[PATCH] kdump: Routines for copying dump pages

This patch provides the interfaces necessary to read the dump contents,
treating it as a high memory device.

Signed off by Hariprasad Nellitheertha <hari@in.ibm.com>
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Vivek Goyal 2005-06-25 14:58:19 -07:00 committed by Linus Torvalds
parent 5f016456c9
commit 60e64d46a5
6 changed files with 83 additions and 0 deletions

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@ -75,6 +75,24 @@ void kunmap_atomic(void *kvaddr, enum km_type type)
preempt_check_resched();
}
/* This is the same as kmap_atomic() but can map memory that doesn't
* have a struct page associated with it.
*/
void *kmap_atomic_pfn(unsigned long pfn, enum km_type type)
{
enum fixed_addresses idx;
unsigned long vaddr;
inc_preempt_count();
idx = type + KM_TYPE_NR*smp_processor_id();
vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
set_pte(kmap_pte-idx, pfn_pte(pfn, kmap_prot));
__flush_tlb_one(vaddr);
return (void*) vaddr;
}
struct page *kmap_atomic_to_page(void *ptr)
{
unsigned long idx, vaddr = (unsigned long)ptr;

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@ -70,6 +70,7 @@ void *kmap(struct page *page);
void kunmap(struct page *page);
void *kmap_atomic(struct page *page, enum km_type type);
void kunmap_atomic(void *kvaddr, enum km_type type);
void *kmap_atomic_pfn(unsigned long pfn, enum km_type type);
struct page *kmap_atomic_to_page(void *ptr);
#define flush_cache_kmaps() do { } while (0)

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@ -0,0 +1,13 @@
#ifndef LINUX_CRASH_DUMP_H
#define LINUX_CRASH_DUMP_H
#ifdef CONFIG_CRASH_DUMP
#include <linux/kexec.h>
#include <linux/smp_lock.h>
#include <linux/device.h>
#include <linux/proc_fs.h>
extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
unsigned long, int);
#endif /* CONFIG_CRASH_DUMP */
#endif /* LINUX_CRASHDUMP_H */

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@ -28,6 +28,7 @@ static inline void *kmap(struct page *page)
#define kmap_atomic(page, idx) page_address(page)
#define kunmap_atomic(addr, idx) do { } while (0)
#define kmap_atomic_pfn(pfn, idx) page_address(pfn_to_page(pfn))
#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
#endif /* CONFIG_HIGHMEM */

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@ -28,6 +28,7 @@ obj-$(CONFIG_AUDITSYSCALL) += auditsc.o
obj-$(CONFIG_KPROBES) += kprobes.o
obj-$(CONFIG_SYSFS) += ksysfs.o
obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_SECCOMP) += seccomp.o
ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)

49
kernel/crash_dump.c Normal file
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@ -0,0 +1,49 @@
/*
* 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/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>
/*
* 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.
*/
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset, int userbuf)
{
void *page, *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);
if (userbuf) {
if (copy_to_user(buf, (page + offset), csize)) {
kfree(page);
return -EFAULT;
}
} else {
memcpy(buf, (page + offset), csize);
}
kfree(page);
return csize;
}