// SPDX-License-Identifier: GPL-2.0/* * Provide a default dump_stack() function for architectures * which don't implement their own. */ #include <linux/kernel.h>#include <linux/export.h>#include <linux/sched.h>#include <linux/sched/debug.h>#include <linux/smp.h>#include <linux/atomic.h>#include <linux/kexec.h>#include <linux/utsname.h> static char dump_stack_arch_desc_str[128]; /** * dump_stack_set_arch_desc - set arch-specific str to show with task dumps * @fmt: printf-style format string * @...: arguments for the format string * * The configured string will be printed right after utsname during task * dumps.  Usually used to add arch-specific system identifiers.  If an * arch wants to make use of such an ID string, it should initialize this * as soon as possible during boot. */void __init dump_stack_set_arch_desc(const char *fmt, ...){	va_list args; 	va_start(args, fmt);	vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str),		  fmt, args);	va_end(args);} /** * dump_stack_print_info - print generic debug info for dump_stack() * @log_lvl: log level * * Arch-specific dump_stack() implementations can use this function to * print out the same debug information as the generic dump_stack(). */void dump_stack_print_info(const char *log_lvl){	printk("%sCPU: %d PID: %d Comm: %.20s %s%s %s %.*s\n",	       log_lvl, raw_smp_processor_id(), current->pid, current->comm,	       kexec_crash_loaded() ? "Kdump: loaded " : "",	       print_tainted(),	       init_utsname()->release,	       (int)strcspn(init_utsname()->version, " "),	       init_utsname()->version); 	if (dump_stack_arch_desc_str[0] != '\0')		printk("%sHardware name: %s\n",		       log_lvl, dump_stack_arch_desc_str); 	print_worker_info(log_lvl, current);} /** * show_regs_print_info - print generic debug info for show_regs() * @log_lvl: log level * * show_regs() implementations can use this function to print out generic * debug information. */void show_regs_print_info(const char *log_lvl){	dump_stack_print_info(log_lvl);} static void __dump_stack(void){	dump_stack_print_info(KERN_DEFAULT);	show_stack(NULL, NULL);} /** * dump_stack - dump the current task information and its stack trace * * Architectures can override this implementation by implementing its own. */#ifdef CONFIG_SMPstatic atomic_t dump_lock = ATOMIC_INIT(-1); asmlinkage __visible void dump_stack(void){	unsigned long flags;	int was_locked;	int old;	int cpu; 	/*	 * Permit this cpu to perform nested stack dumps while serialising	 * against other CPUs	 */retry:	local_irq_save(flags);	cpu = smp_processor_id();	old = atomic_cmpxchg(&dump_lock, -1, cpu);	if (old == -1) {		was_locked = 0;	} else if (old == cpu) {		was_locked = 1;	} else {		local_irq_restore(flags);		cpu_relax();		goto retry;	} 	__dump_stack(); 	if (!was_locked)		atomic_set(&dump_lock, -1); 	local_irq_restore(flags);}#elseasmlinkage __visible void dump_stack(void){	__dump_stack();}#endifEXPORT_SYMBOL(dump_stack);