/*
* fs/proc/vmcore.c Interface for accessing the crash
* dump from the system's previous life.
* Heavily borrowed from fs/proc/kcore.c
* Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
* Copyright (C) IBM Corporation, 2004. All rights reserved
*
*/
#include <linux/mm.h>
#include <linux/kcore.h>
#include <linux/user.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/printk.h>
#include <linux/bootmem.h>
#include <linux/init.h>
#include <linux/crash_dump.h>
#include <linux/list.h>
#include <linux/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/uaccess.h>
#include <asm/io.h>
#include "internal.h"
/* List representing chunks of contiguous memory areas and their offsets in
* vmcore file.
*/
static LIST_HEAD(vmcore_list);
/* Stores the pointer to the buffer containing kernel elf core headers. */
static char *elfcorebuf;
static size_t elfcorebuf_sz;
static size_t elfcorebuf_sz_orig;
static char *elfnotes_buf;
static size_t elfnotes_sz;
/* Total size of vmcore file. */
static u64 vmcore_size;
static struct proc_dir_entry *proc_vmcore;
/*
* Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
* The called function has to take care of module refcounting.
*/
static int (*oldmem_pfn_is_ram)(unsigned long pfn);
int register_oldmem_pfn_is_ram(int (*fn)(unsigned long pfn))
{
if (oldmem_pfn_is_ram)
return -EBUSY;
oldmem_pfn_is_ram = fn;
return 0;
}
EXPORT_SYMBOL_GPL(register_oldmem_pfn_is_ram);
void unregister_oldmem_pfn_is_ram(void)
{
oldmem_pfn_is_ram = NULL;
wmb();
}
EXPORT_SYMBOL_GPL(unregister_oldmem_pfn_is_ram);
static int pfn_is_ram(unsigned long pfn)
{
int (*fn)(unsigned long pfn);
/* pfn is ram unless fn() checks pagetype */
int ret = 1;
/*
* Ask hypervisor if the pfn is really ram.
* A ballooned page contains no data and reading from such a page
* will cause high load in the hypervisor.
*/
fn = oldmem_pfn_is_ram;
if (fn)
ret = fn(pfn);
return ret;
}
/* Reads a page from the oldmem device from given offset. */
static ssize_t read_from_oldmem(char *buf, size_t count,
u64 *ppos, int userbuf)
{
unsigned long pfn, offset;
size_t nr_bytes;
ssize_t read = 0, tmp;
if (!count)
return 0;
offset = (unsigned long)(*ppos % PAGE_SIZE);
pfn = (unsigned long)(*ppos / PAGE_SIZE);
do {
if (count > (PAGE_SIZE - offset))
nr_bytes = PAGE_SIZE - offset;
else
nr_bytes = count;
/* If pfn is not ram, return zeros for sparse dump files */
if (pfn_is_ram(pfn) == 0)
memset(buf, 0, nr_bytes);
else {
tmp = copy_oldmem_page(pfn, buf, nr_bytes,
offset, userbuf);
if (tmp < 0)
return tmp;
}
*ppos += nr_bytes;
count -= nr_bytes;
buf += nr_bytes;
read += nr_bytes;
++pfn;
offset = 0;
} while (count);
return read;
}
/*