linux-kernel - Re: [PATCH 0/8] tracing: Allow system call tracepoints to handle page faults

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Message-ID: <d294fc4c-45c1-49ec-98e3-5b42b7ab3b4b@efficios.com>
Date: Mon, 9 Sep 2024 20:36:21 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Steven Rostedt <rostedt@...dmis.org>,
 Masami Hiramatsu <mhiramat@...nel.org>, linux-kernel@...r.kernel.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>,
 Namhyung Kim <namhyung@...nel.org>, bpf@...r.kernel.org,
 Joel Fernandes <joel@...lfernandes.org>, linux-trace-kernel@...r.kernel.org
Subject: Re: [PATCH 0/8] tracing: Allow system call tracepoints to handle page
 faults

On 2024-09-09 19:53, Andrii Nakryiko wrote:
> On Mon, Sep 9, 2024 at 1:17 PM Mathieu Desnoyers
> <mathieu.desnoyers@...icios.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.
>>
>> This series was compile and runtime tested with ftrace and perf syscall
>> tracing and raw syscall tracing, adding a WARN_ON_ONCE() in the
>> generated code to validate that the intended probes are used for raw
>> syscall tracing. The might_fault() added within those probes validate
>> that they are called from a context where handling a page fault is OK.
>>
>> For ebpf, this series is compile-tested only.
> 
> What tree/branch was this based on? I can't apply it cleanly anywhere I tried...

This series was based on tag v6.10.6

Sorry I should have included this information in patch 0.

Thanks,

Mathieu

> 
>>
>> This series replaces the "Faultable Tracepoints v6" series found at [1].
>>
>> Thanks,
>>
>> Mathieu
>>
>> Link: https://lore.kernel.org/lkml/20240828144153.829582-1-mathieu.desnoyers@efficios.com/ # [1]
>> 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: Namhyung Kim <namhyung@...nel.org>
>> Cc: Andrii Nakryiko <andrii.nakryiko@...il.com>
>> Cc: bpf@...r.kernel.org
>> Cc: Joel Fernandes <joel@...lfernandes.org>
>> Cc: linux-trace-kernel@...r.kernel.org
>>
>> Mathieu Desnoyers (8):
>>    tracing: Declare system call tracepoints with TRACE_EVENT_SYSCALL
>>    tracing/ftrace: guard syscall probe with preempt_notrace
>>    tracing/perf: guard syscall probe with preempt_notrace
>>    tracing/bpf: guard syscall probe with preempt_notrace
>>    tracing: Allow system call tracepoints to handle page faults
>>    tracing/ftrace: Add might_fault check to syscall probes
>>    tracing/perf: Add might_fault check to syscall probes
>>    tracing/bpf: Add might_fault check to syscall probes
>>
>>   include/linux/tracepoint.h      | 87 +++++++++++++++++++++++++--------
>>   include/trace/bpf_probe.h       | 13 +++++
>>   include/trace/define_trace.h    |  5 ++
>>   include/trace/events/syscalls.h |  4 +-
>>   include/trace/perf.h            | 43 ++++++++++++++--
>>   include/trace/trace_events.h    | 61 +++++++++++++++++++++--
>>   init/Kconfig                    |  1 +
>>   kernel/entry/common.c           |  4 +-
>>   kernel/trace/trace_syscalls.c   | 36 ++++++++++++--
>>   9 files changed, 218 insertions(+), 36 deletions(-)
>>
>> --
>> 2.39.2

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