| Message ID | 20240822-tracepoint-v8-2-f0c5899e6fd3@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Tracepoints and static branch in Rust | expand |
On Thu, Aug 22, 2024 at 12:04:14PM +0000, Alice Ryhl wrote: > 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. > > Instead of calling __DO_TRACE directly, the exported rust_do_trace_ > function calls an inline helper function. This is because the `cond` > argument does not exist at the callsite of DEFINE_RUST_DO_TRACE. > > __DECLARE_TRACE always emits an inline static and an extern declaration > that is only used when CREATE_RUST_TRACE_POINTS is set. These should not > end up in the final binary so it is not a problem that they sometimes > are emitted without a user. > > Reviewed-by: Carlos Llamas <cmllamas@google.com> > Reviewed-by: Gary Guo <gary@garyguo.net> > Signed-off-by: Alice Ryhl <aliceryhl@google.com> Reviewed-by: Boqun Feng <boqun.feng@gmail.com> Regards, Boqun > --- > include/linux/tracepoint.h | 22 +++++++++++++++++- > include/trace/define_trace.h | 12 ++++++++++ > rust/bindings/bindings_helper.h | 1 + > rust/kernel/lib.rs | 1 + > rust/kernel/tracepoint.rs | 49 +++++++++++++++++++++++++++++++++++++++++ > 5 files changed, 84 insertions(+), 1 deletion(-) > > diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h > index 6be396bb4297..5042ca588e41 100644 > --- a/include/linux/tracepoint.h > +++ b/include/linux/tracepoint.h > @@ -237,6 +237,18 @@ 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(name, proto, args) \ > + notrace void rust_do_trace_##name(proto) \ > + { \ > + __rust_do_trace_##name(args); \ > + } > + > /* > * Make sure the alignment of the structure in the __tracepoints section will > * not add unwanted padding between the beginning of the section and the > @@ -252,6 +264,13 @@ 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 __rust_do_trace_##name(proto) \ > + { \ > + __DO_TRACE(name, \ > + TP_ARGS(args), \ > + TP_CONDITION(cond), 0); \ > + } \ > static inline void trace_##name(proto) \ > { \ > if (static_key_false(&__tracepoint_##name.key)) \ > @@ -336,7 +355,8 @@ 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..8159294c2041 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(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 8fd092e1b809..fc6f94729789 100644 > --- a/rust/bindings/bindings_helper.h > +++ b/rust/bindings/bindings_helper.h > @@ -20,6 +20,7 @@ > #include <linux/refcount.h> > #include <linux/sched.h> > #include <linux/slab.h> > +#include <linux/tracepoint.h> > #include <linux/wait.h> > #include <linux/workqueue.h> > > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs > index 91af9f75d121..d00a44b000b6 100644 > --- a/rust/kernel/lib.rs > +++ b/rust/kernel/lib.rs > @@ -51,6 +51,7 @@ > pub mod sync; > pub mod task; > pub mod time; > +pub mod tracepoint; > pub mod types; > pub mod uaccess; > pub mod workqueue; > diff --git a/rust/kernel/tracepoint.rs b/rust/kernel/tracepoint.rs > new file mode 100644 > index 000000000000..cf2d9ad15912 > --- /dev/null > +++ b/rust/kernel/tracepoint.rs > @@ -0,0 +1,49 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +// Copyright (C) 2024 Google LLC. > + > +//! Logic for tracepoints. > + > +/// Declare the Rust entry point for a tracepoint. > +/// > +/// This macro generates an unsafe function that calls into C, and its safety requirements will be > +/// whatever the relevant C code requires. To document these safety requirements, you may add > +/// doc-comments when invoking the macro. > +#[macro_export] > +macro_rules! declare_trace { > + ($($(#[$attr:meta])* $pub:vis unsafe fn $name:ident($($argname:ident : $argtyp:ty),* $(,)?);)*) => {$( > + $( #[$attr] )* > + #[inline(always)] > + $pub unsafe fn $name($($argname : $argtyp),*) { > + #[cfg(CONFIG_TRACEPOINTS)] > + { > + // SAFETY: It's always okay to query the static key for a tracepoint. > + let should_trace = unsafe { > + $crate::macros::paste! { > + $crate::jump_label::static_key_false!( > + $crate::bindings::[< __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 { $crate::bindings::[< 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; > > -- > 2.46.0.184.g6999bdac58-goog >
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h index 6be396bb4297..5042ca588e41 100644 --- a/include/linux/tracepoint.h +++ b/include/linux/tracepoint.h @@ -237,6 +237,18 @@ 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(name, proto, args) \ + notrace void rust_do_trace_##name(proto) \ + { \ + __rust_do_trace_##name(args); \ + } + /* * Make sure the alignment of the structure in the __tracepoints section will * not add unwanted padding between the beginning of the section and the @@ -252,6 +264,13 @@ 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 __rust_do_trace_##name(proto) \ + { \ + __DO_TRACE(name, \ + TP_ARGS(args), \ + TP_CONDITION(cond), 0); \ + } \ static inline void trace_##name(proto) \ { \ if (static_key_false(&__tracepoint_##name.key)) \ @@ -336,7 +355,8 @@ 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..8159294c2041 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(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 8fd092e1b809..fc6f94729789 100644 --- a/rust/bindings/bindings_helper.h +++ b/rust/bindings/bindings_helper.h @@ -20,6 +20,7 @@ #include <linux/refcount.h> #include <linux/sched.h> #include <linux/slab.h> +#include <linux/tracepoint.h> #include <linux/wait.h> #include <linux/workqueue.h> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 91af9f75d121..d00a44b000b6 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -51,6 +51,7 @@ pub mod sync; pub mod task; pub mod time; +pub mod tracepoint; pub mod types; pub mod uaccess; pub mod workqueue; diff --git a/rust/kernel/tracepoint.rs b/rust/kernel/tracepoint.rs new file mode 100644 index 000000000000..cf2d9ad15912 --- /dev/null +++ b/rust/kernel/tracepoint.rs @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 + +// Copyright (C) 2024 Google LLC. + +//! Logic for tracepoints. + +/// Declare the Rust entry point for a tracepoint. +/// +/// This macro generates an unsafe function that calls into C, and its safety requirements will be +/// whatever the relevant C code requires. To document these safety requirements, you may add +/// doc-comments when invoking the macro. +#[macro_export] +macro_rules! declare_trace { + ($($(#[$attr:meta])* $pub:vis unsafe fn $name:ident($($argname:ident : $argtyp:ty),* $(,)?);)*) => {$( + $( #[$attr] )* + #[inline(always)] + $pub unsafe fn $name($($argname : $argtyp),*) { + #[cfg(CONFIG_TRACEPOINTS)] + { + // SAFETY: It's always okay to query the static key for a tracepoint. + let should_trace = unsafe { + $crate::macros::paste! { + $crate::jump_label::static_key_false!( + $crate::bindings::[< __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 { $crate::bindings::[< 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;