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1 | /* |
2 | * Routines for doing kexec-based kdump | |
3 | * | |
4 | * Copyright (C) 2017 Linaro Limited | |
5 | * Author: AKASHI Takahiro <takahiro.akashi@linaro.org> | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License version 2 as | |
9 | * published by the Free Software Foundation. | |
10 | */ | |
11 | ||
12 | #include <linux/crash_dump.h> | |
13 | #include <linux/errno.h> | |
14 | #include <linux/io.h> | |
15 | #include <linux/memblock.h> | |
16 | #include <linux/uaccess.h> | |
17 | #include <asm/memory.h> | |
18 | ||
19 | /** | |
20 | * copy_oldmem_page() - copy one page from old kernel memory | |
21 | * @pfn: page frame number to be copied | |
22 | * @buf: buffer where the copied page is placed | |
23 | * @csize: number of bytes to copy | |
24 | * @offset: offset in bytes into the page | |
25 | * @userbuf: if set, @buf is in a user address space | |
26 | * | |
27 | * This function copies one page from old kernel memory into buffer pointed by | |
28 | * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes | |
29 | * copied or negative error in case of failure. | |
30 | */ | |
31 | ssize_t copy_oldmem_page(unsigned long pfn, char *buf, | |
32 | size_t csize, unsigned long offset, | |
33 | int userbuf) | |
34 | { | |
35 | void *vaddr; | |
36 | ||
37 | if (!csize) | |
38 | return 0; | |
39 | ||
40 | vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB); | |
41 | if (!vaddr) | |
42 | return -ENOMEM; | |
43 | ||
44 | if (userbuf) { | |
45 | if (copy_to_user((char __user *)buf, vaddr + offset, csize)) { | |
46 | memunmap(vaddr); | |
47 | return -EFAULT; | |
48 | } | |
49 | } else { | |
50 | memcpy(buf, vaddr + offset, csize); | |
51 | } | |
52 | ||
53 | memunmap(vaddr); | |
54 | ||
55 | return csize; | |
56 | } | |
57 | ||
58 | /** | |
59 | * elfcorehdr_read - read from ELF core header | |
60 | * @buf: buffer where the data is placed | |
61 | * @csize: number of bytes to read | |
62 | * @ppos: address in the memory | |
63 | * | |
64 | * This function reads @count bytes from elf core header which exists | |
65 | * on crash dump kernel's memory. | |
66 | */ | |
67 | ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos) | |
68 | { | |
69 | memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count); | |
70 | return count; | |
71 | } |