Commit 4ae362be authored by Vivek Goyal's avatar Vivek Goyal Committed by Linus Torvalds
Browse files

[PATCH] kdump: read previous kernel's memory 



- Moving the crash_dump.c file to arch dependent part as kmap_atomic_pfn is
  specific to i386 and highmem may not exist in other archs.

- Use ioremap for x86_64 to map the previous kernel memory.

- In copy_oldmem_page(), we now directly copy to the user/kernel buffer and
  avoid the unneccesary copy to a kmalloc'd page.

Signed-off-by: default avatarRachita Kothiyal <rachita@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 ec9ce0db

arch/i386/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -25,6 +25,7 @@ obj-$(CONFIG_X86_LOCAL_APIC) += apic.o nmi.o 
obj-$(CONFIG_X86_IO_APIC)	+= io_apic.o

obj-$(CONFIG_X86_REBOOTFIXUPS)	+= reboot_fixups.o

obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o crash.o

obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o

obj-$(CONFIG_X86_NUMAQ)		+= numaq.o

obj-$(CONFIG_X86_SUMMIT_NUMA)	+= summit.o

obj-$(CONFIG_KPROBES)		+= kprobes.o

arch/i386/kernel/crash_dump.c

0 → 100644
+74 −0
Original line number Diff line number Diff line 
/*

 *	kernel/crash_dump.c - Memory preserving reboot related code.

 *

 *	Created by: Hariprasad Nellitheertha (hari@in.ibm.com)

 *	Copyright (C) IBM Corporation, 2004. All rights reserved

 */



#include <linux/errno.h>

#include <linux/highmem.h>

#include <linux/crash_dump.h>



#include <asm/uaccess.h>



static void *kdump_buf_page;



/**

 * copy_oldmem_page - copy one page from "oldmem"

 * @pfn: page frame number to be copied

 * @buf: target memory address for the copy; this can be in kernel address

 *	space or user address space (see @userbuf)

 * @csize: number of bytes to copy

 * @offset: offset in bytes into the page (based on pfn) to begin the copy

 * @userbuf: if set, @buf is in user address space, use copy_to_user(),

 *	otherwise @buf is in kernel address space, use memcpy().

 *

 * Copy a page from "oldmem". For this page, there is no pte mapped

 * in the current kernel. We stitch up a pte, similar to kmap_atomic.

 *

 * Calling copy_to_user() in atomic context is not desirable. Hence first

 * copying the data to a pre-allocated kernel page and then copying to user

 * space in non-atomic context.

 */

ssize_t copy_oldmem_page(unsigned long pfn, char *buf,

                               size_t csize, unsigned long offset, int userbuf)

{

	void  *vaddr;



	if (!csize)

		return 0;



	vaddr = kmap_atomic_pfn(pfn, KM_PTE0);



	if (!userbuf) {

		memcpy(buf, (vaddr + offset), csize);

		kunmap_atomic(vaddr, KM_PTE0);

	} else {

		if (!kdump_buf_page) {

			printk(KERN_WARNING "Kdump: Kdump buffer page not"

				" allocated\n");

			return -EFAULT;

		}

		copy_page(kdump_buf_page, vaddr);

		kunmap_atomic(vaddr, KM_PTE0);

		if (copy_to_user(buf, (kdump_buf_page + offset), csize))

			return -EFAULT;

	}



	return csize;

}



static int __init kdump_buf_page_init(void)

{

	int ret = 0;



	kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL);

	if (!kdump_buf_page) {

		printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer"

			 " page\n");

		ret = -ENOMEM;

	}



	return ret;

}

arch_initcall(kdump_buf_page_init);

arch/x86_64/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ obj-$(CONFIG_X86_LOCAL_APIC) += apic.o nmi.o 
obj-$(CONFIG_X86_IO_APIC)	+= io_apic.o mpparse.o \

		genapic.o genapic_cluster.o genapic_flat.o

obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o crash.o

obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o

obj-$(CONFIG_PM)		+= suspend.o

obj-$(CONFIG_SOFTWARE_SUSPEND)	+= suspend_asm.o

obj-$(CONFIG_CPU_FREQ)		+= cpufreq/

kernel/crash_dump.c→arch/x86_64/kernel/crash_dump.c

+9 −26
Original line number Diff line number Diff line
@@ -5,21 +5,12 @@ 
 *	Copyright (C) IBM Corporation, 2004. All rights reserved

 */



#include <linux/smp_lock.h>

#include <linux/errno.h>

#include <linux/proc_fs.h>

#include <linux/bootmem.h>

#include <linux/highmem.h>

#include <linux/crash_dump.h>



#include <asm/io.h>

#include <asm/uaccess.h>

#include <asm/kexec.h>



/* Stores the physical address of elf header of crash image. */

unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;

#include <asm/io.h>



#ifndef HAVE_ARCH_COPY_OLDMEM_PAGE

/**

 * copy_oldmem_page - copy one page from "oldmem"

 * @pfn: page frame number to be copied
@@ -36,29 +27,21 @@ unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; 
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,

                               size_t csize, unsigned long offset, int userbuf)

{

	void *page, *vaddr;

	void  *vaddr;



	if (!csize)

		return 0;



	page = kmalloc(PAGE_SIZE, GFP_KERNEL);

	if (!page)

		return -ENOMEM;



	vaddr = kmap_atomic_pfn(pfn, KM_PTE0);

	copy_page(page, vaddr);

	kunmap_atomic(vaddr, KM_PTE0);

	vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);



	if (userbuf) {

		if (copy_to_user(buf, (page + offset), csize)) {

			kfree(page);

		if (copy_to_user(buf, (vaddr + offset), csize)) {

			iounmap(vaddr);

			return -EFAULT;

		}

	} else {

		memcpy(buf, (page + offset), csize);

	}

	} else

	memcpy(buf, (vaddr + offset), csize);



	kfree(page);

	iounmap(vaddr);

	return csize;

}
 
#endif

fs/proc/vmcore.c

+3 −0
Original line number Diff line number Diff line
@@ -35,6 +35,9 @@ static size_t elfcorebuf_sz; 
/* Total size of vmcore file. */

static u64 vmcore_size;



/* Stores the physical address of elf header of crash image. */

unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;



struct proc_dir_entry *proc_vmcore = NULL;



/* Reads a page from the oldmem device from given offset. */