68 lines
1.7 KiB
C
68 lines
1.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/highmem.h>
|
|
#include <linux/bootmem.h>
|
|
#include <linux/crash_dump.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/slab.h>
|
|
|
|
static void *kdump_buf_page;
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* 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 = kmap_atomic_pfn(pfn);
|
|
|
|
if (!userbuf) {
|
|
memcpy(buf, (vaddr + offset), csize);
|
|
kunmap_atomic(vaddr);
|
|
} else {
|
|
if (!kdump_buf_page) {
|
|
pr_warn("Kdump: Kdump buffer page not allocated\n");
|
|
|
|
return -EFAULT;
|
|
}
|
|
copy_page(kdump_buf_page, vaddr);
|
|
kunmap_atomic(vaddr);
|
|
if (copy_to_user(buf, (kdump_buf_page + offset), csize))
|
|
return -EFAULT;
|
|
}
|
|
|
|
return csize;
|
|
}
|
|
|
|
static int __init kdump_buf_page_init(void)
|
|
{
|
|
int ret = 0;
|
|
|
|
kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL);
|
|
if (!kdump_buf_page) {
|
|
pr_warn("Kdump: Failed to allocate kdump buffer page\n");
|
|
ret = -ENOMEM;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
arch_initcall(kdump_buf_page_init);
|