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 14 static void __dump_stack(void) 15 { 16 dump_stack_print_info(KERN_DEFAULT); 17 show_stack(NULL, NULL); 18 } 19 20 /** 21 * dump_stack - dump the current task information and its stack trace 22 * 23 * Architectures can override this implementation by implementing its own. 24 */ 25 #ifdef CONFIG_SMP 26 static atomic_t dump_lock = ATOMIC_INIT(-1); 27 28 asmlinkage __visible void dump_stack(void) 29 { 30 unsigned long flags; 31 int was_locked; 32 int old; 33 int cpu; 34 35 /* 36 * Permit this cpu to perform nested stack dumps while serialising 37 * against other CPUs 38 */ 39 retry: 40 local_irq_save(flags); 41 cpu = smp_processor_id(); 42 old = atomic_cmpxchg(&dump_lock, -1, cpu); 43 if (old == -1) { 44 was_locked = 0; 45 } else if (old == cpu) { 46 was_locked = 1; 47 } else { 48 local_irq_restore(flags); 49 cpu_relax(); 50 goto retry; 51 } 52 53 __dump_stack(); 54 55 if (!was_locked) 56 atomic_set(&dump_lock, -1); 57 58 local_irq_restore(flags); 59 } 60 #else 61 asmlinkage __visible void dump_stack(void) 62 { 63 __dump_stack(); 64 } 65 #endif 66 EXPORT_SYMBOL(dump_stack); 67