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 #include <linux/stop_machine.h> 16 17 static char dump_stack_arch_desc_str[128]; 18 19 /** 20 * dump_stack_set_arch_desc - set arch-specific str to show with task dumps 21 * @fmt: printf-style format string 22 * @...: arguments for the format string 23 * 24 * The configured string will be printed right after utsname during task 25 * dumps. Usually used to add arch-specific system identifiers. If an 26 * arch wants to make use of such an ID string, it should initialize this 27 * as soon as possible during boot. 28 */ 29 void __init dump_stack_set_arch_desc(const char *fmt, ...) 30 { 31 va_list args; 32 33 va_start(args, fmt); 34 vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str), 35 fmt, args); 36 va_end(args); 37 } 38 39 /** 40 * dump_stack_print_info - print generic debug info for dump_stack() 41 * @log_lvl: log level 42 * 43 * Arch-specific dump_stack() implementations can use this function to 44 * print out the same debug information as the generic dump_stack(). 45 */ 46 void dump_stack_print_info(const char *log_lvl) 47 { 48 printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s\n", 49 log_lvl, raw_smp_processor_id(), current->pid, current->comm, 50 kexec_crash_loaded() ? "Kdump: loaded " : "", 51 print_tainted(), 52 init_utsname()->release, 53 (int)strcspn(init_utsname()->version, " "), 54 init_utsname()->version); 55 56 if (dump_stack_arch_desc_str[0] != '\0') 57 printk("%sHardware name: %s\n", 58 log_lvl, dump_stack_arch_desc_str); 59 60 print_worker_info(log_lvl, current); 61 print_stop_info(log_lvl, current); 62 } 63 64 /** 65 * show_regs_print_info - print generic debug info for show_regs() 66 * @log_lvl: log level 67 * 68 * show_regs() implementations can use this function to print out generic 69 * debug information. 70 */ 71 void show_regs_print_info(const char *log_lvl) 72 { 73 dump_stack_print_info(log_lvl); 74 } 75 76 static void __dump_stack(void) 77 { 78 dump_stack_print_info(KERN_DEFAULT); 79 show_stack(NULL, NULL, KERN_DEFAULT); 80 } 81 82 /** 83 * dump_stack - dump the current task information and its stack trace 84 * 85 * Architectures can override this implementation by implementing its own. 86 */ 87 #ifdef CONFIG_SMP 88 static atomic_t dump_lock = ATOMIC_INIT(-1); 89 90 asmlinkage __visible void dump_stack(void) 91 { 92 unsigned long flags; 93 int was_locked; 94 int old; 95 int cpu; 96 97 /* 98 * Permit this cpu to perform nested stack dumps while serialising 99 * against other CPUs 100 */ 101 retry: 102 local_irq_save(flags); 103 cpu = smp_processor_id(); 104 old = atomic_cmpxchg(&dump_lock, -1, cpu); 105 if (old == -1) { 106 was_locked = 0; 107 } else if (old == cpu) { 108 was_locked = 1; 109 } else { 110 local_irq_restore(flags); 111 /* 112 * Wait for the lock to release before jumping to 113 * atomic_cmpxchg() in order to mitigate the thundering herd 114 * problem. 115 */ 116 do { cpu_relax(); } while (atomic_read(&dump_lock) != -1); 117 goto retry; 118 } 119 120 __dump_stack(); 121 122 if (!was_locked) 123 atomic_set(&dump_lock, -1); 124 125 local_irq_restore(flags); 126 } 127 #else 128 asmlinkage __visible void dump_stack(void) 129 { 130 __dump_stack(); 131 } 132 #endif 133 EXPORT_SYMBOL(dump_stack); 134