1 files changed, 92 insertions, 0 deletions

diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c
index 0e3dbc7b2bdb..ba7b9a0e6063 100644
--- a/arch/x86/kernel/reboot.c
+++ b/arch/x86/kernel/reboot.c
@@ -21,6 +21,9 @@
 # include <asm/iommu.h>
 #endif
 
+#include <mach_ipi.h>
+
+
 /*
  * Power off function, if any
  */
@@ -548,3 +551,92 @@ void machine_crash_shutdown(struct pt_regs *regs)
         machine_ops.crash_shutdown(regs);
 }
 #endif
+
+
+#if defined(CONFIG_SMP)
+
+/* This keeps a track of which one is crashing cpu. */
+static int crashing_cpu;
+static nmi_shootdown_cb shootdown_callback;
+
+static atomic_t waiting_for_crash_ipi;
+
+static int crash_nmi_callback(struct notifier_block *self,
+                        unsigned long val, void *data)
+{
+        int cpu;
+
+        if (val != DIE_NMI_IPI)
+                return NOTIFY_OK;
+
+        cpu = raw_smp_processor_id();
+
+        /* Don't do anything if this handler is invoked on crashing cpu.
+         * Otherwise, system will completely hang. Crashing cpu can get
+         * an NMI if system was initially booted with nmi_watchdog parameter.
+         */
+        if (cpu == crashing_cpu)
+                return NOTIFY_STOP;
+        local_irq_disable();
+
+        shootdown_callback(cpu, (struct die_args *)data);
+
+        atomic_dec(&waiting_for_crash_ipi);
+        /* Assume hlt works */
+        halt();
+        for (;;)
+                cpu_relax();
+
+        return 1;
+}
+
+static void smp_send_nmi_allbutself(void)
+{
+        send_IPI_allbutself(NMI_VECTOR);
+}
+
+static struct notifier_block crash_nmi_nb = {
+        .notifier_call = crash_nmi_callback,
+};
+
+/* Halt all other CPUs, calling the specified function on each of them
+ *
+ * This function can be used to halt all other CPUs on crash
+ * or emergency reboot time. The function passed as parameter
+ * will be called inside a NMI handler on all CPUs.
+ */
+void nmi_shootdown_cpus(nmi_shootdown_cb callback)
+{
+        unsigned long msecs;
+        local_irq_disable();
+
+        /* Make a note of crashing cpu. Will be used in NMI callback.*/
+        crashing_cpu = safe_smp_processor_id();
+
+        shootdown_callback = callback;
+
+        atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
+        /* Would it be better to replace the trap vector here? */
+        if (register_die_notifier(&crash_nmi_nb))
+                return;         /* return what? */
+        /* Ensure the new callback function is set before sending
+         * out the NMI
+         */
+        wmb();
+
+        smp_send_nmi_allbutself();
+
+        msecs = 1000; /* Wait at most a second for the other cpus to stop */
+        while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
+                mdelay(1);
+                msecs--;
+        }
+
+        /* Leave the nmi callback set */
+}
+#else /* !CONFIG_SMP */
+void nmi_shootdown_cpus(nmi_shootdown_cb callback)
+{
+        /* No other CPUs to shoot down */
+}
+#endif