1 files changed, 135 insertions, 0 deletions

diff --git a/arch/x86/kernel/crash_64.c b/arch/x86/kernel/crash_64.c
new file mode 100644
index 000000000000..13432a1ae904
--- /dev/null
+++ b/arch/x86/kernel/crash_64.c
@@ -0,0 +1,135 @@
+/*
+ * Architecture specific (x86_64) functions for kexec based crash dumps.
+ *
+ * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
+ *
+ * Copyright (C) IBM Corporation, 2004. All rights reserved.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/smp.h>
+#include <linux/irq.h>
+#include <linux/reboot.h>
+#include <linux/kexec.h>
+#include <linux/delay.h>
+#include <linux/elf.h>
+#include <linux/elfcore.h>
+#include <linux/kdebug.h>
+
+#include <asm/processor.h>
+#include <asm/hardirq.h>
+#include <asm/nmi.h>
+#include <asm/hw_irq.h>
+#include <asm/mach_apic.h>
+
+/* This keeps a track of which one is crashing cpu. */
+static int crashing_cpu;
+
+#ifdef CONFIG_SMP
+static atomic_t waiting_for_crash_ipi;
+
+static int crash_nmi_callback(struct notifier_block *self,
+                                unsigned long val, void *data)
+{
+        struct pt_regs *regs;
+        int cpu;
+
+        if (val != DIE_NMI_IPI)
+                return NOTIFY_OK;
+
+        regs = ((struct die_args *)data)->regs;
+        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();
+
+        crash_save_cpu(regs, cpu);
+        disable_local_APIC();
+        atomic_dec(&waiting_for_crash_ipi);
+        /* Assume hlt works */
+        for(;;)
+                halt();
+
+        return 1;
+}
+
+static void smp_send_nmi_allbutself(void)
+{
+        send_IPI_allbutself(NMI_VECTOR);
+}
+
+/*
+ * This code is a best effort heuristic to get the
+ * other cpus to stop executing. So races with
+ * cpu hotplug shouldn't matter.
+ */
+
+static struct notifier_block crash_nmi_nb = {
+        .notifier_call = crash_nmi_callback,
+};
+
+static void nmi_shootdown_cpus(void)
+{
+        unsigned long msecs;
+
+        atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
+        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 */
+        disable_local_APIC();
+}
+#else
+static void nmi_shootdown_cpus(void)
+{
+        /* There are no cpus to shootdown */
+}
+#endif
+
+void machine_crash_shutdown(struct pt_regs *regs)
+{
+        /*
+         * This function is only called after the system
+         * has panicked or is otherwise in a critical state.
+         * The minimum amount of code to allow a kexec'd kernel
+         * to run successfully needs to happen here.
+         *
+         * In practice this means shooting down the other cpus in
+         * an SMP system.
+         */
+        /* The kernel is broken so disable interrupts */
+        local_irq_disable();
+
+        /* Make a note of crashing cpu. Will be used in NMI callback.*/
+        crashing_cpu = smp_processor_id();
+        nmi_shootdown_cpus();
+
+        if(cpu_has_apic)
+                 disable_local_APIC();
+
+        disable_IO_APIC();
+
+        crash_save_cpu(regs, smp_processor_id());
+}