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62fde541 TH |
1 | /* |
2 | * linux/percpu-defs.h - basic definitions for percpu areas | |
3 | * | |
4 | * DO NOT INCLUDE DIRECTLY OUTSIDE PERCPU IMPLEMENTATION PROPER. | |
5 | * | |
6 | * This file is separate from linux/percpu.h to avoid cyclic inclusion | |
7 | * dependency from arch header files. Only to be included from | |
8 | * asm/percpu.h. | |
9 | * | |
10 | * This file includes macros necessary to declare percpu sections and | |
11 | * variables, and definitions of percpu accessors and operations. It | |
12 | * should provide enough percpu features to arch header files even when | |
13 | * they can only include asm/percpu.h to avoid cyclic inclusion dependency. | |
14 | */ | |
15 | ||
5028eaa9 DH |
16 | #ifndef _LINUX_PERCPU_DEFS_H |
17 | #define _LINUX_PERCPU_DEFS_H | |
18 | ||
62fde541 TH |
19 | #ifdef CONFIG_SMP |
20 | ||
21 | #ifdef MODULE | |
22 | #define PER_CPU_SHARED_ALIGNED_SECTION "" | |
23 | #define PER_CPU_ALIGNED_SECTION "" | |
24 | #else | |
25 | #define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned" | |
26 | #define PER_CPU_ALIGNED_SECTION "..shared_aligned" | |
27 | #endif | |
28 | #define PER_CPU_FIRST_SECTION "..first" | |
29 | ||
30 | #else | |
31 | ||
32 | #define PER_CPU_SHARED_ALIGNED_SECTION "" | |
33 | #define PER_CPU_ALIGNED_SECTION "..shared_aligned" | |
34 | #define PER_CPU_FIRST_SECTION "" | |
35 | ||
36 | #endif | |
37 | ||
5028eaa9 DH |
38 | /* |
39 | * Base implementations of per-CPU variable declarations and definitions, where | |
40 | * the section in which the variable is to be placed is provided by the | |
7c756e6e | 41 | * 'sec' argument. This may be used to affect the parameters governing the |
5028eaa9 DH |
42 | * variable's storage. |
43 | * | |
44 | * NOTE! The sections for the DECLARE and for the DEFINE must match, lest | |
45 | * linkage errors occur due the compiler generating the wrong code to access | |
46 | * that section. | |
47 | */ | |
7c756e6e | 48 | #define __PCPU_ATTRS(sec) \ |
e0fdb0e0 | 49 | __percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \ |
7c756e6e TH |
50 | PER_CPU_ATTRIBUTES |
51 | ||
52 | #define __PCPU_DUMMY_ATTRS \ | |
53 | __attribute__((section(".discard"), unused)) | |
54 | ||
545695fb TH |
55 | /* |
56 | * Macro which verifies @ptr is a percpu pointer without evaluating | |
57 | * @ptr. This is to be used in percpu accessors to verify that the | |
58 | * input parameter is a percpu pointer. | |
abec1a80 CL |
59 | * |
60 | * + 0 is required in order to convert the pointer type from a | |
61 | * potential array type to a pointer to a single item of the array. | |
545695fb TH |
62 | */ |
63 | #define __verify_pcpu_ptr(ptr) do { \ | |
abec1a80 | 64 | const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \ |
545695fb TH |
65 | (void)__vpp_verify; \ |
66 | } while (0) | |
67 | ||
7c756e6e TH |
68 | /* |
69 | * s390 and alpha modules require percpu variables to be defined as | |
70 | * weak to force the compiler to generate GOT based external | |
71 | * references for them. This is necessary because percpu sections | |
72 | * will be located outside of the usually addressable area. | |
73 | * | |
74 | * This definition puts the following two extra restrictions when | |
75 | * defining percpu variables. | |
76 | * | |
77 | * 1. The symbol must be globally unique, even the static ones. | |
78 | * 2. Static percpu variables cannot be defined inside a function. | |
79 | * | |
80 | * Archs which need weak percpu definitions should define | |
81 | * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary. | |
82 | * | |
83 | * To ensure that the generic code observes the above two | |
84 | * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak | |
85 | * definition is used for all cases. | |
86 | */ | |
87 | #if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU) | |
88 | /* | |
89 | * __pcpu_scope_* dummy variable is used to enforce scope. It | |
90 | * receives the static modifier when it's used in front of | |
91 | * DEFINE_PER_CPU() and will trigger build failure if | |
92 | * DECLARE_PER_CPU() is used for the same variable. | |
93 | * | |
94 | * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness | |
95 | * such that hidden weak symbol collision, which will cause unrelated | |
96 | * variables to share the same address, can be detected during build. | |
97 | */ | |
98 | #define DECLARE_PER_CPU_SECTION(type, name, sec) \ | |
99 | extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ | |
dd17c8f7 | 100 | extern __PCPU_ATTRS(sec) __typeof__(type) name |
7c756e6e TH |
101 | |
102 | #define DEFINE_PER_CPU_SECTION(type, name, sec) \ | |
103 | __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ | |
0f5e4816 | 104 | extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ |
7c756e6e | 105 | __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ |
b1a0fbfd | 106 | extern __PCPU_ATTRS(sec) __typeof__(type) name; \ |
c43768cb | 107 | __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \ |
dd17c8f7 | 108 | __typeof__(type) name |
7c756e6e TH |
109 | #else |
110 | /* | |
111 | * Normal declaration and definition macros. | |
112 | */ | |
113 | #define DECLARE_PER_CPU_SECTION(type, name, sec) \ | |
dd17c8f7 | 114 | extern __PCPU_ATTRS(sec) __typeof__(type) name |
7c756e6e TH |
115 | |
116 | #define DEFINE_PER_CPU_SECTION(type, name, sec) \ | |
c43768cb | 117 | __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \ |
dd17c8f7 | 118 | __typeof__(type) name |
7c756e6e | 119 | #endif |
5028eaa9 DH |
120 | |
121 | /* | |
122 | * Variant on the per-CPU variable declaration/definition theme used for | |
123 | * ordinary per-CPU variables. | |
124 | */ | |
125 | #define DECLARE_PER_CPU(type, name) \ | |
126 | DECLARE_PER_CPU_SECTION(type, name, "") | |
127 | ||
128 | #define DEFINE_PER_CPU(type, name) \ | |
129 | DEFINE_PER_CPU_SECTION(type, name, "") | |
130 | ||
131 | /* | |
132 | * Declaration/definition used for per-CPU variables that must come first in | |
133 | * the set of variables. | |
134 | */ | |
135 | #define DECLARE_PER_CPU_FIRST(type, name) \ | |
136 | DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION) | |
137 | ||
138 | #define DEFINE_PER_CPU_FIRST(type, name) \ | |
139 | DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION) | |
140 | ||
141 | /* | |
142 | * Declaration/definition used for per-CPU variables that must be cacheline | |
143 | * aligned under SMP conditions so that, whilst a particular instance of the | |
144 | * data corresponds to a particular CPU, inefficiencies due to direct access by | |
145 | * other CPUs are reduced by preventing the data from unnecessarily spanning | |
146 | * cachelines. | |
147 | * | |
148 | * An example of this would be statistical data, where each CPU's set of data | |
149 | * is updated by that CPU alone, but the data from across all CPUs is collated | |
150 | * by a CPU processing a read from a proc file. | |
151 | */ | |
152 | #define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \ | |
153 | DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \ | |
154 | ____cacheline_aligned_in_smp | |
155 | ||
156 | #define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \ | |
157 | DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \ | |
158 | ____cacheline_aligned_in_smp | |
159 | ||
53f82452 JF |
160 | #define DECLARE_PER_CPU_ALIGNED(type, name) \ |
161 | DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \ | |
162 | ____cacheline_aligned | |
163 | ||
164 | #define DEFINE_PER_CPU_ALIGNED(type, name) \ | |
165 | DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \ | |
166 | ____cacheline_aligned | |
167 | ||
5028eaa9 DH |
168 | /* |
169 | * Declaration/definition used for per-CPU variables that must be page aligned. | |
170 | */ | |
3e352aa8 | 171 | #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \ |
3d9a854c | 172 | DECLARE_PER_CPU_SECTION(type, name, "..page_aligned") \ |
3e352aa8 | 173 | __aligned(PAGE_SIZE) |
5028eaa9 DH |
174 | |
175 | #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \ | |
3d9a854c | 176 | DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \ |
3e352aa8 | 177 | __aligned(PAGE_SIZE) |
5028eaa9 | 178 | |
c957ef2c SL |
179 | /* |
180 | * Declaration/definition used for per-CPU variables that must be read mostly. | |
181 | */ | |
182 | #define DECLARE_PER_CPU_READ_MOSTLY(type, name) \ | |
183 | DECLARE_PER_CPU_SECTION(type, name, "..readmostly") | |
184 | ||
185 | #define DEFINE_PER_CPU_READ_MOSTLY(type, name) \ | |
186 | DEFINE_PER_CPU_SECTION(type, name, "..readmostly") | |
187 | ||
5028eaa9 | 188 | /* |
545695fb TH |
189 | * Intermodule exports for per-CPU variables. sparse forgets about |
190 | * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to | |
191 | * noop if __CHECKER__. | |
5028eaa9 | 192 | */ |
545695fb | 193 | #ifndef __CHECKER__ |
dd17c8f7 RR |
194 | #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var) |
195 | #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var) | |
545695fb TH |
196 | #else |
197 | #define EXPORT_PER_CPU_SYMBOL(var) | |
198 | #define EXPORT_PER_CPU_SYMBOL_GPL(var) | |
199 | #endif | |
5028eaa9 | 200 | |
62fde541 TH |
201 | /* |
202 | * Accessors and operations. | |
203 | */ | |
204 | #ifndef __ASSEMBLY__ | |
205 | ||
206 | #ifdef CONFIG_SMP | |
207 | ||
208 | /* | |
209 | * Add an offset to a pointer but keep the pointer as-is. Use RELOC_HIDE() | |
210 | * to prevent the compiler from making incorrect assumptions about the | |
211 | * pointer value. The weird cast keeps both GCC and sparse happy. | |
212 | */ | |
213 | #define SHIFT_PERCPU_PTR(__p, __offset) ({ \ | |
214 | __verify_pcpu_ptr((__p)); \ | |
215 | RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset)); \ | |
216 | }) | |
217 | ||
218 | /* | |
219 | * A percpu variable may point to a discarded regions. The following are | |
220 | * established ways to produce a usable pointer from the percpu variable | |
221 | * offset. | |
222 | */ | |
223 | #define per_cpu(var, cpu) \ | |
224 | (*SHIFT_PERCPU_PTR(&(var), per_cpu_offset(cpu))) | |
225 | ||
226 | #define raw_cpu_ptr(ptr) arch_raw_cpu_ptr(ptr) | |
227 | ||
228 | #ifdef CONFIG_DEBUG_PREEMPT | |
229 | #define this_cpu_ptr(ptr) SHIFT_PERCPU_PTR(ptr, my_cpu_offset) | |
230 | #else | |
231 | #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr) | |
232 | #endif | |
233 | ||
234 | #define __get_cpu_var(var) (*this_cpu_ptr(&(var))) | |
235 | #define __raw_get_cpu_var(var) (*raw_cpu_ptr(&(var))) | |
236 | ||
237 | #else /* CONFIG_SMP */ | |
238 | ||
239 | #define VERIFY_PERCPU_PTR(__p) ({ \ | |
240 | __verify_pcpu_ptr((__p)); \ | |
241 | (typeof(*(__p)) __kernel __force *)(__p); \ | |
242 | }) | |
243 | ||
244 | #define per_cpu(var, cpu) (*((void)(cpu), VERIFY_PERCPU_PTR(&(var)))) | |
245 | #define __get_cpu_var(var) (*VERIFY_PERCPU_PTR(&(var))) | |
246 | #define __raw_get_cpu_var(var) (*VERIFY_PERCPU_PTR(&(var))) | |
247 | #define this_cpu_ptr(ptr) per_cpu_ptr(ptr, 0) | |
248 | #define raw_cpu_ptr(ptr) this_cpu_ptr(ptr) | |
249 | ||
250 | #endif /* CONFIG_SMP */ | |
251 | ||
252 | /* keep until we have removed all uses of __this_cpu_ptr */ | |
253 | #define __this_cpu_ptr(ptr) raw_cpu_ptr(ptr) | |
254 | ||
255 | #endif /* __ASSEMBLY__ */ | |
5028eaa9 | 256 | #endif /* _LINUX_PERCPU_DEFS_H */ |