Commit cffe632a authored by akpm@osdl.org's avatar akpm@osdl.org Committed by Linus Torvalds
Browse files

[PATCH] kdump: x86_64 kexec on panic 




)

From: Vivek Goyal <vgoyal@in.ibm.com>

- Implementing the machine_crash_shutdown for x86_64 which will be called by
  crash_kexec (called in case of a panic, sysrq etc.).  Here we do things
  similar to i386.  Disable the interrupts, shootdown the cpus and shutdown
  LAPIC and IOAPIC.

Changes in this version:

- As the Eric's APIC initialization patches are reverted back, reintroducing
  LAPIC and IOAPIC shutdown.

- Added some comments on CPU hotplug, modified code as suggested by Andi
  kleen.

Signed-off-by: default avatarMurali M Chakravarthy <muralim@in.ibm.com>
Signed-off-by: default avatarVivek Goyal <vgoyal@in.ibm.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent aac04b32

arch/x86_64/kernel/crash.c

+85 −1
Original line number Diff line number Diff line
@@ -13,15 +13,85 @@ 
#include <linux/smp.h>

#include <linux/reboot.h>

#include <linux/kexec.h>

#include <linux/delay.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 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();



	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.
@@ -29,4 +99,18 @@ 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



}

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