mirror of
https://github.com/torvalds/linux.git
synced 2024-11-19 18:41:48 +00:00
49 lines
1.4 KiB
C
49 lines
1.4 KiB
C
|
/*
|
||
|
|
* kernel/crash_dump.c - Memory preserving reboot related code.
|
||
|
|
*
|
||
|
|
* Created by: Simon Horman <horms@verge.net.au>
|
||
|
|
* 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/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.
|
||
|
|
*/
|
||
|
|
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 = __va(pfn<<PAGE_SHIFT);
|
||
|
|
if (userbuf) {
|
||
|
|
if (copy_to_user(buf, (vaddr + offset), csize)) {
|
||
|
|
return -EFAULT;
|
||
|
|
}
|
||
|
|
} else
|
||
|
|
memcpy(buf, (vaddr + offset), csize);
|
||
|
|
return csize;
|
||
|
|
}
|
||
|
|
|