tools lib traceevent: Export dynamic symbols used by traceevent plugins

Traceevent plugins need dynamic symbols exported from libtraceevent.a,
otherwise a dlopen error will occur during plugins loading.

This patch uses dynamic-list-file to export dynamic symbols which will
be used in plugins to perf executable.

The problem is covered up if feature-libpython is enabled, because
PYTHON_EMBED_LDOPTS contains '-Xlinker --export-dynamic' which adds all
symbols to the dynamic symbol table. So we should reproduce the problem
by setting NO_LIBPYTHON=1.

Before this patch:

(Prepare plugins)
$ ls /root/.traceevent/plugins/
plugin_sched_switch.so
plugin_function.so
...

$ perf record -e 'ftrace:function' ls

$ perf script
Warning: could not load plugin '/mnt/data/root/.traceevent/plugins/plugin_sched_switch.so'
/root/.traceevent/plugins/plugin_sched_switch.so: undefined symbol: pevent_unregister_event_handler

Warning: could not load plugin '/root/.traceevent/plugins/plugin_function.so'
/root/.traceevent/plugins/plugin_function.so: undefined symbol: warning
...
:1049 1049 [000] 9666.754487: ftrace:function: ffffffff8118bc50 <-- ffffffff8118c5b3
:1049 1049 [000] 9666.754487: ftrace:function: ffffffff818e2440 <-- ffffffff8118bc75
:1049 1049 [000] 9666.754487: ftrace:function: ffffffff8106eee0 <-- ffffffff811212e2

After this patch:

$ perf record -e 'ftrace:function' ls
$ perf script
:1049 1049 [000] 9666.754487: ftrace:function: __set_task_comm
:1049 1049 [000] 9666.754487: ftrace:function: _raw_spin_lock
:1049 1049 [000] 9666.754487: ftrace:function: task_tgid_nr_ns
...

Signed-off-by: He Kuang <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/traceevent/Makefile

···
 # Allow setting CC and AR, or setting CROSS_COMPILE as a prefix.
 $(call allow-override,CC,$(CROSS_COMPILE)gcc)
 $(call allow-override,AR,$(CROSS_COMPILE)ar)
+$(call allow-override,NM,$(CROSS_COMPILE)nm)
 
 EXT = -std=gnu99
 INSTALL = install
···
 
 TE_IN    := $(OUTPUT)libtraceevent-in.o
 LIB_FILE := $(addprefix $(OUTPUT),$(LIB_FILE))
+DYNAMIC_LIST_FILE := $(OUTPUT)libtraceevent-dynamic-list
 
-CMD_TARGETS = $(LIB_FILE) $(PLUGINS)
+CMD_TARGETS = $(LIB_FILE) $(PLUGINS) $(DYNAMIC_LIST_FILE)
 
 TARGETS = $(CMD_TARGETS)
 
···
 
 $(OUTPUT)libtraceevent.a: $(TE_IN)
 	$(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^
+
+$(OUTPUT)libtraceevent-dynamic-list: $(PLUGINS)
+	$(QUIET_GEN)$(call do_generate_dynamic_list_file, $(PLUGINS), $@)
 
 plugins: $(PLUGINS)
 
···
 	for plugin in $1; do				\
 	  $(call do_install,$$plugin,$(plugin_dir_SQ));	\
 	done
+endef
+
+define do_generate_dynamic_list_file
+	(echo '{';							\
+	$(NM) -u -D $1 | awk 'NF>1 {print "\t"$$2";"}' | sort -u;	\
+	echo '};';							\
+	) > $2
 endef
 
 install_lib: all_cmd install_plugins

tools/perf/Makefile.perf

···
 LIBTRACEEVENT = $(TE_PATH)libtraceevent.a
 export LIBTRACEEVENT
 
+LIBTRACEEVENT_DYNAMIC_LIST = $(TE_PATH)libtraceevent-dynamic-list
+LDFLAGS += -Xlinker --dynamic-list=$(LIBTRACEEVENT_DYNAMIC_LIST)
+
 LIBAPI = $(LIB_PATH)libapi.a
 export LIBAPI
 
···
 $(PERF_IN): $(OUTPUT)PERF-VERSION-FILE $(OUTPUT)common-cmds.h FORCE
 	$(Q)$(MAKE) $(build)=perf
 
-$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN)
+$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN) $(LIBTRACEEVENT_DYNAMIC_LIST)
 	$(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(PERF_IN) $(LIBS) -o $@
 
 $(GTK_IN): FORCE
···
 LIBTRACEEVENT_FLAGS += plugin_dir=$(plugindir_SQ)
 
 $(LIBTRACEEVENT): FORCE
-	$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) $(OUTPUT)libtraceevent.a plugins
+	$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) $(OUTPUT)libtraceevent.a
+
+libtraceevent_plugins: FORCE
+	$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) plugins
+
+$(LIBTRACEEVENT_DYNAMIC_LIST): libtraceevent_plugins
+	$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) $(OUTPUT)libtraceevent-dynamic-list
 
 $(LIBTRACEEVENT)-clean:
 	$(call QUIET_CLEAN, libtraceevent)
···
 .PHONY: all install clean config-clean strip install-gtk
 .PHONY: shell_compatibility_test please_set_SHELL_PATH_to_a_more_modern_shell
 .PHONY: $(GIT-HEAD-PHONY) TAGS tags cscope FORCE single_dep
+.PHONY: libtraceevent_plugins