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 #elif defined(__mips__) 77 #include <rseq-mips.h> 78 #else 79 #error unsupported target 80 #endif 81 82 /* 83 * Register rseq for the current thread. This needs to be called once 84 * by any thread which uses restartable sequences, before they start 85 * using restartable sequences, to ensure restartable sequences 86 * succeed. A restartable sequence executed from a non-registered 87 * thread will always fail. 88 */ 89 int rseq_register_current_thread(void); 90 91 /* 92 * Unregister rseq for current thread. 93 */ 94 int rseq_unregister_current_thread(void); 95 96 /* 97 * Restartable sequence fallback for reading the current CPU number. 98 */ 99 int32_t rseq_fallback_current_cpu(void); 100 101 /* 102 * Values returned can be either the current CPU number, -1 (rseq is 103 * uninitialized), or -2 (rseq initialization has failed). 104 */ 105 static inline int32_t rseq_current_cpu_raw(void) 106 { 107 return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id); 108 } 109 110 /* 111 * Returns a possible CPU number, which is typically the current CPU. 112 * The returned CPU number can be used to prepare for an rseq critical 113 * section, which will confirm whether the cpu number is indeed the 114 * current one, and whether rseq is initialized. 115 * 116 * The CPU number returned by rseq_cpu_start should always be validated 117 * by passing it to a rseq asm sequence, or by comparing it to the 118 * return value of rseq_current_cpu_raw() if the rseq asm sequence 119 * does not need to be invoked. 120 */ 121 static inline uint32_t rseq_cpu_start(void) 122 { 123 return RSEQ_ACCESS_ONCE(__rseq_abi.cpu_id_start); 124 } 125 126 static inline uint32_t rseq_current_cpu(void) 127 { 128 int32_t cpu; 129 130 cpu = rseq_current_cpu_raw(); 131 if (rseq_unlikely(cpu < 0)) 132 cpu = rseq_fallback_current_cpu(); 133 return cpu; 134 } 135 136 /* 137 * rseq_prepare_unload() should be invoked by each thread using rseq_finish*() 138 * at least once between their last rseq_finish*() and library unload of the 139 * library defining the rseq critical section (struct rseq_cs). This also 140 * applies to use of rseq in code generated by JIT: rseq_prepare_unload() 141 * should be invoked at least once by each thread using rseq_finish*() before 142 * reclaim of the memory holding the struct rseq_cs. 143 */ 144 static inline void rseq_prepare_unload(void) 145 { 146 __rseq_abi.rseq_cs = 0; 147 } 148 149 #endif /* RSEQ_H_ */ 150