diff mbox series

[v3,4/8] tracing/bpf: guard syscall probe with preempt_notrace

Message ID 20241004145818.1726671-5-mathieu.desnoyers@efficios.com (mailing list archive)
State Superseded
Headers show
Series tracing: Allow system call tracepoints to handle page faults | expand

Commit Message

Mathieu Desnoyers Oct. 4, 2024, 2:58 p.m. UTC 
In preparation for allowing system call enter/exit instrumentation to
handle page faults, make sure that bpf can handle this change by
explicitly disabling preemption within the bpf system call tracepoint
probes to respect the current expectations within bpf tracing code.

This change does not yet allow bpf to take page faults per se within its
probe, but allows its existing probes to adapt to the upcoming change.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org> # BPF parts
Cc: Michael Jeanson <mjeanson@efficios.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
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: Namhyung Kim <namhyung@kernel.org>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: bpf@vger.kernel.org
Cc: Joel Fernandes <joel@joelfernandes.org>
---
 include/trace/bpf_probe.h | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

Comments

Steven Rostedt Oct. 8, 2024, 11:22 p.m. UTC | #1 
On Fri,  4 Oct 2024 10:58:14 -0400
Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:

> +#define __BPF_DECLARE_TRACE_SYSCALL(call, proto, args)			\
> +static notrace void							\
> +__bpf_trace_##call(void *__data, proto)					\
> +{									\
> +	guard(preempt_notrace)();					\
> +	CONCATENATE(bpf_trace_run, COUNT_ARGS(args))(__data, CAST_TO_U64(args));	\
> +}
> +

Same here for using guard over just adding preempt_disable/enable_notrace().

-- Steve
diff mbox series

Patch

diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h
index c85bbce5aaa5..211b98d45fc6 100644
--- a/include/trace/bpf_probe.h
+++ b/include/trace/bpf_probe.h
@@ -53,8 +53,17 @@  __bpf_trace_##call(void *__data, proto)					\
 #define DECLARE_EVENT_CLASS(call, proto, args, tstruct, assign, print)	\
 	__BPF_DECLARE_TRACE(call, PARAMS(proto), PARAMS(args))
 
+#define __BPF_DECLARE_TRACE_SYSCALL(call, proto, args)			\
+static notrace void							\
+__bpf_trace_##call(void *__data, proto)					\
+{									\
+	guard(preempt_notrace)();					\
+	CONCATENATE(bpf_trace_run, COUNT_ARGS(args))(__data, CAST_TO_U64(args));	\
+}
+
 #undef DECLARE_EVENT_SYSCALL_CLASS
-#define DECLARE_EVENT_SYSCALL_CLASS DECLARE_EVENT_CLASS
+#define DECLARE_EVENT_SYSCALL_CLASS(call, proto, args, tstruct, assign, print)	\
+	__BPF_DECLARE_TRACE_SYSCALL(call, PARAMS(proto), PARAMS(args))
 
 /*
  * This part is compiled out, it is only here as a build time check