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git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - arch/x86/kernel/livepatch.c
2 * livepatch.c - x86-specific Kernel Live Patching Core
4 * Copyright (C) 2014 Seth Jennings <sjenning@redhat.com>
5 * Copyright (C) 2014 SUSE
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.
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.
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/>.
21 #include <linux/module.h>
22 #include <linux/uaccess.h>
23 #include <asm/cacheflush.h>
24 #include <asm/page_types.h>
26 #include <asm/livepatch.h>
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)
35 * This function writes a relocation to the specified location for
36 * a particular module.
38 int klp_write_module_reloc(struct module
*mod
, unsigned long type
,
39 unsigned long loc
, unsigned long value
)
41 int ret
, numpages
, size
= 4;
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
;
62 val
= (u32
)(value
- loc
);
65 /* unsupported relocation type */
69 if (loc
< core
|| loc
>= core
+ core_size
)
70 /* loc does not point to any symbol inside the module */
73 if (loc
< core
+ core_ro_size
)
78 /* determine if the relocation spans a page boundary */
79 numpages
= ((loc
& PAGE_MASK
) == ((loc
+ size
) & PAGE_MASK
)) ? 1 : 2;
82 set_memory_rw(loc
& PAGE_MASK
, numpages
);
84 ret
= probe_kernel_write((void *)loc
, &val
, size
);
87 set_memory_ro(loc
& PAGE_MASK
, numpages
);