blob: 4e348dbaecd75a297e59101aa9cb5b9ffc872968 [file] [log] [blame]
Ingo Molnarc33fa9f2008-04-17 20:05:36 +02001/*
2 * Access kernel memory without faulting.
3 */
4#include <linux/uaccess.h>
5#include <linux/module.h>
6#include <linux/mm.h>
7
8/**
9 * probe_kernel_read(): safely attempt to read from a location
10 * @dst: pointer to the buffer that shall take the data
11 * @src: address to read from
12 * @size: size of the data chunk
13 *
14 * Safely read from address @src to the buffer at @dst. If a kernel fault
15 * happens, handle that and return -EFAULT.
16 */
Jason Wessel6144a852010-01-07 11:58:36 -060017
18long __weak probe_kernel_read(void *dst, void *src, size_t size)
19 __attribute__((alias("__probe_kernel_read")));
20
21long __probe_kernel_read(void *dst, void *src, size_t size)
Ingo Molnarc33fa9f2008-04-17 20:05:36 +020022{
23 long ret;
Jason Wesselb4b8ac52008-02-20 13:33:38 -060024 mm_segment_t old_fs = get_fs();
Ingo Molnarc33fa9f2008-04-17 20:05:36 +020025
Jason Wesselb4b8ac52008-02-20 13:33:38 -060026 set_fs(KERNEL_DS);
Ingo Molnarc33fa9f2008-04-17 20:05:36 +020027 pagefault_disable();
28 ret = __copy_from_user_inatomic(dst,
29 (__force const void __user *)src, size);
30 pagefault_enable();
Jason Wesselb4b8ac52008-02-20 13:33:38 -060031 set_fs(old_fs);
Ingo Molnarc33fa9f2008-04-17 20:05:36 +020032
33 return ret ? -EFAULT : 0;
34}
35EXPORT_SYMBOL_GPL(probe_kernel_read);
36
37/**
38 * probe_kernel_write(): safely attempt to write to a location
39 * @dst: address to write to
40 * @src: pointer to the data that shall be written
41 * @size: size of the data chunk
42 *
43 * Safely write to address @dst from the buffer at @src. If a kernel fault
44 * happens, handle that and return -EFAULT.
45 */
Jason Wessel6144a852010-01-07 11:58:36 -060046long __weak probe_kernel_write(void *dst, void *src, size_t size)
47 __attribute__((alias("__probe_kernel_write")));
48
49long __probe_kernel_write(void *dst, void *src, size_t size)
Ingo Molnarc33fa9f2008-04-17 20:05:36 +020050{
51 long ret;
Jason Wesselb4b8ac52008-02-20 13:33:38 -060052 mm_segment_t old_fs = get_fs();
Ingo Molnarc33fa9f2008-04-17 20:05:36 +020053
Jason Wesselb4b8ac52008-02-20 13:33:38 -060054 set_fs(KERNEL_DS);
Ingo Molnarc33fa9f2008-04-17 20:05:36 +020055 pagefault_disable();
56 ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
57 pagefault_enable();
Jason Wesselb4b8ac52008-02-20 13:33:38 -060058 set_fs(old_fs);
Ingo Molnarc33fa9f2008-04-17 20:05:36 +020059
60 return ret ? -EFAULT : 0;
61}
62EXPORT_SYMBOL_GPL(probe_kernel_write);