linux-kernel - [PATCH v3 0/8] tracing: Allow system call tracepoints to handle page faults

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Message-Id: <20241004145818.1726671-1-mathieu.desnoyers@efficios.com>
Date: Fri,  4 Oct 2024 10:58:10 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To: Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>
Cc: linux-kernel@...r.kernel.org,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	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>,
	Andrii Nakryiko <andrii.nakryiko@...il.com>,
	bpf@...r.kernel.org,
	Joel Fernandes <joel@...lfernandes.org>,
	linux-trace-kernel@...r.kernel.org
Subject: [PATCH v3 0/8] tracing: Allow system call tracepoints to handle page faults

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.

The eBPF people have been needing this feature for quite a while:
https://lore.kernel.org/lkml/c323bce9-a04e-b1c3-580a-783fde259d60@fb.com/

This series replaces the "Faultable Tracepoints v6" series found at [1].

This has been rebased on v6.12-rc1 on top of two patches from Steven:

tracing: Remove definition of trace_*_rcuidle()
tracepoint: Remove SRCU protection

The main change since v2 is removal of remapping from
trace_sys_enter/exit to trace_syscall_sys_enter/exit (likewise for
register/unregister), which caused arch-specific code churn needlessly.

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      | 65 +++++++++++++++++++++++++--------
 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/trace/trace_syscalls.c   | 28 ++++++++++++++
 8 files changed, 196 insertions(+), 24 deletions(-)

-- 
2.39.2