Seth Jennings | b700e7f | 2014-12-16 11:58:19 -0600 | [diff] [blame] | 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> |
Seth Jennings | b700e7f | 2014-12-16 11:58:19 -0600 | [diff] [blame] | 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 | { |
Josh Poimboeuf | b56b36e | 2015-12-03 16:33:26 -0600 | [diff] [blame] | 39 | size_t size = 4; |
Seth Jennings | b700e7f | 2014-12-16 11:58:19 -0600 | [diff] [blame] | 40 | unsigned long val; |
Rusty Russell | 7523e4d | 2015-11-26 09:44:08 +1030 | [diff] [blame] | 41 | unsigned long core = (unsigned long)mod->core_layout.base; |
| 42 | unsigned long core_size = mod->core_layout.size; |
Seth Jennings | b700e7f | 2014-12-16 11:58:19 -0600 | [diff] [blame] | 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 | |
Josh Poimboeuf | b56b36e | 2015-12-03 16:33:26 -0600 | [diff] [blame] | 69 | return probe_kernel_write((void *)loc, &val, size); |
Seth Jennings | b700e7f | 2014-12-16 11:58:19 -0600 | [diff] [blame] | 70 | } |