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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 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 /*
86 * Even if named copy_from_user_nmi() this can be invoked from
87 * other contexts and will not try to resolve a pagefault, which is
88 * the correct thing to do here as this code can be called from any
89 * context.
90 */
91 return copy_from_user_nmi(buf, (void __user *)src, nbytes);
92}
93
94/*
95 * There are a couple of reasons for the 2/3rd prologue, courtesy of Linus:
96 *
97 * In case where we don't have the exact kernel image (which, if we did, we can
98 * simply disassemble and navigate to the RIP), the purpose of the bigger
99 * prologue is to have more context and to be able to correlate the code from
100 * the different toolchains better.
101 *
102 * In addition, it helps in recreating the register allocation of the failing
103 * kernel and thus make sense of the register dump.
104 *
105 * What is more, the additional complication of a variable length insn arch like
106 * x86 warrants having longer byte sequence before rIP so that the disassembler
107 * can "sync" up properly and find instruction boundaries when decoding the
108 * opcode bytes.
109 *
110 * Thus, the 2/3rds prologue and 64 byte OPCODE_BUFSIZE is just a random
111 * guesstimate in attempt to achieve all of the above.
112 */
113void show_opcodes(struct pt_regs *regs, const char *loglvl)
114{
115#define PROLOGUE_SIZE 42
116#define EPILOGUE_SIZE 21
117#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)
118 u8 opcodes[OPCODE_BUFSIZE];
119 unsigned long prologue = regs->ip - PROLOGUE_SIZE;
120
121 switch (copy_code(regs, opcodes, prologue, sizeof(opcodes))) {
122 case 0:
123 printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"
124 __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes,
125 opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1);
126 break;
127 case -EPERM:
128 /* No access to the user space stack of other tasks. Ignore. */
129 break;
130 default:
131 printk("%sCode: Unable to access opcode bytes at 0x%lx.\n",
132 loglvl, prologue);
133 break;
134 }
135}
136
137void show_ip(struct pt_regs *regs, const char *loglvl)
138{
139#ifdef CONFIG_X86_32
140 printk("%sEIP: %pS\n", loglvl, (void *)regs->ip);
141#else
142 printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip);
143#endif
144 show_opcodes(regs, loglvl);
145}
146
147void show_iret_regs(struct pt_regs *regs, const char *log_lvl)
148{
149 show_ip(regs, log_lvl);
150 printk("%sRSP: %04x:%016lx EFLAGS: %08lx", log_lvl, (int)regs->ss,
151 regs->sp, regs->flags);
152}
153
154static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,
155 bool partial, const char *log_lvl)
156{
157 /*
158 * These on_stack() checks aren't strictly necessary: the unwind code
159 * has already validated the 'regs' pointer. The checks are done for
160 * ordering reasons: if the registers are on the next stack, we don't
161 * want to print them out yet. Otherwise they'll be shown as part of
162 * the wrong stack. Later, when show_trace_log_lvl() switches to the
163 * next stack, this function will be called again with the same regs so
164 * they can be printed in the right context.
165 */
166 if (!partial && on_stack(info, regs, sizeof(*regs))) {
167 __show_regs(regs, SHOW_REGS_SHORT, log_lvl);
168
169 } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
170 IRET_FRAME_SIZE)) {
171 /*
172 * When an interrupt or exception occurs in entry code, the
173 * full pt_regs might not have been saved yet. In that case
174 * just print the iret frame.
175 */
176 show_iret_regs(regs, log_lvl);
177 }
178}
179
180/*
181 * This function reads pointers from the stack and dereferences them. The
182 * pointers may not have their KMSAN shadow set up properly, which may result
183 * in false positive reports. Disable instrumentation to avoid those.
184 */
185__no_kmsan_checks
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 regs = unwind_get_entry_regs(&state, &partial);
199
200 /*
201 * Iterate through the stacks, starting with the current stack pointer.
202 * Each stack has a pointer to the next one.
203 *
204 * x86-64 can have several stacks:
205 * - task stack
206 * - interrupt stack
207 * - HW exception stacks (double fault, nmi, debug, mce)
208 * - entry stack
209 *
210 * x86-32 can have up to four stacks:
211 * - task stack
212 * - softirq stack
213 * - hardirq stack
214 * - entry stack
215 */
216 for (stack = stack ?: get_stack_pointer(task, regs);
217 stack;
218 stack = stack_info.next_sp) {
219 const char *stack_name;
220
221 stack = PTR_ALIGN(stack, sizeof(long));
222
223 if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
224 /*
225 * We weren't on a valid stack. It's possible that
226 * we overflowed a valid stack into a guard page.
227 * See if the next page up is valid so that we can
228 * generate some kind of backtrace if this happens.
229 */
230 stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);
231 if (get_stack_info(stack, task, &stack_info, &visit_mask))
232 break;
233 }
234
235 stack_name = stack_type_name(stack_info.type);
236 if (stack_name)
237 printk("%s <%s>\n", log_lvl, stack_name);
238
239 if (regs)
240 show_regs_if_on_stack(&stack_info, regs, partial, log_lvl);
241
242 /*
243 * Scan the stack, printing any text addresses we find. At the
244 * same time, follow proper stack frames with the unwinder.
245 *
246 * Addresses found during the scan which are not reported by
247 * the unwinder are considered to be additional clues which are
248 * sometimes useful for debugging and are prefixed with '?'.
249 * This also serves as a failsafe option in case the unwinder
250 * goes off in the weeds.
251 */
252 for (; stack < stack_info.end; stack++) {
253 unsigned long real_addr;
254 int reliable = 0;
255 unsigned long addr = READ_ONCE_NOCHECK(*stack);
256 unsigned long *ret_addr_p =
257 unwind_get_return_address_ptr(&state);
258
259 if (!__kernel_text_address(addr))
260 continue;
261
262 /*
263 * Don't print regs->ip again if it was already printed
264 * by show_regs_if_on_stack().
265 */
266 if (regs && stack == ®s->ip)
267 goto next;
268
269 if (stack == ret_addr_p)
270 reliable = 1;
271
272 /*
273 * When function graph tracing is enabled for a
274 * function, its return address on the stack is
275 * replaced with the address of an ftrace handler
276 * (return_to_handler). In that case, before printing
277 * the "real" address, we want to print the handler
278 * address as an "unreliable" hint that function graph
279 * tracing was involved.
280 */
281 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
282 addr, stack);
283 if (real_addr != addr)
284 printk_stack_address(addr, 0, log_lvl);
285 printk_stack_address(real_addr, reliable, log_lvl);
286
287 if (!reliable)
288 continue;
289
290next:
291 /*
292 * Get the next frame from the unwinder. No need to
293 * check for an error: if anything goes wrong, the rest
294 * of the addresses will just be printed as unreliable.
295 */
296 unwind_next_frame(&state);
297
298 /* if the frame has entry regs, print them */
299 regs = unwind_get_entry_regs(&state, &partial);
300 if (regs)
301 show_regs_if_on_stack(&stack_info, regs, partial, log_lvl);
302 }
303
304 if (stack_name)
305 printk("%s </%s>\n", log_lvl, stack_name);
306 }
307}
308
309void show_stack(struct task_struct *task, unsigned long *sp,
310 const char *loglvl)
311{
312 task = task ? : current;
313
314 /*
315 * Stack frames below this one aren't interesting. Don't show them
316 * if we're printing for %current.
317 */
318 if (!sp && task == current)
319 sp = get_stack_pointer(current, NULL);
320
321 show_trace_log_lvl(task, NULL, sp, loglvl);
322}
323
324void show_stack_regs(struct pt_regs *regs)
325{
326 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
327}
328
329static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
330static int die_owner = -1;
331static unsigned int die_nest_count;
332
333unsigned long oops_begin(void)
334{
335 int cpu;
336 unsigned long flags;
337
338 oops_enter();
339
340 /* racy, but better than risking deadlock. */
341 raw_local_irq_save(flags);
342 cpu = smp_processor_id();
343 if (!arch_spin_trylock(&die_lock)) {
344 if (cpu == die_owner)
345 /* nested oops. should stop eventually */;
346 else
347 arch_spin_lock(&die_lock);
348 }
349 die_nest_count++;
350 die_owner = cpu;
351 console_verbose();
352 bust_spinlocks(1);
353 return flags;
354}
355NOKPROBE_SYMBOL(oops_begin);
356
357void __noreturn rewind_stack_and_make_dead(int signr);
358
359void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
360{
361 if (regs && kexec_should_crash(current))
362 crash_kexec(regs);
363
364 bust_spinlocks(0);
365 die_owner = -1;
366 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
367 die_nest_count--;
368 if (!die_nest_count)
369 /* Nest count reaches zero, release the lock. */
370 arch_spin_unlock(&die_lock);
371 raw_local_irq_restore(flags);
372 oops_exit();
373
374 /* Executive summary in case the oops scrolled away */
375 __show_regs(&exec_summary_regs, SHOW_REGS_ALL, KERN_DEFAULT);
376
377 if (!signr)
378 return;
379 if (in_interrupt())
380 panic("Fatal exception in interrupt");
381 if (panic_on_oops)
382 panic("Fatal exception");
383
384 /*
385 * We're not going to return, but we might be on an IST stack or
386 * have very little stack space left. Rewind the stack and kill
387 * the task.
388 * Before we rewind the stack, we have to tell KASAN that we're going to
389 * reuse the task stack and that existing poisons are invalid.
390 */
391 kasan_unpoison_task_stack(current);
392 rewind_stack_and_make_dead(signr);
393}
394NOKPROBE_SYMBOL(oops_end);
395
396static void __die_header(const char *str, struct pt_regs *regs, long err)
397{
398 const char *pr = "";
399
400 /* Save the regs of the first oops for the executive summary later. */
401 if (!die_counter)
402 exec_summary_regs = *regs;
403
404 if (IS_ENABLED(CONFIG_PREEMPTION))
405 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
406
407 printk(KERN_DEFAULT
408 "Oops: %s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff,
409 ++die_counter, pr,
410 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
411 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
412 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
413 IS_ENABLED(CONFIG_MITIGATION_PAGE_TABLE_ISOLATION) ?
414 (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
415}
416NOKPROBE_SYMBOL(__die_header);
417
418static int __die_body(const char *str, struct pt_regs *regs, long err)
419{
420 show_regs(regs);
421 print_modules();
422
423 if (notify_die(DIE_OOPS, str, regs, err,
424 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
425 return 1;
426
427 return 0;
428}
429NOKPROBE_SYMBOL(__die_body);
430
431int __die(const char *str, struct pt_regs *regs, long err)
432{
433 __die_header(str, regs, err);
434 return __die_body(str, regs, err);
435}
436NOKPROBE_SYMBOL(__die);
437
438/*
439 * This is gone through when something in the kernel has done something bad
440 * and is about to be terminated:
441 */
442void die(const char *str, struct pt_regs *regs, long err)
443{
444 unsigned long flags = oops_begin();
445 int sig = SIGSEGV;
446
447 if (__die(str, regs, err))
448 sig = 0;
449 oops_end(flags, regs, sig);
450}
451
452void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr)
453{
454 unsigned long flags = oops_begin();
455 int sig = SIGSEGV;
456
457 __die_header(str, regs, err);
458 if (gp_addr)
459 kasan_non_canonical_hook(gp_addr);
460 if (__die_body(str, regs, err))
461 sig = 0;
462 oops_end(flags, regs, sig);
463}
464
465void show_regs(struct pt_regs *regs)
466{
467 enum show_regs_mode print_kernel_regs;
468
469 show_regs_print_info(KERN_DEFAULT);
470
471 print_kernel_regs = user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL;
472 __show_regs(regs, print_kernel_regs, KERN_DEFAULT);
473
474 /*
475 * When in-kernel, we also print out the stack at the time of the fault..
476 */
477 if (!user_mode(regs))
478 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
479}
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 char *log_lvl)
69{
70 touch_nmi_watchdog();
71 printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
72}
73
74/*
75 * There are a couple of reasons for the 2/3rd prologue, courtesy of Linus:
76 *
77 * In case where we don't have the exact kernel image (which, if we did, we can
78 * simply disassemble and navigate to the RIP), the purpose of the bigger
79 * prologue is to have more context and to be able to correlate the code from
80 * the different toolchains better.
81 *
82 * In addition, it helps in recreating the register allocation of the failing
83 * kernel and thus make sense of the register dump.
84 *
85 * What is more, the additional complication of a variable length insn arch like
86 * x86 warrants having longer byte sequence before rIP so that the disassembler
87 * can "sync" up properly and find instruction boundaries when decoding the
88 * opcode bytes.
89 *
90 * Thus, the 2/3rds prologue and 64 byte OPCODE_BUFSIZE is just a random
91 * guesstimate in attempt to achieve all of the above.
92 */
93void show_opcodes(struct pt_regs *regs, const char *loglvl)
94{
95#define PROLOGUE_SIZE 42
96#define EPILOGUE_SIZE 21
97#define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)
98 u8 opcodes[OPCODE_BUFSIZE];
99 unsigned long prologue = regs->ip - PROLOGUE_SIZE;
100 bool bad_ip;
101
102 /*
103 * Make sure userspace isn't trying to trick us into dumping kernel
104 * memory by pointing the userspace instruction pointer at it.
105 */
106 bad_ip = user_mode(regs) &&
107 __chk_range_not_ok(prologue, OPCODE_BUFSIZE, TASK_SIZE_MAX);
108
109 if (bad_ip || probe_kernel_read(opcodes, (u8 *)prologue,
110 OPCODE_BUFSIZE)) {
111 printk("%sCode: Bad RIP value.\n", loglvl);
112 } else {
113 printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"
114 __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes,
115 opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1);
116 }
117}
118
119void show_ip(struct pt_regs *regs, const char *loglvl)
120{
121#ifdef CONFIG_X86_32
122 printk("%sEIP: %pS\n", loglvl, (void *)regs->ip);
123#else
124 printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip);
125#endif
126 show_opcodes(regs, loglvl);
127}
128
129void show_iret_regs(struct pt_regs *regs)
130{
131 show_ip(regs, KERN_DEFAULT);
132 printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss,
133 regs->sp, regs->flags);
134}
135
136static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,
137 bool partial)
138{
139 /*
140 * These on_stack() checks aren't strictly necessary: the unwind code
141 * has already validated the 'regs' pointer. The checks are done for
142 * ordering reasons: if the registers are on the next stack, we don't
143 * want to print them out yet. Otherwise they'll be shown as part of
144 * the wrong stack. Later, when show_trace_log_lvl() switches to the
145 * next stack, this function will be called again with the same regs so
146 * they can be printed in the right context.
147 */
148 if (!partial && on_stack(info, regs, sizeof(*regs))) {
149 __show_regs(regs, SHOW_REGS_SHORT);
150
151 } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
152 IRET_FRAME_SIZE)) {
153 /*
154 * When an interrupt or exception occurs in entry code, the
155 * full pt_regs might not have been saved yet. In that case
156 * just print the iret frame.
157 */
158 show_iret_regs(regs);
159 }
160}
161
162void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
163 unsigned long *stack, char *log_lvl)
164{
165 struct unwind_state state;
166 struct stack_info stack_info = {0};
167 unsigned long visit_mask = 0;
168 int graph_idx = 0;
169 bool partial = false;
170
171 printk("%sCall Trace:\n", log_lvl);
172
173 unwind_start(&state, task, regs, stack);
174 stack = stack ? : get_stack_pointer(task, regs);
175 regs = unwind_get_entry_regs(&state, &partial);
176
177 /*
178 * Iterate through the stacks, starting with the current stack pointer.
179 * Each stack has a pointer to the next one.
180 *
181 * x86-64 can have several stacks:
182 * - task stack
183 * - interrupt stack
184 * - HW exception stacks (double fault, nmi, debug, mce)
185 * - entry stack
186 *
187 * x86-32 can have up to four stacks:
188 * - task stack
189 * - softirq stack
190 * - hardirq stack
191 * - entry stack
192 */
193 for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
194 const char *stack_name;
195
196 if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
197 /*
198 * We weren't on a valid stack. It's possible that
199 * we overflowed a valid stack into a guard page.
200 * See if the next page up is valid so that we can
201 * generate some kind of backtrace if this happens.
202 */
203 stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);
204 if (get_stack_info(stack, task, &stack_info, &visit_mask))
205 break;
206 }
207
208 stack_name = stack_type_name(stack_info.type);
209 if (stack_name)
210 printk("%s <%s>\n", log_lvl, stack_name);
211
212 if (regs)
213 show_regs_if_on_stack(&stack_info, regs, partial);
214
215 /*
216 * Scan the stack, printing any text addresses we find. At the
217 * same time, follow proper stack frames with the unwinder.
218 *
219 * Addresses found during the scan which are not reported by
220 * the unwinder are considered to be additional clues which are
221 * sometimes useful for debugging and are prefixed with '?'.
222 * This also serves as a failsafe option in case the unwinder
223 * goes off in the weeds.
224 */
225 for (; stack < stack_info.end; stack++) {
226 unsigned long real_addr;
227 int reliable = 0;
228 unsigned long addr = READ_ONCE_NOCHECK(*stack);
229 unsigned long *ret_addr_p =
230 unwind_get_return_address_ptr(&state);
231
232 if (!__kernel_text_address(addr))
233 continue;
234
235 /*
236 * Don't print regs->ip again if it was already printed
237 * by show_regs_if_on_stack().
238 */
239 if (regs && stack == ®s->ip)
240 goto next;
241
242 if (stack == ret_addr_p)
243 reliable = 1;
244
245 /*
246 * When function graph tracing is enabled for a
247 * function, its return address on the stack is
248 * replaced with the address of an ftrace handler
249 * (return_to_handler). In that case, before printing
250 * the "real" address, we want to print the handler
251 * address as an "unreliable" hint that function graph
252 * tracing was involved.
253 */
254 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
255 addr, stack);
256 if (real_addr != addr)
257 printk_stack_address(addr, 0, log_lvl);
258 printk_stack_address(real_addr, reliable, log_lvl);
259
260 if (!reliable)
261 continue;
262
263next:
264 /*
265 * Get the next frame from the unwinder. No need to
266 * check for an error: if anything goes wrong, the rest
267 * of the addresses will just be printed as unreliable.
268 */
269 unwind_next_frame(&state);
270
271 /* if the frame has entry regs, print them */
272 regs = unwind_get_entry_regs(&state, &partial);
273 if (regs)
274 show_regs_if_on_stack(&stack_info, regs, partial);
275 }
276
277 if (stack_name)
278 printk("%s </%s>\n", log_lvl, stack_name);
279 }
280}
281
282void show_stack(struct task_struct *task, unsigned long *sp)
283{
284 task = task ? : current;
285
286 /*
287 * Stack frames below this one aren't interesting. Don't show them
288 * if we're printing for %current.
289 */
290 if (!sp && task == current)
291 sp = get_stack_pointer(current, NULL);
292
293 show_trace_log_lvl(task, NULL, sp, KERN_DEFAULT);
294}
295
296void show_stack_regs(struct pt_regs *regs)
297{
298 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
299}
300
301static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
302static int die_owner = -1;
303static unsigned int die_nest_count;
304
305unsigned long oops_begin(void)
306{
307 int cpu;
308 unsigned long flags;
309
310 oops_enter();
311
312 /* racy, but better than risking deadlock. */
313 raw_local_irq_save(flags);
314 cpu = smp_processor_id();
315 if (!arch_spin_trylock(&die_lock)) {
316 if (cpu == die_owner)
317 /* nested oops. should stop eventually */;
318 else
319 arch_spin_lock(&die_lock);
320 }
321 die_nest_count++;
322 die_owner = cpu;
323 console_verbose();
324 bust_spinlocks(1);
325 return flags;
326}
327NOKPROBE_SYMBOL(oops_begin);
328
329void __noreturn rewind_stack_do_exit(int signr);
330
331void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
332{
333 if (regs && kexec_should_crash(current))
334 crash_kexec(regs);
335
336 bust_spinlocks(0);
337 die_owner = -1;
338 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
339 die_nest_count--;
340 if (!die_nest_count)
341 /* Nest count reaches zero, release the lock. */
342 arch_spin_unlock(&die_lock);
343 raw_local_irq_restore(flags);
344 oops_exit();
345
346 /* Executive summary in case the oops scrolled away */
347 __show_regs(&exec_summary_regs, SHOW_REGS_ALL);
348
349 if (!signr)
350 return;
351 if (in_interrupt())
352 panic("Fatal exception in interrupt");
353 if (panic_on_oops)
354 panic("Fatal exception");
355
356 /*
357 * We're not going to return, but we might be on an IST stack or
358 * have very little stack space left. Rewind the stack and kill
359 * the task.
360 * Before we rewind the stack, we have to tell KASAN that we're going to
361 * reuse the task stack and that existing poisons are invalid.
362 */
363 kasan_unpoison_task_stack(current);
364 rewind_stack_do_exit(signr);
365}
366NOKPROBE_SYMBOL(oops_end);
367
368int __die(const char *str, struct pt_regs *regs, long err)
369{
370 const char *pr = "";
371
372 /* Save the regs of the first oops for the executive summary later. */
373 if (!die_counter)
374 exec_summary_regs = *regs;
375
376 if (IS_ENABLED(CONFIG_PREEMPTION))
377 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
378
379 printk(KERN_DEFAULT
380 "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
381 pr,
382 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
383 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
384 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
385 IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
386 (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
387
388 show_regs(regs);
389 print_modules();
390
391 if (notify_die(DIE_OOPS, str, regs, err,
392 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
393 return 1;
394
395 return 0;
396}
397NOKPROBE_SYMBOL(__die);
398
399/*
400 * This is gone through when something in the kernel has done something bad
401 * and is about to be terminated:
402 */
403void die(const char *str, struct pt_regs *regs, long err)
404{
405 unsigned long flags = oops_begin();
406 int sig = SIGSEGV;
407
408 if (__die(str, regs, err))
409 sig = 0;
410 oops_end(flags, regs, sig);
411}
412
413void show_regs(struct pt_regs *regs)
414{
415 show_regs_print_info(KERN_DEFAULT);
416
417 __show_regs(regs, user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL);
418
419 /*
420 * When in-kernel, we also print out the stack at the time of the fault..
421 */
422 if (!user_mode(regs))
423 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
424}