Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
7aa1c8f4 | 2 | #include <linux/highmem.h> |
57c8a661 | 3 | #include <linux/memblock.h> |
7aa1c8f4 | 4 | #include <linux/crash_dump.h> |
7c0f6ba6 | 5 | #include <linux/uaccess.h> |
e84ff425 | 6 | #include <linux/slab.h> |
7aa1c8f4 | 7 | |
7aa1c8f4 RB |
8 | static void *kdump_buf_page; |
9 | ||
10 | /** | |
11 | * copy_oldmem_page - copy one page from "oldmem" | |
12 | * @pfn: page frame number to be copied | |
13 | * @buf: target memory address for the copy; this can be in kernel address | |
14 | * space or user address space (see @userbuf) | |
15 | * @csize: number of bytes to copy | |
16 | * @offset: offset in bytes into the page (based on pfn) to begin the copy | |
17 | * @userbuf: if set, @buf is in user address space, use copy_to_user(), | |
18 | * otherwise @buf is in kernel address space, use memcpy(). | |
19 | * | |
20 | * Copy a page from "oldmem". For this page, there is no pte mapped | |
21 | * in the current kernel. | |
22 | * | |
23 | * Calling copy_to_user() in atomic context is not desirable. Hence first | |
24 | * copying the data to a pre-allocated kernel page and then copying to user | |
25 | * space in non-atomic context. | |
26 | */ | |
27 | ssize_t copy_oldmem_page(unsigned long pfn, char *buf, | |
28 | size_t csize, unsigned long offset, int userbuf) | |
29 | { | |
30 | void *vaddr; | |
31 | ||
32 | if (!csize) | |
33 | return 0; | |
34 | ||
35 | vaddr = kmap_atomic_pfn(pfn); | |
36 | ||
37 | if (!userbuf) { | |
38 | memcpy(buf, (vaddr + offset), csize); | |
39 | kunmap_atomic(vaddr); | |
40 | } else { | |
41 | if (!kdump_buf_page) { | |
7178d2cd | 42 | pr_warn("Kdump: Kdump buffer page not allocated\n"); |
7aa1c8f4 RB |
43 | |
44 | return -EFAULT; | |
45 | } | |
46 | copy_page(kdump_buf_page, vaddr); | |
47 | kunmap_atomic(vaddr); | |
48 | if (copy_to_user(buf, (kdump_buf_page + offset), csize)) | |
49 | return -EFAULT; | |
50 | } | |
51 | ||
52 | return csize; | |
53 | } | |
54 | ||
55 | static int __init kdump_buf_page_init(void) | |
56 | { | |
57 | int ret = 0; | |
58 | ||
59 | kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
60 | if (!kdump_buf_page) { | |
7178d2cd | 61 | pr_warn("Kdump: Failed to allocate kdump buffer page\n"); |
7aa1c8f4 RB |
62 | ret = -ENOMEM; |
63 | } | |
64 | ||
65 | return ret; | |
66 | } | |
67 | arch_initcall(kdump_buf_page_init); |