// SPDX-License-Identifier: GPL-2.0#include <linux/kernel.h>#include <linux/smp.h>#include <linux/reboot.h>#include <linux/kexec.h>#include <linux/memblock.h>#include <linux/crash_dump.h>#include <linux/delay.h>#include <linux/irq.h>#include <linux/types.h>#include <linux/sched.h>#include <linux/sched/task_stack.h> /* This keeps a track of which one is crashing cpu. */static int crashing_cpu = -1;static cpumask_t cpus_in_crash = CPU_MASK_NONE; #ifdef CONFIG_SMPstatic void crash_shutdown_secondary(void *passed_regs){	struct pt_regs *regs = passed_regs;	int cpu = smp_processor_id(); 	/*	 * If we are passed registers, use those.  Otherwise get the	 * regs from the last interrupt, which should be correct, as	 * we are in an interrupt.  But if the regs are not there,	 * pull them from the top of the stack.  They are probably	 * wrong, but we need something to keep from crashing again.	 */	if (!regs)		regs = get_irq_regs();	if (!regs)		regs = task_pt_regs(current); 	if (!cpu_online(cpu))		return; 	/* We won't be sent IPIs any more. */	set_cpu_online(cpu, false); 	local_irq_disable();	if (!cpumask_test_cpu(cpu, &cpus_in_crash))		crash_save_cpu(regs, cpu);	cpumask_set_cpu(cpu, &cpus_in_crash); 	while (!atomic_read(&kexec_ready_to_reboot))		cpu_relax(); 	kexec_reboot(); 	/* NOTREACHED */} static void crash_kexec_prepare_cpus(void){	static int cpus_stopped;	unsigned int msecs;	unsigned int ncpus; 	if (cpus_stopped)		return; 	ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */ 	smp_call_function(crash_shutdown_secondary, NULL, 0);	smp_wmb(); 	/*	 * The crash CPU sends an IPI and wait for other CPUs to	 * respond. Delay of at least 10 seconds.	 */	pr_emerg("Sending IPI to other cpus...\n");	msecs = 10000;	while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {		cpu_relax();		mdelay(1);	} 	cpus_stopped = 1;} /* Override the weak function in kernel/panic.c */void crash_smp_send_stop(void){	if (_crash_smp_send_stop)		_crash_smp_send_stop(); 	crash_kexec_prepare_cpus();} #else /* !defined(CONFIG_SMP)  */static void crash_kexec_prepare_cpus(void) {}#endif /* !defined(CONFIG_SMP)	*/ void default_machine_crash_shutdown(struct pt_regs *regs){	local_irq_disable();	crashing_cpu = smp_processor_id();	crash_save_cpu(regs, crashing_cpu);	crash_kexec_prepare_cpus();	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);}