commit 668fc70a20c602bb0e74bf0e19589a17bb45b7ae Author: David Goulet dgoulet@torproject.org Date: Tue Jan 14 14:58:09 2020 -0500

trace: Add USDT probes generation support

This commit adds both configure options and probe generation for tracepoints.

Part of #32910

Signed-off-by: David Goulet dgoulet@torproject.org --- configure.ac | 21 ++++++++++++++++++++- src/lib/trace/events.h | 13 +++++++++---- src/lib/trace/include.am | 4 ++++ src/lib/trace/usdt/include.am | 3 +++ src/lib/trace/usdt/usdt.h | 33 +++++++++++++++++++++++++++++++++ 5 files changed, 69 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac index 680111b10..170d8dc20 100644 --- a/configure.ac +++ b/configure.ac @@ -258,6 +258,20 @@ AC_ARG_ENABLE(libscrypt,

dnl --- Tracing Options. ---

+dnl USDT instrumentation option. +AC_ARG_ENABLE(tracing-instrumentation-usdt, + AS_HELP_STRING([--enable-tracing-instrumentation-usdt], + [build with tracing USDT instrumentation])) +AM_CONDITIONAL([USE_TRACING_INSTRUMENTATION_USDT], + [test "x$enable_tracing_instrumentation_usdt" = "xyes"]) + +if test "x$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])], []) + AC_DEFINE([USE_TRACING_INSTRUMENTATION_USDT], [1], [Using USDT instrumentation]) +fi + dnl Tracepoints event to debug logs. AC_ARG_ENABLE(tracing-instrumentation-log-debug, AS_HELP_STRING([--enable-tracing-instrumentation-log-debug], @@ -267,9 +281,11 @@ AC_ARG_ENABLE(tracing-instrumentation-log-debug, AM_CONDITIONAL([USE_TRACING_INSTRUMENTATION_LOG_DEBUG], [test "x$enable_tracing_instrumentation_log_debug" = "xyes"])

-dnl Define that tracing is supported. +dnl Define that tracing is supported if any instrumentation is used. 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]))

dnl -- End Tracing Options. --

@@ -2731,6 +2747,9 @@ PPRINT_SUBTITLE([Tracing]) test "x$enable_tracing_instrumentation_log_debug" = "xyes" && value=1 || value=0 PPRINT_PROP_BOOL([Tracepoints to log_debug() (--enable-tracing-instrumentation-log-debug)], $value)

+test "x$enable_tracing_instrumentation_usdt" = "xyes" && value=1 || value=0 +PPRINT_PROP_BOOL([USDT Instrumentation (--enable-tracing-instrumentation-usdt)], $value) + AS_ECHO PPRINT_SUBTITLE([Install Directories])

diff --git a/src/lib/trace/events.h b/src/lib/trace/events.h index b1b31fdc9..fcd31e24e 100644 --- a/src/lib/trace/events.h +++ b/src/lib/trace/events.h @@ -3,7 +3,7 @@

/** * \file events.h - * \brief Header file for Tor event tracing. + * \brief Header file for Tor tracing instrumentation definition. **/

#ifndef TOR_LIB_TRACE_EVENTS_H @@ -13,15 +13,20 @@

#ifdef HAVE_TRACING

-#define tor_trace(subsystem, event_name, ...) \ - do { \ - TOR_TRACE_LOG_DEBUG(tor_ ## subsystem, event_name); \ +#define tor_trace(subsystem, event_name, ...) \ + do { \ + TOR_TRACE_LOG_DEBUG(tor_ ## subsystem, event_name); \ + TOR_TRACE_USDT(tor_ ## subsystem, event_name, ## __VA_ARGS__); \ } while (0)

/* This corresponds to the --enable-tracing-instrumentation-log-debug * configure option which maps all tracepoints to a log_debug() statement. */ #include "lib/trace/debug.h"

+/* This corresponds to the --enable-tracing-instrumentation-usdt configure + * option which will generate USDT probes for each tracepoints. */ +#include "lib/trace/usdt/usdt.h" + #else /* !defined(HAVE_TRACING) */

/* Reaching this point, tracing is disabled thus we NOP every tracepoints diff --git a/src/lib/trace/include.am b/src/lib/trace/include.am index 312fd4e87..01ea0c8a1 100644 --- a/src/lib/trace/include.am +++ b/src/lib/trace/include.am @@ -18,6 +18,10 @@ TRACEHEADERS += \ src/lib/trace/debug.h endif

+if USE_TRACING_INSTRUMENTATION_USDT +include src/lib/trace/usdt/include.am +endif + src_lib_libtor_trace_a_SOURCES = $(LIBTOR_TRACE_A_SOURCES)

noinst_HEADERS+= $(TRACEHEADERS) diff --git a/src/lib/trace/usdt/include.am b/src/lib/trace/usdt/include.am new file mode 100644 index 000000000..4e7e04c32 --- /dev/null +++ b/src/lib/trace/usdt/include.am @@ -0,0 +1,3 @@ +# ADD_C_FILE: INSERT HEADERS HERE. +TRACEHEADERS += \ + src/lib/trace/usdt/usdt.h diff --git a/src/lib/trace/usdt/usdt.h b/src/lib/trace/usdt/usdt.h new file mode 100644 index 000000000..0b5fd6c44 --- /dev/null +++ b/src/lib/trace/usdt/usdt.h @@ -0,0 +1,33 @@ +/* Copyright (c) 2020, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +/** + * \file trace.h + * \brief Header for usdt.h + **/ + +#ifndef TOR_TRACE_USDT_USDT_H +#define TOR_TRACE_USDT_USDT_H + +#ifdef USE_TRACING_INSTRUMENTATION_USDT + +#ifdef HAVE_SYS_SDT_H +#define SDT_USE_VARIADIC +#include <sys/sdt.h> +#define TOR_STAP_PROBEV STAP_PROBEV +#else /* defined(HAVE_SYS_SDT_H) */ +#define TOR_STAP_PROBEV(...) +#endif + +/* Map events to an USDT probe. */ +#define TOR_TRACE_USDT(subsystem, event_name, ...) \ + TOR_STAP_PROBEV(subsystem, event_name, ## __VA_ARGS__); + +#else /* !defined(USE_TRACING_INSTRUMENTATION_USDT) */ + +/* NOP event. */ +#define TOR_TRACE_USDT(subsystem, event_name, ...) + +#endif /* !defined(USE_TRACING_INSTRUMENTATION_USDT) */ + +#endif /* !defined(TOR_TRACE_USDT_USDT_H) */