2 * Copyright (C) 1991, 1992 Linus Torvalds
3 * Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
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/ftrace.h>
15 #include <linux/kexec.h>
16 #include <linux/bug.h>
17 #include <linux/nmi.h>
18 #include <linux/sysfs.h>
20 #include <asm/stacktrace.h>
21 #include <asm/unwind.h>
23 int panic_on_unrecovered_nmi
;
25 unsigned int code_bytes
= 64;
26 static int die_counter
;
28 bool in_task_stack(unsigned long *stack
, struct task_struct
*task
,
29 struct stack_info
*info
)
31 unsigned long *begin
= task_stack_page(task
);
32 unsigned long *end
= task_stack_page(task
) + THREAD_SIZE
;
34 if (stack
< begin
|| stack
>= end
)
37 info
->type
= STACK_TYPE_TASK
;
45 static void printk_stack_address(unsigned long address
, int reliable
,
49 printk("%s %s%pB\n", log_lvl
, reliable
? "" : "? ", (void *)address
);
52 void show_trace_log_lvl(struct task_struct
*task
, struct pt_regs
*regs
,
53 unsigned long *stack
, char *log_lvl
)
55 struct unwind_state state
;
56 struct stack_info stack_info
= {0};
57 unsigned long visit_mask
= 0;
60 printk("%sCall Trace:\n", log_lvl
);
62 unwind_start(&state
, task
, regs
, stack
);
63 stack
= stack
? : get_stack_pointer(task
, regs
);
66 * Iterate through the stacks, starting with the current stack pointer.
67 * Each stack has a pointer to the next one.
69 * x86-64 can have several stacks:
72 * - HW exception stacks (double fault, nmi, debug, mce)
74 * x86-32 can have up to three stacks:
79 for (regs
= NULL
; stack
; stack
= stack_info
.next_sp
) {
80 const char *stack_name
;
83 * If we overflowed the task stack into a guard page, jump back
84 * to the bottom of the usable stack.
86 if (task_stack_page(task
) - (void *)stack
< PAGE_SIZE
)
87 stack
= task_stack_page(task
);
89 if (get_stack_info(stack
, task
, &stack_info
, &visit_mask
))
92 stack_name
= stack_type_name(stack_info
.type
);
94 printk("%s <%s>\n", log_lvl
, stack_name
);
97 * Scan the stack, printing any text addresses we find. At the
98 * same time, follow proper stack frames with the unwinder.
100 * Addresses found during the scan which are not reported by
101 * the unwinder are considered to be additional clues which are
102 * sometimes useful for debugging and are prefixed with '?'.
103 * This also serves as a failsafe option in case the unwinder
104 * goes off in the weeds.
106 for (; stack
< stack_info
.end
; stack
++) {
107 unsigned long real_addr
;
109 unsigned long addr
= READ_ONCE_NOCHECK(*stack
);
110 unsigned long *ret_addr_p
=
111 unwind_get_return_address_ptr(&state
);
113 if (!__kernel_text_address(addr
))
117 * Don't print regs->ip again if it was already printed
118 * by __show_regs() below.
120 if (regs
&& stack
== ®s
->ip
) {
121 unwind_next_frame(&state
);
125 if (stack
== ret_addr_p
)
129 * When function graph tracing is enabled for a
130 * function, its return address on the stack is
131 * replaced with the address of an ftrace handler
132 * (return_to_handler). In that case, before printing
133 * the "real" address, we want to print the handler
134 * address as an "unreliable" hint that function graph
135 * tracing was involved.
137 real_addr
= ftrace_graph_ret_addr(task
, &graph_idx
,
139 if (real_addr
!= addr
)
140 printk_stack_address(addr
, 0, log_lvl
);
141 printk_stack_address(real_addr
, reliable
, log_lvl
);
147 * Get the next frame from the unwinder. No need to
148 * check for an error: if anything goes wrong, the rest
149 * of the addresses will just be printed as unreliable.
151 unwind_next_frame(&state
);
153 /* if the frame has entry regs, print them */
154 regs
= unwind_get_entry_regs(&state
);
156 __show_regs(regs
, 0);
160 printk("%s </%s>\n", log_lvl
, stack_name
);
164 void show_stack(struct task_struct
*task
, unsigned long *sp
)
166 task
= task
? : current
;
169 * Stack frames below this one aren't interesting. Don't show them
170 * if we're printing for %current.
172 if (!sp
&& task
== current
)
173 sp
= get_stack_pointer(current
, NULL
);
175 show_trace_log_lvl(task
, NULL
, sp
, KERN_DEFAULT
);
178 void show_stack_regs(struct pt_regs
*regs
)
180 show_trace_log_lvl(current
, regs
, NULL
, KERN_DEFAULT
);
183 static arch_spinlock_t die_lock
= __ARCH_SPIN_LOCK_UNLOCKED
;
184 static int die_owner
= -1;
185 static unsigned int die_nest_count
;
187 unsigned long oops_begin(void)
194 /* racy, but better than risking deadlock. */
195 raw_local_irq_save(flags
);
196 cpu
= smp_processor_id();
197 if (!arch_spin_trylock(&die_lock
)) {
198 if (cpu
== die_owner
)
199 /* nested oops. should stop eventually */;
201 arch_spin_lock(&die_lock
);
209 EXPORT_SYMBOL_GPL(oops_begin
);
210 NOKPROBE_SYMBOL(oops_begin
);
212 void __noreturn
rewind_stack_do_exit(int signr
);
214 void oops_end(unsigned long flags
, struct pt_regs
*regs
, int signr
)
216 if (regs
&& kexec_should_crash(current
))
221 add_taint(TAINT_DIE
, LOCKDEP_NOW_UNRELIABLE
);
224 /* Nest count reaches zero, release the lock. */
225 arch_spin_unlock(&die_lock
);
226 raw_local_irq_restore(flags
);
232 panic("Fatal exception in interrupt");
234 panic("Fatal exception");
237 * We're not going to return, but we might be on an IST stack or
238 * have very little stack space left. Rewind the stack and kill
241 rewind_stack_do_exit(signr
);
243 NOKPROBE_SYMBOL(oops_end
);
245 int __die(const char *str
, struct pt_regs
*regs
, long err
)
252 "%s: %04lx [#%d]%s%s%s%s\n", str
, err
& 0xffff, ++die_counter
,
253 IS_ENABLED(CONFIG_PREEMPT
) ? " PREEMPT" : "",
254 IS_ENABLED(CONFIG_SMP
) ? " SMP" : "",
255 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
256 IS_ENABLED(CONFIG_KASAN
) ? " KASAN" : "");
258 if (notify_die(DIE_OOPS
, str
, regs
, err
,
259 current
->thread
.trap_nr
, SIGSEGV
) == NOTIFY_STOP
)
265 if (user_mode(regs
)) {
267 ss
= regs
->ss
& 0xffff;
269 sp
= kernel_stack_pointer(regs
);
272 printk(KERN_EMERG
"EIP: %pS SS:ESP: %04x:%08lx\n",
273 (void *)regs
->ip
, ss
, sp
);
275 /* Executive summary in case the oops scrolled away */
276 printk(KERN_ALERT
"RIP: %pS RSP: %016lx\n", (void *)regs
->ip
, regs
->sp
);
280 NOKPROBE_SYMBOL(__die
);
283 * This is gone through when something in the kernel has done something bad
284 * and is about to be terminated:
286 void die(const char *str
, struct pt_regs
*regs
, long err
)
288 unsigned long flags
= oops_begin();
291 if (!user_mode(regs
))
292 report_bug(regs
->ip
, regs
);
294 if (__die(str
, regs
, err
))
296 oops_end(flags
, regs
, sig
);
299 static int __init
code_bytes_setup(char *s
)
307 ret
= kstrtoul(s
, 0, &val
);
312 if (code_bytes
> 8192)
317 __setup("code_bytes=", code_bytes_setup
);