projects / mirror_ubuntu-bionic-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| 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> | |
| 23 | #include <asm/cacheflush.h> | |
| 24 | #include <asm/page_types.h> | |
| 25 | #include <asm/elf.h> | |
| 26 | #include <asm/livepatch.h> | |
| 27 | ||
| 28 | /** | |
| 29 | * klp_write_module_reloc() - write a relocation in a module | |
| 30 | * @mod: module in which the section to be modified is found | |
| 31 | * @type: ELF relocation type (see asm/elf.h) | |
| 32 | * @loc: address that the relocation should be written to | |
| 33 | * @value: relocation value (sym address + addend) | |
| 34 | * | |
| 35 | * This function writes a relocation to the specified location for | |
| 36 | * a particular module. | |
| 37 | */ | |
| 38 | int klp_write_module_reloc(struct module *mod, unsigned long type, | |
| 39 | unsigned long loc, unsigned long value) | |
| 40 | { | |
| 41 | int ret, numpages, size = 4; | |
| 42 | bool readonly; | |
| 43 | unsigned long val; | |
| 44 | unsigned long core = (unsigned long)mod->module_core; | |
| 45 | unsigned long core_ro_size = mod->core_ro_size; | |
| 46 | unsigned long core_size = mod->core_size; | |
| 47 | ||
| 48 | switch (type) { | |
| 49 | case R_X86_64_NONE: | |
| 50 | return 0; | |
| 51 | case R_X86_64_64: | |
| 52 | val = value; | |
| 53 | size = 8; | |
| 54 | break; | |
| 55 | case R_X86_64_32: | |
| 56 | val = (u32)value; | |
| 57 | break; | |
| 58 | case R_X86_64_32S: | |
| 59 | val = (s32)value; | |
| 60 | break; | |
| 61 | case R_X86_64_PC32: | |
| 62 | val = (u32)(value - loc); | |
| 63 | break; | |
| 64 | default: | |
| 65 | /* unsupported relocation type */ | |
| 66 | return -EINVAL; | |
| 67 | } | |
| 68 | ||
| 69 | if (loc < core || loc >= core + core_size) | |
| 70 | /* loc does not point to any symbol inside the module */ | |
| 71 | return -EINVAL; | |
| 72 | ||
| 73 | if (loc < core + core_ro_size) | |
| 74 | readonly = true; | |
| 75 | else | |
| 76 | readonly = false; | |
| 77 | ||
| 78 | /* determine if the relocation spans a page boundary */ | |
| 79 | numpages = ((loc & PAGE_MASK) == ((loc + size) & PAGE_MASK)) ? 1 : 2; | |
| 80 | ||
| 81 | if (readonly) | |
| 82 | set_memory_rw(loc & PAGE_MASK, numpages); | |
| 83 | ||
| 84 | ret = probe_kernel_write((void *)loc, &val, size); | |
| 85 | ||
| 86 | if (readonly) | |
| 87 | set_memory_ro(loc & PAGE_MASK, numpages); | |
| 88 | ||
| 89 | return ret; | |
| 90 | } |