arch/mips/kernel/crash.c

   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/bootmem.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         local_irq_disable();
  40         if (!cpumask_test_cpu(cpu, &cpus_in_crash))
  41                 crash_save_cpu(regs, cpu);
  42         cpumask_set_cpu(cpu, &cpus_in_crash);
  43
  44         while (!atomic_read(&kexec_ready_to_reboot))
  45                 cpu_relax();
  46         relocated_kexec_smp_wait(NULL);
  47         /* NOTREACHED */
  48 }
  49
  50 static void crash_kexec_prepare_cpus(void)
  51 {
  52         static int cpus_stopped;
  53         unsigned int msecs;
  54         unsigned int ncpus;
  55
  56         if (cpus_stopped)
  57                 return;
  58
  59         ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
  60
  61         smp_call_function(crash_shutdown_secondary, NULL, 0);
  62         smp_wmb();
  63
  64         /*
  65          * The crash CPU sends an IPI and wait for other CPUs to
  66          * respond. Delay of at least 10 seconds.
  67          */
  68         pr_emerg("Sending IPI to other cpus...\n");
  69         msecs = 10000;
  70         while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {
  71                 cpu_relax();
  72                 mdelay(1);
  73         }
  74
  75         cpus_stopped = 1;
  76 }
  77
  78 /* Override the weak function in kernel/panic.c */
  79 void crash_smp_send_stop(void)
  80 {
  81         if (_crash_smp_send_stop)
  82                 _crash_smp_send_stop();
  83
  84         crash_kexec_prepare_cpus();
  85 }
  86
  87 #else /* !defined(CONFIG_SMP)  */
  88 static void crash_kexec_prepare_cpus(void) {}
  89 #endif /* !defined(CONFIG_SMP)  */
  90
  91 void default_machine_crash_shutdown(struct pt_regs *regs)
  92 {
  93         local_irq_disable();
  94         crashing_cpu = smp_processor_id();
  95         crash_save_cpu(regs, crashing_cpu);
  96         crash_kexec_prepare_cpus();
  97         cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
  98 }