--- /dev/null
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * Copyright 2011-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Userspace RCU - sys_futex/compat_futex header.
+ */
+
+#ifndef _UST_COMMON_COMPAT_FUTEX_H
+#define _UST_COMMON_COMPAT_FUTEX_H
+
+#include <errno.h>
+#include <stdint.h>
+#include <time.h>
+#include <sys/syscall.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define FUTEX_WAIT 0
+#define FUTEX_WAKE 1
+
+/*
+ * sys_futex compatibility header.
+ * Use *only* *either of* futex_noasync OR futex_async on a given address.
+ *
+ * futex_noasync cannot be executed in signal handlers, but ensures that
+ * it will be put in a wait queue even in compatibility mode.
+ *
+ * futex_async is signal-handler safe for the wakeup. It uses polling
+ * on the wait-side in compatibility mode.
+ *
+ * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted
+ * (returns EINTR).
+ */
+
+int lttng_ust_compat_futex_noasync(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+ __attribute__((visibility("hidden")));
+
+int lttng_ust_compat_futex_async(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+ __attribute__((visibility("hidden")));
+
+#if (defined(__linux__) && defined(__NR_futex))
+
+#include <unistd.h>
+#include <errno.h>
+#include <urcu/compiler.h>
+#include <urcu/arch.h>
+
+static inline int lttng_ust_futex(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+ return syscall(__NR_futex, uaddr, op, val, timeout,
+ uaddr2, val3);
+}
+
+static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+ int ret;
+
+ ret = lttng_ust_futex(uaddr, op, val, timeout, uaddr2, val3);
+ if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
+ /*
+ * The fallback on ENOSYS is the async-safe version of
+ * the compat futex implementation, because the
+ * async-safe compat implementation allows being used
+ * concurrently with calls to futex(). Indeed, sys_futex
+ * FUTEX_WAIT, on some architectures (mips and parisc),
+ * within a given process, spuriously return ENOSYS due
+ * to signal restart bugs on some kernel versions.
+ */
+ return lttng_ust_compat_futex_async(uaddr, op, val, timeout,
+ uaddr2, val3);
+ }
+ return ret;
+
+}
+
+static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+ int ret;
+
+ ret = lttng_ust_futex(uaddr, op, val, timeout, uaddr2, val3);
+ if (caa_unlikely(ret < 0 && errno == ENOSYS)) {
+ return lttng_ust_compat_futex_async(uaddr, op, val, timeout,
+ uaddr2, val3);
+ }
+ return ret;
+}
+
+#elif defined(__FreeBSD__)
+
+#include <sys/types.h>
+#include <sys/umtx.h>
+
+static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout,
+ int32_t *uaddr2 __attribute__((unused)),
+ int32_t val3 __attribute__((unused)))
+{
+ int umtx_op;
+ void *umtx_uaddr = NULL, *umtx_uaddr2 = NULL;
+ struct _umtx_time umtx_timeout = {
+ ._flags = UMTX_ABSTIME,
+ ._clockid = CLOCK_MONOTONIC,
+ };
+
+ switch (op) {
+ case FUTEX_WAIT:
+ /* On FreeBSD, a "u_int" is a 32-bit integer. */
+ umtx_op = UMTX_OP_WAIT_UINT;
+ if (timeout != NULL) {
+ umtx_timeout._timeout = *timeout;
+ umtx_uaddr = (void *) sizeof(umtx_timeout);
+ umtx_uaddr2 = (void *) &umtx_timeout;
+ }
+ break;
+ case FUTEX_WAKE:
+ umtx_op = UMTX_OP_WAKE;
+ break;
+ default:
+ errno = EINVAL;
+ return -1;
+ }
+
+ return _umtx_op(uaddr, umtx_op, (uint32_t) val, umtx_uaddr,
+ umtx_uaddr2);
+}
+
+static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+ return lttng_ust_futex_async(uaddr, op, val, timeout, uaddr2, val3);
+}
+
+#elif defined(__CYGWIN__)
+
+/*
+ * The futex_noasync compat code uses a weak symbol to share state across
+ * different shared object which is not possible on Windows with the
+ * Portable Executable format. Use the async compat code for both cases.
+ */
+static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+ return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
+}
+
+static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+ return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
+}
+
+#else
+
+static inline int lttng_ust_futex_noasync(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+ return lttng_ust_compat_futex_noasync(uaddr, op, val, timeout, uaddr2, val3);
+}
+
+static inline int lttng_ust_futex_async(int32_t *uaddr, int op, int32_t val,
+ const struct timespec *timeout, int32_t *uaddr2, int32_t val3)
+{
+ return lttng_ust_compat_futex_async(uaddr, op, val, timeout, uaddr2, val3);
+}
+
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _UST_COMMON_COMPAT_FUTEX_H */
projects / lttng-ust.git / blobdiff