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c22ce143 HY |
1 | #ifndef __LINUX_UACCESS_H__ |
2 | #define __LINUX_UACCESS_H__ | |
3 | ||
a866374a | 4 | #include <linux/preempt.h> |
c22ce143 HY |
5 | #include <asm/uaccess.h> |
6 | ||
a866374a PZ |
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. | |
10 | * | |
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. | |
15 | */ | |
16 | static inline void pagefault_disable(void) | |
17 | { | |
bdb43806 | 18 | preempt_count_inc(); |
a866374a PZ |
19 | /* |
20 | * make sure to have issued the store before a pagefault | |
21 | * can hit. | |
22 | */ | |
23 | barrier(); | |
24 | } | |
25 | ||
26 | static inline void pagefault_enable(void) | |
27 | { | |
62b94a08 | 28 | #ifndef CONFIG_PREEMPT |
a866374a PZ |
29 | /* |
30 | * make sure to issue those last loads/stores before enabling | |
31 | * the pagefault handler again. | |
32 | */ | |
33 | barrier(); | |
bdb43806 | 34 | preempt_count_dec(); |
62b94a08 PZ |
35 | #else |
36 | preempt_enable(); | |
37 | #endif | |
a866374a PZ |
38 | } |
39 | ||
c22ce143 HY |
40 | #ifndef ARCH_HAS_NOCACHE_UACCESS |
41 | ||
42 | static inline unsigned long __copy_from_user_inatomic_nocache(void *to, | |
43 | const void __user *from, unsigned long n) | |
44 | { | |
45 | return __copy_from_user_inatomic(to, from, n); | |
46 | } | |
47 | ||
48 | static inline unsigned long __copy_from_user_nocache(void *to, | |
49 | const void __user *from, unsigned long n) | |
50 | { | |
51 | return __copy_from_user(to, from, n); | |
52 | } | |
53 | ||
54 | #endif /* ARCH_HAS_NOCACHE_UACCESS */ | |
55 | ||
1b79e551 AM |
56 | /** |
57 | * probe_kernel_address(): safely attempt to read from a location | |
58 | * @addr: address to read from - its type is type typeof(retval)* | |
59 | * @retval: read into this variable | |
60 | * | |
61 | * Safely read from address @addr into variable @revtal. If a kernel fault | |
62 | * happens, handle that and return -EFAULT. | |
63 | * We ensure that the __get_user() is executed in atomic context so that | |
64 | * do_page_fault() doesn't attempt to take mmap_sem. This makes | |
65 | * probe_kernel_address() suitable for use within regions where the caller | |
66 | * already holds mmap_sem, or other locks which nest inside mmap_sem. | |
20aa7b21 AM |
67 | * This must be a macro because __get_user() needs to know the types of the |
68 | * args. | |
69 | * | |
70 | * We don't include enough header files to be able to do the set_fs(). We | |
71 | * require that the probe_kernel_address() caller will do that. | |
1b79e551 AM |
72 | */ |
73 | #define probe_kernel_address(addr, retval) \ | |
74 | ({ \ | |
75 | long ret; \ | |
20aa7b21 | 76 | mm_segment_t old_fs = get_fs(); \ |
1b79e551 | 77 | \ |
20aa7b21 | 78 | set_fs(KERNEL_DS); \ |
a866374a | 79 | pagefault_disable(); \ |
fb71e453 | 80 | ret = __copy_from_user_inatomic(&(retval), (__force typeof(retval) __user *)(addr), sizeof(retval)); \ |
a866374a | 81 | pagefault_enable(); \ |
20aa7b21 | 82 | set_fs(old_fs); \ |
1b79e551 AM |
83 | ret; \ |
84 | }) | |
85 | ||
c33fa9f5 IM |
86 | /* |
87 | * probe_kernel_read(): safely attempt to read from a location | |
88 | * @dst: pointer to the buffer that shall take the data | |
89 | * @src: address to read from | |
90 | * @size: size of the data chunk | |
91 | * | |
92 | * Safely read from address @src to the buffer at @dst. If a kernel fault | |
93 | * happens, handle that and return -EFAULT. | |
94 | */ | |
f29c5041 SR |
95 | extern long probe_kernel_read(void *dst, const void *src, size_t size); |
96 | extern long __probe_kernel_read(void *dst, const void *src, size_t size); | |
c33fa9f5 IM |
97 | |
98 | /* | |
99 | * probe_kernel_write(): safely attempt to write to a location | |
100 | * @dst: address to write to | |
101 | * @src: pointer to the data that shall be written | |
102 | * @size: size of the data chunk | |
103 | * | |
104 | * Safely write to address @dst from the buffer at @src. If a kernel fault | |
105 | * happens, handle that and return -EFAULT. | |
106 | */ | |
f29c5041 SR |
107 | extern long notrace probe_kernel_write(void *dst, const void *src, size_t size); |
108 | extern long notrace __probe_kernel_write(void *dst, const void *src, size_t size); | |
c33fa9f5 | 109 | |
c22ce143 | 110 | #endif /* __LINUX_UACCESS_H__ */ |