mirror of https://gitee.com/openkylin/linux.git
47 lines
1.3 KiB
C
47 lines
1.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* 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/crash_dump.h>
|
|
#include <linux/io.h>
|
|
#include <linux/uaccess.h>
|
|
|
|
/**
|
|
* 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.
|
|
*/
|
|
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 = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
|
|
|
|
if (userbuf) {
|
|
if (copy_to_user(buf, (vaddr + offset), csize)) {
|
|
iounmap(vaddr);
|
|
return -EFAULT;
|
|
}
|
|
} else
|
|
memcpy(buf, (vaddr + offset), csize);
|
|
|
|
iounmap(vaddr);
|
|
return csize;
|
|
}
|