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Peter Anvin" , "Peter Zijlstra (Intel)" , Sean Christopherson , Uros Bizjak , Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Mark Rutland , Ryan Roberts , Fuad Tabba , linux-arm-kernel@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Andrew Jones , Alexandre Ghiti , Conor Dooley , Samuel Holland , linux-riscv@lists.infradead.org, Huacai Chen , WANG Xuerui , Bibo Mao , Tiezhu Yang , Andrew Morton , Tianrui Zhao , loongarch@lists.linux.dev, Alice Ryhl X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240628_062414_027991_9A0B8CB7 X-CRM114-Status: GOOD ( 23.85 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org 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 | 12 +++++++++++ rust/bindings/bindings_helper.h | 1 + rust/kernel/lib.rs | 1 + rust/kernel/tracepoint.rs | 47 +++++++++++++++++++++++++++++++++++++++++ 5 files changed, 78 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..08ed5ce63a96 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 @@ -129,6 +136,11 @@ # undef UNDEF_TRACE_INCLUDE_PATH #endif +#ifdef CREATE_RUST_TRACE_POINTS +# undef DEFINE_RUST_DO_TRACE +# define DEFINE_RUST_DO_TRACE(name, proto, args) +#endif + /* We may be processing more files */ #define CREATE_TRACE_POINTS 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 fffd4e1dd1c1..9ae90eb69020 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -46,6 +46,7 @@ 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;