blob: c8c9298666fb65cefdf1b5991b7dafa3ad8238dc [file] [log] [blame]
* kernel/crash_dump.c - Memory preserving reboot related code.
* Created by: Simon Horman <>
* Original code moved from kernel/crash.c
* Original code comment copied from the i386 version of this file
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/crash_dump.h>
#include <asm/page.h>
#include <asm/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.
* 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.
copy_oldmem_page(unsigned long pfn, char *buf,
size_t csize, unsigned long offset, int userbuf)
void *vaddr;
if (!csize)
return 0;
vaddr = __va(pfn<<PAGE_SHIFT);
if (userbuf) {
if (copy_to_user(buf, (vaddr + offset), csize)) {
return -EFAULT;
} else
memcpy(buf, (vaddr + offset), csize);
return csize;