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. */
15 static int crashing_cpu = -1;
16 static cpumask_t cpus_in_crash = CPU_MASK_NONE;
17 
18 #ifdef CONFIG_SMP
crash_shutdown_secondary(void * passed_regs)19 static 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 
crash_kexec_prepare_cpus(void)55 static 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 */
crash_smp_send_stop(void)84 void 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)  */
crash_kexec_prepare_cpus(void)93 static void crash_kexec_prepare_cpus(void) {}
94 #endif /* !defined(CONFIG_SMP)	*/
95 
default_machine_crash_shutdown(struct pt_regs * regs)96 void 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