From 4aadde89d81fbf4cf3105a61dbc48888b819ecfb Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Tue, 8 Oct 2024 21:07:14 -0400 Subject: [PATCH] tracing/bpf: disable preemption in syscall probe 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. Cc: Michael Jeanson Cc: Masami Hiramatsu Cc: Peter Zijlstra Cc: Alexei Starovoitov Cc: Yonghong Song Cc: Paul E. McKenney Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Mark Rutland Cc: Alexander Shishkin Cc: Namhyung Kim Cc: Andrii Nakryiko Cc: bpf@vger.kernel.org Cc: Joel Fernandes Link: https://lore.kernel.org/20241009010718.2050182-5-mathieu.desnoyers@efficios.com Acked-by: Andrii Nakryiko Tested-by: Andrii Nakryiko # BPF parts Signed-off-by: Mathieu Desnoyers Signed-off-by: Steven Rostedt (Google) --- include/trace/bpf_probe.h | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h index c85bbce5aaa5..fec97c93e1c9 100644 --- a/include/trace/bpf_probe.h +++ b/include/trace/bpf_probe.h @@ -53,8 +53,18 @@ __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) \ +{ \ + preempt_disable_notrace(); \ + CONCATENATE(bpf_trace_run, COUNT_ARGS(args))(__data, CAST_TO_U64(args)); \ + preempt_enable_notrace(); \ +} + #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 -- 2.50.1