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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 | |
d0ee69ff MD |
35 | /* |
36 | * SIDE_PARAM_SELECT_ARG1 | |
37 | * | |
38 | * Select second argument. Use inside macros to implement optional last | |
39 | * macro argument, such as: | |
40 | * | |
41 | * #define macro(_a, _b, _c, _optional...) \ | |
42 | * SIDE_PARAM_SELECT_ARG1(_, ##_optional, do_default_macro()) | |
43 | * | |
44 | * This macro is far from pretty, but attempts to create a cleaner layer | |
45 | * on top fails for various reasons: | |
46 | * | |
47 | * - The libside API needs to use the default argument selection as an | |
48 | * argument to itself (recursively), e.g. for fields and for types, so | |
49 | * using the argument selection within an extra layer of macro fails | |
50 | * because the extra layer cannot expand recursively. | |
51 | * - Attempts to make the extra layer of macro support recursion through | |
52 | * another layer of macros which expands all arguments failed because | |
53 | * the optional argument may contain commas, and is therefore expanded | |
54 | * into multiple arguments before argument selection, which fails to | |
55 | * select the optional argument content after its first comma. | |
56 | */ | |
57 | #define SIDE_PARAM_SELECT_ARG1(_arg0, _arg1, ...) _arg1 | |
58 | ||
2e197497 MD |
59 | /* |
60 | * Compile time assertion. | |
61 | * - predicate: boolean expression to evaluate, | |
62 | * - msg: string to print to the user on failure when `static_assert()` is | |
63 | * supported, | |
64 | * - c_identifier_msg: message to be included in the typedef to emulate a | |
65 | * static assertion. This parameter must be a valid C identifier as it will | |
66 | * be used as a typedef name. | |
67 | */ | |
68 | #ifdef __cplusplus | |
69 | #define side_static_assert(predicate, msg, c_identifier_msg) \ | |
70 | static_assert(predicate, msg) | |
71 | #elif defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L) | |
72 | #define side_static_assert(predicate, msg, c_identifier_msg) \ | |
73 | _Static_assert(predicate, msg) | |
74 | #else | |
75 | /* | |
76 | * Evaluates the predicate and emit a compilation error on failure. | |
77 | * | |
78 | * If the predicate evaluates to true, this macro emits a function | |
79 | * prototype with an argument type which is an array of size 0. | |
80 | * | |
81 | * If the predicate evaluates to false, this macro emits a function | |
82 | * prototype with an argument type which is an array of negative size | |
83 | * which is invalid in C and forces a compiler error. The | |
84 | * c_identifier_msg parameter is used as the argument identifier so it | |
85 | * is printed to the user when the error is reported. | |
86 | */ | |
87 | #define side_static_assert(predicate, msg, c_identifier_msg) \ | |
88 | void side_static_assert_proto(char c_identifier_msg[2*!!(predicate)-1]) | |
89 | #endif | |
90 | ||
b59abc69 | 91 | /* |
67337c4a | 92 | * side_container_of - Get the address of an object containing a field. |
b59abc69 MD |
93 | * |
94 | * @ptr: pointer to the field. | |
95 | * @type: type of the object. | |
96 | * @member: name of the field within the object. | |
97 | */ | |
67337c4a | 98 | #define side_container_of(ptr, type, member) \ |
b59abc69 MD |
99 | __extension__ \ |
100 | ({ \ | |
101 | const __typeof__(((type *) NULL)->member) * __ptr = (ptr); \ | |
102 | (type *)((char *)__ptr - offsetof(type, member)); \ | |
103 | }) | |
104 | ||
67337c4a | 105 | #define side_struct_field_sizeof(_struct, _field) \ |
88bab79c | 106 | sizeof(((_struct * )NULL)->_field) |
8e87e437 | 107 | |
2e197497 MD |
108 | #define SIDE_PACKED __attribute__((packed)) |
109 | ||
110 | #define side_padding(bytes) char padding[bytes] | |
111 | ||
112 | #define side_check_size(_type, _len) \ | |
113 | side_static_assert(sizeof(_type) == (_len), \ | |
114 | "Unexpected size for type: `" #_type "`", \ | |
115 | unexpected_size_for_type_##_type) | |
116 | ||
117 | #if (SIDE_BYTE_ORDER == SIDE_LITTLE_ENDIAN) | |
118 | #define SIDE_ENDIAN_ORDER(_low, _high) _low, _high | |
f61301bb | 119 | #else |
2e197497 | 120 | #define SIDE_ENDIAN_ORDER(_low, _high) _high, _low |
f61301bb MD |
121 | #endif |
122 | ||
326c676c MD |
123 | /* |
124 | * The side_ptr macros allow defining a pointer type which is suitable | |
2e197497 MD |
125 | * for use by 32-bit, 64-bit and 128-bit kernels without compatibility |
126 | * code, while preserving information about the pointer type. | |
326c676c | 127 | * |
2e197497 MD |
128 | * Those pointers are stored as 128-bit integers, and the type of the |
129 | * actual pointer is kept alongside with the 128-bit pointer value in a | |
326c676c | 130 | * 0-len array within a union. |
326c676c MD |
131 | */ |
132 | #if (__SIZEOF_POINTER__ <= 8) | |
2e197497 | 133 | # define side_raw_ptr_t(_type) \ |
326c676c | 134 | union { \ |
2e197497 MD |
135 | struct { \ |
136 | uint64_t SIDE_ENDIAN_ORDER(low, high); \ | |
137 | } v; \ | |
138 | struct { \ | |
139 | _type t[0]; \ | |
140 | } SIDE_PACKED s; \ | |
141 | side_padding(16); \ | |
326c676c MD |
142 | } |
143 | # define side_ptr_get(_field) \ | |
2e197497 | 144 | ((__typeof__((_field).s.t[0]))(uintptr_t)(_field).v.low) |
326c676c MD |
145 | # define side_ptr_set(_field, _ptr) \ |
146 | do { \ | |
2e197497 MD |
147 | (_field).v.low = (uint64_t)(uintptr_t)(_ptr); \ |
148 | (_field).v.high = 0; \ | |
326c676c | 149 | } while (0) |
2e197497 MD |
150 | |
151 | /* Keep the correct field init order to make old g++ happy. */ | |
152 | # if (SIDE_BYTE_ORDER == SIDE_LITTLE_ENDIAN) | |
153 | # define SIDE_PTR_INIT(...) \ | |
154 | { \ | |
155 | .v = { \ | |
156 | .low = (uintptr_t) (__VA_ARGS__), \ | |
157 | .high = 0, \ | |
158 | }, \ | |
159 | } | |
160 | # else | |
161 | # define SIDE_PTR_INIT(...) \ | |
162 | { \ | |
163 | .v = { \ | |
164 | .high = 0, \ | |
165 | .low = (uintptr_t) (__VA_ARGS__), \ | |
166 | }, \ | |
167 | } | |
168 | # endif | |
169 | #elif (__SIZEOF_POINTER__ == 16) | |
170 | # define side_raw_ptr_t(_type) \ | |
326c676c MD |
171 | union { \ |
172 | uintptr_t v; \ | |
2e197497 MD |
173 | struct { \ |
174 | _type t[0]; \ | |
175 | } SIDE_PACKED s; \ | |
176 | side_padding(16); \ | |
326c676c MD |
177 | } |
178 | # define side_ptr_get(_field) \ | |
2e197497 | 179 | ((__typeof__((_field).s.t[0]))(_field).v) |
326c676c MD |
180 | # define side_ptr_set(_field, _ptr) \ |
181 | do { \ | |
182 | (_field).v = (uintptr_t)(_ptr); \ | |
183 | } while (0) | |
2e197497 MD |
184 | # define SIDE_PTR_INIT(...) { .v = (uintptr_t) (__VA_ARGS__) } |
185 | #else | |
186 | # error "Unsupported pointer size" | |
326c676c MD |
187 | #endif |
188 | ||
2e197497 MD |
189 | #define side_ptr_t(_type) side_raw_ptr_t(_type *) |
190 | #define side_func_ptr_t(_type) side_raw_ptr_t(_type) | |
191 | ||
192 | side_static_assert(sizeof(side_ptr_t(int)) == 16, | |
193 | "Unexpected size for side_ptr_t", | |
194 | unexpected_size_side_ptr_t); | |
0e2cd351 | 195 | |
f2a90e2a MD |
196 | /* |
197 | * side_enum_t allows defining fixed-sized enumerations while preserving | |
198 | * typing information. | |
199 | */ | |
200 | #define side_enum_t(_enum_type, _size_type) \ | |
201 | union { \ | |
202 | _size_type v; \ | |
2e197497 MD |
203 | struct { \ |
204 | _enum_type t[0]; \ | |
205 | } SIDE_PACKED s; \ | |
f2a90e2a MD |
206 | } |
207 | ||
208 | #define side_enum_get(_field) \ | |
2e197497 | 209 | ((__typeof__((_field).s.t[0]))(_field).v) |
f2a90e2a MD |
210 | |
211 | #define side_enum_set(_field, _v) \ | |
212 | do { \ | |
213 | (_field).v = (_v); \ | |
214 | } while (0) | |
215 | ||
216 | #define SIDE_ENUM_INIT(...) { .v = (__VA_ARGS__) } | |
217 | ||
67337c4a | 218 | #endif /* _SIDE_MACROS_H */ |