From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Fri, 23 Apr 2021 16:25:53 +0000 (-0400)
Subject: tracepoint: introduce macros to hide tracepoint/provider symbols
X-Git-Tag: v2.13.0-rc1~19
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=29d6f42146cb632bd8c8cee3d087aefc0f84dd91;p=lttng-ust.git

tracepoint: introduce macros to hide tracepoint/provider symbols

Introduce the following macros:

LTTNG_UST_TRACEPOINT_HIDDEN_DEFINITION: Hide symbols associated with
tracepoint module instrumentation.

LTTNG_UST_TRACEPOINT_PROVIDER_HIDDEN_DEFINITION: Hide symbols associated
with tracepoint provider.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: I493c325b73c16044dcc117b48cc91df3b05f18b0
---

diff --git a/include/lttng/tracepoint.h b/include/lttng/tracepoint.h
index be18e94c..23f01547 100644
--- a/include/lttng/tracepoint.h
+++ b/include/lttng/tracepoint.h
@@ -182,7 +182,8 @@ extern "C" {
  * address.
  */
 #define LTTNG_UST__DECLARE_TRACEPOINT(_provider, _name, ...)			 		\
-extern struct lttng_ust_tracepoint lttng_ust_tracepoint_##_provider##___##_name;		\
+extern struct lttng_ust_tracepoint lttng_ust_tracepoint_##_provider##___##_name		\
+		LTTNG_UST__TRACEPOINT_DEFINITION_VISIBILITY;				\
 static inline										\
 void lttng_ust_tracepoint_cb_##_provider##___##_name(LTTNG_UST__TP_ARGS_PROTO(__VA_ARGS__))		\
 	__attribute__((always_inline, unused)) lttng_ust_notrace;			\
@@ -482,7 +483,8 @@ extern struct lttng_ust_tracepoint * const __stop_lttng_ust_tracepoints_ptrs[]
 
 #define LTTNG_UST__DEFINE_TRACEPOINT(_provider, _name, _args)				\
 	lttng_ust_tracepoint_validate_name_len(_provider, _name);		\
-	extern int lttng_ust_tracepoint_provider_##_provider; 				\
+	extern int lttng_ust_tracepoint_provider_##_provider			\
+		LTTNG_UST__TRACEPOINT_PROVIDER_DEFINITION_VISIBILITY;		\
 	static const char lttng_ust_tp_provider_strtab_##_provider##___##_name[]	\
 		__attribute__((section("lttng_ust_tracepoints_strings"))) =		\
 			#_provider;						\
@@ -490,7 +492,8 @@ extern struct lttng_ust_tracepoint * const __stop_lttng_ust_tracepoints_ptrs[]
 		__attribute__((section("lttng_ust_tracepoints_strings"))) =		\
 			#_name;							\
 	struct lttng_ust_tracepoint lttng_ust_tracepoint_##_provider##___##_name	\
-		__attribute__((section("lttng_ust_tracepoints"))) = {			\
+		__attribute__((section("lttng_ust_tracepoints")))		\
+		LTTNG_UST__TRACEPOINT_DEFINITION_VISIBILITY = {			\
 			sizeof(struct lttng_ust_tracepoint),			\
 			lttng_ust_tp_provider_strtab_##_provider##___##_name,		\
 			lttng_ust_tp_name_strtab_##_provider##___##_name,		\
@@ -596,6 +599,39 @@ lttng_ust__tracepoints__ptrs_destroy(void)
 
 /* The following declarations must be outside re-inclusion protection. */
 
+/*
+ * LTTNG_UST_TRACEPOINT_HIDDEN_DEFINITION: Define this before including
+ * a tracepoint instrumentation header to hide symbols associated with
+ * tracepoint module instrumentation. This is useful if all compile
+ * units using the lttng_ust_tracepoint(),
+ * lttng_ust_tracepoint_enabled() and lttng_ust_do_tracepoint() macros
+ * is within the same module as the compile unit including the
+ * tracepoint header after defining LTTNG_UST_TRACEPOINT_DEFINE.
+ */
+
+#undef LTTNG_UST__TRACEPOINT_DEFINITION_VISIBILITY
+#ifdef LTTNG_UST_TRACEPOINT_HIDDEN_DEFINITION
+#define LTTNG_UST__TRACEPOINT_DEFINITION_VISIBILITY		__attribute__((visibility("hidden")))
+#else
+#define LTTNG_UST__TRACEPOINT_DEFINITION_VISIBILITY		__attribute__((visibility("default")))
+#endif
+
+/*
+ * LTTNG_UST_TRACEPOINT_PROVIDER_HIDDEN_DEFINITION: Define this before
+ * including a tracepoint instrumentation header to hide symbols
+ * associated with the tracepoint provider. This is useful if the
+ * tracepoint definition (including the header after defining
+ * LTTNG_UST_TRACEPOINT_DEFINE) is in the same module as the provider
+ * (including the header after defining
+ * LTTNG_UST_TRACEPOINT_CREATE_PROBES).
+ */
+#undef LTTNG_UST__TRACEPOINT_PROVIDER_DEFINITION_VISIBILITY
+#ifdef LTTNG_UST_TRACEPOINT_PROVIDER_HIDDEN_DEFINITION
+#define LTTNG_UST__TRACEPOINT_PROVIDER_DEFINITION_VISIBILITY	__attribute__((visibility("hidden")))
+#else
+#define LTTNG_UST__TRACEPOINT_PROVIDER_DEFINITION_VISIBILITY	__attribute__((visibility("default")))
+#endif
+
 #ifndef LTTNG_UST_TRACEPOINT_ENUM
 
 /*
diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h
index 10ff52b0..654b367f 100644
--- a/include/lttng/ust-tracepoint-event.h
+++ b/include/lttng/ust-tracepoint-event.h
@@ -1211,5 +1211,21 @@ LTTNG_UST__TP_COMBINE_TOKENS(lttng_ust__events_exit__, LTTNG_UST_TRACEPOINT_PROV
 	LTTNG_UST__TP_COMBINE_TOKENS(lttng_ust__probe_register_cookie___, LTTNG_UST_TRACEPOINT_PROVIDER) = NULL;
 }
 
+/*
+ * LTTNG_UST_TRACEPOINT_PROVIDER_HIDDEN_DEFINITION: Define this before
+ * including a tracepoint instrumentation header to hide symbols
+ * associated with the tracepoint provider. This is useful if the
+ * tracepoint definition (including the header after defining
+ * LTTNG_UST_TRACEPOINT_DEFINE) is in the same module as the provider
+ * (including the header after defining
+ * LTTNG_UST_TRACEPOINT_CREATE_PROBES).
+ */
+#undef LTTNG_UST__TRACEPOINT_PROVIDER_DEFINITION_VISIBILITY
+#ifdef LTTNG_UST_TRACEPOINT_PROVIDER_HIDDEN_DEFINITION
+#define LTTNG_UST__TRACEPOINT_PROVIDER_DEFINITION_VISIBILITY	__attribute__((visibility("hidden")))
+#else
+#define LTTNG_UST__TRACEPOINT_PROVIDER_DEFINITION_VISIBILITY	__attribute__((visibility("default")))
+#endif
+
 int LTTNG_UST__TP_COMBINE_TOKENS(lttng_ust_tracepoint_provider_, LTTNG_UST_TRACEPOINT_PROVIDER)
-	__attribute__((visibility("default")));
+	LTTNG_UST__TRACEPOINT_PROVIDER_DEFINITION_VISIBILITY;