Commit | Line | Data |
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7aa1c8f4 RB |
1 | #include <linux/highmem.h> |
2 | #include <linux/bootmem.h> | |
3 | #include <linux/crash_dump.h> | |
4 | #include <asm/uaccess.h> | |
e84ff425 | 5 | #include <linux/slab.h> |
7aa1c8f4 | 6 | |
7aa1c8f4 RB |
7 | static void *kdump_buf_page; |
8 | ||
9 | /** | |
10 | * copy_oldmem_page - copy one page from "oldmem" | |
11 | * @pfn: page frame number to be copied | |
12 | * @buf: target memory address for the copy; this can be in kernel address | |
13 | * space or user address space (see @userbuf) | |
14 | * @csize: number of bytes to copy | |
15 | * @offset: offset in bytes into the page (based on pfn) to begin the copy | |
16 | * @userbuf: if set, @buf is in user address space, use copy_to_user(), | |
17 | * otherwise @buf is in kernel address space, use memcpy(). | |
18 | * | |
19 | * Copy a page from "oldmem". For this page, there is no pte mapped | |
20 | * in the current kernel. | |
21 | * | |
22 | * Calling copy_to_user() in atomic context is not desirable. Hence first | |
23 | * copying the data to a pre-allocated kernel page and then copying to user | |
24 | * space in non-atomic context. | |
25 | */ | |
26 | ssize_t copy_oldmem_page(unsigned long pfn, char *buf, | |
27 | size_t csize, unsigned long offset, int userbuf) | |
28 | { | |
29 | void *vaddr; | |
30 | ||
31 | if (!csize) | |
32 | return 0; | |
33 | ||
34 | vaddr = kmap_atomic_pfn(pfn); | |
35 | ||
36 | if (!userbuf) { | |
37 | memcpy(buf, (vaddr + offset), csize); | |
38 | kunmap_atomic(vaddr); | |
39 | } else { | |
40 | if (!kdump_buf_page) { | |
7178d2cd | 41 | pr_warn("Kdump: Kdump buffer page not allocated\n"); |
7aa1c8f4 RB |
42 | |
43 | return -EFAULT; | |
44 | } | |
45 | copy_page(kdump_buf_page, vaddr); | |
46 | kunmap_atomic(vaddr); | |
47 | if (copy_to_user(buf, (kdump_buf_page + offset), csize)) | |
48 | return -EFAULT; | |
49 | } | |
50 | ||
51 | return csize; | |
52 | } | |
53 | ||
54 | static int __init kdump_buf_page_init(void) | |
55 | { | |
56 | int ret = 0; | |
57 | ||
58 | kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
59 | if (!kdump_buf_page) { | |
7178d2cd | 60 | pr_warn("Kdump: Failed to allocate kdump buffer page\n"); |
7aa1c8f4 RB |
61 | ret = -ENOMEM; |
62 | } | |
63 | ||
64 | return ret; | |
65 | } | |
66 | arch_initcall(kdump_buf_page_init); |