linux-kernel - [RFC Patch 9/9] Cleanup HW Breakpoint registers before kexec

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Date:	Thu, 9 Oct 2008 00:57:00 +0530
From:	"K.Prasad" <prasad@...ux.vnet.ibm.com>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Roland McGrath <roland@...hat.com>, akpm@...ux-foundation.org,
	mingo@...e.hu, jason.wessel@...driver.com, avi@...ranet.com,
	richardj_moore@...ibm.com
Subject: [RFC Patch 9/9] Cleanup HW Breakpoint registers before kexec


This patch disables Hardware breakpoints before doing a 'kexec' on the machine.

Signed-off-by: K.Prasad <prasad@...ux.vnet.ibm.com>
Signed-off-by: Alan Stern <stern@...land.harvard.edu>
---
 arch/x86/kernel/machine_kexec_32.c |    2 ++
 arch/x86/kernel/machine_kexec_64.c |    2 ++
 2 files changed, 4 insertions(+)

Index: linux-bkpt-lkml-27-rc9/arch/x86/kernel/machine_kexec_32.c
===================================================================
--- linux-bkpt-lkml-27-rc9.orig/arch/x86/kernel/machine_kexec_32.c
+++ linux-bkpt-lkml-27-rc9/arch/x86/kernel/machine_kexec_32.c
@@ -24,6 +24,7 @@
 #include <asm/desc.h>
 #include <asm/system.h>
 #include <asm/cacheflush.h>
+#include <asm/debugreg.h>
 
 #define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
 static u32 kexec_pgd[1024] PAGE_ALIGNED;
@@ -131,6 +132,7 @@ void machine_kexec(struct kimage *image)
 
 	/* Interrupts aren't acceptable while we reboot */
 	local_irq_disable();
+	disable_debug_registers();
 
 	if (image->preserve_context) {
 #ifdef CONFIG_X86_IO_APIC
Index: linux-bkpt-lkml-27-rc9/arch/x86/kernel/machine_kexec_64.c
===================================================================
--- linux-bkpt-lkml-27-rc9.orig/arch/x86/kernel/machine_kexec_64.c
+++ linux-bkpt-lkml-27-rc9/arch/x86/kernel/machine_kexec_64.c
@@ -17,6 +17,7 @@
 #include <asm/tlbflush.h>
 #include <asm/mmu_context.h>
 #include <asm/io.h>
+#include <asm/debugreg.h>
 
 #define PAGE_ALIGNED __attribute__ ((__aligned__(PAGE_SIZE)))
 static u64 kexec_pgd[512] PAGE_ALIGNED;
@@ -190,6 +191,7 @@ void machine_kexec(struct kimage *image)
 
 	/* Interrupts aren't acceptable while we reboot */
 	local_irq_disable();
+	disable_debug_registers();
 
 	control_page = page_address(image->control_code_page) + PAGE_SIZE;
 	memcpy(control_page, relocate_kernel, PAGE_SIZE);
--
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