Merge branch 'for-3.11' of git://linux-nfs.org/~bfields/linux
[linux-2.6.git] / include / linux / uaccess.h
blob5ca0951e1855b103ff65337cef6f94449f34d6c5
1 #ifndef __LINUX_UACCESS_H__
2 #define __LINUX_UACCESS_H__
4 #include <linux/preempt.h>
5 #include <asm/uaccess.h>
7 /*
8 * These routines enable/disable the pagefault handler in that
9 * it will not take any locks and go straight to the fixup table.
11 * They have great resemblance to the preempt_disable/enable calls
12 * and in fact they are identical; this is because currently there is
13 * no other way to make the pagefault handlers do this. So we do
14 * disable preemption but we don't necessarily care about that.
16 static inline void pagefault_disable(void)
18 inc_preempt_count();
20 * make sure to have issued the store before a pagefault
21 * can hit.
23 barrier();
26 static inline void pagefault_enable(void)
29 * make sure to issue those last loads/stores before enabling
30 * the pagefault handler again.
32 barrier();
33 dec_preempt_count();
35 * make sure we do..
37 barrier();
38 preempt_check_resched();
41 #ifndef ARCH_HAS_NOCACHE_UACCESS
43 static inline unsigned long __copy_from_user_inatomic_nocache(void *to,
44 const void __user *from, unsigned long n)
46 return __copy_from_user_inatomic(to, from, n);
49 static inline unsigned long __copy_from_user_nocache(void *to,
50 const void __user *from, unsigned long n)
52 return __copy_from_user(to, from, n);
55 #endif /* ARCH_HAS_NOCACHE_UACCESS */
57 /**
58 * probe_kernel_address(): safely attempt to read from a location
59 * @addr: address to read from - its type is type typeof(retval)*
60 * @retval: read into this variable
62 * Safely read from address @addr into variable @revtal. If a kernel fault
63 * happens, handle that and return -EFAULT.
64 * We ensure that the __get_user() is executed in atomic context so that
65 * do_page_fault() doesn't attempt to take mmap_sem. This makes
66 * probe_kernel_address() suitable for use within regions where the caller
67 * already holds mmap_sem, or other locks which nest inside mmap_sem.
68 * This must be a macro because __get_user() needs to know the types of the
69 * args.
71 * We don't include enough header files to be able to do the set_fs(). We
72 * require that the probe_kernel_address() caller will do that.
74 #define probe_kernel_address(addr, retval) \
75 ({ \
76 long ret; \
77 mm_segment_t old_fs = get_fs(); \
79 set_fs(KERNEL_DS); \
80 pagefault_disable(); \
81 ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval)); \
82 pagefault_enable(); \
83 set_fs(old_fs); \
84 ret; \
88 * probe_kernel_read(): safely attempt to read from a location
89 * @dst: pointer to the buffer that shall take the data
90 * @src: address to read from
91 * @size: size of the data chunk
93 * Safely read from address @src to the buffer at @dst. If a kernel fault
94 * happens, handle that and return -EFAULT.
96 extern long probe_kernel_read(void *dst, const void *src, size_t size);
97 extern long __probe_kernel_read(void *dst, const void *src, size_t size);
100 * probe_kernel_write(): safely attempt to write to a location
101 * @dst: address to write to
102 * @src: pointer to the data that shall be written
103 * @size: size of the data chunk
105 * Safely write to address @dst from the buffer at @src. If a kernel fault
106 * happens, handle that and return -EFAULT.
108 extern long notrace probe_kernel_write(void *dst, const void *src, size_t size);
109 extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size);
111 #endif /* __LINUX_UACCESS_H__ */