1 files changed, 154 insertions, 2 deletions

diff --git a/arch/x86_64/kernel/crash.c b/arch/x86_64/kernel/crash.c
index 535e04466079..4e6c3b729e39 100644
--- a/arch/x86_64/kernel/crash.c
+++ b/arch/x86_64/kernel/crash.c
@@ -11,19 +11,156 @@
 #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 <asm/processor.h>
 #include <asm/hardirq.h>
 #include <asm/nmi.h>
 #include <asm/hw_irq.h>
+#include <asm/mach_apic.h>
 
-note_buf_t crash_notes[NR_CPUS];
+/* This keeps a track of which one is crashing cpu. */
+static int crashing_cpu;
+
+static u32 *append_elf_note(u32 *buf, char *name, unsigned type,
+                                                void *data, size_t data_len)
+{
+        struct elf_note note;
+
+        note.n_namesz = strlen(name) + 1;
+        note.n_descsz = data_len;
+        note.n_type   = type;
+        memcpy(buf, &note, sizeof(note));
+        buf += (sizeof(note) +3)/4;
+        memcpy(buf, name, note.n_namesz);
+        buf += (note.n_namesz + 3)/4;
+        memcpy(buf, data, note.n_descsz);
+        buf += (note.n_descsz + 3)/4;
+
+        return buf;
+}
+
+static void final_note(u32 *buf)
+{
+        struct elf_note note;
+
+        note.n_namesz = 0;
+        note.n_descsz = 0;
+        note.n_type   = 0;
+        memcpy(buf, &note, sizeof(note));
+}
+
+static void crash_save_this_cpu(struct pt_regs *regs, int cpu)
+{
+        struct elf_prstatus prstatus;
+        u32 *buf;
+
+        if ((cpu < 0) || (cpu >= NR_CPUS))
+                return;
+
+        /* Using ELF notes here is opportunistic.
+         * I need a well defined structure format
+         * for the data I pass, and I need tags
+         * on the data to indicate what information I have
+         * squirrelled away.  ELF notes happen to provide
+         * all of that that no need to invent something new.
+         */
+
+        buf = (u32*)per_cpu_ptr(crash_notes, cpu);
+
+        if (!buf)
+                return;
+
+        memset(&prstatus, 0, sizeof(prstatus));
+        prstatus.pr_pid = current->pid;
+        elf_core_copy_regs(&prstatus.pr_reg, regs);
+        buf = append_elf_note(buf, "CORE", NT_PRSTATUS, &prstatus,
+                                        sizeof(prstatus));
+        final_note(buf);
+}
+
+static void crash_save_self(struct pt_regs *regs)
+{
+        int cpu;
+
+        cpu = smp_processor_id();
+        crash_save_this_cpu(regs, cpu);
+}
+
+#ifdef CONFIG_SMP
+static atomic_t waiting_for_crash_ipi;
+
+static int crash_nmi_callback(struct pt_regs *regs, int cpu)
+{
+        /*
+         * 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 1;
+        local_irq_disable();
+
+        crash_save_this_cpu(regs, cpu);
+        disable_local_APIC();
+        atomic_dec(&waiting_for_crash_ipi);
+        /* Assume hlt works */
+        for(;;)
+                asm("hlt");
+
+        return 1;
+}
+
+static void smp_send_nmi_allbutself(void)
+{
+        send_IPI_allbutself(APIC_DM_NMI);
+}
+
+/*
+ * This code is a best effort heuristic to get the
+ * other cpus to stop executing. So races with
+ * cpu hotplug shouldn't matter.
+ */
+
+static void nmi_shootdown_cpus(void)
+{
+        unsigned long msecs;
+
+        atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
+        set_nmi_callback(crash_nmi_callback);
+
+        /*
+         * 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
+        /*
+         * This function is only called after the system
          * has paniced 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.
@@ -31,4 +168,19 @@ void machine_crash_shutdown(struct pt_regs *regs)
          * 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();
+
+#if defined(CONFIG_X86_IO_APIC)
+        disable_IO_APIC();
+#endif
+
+        crash_save_self(regs);
 }