1/*
 2 * Provide a default dump_stack() function for architectures
 3 * which don't implement their own.
 4 */
 5
 6#include <linux/kernel.h>
 7#include <linux/export.h>
 8#include <linux/sched.h>
 
 9#include <linux/smp.h>
10#include <linux/atomic.h>
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
11
12static void __dump_stack(void)
13{
14	dump_stack_print_info(KERN_DEFAULT);
15	show_stack(NULL, NULL);
16}
17
18/**
19 * dump_stack - dump the current task information and its stack trace
20 *
21 * Architectures can override this implementation by implementing its own.
22 */
23#ifdef CONFIG_SMP
24static atomic_t dump_lock = ATOMIC_INIT(-1);
25
26asmlinkage __visible void dump_stack(void)
27{
 
28	int was_locked;
29	int old;
30	int cpu;
31
32	/*
33	 * Permit this cpu to perform nested stack dumps while serialising
34	 * against other CPUs
35	 */
36	preempt_disable();
37
38retry:
 
39	cpu = smp_processor_id();
40	old = atomic_cmpxchg(&dump_lock, -1, cpu);
41	if (old == -1) {
42		was_locked = 0;
43	} else if (old == cpu) {
44		was_locked = 1;
45	} else {
46		cpu_relax();
 
 
 
 
 
 
47		goto retry;
48	}
49
50	__dump_stack();
51
52	if (!was_locked)
53		atomic_set(&dump_lock, -1);
54
55	preempt_enable();
56}
57#else
58asmlinkage __visible void dump_stack(void)
59{
60	__dump_stack();
61}
62#endif
63EXPORT_SYMBOL(dump_stack);

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Provide a default dump_stack() function for architectures
  4 * which don't implement their own.
  5 */
  6
  7#include <linux/kernel.h>
  8#include <linux/export.h>
  9#include <linux/sched.h>
 10#include <linux/sched/debug.h>
 11#include <linux/smp.h>
 12#include <linux/atomic.h>
 13#include <linux/kexec.h>
 14#include <linux/utsname.h>
 15
 16static char dump_stack_arch_desc_str[128];
 17
 18/**
 19 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
 20 * @fmt: printf-style format string
 21 * @...: arguments for the format string
 22 *
 23 * The configured string will be printed right after utsname during task
 24 * dumps.  Usually used to add arch-specific system identifiers.  If an
 25 * arch wants to make use of such an ID string, it should initialize this
 26 * as soon as possible during boot.
 27 */
 28void __init dump_stack_set_arch_desc(const char *fmt, ...)
 29{
 30	va_list args;
 31
 32	va_start(args, fmt);
 33	vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
 34		  fmt, args);
 35	va_end(args);
 36}
 37
 38/**
 39 * dump_stack_print_info - print generic debug info for dump_stack()
 40 * @log_lvl: log level
 41 *
 42 * Arch-specific dump_stack() implementations can use this function to
 43 * print out the same debug information as the generic dump_stack().
 44 */
 45void dump_stack_print_info(const char *log_lvl)
 46{
 47	printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s\n",
 48	       log_lvl, raw_smp_processor_id(), current->pid, current->comm,
 49	       kexec_crash_loaded() ? "Kdump: loaded " : "",
 50	       print_tainted(),
 51	       init_utsname()->release,
 52	       (int)strcspn(init_utsname()->version, " "),
 53	       init_utsname()->version);
 54
 55	if (dump_stack_arch_desc_str[0] != '\0')
 56		printk("%sHardware name: %s\n",
 57		       log_lvl, dump_stack_arch_desc_str);
 58
 59	print_worker_info(log_lvl, current);
 60}
 61
 62/**
 63 * show_regs_print_info - print generic debug info for show_regs()
 64 * @log_lvl: log level
 65 *
 66 * show_regs() implementations can use this function to print out generic
 67 * debug information.
 68 */
 69void show_regs_print_info(const char *log_lvl)
 70{
 71	dump_stack_print_info(log_lvl);
 72}
 73
 74static void __dump_stack(void)
 75{
 76	dump_stack_print_info(KERN_DEFAULT);
 77	show_stack(NULL, NULL);
 78}
 79
 80/**
 81 * dump_stack - dump the current task information and its stack trace
 82 *
 83 * Architectures can override this implementation by implementing its own.
 84 */
 85#ifdef CONFIG_SMP
 86static atomic_t dump_lock = ATOMIC_INIT(-1);
 87
 88asmlinkage __visible void dump_stack(void)
 89{
 90	unsigned long flags;
 91	int was_locked;
 92	int old;
 93	int cpu;
 94
 95	/*
 96	 * Permit this cpu to perform nested stack dumps while serialising
 97	 * against other CPUs
 98	 */
 
 
 99retry:
100	local_irq_save(flags);
101	cpu = smp_processor_id();
102	old = atomic_cmpxchg(&dump_lock, -1, cpu);
103	if (old == -1) {
104		was_locked = 0;
105	} else if (old == cpu) {
106		was_locked = 1;
107	} else {
108		local_irq_restore(flags);
109		/*
110		 * Wait for the lock to release before jumping to
111		 * atomic_cmpxchg() in order to mitigate the thundering herd
112		 * problem.
113		 */
114		do { cpu_relax(); } while (atomic_read(&dump_lock) != -1);
115		goto retry;
116	}
117
118	__dump_stack();
119
120	if (!was_locked)
121		atomic_set(&dump_lock, -1);
122
123	local_irq_restore(flags);
124}
125#else
126asmlinkage __visible void dump_stack(void)
127{
128	__dump_stack();
129}
130#endif
131EXPORT_SYMBOL(dump_stack);