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 <sched.h> 20 #include <linux/rseq.h> 21 22 /* 23 * Empty code injection macros, override when testing. 24 * It is important to consider that the ASM injection macros need to be 25 * fully reentrant (e.g. do not modify the stack). 26 */ 27 #ifndef RSEQ_INJECT_ASM 28 #define RSEQ_INJECT_ASM(n) 29 #endif 30 31 #ifndef RSEQ_INJECT_C 32 #define RSEQ_INJECT_C(n) 33 #endif 34 35 #ifndef RSEQ_INJECT_INPUT 36 #define RSEQ_INJECT_INPUT 37 #endif 38 39 #ifndef RSEQ_INJECT_CLOBBER 40 #define RSEQ_INJECT_CLOBBER 41 #endif 42 43 #ifndef RSEQ_INJECT_FAILED 44 #define RSEQ_INJECT_FAILED 45 #endif 46 47 extern __thread volatile struct rseq __rseq_abi; 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(__PPC__) 75 #include <rseq-ppc.h> 76 #else 77 #error unsupported target 78 #endif 79 80 /* 81 * Register rseq for the current thread. This needs to be called once 82 * by any thread which uses restartable sequences, before they start 83 * using restartable sequences, to ensure restartable sequences 84 * succeed. A restartable sequence executed from a non-registered 85 * thread will always fail. 86 */ 87 int rseq_register_current_thread(void); 88 89 /* 90 * Unregister rseq for current thread. 91 */ 92 int rseq_unregister_current_thread(void); 93 94 /* 95 * Restartable sequence fallback for reading the current CPU number. 96 */ 97 int32_t rseq_fallback_current_cpu(void); 98 99 /* 100 * Values returned can be either the current CPU number, -1 (rseq is 101 * uninitialized), or -2 (rseq initialization has failed). 102 */ 103 static inline int32_t rseq_current_cpu_raw(void) 104 { 105 return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id); 106 } 107 108 /* 109 * Returns a possible CPU number, which is typically the current CPU. 110 * The returned CPU number can be used to prepare for an rseq critical 111 * section, which will confirm whether the cpu number is indeed the 112 * current one, and whether rseq is initialized. 113 * 114 * The CPU number returned by rseq_cpu_start should always be validated 115 * by passing it to a rseq asm sequence, or by comparing it to the 116 * return value of rseq_current_cpu_raw() if the rseq asm sequence 117 * does not need to be invoked. 118 */ 119 static inline uint32_t rseq_cpu_start(void) 120 { 121 return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id_start); 122 } 123 124 static inline uint32_t rseq_current_cpu(void) 125 { 126 int32_t cpu; 127 128 cpu = rseq_current_cpu_raw(); 129 if (rseq_unlikely(cpu < 0)) 130 cpu = rseq_fallback_current_cpu(); 131 return cpu; 132 } 133 134 /* 135 * rseq_prepare_unload() should be invoked by each thread using rseq_finish*() 136 * at least once between their last rseq_finish*() and library unload of the 137 * library defining the rseq critical section (struct rseq_cs). This also 138 * applies to use of rseq in code generated by JIT: rseq_prepare_unload() 139 * should be invoked at least once by each thread using rseq_finish*() before 140 * reclaim of the memory holding the struct rseq_cs. 141 */ 142 static inline void rseq_prepare_unload(void) 143 { 144 __rseq_abi.rseq_cs = 0; 145 } 146 147 #endif /* RSEQ_H_ */ 148