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
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
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 */
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) */
93 static void crash_kexec_prepare_cpus(void) {}
94 #endif /* !defined(CONFIG_SMP) */
95
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
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