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 extern int __rseq_handled; 48 49 #define rseq_likely(x) __builtin_expect(!!(x), 1) 50 #define rseq_unlikely(x) __builtin_expect(!!(x), 0) 51 #define rseq_barrier() __asm__ __volatile__("" : : : "memory") 52 53 #define RSEQ_ACCESS_ONCE(x) (*(__volatile__ __typeof__(x) *)&(x)) 54 #define RSEQ_WRITE_ONCE(x, v) __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); }) 55 #define RSEQ_READ_ONCE(x) RSEQ_ACCESS_ONCE(x) 56 57 #define __rseq_str_1(x) #x 58 #define __rseq_str(x) __rseq_str_1(x) 59 60 #define rseq_log(fmt, args...) \ 61 fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \ 62 ## args, __func__) 63 64 #define rseq_bug(fmt, args...) \ 65 do { \ 66 rseq_log(fmt, ##args); \ 67 abort(); \ 68 } while (0) 69 70 #if defined(__x86_64__) || defined(__i386__) 71 #include <rseq-x86.h> 72 #elif defined(__ARMEL__) 73 #include <rseq-arm.h> 74 #elif defined (__AARCH64EL__) 75 #include <rseq-arm64.h> 76 #elif defined(__PPC__) 77 #include <rseq-ppc.h> 78 #elif defined(__mips__) 79 #include <rseq-mips.h> 80 #elif defined(__s390__) 81 #include <rseq-s390.h> 82 #else 83 #error unsupported target 84 #endif 85 86 /* 87 * Register rseq for the current thread. This needs to be called once 88 * by any thread which uses restartable sequences, before they start 89 * using restartable sequences, to ensure restartable sequences 90 * succeed. A restartable sequence executed from a non-registered 91 * thread will always fail. 92 */ 93 int rseq_register_current_thread(void); 94 95 /* 96 * Unregister rseq for current thread. 97 */ 98 int rseq_unregister_current_thread(void); 99 100 /* 101 * Restartable sequence fallback for reading the current CPU number. 102 */ 103 int32_t rseq_fallback_current_cpu(void); 104 105 /* 106 * Values returned can be either the current CPU number, -1 (rseq is 107 * uninitialized), or -2 (rseq initialization has failed). 108 */ 109 static inline int32_t rseq_current_cpu_raw(void) 110 { 111 return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id); 112 } 113 114 /* 115 * Returns a possible CPU number, which is typically the current CPU. 116 * The returned CPU number can be used to prepare for an rseq critical 117 * section, which will confirm whether the cpu number is indeed the 118 * current one, and whether rseq is initialized. 119 * 120 * The CPU number returned by rseq_cpu_start should always be validated 121 * by passing it to a rseq asm sequence, or by comparing it to the 122 * return value of rseq_current_cpu_raw() if the rseq asm sequence 123 * does not need to be invoked. 124 */ 125 static inline uint32_t rseq_cpu_start(void) 126 { 127 return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id_start); 128 } 129 130 static inline uint32_t rseq_current_cpu(void) 131 { 132 int32_t cpu; 133 134 cpu = rseq_current_cpu_raw(); 135 if (rseq_unlikely(cpu < 0)) 136 cpu = rseq_fallback_current_cpu(); 137 return cpu; 138 } 139 140 static inline void rseq_clear_rseq_cs(void) 141 { 142 #ifdef __LP64__ 143 __rseq_abi.rseq_cs.ptr = 0; 144 #else 145 __rseq_abi.rseq_cs.ptr.ptr32 = 0; 146 #endif 147 } 148 149 /* 150 * rseq_prepare_unload() should be invoked by each thread executing a rseq 151 * critical section at least once between their last critical section and 152 * library unload of the library defining the rseq critical section 153 * (struct rseq_cs). This also applies to use of rseq in code generated by 154 * JIT: rseq_prepare_unload() should be invoked at least once by each 155 * thread executing a rseq critical section before reclaim of the memory 156 * holding the struct rseq_cs. 157 */ 158 static inline void rseq_prepare_unload(void) 159 { 160 rseq_clear_rseq_cs(); 161 } 162 163 #endif /* RSEQ_H_ */ 164