[PATCH] crashdump: x86: add NMI handler to capture other CPUs

#include <asm/hardirq.h>

#include <asm/nmi.h>

#include <asm/hw_irq.h>

#include <mach_ipi.h>

#define MAX_NOTE_BYTES 1024

typedef u32 note_buf_t[MAX_NOTE_BYTES/4];

note_buf_t crash_notes[NR_CPUS];

#ifdef CONFIG_SMP

static atomic_t waiting_for_crash_ipi;

static int crash_nmi_callback(struct pt_regs *regs, int cpu)

{

	local_irq_disable();

	atomic_dec(&waiting_for_crash_ipi);

	/* Assume hlt works */

	__asm__("hlt");

	for(;;);

	return 1;

}

/*

 * By using the NMI code instead of a vector we just sneak thru the

 * word generator coming out with just what we want.  AND it does

 * not matter if clustered_apic_mode is set or not.

 */

static void smp_send_nmi_allbutself(void)

{

	send_IPI_allbutself(APIC_DM_NMI);

}

static void nmi_shootdown_cpus(void)

{

	unsigned long msecs;

	atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);

	/* Would it be better to replace the trap vector here? */

	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 */

}

#else

static void nmi_shootdown_cpus(void)

{

	/* There are no cpus to shootdown */

}

#endif

void machine_crash_shutdown(void)

{

	/* This function is only called after the system

	 * In practice this means shooting down the other cpus in

	 * an SMP system.

	 */

	/* The kernel is broken so disable interrupts */

	local_irq_disable();

	nmi_shootdown_cpus();

}