// 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
  ",
  	       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
  ",
  		       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_SMP
  static 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);

  }
  #else

  asmlinkage __visible void dump_stack(void)

  {
  	__dump_stack();

  }

  #endif

  EXPORT_SYMBOL(dump_stack);