mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race
[linux/fpc-iii.git] / arch / x86 / kernel / dumpstack.c
blob224de37821e4ed74ae7d1a4a1f17f848b5584832
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>
22 #include <asm/cpu_entry_area.h>
23 #include <asm/stacktrace.h>
24 #include <asm/unwind.h>
26 int panic_on_unrecovered_nmi;
27 int panic_on_io_nmi;
28 unsigned int code_bytes = 64;
29 static int die_counter;
31 bool in_task_stack(unsigned long *stack, struct task_struct *task,
32 struct stack_info *info)
34 unsigned long *begin = task_stack_page(task);
35 unsigned long *end = task_stack_page(task) + THREAD_SIZE;
37 if (stack < begin || stack >= end)
38 return false;
40 info->type = STACK_TYPE_TASK;
41 info->begin = begin;
42 info->end = end;
43 info->next_sp = NULL;
45 return true;
48 bool in_entry_stack(unsigned long *stack, struct stack_info *info)
50 struct entry_stack *ss = cpu_entry_stack(smp_processor_id());
52 void *begin = ss;
53 void *end = ss + 1;
55 if ((void *)stack < begin || (void *)stack >= end)
56 return false;
58 info->type = STACK_TYPE_ENTRY;
59 info->begin = begin;
60 info->end = end;
61 info->next_sp = NULL;
63 return true;
66 static void printk_stack_address(unsigned long address, int reliable,
67 char *log_lvl)
69 touch_nmi_watchdog();
70 printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
73 void show_iret_regs(struct pt_regs *regs)
75 printk(KERN_DEFAULT "RIP: %04x:%pS\n", (int)regs->cs, (void *)regs->ip);
76 printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss,
77 regs->sp, regs->flags);
80 static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,
81 bool partial)
84 * These on_stack() checks aren't strictly necessary: the unwind code
85 * has already validated the 'regs' pointer. The checks are done for
86 * ordering reasons: if the registers are on the next stack, we don't
87 * want to print them out yet. Otherwise they'll be shown as part of
88 * the wrong stack. Later, when show_trace_log_lvl() switches to the
89 * next stack, this function will be called again with the same regs so
90 * they can be printed in the right context.
92 if (!partial && on_stack(info, regs, sizeof(*regs))) {
93 __show_regs(regs, 0);
95 } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
96 IRET_FRAME_SIZE)) {
98 * When an interrupt or exception occurs in entry code, the
99 * full pt_regs might not have been saved yet. In that case
100 * just print the iret frame.
102 show_iret_regs(regs);
106 void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
107 unsigned long *stack, char *log_lvl)
109 struct unwind_state state;
110 struct stack_info stack_info = {0};
111 unsigned long visit_mask = 0;
112 int graph_idx = 0;
113 bool partial = false;
115 printk("%sCall Trace:\n", log_lvl);
117 unwind_start(&state, task, regs, stack);
118 stack = stack ? : get_stack_pointer(task, regs);
119 regs = unwind_get_entry_regs(&state, &partial);
122 * Iterate through the stacks, starting with the current stack pointer.
123 * Each stack has a pointer to the next one.
125 * x86-64 can have several stacks:
126 * - task stack
127 * - interrupt stack
128 * - HW exception stacks (double fault, nmi, debug, mce)
129 * - entry stack
131 * x86-32 can have up to four stacks:
132 * - task stack
133 * - softirq stack
134 * - hardirq stack
135 * - entry stack
137 for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
138 const char *stack_name;
140 if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
142 * We weren't on a valid stack. It's possible that
143 * we overflowed a valid stack into a guard page.
144 * See if the next page up is valid so that we can
145 * generate some kind of backtrace if this happens.
147 stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);
148 if (get_stack_info(stack, task, &stack_info, &visit_mask))
149 break;
152 stack_name = stack_type_name(stack_info.type);
153 if (stack_name)
154 printk("%s <%s>\n", log_lvl, stack_name);
156 if (regs)
157 show_regs_if_on_stack(&stack_info, regs, partial);
160 * Scan the stack, printing any text addresses we find. At the
161 * same time, follow proper stack frames with the unwinder.
163 * Addresses found during the scan which are not reported by
164 * the unwinder are considered to be additional clues which are
165 * sometimes useful for debugging and are prefixed with '?'.
166 * This also serves as a failsafe option in case the unwinder
167 * goes off in the weeds.
169 for (; stack < stack_info.end; stack++) {
170 unsigned long real_addr;
171 int reliable = 0;
172 unsigned long addr = READ_ONCE_NOCHECK(*stack);
173 unsigned long *ret_addr_p =
174 unwind_get_return_address_ptr(&state);
176 if (!__kernel_text_address(addr))
177 continue;
180 * Don't print regs->ip again if it was already printed
181 * by show_regs_if_on_stack().
183 if (regs && stack == &regs->ip)
184 goto next;
186 if (stack == ret_addr_p)
187 reliable = 1;
190 * When function graph tracing is enabled for a
191 * function, its return address on the stack is
192 * replaced with the address of an ftrace handler
193 * (return_to_handler). In that case, before printing
194 * the "real" address, we want to print the handler
195 * address as an "unreliable" hint that function graph
196 * tracing was involved.
198 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
199 addr, stack);
200 if (real_addr != addr)
201 printk_stack_address(addr, 0, log_lvl);
202 printk_stack_address(real_addr, reliable, log_lvl);
204 if (!reliable)
205 continue;
207 next:
209 * Get the next frame from the unwinder. No need to
210 * check for an error: if anything goes wrong, the rest
211 * of the addresses will just be printed as unreliable.
213 unwind_next_frame(&state);
215 /* if the frame has entry regs, print them */
216 regs = unwind_get_entry_regs(&state, &partial);
217 if (regs)
218 show_regs_if_on_stack(&stack_info, regs, partial);
221 if (stack_name)
222 printk("%s </%s>\n", log_lvl, stack_name);
226 void show_stack(struct task_struct *task, unsigned long *sp)
228 task = task ? : current;
231 * Stack frames below this one aren't interesting. Don't show them
232 * if we're printing for %current.
234 if (!sp && task == current)
235 sp = get_stack_pointer(current, NULL);
237 show_trace_log_lvl(task, NULL, sp, KERN_DEFAULT);
240 void show_stack_regs(struct pt_regs *regs)
242 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
245 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
246 static int die_owner = -1;
247 static unsigned int die_nest_count;
249 unsigned long oops_begin(void)
251 int cpu;
252 unsigned long flags;
254 oops_enter();
256 /* racy, but better than risking deadlock. */
257 raw_local_irq_save(flags);
258 cpu = smp_processor_id();
259 if (!arch_spin_trylock(&die_lock)) {
260 if (cpu == die_owner)
261 /* nested oops. should stop eventually */;
262 else
263 arch_spin_lock(&die_lock);
265 die_nest_count++;
266 die_owner = cpu;
267 console_verbose();
268 bust_spinlocks(1);
269 return flags;
271 EXPORT_SYMBOL_GPL(oops_begin);
272 NOKPROBE_SYMBOL(oops_begin);
274 void __noreturn rewind_stack_do_exit(int signr);
276 void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
278 if (regs && kexec_should_crash(current))
279 crash_kexec(regs);
281 bust_spinlocks(0);
282 die_owner = -1;
283 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
284 die_nest_count--;
285 if (!die_nest_count)
286 /* Nest count reaches zero, release the lock. */
287 arch_spin_unlock(&die_lock);
288 raw_local_irq_restore(flags);
289 oops_exit();
291 if (!signr)
292 return;
293 if (in_interrupt())
294 panic("Fatal exception in interrupt");
295 if (panic_on_oops)
296 panic("Fatal exception");
299 * We're not going to return, but we might be on an IST stack or
300 * have very little stack space left. Rewind the stack and kill
301 * the task.
302 * Before we rewind the stack, we have to tell KASAN that we're going to
303 * reuse the task stack and that existing poisons are invalid.
305 kasan_unpoison_task_stack(current);
306 rewind_stack_do_exit(signr);
308 NOKPROBE_SYMBOL(oops_end);
310 int __die(const char *str, struct pt_regs *regs, long err)
312 #ifdef CONFIG_X86_32
313 unsigned short ss;
314 unsigned long sp;
315 #endif
316 printk(KERN_DEFAULT
317 "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
318 IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
319 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
320 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
321 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
322 IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
323 (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
325 if (notify_die(DIE_OOPS, str, regs, err,
326 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
327 return 1;
329 print_modules();
330 show_regs(regs);
331 #ifdef CONFIG_X86_32
332 if (user_mode(regs)) {
333 sp = regs->sp;
334 ss = regs->ss;
335 } else {
336 sp = kernel_stack_pointer(regs);
337 savesegment(ss, ss);
339 printk(KERN_EMERG "EIP: %pS SS:ESP: %04x:%08lx\n",
340 (void *)regs->ip, ss, sp);
341 #else
342 /* Executive summary in case the oops scrolled away */
343 printk(KERN_ALERT "RIP: %pS RSP: %016lx\n", (void *)regs->ip, regs->sp);
344 #endif
345 return 0;
347 NOKPROBE_SYMBOL(__die);
350 * This is gone through when something in the kernel has done something bad
351 * and is about to be terminated:
353 void die(const char *str, struct pt_regs *regs, long err)
355 unsigned long flags = oops_begin();
356 int sig = SIGSEGV;
358 if (__die(str, regs, err))
359 sig = 0;
360 oops_end(flags, regs, sig);
363 static int __init code_bytes_setup(char *s)
365 ssize_t ret;
366 unsigned long val;
368 if (!s)
369 return -EINVAL;
371 ret = kstrtoul(s, 0, &val);
372 if (ret)
373 return ret;
375 code_bytes = val;
376 if (code_bytes > 8192)
377 code_bytes = 8192;
379 return 1;
381 __setup("code_bytes=", code_bytes_setup);