regs(regs, print_kernel_regs, KERN_DEFAULT);
453
454 /*
455 * When in-kernel, we also print out the stack at the time of the fault..
456 */
457 if (!user_mode(regs))
458 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
459}
1/*
2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
4 */
5#include <linux/kallsyms.h>
6#include <linux/kprobes.h>
7#include <linux/uaccess.h>
8#include <linux/utsname.h>
9#include <linux/hardirq.h>
10#include <linux/kdebug.h>
11#include <linux/module.h>
12#include <linux/ptrace.h>
13#include <linux/sched/debug.h>
14#include <linux/sched/task_stack.h>
15#include <linux/ftrace.h>
16#include <linux/kexec.h>
17#include <linux/bug.h>
18#include <linux/nmi.h>
19#include <linux/sysfs.h>
20#include <linux/kasan.h>
21
22#include <asm/cpu_entry_area.h>
23#include <asm/stacktrace.h>
24#include <asm/unwind.h>
25
26int panic_on_unrecovered_nmi;
27int panic_on_io_nmi;
28static int die_counter;
29
30static struct pt_regs exec_summary_regs;
31
32bool noinstr in_task_stack(unsigned long *stack, struct task_struct *task,
33 struct stack_info *info)
34{
35 unsigned long *begin = task_stack_page(task);
36 unsigned long *end = task_stack_page(task) + THREAD_SIZE;
37
38 if (stack < begin || stack >= end)
39 return false;
40
41 info->type = STACK_TYPE_TASK;
42 info->begin = begin;
43 info->end = end;
44 info->next_sp = NULL;
45
46 return true;
47}
48
49/* Called from get_stack_info_noinstr - so must be noinstr too */
50bool noinstr in_entry_stack(unsigned long *stack, struct stack_info *info)
51{
52 struct entry_stack *ss = cpu_entry_stack(smp_processor_id());
53
54 void *begin = ss;
55 void *end = ss + 1;
56
57 if ((void *)stack < begin || (void *)stack >= end)
58 return false;
59
60 info->type = STACK_TYPE_ENTRY;
61 info->begin = begin;
62 info->end = end;
63 info->next_sp = NULL;
64
65 return true;
66}
67
68static void printk_stack_address(unsigned long address, int reliable,
69 const char *log_lvl)
70{
71 touch_nmi_watchdog();
72 printk("%s %s%pBb\n", log_lvl, reliable ? "" : "? ", (void *)address);
73}
74
75static int copy_code(struct pt_regs *regs, u8 *buf, unsigned long src,
76 unsigned int nbytes)
77{
78 if (!user_mode(regs))
79 return copy_from_kernel_nofault(buf, (u8 *)src, nbytes);
80
81 /* The user space code from other tasks cannot be accessed. */
82 if (regs != task_pt_regs(current))
83 return -EPERM;
84 /*
85 * Make sure userspace isn't trying to trick us into dumping kernel
86 * memory by pointing the userspace instruction pointer at it.
87 */
88 if (__chk_range_not_ok(src, nbytes, TASK_SIZE_MAX))
89 return -EINVAL;
90
91 /*
92 * Even if named copy_from_user_nmi() this can be invoked from
93 * other contexts and will not try to resolve a pagefault, which is
94 * the correct thing to do here as this code can be called from any
95 * context.
96 */
97 return copy_from_user_nmi(buf, (void __user *)src, nbytes);
98}
99
100/*
101 * There are a couple of reasons for the 2/3rd prologue, courtesy of Linus:
102 *
103 * In case where we don't have the exact kernel image (which, if we did, we can
104 * simply disassemble and navigate to the RIP), the purpose of the bigger
105 * prologue is to have more context and to be able to correlate the code from
106 * the different toolchains better.
107 *
108 * In addition, it helps in recreating the register allocation of the failing
109 * kernel and thus make sense of the register dump.
110 *
111 * What is more, the additional complication of a variable length insn arch like
112 * x86 warrants having longer byte sequence before rIP so that the disassembler
113 * can "sync" up properly and find instruction boundaries when decoding the
114 * opcode bytes.
115 *
116 * Thus, the 2/3rds prologue and 64 byte OPCODE_BUFSIZE is just a random
117 * guesstimate in attempt to achieve all of the above.
118 */
119void show_opcodes(struct pt_regs *regs, const char *loglvl)
120{
121#define PROLOGUE_SIZE 42
122#define EPILOGUE_SIZE 21
123#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)
124 u8 opcodes[OPCODE_BUFSIZE];
125 unsigned long prologue = regs->ip - PROLOGUE_SIZE;
126
127 switch (copy_code(regs, opcodes, prologue, sizeof(opcodes))) {
128 case 0:
129 printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"
130 __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes,
131 opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1);
132 break;
133 case -EPERM:
134 /* No access to the user space stack of other tasks. Ignore. */
135 break;
136 default:
137 printk("%sCode: Unable to access opcode bytes at RIP 0x%lx.\n",
138 loglvl, prologue);
139 break;
140 }
141}
142
143void show_ip(struct pt_regs *regs, const char *loglvl)
144{
145#ifdef CONFIG_X86_32
146 printk("%sEIP: %pS\n", loglvl, (void *)regs->ip);
147#else
148 printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip);
149#endif
150 show_opcodes(regs, loglvl);
151}
152
153void show_iret_regs(struct pt_regs *regs, const char *log_lvl)
154{
155 show_ip(regs, log_lvl);
156 printk("%sRSP: %04x:%016lx EFLAGS: %08lx", log_lvl, (int)regs->ss,
157 regs->sp, regs->flags);
158}
159
160static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,
161 bool partial, const char *log_lvl)
162{
163 /*
164 * These on_stack() checks aren't strictly necessary: the unwind code
165 * has already validated the 'regs' pointer. The checks are done for
166 * ordering reasons: if the registers are on the next stack, we don't
167 * want to print them out yet. Otherwise they'll be shown as part of
168 * the wrong stack. Later, when show_trace_log_lvl() switches to the
169 * next stack, this function will be called again with the same regs so
170 * they can be printed in the right context.
171 */
172 if (!partial && on_stack(info, regs, sizeof(*regs))) {
173 __show_regs(regs, SHOW_REGS_SHORT, log_lvl);
174
175 } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
176 IRET_FRAME_SIZE)) {
177 /*
178 * When an interrupt or exception occurs in entry code, the
179 * full pt_regs might not have been saved yet. In that case
180 * just print the iret frame.
181 */
182 show_iret_regs(regs, log_lvl);
183 }
184}
185
186static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
187 unsigned long *stack, const char *log_lvl)
188{
189 struct unwind_state state;
190 struct stack_info stack_info = {0};
191 unsigned long visit_mask = 0;
192 int graph_idx = 0;
193 bool partial = false;
194
195 printk("%sCall Trace:\n", log_lvl);
196
197 unwind_start(&state, task, regs, stack);
198 stack = stack ? : get_stack_pointer(task, regs);
199 regs = unwind_get_entry_regs(&state, &partial);
200
201 /*
202 * Iterate through the stacks, starting with the current stack pointer.
203 * Each stack has a pointer to the next one.
204 *
205 * x86-64 can have several stacks:
206 * - task stack
207 * - interrupt stack
208 * - HW exception stacks (double fault, nmi, debug, mce)
209 * - entry stack
210 *
211 * x86-32 can have up to four stacks:
212 * - task stack
213 * - softirq stack
214 * - hardirq stack
215 * - entry stack
216 */
217 for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
218 const char *stack_name;
219
220 if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
221 /*
222 * We weren't on a valid stack. It's possible that
223 * we overflowed a valid stack into a guard page.
224 * See if the next page up is valid so that we can
225 * generate some kind of backtrace if this happens.
226 */
227 stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);
228 if (get_stack_info(stack, task, &stack_info, &visit_mask))
229 break;
230 }
231
232 stack_name = stack_type_name(stack_info.type);
233 if (stack_name)
234 printk("%s <%s>\n", log_lvl, stack_name);
235
236 if (regs)
237 show_regs_if_on_stack(&stack_info, regs, partial, log_lvl);
238
239 /*
240 * Scan the stack, printing any text addresses we find. At the
241 * same time, follow proper stack frames with the unwinder.
242 *
243 * Addresses found during the scan which are not reported by
244 * the unwinder are considered to be additional clues which are
245 * sometimes useful for debugging and are prefixed with '?'.
246 * This also serves as a failsafe option in case the unwinder
247 * goes off in the weeds.
248 */
249 for (; stack < stack_info.end; stack++) {
250 unsigned long real_addr;
251 int reliable = 0;
252 unsigned long addr = READ_ONCE_NOCHECK(*stack);
253 unsigned long *ret_addr_p =
254 unwind_get_return_address_ptr(&state);
255
256 if (!__kernel_text_address(addr))
257 continue;
258
259 /*
260 * Don't print regs->ip again if it was already printed
261 * by show_regs_if_on_stack().
262 */
263 if (regs && stack == ®s->ip)
264 goto next;
265
266 if (stack == ret_addr_p)
267 reliable = 1;
268
269 /*
270 * When function graph tracing is enabled for a
271 * function, its return address on the stack is
272 * replaced with the address of an ftrace handler
273 * (return_to_handler). In that case, before printing
274 * the "real" address, we want to print the handler
275 * address as an "unreliable" hint that function graph
276 * tracing was involved.
277 */
278 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
279 addr, stack);
280 if (real_addr != addr)
281 printk_stack_address(addr, 0, log_lvl);
282 printk_stack_address(real_addr, reliable, log_lvl);
283
284 if (!reliable)
285 continue;
286
287next:
288 /*
289 * Get the next frame from the unwinder. No need to
290 * check for an error: if anything goes wrong, the rest
291 * of the addresses will just be printed as unreliable.
292 */
293 unwind_next_frame(&state);
294
295 /* if the frame has entry regs, print them */
296 regs = unwind_get_entry_regs(&state, &partial);
297 if (regs)
298 show_regs_if_on_stack(&stack_info, regs, partial, log_lvl);
299 }
300
301 if (stack_name)
302 printk("%s </%s>\n", log_lvl, stack_name);
303 }
304}
305
306void show_stack(struct task_struct *task, unsigned long *sp,
307 const char *loglvl)
308{
309 task = task ? : current;
310
311 /*
312 * Stack frames below this one aren't interesting. Don't show them
313 * if we're printing for %current.
314 */
315 if (!sp && task == current)
316 sp = get_stack_pointer(current, NULL);
317
318 show_trace_log_lvl(task, NULL, sp, loglvl);
319}
320
321void show_stack_regs(struct pt_regs *regs)
322{
323 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
324}
325
326static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
327static int die_owner = -1;
328static unsigned int die_nest_count;
329
330unsigned long oops_begin(void)
331{
332 int cpu;
333 unsigned long flags;
334
335 oops_enter();
336
337 /* racy, but better than risking deadlock. */
338 raw_local_irq_save(flags);
339 cpu = smp_processor_id();
340 if (!arch_spin_trylock(&die_lock)) {
341 if (cpu == die_owner)
342 /* nested oops. should stop eventually */;
343 else
344 arch_spin_lock(&die_lock);
345 }
346 die_nest_count++;
347 die_owner = cpu;
348 console_verbose();
349 bust_spinlocks(1);
350 return flags;
351}
352NOKPROBE_SYMBOL(oops_begin);
353
354void __noreturn rewind_stack_do_exit(int signr);
355
356void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
357{
358 if (regs && kexec_should_crash(current))
359 crash_kexec(regs);
360
361 bust_spinlocks(0);
362 die_owner = -1;
363 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
364 die_nest_count--;
365 if (!die_nest_count)
366 /* Nest count reaches zero, release the lock. */
367 arch_spin_unlock(&die_lock);
368 raw_local_irq_restore(flags);
369 oops_exit();
370
371 /* Executive summary in case the oops scrolled away */
372 __show_regs(&exec_summary_regs, SHOW_REGS_ALL, KERN_DEFAULT);
373
374 if (!signr)
375 return;
376 if (in_interrupt())
377 panic("Fatal exception in interrupt");
378 if (panic_on_oops)
379 panic("Fatal exception");
380
381 /*
382 * We're not going to return, but we might be on an IST stack or
383 * have very little stack space left. Rewind the stack and kill
384 * the task.
385 * Before we rewind the stack, we have to tell KASAN that we're going to
386 * reuse the task stack and that existing poisons are invalid.
387 */
388 kasan_unpoison_task_stack(current);
389 rewind_stack_do_exit(signr);
390}
391NOKPROBE_SYMBOL(oops_end);
392
393static void __die_header(const char *str, struct pt_regs *regs, long err)
394{
395 const char *pr = "";
396
397 /* Save the regs of the first oops for the executive summary later. */
398 if (!die_counter)
399 exec_summary_regs = *regs;
400
401 if (IS_ENABLED(CONFIG_PREEMPTION))
402 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
403
404 printk(KERN_DEFAULT
405 "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
406 pr,
407 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
408 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
409 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
410 IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
411 (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
412}
413NOKPROBE_SYMBOL(__die_header);
414
415static int __die_body(const char *str, struct pt_regs *regs, long err)
416{
417 show_regs(regs);
418 print_modules();
419
420 if (notify_die(DIE_OOPS, str, regs, err,
421 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
422 return 1;
423
424 return 0;
425}
426NOKPROBE_SYMBOL(__die_body);
427
428int __die(const char *str, struct pt_regs *regs, long err)
429{
430 __die_header(str, regs, err);
431 return __die_body(str, regs, err);
432}
433NOKPROBE_SYMBOL(__die);
434
435/*
436 * This is gone through when something in the kernel has done something bad
437 * and is about to be terminated:
438 */
439void die(const char *str, struct pt_regs *regs, long err)
440{
441 unsigned long flags = oops_begin();
442 int sig = SIGSEGV;
443
444 if (__die(str, regs, err))
445 sig = 0;
446 oops_end(flags, regs, sig);
447}
448
449void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr)
450{
451 unsigned long flags = oops_begin();
452 int sig = SIGSEGV;
453
454 __die_header(str, regs, err);
455 if (gp_addr)
456 kasan_non_canonical_hook(gp_addr);
457 if (__die_body(str, regs, err))
458 sig = 0;
459 oops_end(flags, regs, sig);
460}
461
462void show_regs(struct pt_regs *regs)
463{
464 enum show_regs_mode print_kernel_regs;
465
466 show_regs_print_info(KERN_DEFAULT);
467
468 print_kernel_regs = user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL;
469 __show_regs(regs, print_kernel_regs, KERN_DEFAULT);
470
471 /*
472 * When in-kernel, we also print out the stack at the time of the fault..
473 */
474 if (!user_mode(regs))
475 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
476}