--- /dev/null
+/*
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ * Copyright (C) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ */
+
+#define _LGPL_SOURCE
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include <lttng/ust-clock.h>
+#include <lttng/ust-events.h>
+#include <urcu/system.h>
+#include <urcu/arch.h>
+
+#include "common/logging.h"
+#include "common/getenv.h"
+
+#include "lib/lttng-ust-common/clock.h"
+
+struct lttng_ust_trace_clock *lttng_ust_trace_clock;
+
+static
+struct lttng_ust_trace_clock user_tc;
+
+static
+void *clock_handle;
+
+static
+uint64_t trace_clock_freq_monotonic(void)
+{
+ return 1000000000ULL;
+}
+
+static
+int trace_clock_uuid_monotonic(char *uuid)
+{
+ int ret = 0;
+ size_t len;
+ FILE *fp;
+
+ /*
+ * boot_id needs to be read once before being used concurrently
+ * to deal with a Linux kernel race. A fix is proposed for
+ * upstream, but the work-around is needed for older kernels.
+ */
+ fp = fopen("/proc/sys/kernel/random/boot_id", "r");
+ if (!fp) {
+ return -ENOENT;
+ }
+ len = fread(uuid, 1, LTTNG_UST_UUID_STR_LEN - 1, fp);
+ if (len < LTTNG_UST_UUID_STR_LEN - 1) {
+ ret = -EINVAL;
+ goto end;
+ }
+ uuid[LTTNG_UST_UUID_STR_LEN - 1] = '\0';
+end:
+ fclose(fp);
+ return ret;
+}
+
+static
+const char *trace_clock_name_monotonic(void)
+{
+ return "monotonic";
+}
+
+static
+const char *trace_clock_description_monotonic(void)
+{
+ return "Monotonic Clock";
+}
+
+int lttng_ust_trace_clock_set_read64_cb(lttng_ust_clock_read64_function read64_cb)
+{
+ if (CMM_LOAD_SHARED(lttng_ust_trace_clock))
+ return -EBUSY;
+ user_tc.read64 = read64_cb;
+ return 0;
+}
+
+int lttng_ust_trace_clock_get_read64_cb(lttng_ust_clock_read64_function *read64_cb)
+{
+ struct lttng_ust_trace_clock *ltc = CMM_LOAD_SHARED(lttng_ust_trace_clock);
+
+ if (caa_likely(!ltc)) {
+ *read64_cb = &trace_clock_read64_monotonic;
+ } else {
+ cmm_read_barrier_depends(); /* load ltc before content */
+ *read64_cb = ltc->read64;
+ }
+ return 0;
+}
+
+int lttng_ust_trace_clock_set_freq_cb(lttng_ust_clock_freq_function freq_cb)
+{
+ if (CMM_LOAD_SHARED(lttng_ust_trace_clock))
+ return -EBUSY;
+ user_tc.freq = freq_cb;
+ return 0;
+}
+
+int lttng_ust_trace_clock_get_freq_cb(lttng_ust_clock_freq_function *freq_cb)
+{
+ struct lttng_ust_trace_clock *ltc = CMM_LOAD_SHARED(lttng_ust_trace_clock);
+
+ if (caa_likely(!ltc)) {
+ *freq_cb = &trace_clock_freq_monotonic;
+ } else {
+ cmm_read_barrier_depends(); /* load ltc before content */
+ *freq_cb = ltc->freq;
+ }
+ return 0;
+}
+
+int lttng_ust_trace_clock_set_uuid_cb(lttng_ust_clock_uuid_function uuid_cb)
+{
+ if (CMM_LOAD_SHARED(lttng_ust_trace_clock))
+ return -EBUSY;
+ user_tc.uuid = uuid_cb;
+ return 0;
+}
+
+int lttng_ust_trace_clock_get_uuid_cb(lttng_ust_clock_uuid_function *uuid_cb)
+{
+ struct lttng_ust_trace_clock *ltc = CMM_LOAD_SHARED(lttng_ust_trace_clock);
+
+ if (caa_likely(!ltc)) {
+ *uuid_cb = &trace_clock_uuid_monotonic;
+ } else {
+ cmm_read_barrier_depends(); /* load ltc before content */
+ *uuid_cb = ltc->uuid;
+ }
+ return 0;
+}
+
+int lttng_ust_trace_clock_set_name_cb(lttng_ust_clock_name_function name_cb)
+{
+ if (CMM_LOAD_SHARED(lttng_ust_trace_clock))
+ return -EBUSY;
+ user_tc.name = name_cb;
+ return 0;
+}
+
+int lttng_ust_trace_clock_get_name_cb(lttng_ust_clock_name_function *name_cb)
+{
+ struct lttng_ust_trace_clock *ltc = CMM_LOAD_SHARED(lttng_ust_trace_clock);
+
+ if (caa_likely(!ltc)) {
+ *name_cb = &trace_clock_name_monotonic;
+ } else {
+ cmm_read_barrier_depends(); /* load ltc before content */
+ *name_cb = ltc->name;
+ }
+ return 0;
+}
+
+int lttng_ust_trace_clock_set_description_cb(lttng_ust_clock_description_function description_cb)
+{
+ if (CMM_LOAD_SHARED(lttng_ust_trace_clock))
+ return -EBUSY;
+ user_tc.description = description_cb;
+ return 0;
+}
+
+int lttng_ust_trace_clock_get_description_cb(lttng_ust_clock_description_function *description_cb)
+{
+ struct lttng_ust_trace_clock *ltc = CMM_LOAD_SHARED(lttng_ust_trace_clock);
+
+ if (caa_likely(!ltc)) {
+ *description_cb = &trace_clock_description_monotonic;
+ } else {
+ cmm_read_barrier_depends(); /* load ltc before content */
+ *description_cb = ltc->description;
+ }
+ return 0;
+}
+
+int lttng_ust_enable_trace_clock_override(void)
+{
+ if (CMM_LOAD_SHARED(lttng_ust_trace_clock))
+ return -EBUSY;
+ if (!user_tc.read64)
+ return -EINVAL;
+ if (!user_tc.freq)
+ return -EINVAL;
+ if (!user_tc.name)
+ return -EINVAL;
+ if (!user_tc.description)
+ return -EINVAL;
+ /* Use default uuid cb when NULL */
+ cmm_smp_mb(); /* Store callbacks before trace clock */
+ CMM_STORE_SHARED(lttng_ust_trace_clock, &user_tc);
+ return 0;
+}
+
+void lttng_ust_clock_init(void)
+{
+ const char *libname;
+ void (*libinit)(void);
+
+ if (clock_handle)
+ return;
+ libname = lttng_ust_getenv("LTTNG_UST_CLOCK_PLUGIN");
+ if (!libname)
+ return;
+ clock_handle = dlopen(libname, RTLD_NOW);
+ if (!clock_handle) {
+ PERROR("Cannot load LTTng UST clock override library %s",
+ libname);
+ return;
+ }
+ dlerror();
+ libinit = (void (*)(void)) dlsym(clock_handle,
+ "lttng_ust_clock_plugin_init");
+ if (!libinit) {
+ PERROR("Cannot find LTTng UST clock override library %s initialization function lttng_ust_clock_plugin_init()",
+ libname);
+ return;
+ }
+ libinit();
+}
projects / lttng-ust.git / blobdiff