USB: fix thread-unsafe anchor utiliy routines
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / mm / maccess.c
blob4e348dbaecd75a297e59101aa9cb5b9ffc872968
1 /*
2 * Access kernel memory without faulting.
3 */
4 #include <linux/uaccess.h>
5 #include <linux/module.h>
6 #include <linux/mm.h>
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
14 * Safely read from address @src to the buffer at @dst. If a kernel fault
15 * happens, handle that and return -EFAULT.
18 long __weak probe_kernel_read(void *dst, void *src, size_t size)
19 __attribute__((alias("__probe_kernel_read")));
21 long __probe_kernel_read(void *dst, void *src, size_t size)
23 long ret;
24 mm_segment_t old_fs = get_fs();
26 set_fs(KERNEL_DS);
27 pagefault_disable();
28 ret = __copy_from_user_inatomic(dst,
29 (__force const void __user *)src, size);
30 pagefault_enable();
31 set_fs(old_fs);
33 return ret ? -EFAULT : 0;
35 EXPORT_SYMBOL_GPL(probe_kernel_read);
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
43 * Safely write to address @dst from the buffer at @src. If a kernel fault
44 * happens, handle that and return -EFAULT.
46 long __weak probe_kernel_write(void *dst, void *src, size_t size)
47 __attribute__((alias("__probe_kernel_write")));
49 long __probe_kernel_write(void *dst, void *src, size_t size)
51 long ret;
52 mm_segment_t old_fs = get_fs();
54 set_fs(KERNEL_DS);
55 pagefault_disable();
56 ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
57 pagefault_enable();
58 set_fs(old_fs);
60 return ret ? -EFAULT : 0;
62 EXPORT_SYMBOL_GPL(probe_kernel_write);