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/buildid.h>
9#include <linux/export.h>
10#include <linux/sched.h>
11#include <linux/sched/debug.h>
12#include <linux/smp.h>
13#include <linux/atomic.h>
14#include <linux/kexec.h>
15#include <linux/utsname.h>
16#include <linux/stop_machine.h>
17
18static char dump_stack_arch_desc_str[128];
19
20/**
21 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
22 * @fmt: printf-style format string
23 * @...: arguments for the format string
24 *
25 * The configured string will be printed right after utsname during task
26 * dumps.  Usually used to add arch-specific system identifiers.  If an
27 * arch wants to make use of such an ID string, it should initialize this
28 * as soon as possible during boot.
29 */
30void __init dump_stack_set_arch_desc(const char *fmt, ...)
31{
32	va_list args;
33
34	va_start(args, fmt);
35	vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
36		  fmt, args);
37	va_end(args);
38}
39
40#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID)
41#define BUILD_ID_FMT " %20phN"
42#define BUILD_ID_VAL vmlinux_build_id
43#else
44#define BUILD_ID_FMT "%s"
45#define BUILD_ID_VAL ""
46#endif
47
48/**
49 * dump_stack_print_info - print generic debug info for dump_stack()
50 * @log_lvl: log level
51 *
52 * Arch-specific dump_stack() implementations can use this function to
53 * print out the same debug information as the generic dump_stack().
54 */
55void dump_stack_print_info(const char *log_lvl)
56{
57	printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s" BUILD_ID_FMT "\n",
58	       log_lvl, raw_smp_processor_id(), current->pid, current->comm,
59	       kexec_crash_loaded() ? "Kdump: loaded " : "",
60	       print_tainted(),
61	       init_utsname()->release,
62	       (int)strcspn(init_utsname()->version, " "),
63	       init_utsname()->version, BUILD_ID_VAL);
64
65	if (dump_stack_arch_desc_str[0] != '\0')
66		printk("%sHardware name: %s\n",
67		       log_lvl, dump_stack_arch_desc_str);
68
69	print_worker_info(log_lvl, current);
70	print_stop_info(log_lvl, current);
71}
72
73/**
74 * show_regs_print_info - print generic debug info for show_regs()
75 * @log_lvl: log level
76 *
77 * show_regs() implementations can use this function to print out generic
78 * debug information.
79 */
80void show_regs_print_info(const char *log_lvl)
81{
82	dump_stack_print_info(log_lvl);
83}
84
85static void __dump_stack(const char *log_lvl)
86{
87	dump_stack_print_info(log_lvl);
88	show_stack(NULL, NULL, log_lvl);
89}
90
91/**
92 * dump_stack_lvl - dump the current task information and its stack trace
93 * @log_lvl: log level
94 *
95 * Architectures can override this implementation by implementing its own.
96 */
97asmlinkage __visible void dump_stack_lvl(const char *log_lvl)
98{
99	bool in_panic = this_cpu_in_panic();
100	unsigned long flags;
101
102	/*
103	 * Permit this cpu to perform nested stack dumps while serialising
104	 * against other CPUs, unless this CPU is in panic.
105	 *
106	 * When in panic, non-panic CPUs are not permitted to store new
107	 * printk messages so there is no need to synchronize the output.
108	 * This avoids potential deadlock in panic() if another CPU is
109	 * holding and unable to release the printk_cpu_sync.
110	 */
111	if (!in_panic)
112		printk_cpu_sync_get_irqsave(flags);
113
114	__dump_stack(log_lvl);
115
116	if (!in_panic)
117		printk_cpu_sync_put_irqrestore(flags);
118}
119EXPORT_SYMBOL(dump_stack_lvl);
120
121asmlinkage __visible void dump_stack(void)
122{
123	dump_stack_lvl(KERN_DEFAULT);
124}
125EXPORT_SYMBOL(dump_stack);
126