linux-kernel - Re: [PATCH v3 00/10] Move uid filtering to BPF filters

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Message-ID: <aD586_XkeOH2_Fes@google.com>
Date: Mon, 2 Jun 2025 21:41:15 -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>,
	James Clark <james.clark@...aro.org>,
	Dapeng Mi <dapeng1.mi@...ux.intel.com>,
	Thomas Richter <tmricht@...ux.ibm.com>,
	Veronika Molnarova <vmolnaro@...hat.com>, Hao Ge <gehao@...inos.cn>,
	Howard Chu <howardchu95@...il.com>,
	Weilin Wang <weilin.wang@...el.com>, Levi Yun <yeoreum.yun@....com>,
	"Dr. David Alan Gilbert" <linux@...blig.org>,
	Dominique Martinet <asmadeus@...ewreck.org>,
	Xu Yang <xu.yang_2@....com>, Tengda Wu <wutengda@...weicloud.com>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org
Subject: Re: [PATCH v3 00/10] Move uid filtering to BPF filters

Hi Ian,

On Tue, May 27, 2025 at 01:39:21PM -0700, Ian Rogers wrote:
> On Fri, Apr 25, 2025 at 2:40 PM Ian Rogers <irogers@...gle.com> wrote:
> >
> > Rather than scanning /proc and skipping PIDs based on their UIDs, use
> > BPF filters for uid filtering. The /proc scanning in thread_map is
> > racy as the PID may exit before the perf_event_open causing perf to
> > abort. BPF UID filters are more robust as they avoid the race. The
> > /proc scanning also misses processes starting after the perf
> > command. Add a helper for commands that support UID filtering and wire
> > up. Remove the non-BPF UID filtering support given it doesn't work.
> >
> > v3: Add lengthier commit messages as requested by Arnaldo. Rebase on
> >     tmp.perf-tools-next.
> >
> > v2: Add a perf record uid test (Namhyung) and force setting
> >     system-wide for perf trace and perf record (Namhyung). Ensure the
> >     uid filter isn't set on tracepoint evsels.
> >
> > v1: https://lore.kernel.org/lkml/20250111190143.1029906-1-irogers@google.com/
> 
> Ping. Thanks,

I'm ok with preferring BPF over /proc scanning, but still hesitate to
remove it since some people don't use BPF.  Can you please drop that
part and make parse_uid_filter() conditional on BPF?

Thanks,
Namhyung

 
> > Ian Rogers (10):
> >   perf parse-events filter: Use evsel__find_pmu
> >   perf target: Separate parse_uid into its own function
> >   perf parse-events: Add parse_uid_filter helper
> >   perf record: Switch user option to use BPF filter
> >   perf tests record: Add basic uid filtering test
> >   perf top: Switch user option to use BPF filter
> >   perf trace: Switch user option to use BPF filter
> >   perf bench evlist-open-close: Switch user option to use BPF filter
> >   perf target: Remove uid from target
> >   perf thread_map: Remove uid options
> >
> >  tools/perf/bench/evlist-open-close.c        | 36 ++++++++------
> >  tools/perf/builtin-ftrace.c                 |  1 -
> >  tools/perf/builtin-kvm.c                    |  2 -
> >  tools/perf/builtin-record.c                 | 27 ++++++-----
> >  tools/perf/builtin-stat.c                   |  4 +-
> >  tools/perf/builtin-top.c                    | 22 +++++----
> >  tools/perf/builtin-trace.c                  | 27 +++++++----
> >  tools/perf/tests/backward-ring-buffer.c     |  1 -
> >  tools/perf/tests/event-times.c              |  8 ++-
> >  tools/perf/tests/keep-tracking.c            |  2 +-
> >  tools/perf/tests/mmap-basic.c               |  2 +-
> >  tools/perf/tests/openat-syscall-all-cpus.c  |  2 +-
> >  tools/perf/tests/openat-syscall-tp-fields.c |  1 -
> >  tools/perf/tests/openat-syscall.c           |  2 +-
> >  tools/perf/tests/perf-record.c              |  1 -
> >  tools/perf/tests/perf-time-to-tsc.c         |  2 +-
> >  tools/perf/tests/shell/record.sh            | 26 ++++++++++
> >  tools/perf/tests/switch-tracking.c          |  2 +-
> >  tools/perf/tests/task-exit.c                |  1 -
> >  tools/perf/tests/thread-map.c               |  2 +-
> >  tools/perf/util/bpf-filter.c                |  2 +-
> >  tools/perf/util/evlist.c                    |  3 +-
> >  tools/perf/util/parse-events.c              | 33 ++++++++-----
> >  tools/perf/util/parse-events.h              |  1 +
> >  tools/perf/util/python.c                    | 10 ++--
> >  tools/perf/util/target.c                    | 54 +++------------------
> >  tools/perf/util/target.h                    | 15 ++----
> >  tools/perf/util/thread_map.c                | 32 ++----------
> >  tools/perf/util/thread_map.h                |  6 +--
> >  tools/perf/util/top.c                       |  4 +-
> >  tools/perf/util/top.h                       |  1 +
> >  31 files changed, 150 insertions(+), 182 deletions(-)
> >
> > --
> > 2.49.0.850.g28803427d3-goog
> >