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Mon, 10 Jun 2024 07:01:50 -0700 (PDT) Date: Mon, 10 Jun 2024 14:01:05 +0000 In-Reply-To: <20240610-tracepoint-v2-0-faebad81b355@google.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240610-tracepoint-v2-0-faebad81b355@google.com> X-Developer-Key: i=aliceryhl@google.com; a=openpgp; fpr=49F6C1FAA74960F43A5B86A1EE7A392FDE96209F X-Developer-Signature: v=1; a=openpgp-sha256; l=5679; i=aliceryhl@google.com; h=from:subject:message-id; bh=Cbr/oyqLs30l5kHzPHIKBFw+7ijjcP/soSV8d5bF/6c=; b=owEBbQKS/ZANAwAKAQRYvu5YxjlGAcsmYgBmZwdFyoZES6wUnB8a6HfkMMvV3cAI2deGLmDYw YjVBlpZV9SJAjMEAAEKAB0WIQSDkqKUTWQHCvFIvbIEWL7uWMY5RgUCZmcHRQAKCRAEWL7uWMY5 RgKLD/99q9BaDPXlZi93F4HrhWiyx3jSWWiL3FlVntMFmRjh30wfOBLJwSneVkTvLDr/UONVh6p LgRKlhQfXVYFHK3JFfYbEXSonuGFWkaRFPF0A+i3XuYUosnS+LxNcHv0md16126nUtrhtEyMgr4 1B+m6thCprxdnJU8KofRtFvz2cRAP9Z2KPVorFBL7libs3XRcJfO9HHaYYcqT0hSm/MzLvq9OBt AzNIa1ZZD8AvNn+vnKjZr6wvpJmJ5ljiXTUskTc/qQ4eyho0izkoHRMMhqanxI3G8LMNoXmGUB3 3iP2ZECiFB5tlDP0yKmP6Ee42WcFqrTcVP3y8coiQv9efgKDc9j75g/0F+VXWGSXwpiEA+z5L3h WsovfcZE48Wo6Nk0HxaplalVElXl941R/ZDxDrpyru9Gxisty496fmuy2Era2M3EYq9iVeM67zE RsEJBkAlP08pvJ27sEtl8PwTOtsZI7Jrq1jsWxICXSw62nG1KAAuIMoRAOGg7hQb6Pjmis9ZOns VMtVqXExCcdnki/ribs68aTwAfl6RG4YLLKb6ddtlH9NTvNYVBPZmrJhqFWn8PGZOsQOuU3WrTv NeZYWE3flvevie9DeqTfo1zMKwDvi7Mdtrh8IBC6uskew3ZG3LRkYqckoR9zN8WfVcrCT8+HAv2 7lhMJU9ONZeRPxQ== X-Mailer: b4 0.13-dev-26615 Message-ID: <20240610-tracepoint-v2-2-faebad81b355@google.com> Subject: [PATCH v2 2/2] rust: add tracepoint support From: Alice Ryhl To: Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Peter Zijlstra , Josh Poimboeuf , Jason Baron , Ard Biesheuvel , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , " =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= " , Benno Lossin , Andreas Hindborg Cc: linux-trace-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Alice Ryhl Make it possible to have Rust code call into tracepoints defined by C code. It is still required that the tracepoint is declared in a C header, and that this header is included in the input to bindgen. Signed-off-by: Alice Ryhl --- include/linux/tracepoint.h | 18 +++++++++++++++- include/trace/define_trace.h | 7 ++++++ rust/bindings/bindings_helper.h | 1 + rust/kernel/lib.rs | 1 + rust/kernel/tracepoint.rs | 47 +++++++++++++++++++++++++++++++++++++++++ 5 files changed, 73 insertions(+), 1 deletion(-) diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 689b6d71590e..d82af4d77c9f 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -238,6 +238,20 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) #define __DECLARE_TRACE_RCU(name, proto, args, cond) #endif +/* + * Declare an exported function that Rust code can call to trigger this + * tracepoint. This function does not include the static branch; that is done + * in Rust to avoid a function call when the tracepoint is disabled. + */ +#define DEFINE_RUST_DO_TRACE(name, proto, args) +#define DEFINE_RUST_DO_TRACE_REAL(name, proto, args) \ + notrace void rust_do_trace_##name(proto) \ + { \ + __DO_TRACE(name, \ + TP_ARGS(args), \ + cpu_online(raw_smp_processor_id()), 0); \ + } + /* * Make sure the alignment of the structure in the __tracepoints section will * not add unwanted padding between the beginning of the section and the @@ -253,6 +267,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) extern int __traceiter_##name(data_proto); \ DECLARE_STATIC_CALL(tp_func_##name, __traceiter_##name); \ extern struct tracepoint __tracepoint_##name; \ + extern void rust_do_trace_##name(proto); \ static inline void trace_##name(proto) \ { \ if (static_key_false(&__tracepoint_##name.key)) \ @@ -337,7 +352,8 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p) void __probestub_##_name(void *__data, proto) \ { \ } \ - DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name); + DEFINE_STATIC_CALL(tp_func_##_name, __traceiter_##_name); \ + DEFINE_RUST_DO_TRACE(_name, TP_PROTO(proto), TP_ARGS(args)) #define DEFINE_TRACE(name, proto, args) \ DEFINE_TRACE_FN(name, NULL, NULL, PARAMS(proto), PARAMS(args)); diff --git a/include/trace/define_trace.h b/include/trace/define_trace.h index 00723935dcc7..b47cc036acba 100644 --- a/include/trace/define_trace.h +++ b/include/trace/define_trace.h @@ -72,6 +72,13 @@ #define DECLARE_TRACE(name, proto, args) \ DEFINE_TRACE(name, PARAMS(proto), PARAMS(args)) +/* If requested, create helpers for calling these tracepoints from Rust. */ +#ifdef CREATE_RUST_TRACE_POINTS +#undef DEFINE_RUST_DO_TRACE +#define DEFINE_RUST_DO_TRACE(name, proto, args) \ + DEFINE_RUST_DO_TRACE_REAL(name, PARAMS(proto), PARAMS(args)) +#endif + #undef TRACE_INCLUDE #undef __TRACE_INCLUDE diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h index ddb5644d4fd9..d442f9ccfc2c 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -15,6 +15,7 @@ #include #include #include +#include #include #include diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index a0be9544996d..96f8f11c51f2 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -45,6 +45,7 @@ pub mod sync; pub mod task; pub mod time; +pub mod tracepoint; pub mod types; pub mod workqueue; diff --git a/rust/kernel/tracepoint.rs b/rust/kernel/tracepoint.rs new file mode 100644 index 000000000000..1005f09e0330 --- /dev/null +++ b/rust/kernel/tracepoint.rs @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Logic for tracepoints. + +/// Declare the Rust entry point for a tracepoint. +#[macro_export] +macro_rules! declare_trace { + ($($(#[$attr:meta])* $pub:vis fn $name:ident($($argname:ident : $argtyp:ty),* $(,)?);)*) => {$( + $( #[$attr] )* + #[inline(always)] + $pub unsafe fn $name($($argname : $argtyp),*) { + #[cfg(CONFIG_TRACEPOINTS)] + { + use $crate::bindings::*; + + // SAFETY: It's always okay to query the static key for a tracepoint. + let should_trace = unsafe { + $crate::macros::paste! { + $crate::static_key::static_key_false!( + [< __tracepoint_ $name >], + $crate::bindings::tracepoint, + key + ) + } + }; + + if should_trace { + $crate::macros::paste! { + // SAFETY: The caller guarantees that it is okay to call this tracepoint. + unsafe { [< rust_do_trace_ $name >]($($argname),*) }; + } + } + } + + #[cfg(not(CONFIG_TRACEPOINTS))] + { + // If tracepoints are disabled, insert a trivial use of each argument + // to avoid unused argument warnings. + $( let _unused = $argname; )* + } + } + )*} +} + +pub use declare_trace;