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 <stdint.h> 12 #include <stdbool.h> 13 #include <pthread.h> 14 #include <signal.h> 15 #include <sched.h> 16 #include <errno.h> 17 #include <stdio.h> 18 #include <stdlib.h> 19 #include <linux/rseq.h> 20 21 /* 22 * Empty code injection macros, override when testing. 23 * It is important to consider that the ASM injection macros need to be 24 * fully reentrant (e.g. do not modify the stack). 25 */ 26 #ifndef RSEQ_INJECT_ASM 27 #define RSEQ_INJECT_ASM(n) 28 #endif 29 30 #ifndef RSEQ_INJECT_C 31 #define RSEQ_INJECT_C(n) 32 #endif 33 34 #ifndef RSEQ_INJECT_INPUT 35 #define RSEQ_INJECT_INPUT 36 #endif 37 38 #ifndef RSEQ_INJECT_CLOBBER 39 #define RSEQ_INJECT_CLOBBER 40 #endif 41 42 #ifndef RSEQ_INJECT_FAILED 43 #define RSEQ_INJECT_FAILED 44 #endif 45 46 extern __thread volatile struct rseq __rseq_abi; 47 48 #define rseq_likely(x) __builtin_expect(!!(x), 1) 49 #define rseq_unlikely(x) __builtin_expect(!!(x), 0) 50 #define rseq_barrier() __asm__ __volatile__("" : : : "memory") 51 52 #define RSEQ_ACCESS_ONCE(x) (*(__volatile__ __typeof__(x) *)&(x)) 53 #define RSEQ_WRITE_ONCE(x, v) __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); }) 54 #define RSEQ_READ_ONCE(x) RSEQ_ACCESS_ONCE(x) 55 56 #define __rseq_str_1(x) #x 57 #define __rseq_str(x) __rseq_str_1(x) 58 59 #define rseq_log(fmt, args...) \ 60 fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \ 61 ## args, __func__) 62 63 #define rseq_bug(fmt, args...) \ 64 do { \ 65 rseq_log(fmt, ##args); \ 66 abort(); \ 67 } while (0) 68 69 #if defined(__x86_64__) || defined(__i386__) 70 #include <rseq-x86.h> 71 #elif defined(__ARMEL__) 72 #include <rseq-arm.h> 73 #elif defined (__AARCH64EL__) 74 #include <rseq-arm64.h> 75 #elif defined(__PPC__) 76 #include <rseq-ppc.h> 77 #elif defined(__mips__) 78 #include <rseq-mips.h> 79 #elif defined(__s390__) 80 #include <rseq-s390.h> 81 #else 82 #error unsupported target 83 #endif 84 85 /* 86 * Register rseq for the current thread. This needs to be called once 87 * by any thread which uses restartable sequences, before they start 88 * using restartable sequences, to ensure restartable sequences 89 * succeed. A restartable sequence executed from a non-registered 90 * thread will always fail. 91 */ 92 int rseq_register_current_thread(void); 93 94 /* 95 * Unregister rseq for current thread. 96 */ 97 int rseq_unregister_current_thread(void); 98 99 /* 100 * Restartable sequence fallback for reading the current CPU number. 101 */ 102 int32_t rseq_fallback_current_cpu(void); 103 104 /* 105 * Values returned can be either the current CPU number, -1 (rseq is 106 * uninitialized), or -2 (rseq initialization has failed). 107 */ 108 static inline int32_t rseq_current_cpu_raw(void) 109 { 110 return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id); 111 } 112 113 /* 114 * Returns a possible CPU number, which is typically the current CPU. 115 * The returned CPU number can be used to prepare for an rseq critical 116 * section, which will confirm whether the cpu number is indeed the 117 * current one, and whether rseq is initialized. 118 * 119 * The CPU number returned by rseq_cpu_start should always be validated 120 * by passing it to a rseq asm sequence, or by comparing it to the 121 * return value of rseq_current_cpu_raw() if the rseq asm sequence 122 * does not need to be invoked. 123 */ 124 static inline uint32_t rseq_cpu_start(void) 125 { 126 return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id_start); 127 } 128 129 static inline uint32_t rseq_current_cpu(void) 130 { 131 int32_t cpu; 132 133 cpu = rseq_current_cpu_raw(); 134 if (rseq_unlikely(cpu < 0)) 135 cpu = rseq_fallback_current_cpu(); 136 return cpu; 137 } 138 139 static inline void rseq_clear_rseq_cs(void) 140 { 141 #ifdef __LP64__ 142 __rseq_abi.rseq_cs.ptr = 0; 143 #else 144 __rseq_abi.rseq_cs.ptr.ptr32 = 0; 145 #endif 146 } 147 148 /* 149 * rseq_prepare_unload() should be invoked by each thread executing a rseq 150 * critical section at least once between their last critical section and 151 * library unload of the library defining the rseq critical section 152 * (struct rseq_cs). This also applies to use of rseq in code generated by 153 * JIT: rseq_prepare_unload() should be invoked at least once by each 154 * thread executing a rseq critical section before reclaim of the memory 155 * holding the struct rseq_cs. 156 */ 157 static inline void rseq_prepare_unload(void) 158 { 159 rseq_clear_rseq_cs(); 160 } 161 162 #endif /* RSEQ_H_ */ 163