perf tools: Enable libtraceevent dynamic linking

Currently we support only static linking with kernel's libtraceevent
(tools/lib/traceevent). This patch adds libtraceevent package detection
and support to link perf with it dynamically.

  The libtraceevent package status is displayed with:
  $ make VF=1 LIBTRACEEVENT_DYNAMIC=1
  ...
  ...                 libtraceevent: [ on  ]

Default behavior remains the same (static linking).

Committer testing:

  $ make LIBTRACEEVENT_DYNAMIC=1 VF=1 O=/tmp/build/perf -C tools/perf install-bin |& grep traceevent
  Makefile.config:1090: *** Error: No libtraceevent devel library found, please install libtraceevent-devel.  Stop.
  $
Signed-off-by: NMichael Petlan <mpetlan@redhat.com>
Tested-by: NArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
LPU-Reference: 20210428092023.4009-1-mpetlan@redhat.com
Signed-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/build/Makefile.feature

@@ -52,6 +52,7 @@ FEATURE_TESTS_BASIC :=                  \
         libpython-version               \
         libslang                        \
         libslang-include-subdir         \
+        libtraceevent                   \
         libcrypto                       \
         libunwind                       \
         pthread-attr-setaffinity-np     \

tools/build/feature/Makefile

@@ -36,6 +36,7 @@ FILES=                                          \
          test-libpython-version.bin             \
          test-libslang.bin                      \
          test-libslang-include-subdir.bin       \
+         test-libtraceevent.bin                 \
          test-libcrypto.bin                     \
          test-libunwind.bin                     \
          test-libunwind-debug-frame.bin         \
@@ -196,6 +197,9 @@ $(OUTPUT)test-libslang.bin:
 $(OUTPUT)test-libslang-include-subdir.bin:
 	$(BUILD) -lslang
 
+$(OUTPUT)test-libtraceevent.bin:
+	$(BUILD) -ltraceevent
+
 $(OUTPUT)test-libcrypto.bin:
 	$(BUILD) -lcrypto
 

tools/build/feature/test-libtraceevent.c

+// SPDX-License-Identifier: GPL-2.0
+#include <traceevent/trace-seq.h>
+
+int main(void)
+{
+	int rv = 0;
+	struct trace_seq s;
+	trace_seq_init(&s);
+	rv += !(s.state == TRACE_SEQ__GOOD);
+	trace_seq_destroy(&s);
+	return rv;
+}

tools/perf/Makefile.config

@@ -1079,6 +1079,15 @@ ifdef LIBPFM4
   endif
 endif
 
+ifdef LIBTRACEEVENT_DYNAMIC
+  $(call feature_check,libtraceevent)
+  ifeq ($(feature-libtraceevent), 1)
+    EXTLIBS += -ltraceevent
+  else
+    dummy := $(error Error: No libtraceevent devel library found, please install libtraceevent-devel);
+  endif
+endif
+
 # Among the variables below, these:
 #   perfexecdir
 #   perf_include_dir

tools/perf/Makefile.perf

@@ -128,6 +128,8 @@ include ../scripts/utilities.mak
 #
 # Define BUILD_BPF_SKEL to enable BPF skeletons
 #
+# Define LIBTRACEEVENT_DYNAMIC to enable libtraceevent dynamic linking
+#
 
 # As per kernel Makefile, avoid funny character set dependencies
 unexport LC_ALL
@@ -310,7 +312,6 @@ endif
 
 LIBTRACEEVENT = $(TE_PATH)libtraceevent.a
 export LIBTRACEEVENT
-
 LIBTRACEEVENT_DYNAMIC_LIST = $(PLUGINS_PATH)libtraceevent-dynamic-list
 
 #
@@ -375,12 +376,15 @@ endif
 
 export PERL_PATH
 
-PERFLIBS = $(LIBAPI) $(LIBTRACEEVENT) $(LIBSUBCMD) $(LIBPERF)
+PERFLIBS = $(LIBAPI) $(LIBSUBCMD) $(LIBPERF)
 ifndef NO_LIBBPF
   ifndef LIBBPF_DYNAMIC
     PERFLIBS += $(LIBBPF)
   endif
 endif
+ifndef LIBTRACEEVENT_DYNAMIC
+  PERFLIBS += $(LIBTRACEEVENT)
+endif
 
 # We choose to avoid "if .. else if .. else .. endif endif"
 # because maintaining the nesting to match is a pain.  If