linux-kernel - Re: [PATCH v2 0/3] Use BPF filters for a "perf top -u" workaround

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Message-ID: <ZlDVLBQ84O7fN9K4@google.com>
Date: Fri, 24 May 2024 10:58:04 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Changbin Du <changbin.du@...wei.com>,
	John Fastabend <john.fastabend@...il.com>,
	Andrii Nakryiko <andrii@...nel.org>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org
Subject: Re: [PATCH v2 0/3] Use BPF filters for a "perf top -u" workaround

On Wed, May 22, 2024 at 09:38:57PM -0700, Namhyung Kim wrote:
> On Mon, May 20, 2024 at 6:04 PM Ian Rogers <irogers@...gle.com> wrote:
> >
> > Allow uid and gid to be terms in BPF filters by first breaking the
> > connection between filter terms and PERF_SAMPLE_xx values. Calculate
> > the uid and gid using the bpf_get_current_uid_gid helper, rather than
> > from a value in the sample. Allow filters to be passed to perf top, this allows:
> >
> > $ perf top -e cycles:P --filter "uid == $(id -u)"
> >
> > to work as a "perf top -u" workaround, as "perf top -u" usually fails
> > due to processes/threads terminating between the /proc scan and the
> > perf_event_open.
> >
> > v2. Allow PERF_SAMPLE_xx to be computed from the PBF_TERM_xx value
> >     using a shift as requested by Namhyung.
> >
> > Ian Rogers (3):
> >   perf bpf filter: Give terms their own enum
> >   perf bpf filter: Add uid and gid terms
> >   perf top: Allow filters on events

Hmm.. I'm seeing this.

  $ make build-test
  ...
  cd . && make GEN_VMLINUX_H=1 FEATURES_DUMP=/home/namhyung/project/linux/tools/perf/BUILD_TEST_FEATURE_DUMP -j64 O=/tmp/tmp.EeXFOfLPt5 DESTDIR=/tmp/tmp.Y0eiZKvc9D
  ...
    CLANG   /tmp/tmp.EeXFOfLPt5/util/bpf_skel/.tmp/sample_filter.bpf.o            
  In file included from util/bpf_skel/sample_filter.bpf.c:8:                      
  In file included from util/bpf_skel/sample-filter.h:4:                          
  /home/namhyung/project/linux/tools/include/uapi/linux/perf_event.h:29:6: error: redefinition of 'perf_type_id'
  enum perf_type_id {                                                             
       ^                                                                          
  /tmp/tmp.EeXFOfLPt5/util/bpf_skel/.tmp/../vmlinux.h:54086:6: note: previous definition is here
  enum perf_type_id {                                                             
       ^                                                                          
  In file included from util/bpf_skel/sample_filter.bpf.c:8:                      
  In file included from util/bpf_skel/sample-filter.h:4:                          
  /home/namhyung/project/linux/tools/include/uapi/linux/perf_event.h:30:2: error: redefinition of enumerator 'PERF_TYPE_HARDWARE'
          PERF_TYPE_HARDWARE                      = 0,                            
          ^                                                                       
  /tmp/tmp.EeXFOfLPt5/util/bpf_skel/.tmp/../vmlinux.h:54087:2: note: previous definition is here
          PERF_TYPE_HARDWARE = 0,                                                 
          ^
  ...
  make[3]: *** [Makefile.perf:264: sub-make] Error 2                              
  make[2]: *** [Makefile:70: all] Error 2                                         
  make[1]: *** [tests/make:340: make_gen_vmlinux_h_O] Error 1                     
  make: *** [Makefile:103: build-test] Error 2

Thanks,
Namhyung