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8a625c1f NK |
1 | #ifndef _TOOLS_LINUX_COMPILER_H_ |
2 | #define _TOOLS_LINUX_COMPILER_H_ | |
5a116dd2 | 3 | |
5ac69737 ACM |
4 | /* Optimization barrier */ |
5 | /* The "volatile" is due to gcc bugs */ | |
6 | #define barrier() __asm__ __volatile__("": : :"memory") | |
7 | ||
5a116dd2 | 8 | #ifndef __always_inline |
7a10822a | 9 | # define __always_inline inline __attribute__((always_inline)) |
5a116dd2 | 10 | #endif |
7a10822a | 11 | |
8c98abff ACM |
12 | #ifdef __ANDROID__ |
13 | /* | |
14 | * FIXME: Big hammer to get rid of tons of: | |
15 | * "warning: always_inline function might not be inlinable" | |
16 | * | |
17 | * At least on android-ndk-r12/platforms/android-24/arch-arm | |
18 | */ | |
19 | #undef __always_inline | |
20 | #define __always_inline inline | |
21 | #endif | |
22 | ||
5a116dd2 | 23 | #define __user |
7a10822a | 24 | |
195bcbf5 | 25 | #ifndef __attribute_const__ |
7a10822a | 26 | # define __attribute_const__ |
195bcbf5 | 27 | #endif |
5a116dd2 | 28 | |
1d037ca1 | 29 | #ifndef __maybe_unused |
7a10822a IM |
30 | # define __maybe_unused __attribute__((unused)) |
31 | #endif | |
32 | ||
33 | #ifndef __packed | |
34 | # define __packed __attribute__((__packed__)) | |
1d037ca1 | 35 | #endif |
618038df | 36 | |
86d5a70c | 37 | #ifndef __force |
7a10822a | 38 | # define __force |
86d5a70c IT |
39 | #endif |
40 | ||
fb1c9185 IM |
41 | #ifndef __weak |
42 | # define __weak __attribute__((weak)) | |
43 | #endif | |
44 | ||
835d44b9 NK |
45 | #ifndef likely |
46 | # define likely(x) __builtin_expect(!!(x), 1) | |
47 | #endif | |
48 | ||
49 | #ifndef unlikely | |
50 | # define unlikely(x) __builtin_expect(!!(x), 0) | |
51 | #endif | |
52 | ||
73a31b7c JO |
53 | #define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x)) |
54 | ||
728abda6 ACM |
55 | #include <linux/types.h> |
56 | ||
c95f3432 JO |
57 | /* |
58 | * Following functions are taken from kernel sources and | |
59 | * break aliasing rules in their original form. | |
60 | * | |
61 | * While kernel is compiled with -fno-strict-aliasing, | |
62 | * perf uses -Wstrict-aliasing=3 which makes build fail | |
63 | * under gcc 4.4. | |
64 | * | |
65 | * Using extra __may_alias__ type to allow aliasing | |
66 | * in this case. | |
67 | */ | |
68 | typedef __u8 __attribute__((__may_alias__)) __u8_alias_t; | |
69 | typedef __u16 __attribute__((__may_alias__)) __u16_alias_t; | |
70 | typedef __u32 __attribute__((__may_alias__)) __u32_alias_t; | |
71 | typedef __u64 __attribute__((__may_alias__)) __u64_alias_t; | |
72 | ||
728abda6 ACM |
73 | static __always_inline void __read_once_size(const volatile void *p, void *res, int size) |
74 | { | |
75 | switch (size) { | |
c95f3432 JO |
76 | case 1: *(__u8_alias_t *) res = *(volatile __u8_alias_t *) p; break; |
77 | case 2: *(__u16_alias_t *) res = *(volatile __u16_alias_t *) p; break; | |
78 | case 4: *(__u32_alias_t *) res = *(volatile __u32_alias_t *) p; break; | |
79 | case 8: *(__u64_alias_t *) res = *(volatile __u64_alias_t *) p; break; | |
728abda6 ACM |
80 | default: |
81 | barrier(); | |
82 | __builtin_memcpy((void *)res, (const void *)p, size); | |
83 | barrier(); | |
84 | } | |
85 | } | |
86 | ||
87 | static __always_inline void __write_once_size(volatile void *p, void *res, int size) | |
88 | { | |
89 | switch (size) { | |
c95f3432 JO |
90 | case 1: *(volatile __u8_alias_t *) p = *(__u8_alias_t *) res; break; |
91 | case 2: *(volatile __u16_alias_t *) p = *(__u16_alias_t *) res; break; | |
92 | case 4: *(volatile __u32_alias_t *) p = *(__u32_alias_t *) res; break; | |
93 | case 8: *(volatile __u64_alias_t *) p = *(__u64_alias_t *) res; break; | |
728abda6 ACM |
94 | default: |
95 | barrier(); | |
96 | __builtin_memcpy((void *)p, (const void *)res, size); | |
97 | barrier(); | |
98 | } | |
99 | } | |
100 | ||
101 | /* | |
102 | * Prevent the compiler from merging or refetching reads or writes. The | |
103 | * compiler is also forbidden from reordering successive instances of | |
104 | * READ_ONCE, WRITE_ONCE and ACCESS_ONCE (see below), but only when the | |
105 | * compiler is aware of some particular ordering. One way to make the | |
106 | * compiler aware of ordering is to put the two invocations of READ_ONCE, | |
107 | * WRITE_ONCE or ACCESS_ONCE() in different C statements. | |
108 | * | |
109 | * In contrast to ACCESS_ONCE these two macros will also work on aggregate | |
110 | * data types like structs or unions. If the size of the accessed data | |
111 | * type exceeds the word size of the machine (e.g., 32 bits or 64 bits) | |
112 | * READ_ONCE() and WRITE_ONCE() will fall back to memcpy and print a | |
113 | * compile-time warning. | |
114 | * | |
115 | * Their two major use cases are: (1) Mediating communication between | |
116 | * process-level code and irq/NMI handlers, all running on the same CPU, | |
117 | * and (2) Ensuring that the compiler does not fold, spindle, or otherwise | |
118 | * mutilate accesses that either do not require ordering or that interact | |
119 | * with an explicit memory barrier or atomic instruction that provides the | |
120 | * required ordering. | |
121 | */ | |
122 | ||
123 | #define READ_ONCE(x) \ | |
124 | ({ union { typeof(x) __val; char __c[1]; } __u; __read_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) | |
125 | ||
126 | #define WRITE_ONCE(x, val) \ | |
127 | ({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; __write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; }) | |
128 | ||
8a625c1f | 129 | #endif /* _TOOLS_LINUX_COMPILER_H */ |