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 bool in_sysenter_stack(unsigned long *stack, struct stack_info *info)
48 struct tss_struct *tss = this_cpu_ptr(&cpu_tss);
50 /* Treat the canary as part of the stack for unwinding purposes. */
51 void *begin = &tss->SYSENTER_stack_canary;
52 void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack);
54 if ((void *)stack < begin || (void *)stack >= end)
57 info->type = STACK_TYPE_SYSENTER;
65 static void printk_stack_address(unsigned long address, int reliable,
69 printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
72 void show_iret_regs(struct pt_regs *regs)
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);
79 static void show_regs_safe(struct stack_info *info, struct pt_regs *regs)
81 if (on_stack(info, regs, sizeof(*regs)))
83 else if (on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
86 * When an interrupt or exception occurs in entry code, the
87 * full pt_regs might not have been saved yet. In that case
88 * just print the iret frame.
94 void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
95 unsigned long *stack, char *log_lvl)
97 struct unwind_state state;
98 struct stack_info stack_info = {0};
99 unsigned long visit_mask = 0;
102 printk("%sCall Trace:\n", log_lvl);
104 unwind_start(&state, task, regs, stack);
105 stack = stack ? : get_stack_pointer(task, regs);
108 * Iterate through the stacks, starting with the current stack pointer.
109 * Each stack has a pointer to the next one.
111 * x86-64 can have several stacks:
114 * - HW exception stacks (double fault, nmi, debug, mce)
117 * x86-32 can have up to four stacks:
123 for (regs = NULL; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
124 const char *stack_name;
126 if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
128 * We weren't on a valid stack. It's possible that
129 * we overflowed a valid stack into a guard page.
130 * See if the next page up is valid so that we can
131 * generate some kind of backtrace if this happens.
133 stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);
134 if (get_stack_info(stack, task, &stack_info, &visit_mask))
138 stack_name = stack_type_name(stack_info.type);
140 printk("%s <%s>\n", log_lvl, stack_name);
143 show_regs_safe(&stack_info, regs);
146 * Scan the stack, printing any text addresses we find. At the
147 * same time, follow proper stack frames with the unwinder.
149 * Addresses found during the scan which are not reported by
150 * the unwinder are considered to be additional clues which are
151 * sometimes useful for debugging and are prefixed with '?'.
152 * This also serves as a failsafe option in case the unwinder
153 * goes off in the weeds.
155 for (; stack < stack_info.end; stack++) {
156 unsigned long real_addr;
158 unsigned long addr = READ_ONCE_NOCHECK(*stack);
159 unsigned long *ret_addr_p =
160 unwind_get_return_address_ptr(&state);
162 if (!__kernel_text_address(addr))
166 * Don't print regs->ip again if it was already printed
167 * by show_regs_safe() below.
169 if (regs && stack == ®s->ip)
172 if (stack == ret_addr_p)
176 * When function graph tracing is enabled for a
177 * function, its return address on the stack is
178 * replaced with the address of an ftrace handler
179 * (return_to_handler). In that case, before printing
180 * the "real" address, we want to print the handler
181 * address as an "unreliable" hint that function graph
182 * tracing was involved.
184 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
186 if (real_addr != addr)
187 printk_stack_address(addr, 0, log_lvl);
188 printk_stack_address(real_addr, reliable, log_lvl);
195 * Get the next frame from the unwinder. No need to
196 * check for an error: if anything goes wrong, the rest
197 * of the addresses will just be printed as unreliable.
199 unwind_next_frame(&state);
201 /* if the frame has entry regs, print them */
202 regs = unwind_get_entry_regs(&state);
204 show_regs_safe(&stack_info, regs);
208 printk("%s </%s>\n", log_lvl, stack_name);
212 void show_stack(struct task_struct *task, unsigned long *sp)
214 task = task ? : current;
217 * Stack frames below this one aren't interesting. Don't show them
218 * if we're printing for %current.
220 if (!sp && task == current)
221 sp = get_stack_pointer(current, NULL);
223 show_trace_log_lvl(task, NULL, sp, KERN_DEFAULT);
226 void show_stack_regs(struct pt_regs *regs)
228 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
231 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
232 static int die_owner = -1;
233 static unsigned int die_nest_count;
235 unsigned long oops_begin(void)
242 /* racy, but better than risking deadlock. */
243 raw_local_irq_save(flags);
244 cpu = smp_processor_id();
245 if (!arch_spin_trylock(&die_lock)) {
246 if (cpu == die_owner)
247 /* nested oops. should stop eventually */;
249 arch_spin_lock(&die_lock);
257 EXPORT_SYMBOL_GPL(oops_begin);
258 NOKPROBE_SYMBOL(oops_begin);
260 void __noreturn rewind_stack_do_exit(int signr);
262 void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
264 if (regs && kexec_should_crash(current))
269 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
272 /* Nest count reaches zero, release the lock. */
273 arch_spin_unlock(&die_lock);
274 raw_local_irq_restore(flags);
280 panic("Fatal exception in interrupt");
282 panic("Fatal exception");
285 * We're not going to return, but we might be on an IST stack or
286 * have very little stack space left. Rewind the stack and kill
289 rewind_stack_do_exit(signr);
291 NOKPROBE_SYMBOL(oops_end);
293 int __die(const char *str, struct pt_regs *regs, long err)
300 "%s: %04lx [#%d]%s%s%s%s\n", str, err & 0xffff, ++die_counter,
301 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
302 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
303 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
304 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "");
306 if (notify_die(DIE_OOPS, str, regs, err,
307 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
313 if (user_mode(regs)) {
317 sp = kernel_stack_pointer(regs);
320 printk(KERN_EMERG "EIP: %pS SS:ESP: %04x:%08lx\n",
321 (void *)regs->ip, ss, sp);
323 /* Executive summary in case the oops scrolled away */
324 printk(KERN_ALERT "RIP: %pS RSP: %016lx\n", (void *)regs->ip, regs->sp);
328 NOKPROBE_SYMBOL(__die);
331 * This is gone through when something in the kernel has done something bad
332 * and is about to be terminated:
334 void die(const char *str, struct pt_regs *regs, long err)
336 unsigned long flags = oops_begin();
339 if (__die(str, regs, err))
341 oops_end(flags, regs, sig);
344 static int __init code_bytes_setup(char *s)
352 ret = kstrtoul(s, 0, &val);
357 if (code_bytes > 8192)
362 __setup("code_bytes=", code_bytes_setup);