1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * linux/percpu-defs.h - basic definitions for percpu areas
4 *
5 * DO NOT INCLUDE DIRECTLY OUTSIDE PERCPU IMPLEMENTATION PROPER.
6 *
7 * This file is separate from linux/percpu.h to avoid cyclic inclusion
8 * dependency from arch header files. Only to be included from
9 * asm/percpu.h.
10 *
11 * This file includes macros necessary to declare percpu sections and
12 * variables, and definitions of percpu accessors and operations. It
13 * should provide enough percpu features to arch header files even when
14 * they can only include asm/percpu.h to avoid cyclic inclusion dependency.
15 */
16
17 #ifndef _LINUX_PERCPU_DEFS_H
18 #define _LINUX_PERCPU_DEFS_H
19
20 #ifdef CONFIG_SMP
21
22 #ifdef MODULE
23 #define PER_CPU_SHARED_ALIGNED_SECTION ""
24 #define PER_CPU_ALIGNED_SECTION ""
25 #else
26 #define PER_CPU_SHARED_ALIGNED_SECTION "..shared_aligned"
27 #define PER_CPU_ALIGNED_SECTION "..shared_aligned"
28 #endif
29
30 #else
31
32 #define PER_CPU_SHARED_ALIGNED_SECTION ""
33 #define PER_CPU_ALIGNED_SECTION "..shared_aligned"
34
35 #endif
36
37 /*
38 * Base implementations of per-CPU variable declarations and definitions, where
39 * the section in which the variable is to be placed is provided by the
40 * 'sec' argument. This may be used to affect the parameters governing the
41 * variable's storage.
42 *
43 * NOTE! The sections for the DECLARE and for the DEFINE must match, lest
44 * linkage errors occur due the compiler generating the wrong code to access
45 * that section.
46 */
47 #define __PCPU_ATTRS(sec) \
48 __percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \
49 PER_CPU_ATTRIBUTES
50
51 #define __PCPU_DUMMY_ATTRS \
52 __section(".discard") __attribute__((unused))
53
54 /*
55 * alpha modules require percpu variables to be defined as
56 * weak to force the compiler to generate GOT based external
57 * references for them. This is necessary because percpu sections
58 * will be located outside of the usually addressable area.
59 *
60 * This definition puts the following two extra restrictions when
61 * defining percpu variables.
62 *
63 * 1. The symbol must be globally unique, even the static ones.
64 * 2. Static percpu variables cannot be defined inside a function.
65 *
66 * Archs which need weak percpu definitions should set
67 * CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU when necessary.
68 */
69 #if defined(CONFIG_ARCH_MODULE_NEEDS_WEAK_PER_CPU) && defined(MODULE)
70 /*
71 * __pcpu_scope_* dummy variable is used to enforce scope. It
72 * receives the static modifier when it's used in front of
73 * DEFINE_PER_CPU() and will trigger build failure if
74 * DECLARE_PER_CPU() is used for the same variable.
75 *
76 * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness
77 * such that hidden weak symbol collision, which will cause unrelated
78 * variables to share the same address, can be detected during build.
79 */
80 #define DECLARE_PER_CPU_SECTION(type, name, sec) \
81 extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
82 extern __PCPU_ATTRS(sec) __typeof__(type) name
83
84 #define DEFINE_PER_CPU_SECTION(type, name, sec) \
85 __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
86 extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
87 __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
88 extern __PCPU_ATTRS(sec) __typeof__(type) name; \
89 __PCPU_ATTRS(sec) __weak __typeof__(type) name
90 #else
91 /*
92 * Normal declaration and definition macros.
93 */
94 #define DECLARE_PER_CPU_SECTION(type, name, sec) \
95 extern __PCPU_ATTRS(sec) __typeof__(type) name
96
97 #define DEFINE_PER_CPU_SECTION(type, name, sec) \
98 __PCPU_ATTRS(sec) __typeof__(type) name
99 #endif
100
101 /*
102 * Variant on the per-CPU variable declaration/definition theme used for
103 * ordinary per-CPU variables.
104 */
105 #define DECLARE_PER_CPU(type, name) \
106 DECLARE_PER_CPU_SECTION(type, name, "")
107
108 #define DEFINE_PER_CPU(type, name) \
109 DEFINE_PER_CPU_SECTION(type, name, "")
110
111 /*
112 * Declaration/definition used for per-CPU variables that are frequently
113 * accessed and should be in a single cacheline.
114 *
115 * For use only by architecture and core code. Only use scalar or pointer
116 * types to maximize density.
117 */
118 #define DECLARE_PER_CPU_CACHE_HOT(type, name) \
119 DECLARE_PER_CPU_SECTION(type, name, "..hot.." #name)
120
121 #define DEFINE_PER_CPU_CACHE_HOT(type, name) \
122 DEFINE_PER_CPU_SECTION(type, name, "..hot.." #name)
123
124 /*
125 * Declaration/definition used for per-CPU variables that must be cacheline
126 * aligned under SMP conditions so that, whilst a particular instance of the
127 * data corresponds to a particular CPU, inefficiencies due to direct access by
128 * other CPUs are reduced by preventing the data from unnecessarily spanning
129 * cachelines.
130 *
131 * An example of this would be statistical data, where each CPU's set of data
132 * is updated by that CPU alone, but the data from across all CPUs is collated
133 * by a CPU processing a read from a proc file.
134 */
135 #define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \
136 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
137 ____cacheline_aligned_in_smp
138
139 #define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
140 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
141 ____cacheline_aligned_in_smp
142
143 #define DECLARE_PER_CPU_ALIGNED(type, name) \
144 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
145 ____cacheline_aligned
146
147 #define DEFINE_PER_CPU_ALIGNED(type, name) \
148 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
149 ____cacheline_aligned
150
151 /*
152 * Declaration/definition used for per-CPU variables that must be page aligned.
153 */
154 #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \
155 DECLARE_PER_CPU_SECTION(type, name, "..page_aligned") \
156 __aligned(PAGE_SIZE)
157
158 #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
159 DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \
160 __aligned(PAGE_SIZE)
161
162 /*
163 * Declaration/definition used for per-CPU variables that must be read mostly.
164 */
165 #define DECLARE_PER_CPU_READ_MOSTLY(type, name) \
166 DECLARE_PER_CPU_SECTION(type, name, "..read_mostly")
167
168 #define DEFINE_PER_CPU_READ_MOSTLY(type, name) \
169 DEFINE_PER_CPU_SECTION(type, name, "..read_mostly")
170
171 /*
172 * Declaration/definition used for per-CPU variables that should be accessed
173 * as decrypted when memory encryption is enabled in the guest.
174 */
175 #ifdef CONFIG_AMD_MEM_ENCRYPT
176 #define DECLARE_PER_CPU_DECRYPTED(type, name) \
177 DECLARE_PER_CPU_SECTION(type, name, "..decrypted")
178
179 #define DEFINE_PER_CPU_DECRYPTED(type, name) \
180 DEFINE_PER_CPU_SECTION(type, name, "..decrypted")
181 #else
182 #define DEFINE_PER_CPU_DECRYPTED(type, name) DEFINE_PER_CPU(type, name)
183 #endif
184
185 /*
186 * Intermodule exports for per-CPU variables. sparse forgets about
187 * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to
188 * noop if __CHECKER__.
189 */
190 #ifndef __CHECKER__
191 #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var)
192 #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var)
193 #else
194 #define EXPORT_PER_CPU_SYMBOL(var)
195 #define EXPORT_PER_CPU_SYMBOL_GPL(var)
196 #endif
197
198 /*
199 * Accessors and operations.
200 */
201 #ifndef __ASSEMBLER__
202
203 /*
204 * __verify_pcpu_ptr() verifies @ptr is a percpu pointer without evaluating
205 * @ptr and is invoked once before a percpu area is accessed by all
206 * accessors and operations. This is performed in the generic part of
207 * percpu and arch overrides don't need to worry about it; however, if an
208 * arch wants to implement an arch-specific percpu accessor or operation,
209 * it may use __verify_pcpu_ptr() to verify the parameters.
210 *
211 * + 0 is required in order to convert the pointer type from a
212 * potential array type to a pointer to a single item of the array.
213 */
214 #define __verify_pcpu_ptr(ptr) \
215 do { \
216 const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \
217 (void)__vpp_verify; \
218 } while (0)
219
220 #define PERCPU_PTR(__p) \
221 (TYPEOF_UNQUAL(*(__p)) __force __kernel *)((__force unsigned long)(__p))
222
223 #ifdef CONFIG_SMP
224
225 /*
226 * Add an offset to a pointer. Use RELOC_HIDE() to prevent the compiler
227 * from making incorrect assumptions about the pointer value.
228 */
229 #define SHIFT_PERCPU_PTR(__p, __offset) \
230 RELOC_HIDE(PERCPU_PTR(__p), (__offset))
231
232 #define per_cpu_ptr(ptr, cpu) \
233 ({ \
234 __verify_pcpu_ptr(ptr); \
235 SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))); \
236 })
237
238 #define raw_cpu_ptr(ptr) \
239 ({ \
240 __verify_pcpu_ptr(ptr); \
241 arch_raw_cpu_ptr(ptr); \
242 })
243
244 #ifdef CONFIG_DEBUG_PREEMPT
245 #define this_cpu_ptr(ptr) \
246 ({ \
247 __verify_pcpu_ptr(ptr); \
248 SHIFT_PERCPU_PTR(ptr, my_cpu_offset); \
249 })
250 #else
251 #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
252 #endif
253
254 #else /* CONFIG_SMP */
255
256 #define per_cpu_ptr(ptr, cpu) \
257 ({ \
258 (void)(cpu); \
259 __verify_pcpu_ptr(ptr); \
260 PERCPU_PTR(ptr); \
261 })
262
263 #define raw_cpu_ptr(ptr) per_cpu_ptr(ptr, 0)
264 #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
265
266 #endif /* CONFIG_SMP */
267
268 #define per_cpu(var, cpu) (*per_cpu_ptr(&(var), cpu))
269
270 /*
271 * Must be an lvalue. Since @var must be a simple identifier,
272 * we force a syntax error here if it isn't.
273 */
274 #define get_cpu_var(var) \
275 (*({ \
276 preempt_disable(); \
277 this_cpu_ptr(&var); \
278 }))
279
280 /*
281 * The weird & is necessary because sparse considers (void)(var) to be
282 * a direct dereference of percpu variable (var).
283 */
284 #define put_cpu_var(var) \
285 do { \
286 (void)&(var); \
287 preempt_enable(); \
288 } while (0)
289
290 #define get_cpu_ptr(var) \
291 ({ \
292 preempt_disable(); \
293 this_cpu_ptr(var); \
294 })
295
296 #define put_cpu_ptr(var) \
297 do { \
298 (void)(var); \
299 preempt_enable(); \
300 } while (0)
301
302 /*
303 * Branching function to split up a function into a set of functions that
304 * are called for different scalar sizes of the objects handled.
305 */
306
307 extern void __bad_size_call_parameter(void);
308
309 #ifdef CONFIG_DEBUG_PREEMPT
310 extern void __this_cpu_preempt_check(const char *op);
311 #else
__this_cpu_preempt_check(const char * op)312 static __always_inline void __this_cpu_preempt_check(const char *op) { }
313 #endif
314
315 #define __pcpu_size_call_return(stem, variable) \
316 ({ \
317 TYPEOF_UNQUAL(variable) pscr_ret__; \
318 __verify_pcpu_ptr(&(variable)); \
319 switch(sizeof(variable)) { \
320 case 1: pscr_ret__ = stem##1(variable); break; \
321 case 2: pscr_ret__ = stem##2(variable); break; \
322 case 4: pscr_ret__ = stem##4(variable); break; \
323 case 8: pscr_ret__ = stem##8(variable); break; \
324 default: \
325 __bad_size_call_parameter(); break; \
326 } \
327 pscr_ret__; \
328 })
329
330 #define __pcpu_size_call_return2(stem, variable, ...) \
331 ({ \
332 TYPEOF_UNQUAL(variable) pscr2_ret__; \
333 __verify_pcpu_ptr(&(variable)); \
334 switch(sizeof(variable)) { \
335 case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break; \
336 case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break; \
337 case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break; \
338 case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break; \
339 default: \
340 __bad_size_call_parameter(); break; \
341 } \
342 pscr2_ret__; \
343 })
344
345 #define __pcpu_size_call_return2bool(stem, variable, ...) \
346 ({ \
347 bool pscr2_ret__; \
348 __verify_pcpu_ptr(&(variable)); \
349 switch(sizeof(variable)) { \
350 case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break; \
351 case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break; \
352 case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break; \
353 case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break; \
354 default: \
355 __bad_size_call_parameter(); break; \
356 } \
357 pscr2_ret__; \
358 })
359
360 #define __pcpu_size_call(stem, variable, ...) \
361 do { \
362 __verify_pcpu_ptr(&(variable)); \
363 switch(sizeof(variable)) { \
364 case 1: stem##1(variable, __VA_ARGS__);break; \
365 case 2: stem##2(variable, __VA_ARGS__);break; \
366 case 4: stem##4(variable, __VA_ARGS__);break; \
367 case 8: stem##8(variable, __VA_ARGS__);break; \
368 default: \
369 __bad_size_call_parameter();break; \
370 } \
371 } while (0)
372
373 /*
374 * this_cpu operations (C) 2008-2013 Christoph Lameter <cl@gentwo.org>
375 *
376 * Optimized manipulation for memory allocated through the per cpu
377 * allocator or for addresses of per cpu variables.
378 *
379 * These operation guarantee exclusivity of access for other operations
380 * on the *same* processor. The assumption is that per cpu data is only
381 * accessed by a single processor instance (the current one).
382 *
383 * The arch code can provide optimized implementation by defining macros
384 * for certain scalar sizes. F.e. provide this_cpu_add_2() to provide per
385 * cpu atomic operations for 2 byte sized RMW actions. If arch code does
386 * not provide operations for a scalar size then the fallback in the
387 * generic code will be used.
388 *
389 * cmpxchg_double replaces two adjacent scalars at once. The first two
390 * parameters are per cpu variables which have to be of the same size. A
391 * truth value is returned to indicate success or failure (since a double
392 * register result is difficult to handle). There is very limited hardware
393 * support for these operations, so only certain sizes may work.
394 */
395
396 /*
397 * Operations for contexts where we do not want to do any checks for
398 * preemptions. Unless strictly necessary, always use [__]this_cpu_*()
399 * instead.
400 *
401 * If there is no other protection through preempt disable and/or disabling
402 * interrupts then one of these RMW operations can show unexpected behavior
403 * because the execution thread was rescheduled on another processor or an
404 * interrupt occurred and the same percpu variable was modified from the
405 * interrupt context.
406 */
407 #define raw_cpu_read(pcp) __pcpu_size_call_return(raw_cpu_read_, pcp)
408 #define raw_cpu_write(pcp, val) __pcpu_size_call(raw_cpu_write_, pcp, val)
409 #define raw_cpu_add(pcp, val) __pcpu_size_call(raw_cpu_add_, pcp, val)
410 #define raw_cpu_and(pcp, val) __pcpu_size_call(raw_cpu_and_, pcp, val)
411 #define raw_cpu_or(pcp, val) __pcpu_size_call(raw_cpu_or_, pcp, val)
412 #define raw_cpu_add_return(pcp, val) __pcpu_size_call_return2(raw_cpu_add_return_, pcp, val)
413 #define raw_cpu_xchg(pcp, nval) __pcpu_size_call_return2(raw_cpu_xchg_, pcp, nval)
414 #define raw_cpu_cmpxchg(pcp, oval, nval) \
415 __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
416 #define raw_cpu_try_cmpxchg(pcp, ovalp, nval) \
417 __pcpu_size_call_return2bool(raw_cpu_try_cmpxchg_, pcp, ovalp, nval)
418 #define raw_cpu_sub(pcp, val) raw_cpu_add(pcp, -(val))
419 #define raw_cpu_inc(pcp) raw_cpu_add(pcp, 1)
420 #define raw_cpu_dec(pcp) raw_cpu_sub(pcp, 1)
421 #define raw_cpu_sub_return(pcp, val) raw_cpu_add_return(pcp, -(typeof(pcp))(val))
422 #define raw_cpu_inc_return(pcp) raw_cpu_add_return(pcp, 1)
423 #define raw_cpu_dec_return(pcp) raw_cpu_add_return(pcp, -1)
424
425 /*
426 * Operations for contexts that are safe from preemption/interrupts. These
427 * operations verify that preemption is disabled.
428 */
429 #define __this_cpu_read(pcp) \
430 ({ \
431 __this_cpu_preempt_check("read"); \
432 raw_cpu_read(pcp); \
433 })
434
435 #define __this_cpu_write(pcp, val) \
436 ({ \
437 __this_cpu_preempt_check("write"); \
438 raw_cpu_write(pcp, val); \
439 })
440
441 #define __this_cpu_add(pcp, val) \
442 ({ \
443 __this_cpu_preempt_check("add"); \
444 raw_cpu_add(pcp, val); \
445 })
446
447 #define __this_cpu_and(pcp, val) \
448 ({ \
449 __this_cpu_preempt_check("and"); \
450 raw_cpu_and(pcp, val); \
451 })
452
453 #define __this_cpu_or(pcp, val) \
454 ({ \
455 __this_cpu_preempt_check("or"); \
456 raw_cpu_or(pcp, val); \
457 })
458
459 #define __this_cpu_add_return(pcp, val) \
460 ({ \
461 __this_cpu_preempt_check("add_return"); \
462 raw_cpu_add_return(pcp, val); \
463 })
464
465 #define __this_cpu_xchg(pcp, nval) \
466 ({ \
467 __this_cpu_preempt_check("xchg"); \
468 raw_cpu_xchg(pcp, nval); \
469 })
470
471 #define __this_cpu_cmpxchg(pcp, oval, nval) \
472 ({ \
473 __this_cpu_preempt_check("cmpxchg"); \
474 raw_cpu_cmpxchg(pcp, oval, nval); \
475 })
476
477 #define __this_cpu_try_cmpxchg(pcp, ovalp, nval) \
478 ({ \
479 __this_cpu_preempt_check("try_cmpxchg"); \
480 raw_cpu_try_cmpxchg(pcp, ovalp, nval); \
481 })
482
483 #define __this_cpu_sub(pcp, val) __this_cpu_add(pcp, -(typeof(pcp))(val))
484 #define __this_cpu_inc(pcp) __this_cpu_add(pcp, 1)
485 #define __this_cpu_dec(pcp) __this_cpu_sub(pcp, 1)
486 #define __this_cpu_sub_return(pcp, val) __this_cpu_add_return(pcp, -(typeof(pcp))(val))
487 #define __this_cpu_inc_return(pcp) __this_cpu_add_return(pcp, 1)
488 #define __this_cpu_dec_return(pcp) __this_cpu_add_return(pcp, -1)
489
490 /*
491 * Operations with implied preemption/interrupt protection. These
492 * operations can be used without worrying about preemption or interrupt.
493 */
494 #define this_cpu_read(pcp) __pcpu_size_call_return(this_cpu_read_, pcp)
495 #define this_cpu_write(pcp, val) __pcpu_size_call(this_cpu_write_, pcp, val)
496 #define this_cpu_add(pcp, val) __pcpu_size_call(this_cpu_add_, pcp, val)
497 #define this_cpu_and(pcp, val) __pcpu_size_call(this_cpu_and_, pcp, val)
498 #define this_cpu_or(pcp, val) __pcpu_size_call(this_cpu_or_, pcp, val)
499 #define this_cpu_add_return(pcp, val) __pcpu_size_call_return2(this_cpu_add_return_, pcp, val)
500 #define this_cpu_xchg(pcp, nval) __pcpu_size_call_return2(this_cpu_xchg_, pcp, nval)
501 #define this_cpu_cmpxchg(pcp, oval, nval) \
502 __pcpu_size_call_return2(this_cpu_cmpxchg_, pcp, oval, nval)
503 #define this_cpu_try_cmpxchg(pcp, ovalp, nval) \
504 __pcpu_size_call_return2bool(this_cpu_try_cmpxchg_, pcp, ovalp, nval)
505 #define this_cpu_sub(pcp, val) this_cpu_add(pcp, -(typeof(pcp))(val))
506 #define this_cpu_inc(pcp) this_cpu_add(pcp, 1)
507 #define this_cpu_dec(pcp) this_cpu_sub(pcp, 1)
508 #define this_cpu_sub_return(pcp, val) this_cpu_add_return(pcp, -(typeof(pcp))(val))
509 #define this_cpu_inc_return(pcp) this_cpu_add_return(pcp, 1)
510 #define this_cpu_dec_return(pcp) this_cpu_add_return(pcp, -1)
511
512 #endif /* __ASSEMBLER__ */
513 #endif /* _LINUX_PERCPU_DEFS_H */
514