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f611d0c3 MD |
1 | // SPDX-License-Identifier: MIT |
2 | /* | |
3 | * Copyright 2022 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
4 | */ | |
5 | ||
67337c4a MD |
6 | #ifndef _SIDE_MACROS_H |
7 | #define _SIDE_MACROS_H | |
f611d0c3 | 8 | |
6e46f5e6 | 9 | #include <stddef.h> |
8e87e437 | 10 | #include <limits.h> |
2e197497 MD |
11 | #include <stdint.h> |
12 | #include <side/endian.h> | |
6e46f5e6 | 13 | |
f611d0c3 MD |
14 | /* Helper macros */ |
15 | ||
67337c4a | 16 | #define SIDE_ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0])) |
f611d0c3 MD |
17 | |
18 | /* | |
67337c4a | 19 | * Compound literals with static storage are needed by SIDE |
f611d0c3 MD |
20 | * instrumentation. |
21 | * Compound literals are part of the C99 and C11 standards, but not | |
22 | * part of the C++ standards. They are supported by most C++ compilers | |
23 | * though. | |
24 | * | |
25 | * Example use: | |
26 | * static struct mystruct *var = LTTNG_UST_COMPOUND_LITERAL(struct mystruct, { 1, 2, 3 }); | |
27 | */ | |
67337c4a | 28 | #define SIDE_COMPOUND_LITERAL(type, ...) (type[]) { __VA_ARGS__ } |
f611d0c3 | 29 | |
67337c4a MD |
30 | #define side_likely(x) __builtin_expect(!!(x), 1) |
31 | #define side_unlikely(x) __builtin_expect(!!(x), 0) | |
f611d0c3 | 32 | |
67337c4a | 33 | #define SIDE_PARAM(...) __VA_ARGS__ |
f611d0c3 | 34 | |
441235e7 MD |
35 | #define side_offsetofend(type, member) \ |
36 | (offsetof(type, member) + sizeof(((type *)0)->member)) | |
37 | ||
d0ee69ff MD |
38 | /* |
39 | * SIDE_PARAM_SELECT_ARG1 | |
40 | * | |
41 | * Select second argument. Use inside macros to implement optional last | |
42 | * macro argument, such as: | |
43 | * | |
44 | * #define macro(_a, _b, _c, _optional...) \ | |
45 | * SIDE_PARAM_SELECT_ARG1(_, ##_optional, do_default_macro()) | |
46 | * | |
47 | * This macro is far from pretty, but attempts to create a cleaner layer | |
48 | * on top fails for various reasons: | |
49 | * | |
50 | * - The libside API needs to use the default argument selection as an | |
51 | * argument to itself (recursively), e.g. for fields and for types, so | |
52 | * using the argument selection within an extra layer of macro fails | |
53 | * because the extra layer cannot expand recursively. | |
54 | * - Attempts to make the extra layer of macro support recursion through | |
55 | * another layer of macros which expands all arguments failed because | |
56 | * the optional argument may contain commas, and is therefore expanded | |
57 | * into multiple arguments before argument selection, which fails to | |
58 | * select the optional argument content after its first comma. | |
59 | */ | |
60 | #define SIDE_PARAM_SELECT_ARG1(_arg0, _arg1, ...) _arg1 | |
61 | ||
2e197497 MD |
62 | /* |
63 | * Compile time assertion. | |
64 | * - predicate: boolean expression to evaluate, | |
65 | * - msg: string to print to the user on failure when `static_assert()` is | |
66 | * supported, | |
67 | * - c_identifier_msg: message to be included in the typedef to emulate a | |
68 | * static assertion. This parameter must be a valid C identifier as it will | |
69 | * be used as a typedef name. | |
70 | */ | |
71 | #ifdef __cplusplus | |
72 | #define side_static_assert(predicate, msg, c_identifier_msg) \ | |
73 | static_assert(predicate, msg) | |
74 | #elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L) | |
75 | #define side_static_assert(predicate, msg, c_identifier_msg) \ | |
76 | _Static_assert(predicate, msg) | |
77 | #else | |
78 | /* | |
79 | * Evaluates the predicate and emit a compilation error on failure. | |
80 | * | |
81 | * If the predicate evaluates to true, this macro emits a function | |
82 | * prototype with an argument type which is an array of size 0. | |
83 | * | |
84 | * If the predicate evaluates to false, this macro emits a function | |
85 | * prototype with an argument type which is an array of negative size | |
86 | * which is invalid in C and forces a compiler error. The | |
87 | * c_identifier_msg parameter is used as the argument identifier so it | |
88 | * is printed to the user when the error is reported. | |
89 | */ | |
90 | #define side_static_assert(predicate, msg, c_identifier_msg) \ | |
91 | void side_static_assert_proto(char c_identifier_msg[2*!!(predicate)-1]) | |
92 | #endif | |
93 | ||
b59abc69 | 94 | /* |
67337c4a | 95 | * side_container_of - Get the address of an object containing a field. |
b59abc69 MD |
96 | * |
97 | * @ptr: pointer to the field. | |
98 | * @type: type of the object. | |
99 | * @member: name of the field within the object. | |
100 | */ | |
67337c4a | 101 | #define side_container_of(ptr, type, member) \ |
b59abc69 MD |
102 | __extension__ \ |
103 | ({ \ | |
104 | const __typeof__(((type *) NULL)->member) * __ptr = (ptr); \ | |
105 | (type *)((char *)__ptr - offsetof(type, member)); \ | |
106 | }) | |
107 | ||
67337c4a | 108 | #define side_struct_field_sizeof(_struct, _field) \ |
88bab79c | 109 | sizeof(((_struct * )NULL)->_field) |
8e87e437 | 110 | |
2e197497 MD |
111 | #define SIDE_PACKED __attribute__((packed)) |
112 | ||
113 | #define side_padding(bytes) char padding[bytes] | |
114 | ||
115 | #define side_check_size(_type, _len) \ | |
116 | side_static_assert(sizeof(_type) == (_len), \ | |
117 | "Unexpected size for type: `" #_type "`", \ | |
118 | unexpected_size_for_type_##_type) | |
119 | ||
326c676c MD |
120 | /* |
121 | * The side_ptr macros allow defining a pointer type which is suitable | |
2e197497 MD |
122 | * for use by 32-bit, 64-bit and 128-bit kernels without compatibility |
123 | * code, while preserving information about the pointer type. | |
326c676c | 124 | * |
2e197497 MD |
125 | * Those pointers are stored as 128-bit integers, and the type of the |
126 | * actual pointer is kept alongside with the 128-bit pointer value in a | |
326c676c | 127 | * 0-len array within a union. |
326c676c | 128 | */ |
a0c2ee26 MD |
129 | |
130 | #if (SIDE_BYTE_ORDER == SIDE_LITTLE_ENDIAN) | |
131 | # define SIDE_U128_PTR_IDX(n) (n) | |
132 | #else | |
133 | # define SIDE_U128_PTR_IDX(n) ((16 / __SIZEOF_POINTER__) - (n) - 1) | |
134 | #endif | |
135 | ||
136 | #define side_raw_ptr_t(_type) \ | |
326c676c | 137 | union { \ |
a0c2ee26 | 138 | _type v[16 / __SIZEOF_POINTER__]; \ |
326c676c | 139 | } |
a0c2ee26 | 140 | |
9ed8d6be | 141 | /* side_ptr_get() can be used as rvalue or lvalue. */ |
a0c2ee26 MD |
142 | #define side_ptr_get(_field) (_field).v[SIDE_U128_PTR_IDX(0)] |
143 | ||
144 | #if (__SIZEOF_POINTER__ == 4) | |
326c676c MD |
145 | # define side_ptr_set(_field, _ptr) \ |
146 | do { \ | |
a0c2ee26 MD |
147 | (_field).v[SIDE_U128_PTR_IDX(0)] = (_ptr); \ |
148 | (_field).v[SIDE_U128_PTR_IDX(1)] = 0; \ | |
149 | (_field).v[SIDE_U128_PTR_IDX(2)] = 0; \ | |
150 | (_field).v[SIDE_U128_PTR_IDX(3)] = 0; \ | |
326c676c | 151 | } while (0) |
2e197497 MD |
152 | |
153 | /* Keep the correct field init order to make old g++ happy. */ | |
154 | # if (SIDE_BYTE_ORDER == SIDE_LITTLE_ENDIAN) | |
155 | # define SIDE_PTR_INIT(...) \ | |
156 | { \ | |
157 | .v = { \ | |
a0c2ee26 MD |
158 | [0] = (__VA_ARGS__), \ |
159 | [1] = 0, \ | |
160 | [2] = 0, \ | |
161 | [3] = 0, \ | |
2e197497 MD |
162 | }, \ |
163 | } | |
164 | # else | |
165 | # define SIDE_PTR_INIT(...) \ | |
166 | { \ | |
167 | .v = { \ | |
a0c2ee26 MD |
168 | [0] = 0, \ |
169 | [1] = 0, \ | |
170 | [2] = 0, \ | |
171 | [3] = (__VA_ARGS__), \ | |
2e197497 MD |
172 | }, \ |
173 | } | |
174 | # endif | |
a0c2ee26 MD |
175 | #elif (__SIZEOF_POINTER__ == 8) |
176 | # define side_ptr_set(_field, _ptr) \ | |
177 | do { \ | |
178 | (_field).v[SIDE_U128_PTR_IDX(0)] = (_ptr); \ | |
179 | (_field).v[SIDE_U128_PTR_IDX(1)] = 0; \ | |
180 | } while (0) | |
181 | ||
182 | /* Keep the correct field init order to make old g++ happy. */ | |
183 | # if (SIDE_BYTE_ORDER == SIDE_LITTLE_ENDIAN) | |
184 | # define SIDE_PTR_INIT(...) \ | |
185 | { \ | |
186 | .v = { \ | |
187 | [0] = (__VA_ARGS__), \ | |
188 | [1] = 0, \ | |
189 | }, \ | |
326c676c | 190 | } |
a0c2ee26 MD |
191 | # else |
192 | # define SIDE_PTR_INIT(...) \ | |
193 | { \ | |
194 | .v = { \ | |
195 | [0] = 0, \ | |
196 | [1] = (__VA_ARGS__), \ | |
197 | }, \ | |
198 | } | |
199 | # endif | |
200 | #elif (__SIZEOF_POINTER__ == 16) | |
326c676c MD |
201 | # define side_ptr_set(_field, _ptr) \ |
202 | do { \ | |
a0c2ee26 | 203 | (_field).v[SIDE_U128_PTR_IDX(0)] = (_ptr); \ |
326c676c | 204 | } while (0) |
a0c2ee26 MD |
205 | |
206 | # define SIDE_PTR_INIT(...) \ | |
207 | { \ | |
208 | .v = { \ | |
209 | [0] = (__VA_ARGS__), \ | |
210 | }, \ | |
211 | } | |
2e197497 MD |
212 | #else |
213 | # error "Unsupported pointer size" | |
326c676c MD |
214 | #endif |
215 | ||
2e197497 MD |
216 | #define side_ptr_t(_type) side_raw_ptr_t(_type *) |
217 | #define side_func_ptr_t(_type) side_raw_ptr_t(_type) | |
218 | ||
219 | side_static_assert(sizeof(side_ptr_t(int)) == 16, | |
220 | "Unexpected size for side_ptr_t", | |
221 | unexpected_size_side_ptr_t); | |
0e2cd351 | 222 | |
f2a90e2a MD |
223 | /* |
224 | * side_enum_t allows defining fixed-sized enumerations while preserving | |
225 | * typing information. | |
226 | */ | |
227 | #define side_enum_t(_enum_type, _size_type) \ | |
228 | union { \ | |
229 | _size_type v; \ | |
2e197497 MD |
230 | struct { \ |
231 | _enum_type t[0]; \ | |
232 | } SIDE_PACKED s; \ | |
f2a90e2a MD |
233 | } |
234 | ||
235 | #define side_enum_get(_field) \ | |
2e197497 | 236 | ((__typeof__((_field).s.t[0]))(_field).v) |
f2a90e2a MD |
237 | |
238 | #define side_enum_set(_field, _v) \ | |
239 | do { \ | |
240 | (_field).v = (_v); \ | |
241 | } while (0) | |
242 | ||
243 | #define SIDE_ENUM_INIT(...) { .v = (__VA_ARGS__) } | |
244 | ||
67337c4a | 245 | #endif /* _SIDE_MACROS_H */ |