| 1 | /* |
| 2 | * rseq.h |
| 3 | * |
| 4 | * (C) Copyright 2016 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | * |
| 6 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| 7 | * of this software and associated documentation files (the "Software"), to deal |
| 8 | * in the Software without restriction, including without limitation the rights |
| 9 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 10 | * copies of the Software, and to permit persons to whom the Software is |
| 11 | * furnished to do so, subject to the following conditions: |
| 12 | * |
| 13 | * The above copyright notice and this permission notice shall be included in |
| 14 | * all copies or substantial portions of the Software. |
| 15 | * |
| 16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 17 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 19 | * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 20 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 21 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| 22 | * SOFTWARE. |
| 23 | */ |
| 24 | |
| 25 | #ifndef RSEQ_H |
| 26 | #define RSEQ_H |
| 27 | |
| 28 | #include <stdint.h> |
| 29 | #include <stdbool.h> |
| 30 | #include <pthread.h> |
| 31 | #include <signal.h> |
| 32 | #include <sched.h> |
| 33 | #include <errno.h> |
| 34 | #include <stdio.h> |
| 35 | #include <stdlib.h> |
| 36 | #include <sched.h> |
| 37 | #include <unistd.h> |
| 38 | #include <urcu/compiler.h> |
| 39 | #include <urcu/system.h> |
| 40 | #include <urcu/arch.h> |
| 41 | #include <lttng/ringbuffer-config.h> /* for struct lttng_rseq_state */ |
| 42 | #include "linux-rseq-abi.h" |
| 43 | |
| 44 | /* |
| 45 | * Empty code injection macros, override when testing. |
| 46 | * It is important to consider that the ASM injection macros need to be |
| 47 | * fully reentrant (e.g. do not modify the stack). |
| 48 | */ |
| 49 | #ifndef RSEQ_INJECT_ASM |
| 50 | #define RSEQ_INJECT_ASM(n) |
| 51 | #endif |
| 52 | |
| 53 | #ifndef RSEQ_INJECT_C |
| 54 | #define RSEQ_INJECT_C(n) |
| 55 | #endif |
| 56 | |
| 57 | #ifndef RSEQ_INJECT_INPUT |
| 58 | #define RSEQ_INJECT_INPUT |
| 59 | #endif |
| 60 | |
| 61 | #ifndef RSEQ_INJECT_CLOBBER |
| 62 | #define RSEQ_INJECT_CLOBBER |
| 63 | #endif |
| 64 | |
| 65 | #ifndef RSEQ_INJECT_FAILED |
| 66 | #define RSEQ_INJECT_FAILED |
| 67 | #endif |
| 68 | |
| 69 | #ifndef RSEQ_FALLBACK_CNT |
| 70 | #define RSEQ_FALLBACK_CNT 3 |
| 71 | #endif |
| 72 | |
| 73 | extern __thread volatile struct rseq __rseq_abi; |
| 74 | |
| 75 | #if defined(__x86_64__) || defined(__i386__) |
| 76 | #include "rseq-x86.h" |
| 77 | #ifdef __NR_rseq |
| 78 | #define ARCH_HAS_RSEQ 1 |
| 79 | #endif |
| 80 | #elif defined(__ARMEL__) |
| 81 | #include "rseq-arm.h" |
| 82 | #ifdef __NR_rseq |
| 83 | #define ARCH_HAS_RSEQ 1 |
| 84 | #endif |
| 85 | #elif defined(__PPC__) |
| 86 | #include "rseq-ppc.h" |
| 87 | #ifdef __NR_rseq |
| 88 | #define ARCH_HAS_RSEQ 1 |
| 89 | #endif |
| 90 | #else |
| 91 | #error unsupported target |
| 92 | #endif |
| 93 | |
| 94 | /* |
| 95 | * Register rseq for the current thread. This needs to be called once |
| 96 | * by any thread which uses restartable sequences, before they start |
| 97 | * using restartable sequences. |
| 98 | */ |
| 99 | int rseq_register_current_thread(void); |
| 100 | |
| 101 | /* |
| 102 | * Unregister rseq for current thread. |
| 103 | */ |
| 104 | int rseq_unregister_current_thread(void); |
| 105 | |
| 106 | void rseq_init(void); |
| 107 | void rseq_destroy(void); |
| 108 | |
| 109 | static inline int32_t rseq_cpu_at_start(struct lttng_rseq_state start_value) |
| 110 | { |
| 111 | return start_value.cpu_id; |
| 112 | } |
| 113 | |
| 114 | static inline int32_t rseq_current_cpu_raw(void) |
| 115 | { |
| 116 | return CMM_LOAD_SHARED(__rseq_abi.u.e.cpu_id); |
| 117 | } |
| 118 | |
| 119 | #ifdef ARCH_HAS_RSEQ |
| 120 | static inline __attribute__((always_inline)) |
| 121 | struct lttng_rseq_state rseq_start(void) |
| 122 | { |
| 123 | struct lttng_rseq_state result; |
| 124 | |
| 125 | result.rseqp = &__rseq_abi; |
| 126 | if (has_single_copy_load_64()) { |
| 127 | union rseq_cpu_event u; |
| 128 | |
| 129 | u.v = CMM_LOAD_SHARED(result.rseqp->u.v); |
| 130 | result.event_counter = u.e.event_counter; |
| 131 | result.cpu_id = u.e.cpu_id; |
| 132 | } else { |
| 133 | result.event_counter = |
| 134 | CMM_LOAD_SHARED(result.rseqp->u.e.event_counter); |
| 135 | /* load event_counter before cpu_id. */ |
| 136 | RSEQ_INJECT_C(6) |
| 137 | result.cpu_id = CMM_LOAD_SHARED(result.rseqp->u.e.cpu_id); |
| 138 | } |
| 139 | /* |
| 140 | * Read event counter before lock state and cpu_id. This ensures |
| 141 | * that when the state changes from RESTART to LOCK, if we have |
| 142 | * some threads that have already seen the RESTART still in |
| 143 | * flight, they will necessarily be preempted/signalled before a |
| 144 | * thread can see the LOCK state for that same CPU. That |
| 145 | * preemption/signalling will cause them to restart, so they |
| 146 | * don't interfere with the lock. |
| 147 | */ |
| 148 | RSEQ_INJECT_C(7) |
| 149 | |
| 150 | /* |
| 151 | * Ensure the compiler does not re-order loads of protected |
| 152 | * values before we load the event counter. |
| 153 | */ |
| 154 | cmm_barrier(); |
| 155 | return result; |
| 156 | } |
| 157 | #else |
| 158 | static inline __attribute__((always_inline)) |
| 159 | struct lttng_rseq_state rseq_start(void) |
| 160 | { |
| 161 | struct lttng_rseq_state result = { |
| 162 | .cpu_id = -2, |
| 163 | }; |
| 164 | return result; |
| 165 | } |
| 166 | #endif |
| 167 | |
| 168 | enum rseq_finish_type { |
| 169 | RSEQ_FINISH_SINGLE, |
| 170 | RSEQ_FINISH_TWO, |
| 171 | RSEQ_FINISH_MEMCPY, |
| 172 | }; |
| 173 | |
| 174 | /* |
| 175 | * p_spec and to_write_spec are used for a speculative write attempted |
| 176 | * near the end of the restartable sequence. A rseq_finish2 may fail |
| 177 | * even after this write takes place. |
| 178 | * |
| 179 | * p_final and to_write_final are used for the final write. If this |
| 180 | * write takes place, the rseq_finish2 is guaranteed to succeed. |
| 181 | */ |
| 182 | #ifdef ARCH_HAS_RSEQ |
| 183 | static inline __attribute__((always_inline)) |
| 184 | bool __rseq_finish(intptr_t *p_spec, intptr_t to_write_spec, |
| 185 | void *p_memcpy, void *to_write_memcpy, size_t len_memcpy, |
| 186 | intptr_t *p_final, intptr_t to_write_final, |
| 187 | struct lttng_rseq_state start_value, |
| 188 | enum rseq_finish_type type, bool release) |
| 189 | { |
| 190 | RSEQ_INJECT_C(9) |
| 191 | |
| 192 | switch (type) { |
| 193 | case RSEQ_FINISH_SINGLE: |
| 194 | RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure, |
| 195 | /* no speculative write */, /* no speculative write */, |
| 196 | RSEQ_FINISH_FINAL_STORE_ASM(), |
| 197 | RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final), |
| 198 | /* no extra clobber */, /* no arg */, /* no arg */, |
| 199 | /* no arg */ |
| 200 | ); |
| 201 | break; |
| 202 | case RSEQ_FINISH_TWO: |
| 203 | if (release) { |
| 204 | RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure, |
| 205 | RSEQ_FINISH_SPECULATIVE_STORE_ASM(), |
| 206 | RSEQ_FINISH_SPECULATIVE_STORE_INPUT(p_spec, to_write_spec), |
| 207 | RSEQ_FINISH_FINAL_STORE_RELEASE_ASM(), |
| 208 | RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final), |
| 209 | /* no extra clobber */, /* no arg */, /* no arg */, |
| 210 | /* no arg */ |
| 211 | ); |
| 212 | } else { |
| 213 | RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure, |
| 214 | RSEQ_FINISH_SPECULATIVE_STORE_ASM(), |
| 215 | RSEQ_FINISH_SPECULATIVE_STORE_INPUT(p_spec, to_write_spec), |
| 216 | RSEQ_FINISH_FINAL_STORE_ASM(), |
| 217 | RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final), |
| 218 | /* no extra clobber */, /* no arg */, /* no arg */, |
| 219 | /* no arg */ |
| 220 | ); |
| 221 | } |
| 222 | break; |
| 223 | case RSEQ_FINISH_MEMCPY: |
| 224 | if (release) { |
| 225 | RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure, |
| 226 | RSEQ_FINISH_MEMCPY_STORE_ASM(), |
| 227 | RSEQ_FINISH_MEMCPY_STORE_INPUT(p_memcpy, to_write_memcpy, len_memcpy), |
| 228 | RSEQ_FINISH_FINAL_STORE_RELEASE_ASM(), |
| 229 | RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final), |
| 230 | RSEQ_FINISH_MEMCPY_CLOBBER(), |
| 231 | RSEQ_FINISH_MEMCPY_SETUP(), |
| 232 | RSEQ_FINISH_MEMCPY_TEARDOWN(), |
| 233 | RSEQ_FINISH_MEMCPY_SCRATCH() |
| 234 | ); |
| 235 | } else { |
| 236 | RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure, |
| 237 | RSEQ_FINISH_MEMCPY_STORE_ASM(), |
| 238 | RSEQ_FINISH_MEMCPY_STORE_INPUT(p_memcpy, to_write_memcpy, len_memcpy), |
| 239 | RSEQ_FINISH_FINAL_STORE_ASM(), |
| 240 | RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final), |
| 241 | RSEQ_FINISH_MEMCPY_CLOBBER(), |
| 242 | RSEQ_FINISH_MEMCPY_SETUP(), |
| 243 | RSEQ_FINISH_MEMCPY_TEARDOWN(), |
| 244 | RSEQ_FINISH_MEMCPY_SCRATCH() |
| 245 | ); |
| 246 | } |
| 247 | break; |
| 248 | } |
| 249 | return true; |
| 250 | failure: |
| 251 | RSEQ_INJECT_FAILED |
| 252 | return false; |
| 253 | } |
| 254 | #else |
| 255 | static inline __attribute__((always_inline)) |
| 256 | bool __rseq_finish(intptr_t *p_spec, intptr_t to_write_spec, |
| 257 | void *p_memcpy, void *to_write_memcpy, size_t len_memcpy, |
| 258 | intptr_t *p_final, intptr_t to_write_final, |
| 259 | struct lttng_rseq_state start_value, |
| 260 | enum rseq_finish_type type, bool release) |
| 261 | { |
| 262 | return false; |
| 263 | } |
| 264 | #endif |
| 265 | |
| 266 | static inline __attribute__((always_inline)) |
| 267 | bool rseq_finish(intptr_t *p, intptr_t to_write, |
| 268 | struct lttng_rseq_state start_value) |
| 269 | { |
| 270 | return __rseq_finish(NULL, 0, |
| 271 | NULL, NULL, 0, |
| 272 | p, to_write, start_value, |
| 273 | RSEQ_FINISH_SINGLE, false); |
| 274 | } |
| 275 | |
| 276 | static inline __attribute__((always_inline)) |
| 277 | bool rseq_finish2(intptr_t *p_spec, intptr_t to_write_spec, |
| 278 | intptr_t *p_final, intptr_t to_write_final, |
| 279 | struct lttng_rseq_state start_value) |
| 280 | { |
| 281 | return __rseq_finish(p_spec, to_write_spec, |
| 282 | NULL, NULL, 0, |
| 283 | p_final, to_write_final, start_value, |
| 284 | RSEQ_FINISH_TWO, false); |
| 285 | } |
| 286 | |
| 287 | static inline __attribute__((always_inline)) |
| 288 | bool rseq_finish2_release(intptr_t *p_spec, intptr_t to_write_spec, |
| 289 | intptr_t *p_final, intptr_t to_write_final, |
| 290 | struct lttng_rseq_state start_value) |
| 291 | { |
| 292 | return __rseq_finish(p_spec, to_write_spec, |
| 293 | NULL, NULL, 0, |
| 294 | p_final, to_write_final, start_value, |
| 295 | RSEQ_FINISH_TWO, true); |
| 296 | } |
| 297 | |
| 298 | static inline __attribute__((always_inline)) |
| 299 | bool rseq_finish_memcpy(void *p_memcpy, void *to_write_memcpy, |
| 300 | size_t len_memcpy, intptr_t *p_final, intptr_t to_write_final, |
| 301 | struct lttng_rseq_state start_value) |
| 302 | { |
| 303 | return __rseq_finish(NULL, 0, |
| 304 | p_memcpy, to_write_memcpy, len_memcpy, |
| 305 | p_final, to_write_final, start_value, |
| 306 | RSEQ_FINISH_MEMCPY, false); |
| 307 | } |
| 308 | |
| 309 | static inline __attribute__((always_inline)) |
| 310 | bool rseq_finish_memcpy_release(void *p_memcpy, void *to_write_memcpy, |
| 311 | size_t len_memcpy, intptr_t *p_final, intptr_t to_write_final, |
| 312 | struct lttng_rseq_state start_value) |
| 313 | { |
| 314 | return __rseq_finish(NULL, 0, |
| 315 | p_memcpy, to_write_memcpy, len_memcpy, |
| 316 | p_final, to_write_final, start_value, |
| 317 | RSEQ_FINISH_MEMCPY, true); |
| 318 | } |
| 319 | |
| 320 | #endif /* RSEQ_H_ */ |