Wire up the system call tracepoints with Tasks Trace RCU to allow
the ftrace, perf, and eBPF tracers to handle page faults.

This series does the initial wire-up allowing tracers to handle page
faults, but leaves out the actual handling of said page faults as future
work.

I have tested this against a feature branch of lttng-modules which
implements handling of page faults for the filename argument of the
openat(2) system call.

This v5 addresses comments from the previous round of review [1].

Steven Rostedt suggested separating tracepoints into two separate
sections. It is unclear how that approach would prove to be an
improvement over the currently proposed approach, so those changes were
not incorporated. See [2] for my detailed reply.

In the previous round, Peter Zijlstra suggested use of SRCU rather than
Tasks Trace RCU. See my reply about the distinction between SRCU and
Tasks Trace RCU [3] and this explanation from Paul E. McKenney about the
purpose of Tasks Trace RCU [4].

The macros DEFINE_INACTIVE_GUARD and activate_guard are added to
cleanup.h for use in the __DO_TRACE() macro. Those appear to be more
flexible than the guard_if() proposed by Peter Zijlstra in the previous
round of review [5].

This series is based on kernel v6.9.6.

Thanks,

Mathieu

Link: https://lore.kernel.org/lkml/20231120205418.334172-1-mathieu.desnoyers@efficios.com/ # [1]
Link: https://lore.kernel.org/lkml/e4e9a2bc-1776-4b51-aba4-a147795a5de1@efficios.com/ # [2]
Link: https://lore.kernel.org/lkml/a0ac5f77-411e-4562-9863-81196238f3f5@efficios.com/ # [3]
Link: https://lore.kernel.org/lkml/ba543d44-9302-4115-ac4f-d4e9f8d98a90@paulmck-laptop/ # [4]
Link: https://lore.kernel.org/lkml/20231120221524.GD8262@noisy.programming.kicks-ass.net/ # [5]
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: bpf@vger.kernel.org
Cc: Joel Fernandes <joel@joelfernandes.org>

Mathieu Desnoyers (8):
  cleanup.h: Header include guard should match header name
  cleanup.h guard: Rename DEFINE_ prefix to DECLARE_
  cleanup.h: Introduce DEFINE_INACTIVE_GUARD and activate_guard
  tracing: Introduce faultable tracepoints
  tracing/ftrace: Add support for faultable tracepoints
  tracing/bpf-trace: Add support for faultable tracepoints
  tracing/perf: Add support for faultable tracepoints
  tracing: Convert sys_enter/exit to faultable tracepoints

 drivers/cxl/core/cdat.c                     |  2 +-
 drivers/cxl/cxl.h                           |  2 +-
 drivers/gpio/gpiolib.h                      |  2 +-
 drivers/platform/x86/intel/pmc/core_ssram.c |  2 +-
 fs/fuse/virtio_fs.c                         |  2 +-
 fs/pstore/inode.c                           |  4 +-
 include/linux/bitmap.h                      |  2 +-
 include/linux/cleanup.h                     | 85 ++++++++++++--------
 include/linux/cpu.h                         |  2 +-
 include/linux/cpumask.h                     |  2 +-
 include/linux/device.h                      |  6 +-
 include/linux/file.h                        |  4 +-
 include/linux/firmware.h                    |  2 +-
 include/linux/gpio/driver.h                 |  4 +-
 include/linux/iio/iio.h                     |  4 +-
 include/linux/irqflags.h                    |  4 +-
 include/linux/mutex.h                       |  6 +-
 include/linux/of.h                          |  2 +-
 include/linux/pci.h                         |  4 +-
 include/linux/percpu.h                      |  2 +-
 include/linux/preempt.h                     |  6 +-
 include/linux/rcupdate.h                    |  2 +-
 include/linux/rwsem.h                       | 10 +--
 include/linux/sched/task.h                  |  4 +-
 include/linux/slab.h                        |  4 +-
 include/linux/spinlock.h                    | 38 ++++-----
 include/linux/srcu.h                        |  2 +-
 include/linux/tracepoint-defs.h             | 14 ++++
 include/linux/tracepoint.h                  | 88 +++++++++++++++------
 include/sound/pcm.h                         |  6 +-
 include/trace/bpf_probe.h                   | 20 ++++-
 include/trace/define_trace.h                |  7 ++
 include/trace/events/syscalls.h             |  4 +-
 include/trace/perf.h                        | 22 +++++-
 include/trace/trace_events.h                | 68 +++++++++++++++-
 init/Kconfig                                |  1 +
 kernel/sched/core.c                         |  4 +-
 kernel/sched/sched.h                        | 16 ++--
 kernel/trace/bpf_trace.c                    | 11 ++-
 kernel/trace/trace_events.c                 | 28 +++++--
 kernel/trace/trace_fprobe.c                 |  5 +-
 kernel/trace/trace_syscalls.c               | 52 ++++++++++--
 kernel/tracepoint.c                         | 65 +++++++++------
 lib/locking-selftest.c                      | 12 +--
 sound/core/control_led.c                    |  2 +-
 45 files changed, 441 insertions(+), 193 deletions(-)

-- 
2.39.2

On Wed, 26 Jun 2024 14:59:33 -0400
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> Wire up the system call tracepoints with Tasks Trace RCU to allow
> the ftrace, perf, and eBPF tracers to handle page faults.
> 
> This series does the initial wire-up allowing tracers to handle page
> faults, but leaves out the actual handling of said page faults as future
> work.
> 
> I have tested this against a feature branch of lttng-modules which
> implements handling of page faults for the filename argument of the
> openat(2) system call.
> 
> This v5 addresses comments from the previous round of review [1].

Hi Mathieu,

Can you resend this and Cc linux-trace-kernel@vger.kernel.org?

That would put it into our patchwork and makes it work with our workflow.

 https://patchwork.kernel.org/project/linux-trace-kernel/list/

Thanks,

-- Steve


> 
> Steven Rostedt suggested separating tracepoints into two separate
> sections. It is unclear how that approach would prove to be an
> improvement over the currently proposed approach, so those changes were
> not incorporated. See [2] for my detailed reply.
> 
> In the previous round, Peter Zijlstra suggested use of SRCU rather than
> Tasks Trace RCU. See my reply about the distinction between SRCU and
> Tasks Trace RCU [3] and this explanation from Paul E. McKenney about the
> purpose of Tasks Trace RCU [4].
> 
> The macros DEFINE_INACTIVE_GUARD and activate_guard are added to
> cleanup.h for use in the __DO_TRACE() macro. Those appear to be more
> flexible than the guard_if() proposed by Peter Zijlstra in the previous
> round of review [5].
> 
> This series is based on kernel v6.9.6.

On 2024-06-27 03:25, Steven Rostedt wrote:
> On Wed, 26 Jun 2024 14:59:33 -0400
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> 
>> Wire up the system call tracepoints with Tasks Trace RCU to allow
>> the ftrace, perf, and eBPF tracers to handle page faults.
>>
>> This series does the initial wire-up allowing tracers to handle page
>> faults, but leaves out the actual handling of said page faults as future
>> work.
>>
>> I have tested this against a feature branch of lttng-modules which
>> implements handling of page faults for the filename argument of the
>> openat(2) system call.
>>
>> This v5 addresses comments from the previous round of review [1].
> 
> Hi Mathieu,
> 
> Can you resend this and Cc linux-trace-kernel@vger.kernel.org?

Sure, will do for v6. Thanks!

Mathieu

> 
> That would put it into our patchwork and makes it work with our workflow.
> 
>   https://patchwork.kernel.org/project/linux-trace-kernel/list/
> 
> Thanks,
> 
> -- Steve
> 
> 
>>
>> Steven Rostedt suggested separating tracepoints into two separate
>> sections. It is unclear how that approach would prove to be an
>> improvement over the currently proposed approach, so those changes were
>> not incorporated. See [2] for my detailed reply.
>>
>> In the previous round, Peter Zijlstra suggested use of SRCU rather than
>> Tasks Trace RCU. See my reply about the distinction between SRCU and
>> Tasks Trace RCU [3] and this explanation from Paul E. McKenney about the
>> purpose of Tasks Trace RCU [4].
>>
>> The macros DEFINE_INACTIVE_GUARD and activate_guard are added to
>> cleanup.h for use in the __DO_TRACE() macro. Those appear to be more
>> flexible than the guard_if() proposed by Peter Zijlstra in the previous
>> round of review [5].
>>
>> This series is based on kernel v6.9.6.

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com