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
22 int panic_on_unrecovered_nmi;
23 int panic_on_io_nmi;
24 unsigned int code_bytes = 64;
25 int kstack_depth_to_print = 3 * STACKSLOTS_PER_LINE;
26 static int die_counter;
27
in_task_stack(unsigned long * stack,struct task_struct * task,struct stack_info * info)28 bool in_task_stack(unsigned long *stack, struct task_struct *task,
29 struct stack_info *info)
30 {
31 unsigned long *begin = task_stack_page(task);
32 unsigned long *end = task_stack_page(task) + THREAD_SIZE;
33
34 if (stack < begin || stack >= end)
35 return false;
36
37 info->type = STACK_TYPE_TASK;
38 info->begin = begin;
39 info->end = end;
40 info->next_sp = NULL;
41
42 return true;
43 }
44
printk_stack_address(unsigned long address,int reliable,char * log_lvl)45 static void printk_stack_address(unsigned long address, int reliable,
46 char *log_lvl)
47 {
48 touch_nmi_watchdog();
49 printk("%s [<%p>] %s%pB\n",
50 log_lvl, (void *)address, reliable ? "" : "? ",
51 (void *)address);
52 }
53
printk_address(unsigned long address)54 void printk_address(unsigned long address)
55 {
56 pr_cont(" [<%p>] %pS\n", (void *)address, (void *)address);
57 }
58
show_trace_log_lvl(struct task_struct * task,struct pt_regs * regs,unsigned long * stack,char * log_lvl)59 void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
60 unsigned long *stack, char *log_lvl)
61 {
62 struct unwind_state state;
63 struct stack_info stack_info = {0};
64 unsigned long visit_mask = 0;
65 int graph_idx = 0;
66
67 printk("%sCall Trace:\n", log_lvl);
68
69 unwind_start(&state, task, regs, stack);
70
71 /*
72 * Iterate through the stacks, starting with the current stack pointer.
73 * Each stack has a pointer to the next one.
74 *
75 * x86-64 can have several stacks:
76 * - task stack
77 * - interrupt stack
78 * - HW exception stacks (double fault, nmi, debug, mce)
79 *
80 * x86-32 can have up to three stacks:
81 * - task stack
82 * - softirq stack
83 * - hardirq stack
84 */
85 for (; stack; stack = stack_info.next_sp) {
86 const char *str_begin, *str_end;
87
88 /*
89 * If we overflowed the task stack into a guard page, jump back
90 * to the bottom of the usable stack.
91 */
92 if (task_stack_page(task) - (void *)stack < PAGE_SIZE)
93 stack = task_stack_page(task);
94
95 if (get_stack_info(stack, task, &stack_info, &visit_mask))
96 break;
97
98 stack_type_str(stack_info.type, &str_begin, &str_end);
99 if (str_begin)
100 printk("%s <%s> ", log_lvl, str_begin);
101
102 /*
103 * Scan the stack, printing any text addresses we find. At the
104 * same time, follow proper stack frames with the unwinder.
105 *
106 * Addresses found during the scan which are not reported by
107 * the unwinder are considered to be additional clues which are
108 * sometimes useful for debugging and are prefixed with '?'.
109 * This also serves as a failsafe option in case the unwinder
110 * goes off in the weeds.
111 */
112 for (; stack < stack_info.end; stack++) {
113 unsigned long real_addr;
114 int reliable = 0;
115 unsigned long addr = READ_ONCE_NOCHECK(*stack);
116 unsigned long *ret_addr_p =
117 unwind_get_return_address_ptr(&state);
118
119 if (!__kernel_text_address(addr))
120 continue;
121
122 if (stack == ret_addr_p)
123 reliable = 1;
124
125 /*
126 * When function graph tracing is enabled for a
127 * function, its return address on the stack is
128 * replaced with the address of an ftrace handler
129 * (return_to_handler). In that case, before printing
130 * the "real" address, we want to print the handler
131 * address as an "unreliable" hint that function graph
132 * tracing was involved.
133 */
134 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
135 addr, stack);
136 if (real_addr != addr)
137 printk_stack_address(addr, 0, log_lvl);
138 printk_stack_address(real_addr, reliable, log_lvl);
139
140 if (!reliable)
141 continue;
142
143 /*
144 * Get the next frame from the unwinder. No need to
145 * check for an error: if anything goes wrong, the rest
146 * of the addresses will just be printed as unreliable.
147 */
148 unwind_next_frame(&state);
149 }
150
151 if (str_end)
152 printk("%s <%s> ", log_lvl, str_end);
153 }
154 }
155
show_stack(struct task_struct * task,unsigned long * sp)156 void show_stack(struct task_struct *task, unsigned long *sp)
157 {
158 task = task ? : current;
159
160 /*
161 * Stack frames below this one aren't interesting. Don't show them
162 * if we're printing for %current.
163 */
164 if (!sp && task == current)
165 sp = get_stack_pointer(current, NULL);
166
167 show_stack_log_lvl(task, NULL, sp, "");
168 }
169
show_stack_regs(struct pt_regs * regs)170 void show_stack_regs(struct pt_regs *regs)
171 {
172 show_stack_log_lvl(current, regs, NULL, "");
173 }
174
175 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
176 static int die_owner = -1;
177 static unsigned int die_nest_count;
178
oops_begin(void)179 unsigned long oops_begin(void)
180 {
181 int cpu;
182 unsigned long flags;
183
184 oops_enter();
185
186 /* racy, but better than risking deadlock. */
187 raw_local_irq_save(flags);
188 cpu = smp_processor_id();
189 if (!arch_spin_trylock(&die_lock)) {
190 if (cpu == die_owner)
191 /* nested oops. should stop eventually */;
192 else
193 arch_spin_lock(&die_lock);
194 }
195 die_nest_count++;
196 die_owner = cpu;
197 console_verbose();
198 bust_spinlocks(1);
199 return flags;
200 }
201 EXPORT_SYMBOL_GPL(oops_begin);
202 NOKPROBE_SYMBOL(oops_begin);
203
204 void __noreturn rewind_stack_do_exit(int signr);
205
oops_end(unsigned long flags,struct pt_regs * regs,int signr)206 void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
207 {
208 if (regs && kexec_should_crash(current))
209 crash_kexec(regs);
210
211 bust_spinlocks(0);
212 die_owner = -1;
213 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
214 die_nest_count--;
215 if (!die_nest_count)
216 /* Nest count reaches zero, release the lock. */
217 arch_spin_unlock(&die_lock);
218 raw_local_irq_restore(flags);
219 oops_exit();
220
221 if (!signr)
222 return;
223 if (in_interrupt())
224 panic("Fatal exception in interrupt");
225 if (panic_on_oops)
226 panic("Fatal exception");
227
228 /*
229 * We're not going to return, but we might be on an IST stack or
230 * have very little stack space left. Rewind the stack and kill
231 * the task.
232 */
233 rewind_stack_do_exit(signr);
234 }
235 NOKPROBE_SYMBOL(oops_end);
236
__die(const char * str,struct pt_regs * regs,long err)237 int __die(const char *str, struct pt_regs *regs, long err)
238 {
239 #ifdef CONFIG_X86_32
240 unsigned short ss;
241 unsigned long sp;
242 #endif
243 printk(KERN_DEFAULT
244 "%s: %04lx [#%d]%s%s%s%s\n", str, err & 0xffff, ++die_counter,
245 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
246 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
247 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
248 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "");
249
250 if (notify_die(DIE_OOPS, str, regs, err,
251 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
252 return 1;
253
254 print_modules();
255 show_regs(regs);
256 #ifdef CONFIG_X86_32
257 if (user_mode(regs)) {
258 sp = regs->sp;
259 ss = regs->ss & 0xffff;
260 } else {
261 sp = kernel_stack_pointer(regs);
262 savesegment(ss, ss);
263 }
264 printk(KERN_EMERG "EIP: [<%08lx>] ", regs->ip);
265 print_symbol("%s", regs->ip);
266 printk(" SS:ESP %04x:%08lx\n", ss, sp);
267 #else
268 /* Executive summary in case the oops scrolled away */
269 printk(KERN_ALERT "RIP ");
270 printk_address(regs->ip);
271 printk(" RSP <%016lx>\n", regs->sp);
272 #endif
273 return 0;
274 }
275 NOKPROBE_SYMBOL(__die);
276
277 /*
278 * This is gone through when something in the kernel has done something bad
279 * and is about to be terminated:
280 */
die(const char * str,struct pt_regs * regs,long err)281 void die(const char *str, struct pt_regs *regs, long err)
282 {
283 unsigned long flags = oops_begin();
284 int sig = SIGSEGV;
285
286 if (!user_mode(regs))
287 report_bug(regs->ip, regs);
288
289 if (__die(str, regs, err))
290 sig = 0;
291 oops_end(flags, regs, sig);
292 }
293
kstack_setup(char * s)294 static int __init kstack_setup(char *s)
295 {
296 ssize_t ret;
297 unsigned long val;
298
299 if (!s)
300 return -EINVAL;
301
302 ret = kstrtoul(s, 0, &val);
303 if (ret)
304 return ret;
305 kstack_depth_to_print = val;
306 return 0;
307 }
308 early_param("kstack", kstack_setup);
309
code_bytes_setup(char * s)310 static int __init code_bytes_setup(char *s)
311 {
312 ssize_t ret;
313 unsigned long val;
314
315 if (!s)
316 return -EINVAL;
317
318 ret = kstrtoul(s, 0, &val);
319 if (ret)
320 return ret;
321
322 code_bytes = val;
323 if (code_bytes > 8192)
324 code_bytes = 8192;
325
326 return 1;
327 }
328 __setup("code_bytes=", code_bytes_setup);
329