--- /dev/null
+/*
+ * rseq.h
+ *
+ * (C) Copyright 2016 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#ifndef RSEQ_H
+#define RSEQ_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <pthread.h>
+#include <signal.h>
+#include <sched.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sched.h>
+#include <linux/rseq.h>
+
+/*
+ * Empty code injection macros, override when testing.
+ * It is important to consider that the ASM injection macros need to be
+ * fully reentrant (e.g. do not modify the stack).
+ */
+#ifndef RSEQ_INJECT_ASM
+#define RSEQ_INJECT_ASM(n)
+#endif
+
+#ifndef RSEQ_INJECT_C
+#define RSEQ_INJECT_C(n)
+#endif
+
+#ifndef RSEQ_INJECT_INPUT
+#define RSEQ_INJECT_INPUT
+#endif
+
+#ifndef RSEQ_INJECT_CLOBBER
+#define RSEQ_INJECT_CLOBBER
+#endif
+
+#ifndef RSEQ_INJECT_FAILED
+#define RSEQ_INJECT_FAILED
+#endif
+
+#ifndef RSEQ_FALLBACK_CNT
+#define RSEQ_FALLBACK_CNT 3
+#endif
+
+uint32_t rseq_get_fallback_wait_cnt(void);
+uint32_t rseq_get_fallback_cnt(void);
+
+extern __thread volatile struct rseq __rseq_abi;
+extern int rseq_has_sys_membarrier;
+
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+#define barrier() __asm__ __volatile__("" : : : "memory")
+
+#define ACCESS_ONCE(x) (*(__volatile__ __typeof__(x) *)&(x))
+#define WRITE_ONCE(x, v) __extension__ ({ ACCESS_ONCE(x) = (v); })
+#define READ_ONCE(x) ACCESS_ONCE(x)
+
+#if defined(__x86_64__) || defined(__i386__)
+#include <rseq-x86.h>
+#elif defined(__ARMEL__)
+#include <rseq-arm.h>
+#elif defined(__PPC__)
+#include <rseq-ppc.h>
+#else
+#error unsupported target
+#endif
+
+enum rseq_lock_state {
+ RSEQ_LOCK_STATE_RESTART = 0,
+ RSEQ_LOCK_STATE_LOCK = 1,
+ RSEQ_LOCK_STATE_FAIL = 2,
+};
+
+struct rseq_lock {
+ pthread_mutex_t lock;
+ int32_t state; /* enum rseq_lock_state */
+};
+
+/* State returned by rseq_start, passed as argument to rseq_finish. */
+struct rseq_state {
+ volatile struct rseq *rseqp;
+ int32_t cpu_id; /* cpu_id at start. */
+ uint32_t event_counter; /* event_counter at start. */
+ int32_t lock_state; /* Lock state at start. */
+};
+
+/*
+ * Register rseq for the current thread. This needs to be called once
+ * by any thread which uses restartable sequences, before they start
+ * using restartable sequences. If initialization is not invoked, or if
+ * it fails, the restartable critical sections will fall-back on locking
+ * (rseq_lock).
+ */
+int rseq_register_current_thread(void);
+
+/*
+ * Unregister rseq for current thread.
+ */
+int rseq_unregister_current_thread(void);
+
+/*
+ * The fallback lock should be initialized before being used by any
+ * thread, and destroyed after all threads are done using it. This lock
+ * should be used by all rseq calls associated with shared data, either
+ * between threads, or between processes in a shared memory.
+ *
+ * There may be many rseq_lock per process, e.g. one per protected data
+ * structure.
+ */
+int rseq_init_lock(struct rseq_lock *rlock);
+int rseq_destroy_lock(struct rseq_lock *rlock);
+
+/*
+ * Restartable sequence fallback prototypes. Fallback on locking when
+ * rseq is not initialized, not available on the system, or during
+ * single-stepping to ensure forward progress.
+ */
+int rseq_fallback_begin(struct rseq_lock *rlock);
+void rseq_fallback_end(struct rseq_lock *rlock, int cpu);
+void rseq_fallback_wait(struct rseq_lock *rlock);
+void rseq_fallback_noinit(struct rseq_state *rseq_state);
+
+/*
+ * Restartable sequence fallback for reading the current CPU number.
+ */
+int rseq_fallback_current_cpu(void);
+
+static inline int32_t rseq_cpu_at_start(struct rseq_state start_value)
+{
+ return start_value.cpu_id;
+}
+
+static inline int32_t rseq_current_cpu_raw(void)
+{
+ return ACCESS_ONCE(__rseq_abi.u.e.cpu_id);
+}
+
+static inline int32_t rseq_current_cpu(void)
+{
+ int32_t cpu;
+
+ cpu = rseq_current_cpu_raw();
+ if (unlikely(cpu < 0))
+ cpu = rseq_fallback_current_cpu();
+ return cpu;
+}
+
+static inline __attribute__((always_inline))
+struct rseq_state rseq_start(struct rseq_lock *rlock)
+{
+ struct rseq_state result;
+
+ result.rseqp = &__rseq_abi;
+ if (has_single_copy_load_64()) {
+ union rseq_cpu_event u;
+
+ u.v = ACCESS_ONCE(result.rseqp->u.v);
+ result.event_counter = u.e.event_counter;
+ result.cpu_id = u.e.cpu_id;
+ } else {
+ result.event_counter =
+ ACCESS_ONCE(result.rseqp->u.e.event_counter);
+ /* load event_counter before cpu_id. */
+ RSEQ_INJECT_C(6)
+ result.cpu_id = ACCESS_ONCE(result.rseqp->u.e.cpu_id);
+ }
+ /*
+ * Read event counter before lock state and cpu_id. This ensures
+ * that when the state changes from RESTART to LOCK, if we have
+ * some threads that have already seen the RESTART still in
+ * flight, they will necessarily be preempted/signalled before a
+ * thread can see the LOCK state for that same CPU. That
+ * preemption/signalling will cause them to restart, so they
+ * don't interfere with the lock.
+ */
+ RSEQ_INJECT_C(7)
+
+ if (!has_fast_acquire_release() && likely(rseq_has_sys_membarrier)) {
+ result.lock_state = ACCESS_ONCE(rlock->state);
+ barrier();
+ } else {
+ /*
+ * Load lock state with acquire semantic. Matches
+ * smp_store_release() in rseq_fallback_end().
+ */
+ result.lock_state = smp_load_acquire(&rlock->state);
+ }
+ if (unlikely(result.cpu_id < 0))
+ rseq_fallback_noinit(&result);
+ /*
+ * Ensure the compiler does not re-order loads of protected
+ * values before we load the event counter.
+ */
+ barrier();
+ return result;
+}
+
+enum rseq_finish_type {
+ RSEQ_FINISH_SINGLE,
+ RSEQ_FINISH_TWO,
+ RSEQ_FINISH_MEMCPY,
+};
+
+/*
+ * p_spec and to_write_spec are used for a speculative write attempted
+ * near the end of the restartable sequence. A rseq_finish2 may fail
+ * even after this write takes place.
+ *
+ * p_final and to_write_final are used for the final write. If this
+ * write takes place, the rseq_finish2 is guaranteed to succeed.
+ */
+static inline __attribute__((always_inline))
+bool __rseq_finish(struct rseq_lock *rlock,
+ intptr_t *p_spec, intptr_t to_write_spec,
+ void *p_memcpy, void *to_write_memcpy, size_t len_memcpy,
+ intptr_t *p_final, intptr_t to_write_final,
+ struct rseq_state start_value,
+ enum rseq_finish_type type, bool release)
+{
+ RSEQ_INJECT_C(9)
+
+ if (unlikely(start_value.lock_state != RSEQ_LOCK_STATE_RESTART)) {
+ if (start_value.lock_state == RSEQ_LOCK_STATE_LOCK)
+ rseq_fallback_wait(rlock);
+ return false;
+ }
+ switch (type) {
+ case RSEQ_FINISH_SINGLE:
+ RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure,
+ /* no speculative write */, /* no speculative write */,
+ RSEQ_FINISH_FINAL_STORE_ASM(),
+ RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final),
+ /* no extra clobber */, /* no arg */, /* no arg */,
+ /* no arg */
+ );
+ break;
+ case RSEQ_FINISH_TWO:
+ if (release) {
+ RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure,
+ RSEQ_FINISH_SPECULATIVE_STORE_ASM(),
+ RSEQ_FINISH_SPECULATIVE_STORE_INPUT(p_spec, to_write_spec),
+ RSEQ_FINISH_FINAL_STORE_RELEASE_ASM(),
+ RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final),
+ /* no extra clobber */, /* no arg */, /* no arg */,
+ /* no arg */
+ );
+ } else {
+ RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure,
+ RSEQ_FINISH_SPECULATIVE_STORE_ASM(),
+ RSEQ_FINISH_SPECULATIVE_STORE_INPUT(p_spec, to_write_spec),
+ RSEQ_FINISH_FINAL_STORE_ASM(),
+ RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final),
+ /* no extra clobber */, /* no arg */, /* no arg */,
+ /* no arg */
+ );
+ }
+ break;
+ case RSEQ_FINISH_MEMCPY:
+ if (release) {
+ RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure,
+ RSEQ_FINISH_MEMCPY_STORE_ASM(),
+ RSEQ_FINISH_MEMCPY_STORE_INPUT(p_memcpy, to_write_memcpy, len_memcpy),
+ RSEQ_FINISH_FINAL_STORE_RELEASE_ASM(),
+ RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final),
+ RSEQ_FINISH_MEMCPY_CLOBBER(),
+ RSEQ_FINISH_MEMCPY_SETUP(),
+ RSEQ_FINISH_MEMCPY_TEARDOWN(),
+ RSEQ_FINISH_MEMCPY_SCRATCH()
+ );
+ } else {
+ RSEQ_FINISH_ASM(p_final, to_write_final, start_value, failure,
+ RSEQ_FINISH_MEMCPY_STORE_ASM(),
+ RSEQ_FINISH_MEMCPY_STORE_INPUT(p_memcpy, to_write_memcpy, len_memcpy),
+ RSEQ_FINISH_FINAL_STORE_ASM(),
+ RSEQ_FINISH_FINAL_STORE_INPUT(p_final, to_write_final),
+ RSEQ_FINISH_MEMCPY_CLOBBER(),
+ RSEQ_FINISH_MEMCPY_SETUP(),
+ RSEQ_FINISH_MEMCPY_TEARDOWN(),
+ RSEQ_FINISH_MEMCPY_SCRATCH()
+ );
+ }
+ break;
+ }
+ return true;
+failure:
+ RSEQ_INJECT_FAILED
+ return false;
+}
+
+static inline __attribute__((always_inline))
+bool rseq_finish(struct rseq_lock *rlock,
+ intptr_t *p, intptr_t to_write,
+ struct rseq_state start_value)
+{
+ return __rseq_finish(rlock, NULL, 0,
+ NULL, NULL, 0,
+ p, to_write, start_value,
+ RSEQ_FINISH_SINGLE, false);
+}
+
+static inline __attribute__((always_inline))
+bool rseq_finish2(struct rseq_lock *rlock,
+ intptr_t *p_spec, intptr_t to_write_spec,
+ intptr_t *p_final, intptr_t to_write_final,
+ struct rseq_state start_value)
+{
+ return __rseq_finish(rlock, p_spec, to_write_spec,
+ NULL, NULL, 0,
+ p_final, to_write_final, start_value,
+ RSEQ_FINISH_TWO, false);
+}
+
+static inline __attribute__((always_inline))
+bool rseq_finish2_release(struct rseq_lock *rlock,
+ intptr_t *p_spec, intptr_t to_write_spec,
+ intptr_t *p_final, intptr_t to_write_final,
+ struct rseq_state start_value)
+{
+ return __rseq_finish(rlock, p_spec, to_write_spec,
+ NULL, NULL, 0,
+ p_final, to_write_final, start_value,
+ RSEQ_FINISH_TWO, true);
+}
+
+static inline __attribute__((always_inline))
+bool rseq_finish_memcpy(struct rseq_lock *rlock,
+ void *p_memcpy, void *to_write_memcpy, size_t len_memcpy,
+ intptr_t *p_final, intptr_t to_write_final,
+ struct rseq_state start_value)
+{
+ return __rseq_finish(rlock, NULL, 0,
+ p_memcpy, to_write_memcpy, len_memcpy,
+ p_final, to_write_final, start_value,
+ RSEQ_FINISH_MEMCPY, false);
+}
+
+static inline __attribute__((always_inline))
+bool rseq_finish_memcpy_release(struct rseq_lock *rlock,
+ void *p_memcpy, void *to_write_memcpy, size_t len_memcpy,
+ intptr_t *p_final, intptr_t to_write_final,
+ struct rseq_state start_value)
+{
+ return __rseq_finish(rlock, NULL, 0,
+ p_memcpy, to_write_memcpy, len_memcpy,
+ p_final, to_write_final, start_value,
+ RSEQ_FINISH_MEMCPY, true);
+}
+
+#define __rseq_store_RSEQ_FINISH_SINGLE(_targetptr_spec, _newval_spec, \
+ _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final) \
+ do { \
+ *(_targetptr_final) = (_newval_final); \
+ } while (0)
+
+#define __rseq_store_RSEQ_FINISH_TWO(_targetptr_spec, _newval_spec, \
+ _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final) \
+ do { \
+ *(_targetptr_spec) = (_newval_spec); \
+ *(_targetptr_final) = (_newval_final); \
+ } while (0)
+
+#define __rseq_store_RSEQ_FINISH_MEMCPY(_targetptr_spec, \
+ _newval_spec, _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final) \
+ do { \
+ memcpy(_dest_memcpy, _src_memcpy, _len_memcpy); \
+ *(_targetptr_final) = (_newval_final); \
+ } while (0)
+
+/*
+ * Helper macro doing two restartable critical section attempts, and if
+ * they fail, fallback on locking.
+ */
+#define __do_rseq(_type, _lock, _rseq_state, _cpu, _result, \
+ _targetptr_spec, _newval_spec, \
+ _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final, _code, _release) \
+ do { \
+ _rseq_state = rseq_start(_lock); \
+ _cpu = rseq_cpu_at_start(_rseq_state); \
+ _result = true; \
+ _code \
+ if (unlikely(!_result)) \
+ break; \
+ if (likely(__rseq_finish(_lock, \
+ _targetptr_spec, _newval_spec, \
+ _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final, \
+ _rseq_state, _type, _release))) \
+ break; \
+ _rseq_state = rseq_start(_lock); \
+ _cpu = rseq_cpu_at_start(_rseq_state); \
+ _result = true; \
+ _code \
+ if (unlikely(!_result)) \
+ break; \
+ if (likely(__rseq_finish(_lock, \
+ _targetptr_spec, _newval_spec, \
+ _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final, \
+ _rseq_state, _type, _release))) \
+ break; \
+ _cpu = rseq_fallback_begin(_lock); \
+ _result = true; \
+ _code \
+ if (likely(_result)) \
+ __rseq_store_##_type(_targetptr_spec, \
+ _newval_spec, _dest_memcpy, \
+ _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final); \
+ rseq_fallback_end(_lock, _cpu); \
+ } while (0)
+
+#define do_rseq(_lock, _rseq_state, _cpu, _result, _targetptr, _newval, \
+ _code) \
+ __do_rseq(RSEQ_FINISH_SINGLE, _lock, _rseq_state, _cpu, _result,\
+ NULL, 0, NULL, NULL, 0, _targetptr, _newval, _code, false)
+
+#define do_rseq2(_lock, _rseq_state, _cpu, _result, \
+ _targetptr_spec, _newval_spec, \
+ _targetptr_final, _newval_final, _code) \
+ __do_rseq(RSEQ_FINISH_TWO, _lock, _rseq_state, _cpu, _result, \
+ _targetptr_spec, _newval_spec, \
+ NULL, NULL, 0, \
+ _targetptr_final, _newval_final, _code, false)
+
+#define do_rseq2_release(_lock, _rseq_state, _cpu, _result, \
+ _targetptr_spec, _newval_spec, \
+ _targetptr_final, _newval_final, _code) \
+ __do_rseq(RSEQ_FINISH_TWO, _lock, _rseq_state, _cpu, _result, \
+ _targetptr_spec, _newval_spec, \
+ NULL, NULL, 0, \
+ _targetptr_final, _newval_final, _code, true)
+
+#define do_rseq_memcpy(_lock, _rseq_state, _cpu, _result, \
+ _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final, _code) \
+ __do_rseq(RSEQ_FINISH_MEMCPY, _lock, _rseq_state, _cpu, _result,\
+ NULL, 0, \
+ _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final, _code, false)
+
+#define do_rseq_memcpy_release(_lock, _rseq_state, _cpu, _result, \
+ _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final, _code) \
+ __do_rseq(RSEQ_FINISH_MEMCPY, _lock, _rseq_state, _cpu, _result,\
+ NULL, 0, \
+ _dest_memcpy, _src_memcpy, _len_memcpy, \
+ _targetptr_final, _newval_final, _code, true)
+
+#endif /* RSEQ_H_ */
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