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 * s390 and 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 define 67 * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary. 68 * 69 * To ensure that the generic code observes the above two 70 * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak 71 * definition is used for all cases. 72 */ 73 #if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU) 74 /* 75 * __pcpu_scope_* dummy variable is used to enforce scope. It 76 * receives the static modifier when it's used in front of 77 * DEFINE_PER_CPU() and will trigger build failure if 78 * DECLARE_PER_CPU() is used for the same variable. 79 * 80 * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness 81 * such that hidden weak symbol collision, which will cause unrelated 82 * variables to share the same address, can be detected during build. 83 */ 84 #define DECLARE_PER_CPU_SECTION(type, name, sec) \ 85 extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ 86 extern __PCPU_ATTRS(sec) __typeof__(type) name 87 88 #define DEFINE_PER_CPU_SECTION(type, name, sec) \ 89 __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \ 90 extern __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ 91 __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \ 92 extern __PCPU_ATTRS(sec) __typeof__(type) name; \ 93 __PCPU_ATTRS(sec) __weak __typeof__(type) name 94 #else 95 /* 96 * Normal declaration and definition macros. 97 */ 98 #define DECLARE_PER_CPU_SECTION(type, name, sec) \ 99 extern __PCPU_ATTRS(sec) __typeof__(type) name 100 101 #define DEFINE_PER_CPU_SECTION(type, name, sec) \ 102 __PCPU_ATTRS(sec) __typeof__(type) name 103 #endif 104 105 /* 106 * Variant on the per-CPU variable declaration/definition theme used for 107 * ordinary per-CPU variables. 108 */ 109 #define DECLARE_PER_CPU(type, name) \ 110 DECLARE_PER_CPU_SECTION(type, name, "") 111 112 #define DEFINE_PER_CPU(type, name) \ 113 DEFINE_PER_CPU_SECTION(type, name, "") 114 115 /* 116 * Declaration/definition used for per-CPU variables that are frequently 117 * accessed and should be in a single cacheline. 118 * 119 * For use only by architecture and core code. Only use scalar or pointer 120 * types to maximize density. 121 */ 122 #define DECLARE_PER_CPU_CACHE_HOT(type, name) \ 123 DECLARE_PER_CPU_SECTION(type, name, "..hot.." #name) 124 125 #define DEFINE_PER_CPU_CACHE_HOT(type, name) \ 126 DEFINE_PER_CPU_SECTION(type, name, "..hot.." #name) 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 * Declaration/definition used for per-CPU variables that should be accessed 177 * as decrypted when memory encryption is enabled in the guest. 178 */ 179 #ifdef CONFIG_AMD_MEM_ENCRYPT 180 #define DECLARE_PER_CPU_DECRYPTED(type, name) \ 181 DECLARE_PER_CPU_SECTION(type, name, "..decrypted") 182 183 #define DEFINE_PER_CPU_DECRYPTED(type, name) \ 184 DEFINE_PER_CPU_SECTION(type, name, "..decrypted") 185 #else 186 #define DEFINE_PER_CPU_DECRYPTED(type, name) DEFINE_PER_CPU(type, name) 187 #endif 188 189 /* 190 * Intermodule exports for per-CPU variables. sparse forgets about 191 * address space across EXPORT_SYMBOL(), change EXPORT_SYMBOL() to 192 * noop if __CHECKER__. 193 */ 194 #ifndef __CHECKER__ 195 #define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(var) 196 #define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(var) 197 #else 198 #define EXPORT_PER_CPU_SYMBOL(var) 199 #define EXPORT_PER_CPU_SYMBOL_GPL(var) 200 #endif 201 202 /* 203 * Accessors and operations. 204 */ 205 #ifndef __ASSEMBLY__ 206 207 /* 208 * __verify_pcpu_ptr() verifies @ptr is a percpu pointer without evaluating 209 * @ptr and is invoked once before a percpu area is accessed by all 210 * accessors and operations. This is performed in the generic part of 211 * percpu and arch overrides don't need to worry about it; however, if an 212 * arch wants to implement an arch-specific percpu accessor or operation, 213 * it may use __verify_pcpu_ptr() to verify the parameters. 214 * 215 * + 0 is required in order to convert the pointer type from a 216 * potential array type to a pointer to a single item of the array. 217 */ 218 #define __verify_pcpu_ptr(ptr) \ 219 do { \ 220 const void __percpu *__vpp_verify = (typeof((ptr) + 0))NULL; \ 221 (void)__vpp_verify; \ 222 } while (0) 223 224 #define PERCPU_PTR(__p) \ 225 (TYPEOF_UNQUAL(*(__p)) __force __kernel *)((__force unsigned long)(__p)) 226 227 #ifdef CONFIG_SMP 228 229 /* 230 * Add an offset to a pointer. Use RELOC_HIDE() to prevent the compiler 231 * from making incorrect assumptions about the pointer value. 232 */ 233 #define SHIFT_PERCPU_PTR(__p, __offset) \ 234 RELOC_HIDE(PERCPU_PTR(__p), (__offset)) 235 236 #define per_cpu_ptr(ptr, cpu) \ 237 ({ \ 238 __verify_pcpu_ptr(ptr); \ 239 SHIFT_PERCPU_PTR((ptr), per_cpu_offset((cpu))); \ 240 }) 241 242 #define raw_cpu_ptr(ptr) \ 243 ({ \ 244 __verify_pcpu_ptr(ptr); \ 245 arch_raw_cpu_ptr(ptr); \ 246 }) 247 248 #ifdef CONFIG_DEBUG_PREEMPT 249 #define this_cpu_ptr(ptr) \ 250 ({ \ 251 __verify_pcpu_ptr(ptr); \ 252 SHIFT_PERCPU_PTR(ptr, my_cpu_offset); \ 253 }) 254 #else 255 #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr) 256 #endif 257 258 #else /* CONFIG_SMP */ 259 260 #define per_cpu_ptr(ptr, cpu) \ 261 ({ \ 262 (void)(cpu); \ 263 __verify_pcpu_ptr(ptr); \ 264 PERCPU_PTR(ptr); \ 265 }) 266 267 #define raw_cpu_ptr(ptr) per_cpu_ptr(ptr, 0) 268 #define this_cpu_ptr(ptr) raw_cpu_ptr(ptr) 269 270 #endif /* CONFIG_SMP */ 271 272 #define per_cpu(var, cpu) (*per_cpu_ptr(&(var), cpu)) 273 274 /* 275 * Must be an lvalue. Since @var must be a simple identifier, 276 * we force a syntax error here if it isn't. 277 */ 278 #define get_cpu_var(var) \ 279 (*({ \ 280 preempt_disable(); \ 281 this_cpu_ptr(&var); \ 282 })) 283 284 /* 285 * The weird & is necessary because sparse considers (void)(var) to be 286 * a direct dereference of percpu variable (var). 287 */ 288 #define put_cpu_var(var) \ 289 do { \ 290 (void)&(var); \ 291 preempt_enable(); \ 292 } while (0) 293 294 #define get_cpu_ptr(var) \ 295 ({ \ 296 preempt_disable(); \ 297 this_cpu_ptr(var); \ 298 }) 299 300 #define put_cpu_ptr(var) \ 301 do { \ 302 (void)(var); \ 303 preempt_enable(); \ 304 } while (0) 305 306 /* 307 * Branching function to split up a function into a set of functions that 308 * are called for different scalar sizes of the objects handled. 309 */ 310 311 extern void __bad_size_call_parameter(void); 312 313 #ifdef CONFIG_DEBUG_PREEMPT 314 extern void __this_cpu_preempt_check(const char *op); 315 #else 316 static __always_inline void __this_cpu_preempt_check(const char *op) { } 317 #endif 318 319 #define __pcpu_size_call_return(stem, variable) \ 320 ({ \ 321 TYPEOF_UNQUAL(variable) pscr_ret__; \ 322 __verify_pcpu_ptr(&(variable)); \ 323 switch(sizeof(variable)) { \ 324 case 1: pscr_ret__ = stem##1(variable); break; \ 325 case 2: pscr_ret__ = stem##2(variable); break; \ 326 case 4: pscr_ret__ = stem##4(variable); break; \ 327 case 8: pscr_ret__ = stem##8(variable); break; \ 328 default: \ 329 __bad_size_call_parameter(); break; \ 330 } \ 331 pscr_ret__; \ 332 }) 333 334 #define __pcpu_size_call_return2(stem, variable, ...) \ 335 ({ \ 336 TYPEOF_UNQUAL(variable) pscr2_ret__; \ 337 __verify_pcpu_ptr(&(variable)); \ 338 switch(sizeof(variable)) { \ 339 case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break; \ 340 case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break; \ 341 case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break; \ 342 case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break; \ 343 default: \ 344 __bad_size_call_parameter(); break; \ 345 } \ 346 pscr2_ret__; \ 347 }) 348 349 #define __pcpu_size_call_return2bool(stem, variable, ...) \ 350 ({ \ 351 bool pscr2_ret__; \ 352 __verify_pcpu_ptr(&(variable)); \ 353 switch(sizeof(variable)) { \ 354 case 1: pscr2_ret__ = stem##1(variable, __VA_ARGS__); break; \ 355 case 2: pscr2_ret__ = stem##2(variable, __VA_ARGS__); break; \ 356 case 4: pscr2_ret__ = stem##4(variable, __VA_ARGS__); break; \ 357 case 8: pscr2_ret__ = stem##8(variable, __VA_ARGS__); break; \ 358 default: \ 359 __bad_size_call_parameter(); break; \ 360 } \ 361 pscr2_ret__; \ 362 }) 363 364 #define __pcpu_size_call(stem, variable, ...) \ 365 do { \ 366 __verify_pcpu_ptr(&(variable)); \ 367 switch(sizeof(variable)) { \ 368 case 1: stem##1(variable, __VA_ARGS__);break; \ 369 case 2: stem##2(variable, __VA_ARGS__);break; \ 370 case 4: stem##4(variable, __VA_ARGS__);break; \ 371 case 8: stem##8(variable, __VA_ARGS__);break; \ 372 default: \ 373 __bad_size_call_parameter();break; \ 374 } \ 375 } while (0) 376 377 /* 378 * this_cpu operations (C) 2008-2013 Christoph Lameter <[email protected]> 379 * 380 * Optimized manipulation for memory allocated through the per cpu 381 * allocator or for addresses of per cpu variables. 382 * 383 * These operation guarantee exclusivity of access for other operations 384 * on the *same* processor. The assumption is that per cpu data is only 385 * accessed by a single processor instance (the current one). 386 * 387 * The arch code can provide optimized implementation by defining macros 388 * for certain scalar sizes. F.e. provide this_cpu_add_2() to provide per 389 * cpu atomic operations for 2 byte sized RMW actions. If arch code does 390 * not provide operations for a scalar size then the fallback in the 391 * generic code will be used. 392 * 393 * cmpxchg_double replaces two adjacent scalars at once. The first two 394 * parameters are per cpu variables which have to be of the same size. A 395 * truth value is returned to indicate success or failure (since a double 396 * register result is difficult to handle). There is very limited hardware 397 * support for these operations, so only certain sizes may work. 398 */ 399 400 /* 401 * Operations for contexts where we do not want to do any checks for 402 * preemptions. Unless strictly necessary, always use [__]this_cpu_*() 403 * instead. 404 * 405 * If there is no other protection through preempt disable and/or disabling 406 * interrupts then one of these RMW operations can show unexpected behavior 407 * because the execution thread was rescheduled on another processor or an 408 * interrupt occurred and the same percpu variable was modified from the 409 * interrupt context. 410 */ 411 #define raw_cpu_read(pcp) __pcpu_size_call_return(raw_cpu_read_, pcp) 412 #define raw_cpu_write(pcp, val) __pcpu_size_call(raw_cpu_write_, pcp, val) 413 #define raw_cpu_add(pcp, val) __pcpu_size_call(raw_cpu_add_, pcp, val) 414 #define raw_cpu_and(pcp, val) __pcpu_size_call(raw_cpu_and_, pcp, val) 415 #define raw_cpu_or(pcp, val) __pcpu_size_call(raw_cpu_or_, pcp, val) 416 #define raw_cpu_add_return(pcp, val) __pcpu_size_call_return2(raw_cpu_add_return_, pcp, val) 417 #define raw_cpu_xchg(pcp, nval) __pcpu_size_call_return2(raw_cpu_xchg_, pcp, nval) 418 #define raw_cpu_cmpxchg(pcp, oval, nval) \ 419 __pcpu_size_call_return2(raw_cpu_cmpxchg_, pcp, oval, nval) 420 #define raw_cpu_try_cmpxchg(pcp, ovalp, nval) \ 421 __pcpu_size_call_return2bool(raw_cpu_try_cmpxchg_, pcp, ovalp, nval) 422 #define raw_cpu_sub(pcp, val) raw_cpu_add(pcp, -(val)) 423 #define raw_cpu_inc(pcp) raw_cpu_add(pcp, 1) 424 #define raw_cpu_dec(pcp) raw_cpu_sub(pcp, 1) 425 #define raw_cpu_sub_return(pcp, val) raw_cpu_add_return(pcp, -(typeof(pcp))(val)) 426 #define raw_cpu_inc_return(pcp) raw_cpu_add_return(pcp, 1) 427 #define raw_cpu_dec_return(pcp) raw_cpu_add_return(pcp, -1) 428 429 /* 430 * Operations for contexts that are safe from preemption/interrupts. These 431 * operations verify that preemption is disabled. 432 */ 433 #define __this_cpu_read(pcp) \ 434 ({ \ 435 __this_cpu_preempt_check("read"); \ 436 raw_cpu_read(pcp); \ 437 }) 438 439 #define __this_cpu_write(pcp, val) \ 440 ({ \ 441 __this_cpu_preempt_check("write"); \ 442 raw_cpu_write(pcp, val); \ 443 }) 444 445 #define __this_cpu_add(pcp, val) \ 446 ({ \ 447 __this_cpu_preempt_check("add"); \ 448 raw_cpu_add(pcp, val); \ 449 }) 450 451 #define __this_cpu_and(pcp, val) \ 452 ({ \ 453 __this_cpu_preempt_check("and"); \ 454 raw_cpu_and(pcp, val); \ 455 }) 456 457 #define __this_cpu_or(pcp, val) \ 458 ({ \ 459 __this_cpu_preempt_check("or"); \ 460 raw_cpu_or(pcp, val); \ 461 }) 462 463 #define __this_cpu_add_return(pcp, val) \ 464 ({ \ 465 __this_cpu_preempt_check("add_return"); \ 466 raw_cpu_add_return(pcp, val); \ 467 }) 468 469 #define __this_cpu_xchg(pcp, nval) \ 470 ({ \ 471 __this_cpu_preempt_check("xchg"); \ 472 raw_cpu_xchg(pcp, nval); \ 473 }) 474 475 #define __this_cpu_cmpxchg(pcp, oval, nval) \ 476 ({ \ 477 __this_cpu_preempt_check("cmpxchg"); \ 478 raw_cpu_cmpxchg(pcp, oval, nval); \ 479 }) 480 481 #define __this_cpu_try_cmpxchg(pcp, ovalp, nval) \ 482 ({ \ 483 __this_cpu_preempt_check("try_cmpxchg"); \ 484 raw_cpu_try_cmpxchg(pcp, ovalp, nval); \ 485 }) 486 487 #define __this_cpu_sub(pcp, val) __this_cpu_add(pcp, -(typeof(pcp))(val)) 488 #define __this_cpu_inc(pcp) __this_cpu_add(pcp, 1) 489 #define __this_cpu_dec(pcp) __this_cpu_sub(pcp, 1) 490 #define __this_cpu_sub_return(pcp, val) __this_cpu_add_return(pcp, -(typeof(pcp))(val)) 491 #define __this_cpu_inc_return(pcp) __this_cpu_add_return(pcp, 1) 492 #define __this_cpu_dec_return(pcp) __this_cpu_add_return(pcp, -1) 493 494 /* 495 * Operations with implied preemption/interrupt protection. These 496 * operations can be used without worrying about preemption or interrupt. 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_try_cmpxchg(pcp, ovalp, nval) \ 508 __pcpu_size_call_return2bool(this_cpu_try_cmpxchg_, pcp, ovalp, nval) 509 #define this_cpu_sub(pcp, val) this_cpu_add(pcp, -(typeof(pcp))(val)) 510 #define this_cpu_inc(pcp) this_cpu_add(pcp, 1) 511 #define this_cpu_dec(pcp) this_cpu_sub(pcp, 1) 512 #define this_cpu_sub_return(pcp, val) this_cpu_add_return(pcp, -(typeof(pcp))(val)) 513 #define this_cpu_inc_return(pcp) this_cpu_add_return(pcp, 1) 514 #define this_cpu_dec_return(pcp) this_cpu_add_return(pcp, -1) 515 516 #endif /* __ASSEMBLY__ */ 517 #endif /* _LINUX_PERCPU_DEFS_H */ 518