linux-kernel - [RFC PATCH 0/6] Sleepable tracepoints

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Date:   Fri, 23 Oct 2020 15:53:46 -0400
From:   Michael Jeanson <mjeanson@...icios.com>
To:     linux-kernel@...r.kernel.org
Cc:     mathieu.desnoyers@...icios.com,
        Michael Jeanson <mjeanson@...icios.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Yonghong Song <yhs@...com>,
        "Paul E . McKenney" <paulmck@...nel.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@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>, bpf@...r.kernel.org
Subject: [RFC PATCH 0/6] Sleepable tracepoints

When invoked from system call enter/exit instrumentation, accessing
user-space data is a common use-case for tracers. However, tracepoints
currently disable preemption around iteration on the registered
tracepoint probes and invocation of the probe callbacks, which prevents
tracers from handling page faults.

Extend the tracepoint and trace event APIs to allow specific tracer
probes to take page faults. Adapt ftrace, perf, and ebpf to allow being
called from sleepable context, and convert the system call enter/exit
instrumentation to sleepable tracepoints.

This series only implements the tracepoint infrastructure required to
allow tracers to handle page faults. Modifying each tracer to handle
those page faults would be a next step after we all agree on this piece
of instrumentation infrastructure.

This patchset is base on v5.9.1.

Cc: Steven Rostedt (VMware) <rostedt@...dmis.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Yonghong Song <yhs@...com>
Cc: Paul E. McKenney <paulmck@...nel.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Joel Fernandes (Google) <joel@...lfernandes.org>
Cc: bpf@...r.kernel.org

Mathieu Desnoyers (1):
  tracing: use sched-RCU instead of SRCU for rcuidle tracepoints

Michael Jeanson (5):
  tracing: introduce sleepable tracepoints
  tracing: ftrace: add support for sleepable tracepoints
  tracing: bpf-trace: add support for sleepable tracepoints
  tracing: perf: add support for sleepable tracepoints
  tracing: convert sys_enter/exit to sleepable tracepoints

 include/linux/tracepoint-defs.h |  11 ++++
 include/linux/tracepoint.h      | 104 +++++++++++++++++++++-----------
 include/trace/bpf_probe.h       |  23 ++++++-
 include/trace/define_trace.h    |   7 +++
 include/trace/events/syscalls.h |   4 +-
 include/trace/perf.h            |  26 ++++++--
 include/trace/trace_events.h    |  79 ++++++++++++++++++++++--
 init/Kconfig                    |   1 +
 kernel/trace/bpf_trace.c        |   5 +-
 kernel/trace/trace_events.c     |  15 ++++-
 kernel/trace/trace_syscalls.c   |  68 +++++++++++++--------
 kernel/tracepoint.c             | 104 +++++++++++++++++++++++++-------
 12 files changed, 351 insertions(+), 96 deletions(-)

-- 
2.25.1