1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _TOOLS_LINUX_COMPILER_H_
3 #define _TOOLS_LINUX_COMPILER_H_
4
5 #ifndef __ASSEMBLY__
6
7 #include <linux/compiler_types.h>
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 __always_unused
48 #define __always_unused __attribute__((__unused__))
49 #endif
50
51 #ifndef __noreturn
52 #define __noreturn __attribute__((__noreturn__))
53 #endif
54
55 #ifndef unreachable
56 #define unreachable() __builtin_unreachable()
57 #endif
58
59 #ifndef noinline
60 #define noinline
61 #endif
62
63 #ifndef __nocf_check
64 #define __nocf_check __attribute__((nocf_check))
65 #endif
66
67 #ifndef __naked
68 #define __naked __attribute__((__naked__))
69 #endif
70
71 /* Are two types/vars the same type (ignoring qualifiers)? */
72 #ifndef __same_type
73 # define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
74 #endif
75
76 /*
77 * This returns a constant expression while determining if an argument is
78 * a constant expression, most importantly without evaluating the argument.
79 * Glory to Martin Uecker <Martin.Uecker@med.uni-goettingen.de>
80 */
81 #define __is_constexpr(x) \
82 (sizeof(int) == sizeof(*(8 ? ((void *)((long)(x) * 0l)) : (int *)8)))
83
84 #ifdef __ANDROID__
85 /*
86 * FIXME: Big hammer to get rid of tons of:
87 * "warning: always_inline function might not be inlinable"
88 *
89 * At least on android-ndk-r12/platforms/android-24/arch-arm
90 */
91 #undef __always_inline
92 #define __always_inline inline
93 #endif
94
95 #define __user
96 #define __rcu
97 #define __read_mostly
98
99 #ifndef __attribute_const__
100 # define __attribute_const__
101 #endif
102
103 #ifndef __maybe_unused
104 # define __maybe_unused __attribute__((unused))
105 #endif
106
107 #ifndef __used
108 # define __used __attribute__((__unused__))
109 #endif
110
111 #ifndef __packed
112 # define __packed __attribute__((__packed__))
113 #endif
114
115 #ifndef __force
116 # define __force
117 #endif
118
119 #ifndef __weak
120 # define __weak __attribute__((weak))
121 #endif
122
123 #ifndef likely
124 # define likely(x) __builtin_expect(!!(x), 1)
125 #endif
126
127 #ifndef unlikely
128 # define unlikely(x) __builtin_expect(!!(x), 0)
129 #endif
130
131 #include <linux/types.h>
132
133 /*
134 * Following functions are taken from kernel sources and
135 * break aliasing rules in their original form.
136 *
137 * While kernel is compiled with -fno-strict-aliasing,
138 * perf uses -Wstrict-aliasing=3 which makes build fail
139 * under gcc 4.4.
140 *
141 * Using extra __may_alias__ type to allow aliasing
142 * in this case.
143 */
144 typedef __u8 __attribute__((__may_alias__)) __u8_alias_t;
145 typedef __u16 __attribute__((__may_alias__)) __u16_alias_t;
146 typedef __u32 __attribute__((__may_alias__)) __u32_alias_t;
147 typedef __u64 __attribute__((__may_alias__)) __u64_alias_t;
148
__read_once_size(const volatile void * p,void * res,int size)149 static __always_inline void __read_once_size(const volatile void *p, void *res, int size)
150 {
151 switch (size) {
152 case 1: *(__u8_alias_t *) res = *(volatile __u8_alias_t *) p; break;
153 case 2: *(__u16_alias_t *) res = *(volatile __u16_alias_t *) p; break;
154 case 4: *(__u32_alias_t *) res = *(volatile __u32_alias_t *) p; break;
155 case 8: *(__u64_alias_t *) res = *(volatile __u64_alias_t *) p; break;
156 default:
157 barrier();
158 __builtin_memcpy((void *)res, (const void *)p, size);
159 barrier();
160 }
161 }
162
__write_once_size(volatile void * p,void * res,int size)163 static __always_inline void __write_once_size(volatile void *p, void *res, int size)
164 {
165 switch (size) {
166 case 1: *(volatile __u8_alias_t *) p = *(__u8_alias_t *) res; break;
167 case 2: *(volatile __u16_alias_t *) p = *(__u16_alias_t *) res; break;
168 case 4: *(volatile __u32_alias_t *) p = *(__u32_alias_t *) res; break;
169 case 8: *(volatile __u64_alias_t *) p = *(__u64_alias_t *) res; break;
170 default:
171 barrier();
172 __builtin_memcpy((void *)p, (const void *)res, size);
173 barrier();
174 }
175 }
176
177 /*
178 * Prevent the compiler from merging or refetching reads or writes. The
179 * compiler is also forbidden from reordering successive instances of
180 * READ_ONCE and WRITE_ONCE, but only when the compiler is aware of some
181 * particular ordering. One way to make the compiler aware of ordering is to
182 * put the two invocations of READ_ONCE or WRITE_ONCE in different C
183 * statements.
184 *
185 * These two macros will also work on aggregate data types like structs or
186 * unions. If the size of the accessed data type exceeds the word size of
187 * the machine (e.g., 32 bits or 64 bits) READ_ONCE() and WRITE_ONCE() will
188 * fall back to memcpy and print a compile-time warning.
189 *
190 * Their two major use cases are: (1) Mediating communication between
191 * process-level code and irq/NMI handlers, all running on the same CPU,
192 * and (2) Ensuring that the compiler does not fold, spindle, or otherwise
193 * mutilate accesses that either do not require ordering or that interact
194 * with an explicit memory barrier or atomic instruction that provides the
195 * required ordering.
196 */
197
198 #define READ_ONCE(x) \
199 ({ \
200 union { typeof(x) __val; char __c[1]; } __u = \
201 { .__c = { 0 } }; \
202 __read_once_size(&(x), __u.__c, sizeof(x)); \
203 __u.__val; \
204 })
205
206 #define WRITE_ONCE(x, val) \
207 ({ \
208 union { typeof(x) __val; char __c[1]; } __u = \
209 { .__val = (val) }; \
210 __write_once_size(&(x), __u.__c, sizeof(x)); \
211 __u.__val; \
212 })
213
214
215 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */
216 #define ___PASTE(a, b) a##b
217 #define __PASTE(a, b) ___PASTE(a, b)
218
219 #ifndef OPTIMIZER_HIDE_VAR
220 /* Make the optimizer believe the variable can be manipulated arbitrarily. */
221 #define OPTIMIZER_HIDE_VAR(var) \
222 __asm__ ("" : "=r" (var) : "0" (var))
223 #endif
224
225 #endif /* __ASSEMBLY__ */
226
227 #endif /* _TOOLS_LINUX_COMPILER_H */
228