From b0e28a4b5becea84ae6fca5cbd8a6b80a134e223 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 18 Apr 2024 12:09:08 -0700 Subject: ftrace: make extra rcu_is_watching() validation check optional Introduce CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING config option to control whether ftrace low-level code performs additional rcu_is_watching()-based validation logic in an attempt to catch noinstr violations. This check is expected to never be true and is mostly useful for low-level validation of ftrace subsystem invariants. For most users it should probably be kept disabled to eliminate unnecessary runtime overhead. This improves BPF multi-kretprobe (relying on ftrace and rethook infrastructure) runtime throughput by 2%, according to BPF benchmarks ([0]). [0] https://lore.kernel.org/bpf/CAEf4BzauQ2WKMjZdc9s0rBWa01BYbgwHN6aNDXQSHYia47pQ-w@mail.gmail.com/ Link: https://lore.kernel.org/all/20240418190909.704286-1-andrii@kernel.org/ Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: Paul E. McKenney Acked-by: Masami Hiramatsu (Google) Signed-off-by: Andrii Nakryiko Signed-off-by: Masami Hiramatsu (Google) --- include/linux/trace_recursion.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/trace_recursion.h') diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h index d48cd92d2364..24ea8ac049b4 100644 --- a/include/linux/trace_recursion.h +++ b/include/linux/trace_recursion.h @@ -135,7 +135,7 @@ extern void ftrace_record_recursion(unsigned long ip, unsigned long parent_ip); # define do_ftrace_record_recursion(ip, pip) do { } while (0) #endif -#ifdef CONFIG_ARCH_WANTS_NO_INSTR +#ifdef CONFIG_FTRACE_VALIDATE_RCU_IS_WATCHING # define trace_warn_on_no_rcu(ip) \ ({ \ bool __ret = !rcu_is_watching(); \ -- cgit v1.2.3-59-g8ed1b