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/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>
21 #include <asm/stacktrace.h>
22 #include <asm/unwind.h>
24 int panic_on_unrecovered_nmi
;
26 unsigned int code_bytes
= 64;
27 static int die_counter
;
29 bool in_task_stack(unsigned long *stack
, struct task_struct
*task
,
30 struct stack_info
*info
)
32 unsigned long *begin
= task_stack_page(task
);
33 unsigned long *end
= task_stack_page(task
) + THREAD_SIZE
;
35 if (stack
< begin
|| stack
>= end
)
38 info
->type
= STACK_TYPE_TASK
;
46 static void printk_stack_address(unsigned long address
, int reliable
,
50 printk("%s %s%pB\n", log_lvl
, reliable
? "" : "? ", (void *)address
);
53 void show_trace_log_lvl(struct task_struct
*task
, struct pt_regs
*regs
,
54 unsigned long *stack
, char *log_lvl
)
56 struct unwind_state state
;
57 struct stack_info stack_info
= {0};
58 unsigned long visit_mask
= 0;
61 printk("%sCall Trace:\n", log_lvl
);
63 unwind_start(&state
, task
, regs
, stack
);
64 stack
= stack
? : get_stack_pointer(task
, regs
);
67 * Iterate through the stacks, starting with the current stack pointer.
68 * Each stack has a pointer to the next one.
70 * x86-64 can have several stacks:
73 * - HW exception stacks (double fault, nmi, debug, mce)
75 * x86-32 can have up to three stacks:
80 for (regs
= NULL
; stack
; stack
= stack_info
.next_sp
) {
81 const char *stack_name
;
84 * If we overflowed the task stack into a guard page, jump back
85 * to the bottom of the usable stack.
87 if (task_stack_page(task
) - (void *)stack
< PAGE_SIZE
)
88 stack
= task_stack_page(task
);
90 if (get_stack_info(stack
, task
, &stack_info
, &visit_mask
))
93 stack_name
= stack_type_name(stack_info
.type
);
95 printk("%s <%s>\n", log_lvl
, stack_name
);
98 * Scan the stack, printing any text addresses we find. At the
99 * same time, follow proper stack frames with the unwinder.
101 * Addresses found during the scan which are not reported by
102 * the unwinder are considered to be additional clues which are
103 * sometimes useful for debugging and are prefixed with '?'.
104 * This also serves as a failsafe option in case the unwinder
105 * goes off in the weeds.
107 for (; stack
< stack_info
.end
; stack
++) {
108 unsigned long real_addr
;
110 unsigned long addr
= READ_ONCE_NOCHECK(*stack
);
111 unsigned long *ret_addr_p
=
112 unwind_get_return_address_ptr(&state
);
114 if (!__kernel_text_address(addr
))
118 * Don't print regs->ip again if it was already printed
119 * by __show_regs() below.
121 if (regs
&& stack
== ®s
->ip
) {
122 unwind_next_frame(&state
);
126 if (stack
== ret_addr_p
)
130 * When function graph tracing is enabled for a
131 * function, its return address on the stack is
132 * replaced with the address of an ftrace handler
133 * (return_to_handler). In that case, before printing
134 * the "real" address, we want to print the handler
135 * address as an "unreliable" hint that function graph
136 * tracing was involved.
138 real_addr
= ftrace_graph_ret_addr(task
, &graph_idx
,
140 if (real_addr
!= addr
)
141 printk_stack_address(addr
, 0, log_lvl
);
142 printk_stack_address(real_addr
, reliable
, log_lvl
);
148 * Get the next frame from the unwinder. No need to
149 * check for an error: if anything goes wrong, the rest
150 * of the addresses will just be printed as unreliable.
152 unwind_next_frame(&state
);
154 /* if the frame has entry regs, print them */
155 regs
= unwind_get_entry_regs(&state
);
157 __show_regs(regs
, 0);
161 printk("%s </%s>\n", log_lvl
, stack_name
);
165 void show_stack(struct task_struct
*task
, unsigned long *sp
)
167 task
= task
? : current
;
170 * Stack frames below this one aren't interesting. Don't show them
171 * if we're printing for %current.
173 if (!sp
&& task
== current
)
174 sp
= get_stack_pointer(current
, NULL
);
176 show_trace_log_lvl(task
, NULL
, sp
, KERN_DEFAULT
);
179 void show_stack_regs(struct pt_regs
*regs
)
181 show_trace_log_lvl(current
, regs
, NULL
, KERN_DEFAULT
);
184 static arch_spinlock_t die_lock
= __ARCH_SPIN_LOCK_UNLOCKED
;
185 static int die_owner
= -1;
186 static unsigned int die_nest_count
;
188 unsigned long oops_begin(void)
195 /* racy, but better than risking deadlock. */
196 raw_local_irq_save(flags
);
197 cpu
= smp_processor_id();
198 if (!arch_spin_trylock(&die_lock
)) {
199 if (cpu
== die_owner
)
200 /* nested oops. should stop eventually */;
202 arch_spin_lock(&die_lock
);
210 EXPORT_SYMBOL_GPL(oops_begin
);
211 NOKPROBE_SYMBOL(oops_begin
);
213 void __noreturn
rewind_stack_do_exit(int signr
);
215 void oops_end(unsigned long flags
, struct pt_regs
*regs
, int signr
)
217 if (regs
&& kexec_should_crash(current
))
222 add_taint(TAINT_DIE
, LOCKDEP_NOW_UNRELIABLE
);
225 /* Nest count reaches zero, release the lock. */
226 arch_spin_unlock(&die_lock
);
227 raw_local_irq_restore(flags
);
233 panic("Fatal exception in interrupt");
235 panic("Fatal exception");
238 * We're not going to return, but we might be on an IST stack or
239 * have very little stack space left. Rewind the stack and kill
242 rewind_stack_do_exit(signr
);
244 NOKPROBE_SYMBOL(oops_end
);
246 int __die(const char *str
, struct pt_regs
*regs
, long err
)
253 "%s: %04lx [#%d]%s%s%s%s\n", str
, err
& 0xffff, ++die_counter
,
254 IS_ENABLED(CONFIG_PREEMPT
) ? " PREEMPT" : "",
255 IS_ENABLED(CONFIG_SMP
) ? " SMP" : "",
256 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
257 IS_ENABLED(CONFIG_KASAN
) ? " KASAN" : "");
259 if (notify_die(DIE_OOPS
, str
, regs
, err
,
260 current
->thread
.trap_nr
, SIGSEGV
) == NOTIFY_STOP
)
266 if (user_mode(regs
)) {
268 ss
= regs
->ss
& 0xffff;
270 sp
= kernel_stack_pointer(regs
);
273 printk(KERN_EMERG
"EIP: %pS SS:ESP: %04x:%08lx\n",
274 (void *)regs
->ip
, ss
, sp
);
276 /* Executive summary in case the oops scrolled away */
277 printk(KERN_ALERT
"RIP: %pS RSP: %016lx\n", (void *)regs
->ip
, regs
->sp
);
281 NOKPROBE_SYMBOL(__die
);
284 * This is gone through when something in the kernel has done something bad
285 * and is about to be terminated:
287 void die(const char *str
, struct pt_regs
*regs
, long err
)
289 unsigned long flags
= oops_begin();
292 if (!user_mode(regs
))
293 report_bug(regs
->ip
, regs
);
295 if (__die(str
, regs
, err
))
297 oops_end(flags
, regs
, sig
);
300 static int __init
code_bytes_setup(char *s
)
308 ret
= kstrtoul(s
, 0, &val
);
313 if (code_bytes
> 8192)
318 __setup("code_bytes=", code_bytes_setup
);