1 files changed, 44 insertions, 0 deletions

diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index 6ef2899eb861..4b8dbb256147 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -21,6 +21,7 @@
 #include <linux/init.h>
 #include <linux/io.h>
 #include <linux/pci.h>
+#include <linux/kdebug.h>
 
 #include <asm/uv/uv_mmrs.h>
 #include <asm/uv/uv_hub.h>
@@ -41,6 +42,7 @@ static enum uv_system_type uv_system_type;
 static u64 gru_start_paddr, gru_end_paddr;
 int uv_min_hub_revision_id;
 EXPORT_SYMBOL_GPL(uv_min_hub_revision_id);
+static DEFINE_SPINLOCK(uv_nmi_lock);
 
 static inline bool is_GRU_range(u64 start, u64 end)
 {
@@ -74,6 +76,7 @@ static int __init uv_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
         if (!strcmp(oem_id, "SGI")) {
                 nodeid = early_get_nodeid();
                 x86_platform.is_untracked_pat_range =  uv_is_untracked_pat_range;
+                x86_platform.nmi_init = uv_nmi_init;
                 if (!strcmp(oem_table_id, "UVL"))
                         uv_system_type = UV_LEGACY_APIC;
                 else if (!strcmp(oem_table_id, "UVX"))
@@ -596,6 +599,46 @@ void __cpuinit uv_cpu_init(void)
                 set_x2apic_extra_bits(uv_hub_info->pnode);
 }
 
+/*
+ * When NMI is received, print a stack trace.
+ */
+int uv_handle_nmi(struct notifier_block *self, unsigned long reason, void *data)
+{
+        if (reason != DIE_NMI_IPI)
+                return NOTIFY_OK;
+        /*
+         * Use a lock so only one cpu prints at a time
+         * to prevent intermixed output.
+         */
+        spin_lock(&uv_nmi_lock);
+        pr_info("NMI stack dump cpu %u:\n", smp_processor_id());
+        dump_stack();
+        spin_unlock(&uv_nmi_lock);
+
+        return NOTIFY_STOP;
+}
+
+static struct notifier_block uv_dump_stack_nmi_nb = {
+        .notifier_call  = uv_handle_nmi
+};
+
+void uv_register_nmi_notifier(void)
+{
+        if (register_die_notifier(&uv_dump_stack_nmi_nb))
+                printk(KERN_WARNING "UV NMI handler failed to register\n");
+}
+
+void uv_nmi_init(void)
+{
+        unsigned int value;
+
+        /*
+         * Unmask NMI on all cpus
+         */
+        value = apic_read(APIC_LVT1) | APIC_DM_NMI;
+        value &= ~APIC_LVT_MASKED;
+        apic_write(APIC_LVT1, value);
+}
 
 void __init uv_system_init(void)
 {
@@ -717,6 +760,7 @@ void __init uv_system_init(void)
 
         uv_cpu_init();
         uv_scir_register_cpu_notifier();
+        uv_register_nmi_notifier();
         proc_mkdir("sgi_uv", NULL);
 
         /* register Legacy VGA I/O redirection handler */