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Subject[PATCH 1/2] tools lib traceevent: Export dynamic symbols used by traceevent plugins
Date
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 <hekuang@huawei.com>
---
tools/lib/traceevent/Makefile | 14 +++++++++++++-
tools/perf/Makefile.perf | 9 +++++++--
2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/tools/lib/traceevent/Makefile b/tools/lib/traceevent/Makefile
index d410da3..2cbac13 100644
--- a/tools/lib/traceevent/Makefile
+++ b/tools/lib/traceevent/Makefile
@@ -23,6 +23,7 @@ endef
# 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
@@ -151,8 +152,9 @@ PLUGINS_IN := $(PLUGINS:.so=-in.o)

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)

@@ -169,6 +171,9 @@ $(OUTPUT)libtraceevent.so: $(TE_IN)
$(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)

__plugin_obj = $(notdir $@)
@@ -238,6 +243,13 @@ define do_install_plugins
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
$(call QUIET_INSTALL, $(LIB_FILE)) \
$(call do_install,$(LIB_FILE),$(bindir_SQ))
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 03409cc..19c61e0 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -172,6 +172,7 @@ endif

LIBTRACEEVENT = $(TE_PATH)libtraceevent.a
export LIBTRACEEVENT
+LIBTRACEEVENT_DYNAMIC_LIST = $(TE_PATH)libtraceevent-dynamic-list

LIBAPI = $(LIB_PATH)libapi.a
export LIBAPI
@@ -278,8 +279,9 @@ build := -f $(srctree)/tools/build/Makefile.build dir=. obj
$(PERF_IN): $(OUTPUT)PERF-VERSION-FILE $(OUTPUT)common-cmds.h FORCE
$(Q)$(MAKE) $(build)=perf

-$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN)
- $(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(PERF_IN) $(LIBS) -o $@
+LD_LIBTRACEEVENT_FLAGS += -Xlinker --dynamic-list=$(LIBTRACEEVENT_DYNAMIC_LIST)
+$(OUTPUT)perf: $(PERFLIBS) $(PERF_IN) $(LIBTRACEEVENT_DYNAMIC_LIST)
+ $(QUIET_LINK)$(CC) $(CFLAGS) $(LDFLAGS) $(LD_LIBTRACEEVENT_FLAGS) $(PERF_IN) $(LIBS) -o $@

$(GTK_IN): FORCE
$(Q)$(MAKE) $(build)=gtk
@@ -375,6 +377,9 @@ LIBTRACEEVENT_FLAGS += plugin_dir=$(plugindir_SQ)
$(LIBTRACEEVENT): FORCE
$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) $(OUTPUT)libtraceevent.a plugins

+$(LIBTRACEEVENT_DYNAMIC_LIST): $(LIBTRACEEVENT)
+ $(Q)$(MAKE) -C $(TRACE_EVENT_DIR) $(LIBTRACEEVENT_FLAGS) O=$(OUTPUT) $(OUTPUT)libtraceevent-dynamic-list
+
$(LIBTRACEEVENT)-clean:
$(call QUIET_CLEAN, libtraceevent)
$(Q)$(MAKE) -C $(TRACE_EVENT_DIR) O=$(OUTPUT) clean >/dev/null
--
1.8.5.2


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