1 /* SPDX-License-Identifier: LGPL-2.1 OR MIT */
5 * (C) Copyright 2016-2018 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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).
26 #ifndef RSEQ_INJECT_ASM
27 #define RSEQ_INJECT_ASM(n)
31 #define RSEQ_INJECT_C(n)
34 #ifndef RSEQ_INJECT_INPUT
35 #define RSEQ_INJECT_INPUT
38 #ifndef RSEQ_INJECT_CLOBBER
39 #define RSEQ_INJECT_CLOBBER
42 #ifndef RSEQ_INJECT_FAILED
43 #define RSEQ_INJECT_FAILED
46 extern __thread struct rseq_abi __rseq_abi;
47 extern int __rseq_handled;
49 static inline struct rseq_abi *rseq_get_abi(void)
54 #define rseq_likely(x) __builtin_expect(!!(x), 1)
55 #define rseq_unlikely(x) __builtin_expect(!!(x), 0)
56 #define rseq_barrier() __asm__ __volatile__("" : : : "memory")
58 #define RSEQ_ACCESS_ONCE(x) (*(__volatile__ __typeof__(x) *)&(x))
59 #define RSEQ_WRITE_ONCE(x, v) __extension__ ({ RSEQ_ACCESS_ONCE(x) = (v); })
60 #define RSEQ_READ_ONCE(x) RSEQ_ACCESS_ONCE(x)
62 #define __rseq_str_1(x) #x
63 #define __rseq_str(x) __rseq_str_1(x)
65 #define rseq_log(fmt, args...) \
66 fprintf(stderr, fmt "(in %s() at " __FILE__ ":" __rseq_str(__LINE__)"\n", \
69 #define rseq_bug(fmt, args...) \
71 rseq_log(fmt, ##args); \
75 #if defined(__x86_64__) || defined(__i386__)
77 #elif defined(__ARMEL__)
79 #elif defined (__AARCH64EL__)
80 #include <rseq-arm64.h>
81 #elif defined(__PPC__)
83 #elif defined(__mips__)
84 #include <rseq-mips.h>
85 #elif defined(__s390__)
86 #include <rseq-s390.h>
88 #error unsupported target
92 * Register rseq for the current thread. This needs to be called once
93 * by any thread which uses restartable sequences, before they start
94 * using restartable sequences, to ensure restartable sequences
95 * succeed. A restartable sequence executed from a non-registered
96 * thread will always fail.
98 int rseq_register_current_thread(void);
101 * Unregister rseq for current thread.
103 int rseq_unregister_current_thread(void);
106 * Restartable sequence fallback for reading the current CPU number.
108 int32_t rseq_fallback_current_cpu(void);
111 * Values returned can be either the current CPU number, -1 (rseq is
112 * uninitialized), or -2 (rseq initialization has failed).
114 static inline int32_t rseq_current_cpu_raw(void)
116 return RSEQ_ACCESS_ONCE(rseq_get_abi()->cpu_id);
120 * Returns a possible CPU number, which is typically the current CPU.
121 * The returned CPU number can be used to prepare for an rseq critical
122 * section, which will confirm whether the cpu number is indeed the
123 * current one, and whether rseq is initialized.
125 * The CPU number returned by rseq_cpu_start should always be validated
126 * by passing it to a rseq asm sequence, or by comparing it to the
127 * return value of rseq_current_cpu_raw() if the rseq asm sequence
128 * does not need to be invoked.
130 static inline uint32_t rseq_cpu_start(void)
132 return RSEQ_ACCESS_ONCE(rseq_get_abi()->cpu_id_start);
135 static inline uint32_t rseq_current_cpu(void)
139 cpu = rseq_current_cpu_raw();
140 if (rseq_unlikely(cpu < 0))
141 cpu = rseq_fallback_current_cpu();
145 static inline void rseq_clear_rseq_cs(void)
147 RSEQ_WRITE_ONCE(rseq_get_abi()->rseq_cs.arch.ptr, 0);
151 * rseq_prepare_unload() should be invoked by each thread executing a rseq
152 * critical section at least once between their last critical section and
153 * library unload of the library defining the rseq critical section (struct
154 * rseq_cs) or the code referred to by the struct rseq_cs start_ip and
155 * post_commit_offset fields. This also applies to use of rseq in code
156 * generated by JIT: rseq_prepare_unload() should be invoked at least once by
157 * each thread executing a rseq critical section before reclaim of the memory
158 * holding the struct rseq_cs or reclaim of the code pointed to by struct
159 * rseq_cs start_ip and post_commit_offset fields.
161 static inline void rseq_prepare_unload(void)
163 rseq_clear_rseq_cs();