tracing: Add trace_seq_has_overflowed() and trace_handle_return()
[deliverable/linux.git] / include / linux / percpu-defs.h
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
16 #ifndef _LINUX_PERCPU_DEFS_H
17 #define _LINUX_PERCPU_DEFS_H
18
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
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
41 * 'sec' argument. This may be used to affect the parameters governing the
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 */
48 #define __PCPU_ATTRS(sec) \
49 __percpu __attribute__((section(PER_CPU_BASE_SECTION sec))) \
50 PER_CPU_ATTRIBUTES
51
52 #define __PCPU_DUMMY_ATTRS \
53 __attribute__((section(".discard"), unused))
54
55 /*
56 * s390 and alpha modules require percpu variables to be defined as
57 * weak to force the compiler to generate GOT based external
58 * references for them. This is necessary because percpu sections
59 * will be located outside of the usually addressable area.
60 *
61 * This definition puts the following two extra restrictions when
62 * defining percpu variables.
63 *
64 * 1. The symbol must be globally unique, even the static ones.
65 * 2. Static percpu variables cannot be defined inside a function.
66 *
67 * Archs which need weak percpu definitions should define
68 * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary.
69 *
70 * To ensure that the generic code observes the above two
71 * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak
72 * definition is used for all cases.
73 */
74 #if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU)
75 /*
76 * __pcpu_scope_* dummy variable is used to enforce scope. It
77 * receives the static modifier when it's used in front of
78 * DEFINE_PER_CPU() and will trigger build failure if
79 * DECLARE_PER_CPU() is used for the same variable.
80 *
81 * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness
82 * such that hidden weak symbol collision, which will cause unrelated
83 * variables to share the same address, can be detected during build.
84 */
85 #define DECLARE_PER_CPU_SECTION(type, name, sec) \
86 extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
87 extern __PCPU_ATTRS(sec) __typeof__(type) name
88
89 #define DEFINE_PER_CPU_SECTION(type, name, sec) \
90 __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
91 extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
92 __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
93 extern __PCPU_ATTRS(sec) __typeof__(type) name; \
94 __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \
95 __typeof__(type) name
96 #else
97 /*
98 * Normal declaration and definition macros.
99 */
100 #define DECLARE_PER_CPU_SECTION(type, name, sec) \
101 extern __PCPU_ATTRS(sec) __typeof__(type) name
102
103 #define DEFINE_PER_CPU_SECTION(type, name, sec) \
104 __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \
105 __typeof__(type) name
106 #endif
107
108 /*
109 * Variant on the per-CPU variable declaration/definition theme used for
110 * ordinary per-CPU variables.
111 */
112 #define DECLARE_PER_CPU(type, name) \
113 DECLARE_PER_CPU_SECTION(type, name, "")
114
115 #define DEFINE_PER_CPU(type, name) \
116 DEFINE_PER_CPU_SECTION(type, name, "")
117
118 /*
119 * Declaration/definition used for per-CPU variables that must come first in
120 * the set of variables.
121 */
122 #define DECLARE_PER_CPU_FIRST(type, name) \
123 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
124
125 #define DEFINE_PER_CPU_FIRST(type, name) \
126 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_FIRST_SECTION)
127
128 /*
129 * Declaration/definition used for per-CPU variables that must be cacheline
130 * aligned under SMP conditions so that, whilst a particular instance of the
131 * data corresponds to a particular CPU, inefficiencies due to direct access by
132 * other CPUs are reduced by preventing the data from unnecessarily spanning
133 * cachelines.
134 *
135 * An example of this would be statistical data, where each CPU's set of data
136 * is updated by that CPU alone, but the data from across all CPUs is collated
137 * by a CPU processing a read from a proc file.
138 */
139 #define DECLARE_PER_CPU_SHARED_ALIGNED(type, name) \
140 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
141 ____cacheline_aligned_in_smp
142
143 #define DEFINE_PER_CPU_SHARED_ALIGNED(type, name) \
144 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_SHARED_ALIGNED_SECTION) \
145 ____cacheline_aligned_in_smp
146
147 #define DECLARE_PER_CPU_ALIGNED(type, name) \
148 DECLARE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
149 ____cacheline_aligned
150
151 #define DEFINE_PER_CPU_ALIGNED(type, name) \
152 DEFINE_PER_CPU_SECTION(type, name, PER_CPU_ALIGNED_SECTION) \
153 ____cacheline_aligned
154
155 /*
156 * Declaration/definition used for per-CPU variables that must be page aligned.
157 */
158 #define DECLARE_PER_CPU_PAGE_ALIGNED(type, name) \
159 DECLARE_PER_CPU_SECTION(type, name, "..page_aligned") \
160 __aligned(PAGE_SIZE)
161
162 #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
163 DEFINE_PER_CPU_SECTION(type, name, "..page_aligned") \
164 __aligned(PAGE_SIZE)
165
166 /*
167 * Declaration/definition used for per-CPU variables that must be read mostly.
168 */
169 #define DECLARE_PER_CPU_READ_MOSTLY(type, name) \
170 DECLARE_PER_CPU_SECTION(type, name, "..read_mostly")
171
172 #define DEFINE_PER_CPU_READ_MOSTLY(type, name) \
173 DEFINE_PER_CPU_SECTION(type, name, "..read_mostly")
174
175 /*
176 * Intermodule exports for per-CPU variables. sparse forgets about
177 * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to
178 * noop if __CHECKER__.
179 */
180 #ifndef __CHECKER__
181 #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var)
182 #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var)
183 #else
184 #define EXPORT_PER_CPU_SYMBOL(var)
185 #define EXPORT_PER_CPU_SYMBOL_GPL(var)
186 #endif
187
188 /*
189 * Accessors and operations.
190 */
191 #ifndef __ASSEMBLY__
192
193 /*
194 * __verify_pcpu_ptr() verifies @ptr is a percpu pointer without evaluating
195 * @ptr and is invoked once before a percpu area is accessed by all
196 * accessors and operations. This is performed in the generic part of
197 * percpu and arch overrides don't need to worry about it; however, if an
198 * arch wants to implement an arch-specific percpu accessor or operation,
199 * it may use __verify_pcpu_ptr() to verify the parameters.
200 *
201 * + 0 is required in order to convert the pointer type from a
202 * potential array type to a pointer to a single item of the array.
203 */
204 #define __verify_pcpu_ptr(ptr) \
205 do { \
206 const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \
207 (void)__vpp_verify; \
208 } while (0)
209
210 #ifdef CONFIG_SMP
211
212 /*
213 * Add an offset to a pointer but keep the pointer as-is. Use RELOC_HIDE()
214 * to prevent the compiler from making incorrect assumptions about the
215 * pointer value. The weird cast keeps both GCC and sparse happy.
216 */
217 #define SHIFT_PERCPU_PTR(__p, __offset) \
218 RELOC_HIDE((typeof(*(__p)) __kernel __force *)(__p), (__offset))
219
220 #define per_cpu_ptr(ptr, cpu) \
221 ({ \
222 __verify_pcpu_ptr(ptr); \
223 SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))); \
224 })
225
226 #define raw_cpu_ptr(ptr) \
227 ({ \
228 __verify_pcpu_ptr(ptr); \
229 arch_raw_cpu_ptr(ptr); \
230 })
231
232 #ifdef CONFIG_DEBUG_PREEMPT
233 #define this_cpu_ptr(ptr) \
234 ({ \
235 __verify_pcpu_ptr(ptr); \
236 SHIFT_PERCPU_PTR(ptr, my_cpu_offset); \
237 })
238 #else
239 #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
240 #endif
241
242 #else /* CONFIG_SMP */
243
244 #define VERIFY_PERCPU_PTR(__p) \
245 ({ \
246 __verify_pcpu_ptr(__p); \
247 (typeof(*(__p)) __kernel __force *)(__p); \
248 })
249
250 #define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); VERIFY_PERCPU_PTR(ptr); })
251 #define raw_cpu_ptr(ptr) per_cpu_ptr(ptr, 0)
252 #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr)
253
254 #endif /* CONFIG_SMP */
255
256 #define per_cpu(var, cpu) (*per_cpu_ptr(&(var), cpu))
257 #define __raw_get_cpu_var(var) (*raw_cpu_ptr(&(var)))
258 #define __get_cpu_var(var) (*this_cpu_ptr(&(var)))
259
260 /*
261 * Must be an lvalue. Since @var must be a simple identifier,
262 * we force a syntax error here if it isn't.
263 */
264 #define get_cpu_var(var) \
265 (*({ \
266 preempt_disable(); \
267 this_cpu_ptr(&var); \
268 }))
269
270 /*
271 * The weird & is necessary because sparse considers (void)(var) to be
272 * a direct dereference of percpu variable (var).
273 */
274 #define put_cpu_var(var) \
275 do { \
276 (void)&(var); \
277 preempt_enable(); \
278 } while (0)
279
280 #define get_cpu_ptr(var) \
281 ({ \
282 preempt_disable(); \
283 this_cpu_ptr(var); \
284 })
285
286 #define put_cpu_ptr(var) \
287 do { \
288 (void)(var); \
289 preempt_enable(); \
290 } while (0)
291
292 /*
293 * Branching function to split up a function into a set of functions that
294 * are called for different scalar sizes of the objects handled.
295 */
296
297 extern void __bad_size_call_parameter(void);
298
299 #ifdef CONFIG_DEBUG_PREEMPT
300 extern void __this_cpu_preempt_check(const char *op);
301 #else
302 static inline void __this_cpu_preempt_check(const char *op) { }
303 #endif
304
305 #define __pcpu_size_call_return(stem, variable) \
306 ({ \
307 typeof(variable) pscr_ret__; \
308 __verify_pcpu_ptr(&(variable)); \
309 switch(sizeof(variable)) { \
310 case 1: pscr_ret__ = stem##1(variable); break; \
311 case 2: pscr_ret__ = stem##2(variable); break; \
312 case 4: pscr_ret__ = stem##4(variable); break; \
313 case 8: pscr_ret__ = stem##8(variable); break; \
314 default: \
315 __bad_size_call_parameter(); break; \
316 } \
317 pscr_ret__; \
318 })
319
320 #define __pcpu_size_call_return2(stem, variable, ...) \
321 ({ \
322 typeof(variable) pscr2_ret__; \
323 __verify_pcpu_ptr(&(variable)); \
324 switch(sizeof(variable)) { \
325 case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break; \
326 case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break; \
327 case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break; \
328 case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break; \
329 default: \
330 __bad_size_call_parameter(); break; \
331 } \
332 pscr2_ret__; \
333 })
334
335 /*
336 * Special handling for cmpxchg_double. cmpxchg_double is passed two
337 * percpu variables. The first has to be aligned to a double word
338 * boundary and the second has to follow directly thereafter.
339 * We enforce this on all architectures even if they don't support
340 * a double cmpxchg instruction, since it's a cheap requirement, and it
341 * avoids breaking the requirement for architectures with the instruction.
342 */
343 #define __pcpu_double_call_return_bool(stem, pcp1, pcp2, ...) \
344 ({ \
345 bool pdcrb_ret__; \
346 __verify_pcpu_ptr(&(pcp1)); \
347 BUILD_BUG_ON(sizeof(pcp1) != sizeof(pcp2)); \
348 VM_BUG_ON((unsigned long)(&(pcp1)) % (2 * sizeof(pcp1))); \
349 VM_BUG_ON((unsigned long)(&(pcp2)) != \
350 (unsigned long)(&(pcp1)) + sizeof(pcp1)); \
351 switch(sizeof(pcp1)) { \
352 case 1: pdcrb_ret__ = stem##1(pcp1, pcp2, __VA_ARGS__); break; \
353 case 2: pdcrb_ret__ = stem##2(pcp1, pcp2, __VA_ARGS__); break; \
354 case 4: pdcrb_ret__ = stem##4(pcp1, pcp2, __VA_ARGS__); break; \
355 case 8: pdcrb_ret__ = stem##8(pcp1, pcp2, __VA_ARGS__); break; \
356 default: \
357 __bad_size_call_parameter(); break; \
358 } \
359 pdcrb_ret__; \
360 })
361
362 #define __pcpu_size_call(stem, variable, ...) \
363 do { \
364 __verify_pcpu_ptr(&(variable)); \
365 switch(sizeof(variable)) { \
366 case 1: stem##1(variable, __VA_ARGS__);break; \
367 case 2: stem##2(variable, __VA_ARGS__);break; \
368 case 4: stem##4(variable, __VA_ARGS__);break; \
369 case 8: stem##8(variable, __VA_ARGS__);break; \
370 default: \
371 __bad_size_call_parameter();break; \
372 } \
373 } while (0)
374
375 /*
376 * this_cpu operations (C) 2008-2013 Christoph Lameter <cl@linux.com>
377 *
378 * Optimized manipulation for memory allocated through the per cpu
379 * allocator or for addresses of per cpu variables.
380 *
381 * These operation guarantee exclusivity of access for other operations
382 * on the *same* processor. The assumption is that per cpu data is only
383 * accessed by a single processor instance (the current one).
384 *
385 * The arch code can provide optimized implementation by defining macros
386 * for certain scalar sizes. F.e. provide this_cpu_add_2() to provide per
387 * cpu atomic operations for 2 byte sized RMW actions. If arch code does
388 * not provide operations for a scalar size then the fallback in the
389 * generic code will be used.
390 *
391 * cmpxchg_double replaces two adjacent scalars at once. The first two
392 * parameters are per cpu variables which have to be of the same size. A
393 * truth value is returned to indicate success or failure (since a double
394 * register result is difficult to handle). There is very limited hardware
395 * support for these operations, so only certain sizes may work.
396 */
397
398 /*
399 * Operations for contexts where we do not want to do any checks for
400 * preemptions. Unless strictly necessary, always use [__]this_cpu_*()
401 * instead.
402 *
403 * If there is no other protection through preempt disable and/or disabling
404 * interupts then one of these RMW operations can show unexpected behavior
405 * because the execution thread was rescheduled on another processor or an
406 * interrupt occurred and the same percpu variable was modified from the
407 * interrupt context.
408 */
409 #define raw_cpu_read(pcp) __pcpu_size_call_return(raw_cpu_read_, pcp)
410 #define raw_cpu_write(pcp, val) __pcpu_size_call(raw_cpu_write_, pcp, val)
411 #define raw_cpu_add(pcp, val) __pcpu_size_call(raw_cpu_add_, pcp, val)
412 #define raw_cpu_and(pcp, val) __pcpu_size_call(raw_cpu_and_, pcp, val)
413 #define raw_cpu_or(pcp, val) __pcpu_size_call(raw_cpu_or_, pcp, val)
414 #define raw_cpu_add_return(pcp, val) __pcpu_size_call_return2(raw_cpu_add_return_, pcp, val)
415 #define raw_cpu_xchg(pcp, nval) __pcpu_size_call_return2(raw_cpu_xchg_, pcp, nval)
416 #define raw_cpu_cmpxchg(pcp, oval, nval) \
417 __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval)
418 #define raw_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
419 __pcpu_double_call_return_bool(raw_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2)
420
421 #define raw_cpu_sub(pcp, val) raw_cpu_add(pcp, -(val))
422 #define raw_cpu_inc(pcp) raw_cpu_add(pcp, 1)
423 #define raw_cpu_dec(pcp) raw_cpu_sub(pcp, 1)
424 #define raw_cpu_sub_return(pcp, val) raw_cpu_add_return(pcp, -(typeof(pcp))(val))
425 #define raw_cpu_inc_return(pcp) raw_cpu_add_return(pcp, 1)
426 #define raw_cpu_dec_return(pcp) raw_cpu_add_return(pcp, -1)
427
428 /*
429 * Operations for contexts that are safe from preemption/interrupts. These
430 * operations verify that preemption is disabled.
431 */
432 #define __this_cpu_read(pcp) \
433 ({ \
434 __this_cpu_preempt_check("read"); \
435 raw_cpu_read(pcp); \
436 })
437
438 #define __this_cpu_write(pcp, val) \
439 ({ \
440 __this_cpu_preempt_check("write"); \
441 raw_cpu_write(pcp, val); \
442 })
443
444 #define __this_cpu_add(pcp, val) \
445 ({ \
446 __this_cpu_preempt_check("add"); \
447 raw_cpu_add(pcp, val); \
448 })
449
450 #define __this_cpu_and(pcp, val) \
451 ({ \
452 __this_cpu_preempt_check("and"); \
453 raw_cpu_and(pcp, val); \
454 })
455
456 #define __this_cpu_or(pcp, val) \
457 ({ \
458 __this_cpu_preempt_check("or"); \
459 raw_cpu_or(pcp, val); \
460 })
461
462 #define __this_cpu_add_return(pcp, val) \
463 ({ \
464 __this_cpu_preempt_check("add_return"); \
465 raw_cpu_add_return(pcp, val); \
466 })
467
468 #define __this_cpu_xchg(pcp, nval) \
469 ({ \
470 __this_cpu_preempt_check("xchg"); \
471 raw_cpu_xchg(pcp, nval); \
472 })
473
474 #define __this_cpu_cmpxchg(pcp, oval, nval) \
475 ({ \
476 __this_cpu_preempt_check("cmpxchg"); \
477 raw_cpu_cmpxchg(pcp, oval, nval); \
478 })
479
480 #define __this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
481 ({ __this_cpu_preempt_check("cmpxchg_double"); \
482 raw_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2); \
483 })
484
485 #define __this_cpu_sub(pcp, val) __this_cpu_add(pcp, -(typeof(pcp))(val))
486 #define __this_cpu_inc(pcp) __this_cpu_add(pcp, 1)
487 #define __this_cpu_dec(pcp) __this_cpu_sub(pcp, 1)
488 #define __this_cpu_sub_return(pcp, val) __this_cpu_add_return(pcp, -(typeof(pcp))(val))
489 #define __this_cpu_inc_return(pcp) __this_cpu_add_return(pcp, 1)
490 #define __this_cpu_dec_return(pcp) __this_cpu_add_return(pcp, -1)
491
492 /*
493 * Operations with implied preemption protection. These operations can be
494 * used without worrying about preemption. Note that interrupts may still
495 * occur while an operation is in progress and if the interrupt modifies
496 * the variable too then RMW actions may not be reliable.
497 */
498 #define this_cpu_read(pcp) __pcpu_size_call_return(this_cpu_read_, pcp)
499 #define this_cpu_write(pcp, val) __pcpu_size_call(this_cpu_write_, pcp, val)
500 #define this_cpu_add(pcp, val) __pcpu_size_call(this_cpu_add_, pcp, val)
501 #define this_cpu_and(pcp, val) __pcpu_size_call(this_cpu_and_, pcp, val)
502 #define this_cpu_or(pcp, val) __pcpu_size_call(this_cpu_or_, pcp, val)
503 #define this_cpu_add_return(pcp, val) __pcpu_size_call_return2(this_cpu_add_return_, pcp, val)
504 #define this_cpu_xchg(pcp, nval) __pcpu_size_call_return2(this_cpu_xchg_, pcp, nval)
505 #define this_cpu_cmpxchg(pcp, oval, nval) \
506 __pcpu_size_call_return2(this_cpu_cmpxchg_, pcp, oval, nval)
507 #define this_cpu_cmpxchg_double(pcp1, pcp2, oval1, oval2, nval1, nval2) \
508 __pcpu_double_call_return_bool(this_cpu_cmpxchg_double_, pcp1, pcp2, oval1, oval2, nval1, nval2)
509
510 #define this_cpu_sub(pcp, val) this_cpu_add(pcp, -(typeof(pcp))(val))
511 #define this_cpu_inc(pcp) this_cpu_add(pcp, 1)
512 #define this_cpu_dec(pcp) this_cpu_sub(pcp, 1)
513 #define this_cpu_sub_return(pcp, val) this_cpu_add_return(pcp, -(typeof(pcp))(val))
514 #define this_cpu_inc_return(pcp) this_cpu_add_return(pcp, 1)
515 #define this_cpu_dec_return(pcp) this_cpu_add_return(pcp, -1)
516
517 #endif /* __ASSEMBLY__ */
518 #endif /* _LINUX_PERCPU_DEFS_H */
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