ust: add tracepoint.{c,h} from kernel
[ust.git] / libmarkers / tracepoint.h
diff --git a/libmarkers/tracepoint.h b/libmarkers/tracepoint.h
new file mode 100644 (file)
index 0000000..860b674
--- /dev/null
@@ -0,0 +1,177 @@
+#ifndef _LINUX_TRACEPOINT_H
+#define _LINUX_TRACEPOINT_H
+
+/*
+ * Kernel Tracepoint API.
+ *
+ * See Documentation/tracepoint.txt.
+ *
+ * (C) Copyright 2008 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ *
+ * Heavily inspired from the Linux Kernel Markers.
+ *
+ * This file is released under the GPLv2.
+ * See the file COPYING for more details.
+ */
+
+#include <linux/immediate.h>
+#include <linux/types.h>
+#include <linux/rcupdate.h>
+
+struct module;
+struct tracepoint;
+
+struct tracepoint {
+       const char *name;               /* Tracepoint name */
+       DEFINE_IMV(char, state);        /* State. */
+       void **funcs;
+} __attribute__((aligned(32)));                /*
+                                        * Aligned on 32 bytes because it is
+                                        * globally visible and gcc happily
+                                        * align these on the structure size.
+                                        * Keep in sync with vmlinux.lds.h.
+                                        */
+
+#define TPPROTO(args...)       args
+#define TPARGS(args...)                args
+
+#ifdef CONFIG_TRACEPOINTS
+
+/*
+ * it_func[0] is never NULL because there is at least one element in the array
+ * when the array itself is non NULL.
+ */
+#define __DO_TRACE(tp, proto, args)                                    \
+       do {                                                            \
+               void **it_func;                                         \
+                                                                       \
+               rcu_read_lock_sched_notrace();                          \
+               it_func = rcu_dereference((tp)->funcs);                 \
+               if (it_func) {                                          \
+                       do {                                            \
+                               ((void(*)(proto))(*it_func))(args);     \
+                       } while (*(++it_func));                         \
+               }                                                       \
+               rcu_read_unlock_sched_notrace();                        \
+       } while (0)
+
+#define __CHECK_TRACE(name, generic, proto, args)                      \
+       do {                                                            \
+               if (!generic) {                                         \
+                       if (unlikely(imv_read(__tracepoint_##name.state))) \
+                               __DO_TRACE(&__tracepoint_##name,        \
+                                       TPPROTO(proto), TPARGS(args));  \
+               } else {                                                \
+                       if (unlikely(_imv_read(__tracepoint_##name.state))) \
+                               __DO_TRACE(&__tracepoint_##name,        \
+                                       TPPROTO(proto), TPARGS(args));  \
+               }                                                       \
+       } while (0)
+
+/*
+ * Make sure the alignment of the structure in the __tracepoints section will
+ * not add unwanted padding between the beginning of the section and the
+ * structure. Force alignment to the same alignment as the section start.
+ *
+ * The "generic" argument, passed to the declared __trace_##name inline
+ * function controls which tracepoint enabling mechanism must be used.
+ * If generic is true, a variable read is used.
+ * If generic is false, immediate values are used.
+ */
+#define DECLARE_TRACE(name, proto, args)                               \
+       extern struct tracepoint __tracepoint_##name;                   \
+       static inline void trace_##name(proto)                          \
+       {                                                               \
+               __CHECK_TRACE(name, 0, TPPROTO(proto), TPARGS(args));   \
+       }                                                               \
+       static inline void _trace_##name(proto)                         \
+       {                                                               \
+               __CHECK_TRACE(name, 1, TPPROTO(proto), TPARGS(args));   \
+       }                                                               \
+       static inline int register_trace_##name(void (*probe)(proto))   \
+       {                                                               \
+               return tracepoint_probe_register(#name, (void *)probe); \
+       }                                                               \
+       static inline int unregister_trace_##name(void (*probe)(proto)) \
+       {                                                               \
+               return tracepoint_probe_unregister(#name, (void *)probe);\
+       }
+
+#define DEFINE_TRACE(name)                                             \
+       static const char __tpstrtab_##name[]                           \
+       __attribute__((section("__tracepoints_strings"))) = #name;      \
+       struct tracepoint __tracepoint_##name                           \
+       __attribute__((section("__tracepoints"), aligned(32))) =        \
+               { __tpstrtab_##name, 0, NULL }
+
+#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)                             \
+       EXPORT_SYMBOL_GPL(__tracepoint_##name)
+#define EXPORT_TRACEPOINT_SYMBOL(name)                                 \
+       EXPORT_SYMBOL(__tracepoint_##name)
+
+extern void tracepoint_update_probe_range(struct tracepoint *begin,
+       struct tracepoint *end);
+
+#else /* !CONFIG_TRACEPOINTS */
+#define DECLARE_TRACE(name, proto, args)                               \
+       static inline void trace_##name(proto)                          \
+       { }                                                             \
+       static inline void _trace_##name(proto)                         \
+       { }                                                             \
+       static inline int register_trace_##name(void (*probe)(proto))   \
+       {                                                               \
+               return -ENOSYS;                                         \
+       }                                                               \
+       static inline int unregister_trace_##name(void (*probe)(proto)) \
+       {                                                               \
+               return -ENOSYS;                                         \
+       }
+
+#define DEFINE_TRACE(name)
+#define EXPORT_TRACEPOINT_SYMBOL_GPL(name)
+#define EXPORT_TRACEPOINT_SYMBOL(name)
+
+static inline void tracepoint_update_probe_range(struct tracepoint *begin,
+       struct tracepoint *end)
+{ }
+#endif /* CONFIG_TRACEPOINTS */
+
+/*
+ * Connect a probe to a tracepoint.
+ * Internal API, should not be used directly.
+ */
+extern int tracepoint_probe_register(const char *name, void *probe);
+
+/*
+ * Disconnect a probe from a tracepoint.
+ * Internal API, should not be used directly.
+ */
+extern int tracepoint_probe_unregister(const char *name, void *probe);
+
+extern int tracepoint_probe_register_noupdate(const char *name, void *probe);
+extern int tracepoint_probe_unregister_noupdate(const char *name, void *probe);
+extern void tracepoint_probe_update_all(void);
+
+struct tracepoint_iter {
+       struct module *module;
+       struct tracepoint *tracepoint;
+};
+
+extern void tracepoint_iter_start(struct tracepoint_iter *iter);
+extern void tracepoint_iter_next(struct tracepoint_iter *iter);
+extern void tracepoint_iter_stop(struct tracepoint_iter *iter);
+extern void tracepoint_iter_reset(struct tracepoint_iter *iter);
+extern int tracepoint_get_iter_range(struct tracepoint **tracepoint,
+       struct tracepoint *begin, struct tracepoint *end);
+
+/*
+ * tracepoint_synchronize_unregister must be called between the last tracepoint
+ * probe unregistration and the end of module exit to make sure there is no
+ * caller executing a probe when it is freed.
+ */
+static inline void tracepoint_synchronize_unregister(void)
+{
+       synchronize_sched();
+}
+
+#endif
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