text: // SPDX-License-Identifier: GPL-2.0
  /*
   *  HW NMI watchdog support
   *
   *  started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
   *
   *  Arch specific calls to support NMI watchdog
   *
   *  Bits copied from original nmi.c file
   *
   */
  #include <asm/apic.h>
  #include <asm/nmi.h>
  
  #include <linux/cpumask.h>
  #include <linux/kdebug.h>
  #include <linux/notifier.h>
  #include <linux/kprobes.h>
  #include <linux/nmi.h>
  #include <linux/init.h>
  #include <linux/delay.h>
  
  #ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF
  u64 hw_nmi_get_sample_period(int watchdog_thresh)
  {
  	return (u64)(cpu_khz) * 1000 * watchdog_thresh;
  }
  #endif
  
  #ifdef arch_trigger_cpumask_backtrace
  static void nmi_raise_cpu_backtrace(cpumask_t *mask)
  {
  	apic->send_IPI_mask(mask, NMI_VECTOR);
  }
  
  void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self)
  {
  	nmi_trigger_cpumask_backtrace(mask, exclude_self,
  				      nmi_raise_cpu_backtrace);
  }
  
  static int nmi_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs)
  {
  	if (nmi_cpu_backtrace(regs))
  		return NMI_HANDLED;
  
  	return NMI_DONE;
  }
  NOKPROBE_SYMBOL(nmi_cpu_backtrace_handler);
  
  static int __init register_nmi_cpu_backtrace_handler(void)
  {
  	register_nmi_handler(NMI_LOCAL, nmi_cpu_backtrace_handler,
  				0, "arch_bt");
  	return 0;
  }
  early_initcall(register_nmi_cpu_backtrace_handler);
  #endif
  