Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _TOOLS_LINUX_COMPILER_H_
3#define _TOOLS_LINUX_COMPILER_H_
4
5#ifdef __GNUC__
6#include <linux/compiler-gcc.h>
7#endif
8
9#ifndef __compiletime_error
10# define __compiletime_error(message)
11#endif
12
13#ifdef __OPTIMIZE__
14# define __compiletime_assert(condition, msg, prefix, suffix) \
15 do { \
16 extern void prefix ## suffix(void) __compiletime_error(msg); \
17 if (!(condition)) \
18 prefix ## suffix(); \
19 } while (0)
20#else
21# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
22#endif
23
24#define _compiletime_assert(condition, msg, prefix, suffix) \
25 __compiletime_assert(condition, msg, prefix, suffix)
26
27/**
28 * compiletime_assert - break build and emit msg if condition is false
29 * @condition: a compile-time constant condition to check
30 * @msg: a message to emit if condition is false
31 *
32 * In tradition of POSIX assert, this macro will break the build if the
33 * supplied condition is *false*, emitting the supplied error message if the
34 * compiler has support to do so.
35 */
36#define compiletime_assert(condition, msg) \
37 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
38
39/* Optimization barrier */
40/* The "volatile" is due to gcc bugs */
41#define barrier() __asm__ __volatile__("": : :"memory")
42
43#ifndef __always_inline
44# define __always_inline inline __attribute__((always_inline))
45#endif
46
47#ifndef noinline
48#define noinline
49#endif
50
51/* Are two types/vars the same type (ignoring qualifiers)? */
52#ifndef __same_type
53# define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
54#endif
55
56#ifdef __ANDROID__
57/*
58 * FIXME: Big hammer to get rid of tons of:
59 * "warning: always_inline function might not be inlinable"
60 *
61 * At least on android-ndk-r12/platforms/android-24/arch-arm
62 */
63#undef __always_inline
64#define __always_inline inline
65#endif
66
67#define __user
68#define __rcu
69#define __read_mostly
70
71#ifndef __attribute_const__
72# define __attribute_const__
73#endif
74
75#ifndef __maybe_unused
76# define __maybe_unused __attribute__((unused))
77#endif
78
79#ifndef __used
80# define __used __attribute__((__unused__))
81#endif
82
83#ifndef __packed
84# define __packed __attribute__((__packed__))
85#endif
86
87#ifndef __force
88# define __force
89#endif
90
91#ifndef __weak
92# define __weak __attribute__((weak))
93#endif
94
95#ifndef likely
96# define likely(x) __builtin_expect(!!(x), 1)
97#endif
98
99#ifndef unlikely
100# define unlikely(x) __builtin_expect(!!(x), 0)
101#endif
102
103#ifndef __init
104# define __init
105#endif
106
107#ifndef noinline
108# define noinline
109#endif
110
111#include <linux/types.h>
112
113/*
114 * Following functions are taken from kernel sources and
115 * break aliasing rules in their original form.
116 *
117 * While kernel is compiled with -fno-strict-aliasing,
118 * perf uses -Wstrict-aliasing=3 which makes build fail
119 * under gcc 4.4.
120 *
121 * Using extra __may_alias__ type to allow aliasing
122 * in this case.
123 */
124typedef __u8 __attribute__((__may_alias__)) __u8_alias_t;
125typedef __u16 __attribute__((__may_alias__)) __u16_alias_t;
126typedef __u32 __attribute__((__may_alias__)) __u32_alias_t;
127typedef __u64 __attribute__((__may_alias__)) __u64_alias_t;
128
129static __always_inline void __read_once_size(const volatile void *p, void *res, int size)
130{
131 switch (size) {
132 case 1: *(__u8_alias_t *) res = *(volatile __u8_alias_t *) p; break;
133 case 2: *(__u16_alias_t *) res = *(volatile __u16_alias_t *) p; break;
134 case 4: *(__u32_alias_t *) res = *(volatile __u32_alias_t *) p; break;
135 case 8: *(__u64_alias_t *) res = *(volatile __u64_alias_t *) p; break;
136 default:
137 barrier();
138 __builtin_memcpy((void *)res, (const void *)p, size);
139 barrier();
140 }
141}
142
143static __always_inline void __write_once_size(volatile void *p, void *res, int size)
144{
145 switch (size) {
146 case 1: *(volatile __u8_alias_t *) p = *(__u8_alias_t *) res; break;
147 case 2: *(volatile __u16_alias_t *) p = *(__u16_alias_t *) res; break;
148 case 4: *(volatile __u32_alias_t *) p = *(__u32_alias_t *) res; break;
149 case 8: *(volatile __u64_alias_t *) p = *(__u64_alias_t *) res; break;
150 default:
151 barrier();
152 __builtin_memcpy((void *)p, (const void *)res, size);
153 barrier();
154 }
155}
156
157/*
158 * Prevent the compiler from merging or refetching reads or writes. The
159 * compiler is also forbidden from reordering successive instances of
160 * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some
161 * particular ordering. One way to make the compiler aware of ordering is to
162 * put the two invocations of READ_ONCE or WRITE_ONCE in different C
163 * statements.
164 *
165 * These two macros will also work on aggregate data types like structs or
166 * unions. If the size of the accessed data type exceeds the word size of
167 * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will
168 * fall back to memcpy and print a compile-time warning.
169 *
170 * Their two major use cases are: (1) Mediating communication between
171 * process-level code and irq/NMI handlers, all running on the same CPU,
172 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
173 * mutilate accesses that either do not require ordering or that interact
174 * with an explicit memory barrier or atomic instruction that provides the
175 * required ordering.
176 */
177
178#define READ_ONCE(x) \
179({ \
180 union { typeof(x) __val; char __c[1]; } __u = \
181 { .__c = { 0 } }; \
182 __read_once_size(&(x), __u.__c, sizeof(x)); \
183 __u.__val; \
184})
185
186#define WRITE_ONCE(x, val) \
187({ \
188 union { typeof(x) __val; char __c[1]; } __u = \
189 { .__val = (val) }; \
190 __write_once_size(&(x), __u.__c, sizeof(x)); \
191 __u.__val; \
192})
193
194
195#ifndef __fallthrough
196# define __fallthrough
197#endif
198
199/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
200#define ___PASTE(a, b) a##b
201#define __PASTE(a, b) ___PASTE(a, b)
202
203#endif /* _TOOLS_LINUX_COMPILER_H */