1// SPDX-License-Identifier: GPL-2.0
2#include <linux/kernel.h>
3#include <linux/smp.h>
4#include <linux/reboot.h>
5#include <linux/kexec.h>
6#include <linux/memblock.h>
7#include <linux/crash_dump.h>
8#include <linux/delay.h>
9#include <linux/irq.h>
10#include <linux/types.h>
11#include <linux/sched.h>
12#include <linux/sched/task_stack.h>
13
14/* This keeps a track of which one is crashing cpu. */
15static int crashing_cpu = -1;
16static cpumask_t cpus_in_crash = CPU_MASK_NONE;
17
18#ifdef CONFIG_SMP
19static void crash_shutdown_secondary(void *passed_regs)
20{
21	struct pt_regs *regs = passed_regs;
22	int cpu = smp_processor_id();
23
24	/*
25	 * If we are passed registers, use those.  Otherwise get the
26	 * regs from the last interrupt, which should be correct, as
27	 * we are in an interrupt.  But if the regs are not there,
28	 * pull them from the top of the stack.  They are probably
29	 * wrong, but we need something to keep from crashing again.
30	 */
31	if (!regs)
32		regs = get_irq_regs();
33	if (!regs)
34		regs = task_pt_regs(current);
35
36	if (!cpu_online(cpu))
37		return;
38
39	/* We won't be sent IPIs any more. */
40	set_cpu_online(cpu, false);
41
42	local_irq_disable();
43	if (!cpumask_test_cpu(cpu, &cpus_in_crash))
44		crash_save_cpu(regs, cpu);
45	cpumask_set_cpu(cpu, &cpus_in_crash);
46
47	while (!atomic_read(&kexec_ready_to_reboot))
48		cpu_relax();
49
50	kexec_reboot();
51
52	/* NOTREACHED */
53}
54
55static void crash_kexec_prepare_cpus(void)
56{
57	static int cpus_stopped;
58	unsigned int msecs;
59	unsigned int ncpus;
60
61	if (cpus_stopped)
62		return;
63
64	ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
65
66	smp_call_function(crash_shutdown_secondary, NULL, 0);
67	smp_wmb();
68
69	/*
70	 * The crash CPU sends an IPI and wait for other CPUs to
71	 * respond. Delay of at least 10 seconds.
72	 */
73	pr_emerg("Sending IPI to other cpus...\n");
74	msecs = 10000;
75	while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {
76		cpu_relax();
77		mdelay(1);
78	}
79
80	cpus_stopped = 1;
81}
82
83/* Override the weak function in kernel/panic.c */
84void crash_smp_send_stop(void)
85{
86	if (_crash_smp_send_stop)
87		_crash_smp_send_stop();
88
89	crash_kexec_prepare_cpus();
90}
91
92#else /* !defined(CONFIG_SMP)  */
93static void crash_kexec_prepare_cpus(void) {}
94#endif /* !defined(CONFIG_SMP)	*/
95
96void default_machine_crash_shutdown(struct pt_regs *regs)
97{
98	local_irq_disable();
99	crashing_cpu = smp_processor_id();
100	crash_save_cpu(regs, crashing_cpu);
101	crash_kexec_prepare_cpus();
102	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
103}
104