On Thu, Jun 06, 2024 at 11:30:03AM -0400, Mathieu Desnoyers wrote:
On 2024-06-06 11:05, 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.
Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
[...]
diff --git a/rust/helpers.c b/rust/helpers.c
index 2c37a0f5d7a8..0560cc2a512a 100644
--- a/rust/helpers.c
+++ b/rust/helpers.c
@@ -165,6 +165,30 @@ rust_helper_krealloc(const void *objp, size_t new_size, gfp_t flags)
}
EXPORT_SYMBOL_GPL(rust_helper_krealloc);
+void rust_helper_preempt_enable_notrace(void)
+{
+ preempt_enable_notrace();
+}
+EXPORT_SYMBOL_GPL(rust_helper_preempt_enable_notrace);
+
+void rust_helper_preempt_disable_notrace(void)
+{
+ preempt_disable_notrace();
+}
+EXPORT_SYMBOL_GPL(rust_helper_preempt_disable_notrace);
+
+bool rust_helper_current_cpu_online(void)
+{
+ return cpu_online(raw_smp_processor_id());
+}
+EXPORT_SYMBOL_GPL(rust_helper_current_cpu_online);
+
+void *rust_helper___rcu_dereference_raw(void **p)
+{
+ return rcu_dereference_raw(p);
+}
+EXPORT_SYMBOL_GPL(rust_helper___rcu_dereference_raw);
Ouch. Doing a function call for each of those small operations will
have a rather large performance impact when tracing is active. If it is
Long-term plan is to 1) compile the C helpers in some IR and 2) inline
the helpers with Rust in IR-level, as what Gary has:
https://lore.kernel.org/rust-for-linux/20240529202817.3641974-1-gary@xxxxxxxxxxx/
and I use it for the upcoming atomic API support:
https://github.com/fbq/linux/tree/dev/rust/atomic-rfc
and it works very well.
Regards,
Boqun
not possible to inline those in Rust, then implementing __DO_TRACE in
a C function would at least allow Rust to only do a single call to C
rather than go back and forth between Rust and C.
What prevents inlining those helpers in Rust ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com