Implement getcpu override

[lttng-ust.git] / liblttng-ust / lttng-getcpu.c

diff --git a/liblttng-ust/lttng-getcpu.c b/liblttng-ust/lttng-getcpu.c
new file mode 100644 (file)
index 0000000..8f4c0fe
--- /dev/null
+++ b/liblttng-ust/lttng-getcpu.c
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2014  Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; version 2.1 of
+ * the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+#define _GNU_SOURCE
+#include <error.h>
+#include <dlfcn.h>
+#include <stdlib.h>
+#include <usterr-signal-safe.h>
+#include <lttng/ust-getcpu.h>
+#include <urcu/system.h>
+#include <urcu/arch.h>
+
+#include "../libringbuffer/getcpu.h"
+
+int (*lttng_get_cpu)(void);
+
+int lttng_ust_getcpu_override(int (*getcpu)(void))
+{
+       CMM_STORE_SHARED(lttng_get_cpu, getcpu);
+       return 0;
+}
+
+void lttng_ust_getcpu_init(void)
+{
+       const char *libname;
+       void *handle;
+       void (*libinit)(void);
+
+       libname = secure_getenv("LTTNG_UST_GETCPU_PLUGIN");
+       if (!libname)
+               return;
+       handle = dlopen(libname, RTLD_NOW);
+       if (!handle) {
+               PERROR("Cannot load LTTng UST getcpu override library %s",
+                       libname);
+               return;
+       }
+       dlerror();
+       libinit = (void (*)(void)) dlsym(handle,
+               "lttng_ust_getcpu_plugin_init");
+       if (!libinit) {
+               PERROR("Cannot find LTTng UST getcpu override library %s initialization function lttng_ust_getcpu_plugin_init()",
+                       libname);
+               return;
+       }
+       libinit();
+}