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

[Yang Jihong]

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