1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Provide a default dump_stack() function for architectures
4*4882a593Smuzhiyun * which don't implement their own.
5*4882a593Smuzhiyun */
6*4882a593Smuzhiyun
7*4882a593Smuzhiyun #include <linux/kernel.h>
8*4882a593Smuzhiyun #include <linux/export.h>
9*4882a593Smuzhiyun #include <linux/sched.h>
10*4882a593Smuzhiyun #include <linux/sched/debug.h>
11*4882a593Smuzhiyun #include <linux/smp.h>
12*4882a593Smuzhiyun #include <linux/atomic.h>
13*4882a593Smuzhiyun #include <linux/kexec.h>
14*4882a593Smuzhiyun #include <linux/utsname.h>
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun static char dump_stack_arch_desc_str[128];
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun /**
19*4882a593Smuzhiyun * dump_stack_set_arch_desc - set arch-specific str to show with task dumps
20*4882a593Smuzhiyun * @fmt: printf-style format string
21*4882a593Smuzhiyun * @...: arguments for the format string
22*4882a593Smuzhiyun *
23*4882a593Smuzhiyun * The configured string will be printed right after utsname during task
24*4882a593Smuzhiyun * dumps. Usually used to add arch-specific system identifiers. If an
25*4882a593Smuzhiyun * arch wants to make use of such an ID string, it should initialize this
26*4882a593Smuzhiyun * as soon as possible during boot.
27*4882a593Smuzhiyun */
dump_stack_set_arch_desc(const char * fmt,...)28*4882a593Smuzhiyun void __init dump_stack_set_arch_desc(const char *fmt, ...)
29*4882a593Smuzhiyun {
30*4882a593Smuzhiyun va_list args;
31*4882a593Smuzhiyun
32*4882a593Smuzhiyun va_start(args, fmt);
33*4882a593Smuzhiyun vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),
34*4882a593Smuzhiyun fmt, args);
35*4882a593Smuzhiyun va_end(args);
36*4882a593Smuzhiyun }
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun /**
39*4882a593Smuzhiyun * dump_stack_print_info - print generic debug info for dump_stack()
40*4882a593Smuzhiyun * @log_lvl: log level
41*4882a593Smuzhiyun *
42*4882a593Smuzhiyun * Arch-specific dump_stack() implementations can use this function to
43*4882a593Smuzhiyun * print out the same debug information as the generic dump_stack().
44*4882a593Smuzhiyun */
dump_stack_print_info(const char * log_lvl)45*4882a593Smuzhiyun void dump_stack_print_info(const char *log_lvl)
46*4882a593Smuzhiyun {
47*4882a593Smuzhiyun printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s\n",
48*4882a593Smuzhiyun log_lvl, raw_smp_processor_id(), current->pid, current->comm,
49*4882a593Smuzhiyun kexec_crash_loaded() ? "Kdump: loaded " : "",
50*4882a593Smuzhiyun print_tainted(),
51*4882a593Smuzhiyun init_utsname()->release,
52*4882a593Smuzhiyun (int)strcspn(init_utsname()->version, " "),
53*4882a593Smuzhiyun init_utsname()->version);
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun if (dump_stack_arch_desc_str[0] != '\0')
56*4882a593Smuzhiyun printk("%sHardware name: %s\n",
57*4882a593Smuzhiyun log_lvl, dump_stack_arch_desc_str);
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun print_worker_info(log_lvl, current);
60*4882a593Smuzhiyun }
61*4882a593Smuzhiyun
62*4882a593Smuzhiyun /**
63*4882a593Smuzhiyun * show_regs_print_info - print generic debug info for show_regs()
64*4882a593Smuzhiyun * @log_lvl: log level
65*4882a593Smuzhiyun *
66*4882a593Smuzhiyun * show_regs() implementations can use this function to print out generic
67*4882a593Smuzhiyun * debug information.
68*4882a593Smuzhiyun */
show_regs_print_info(const char * log_lvl)69*4882a593Smuzhiyun void show_regs_print_info(const char *log_lvl)
70*4882a593Smuzhiyun {
71*4882a593Smuzhiyun dump_stack_print_info(log_lvl);
72*4882a593Smuzhiyun }
73*4882a593Smuzhiyun
__dump_stack(const char * log_lvl)74*4882a593Smuzhiyun static void __dump_stack(const char *log_lvl)
75*4882a593Smuzhiyun {
76*4882a593Smuzhiyun dump_stack_print_info(log_lvl);
77*4882a593Smuzhiyun show_stack(NULL, NULL, log_lvl);
78*4882a593Smuzhiyun }
79*4882a593Smuzhiyun
80*4882a593Smuzhiyun /**
81*4882a593Smuzhiyun * dump_stack - dump the current task information and its stack trace
82*4882a593Smuzhiyun *
83*4882a593Smuzhiyun * Architectures can override this implementation by implementing its own.
84*4882a593Smuzhiyun */
85*4882a593Smuzhiyun #ifdef CONFIG_SMP
86*4882a593Smuzhiyun static atomic_t dump_lock = ATOMIC_INIT(-1);
87*4882a593Smuzhiyun
dump_stack_lvl(const char * log_lvl)88*4882a593Smuzhiyun asmlinkage __visible void dump_stack_lvl(const char *log_lvl)
89*4882a593Smuzhiyun {
90*4882a593Smuzhiyun unsigned long flags;
91*4882a593Smuzhiyun int was_locked;
92*4882a593Smuzhiyun int old;
93*4882a593Smuzhiyun int cpu;
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun /*
96*4882a593Smuzhiyun * Permit this cpu to perform nested stack dumps while serialising
97*4882a593Smuzhiyun * against other CPUs
98*4882a593Smuzhiyun */
99*4882a593Smuzhiyun retry:
100*4882a593Smuzhiyun local_irq_save(flags);
101*4882a593Smuzhiyun cpu = smp_processor_id();
102*4882a593Smuzhiyun old = atomic_cmpxchg(&dump_lock, -1, cpu);
103*4882a593Smuzhiyun if (old == -1) {
104*4882a593Smuzhiyun was_locked = 0;
105*4882a593Smuzhiyun } else if (old == cpu) {
106*4882a593Smuzhiyun was_locked = 1;
107*4882a593Smuzhiyun } else {
108*4882a593Smuzhiyun local_irq_restore(flags);
109*4882a593Smuzhiyun /*
110*4882a593Smuzhiyun * Wait for the lock to release before jumping to
111*4882a593Smuzhiyun * atomic_cmpxchg() in order to mitigate the thundering herd
112*4882a593Smuzhiyun * problem.
113*4882a593Smuzhiyun */
114*4882a593Smuzhiyun do { cpu_relax(); } while (atomic_read(&dump_lock) != -1);
115*4882a593Smuzhiyun goto retry;
116*4882a593Smuzhiyun }
117*4882a593Smuzhiyun
118*4882a593Smuzhiyun __dump_stack(log_lvl);
119*4882a593Smuzhiyun
120*4882a593Smuzhiyun if (!was_locked)
121*4882a593Smuzhiyun atomic_set(&dump_lock, -1);
122*4882a593Smuzhiyun
123*4882a593Smuzhiyun local_irq_restore(flags);
124*4882a593Smuzhiyun }
125*4882a593Smuzhiyun #else
dump_stack_lvl(const char * log_lvl)126*4882a593Smuzhiyun asmlinkage __visible void dump_stack_lvl(const char *log_lvl)
127*4882a593Smuzhiyun {
128*4882a593Smuzhiyun __dump_stack(log_lvl);
129*4882a593Smuzhiyun }
130*4882a593Smuzhiyun #endif
131*4882a593Smuzhiyun EXPORT_SYMBOL(dump_stack_lvl);
132*4882a593Smuzhiyun
dump_stack(void)133*4882a593Smuzhiyun asmlinkage __visible void dump_stack(void)
134*4882a593Smuzhiyun {
135*4882a593Smuzhiyun dump_stack_lvl(KERN_DEFAULT);
136*4882a593Smuzhiyun }
137*4882a593Smuzhiyun EXPORT_SYMBOL(dump_stack);
138