2 * Memory preserving reboot related code.
4 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
5 * Copyright (C) IBM Corporation, 2004. All rights reserved
8 #include <linux/slab.h>
9 #include <linux/errno.h>
10 #include <linux/highmem.h>
11 #include <linux/crash_dump.h>
13 #include <asm/uaccess.h>
15 static void *kdump_buf_page
;
17 static inline bool is_crashed_pfn_valid(unsigned long pfn
)
19 #ifndef CONFIG_X86_PAE
21 * non-PAE kdump kernel executed from a PAE one will crop high pte
22 * bits and poke unwanted space counting again from address 0, we
23 * don't want that. pte must fit into unsigned long. In fact the
24 * test checks high 12 bits for being zero (pfn will be shifted left
27 return pte_pfn(pfn_pte(pfn
, __pgprot(0))) == pfn
;
34 * copy_oldmem_page - copy one page from "oldmem"
35 * @pfn: page frame number to be copied
36 * @buf: target memory address for the copy; this can be in kernel address
37 * space or user address space (see @userbuf)
38 * @csize: number of bytes to copy
39 * @offset: offset in bytes into the page (based on pfn) to begin the copy
40 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
41 * otherwise @buf is in kernel address space, use memcpy().
43 * Copy a page from "oldmem". For this page, there is no pte mapped
44 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
46 * Calling copy_to_user() in atomic context is not desirable. Hence first
47 * copying the data to a pre-allocated kernel page and then copying to user
48 * space in non-atomic context.
50 ssize_t
copy_oldmem_page(unsigned long pfn
, char *buf
,
51 size_t csize
, unsigned long offset
, int userbuf
)
58 if (!is_crashed_pfn_valid(pfn
))
61 vaddr
= kmap_atomic_pfn(pfn
);
64 memcpy(buf
, (vaddr
+ offset
), csize
);
67 if (!kdump_buf_page
) {
68 printk(KERN_WARNING
"Kdump: Kdump buffer page not"
73 copy_page(kdump_buf_page
, vaddr
);
75 if (copy_to_user(buf
, (kdump_buf_page
+ offset
), csize
))
82 static int __init
kdump_buf_page_init(void)
86 kdump_buf_page
= kmalloc(PAGE_SIZE
, GFP_KERNEL
);
87 if (!kdump_buf_page
) {
88 printk(KERN_WARNING
"Kdump: Failed to allocate kdump buffer"
95 arch_initcall(kdump_buf_page_init
);