1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */ 2 /* 3 * rseq.h 4 * 5 * (C) Copyright 2016-2018 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> 6 */ 7 8 #ifndef RSEQ_H 9 #define RSEQ_H 10 11 #include <assert.h> 12 #include <stdint.h> 13 #include <stdbool.h> 14 #include <pthread.h> 15 #include <signal.h> 16 #include <sched.h> 17 #include <errno.h> 18 #include <stdio.h> 19 #include <stdlib.h> 20 #include <stddef.h> 21 #include "rseq-abi.h" 22 #include "compiler.h" 23 24 #ifndef rseq_sizeof_field 25 #define rseq_sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER)) 26 #endif 27 28 #ifndef rseq_offsetofend 29 #define rseq_offsetofend(TYPE, MEMBER) \ 30 (offsetof(TYPE, MEMBER) + rseq_sizeof_field(TYPE, MEMBER)) 31 #endif 32 33 /* 34 * Empty code injection macros, override when testing. 35 * It is important to consider that the ASM injection macros need to be 36 * fully reentrant (e.g. do not modify the stack). 37 */ 38 #ifndef RSEQ_INJECT_ASM 39 #define RSEQ_INJECT_ASM(n) 40 #endif 41 42 #ifndef RSEQ_INJECT_C 43 #define RSEQ_INJECT_C(n) 44 #endif 45 46 #ifndef RSEQ_INJECT_INPUT 47 #define RSEQ_INJECT_INPUT 48 #endif 49 50 #ifndef RSEQ_INJECT_CLOBBER 51 #define RSEQ_INJECT_CLOBBER 52 #endif 53 54 #ifndef RSEQ_INJECT_FAILED 55 #define RSEQ_INJECT_FAILED 56 #endif 57 58 #include "rseq-thread-pointer.h" 59 60 /* Offset from the thread pointer to the rseq area. */ 61 extern ptrdiff_t rseq_offset; 62 63 /* 64 * The rseq ABI is composed of extensible feature fields. The extensions 65 * are done by appending additional fields at the end of the structure. 66 * The rseq_size defines the size of the active feature set which can be 67 * used by the application for the current rseq registration. Features 68 * starting at offset >= rseq_size are inactive and should not be used. 69 * 70 * The rseq_size is the intersection between the available allocation 71 * size for the rseq area and the feature size supported by the kernel. 72 * unsuccessful. 73 */ 74 extern unsigned int rseq_size; 75 76 /* Flags used during rseq registration. */ 77 extern unsigned int rseq_flags; 78 79 enum rseq_mo { 80 RSEQ_MO_RELAXED = 0, 81 RSEQ_MO_CONSUME = 1, /* Unused */ 82 RSEQ_MO_ACQUIRE = 2, /* Unused */ 83 RSEQ_MO_RELEASE = 3, 84 RSEQ_MO_ACQ_REL = 4, /* Unused */ 85 RSEQ_MO_SEQ_CST = 5, /* Unused */ 86 }; 87 88 enum rseq_percpu_mode { 89 RSEQ_PERCPU_CPU_ID = 0, 90 RSEQ_PERCPU_MM_CID = 1, 91 }; 92 93 static inline struct rseq_abi *rseq_get_abi(void) 94 { 95 return (struct rseq_abi *) ((uintptr_t) rseq_thread_pointer() + rseq_offset); 96 } 97 98 #define rseq_likely(x) __builtin_expect(!!(x), 1) 99 #define rseq_unlikely(x) __builtin_expect(!!(x), 0) 100 #define rseq_barrier() __asm__ __volatile__("" : : : "memory") 101 102 #define RSEQ_ACCESS_ONCE(x) (*(__volatile__ __typeof__(x) *)&(x)) 103 #define RSEQ_WRITE_ONCE(x, v) __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); }) 104 #define RSEQ_READ_ONCE(x) RSEQ_ACCESS_ONCE(x) 105 106 #define __rseq_str_1(x) #x 107 #define __rseq_str(x) __rseq_str_1(x) 108 109 #define rseq_log(fmt, args...) \ 110 fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \ 111 ## args, __func__) 112 113 #define rseq_bug(fmt, args...) \ 114 do { \ 115 rseq_log(fmt, ##args); \ 116 abort(); \ 117 } while (0) 118 119 #if defined(__x86_64__) || defined(__i386__) 120 #include <rseq-x86.h> 121 #elif defined(__ARMEL__) 122 #include <rseq-arm.h> 123 #elif defined (__AARCH64EL__) 124 #include <rseq-arm64.h> 125 #elif defined(__PPC__) 126 #include <rseq-ppc.h> 127 #elif defined(__mips__) 128 #include <rseq-mips.h> 129 #elif defined(__s390__) 130 #include <rseq-s390.h> 131 #elif defined(__riscv) 132 #include <rseq-riscv.h> 133 #elif defined(__or1k__) 134 #include <rseq-or1k.h> 135 #else 136 #error unsupported target 137 #endif 138 139 /* 140 * Register rseq for the current thread. This needs to be called once 141 * by any thread which uses restartable sequences, before they start 142 * using restartable sequences, to ensure restartable sequences 143 * succeed. A restartable sequence executed from a non-registered 144 * thread will always fail. 145 */ 146 int __rseq_register_current_thread(bool nolibc, bool legacy); 147 148 static inline int rseq_register_current_thread(void) 149 { 150 return __rseq_register_current_thread(false, false); 151 } 152 153 /* 154 * Unregister rseq for current thread. 155 */ 156 int rseq_unregister_current_thread(void); 157 158 /* 159 * Restartable sequence fallback for reading the current CPU number. 160 */ 161 int32_t rseq_fallback_current_cpu(void); 162 163 /* 164 * Restartable sequence fallback for reading the current node number. 165 */ 166 int32_t rseq_fallback_current_node(void); 167 168 /* 169 * Returns true if rseq is supported. 170 */ 171 bool rseq_available(void); 172 173 /* 174 * Values returned can be either the current CPU number, -1 (rseq is 175 * uninitialized), or -2 (rseq initialization has failed). 176 */ 177 static inline int32_t rseq_current_cpu_raw(void) 178 { 179 return RSEQ_ACCESS_ONCE(rseq_get_abi()->cpu_id); 180 } 181 182 /* 183 * Returns a possible CPU number, which is typically the current CPU. 184 * The returned CPU number can be used to prepare for an rseq critical 185 * section, which will confirm whether the cpu number is indeed the 186 * current one, and whether rseq is initialized. 187 * 188 * The CPU number returned by rseq_cpu_start should always be validated 189 * by passing it to a rseq asm sequence, or by comparing it to the 190 * return value of rseq_current_cpu_raw() if the rseq asm sequence 191 * does not need to be invoked. 192 */ 193 static inline uint32_t rseq_cpu_start(void) 194 { 195 return RSEQ_ACCESS_ONCE(rseq_get_abi()->cpu_id_start); 196 } 197 198 static inline uint32_t rseq_current_cpu(void) 199 { 200 int32_t cpu; 201 202 cpu = rseq_current_cpu_raw(); 203 if (rseq_unlikely(cpu < 0)) 204 cpu = rseq_fallback_current_cpu(); 205 return cpu; 206 } 207 208 static inline bool rseq_node_id_available(void) 209 { 210 return (int) rseq_size >= rseq_offsetofend(struct rseq_abi, node_id); 211 } 212 213 /* 214 * Current NUMA node number. 215 */ 216 static inline uint32_t rseq_current_node_id(void) 217 { 218 assert(rseq_node_id_available()); 219 return RSEQ_ACCESS_ONCE(rseq_get_abi()->node_id); 220 } 221 222 static inline bool rseq_mm_cid_available(void) 223 { 224 return (int) rseq_size >= rseq_offsetofend(struct rseq_abi, mm_cid); 225 } 226 227 static inline uint32_t rseq_current_mm_cid(void) 228 { 229 return RSEQ_ACCESS_ONCE(rseq_get_abi()->mm_cid); 230 } 231 232 static inline void rseq_clear_rseq_cs(void) 233 { 234 RSEQ_WRITE_ONCE(rseq_get_abi()->rseq_cs.arch.ptr, 0); 235 } 236 237 /* 238 * rseq_prepare_unload() should be invoked by each thread executing a rseq 239 * critical section at least once between their last critical section and 240 * library unload of the library defining the rseq critical section (struct 241 * rseq_cs) or the code referred to by the struct rseq_cs start_ip and 242 * post_commit_offset fields. This also applies to use of rseq in code 243 * generated by JIT: rseq_prepare_unload() should be invoked at least once by 244 * each thread executing a rseq critical section before reclaim of the memory 245 * holding the struct rseq_cs or reclaim of the code pointed to by struct 246 * rseq_cs start_ip and post_commit_offset fields. 247 */ 248 static inline void rseq_prepare_unload(void) 249 { 250 rseq_clear_rseq_cs(); 251 } 252 253 static inline __attribute__((always_inline)) 254 int rseq_cmpeqv_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode, 255 intptr_t *v, intptr_t expect, 256 intptr_t newv, int cpu) 257 { 258 if (rseq_mo != RSEQ_MO_RELAXED) 259 return -1; 260 switch (percpu_mode) { 261 case RSEQ_PERCPU_CPU_ID: 262 return rseq_cmpeqv_storev_relaxed_cpu_id(v, expect, newv, cpu); 263 case RSEQ_PERCPU_MM_CID: 264 return rseq_cmpeqv_storev_relaxed_mm_cid(v, expect, newv, cpu); 265 } 266 return -1; 267 } 268 269 /* 270 * Compare @v against @expectnot. When it does _not_ match, load @v 271 * into @load, and store the content of *@v + voffp into @v. 272 */ 273 static inline __attribute__((always_inline)) 274 int rseq_cmpnev_storeoffp_load(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode, 275 intptr_t *v, intptr_t expectnot, long voffp, intptr_t *load, 276 int cpu) 277 { 278 if (rseq_mo != RSEQ_MO_RELAXED) 279 return -1; 280 switch (percpu_mode) { 281 case RSEQ_PERCPU_CPU_ID: 282 return rseq_cmpnev_storeoffp_load_relaxed_cpu_id(v, expectnot, voffp, load, cpu); 283 case RSEQ_PERCPU_MM_CID: 284 return rseq_cmpnev_storeoffp_load_relaxed_mm_cid(v, expectnot, voffp, load, cpu); 285 } 286 return -1; 287 } 288 289 static inline __attribute__((always_inline)) 290 int rseq_addv(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode, 291 intptr_t *v, intptr_t count, int cpu) 292 { 293 if (rseq_mo != RSEQ_MO_RELAXED) 294 return -1; 295 switch (percpu_mode) { 296 case RSEQ_PERCPU_CPU_ID: 297 return rseq_addv_relaxed_cpu_id(v, count, cpu); 298 case RSEQ_PERCPU_MM_CID: 299 return rseq_addv_relaxed_mm_cid(v, count, cpu); 300 } 301 return -1; 302 } 303 304 #ifdef RSEQ_ARCH_HAS_OFFSET_DEREF_ADDV 305 /* 306 * pval = *(ptr+off) 307 * *pval += inc; 308 */ 309 static inline __attribute__((always_inline)) 310 int rseq_offset_deref_addv(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode, 311 intptr_t *ptr, long off, intptr_t inc, int cpu) 312 { 313 if (rseq_mo != RSEQ_MO_RELAXED) 314 return -1; 315 switch (percpu_mode) { 316 case RSEQ_PERCPU_CPU_ID: 317 return rseq_offset_deref_addv_relaxed_cpu_id(ptr, off, inc, cpu); 318 case RSEQ_PERCPU_MM_CID: 319 return rseq_offset_deref_addv_relaxed_mm_cid(ptr, off, inc, cpu); 320 } 321 return -1; 322 } 323 #endif 324 325 static inline __attribute__((always_inline)) 326 int rseq_cmpeqv_trystorev_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode, 327 intptr_t *v, intptr_t expect, 328 intptr_t *v2, intptr_t newv2, 329 intptr_t newv, int cpu) 330 { 331 switch (rseq_mo) { 332 case RSEQ_MO_RELAXED: 333 switch (percpu_mode) { 334 case RSEQ_PERCPU_CPU_ID: 335 return rseq_cmpeqv_trystorev_storev_relaxed_cpu_id(v, expect, v2, newv2, newv, cpu); 336 case RSEQ_PERCPU_MM_CID: 337 return rseq_cmpeqv_trystorev_storev_relaxed_mm_cid(v, expect, v2, newv2, newv, cpu); 338 } 339 return -1; 340 case RSEQ_MO_RELEASE: 341 switch (percpu_mode) { 342 case RSEQ_PERCPU_CPU_ID: 343 return rseq_cmpeqv_trystorev_storev_release_cpu_id(v, expect, v2, newv2, newv, cpu); 344 case RSEQ_PERCPU_MM_CID: 345 return rseq_cmpeqv_trystorev_storev_release_mm_cid(v, expect, v2, newv2, newv, cpu); 346 } 347 return -1; 348 default: 349 return -1; 350 } 351 } 352 353 static inline __attribute__((always_inline)) 354 int rseq_cmpeqv_cmpeqv_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode, 355 intptr_t *v, intptr_t expect, 356 intptr_t *v2, intptr_t expect2, 357 intptr_t newv, int cpu) 358 { 359 if (rseq_mo != RSEQ_MO_RELAXED) 360 return -1; 361 switch (percpu_mode) { 362 case RSEQ_PERCPU_CPU_ID: 363 return rseq_cmpeqv_cmpeqv_storev_relaxed_cpu_id(v, expect, v2, expect2, newv, cpu); 364 case RSEQ_PERCPU_MM_CID: 365 return rseq_cmpeqv_cmpeqv_storev_relaxed_mm_cid(v, expect, v2, expect2, newv, cpu); 366 } 367 return -1; 368 } 369 370 static inline __attribute__((always_inline)) 371 int rseq_cmpeqv_trymemcpy_storev(enum rseq_mo rseq_mo, enum rseq_percpu_mode percpu_mode, 372 intptr_t *v, intptr_t expect, 373 void *dst, void *src, size_t len, 374 intptr_t newv, int cpu) 375 { 376 switch (rseq_mo) { 377 case RSEQ_MO_RELAXED: 378 switch (percpu_mode) { 379 case RSEQ_PERCPU_CPU_ID: 380 return rseq_cmpeqv_trymemcpy_storev_relaxed_cpu_id(v, expect, dst, src, len, newv, cpu); 381 case RSEQ_PERCPU_MM_CID: 382 return rseq_cmpeqv_trymemcpy_storev_relaxed_mm_cid(v, expect, dst, src, len, newv, cpu); 383 } 384 return -1; 385 case RSEQ_MO_RELEASE: 386 switch (percpu_mode) { 387 case RSEQ_PERCPU_CPU_ID: 388 return rseq_cmpeqv_trymemcpy_storev_release_cpu_id(v, expect, dst, src, len, newv, cpu); 389 case RSEQ_PERCPU_MM_CID: 390 return rseq_cmpeqv_trymemcpy_storev_release_mm_cid(v, expect, dst, src, len, newv, cpu); 391 } 392 return -1; 393 default: 394 return -1; 395 } 396 } 397 398 #endif /* RSEQ_H_ */ 399