Re: [External] Re: [PATCH] perf build: Add LIBTRACEEVENT_DIR build option

From: Yang Jihong
Date: Mon May 06 2024 - 04:30:41 EST


Hello,

On 5/1/24 01:46, Ian Rogers wrote:
On Sat, Mar 23, 2024 at 12:07 PM Ian Rogers <irogers@xxxxxxxxxx> wrote:

On Wed, Mar 13, 2024 at 11:30 PM Yang Jihong <yangjihong@xxxxxxxxxxxxx> wrote:

Currently, when libtraceevent is not linked,
perf does not support tracepoint:

# ./perf record -e sched:sched_switch -a sleep 10
event syntax error: 'sched:sched_switch'
\___ unsupported tracepoint

libtraceevent is necessary for tracepoint support
Run 'perf list' for a list of valid events

Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]

-e, --event <event> event selector. use 'perf list' to list available events

For cross-compilation scenario, library may not be installed in the default
system path. Based on the above requirements, add LIBTRACEEVENT_DIR build
option to support specifying path of libtraceevent.

Example:

1. Cross compile libtraceevent
# cd /opt/libtraceevent
# CROSS_COMPILE=aarch64-linux-gnu- make

2. Cross compile perf
# cd tool/perf
# make VF=1 ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- NO_LIBELF=1 LDFLAGS=--static LIBTRACEEVENT_DIR=/opt/libtraceevent
<SNIP>
Auto-detecting system features:
<SNIP>
... LIBTRACEEVENT_DIR: /opt/libtraceevent

Signed-off-by: Yang Jihong <yangjihong@xxxxxxxxxxxxx>

This all looks good to me, thanks!

Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>

---
tools/perf/Makefile.config | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 1fe8df97fe88..7783479de691 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -182,6 +182,16 @@ endif
FEATURE_CHECK_CFLAGS-libzstd := $(LIBZSTD_CFLAGS)
FEATURE_CHECK_LDFLAGS-libzstd := $(LIBZSTD_LDFLAGS)

+# for linking with debug library, run like:
+# make DEBUG=1 LIBTRACEEVENT_DIR=/opt/libtraceevent/
+TRACEEVENTLIBS := -ltraceevent
+ifdef LIBTRACEEVENT_DIR
+ LIBTRACEEVENT_CFLAGS := -I$(LIBTRACEEVENT_DIR)/include
+ LIBTRACEEVENT_LDFLAGS := -L$(LIBTRACEEVENT_DIR)/lib
+endif

I'm finding to test a libtraceevent asan build on a system that has
libtraceevent installed, I need to carry this change:
```
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 7f1e016a9253..b356520d8291 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -187,7 +187,7 @@ FEATURE_CHECK_LDFLAGS-libzstd := $(LIBZSTD_LDFLAGS)
TRACEEVENTLIBS := -ltraceevent
ifdef LIBTRACEEVENT_DIR
LIBTRACEEVENT_CFLAGS := -I$(LIBTRACEEVENT_DIR)/include
- LIBTRACEEVENT_LDFLAGS := -L$(LIBTRACEEVENT_DIR)/lib
+ LIBTRACEEVENT_LDFLAGS := -Wl,-rpath,$(LIBTRACEEVENT_DIR)/lib64
endif
FEATURE_CHECK_CFLAGS-libtraceevent := $(LIBTRACEEVENT_CFLAGS)
FEATURE_CHECK_LDFLAGS-libtraceevent := $(LIBTRACEEVENT_LDFLAGS)
$(TRACEEVENTLIBS)
```

I'm not sure how to make this something that'll work well with cross
compilation, etc.

Because of the holiday, the reply is a bit late.

It seems that perf built by asan/msan will not search for shared libraries in the -L directory.
We generally use cross-compile perf to analyze performance problems. In most cases, it is static compilation (rpath does not work), and it will not enable sanitizers.
so can we simply check if EXTRA_CFLAGS contains -fsanitize=address/memory, and add libtraceevent dir to rpath?

I submitted a patch, please see if the solution is feasible:
https://lore.kernel.org/all/20240506081648.3890067-1-yangjihong@xxxxxxxxxxxxx/


Or we can add libtraceevent's ld.so.conf to the environment. This requires manual configuration of the build environment, which is inconvenient.

# echo "/opt/libtraceevent/lib" > /etc/ld.so.conf.d/libtracevent.conf
# ldconfig

Thanks,
Yang