trace: Add LTTng-UST interface support

No probes at this point. They are per subsystem and thus in later commits.

Part of #32910

configure.ac

@@ -258,6 +258,24 @@ AC_ARG_ENABLE(libscrypt,
 
 dnl --- Tracing Options. ---
 
+TOR_TRACE_LIBS=
+
+dnl LTTng instrumentation option.
+AC_ARG_ENABLE(tracing-instrumentation-lttng,
+              AS_HELP_STRING([--enable-tracing-instrumentation-lttng],
+                             [build with LTTng-UST instrumentation]))
+AM_CONDITIONAL([USE_TRACING_INSTRUMENTATION_LTTNG],
+               [test "x$enable_tracing_instrumentation_lttng" = "xyes"])
+
+if test "x$enable_tracing_instrumentation_lttng" = "xyes"; then
+  AC_CHECK_HEADERS([lttng/tracepoint.h], [],
+                   [AC_MSG_ERROR([LTTng instrumentation headers not found.
+                                  On Debian, apt install liblttng-ust-dev"])], [])
+  AC_DEFINE([USE_TRACING_INSTRUMENTATION_LTTNG], [1], [Using LTTng instrumentation])
+  TOR_TRACE_LIBS="-llttng-ust -ldl"
+fi
+
+
 dnl USDT instrumentation option.
 AC_ARG_ENABLE(tracing-instrumentation-usdt,
               AS_HELP_STRING([--enable-tracing-instrumentation-usdt],
@@ -269,6 +287,9 @@ if test "x$enable_tracing_instrumentation_usdt" = "xyes"; then
   AC_CHECK_HEADERS([sys/sdt.h], [],
                    [AC_MSG_ERROR([USDT instrumentation requires sys/sdt.h header.
                                   On Debian, apt install systemtap-sdt-dev])], [])
+  dnl LTTng generates USDT probes if the UST library was built with
+  dnl --with-sdt. There is unfortunately no way to check that so we always
+  dnl build the USDT probes even though LTTng instrumentation was requested.
   AC_DEFINE([USE_TRACING_INSTRUMENTATION_USDT], [1], [Using USDT instrumentation])
 fi
 
@@ -286,6 +307,11 @@ AM_COND_IF([USE_TRACING_INSTRUMENTATION_LOG_DEBUG],
            AC_DEFINE([HAVE_TRACING], [1], [Compiled with tracing support]))
 AM_COND_IF([USE_TRACING_INSTRUMENTATION_USDT],
            AC_DEFINE([HAVE_TRACING], [1], [Compiled with tracing support]))
+AM_COND_IF([USE_TRACING_INSTRUMENTATION_LTTNG],
+           AC_DEFINE([HAVE_TRACING], [1], [Compiled with tracing support]))
+
+dnl Finally, define the trace libs.
+AC_SUBST([TOR_TRACE_LIBS])
 
 dnl -- End Tracing Options. --
 
@@ -2750,6 +2776,9 @@ PPRINT_PROP_BOOL([Tracepoints to log_debug() (--enable-tracing-instrumentation-l
 test "x$enable_tracing_instrumentation_usdt" = "xyes" && value=1 || value=0
 PPRINT_PROP_BOOL([USDT Instrumentation (--enable-tracing-instrumentation-usdt)], $value)
 
+test "x$enable_tracing_instrumentation_lttng" = "xyes" && value=1 || value=0
+PPRINT_PROP_BOOL([LTTng Instrumentation (--enable-tracing-instrumentation-lttng)], $value)
+
 AS_ECHO
 PPRINT_SUBTITLE([Install Directories])
 

src/app/include.am

@@ -20,7 +20,7 @@ src_app_tor_LDADD = $(TOR_INTERNAL_LIBS) \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ $(TOR_LIBS_CRYPTLIB) \
 	@TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @TOR_LIB_USERENV@ \
 	@CURVE25519_LIBS@ @TOR_SYSTEMD_LIBS@ \
-	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ @TOR_TRACE_LIBS@
 
 if COVERAGE_ENABLED
 src_app_tor_cov_SOURCES = $(src_app_tor_SOURCES)
@@ -31,5 +31,5 @@ src_app_tor_cov_LDADD = $(TOR_INTERNAL_TESTING_LIBS) \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ $(TOR_LIBS_CRYPTLIB) \
 	@TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ \
 	@CURVE25519_LIBS@ @TOR_SYSTEMD_LIBS@ \
-	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ @TOR_TRACE_LIBS@
 endif

src/lib/trace/events.h

@@ -17,6 +17,7 @@
   do {                                                              \
     TOR_TRACE_LOG_DEBUG(tor_ ## subsystem, event_name);             \
     TOR_TRACE_USDT(tor_ ## subsystem, event_name, ## __VA_ARGS__);  \
+    TOR_TRACE_LTTNG(tor_ ## subsystem, event_name, ## __VA_ARGS__); \
   } while (0)
 
 /* This corresponds to the --enable-tracing-instrumentation-log-debug
@@ -27,6 +28,10 @@
  * option which will generate USDT probes for each tracepoints. */
 #include "lib/trace/usdt/usdt.h"
 
+/* This corresponds to the --enable-tracing-instrumentation-lttng configure
+ * option which will generate LTTng probes for each tracepoints. */
+#include "lib/trace/lttng/lttng.h"
+
 #else /* !defined(HAVE_TRACING) */
 
 /* Reaching this point, tracing is disabled thus we NOP every tracepoints

src/lib/trace/include.am

@@ -22,6 +22,10 @@ if USE_TRACING_INSTRUMENTATION_USDT
 include src/lib/trace/usdt/include.am
 endif
 
+if USE_TRACING_INSTRUMENTATION_LTTNG
+include src/lib/trace/lttng/include.am
+endif
+
 src_lib_libtor_trace_a_SOURCES = $(LIBTOR_TRACE_A_SOURCES)
 
 noinst_HEADERS+= $(TRACEHEADERS)

src/lib/trace/lttng/include.am

+# ADD_C_FILE: INSERT HEADERS HERE.
+TRACEHEADERS += \
+	src/lib/trace/lttng/lttng.h

src/lib/trace/lttng/lttng.h

+/* Copyright (c) 2020, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file lttng.h
+ * \brief Header file for lttng.c.
+ **/
+
+#ifndef TOR_TRACE_LTTNG_LTTNG_H
+#define TOR_TRACE_LTTNG_LTTNG_H
+
+#ifdef USE_TRACING_INSTRUMENTATION_LTTNG
+
+#include <lttng/tracepoint.h>
+
+/* Map event to an LTTng tracepoint. */
+#define TOR_TRACE_LTTNG(subsystem, event_name, ...) \
+  tracepoint(subsystem, event_name, ## __VA_ARGS__)
+
+#else /* !defined(USE_TRACING_INSTRUMENTATION_LTTNG) */
+
+/* NOP event. */
+#define TOR_TRACE_LTTNG(subsystem, event_name, ...)
+
+#endif /* !defined(USE_TRACING_INSTRUMENTATION_LTTNG) */
+
+#endif /* TOR_TRACE_LTTNG_LTTNG_H */
+

src/test/fuzz/include.am

@@ -14,7 +14,7 @@ FUZZING_LIBS = \
 	@TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @TOR_LIB_USERENV@ @CURVE25519_LIBS@ \
 	@TOR_SYSTEMD_LIBS@ \
 	@TOR_LZMA_LIBS@ \
-	@TOR_ZSTD_LIBS@
+	@TOR_ZSTD_LIBS@ @TOR_TRACE_LIBS@
 
 oss-fuzz-prereqs: \
     $(TOR_INTERNAL_TESTING_LIBS)

src/test/include.am

@@ -297,7 +297,7 @@ src_test_test_switch_id_LDADD = \
 	$(rust_ldadd) \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ \
 	@TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_USERENV@ \
-	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ @TOR_TRACE_LIBS@
 
 src_test_test_LDFLAGS = @TOR_LDFLAGS_zlib@ $(TOR_LDFLAGS_CRYPTLIB) \
 	@TOR_LDFLAGS_libevent@
@@ -307,7 +307,7 @@ src_test_test_LDADD = \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \
 	$(TOR_LIBS_CRYPTLIB) @TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @TOR_LIB_USERENV@ \
 	@CURVE25519_LIBS@ \
-	@TOR_SYSTEMD_LIBS@ @TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_SYSTEMD_LIBS@ @TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ @TOR_TRACE_LIBS@
 
 src_test_test_slow_CPPFLAGS = $(src_test_test_CPPFLAGS)
 src_test_test_slow_CFLAGS = $(src_test_test_CFLAGS)
@@ -336,7 +336,7 @@ src_test_bench_LDADD = \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \
 	$(TOR_LIBS_CRYPTLIB) @TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @TOR_LIB_USERENV@ \
 	@CURVE25519_LIBS@ \
-	@TOR_SYSTEMD_LIBS@ @TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_SYSTEMD_LIBS@ @TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ @TOR_TRACE_LIBS@
 
 src_test_test_workqueue_LDFLAGS = @TOR_LDFLAGS_zlib@ $(TOR_LDFLAGS_CRYPTLIB) \
 	@TOR_LDFLAGS_libevent@
@@ -346,7 +346,7 @@ src_test_test_workqueue_LDADD = \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \
 	$(TOR_LIBS_CRYPTLIB) @TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @TOR_LIB_USERENV@ \
 	@CURVE25519_LIBS@ \
-	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ @TOR_TRACE_LIBS@
 
 src_test_test_timers_CPPFLAGS = $(src_test_test_CPPFLAGS)
 src_test_test_timers_CFLAGS = $(src_test_test_CFLAGS)
@@ -358,7 +358,7 @@ src_test_test_timers_LDADD = \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \
 	$(TOR_LIBS_CRYPTLIB) @TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @TOR_LIB_USERENV@ \
 	@CURVE25519_LIBS@ \
-	@TOR_LZMA_LIBS@
+	@TOR_LZMA_LIBS@ @TOR_TRACE_LIBS@
 src_test_test_timers_LDFLAGS = $(src_test_test_LDFLAGS)
 
 # ADD_C_FILE: INSERT HEADERS HERE.
@@ -394,7 +394,7 @@ src_test_test_ntor_cl_LDADD = \
 	$(rust_ldadd) \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ \
 	$(TOR_LIBS_CRYPTLIB) @TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @TOR_LIB_USERENV@ \
-	@CURVE25519_LIBS@ @TOR_LZMA_LIBS@
+	@CURVE25519_LIBS@ @TOR_LZMA_LIBS@ @TOR_TRACE_LIBS@
 src_test_test_ntor_cl_AM_CPPFLAGS =	       \
 	$(AM_CPPFLAGS)
 
@@ -403,7 +403,8 @@ src_test_test_hs_ntor_cl_LDFLAGS = @TOR_LDFLAGS_zlib@ $(TOR_LDFLAGS_CRYPTLIB)
 src_test_test_hs_ntor_cl_LDADD = \
 	$(TOR_INTERNAL_LIBS) \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ \
-	$(TOR_LIBS_CRYPTLIB) @TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @CURVE25519_LIBS@
+	$(TOR_LIBS_CRYPTLIB) @TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ \
+	@CURVE25519_LIBS@ @TOR_TRACE_LIBS@
 src_test_test_hs_ntor_cl_AM_CPPFLAGS =	       \
 	$(AM_CPPFLAGS)
 
@@ -415,7 +416,8 @@ src_test_test_bt_cl_LDADD = \
 	$(TOR_UTIL_TESTING_LIBS) \
 	$(rust_ldadd) \
 	@TOR_LIB_MATH@ \
-	@TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @TOR_LIB_USERENV@
+	@TOR_LIB_WS32@ @TOR_LIB_IPHLPAPI@ @TOR_LIB_GDI@ @TOR_LIB_USERENV@ \
+	@TOR_TRACE_LIBS@
 src_test_test_bt_cl_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
 src_test_test_bt_cl_CPPFLAGS= $(src_test_AM_CPPFLAGS) $(TEST_CPPFLAGS)
 endif