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From:   Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Date:   Mon, 18 May 2020 12:20:28 -0300
To:     Jiri Olsa <jolsa@redhat.com>
Cc:     Jiri Olsa <jolsa@kernel.org>, lkml <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Michael Petlan <mpetlan@redhat.com>
Subject: Re: [RFC] perf trace: Fix compilation error for make NO_LIBBPF=1
 DEBUG=1
Message-ID: <20200518152028.GC24211@kernel.org>
References: <20200518141027.3765877-1-jolsa@kernel.org>
 <20200518141915.GA24211@kernel.org>
 <20200518143528.GA2809@krava>
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Em Mon, May 18, 2020 at 04:35:28PM +0200, Jiri Olsa escreveu:
> On Mon, May 18, 2020 at 11:19:15AM -0300, Arnaldo Carvalho de Melo wrote:
> > Em Mon, May 18, 2020 at 04:10:27PM +0200, Jiri Olsa escreveu:
> > > I haven't tested if this breaks some perf trace functionality,
> > > hence RFC ;-)
> > 
> > Thanks for the patch, looks ok, applying, please let me know if you need
> > to do something else with it.
> 
> just wasn't sure the hook will work with NULL,
> so if you're ok with it, then it's ok ;-)

I looked at the places leading into that, should be ok :-)

- Arnaldo
 
> thanks,
> jirka
> 
> > 
> > - Arnaldo
> >  
> > > The perf compilation fails for NO_LIBBPF=1 DEBUG=1 with:
> > > 
> > >   $ make NO_LIBBPF=1 DEBUG=1
> > >     BUILD:   Doing 'make -j8' parallel build
> > >     CC       builtin-trace.o
> > >     LD       perf-in.o
> > >     LINK     perf
> > >   /usr/bin/ld: perf-in.o: in function `trace__find_bpf_map_by_name':
> > >   /home/jolsa/kernel/linux-perf/tools/perf/builtin-trace.c:4608: undefined reference to `bpf_object__find_map_by_name'
> > >   collect2: error: ld returned 1 exit status
> > >   make[2]: *** [Makefile.perf:631: perf] Error 1
> > >   make[1]: *** [Makefile.perf:225: sub-make] Error 2
> > >   make: *** [Makefile:70: all] Error 2
> > > 
> > > Moving trace__find_bpf_map_by_name calls under HAVE_LIBBPF_SUPPORT
> > > ifdef and add make test for this.
> > > 
> > > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > > ---
> > >  tools/perf/builtin-trace.c | 54 ++++++++++++++++++++++++--------------
> > >  tools/perf/tests/make      |  1 +
> > >  2 files changed, 35 insertions(+), 20 deletions(-)
> > > 
> > > diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
> > > index 56bcf1ab19f8..61bafca1018a 100644
> > > --- a/tools/perf/builtin-trace.c
> > > +++ b/tools/perf/builtin-trace.c
> > > @@ -3174,6 +3174,26 @@ static int trace__set_ev_qualifier_tp_filter(struct trace *trace)
> > >  }
> > >  
> > >  #ifdef HAVE_LIBBPF_SUPPORT
> > > +static struct bpf_map *trace__find_bpf_map_by_name(struct trace *trace, const char *name)
> > > +{
> > > +	if (trace->bpf_obj == NULL)
> > > +		return NULL;
> > > +
> > > +	return bpf_object__find_map_by_name(trace->bpf_obj, name);
> > > +}
> > > +
> > > +static void trace__set_bpf_map_filtered_pids(struct trace *trace)
> > > +{
> > > +	trace->filter_pids.map = trace__find_bpf_map_by_name(trace, "pids_filtered");
> > > +}
> > > +
> > > +static void trace__set_bpf_map_syscalls(struct trace *trace)
> > > +{
> > > +	trace->syscalls.map = trace__find_bpf_map_by_name(trace, "syscalls");
> > > +	trace->syscalls.prog_array.sys_enter = trace__find_bpf_map_by_name(trace, "syscalls_sys_enter");
> > > +	trace->syscalls.prog_array.sys_exit  = trace__find_bpf_map_by_name(trace, "syscalls_sys_exit");
> > > +}
> > > +
> > >  static struct bpf_program *trace__find_bpf_program_by_title(struct trace *trace, const char *name)
> > >  {
> > >  	if (trace->bpf_obj == NULL)
> > > @@ -3512,6 +3532,20 @@ static void trace__delete_augmented_syscalls(struct trace *trace)
> > >  	trace->bpf_obj = NULL;
> > >  }
> > >  #else // HAVE_LIBBPF_SUPPORT
> > > +static struct bpf_map *trace__find_bpf_map_by_name(struct trace *trace __maybe_unused,
> > > +						   const char *name __maybe_unused)
> > > +{
> > > +	return NULL;
> > > +}
> > > +
> > > +static void trace__set_bpf_map_filtered_pids(struct trace *trace __maybe_unused)
> > > +{
> > > +}
> > > +
> > > +static void trace__set_bpf_map_syscalls(struct trace *trace __maybe_unused)
> > > +{
> > > +}
> > > +
> > >  static int trace__set_ev_qualifier_bpf_filter(struct trace *trace __maybe_unused)
> > >  {
> > >  	return 0;
> > > @@ -4600,26 +4634,6 @@ static int trace__parse_cgroups(const struct option *opt, const char *str, int u
> > >  	return 0;
> > >  }
> > >  
> > > -static struct bpf_map *trace__find_bpf_map_by_name(struct trace *trace, const char *name)
> > > -{
> > > -	if (trace->bpf_obj == NULL)
> > > -		return NULL;
> > > -
> > > -	return bpf_object__find_map_by_name(trace->bpf_obj, name);
> > > -}
> > > -
> > > -static void trace__set_bpf_map_filtered_pids(struct trace *trace)
> > > -{
> > > -	trace->filter_pids.map = trace__find_bpf_map_by_name(trace, "pids_filtered");
> > > -}
> > > -
> > > -static void trace__set_bpf_map_syscalls(struct trace *trace)
> > > -{
> > > -	trace->syscalls.map = trace__find_bpf_map_by_name(trace, "syscalls");
> > > -	trace->syscalls.prog_array.sys_enter = trace__find_bpf_map_by_name(trace, "syscalls_sys_enter");
> > > -	trace->syscalls.prog_array.sys_exit  = trace__find_bpf_map_by_name(trace, "syscalls_sys_exit");
> > > -}
> > > -
> > >  static int trace__config(const char *var, const char *value, void *arg)
> > >  {
> > >  	struct trace *trace = arg;
> > > diff --git a/tools/perf/tests/make b/tools/perf/tests/make
> > > index 5d0c3a9c47a1..c3c59def9f87 100644
> > > --- a/tools/perf/tests/make
> > > +++ b/tools/perf/tests/make
> > > @@ -84,6 +84,7 @@ make_no_libaudit    := NO_LIBAUDIT=1
> > >  make_no_libbionic   := NO_LIBBIONIC=1
> > >  make_no_auxtrace    := NO_AUXTRACE=1
> > >  make_no_libbpf	    := NO_LIBBPF=1
> > > +make_no_libbpf_DEBUG := NO_LIBBPF=1 DEBUG=1
> > >  make_no_libcrypto   := NO_LIBCRYPTO=1
> > >  make_with_babeltrace:= LIBBABELTRACE=1
> > >  make_no_sdt	    := NO_SDT=1
> > > -- 
> > > 2.25.4
> > > 
> > 
> > -- 
> > 
> > - Arnaldo
> > 
> 

-- 

- Arnaldo