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b700e7f0 SJ |
1 | /* |
2 | * livepatch.c - x86-specific Kernel Live Patching Core | |
3 | * | |
4 | * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com> | |
5 | * Copyright (C) 2014 SUSE | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version 2 | |
10 | * of the License, or (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, see <http://www.gnu.org/licenses/>. | |
19 | */ | |
20 | ||
21 | #include <linux/module.h> | |
22 | #include <linux/uaccess.h> | |
b700e7f0 SJ |
23 | #include <asm/elf.h> |
24 | #include <asm/livepatch.h> | |
25 | ||
26 | /** | |
27 | * klp_write_module_reloc() - write a relocation in a module | |
28 | * @mod: module in which the section to be modified is found | |
29 | * @type: ELF relocation type (see asm/elf.h) | |
30 | * @loc: address that the relocation should be written to | |
31 | * @value: relocation value (sym address + addend) | |
32 | * | |
33 | * This function writes a relocation to the specified location for | |
34 | * a particular module. | |
35 | */ | |
36 | int klp_write_module_reloc(struct module *mod, unsigned long type, | |
37 | unsigned long loc, unsigned long value) | |
38 | { | |
b56b36ee | 39 | size_t size = 4; |
b700e7f0 | 40 | unsigned long val; |
7523e4dc RR |
41 | unsigned long core = (unsigned long)mod->core_layout.base; |
42 | unsigned long core_size = mod->core_layout.size; | |
b700e7f0 SJ |
43 | |
44 | switch (type) { | |
45 | case R_X86_64_NONE: | |
46 | return 0; | |
47 | case R_X86_64_64: | |
48 | val = value; | |
49 | size = 8; | |
50 | break; | |
51 | case R_X86_64_32: | |
52 | val = (u32)value; | |
53 | break; | |
54 | case R_X86_64_32S: | |
55 | val = (s32)value; | |
56 | break; | |
57 | case R_X86_64_PC32: | |
58 | val = (u32)(value - loc); | |
59 | break; | |
60 | default: | |
61 | /* unsupported relocation type */ | |
62 | return -EINVAL; | |
63 | } | |
64 | ||
65 | if (loc < core || loc >= core + core_size) | |
66 | /* loc does not point to any symbol inside the module */ | |
67 | return -EINVAL; | |
68 | ||
b56b36ee | 69 | return probe_kernel_write((void *)loc, &val, size); |
b700e7f0 | 70 | } |