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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
21#include <asm/cpu_entry_area.h>
22#include <asm/stacktrace.h>
23#include <asm/unwind.h>
24
25int panic_on_unrecovered_nmi;
26int panic_on_io_nmi;
27static unsigned int code_bytes = 64;
28static int die_counter;
29
30bool in_task_stack(unsigned long *stack, struct task_struct *task,
31 struct stack_info *info)
32{
33 unsigned long *begin = task_stack_page(task);
34 unsigned long *end = task_stack_page(task) + THREAD_SIZE;
35
36 if (stack < begin || stack >= end)
37 return false;
38
39 info->type = STACK_TYPE_TASK;
40 info->begin = begin;
41 info->end = end;
42 info->next_sp = NULL;
43
44 return true;
45}
46
47bool in_entry_stack(unsigned long *stack, struct stack_info *info)
48{
49 struct entry_stack *ss = cpu_entry_stack(smp_processor_id());
50
51 void *begin = ss;
52 void *end = ss + 1;
53
54 if ((void *)stack < begin || (void *)stack >= end)
55 return false;
56
57 info->type = STACK_TYPE_ENTRY;
58 info->begin = begin;
59 info->end = end;
60 info->next_sp = NULL;
61
62 return true;
63}
64
65static void printk_stack_address(unsigned long address, int reliable,
66 char *log_lvl)
67{
68 touch_nmi_watchdog();
69 printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
70}
71
72void show_iret_regs(struct pt_regs *regs)
73{
74 printk(KERN_DEFAULT "RIP: %04x:%pS\n", (int)regs->cs, (void *)regs->ip);
75 printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss,
76 regs->sp, regs->flags);
77}
78
79static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,
80 bool partial)
81{
82 /*
83 * These on_stack() checks aren't strictly necessary: the unwind code
84 * has already validated the 'regs' pointer. The checks are done for
85 * ordering reasons: if the registers are on the next stack, we don't
86 * want to print them out yet. Otherwise they'll be shown as part of
87 * the wrong stack. Later, when show_trace_log_lvl() switches to the
88 * next stack, this function will be called again with the same regs so
89 * they can be printed in the right context.
90 */
91 if (!partial && on_stack(info, regs, sizeof(*regs))) {
92 __show_regs(regs, 0);
93
94 } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
95 IRET_FRAME_SIZE)) {
96 /*
97 * When an interrupt or exception occurs in entry code, the
98 * full pt_regs might not have been saved yet. In that case
99 * just print the iret frame.
100 */
101 show_iret_regs(regs);
102 }
103}
104
105void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
106 unsigned long *stack, char *log_lvl)
107{
108 struct unwind_state state;
109 struct stack_info stack_info = {0};
110 unsigned long visit_mask = 0;
111 int graph_idx = 0;
112 bool partial = false;
113
114 printk("%sCall Trace:\n", log_lvl);
115
116 unwind_start(&state, task, regs, stack);
117 stack = stack ? : get_stack_pointer(task, regs);
118 regs = unwind_get_entry_regs(&state, &partial);
119
120 /*
121 * Iterate through the stacks, starting with the current stack pointer.
122 * Each stack has a pointer to the next one.
123 *
124 * x86-64 can have several stacks:
125 * - task stack
126 * - interrupt stack
127 * - HW exception stacks (double fault, nmi, debug, mce)
128 * - entry stack
129 *
130 * x86-32 can have up to four stacks:
131 * - task stack
132 * - softirq stack
133 * - hardirq stack
134 * - entry stack
135 */
136 for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
137 const char *stack_name;
138
139 if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
140 /*
141 * We weren't on a valid stack. It's possible that
142 * we overflowed a valid stack into a guard page.
143 * See if the next page up is valid so that we can
144 * generate some kind of backtrace if this happens.
145 */
146 stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);
147 if (get_stack_info(stack, task, &stack_info, &visit_mask))
148 break;
149 }
150
151 stack_name = stack_type_name(stack_info.type);
152 if (stack_name)
153 printk("%s <%s>\n", log_lvl, stack_name);
154
155 if (regs)
156 show_regs_if_on_stack(&stack_info, regs, partial);
157
158 /*
159 * Scan the stack, printing any text addresses we find. At the
160 * same time, follow proper stack frames with the unwinder.
161 *
162 * Addresses found during the scan which are not reported by
163 * the unwinder are considered to be additional clues which are
164 * sometimes useful for debugging and are prefixed with '?'.
165 * This also serves as a failsafe option in case the unwinder
166 * goes off in the weeds.
167 */
168 for (; stack < stack_info.end; stack++) {
169 unsigned long real_addr;
170 int reliable = 0;
171 unsigned long addr = READ_ONCE_NOCHECK(*stack);
172 unsigned long *ret_addr_p =
173 unwind_get_return_address_ptr(&state);
174
175 if (!__kernel_text_address(addr))
176 continue;
177
178 /*
179 * Don't print regs->ip again if it was already printed
180 * by show_regs_if_on_stack().
181 */
182 if (regs && stack == ®s->ip)
183 goto next;
184
185 if (stack == ret_addr_p)
186 reliable = 1;
187
188 /*
189 * When function graph tracing is enabled for a
190 * function, its return address on the stack is
191 * replaced with the address of an ftrace handler
192 * (return_to_handler). In that case, before printing
193 * the "real" address, we want to print the handler
194 * address as an "unreliable" hint that function graph
195 * tracing was involved.
196 */
197 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
198 addr, stack);
199 if (real_addr != addr)
200 printk_stack_address(addr, 0, log_lvl);
201 printk_stack_address(real_addr, reliable, log_lvl);
202
203 if (!reliable)
204 continue;
205
206next:
207 /*
208 * Get the next frame from the unwinder. No need to
209 * check for an error: if anything goes wrong, the rest
210 * of the addresses will just be printed as unreliable.
211 */
212 unwind_next_frame(&state);
213
214 /* if the frame has entry regs, print them */
215 regs = unwind_get_entry_regs(&state, &partial);
216 if (regs)
217 show_regs_if_on_stack(&stack_info, regs, partial);
218 }
219
220 if (stack_name)
221 printk("%s </%s>\n", log_lvl, stack_name);
222 }
223}
224
225void show_stack(struct task_struct *task, unsigned long *sp)
226{
227 task = task ? : current;
228
229 /*
230 * Stack frames below this one aren't interesting. Don't show them
231 * if we're printing for %current.
232 */
233 if (!sp && task == current)
234 sp = get_stack_pointer(current, NULL);
235
236 show_trace_log_lvl(task, NULL, sp, KERN_DEFAULT);
237}
238
239void show_stack_regs(struct pt_regs *regs)
240{
241 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
242}
243
244static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
245static int die_owner = -1;
246static unsigned int die_nest_count;
247
248unsigned long oops_begin(void)
249{
250 int cpu;
251 unsigned long flags;
252
253 oops_enter();
254
255 /* racy, but better than risking deadlock. */
256 raw_local_irq_save(flags);
257 cpu = smp_processor_id();
258 if (!arch_spin_trylock(&die_lock)) {
259 if (cpu == die_owner)
260 /* nested oops. should stop eventually */;
261 else
262 arch_spin_lock(&die_lock);
263 }
264 die_nest_count++;
265 die_owner = cpu;
266 console_verbose();
267 bust_spinlocks(1);
268 return flags;
269}
270EXPORT_SYMBOL_GPL(oops_begin);
271NOKPROBE_SYMBOL(oops_begin);
272
273void __noreturn rewind_stack_do_exit(int signr);
274
275void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
276{
277 if (regs && kexec_should_crash(current))
278 crash_kexec(regs);
279
280 bust_spinlocks(0);
281 die_owner = -1;
282 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
283 die_nest_count--;
284 if (!die_nest_count)
285 /* Nest count reaches zero, release the lock. */
286 arch_spin_unlock(&die_lock);
287 raw_local_irq_restore(flags);
288 oops_exit();
289
290 if (!signr)
291 return;
292 if (in_interrupt())
293 panic("Fatal exception in interrupt");
294 if (panic_on_oops)
295 panic("Fatal exception");
296
297 /*
298 * We're not going to return, but we might be on an IST stack or
299 * have very little stack space left. Rewind the stack and kill
300 * the task.
301 */
302 rewind_stack_do_exit(signr);
303}
304NOKPROBE_SYMBOL(oops_end);
305
306int __die(const char *str, struct pt_regs *regs, long err)
307{
308#ifdef CONFIG_X86_32
309 unsigned short ss;
310 unsigned long sp;
311#endif
312 printk(KERN_DEFAULT
313 "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
314 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
315 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
316 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
317 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
318 IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
319 (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
320
321 if (notify_die(DIE_OOPS, str, regs, err,
322 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
323 return 1;
324
325 print_modules();
326 show_regs(regs);
327#ifdef CONFIG_X86_32
328 if (user_mode(regs)) {
329 sp = regs->sp;
330 ss = regs->ss;
331 } else {
332 sp = kernel_stack_pointer(regs);
333 savesegment(ss, ss);
334 }
335 printk(KERN_EMERG "EIP: %pS SS:ESP: %04x:%08lx\n",
336 (void *)regs->ip, ss, sp);
337#else
338 /* Executive summary in case the oops scrolled away */
339 printk(KERN_ALERT "RIP: %pS RSP: %016lx\n", (void *)regs->ip, regs->sp);
340#endif
341 return 0;
342}
343NOKPROBE_SYMBOL(__die);
344
345/*
346 * This is gone through when something in the kernel has done something bad
347 * and is about to be terminated:
348 */
349void die(const char *str, struct pt_regs *regs, long err)
350{
351 unsigned long flags = oops_begin();
352 int sig = SIGSEGV;
353
354 if (__die(str, regs, err))
355 sig = 0;
356 oops_end(flags, regs, sig);
357}
358
359static int __init code_bytes_setup(char *s)
360{
361 ssize_t ret;
362 unsigned long val;
363
364 if (!s)
365 return -EINVAL;
366
367 ret = kstrtoul(s, 0, &val);
368 if (ret)
369 return ret;
370
371 code_bytes = val;
372 if (code_bytes > 8192)
373 code_bytes = 8192;
374
375 return 1;
376}
377__setup("code_bytes=", code_bytes_setup);
378
379void show_regs(struct pt_regs *regs)
380{
381 bool all = true;
382 int i;
383
384 show_regs_print_info(KERN_DEFAULT);
385
386 if (IS_ENABLED(CONFIG_X86_32))
387 all = !user_mode(regs);
388
389 __show_regs(regs, all);
390
391 /*
392 * When in-kernel, we also print out the stack and code at the
393 * time of the fault..
394 */
395 if (!user_mode(regs)) {
396 unsigned int code_prologue = code_bytes * 43 / 64;
397 unsigned int code_len = code_bytes;
398 unsigned char c;
399 u8 *ip;
400
401 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
402
403 printk(KERN_DEFAULT "Code: ");
404
405 ip = (u8 *)regs->ip - code_prologue;
406 if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
407 /* try starting at IP */
408 ip = (u8 *)regs->ip;
409 code_len = code_len - code_prologue + 1;
410 }
411 for (i = 0; i < code_len; i++, ip++) {
412 if (ip < (u8 *)PAGE_OFFSET ||
413 probe_kernel_address(ip, c)) {
414 pr_cont(" Bad RIP value.");
415 break;
416 }
417 if (ip == (u8 *)regs->ip)
418 pr_cont("<%02x> ", c);
419 else
420 pr_cont("%02x ", c);
421 }
422 }
423 pr_cont("\n");
424}
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/ftrace.h>
14#include <linux/kexec.h>
15#include <linux/bug.h>
16#include <linux/nmi.h>
17#include <linux/sysfs.h>
18
19#include <asm/stacktrace.h>
20#include <asm/unwind.h>
21
22int panic_on_unrecovered_nmi;
23int panic_on_io_nmi;
24unsigned int code_bytes = 64;
25static int die_counter;
26
27bool in_task_stack(unsigned long *stack, struct task_struct *task,
28 struct stack_info *info)
29{
30 unsigned long *begin = task_stack_page(task);
31 unsigned long *end = task_stack_page(task) + THREAD_SIZE;
32
33 if (stack < begin || stack >= end)
34 return false;
35
36 info->type = STACK_TYPE_TASK;
37 info->begin = begin;
38 info->end = end;
39 info->next_sp = NULL;
40
41 return true;
42}
43
44static void printk_stack_address(unsigned long address, int reliable,
45 char *log_lvl)
46{
47 touch_nmi_watchdog();
48 printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
49}
50
51void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
52 unsigned long *stack, char *log_lvl)
53{
54 struct unwind_state state;
55 struct stack_info stack_info = {0};
56 unsigned long visit_mask = 0;
57 int graph_idx = 0;
58
59 printk("%sCall Trace:\n", log_lvl);
60
61 unwind_start(&state, task, regs, stack);
62 stack = stack ? : get_stack_pointer(task, regs);
63
64 /*
65 * Iterate through the stacks, starting with the current stack pointer.
66 * Each stack has a pointer to the next one.
67 *
68 * x86-64 can have several stacks:
69 * - task stack
70 * - interrupt stack
71 * - HW exception stacks (double fault, nmi, debug, mce)
72 *
73 * x86-32 can have up to three stacks:
74 * - task stack
75 * - softirq stack
76 * - hardirq stack
77 */
78 for (regs = NULL; stack; stack = stack_info.next_sp) {
79 const char *stack_name;
80
81 /*
82 * If we overflowed the task stack into a guard page, jump back
83 * to the bottom of the usable stack.
84 */
85 if (task_stack_page(task) - (void *)stack < PAGE_SIZE)
86 stack = task_stack_page(task);
87
88 if (get_stack_info(stack, task, &stack_info, &visit_mask))
89 break;
90
91 stack_name = stack_type_name(stack_info.type);
92 if (stack_name)
93 printk("%s <%s>\n", log_lvl, stack_name);
94
95 /*
96 * Scan the stack, printing any text addresses we find. At the
97 * same time, follow proper stack frames with the unwinder.
98 *
99 * Addresses found during the scan which are not reported by
100 * the unwinder are considered to be additional clues which are
101 * sometimes useful for debugging and are prefixed with '?'.
102 * This also serves as a failsafe option in case the unwinder
103 * goes off in the weeds.
104 */
105 for (; stack < stack_info.end; stack++) {
106 unsigned long real_addr;
107 int reliable = 0;
108 unsigned long addr = READ_ONCE_NOCHECK(*stack);
109 unsigned long *ret_addr_p =
110 unwind_get_return_address_ptr(&state);
111
112 if (!__kernel_text_address(addr))
113 continue;
114
115 /*
116 * Don't print regs->ip again if it was already printed
117 * by __show_regs() below.
118 */
119 if (regs && stack == ®s->ip) {
120 unwind_next_frame(&state);
121 continue;
122 }
123
124 if (stack == ret_addr_p)
125 reliable = 1;
126
127 /*
128 * When function graph tracing is enabled for a
129 * function, its return address on the stack is
130 * replaced with the address of an ftrace handler
131 * (return_to_handler). In that case, before printing
132 * the "real" address, we want to print the handler
133 * address as an "unreliable" hint that function graph
134 * tracing was involved.
135 */
136 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
137 addr, stack);
138 if (real_addr != addr)
139 printk_stack_address(addr, 0, log_lvl);
140 printk_stack_address(real_addr, reliable, log_lvl);
141
142 if (!reliable)
143 continue;
144
145 /*
146 * Get the next frame from the unwinder. No need to
147 * check for an error: if anything goes wrong, the rest
148 * of the addresses will just be printed as unreliable.
149 */
150 unwind_next_frame(&state);
151
152 /* if the frame has entry regs, print them */
153 regs = unwind_get_entry_regs(&state);
154 if (regs)
155 __show_regs(regs, 0);
156 }
157
158 if (stack_name)
159 printk("%s </%s>\n", log_lvl, stack_name);
160 }
161}
162
163void show_stack(struct task_struct *task, unsigned long *sp)
164{
165 task = task ? : current;
166
167 /*
168 * Stack frames below this one aren't interesting. Don't show them
169 * if we're printing for %current.
170 */
171 if (!sp && task == current)
172 sp = get_stack_pointer(current, NULL);
173
174 show_trace_log_lvl(task, NULL, sp, KERN_DEFAULT);
175}
176
177void show_stack_regs(struct pt_regs *regs)
178{
179 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
180}
181
182static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
183static int die_owner = -1;
184static unsigned int die_nest_count;
185
186unsigned long oops_begin(void)
187{
188 int cpu;
189 unsigned long flags;
190
191 oops_enter();
192
193 /* racy, but better than risking deadlock. */
194 raw_local_irq_save(flags);
195 cpu = smp_processor_id();
196 if (!arch_spin_trylock(&die_lock)) {
197 if (cpu == die_owner)
198 /* nested oops. should stop eventually */;
199 else
200 arch_spin_lock(&die_lock);
201 }
202 die_nest_count++;
203 die_owner = cpu;
204 console_verbose();
205 bust_spinlocks(1);
206 return flags;
207}
208EXPORT_SYMBOL_GPL(oops_begin);
209NOKPROBE_SYMBOL(oops_begin);
210
211void __noreturn rewind_stack_do_exit(int signr);
212
213void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
214{
215 if (regs && kexec_should_crash(current))
216 crash_kexec(regs);
217
218 bust_spinlocks(0);
219 die_owner = -1;
220 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
221 die_nest_count--;
222 if (!die_nest_count)
223 /* Nest count reaches zero, release the lock. */
224 arch_spin_unlock(&die_lock);
225 raw_local_irq_restore(flags);
226 oops_exit();
227
228 if (!signr)
229 return;
230 if (in_interrupt())
231 panic("Fatal exception in interrupt");
232 if (panic_on_oops)
233 panic("Fatal exception");
234
235 /*
236 * We're not going to return, but we might be on an IST stack or
237 * have very little stack space left. Rewind the stack and kill
238 * the task.
239 */
240 rewind_stack_do_exit(signr);
241}
242NOKPROBE_SYMBOL(oops_end);
243
244int __die(const char *str, struct pt_regs *regs, long err)
245{
246#ifdef CONFIG_X86_32
247 unsigned short ss;
248 unsigned long sp;
249#endif
250 printk(KERN_DEFAULT
251 "%s: %04lx [#%d]%s%s%s%s\n", str, err & 0xffff, ++die_counter,
252 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
253 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
254 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
255 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "");
256
257 if (notify_die(DIE_OOPS, str, regs, err,
258 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
259 return 1;
260
261 print_modules();
262 show_regs(regs);
263#ifdef CONFIG_X86_32
264 if (user_mode(regs)) {
265 sp = regs->sp;
266 ss = regs->ss & 0xffff;
267 } else {
268 sp = kernel_stack_pointer(regs);
269 savesegment(ss, ss);
270 }
271 printk(KERN_EMERG "EIP: %pS SS:ESP: %04x:%08lx\n",
272 (void *)regs->ip, ss, sp);
273#else
274 /* Executive summary in case the oops scrolled away */
275 printk(KERN_ALERT "RIP: %pS RSP: %016lx\n", (void *)regs->ip, regs->sp);
276#endif
277 return 0;
278}
279NOKPROBE_SYMBOL(__die);
280
281/*
282 * This is gone through when something in the kernel has done something bad
283 * and is about to be terminated:
284 */
285void die(const char *str, struct pt_regs *regs, long err)
286{
287 unsigned long flags = oops_begin();
288 int sig = SIGSEGV;
289
290 if (!user_mode(regs))
291 report_bug(regs->ip, regs);
292
293 if (__die(str, regs, err))
294 sig = 0;
295 oops_end(flags, regs, sig);
296}
297
298static int __init code_bytes_setup(char *s)
299{
300 ssize_t ret;
301 unsigned long val;
302
303 if (!s)
304 return -EINVAL;
305
306 ret = kstrtoul(s, 0, &val);
307 if (ret)
308 return ret;
309
310 code_bytes = val;
311 if (code_bytes > 8192)
312 code_bytes = 8192;
313
314 return 1;
315}
316__setup("code_bytes=", code_bytes_setup);