arm64: dts: Revert "specify console via command line"
[linux/fpc-iii.git] / arch / x86 / kernel / dumpstack.c
blobae64ec7f752f401f970d9d3cd3e7722aeb72d60e
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 static int die_counter;
30 static struct pt_regs exec_summary_regs;
32 bool in_task_stack(unsigned long *stack, struct task_struct *task,
33 struct stack_info *info)
35 unsigned long *begin = task_stack_page(task);
36 unsigned long *end = task_stack_page(task) + THREAD_SIZE;
38 if (stack < begin || stack >= end)
39 return false;
41 info->type = STACK_TYPE_TASK;
42 info->begin = begin;
43 info->end = end;
44 info->next_sp = NULL;
46 return true;
49 bool in_entry_stack(unsigned long *stack, struct stack_info *info)
51 struct entry_stack *ss = cpu_entry_stack(smp_processor_id());
53 void *begin = ss;
54 void *end = ss + 1;
56 if ((void *)stack < begin || (void *)stack >= end)
57 return false;
59 info->type = STACK_TYPE_ENTRY;
60 info->begin = begin;
61 info->end = end;
62 info->next_sp = NULL;
64 return true;
67 static void printk_stack_address(unsigned long address, int reliable,
68 char *log_lvl)
70 touch_nmi_watchdog();
71 printk("%s %s%pB\n", log_lvl, reliable ? "" : "? ", (void *)address);
75 * There are a couple of reasons for the 2/3rd prologue, courtesy of Linus:
77 * In case where we don't have the exact kernel image (which, if we did, we can
78 * simply disassemble and navigate to the RIP), the purpose of the bigger
79 * prologue is to have more context and to be able to correlate the code from
80 * the different toolchains better.
82 * In addition, it helps in recreating the register allocation of the failing
83 * kernel and thus make sense of the register dump.
85 * What is more, the additional complication of a variable length insn arch like
86 * x86 warrants having longer byte sequence before rIP so that the disassembler
87 * can "sync" up properly and find instruction boundaries when decoding the
88 * opcode bytes.
90 * Thus, the 2/3rds prologue and 64 byte OPCODE_BUFSIZE is just a random
91 * guesstimate in attempt to achieve all of the above.
93 void show_opcodes(struct pt_regs *regs, const char *loglvl)
95 #define PROLOGUE_SIZE 42
96 #define EPILOGUE_SIZE 21
97 #define OPCODE_BUFSIZE (PROLOGUE_SIZE + 1 + EPILOGUE_SIZE)
98 u8 opcodes[OPCODE_BUFSIZE];
99 unsigned long prologue = regs->ip - PROLOGUE_SIZE;
100 bool bad_ip;
103 * Make sure userspace isn't trying to trick us into dumping kernel
104 * memory by pointing the userspace instruction pointer at it.
106 bad_ip = user_mode(regs) &&
107 __chk_range_not_ok(prologue, OPCODE_BUFSIZE, TASK_SIZE_MAX);
109 if (bad_ip || probe_kernel_read(opcodes, (u8 *)prologue,
110 OPCODE_BUFSIZE)) {
111 printk("%sCode: Bad RIP value.\n", loglvl);
112 } else {
113 printk("%sCode: %" __stringify(PROLOGUE_SIZE) "ph <%02x> %"
114 __stringify(EPILOGUE_SIZE) "ph\n", loglvl, opcodes,
115 opcodes[PROLOGUE_SIZE], opcodes + PROLOGUE_SIZE + 1);
119 void show_ip(struct pt_regs *regs, const char *loglvl)
121 #ifdef CONFIG_X86_32
122 printk("%sEIP: %pS\n", loglvl, (void *)regs->ip);
123 #else
124 printk("%sRIP: %04x:%pS\n", loglvl, (int)regs->cs, (void *)regs->ip);
125 #endif
126 show_opcodes(regs, loglvl);
129 void show_iret_regs(struct pt_regs *regs)
131 show_ip(regs, KERN_DEFAULT);
132 printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss,
133 regs->sp, regs->flags);
136 static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs,
137 bool partial)
140 * These on_stack() checks aren't strictly necessary: the unwind code
141 * has already validated the 'regs' pointer. The checks are done for
142 * ordering reasons: if the registers are on the next stack, we don't
143 * want to print them out yet. Otherwise they'll be shown as part of
144 * the wrong stack. Later, when show_trace_log_lvl() switches to the
145 * next stack, this function will be called again with the same regs so
146 * they can be printed in the right context.
148 if (!partial && on_stack(info, regs, sizeof(*regs))) {
149 __show_regs(regs, SHOW_REGS_SHORT);
151 } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET,
152 IRET_FRAME_SIZE)) {
154 * When an interrupt or exception occurs in entry code, the
155 * full pt_regs might not have been saved yet. In that case
156 * just print the iret frame.
158 show_iret_regs(regs);
162 void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
163 unsigned long *stack, char *log_lvl)
165 struct unwind_state state;
166 struct stack_info stack_info = {0};
167 unsigned long visit_mask = 0;
168 int graph_idx = 0;
169 bool partial = false;
171 printk("%sCall Trace:\n", log_lvl);
173 unwind_start(&state, task, regs, stack);
174 stack = stack ? : get_stack_pointer(task, regs);
175 regs = unwind_get_entry_regs(&state, &partial);
178 * Iterate through the stacks, starting with the current stack pointer.
179 * Each stack has a pointer to the next one.
181 * x86-64 can have several stacks:
182 * - task stack
183 * - interrupt stack
184 * - HW exception stacks (double fault, nmi, debug, mce)
185 * - entry stack
187 * x86-32 can have up to four stacks:
188 * - task stack
189 * - softirq stack
190 * - hardirq stack
191 * - entry stack
193 for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
194 const char *stack_name;
196 if (get_stack_info(stack, task, &stack_info, &visit_mask)) {
198 * We weren't on a valid stack. It's possible that
199 * we overflowed a valid stack into a guard page.
200 * See if the next page up is valid so that we can
201 * generate some kind of backtrace if this happens.
203 stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack);
204 if (get_stack_info(stack, task, &stack_info, &visit_mask))
205 break;
208 stack_name = stack_type_name(stack_info.type);
209 if (stack_name)
210 printk("%s <%s>\n", log_lvl, stack_name);
212 if (regs)
213 show_regs_if_on_stack(&stack_info, regs, partial);
216 * Scan the stack, printing any text addresses we find. At the
217 * same time, follow proper stack frames with the unwinder.
219 * Addresses found during the scan which are not reported by
220 * the unwinder are considered to be additional clues which are
221 * sometimes useful for debugging and are prefixed with '?'.
222 * This also serves as a failsafe option in case the unwinder
223 * goes off in the weeds.
225 for (; stack < stack_info.end; stack++) {
226 unsigned long real_addr;
227 int reliable = 0;
228 unsigned long addr = READ_ONCE_NOCHECK(*stack);
229 unsigned long *ret_addr_p =
230 unwind_get_return_address_ptr(&state);
232 if (!__kernel_text_address(addr))
233 continue;
236 * Don't print regs->ip again if it was already printed
237 * by show_regs_if_on_stack().
239 if (regs && stack == &regs->ip)
240 goto next;
242 if (stack == ret_addr_p)
243 reliable = 1;
246 * When function graph tracing is enabled for a
247 * function, its return address on the stack is
248 * replaced with the address of an ftrace handler
249 * (return_to_handler). In that case, before printing
250 * the "real" address, we want to print the handler
251 * address as an "unreliable" hint that function graph
252 * tracing was involved.
254 real_addr = ftrace_graph_ret_addr(task, &graph_idx,
255 addr, stack);
256 if (real_addr != addr)
257 printk_stack_address(addr, 0, log_lvl);
258 printk_stack_address(real_addr, reliable, log_lvl);
260 if (!reliable)
261 continue;
263 next:
265 * Get the next frame from the unwinder. No need to
266 * check for an error: if anything goes wrong, the rest
267 * of the addresses will just be printed as unreliable.
269 unwind_next_frame(&state);
271 /* if the frame has entry regs, print them */
272 regs = unwind_get_entry_regs(&state, &partial);
273 if (regs)
274 show_regs_if_on_stack(&stack_info, regs, partial);
277 if (stack_name)
278 printk("%s </%s>\n", log_lvl, stack_name);
282 void show_stack(struct task_struct *task, unsigned long *sp)
284 task = task ? : current;
287 * Stack frames below this one aren't interesting. Don't show them
288 * if we're printing for %current.
290 if (!sp && task == current)
291 sp = get_stack_pointer(current, NULL);
293 show_trace_log_lvl(task, NULL, sp, KERN_DEFAULT);
296 void show_stack_regs(struct pt_regs *regs)
298 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);
301 static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
302 static int die_owner = -1;
303 static unsigned int die_nest_count;
305 unsigned long oops_begin(void)
307 int cpu;
308 unsigned long flags;
310 oops_enter();
312 /* racy, but better than risking deadlock. */
313 raw_local_irq_save(flags);
314 cpu = smp_processor_id();
315 if (!arch_spin_trylock(&die_lock)) {
316 if (cpu == die_owner)
317 /* nested oops. should stop eventually */;
318 else
319 arch_spin_lock(&die_lock);
321 die_nest_count++;
322 die_owner = cpu;
323 console_verbose();
324 bust_spinlocks(1);
325 return flags;
327 NOKPROBE_SYMBOL(oops_begin);
329 void __noreturn rewind_stack_do_exit(int signr);
331 void oops_end(unsigned long flags, struct pt_regs *regs, int signr)
333 if (regs && kexec_should_crash(current))
334 crash_kexec(regs);
336 bust_spinlocks(0);
337 die_owner = -1;
338 add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
339 die_nest_count--;
340 if (!die_nest_count)
341 /* Nest count reaches zero, release the lock. */
342 arch_spin_unlock(&die_lock);
343 raw_local_irq_restore(flags);
344 oops_exit();
346 /* Executive summary in case the oops scrolled away */
347 __show_regs(&exec_summary_regs, SHOW_REGS_ALL);
349 if (!signr)
350 return;
351 if (in_interrupt())
352 panic("Fatal exception in interrupt");
353 if (panic_on_oops)
354 panic("Fatal exception");
357 * We're not going to return, but we might be on an IST stack or
358 * have very little stack space left. Rewind the stack and kill
359 * the task.
360 * Before we rewind the stack, we have to tell KASAN that we're going to
361 * reuse the task stack and that existing poisons are invalid.
363 kasan_unpoison_task_stack(current);
364 rewind_stack_do_exit(signr);
366 NOKPROBE_SYMBOL(oops_end);
368 static void __die_header(const char *str, struct pt_regs *regs, long err)
370 const char *pr = "";
372 /* Save the regs of the first oops for the executive summary later. */
373 if (!die_counter)
374 exec_summary_regs = *regs;
376 if (IS_ENABLED(CONFIG_PREEMPTION))
377 pr = IS_ENABLED(CONFIG_PREEMPT_RT) ? " PREEMPT_RT" : " PREEMPT";
379 printk(KERN_DEFAULT
380 "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
382 IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
383 debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
384 IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
385 IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
386 (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");
388 NOKPROBE_SYMBOL(__die_header);
390 static int __die_body(const char *str, struct pt_regs *regs, long err)
392 show_regs(regs);
393 print_modules();
395 if (notify_die(DIE_OOPS, str, regs, err,
396 current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)
397 return 1;
399 return 0;
401 NOKPROBE_SYMBOL(__die_body);
403 int __die(const char *str, struct pt_regs *regs, long err)
405 __die_header(str, regs, err);
406 return __die_body(str, regs, err);
408 NOKPROBE_SYMBOL(__die);
411 * This is gone through when something in the kernel has done something bad
412 * and is about to be terminated:
414 void die(const char *str, struct pt_regs *regs, long err)
416 unsigned long flags = oops_begin();
417 int sig = SIGSEGV;
419 if (__die(str, regs, err))
420 sig = 0;
421 oops_end(flags, regs, sig);
424 void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr)
426 unsigned long flags = oops_begin();
427 int sig = SIGSEGV;
429 __die_header(str, regs, err);
430 if (gp_addr)
431 kasan_non_canonical_hook(gp_addr);
432 if (__die_body(str, regs, err))
433 sig = 0;
434 oops_end(flags, regs, sig);
437 void show_regs(struct pt_regs *regs)
439 show_regs_print_info(KERN_DEFAULT);
441 __show_regs(regs, user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL);
444 * When in-kernel, we also print out the stack at the time of the fault..
446 if (!user_mode(regs))
447 show_trace_log_lvl(current, regs, NULL, KERN_DEFAULT);