[PATCH v8 3/5] rust: samples: add tracepoint to Rust sample

Alice Ryhl
2024-08-22T12:04:58Z

This updates the Rust printing sample to invoke a tracepoint. This
ensures that we have a user in-tree from the get-go even though the
patch is being merged before its real user.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
MAINTAINERS | 1 +
include/trace/events/rust_sample.h | 31 +++++++++++++++++++++++++++++++
rust/bindings/bindings_helper.h | 1 +
samples/rust/Makefile | 3 ++-
samples/rust/rust_print.rs | 18 ++++++++++++++++++
samples/rust/rust_print_events.c | 8 ++++++++
6 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index f328373463b0..1acf5bfddfc4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19922,6 +19922,7 @@ C: zulip://rust-for-linux.zulipchat.com
P: https://rust-for-linux.com/contributing
T: git https://github.com/Rust-for-Linux/linux.git rust-next
F: Documentation/rust/
+F: include/trace/events/rust_sample.h
F: rust/
F: samples/rust/
F: scripts/*rust*
diff --git a/include/trace/events/rust_sample.h b/include/trace/events/rust_sample.h
new file mode 100644
index 000000000000..dbc80ca2e465
--- /dev/null
+++ b/include/trace/events/rust_sample.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Tracepoints for `samples/rust/rust_print.rs`.
+ *
+ * Copyright (C) 2024 Google, Inc.
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM rust_sample
+
+#if !defined(_RUST_SAMPLE_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _RUST_SAMPLE_TRACE_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(rust_sample_loaded,
+ TP_PROTO(int magic_number),
+ TP_ARGS(magic_number),
+ TP_STRUCT__entry(
+ __field(int, magic_number)
+ ),
+ TP_fast_assign(
+ __entry->magic_number = magic_number;
+ ),
+ TP_printk("magic=%d", __entry->magic_number)
+);
+
+#endif /* _RUST_SAMPLE_TRACE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index fc6f94729789..fe97256afe65 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -23,6 +23,7 @@
#include <linux/tracepoint.h>
#include <linux/wait.h>
#include <linux/workqueue.h>
+#include <trace/events/rust_sample.h>

/* `bindgen` gets confused at certain things. */
const size_t RUST_CONST_HELPER_ARCH_SLAB_MINALIGN = ARCH_SLAB_MINALIGN;
diff --git a/samples/rust/Makefile b/samples/rust/Makefile
index 03086dabbea4..f29280ec4820 100644
--- a/samples/rust/Makefile
+++ b/samples/rust/Makefile
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
+ccflags-y += -I$(src) # needed for trace events

obj-$(CONFIG_SAMPLE_RUST_MINIMAL) += rust_minimal.o
-obj-$(CONFIG_SAMPLE_RUST_PRINT) += rust_print.o
+obj-$(CONFIG_SAMPLE_RUST_PRINT) += rust_print.o rust_print_events.o

subdir-$(CONFIG_SAMPLE_RUST_HOSTPROGS) += hostprogs
diff --git a/samples/rust/rust_print.rs b/samples/rust/rust_print.rs
index 6eabb0d79ea3..6d14b08cac1c 100644
--- a/samples/rust/rust_print.rs
+++ b/samples/rust/rust_print.rs
@@ -69,6 +69,8 @@ fn init(_module: &'static ThisModule) -> Result<Self> {

arc_print()?;

+ trace::trace_rust_sample_loaded(42);
+
Ok(RustPrint)
}
}
@@ -78,3 +80,19 @@ fn drop(&mut self) {
pr_info!("Rust printing macros sample (exit)\n");
}
}
+
+mod trace {
+ use core::ffi::c_int;
+
+ kernel::declare_trace! {
+ /// # Safety
+ ///
+ /// Always safe to call.
+ unsafe fn rust_sample_loaded(magic: c_int);
+ }
+
+ pub(crate) fn trace_rust_sample_loaded(magic: i32) {
+ // SAFETY: Always safe to call.
+ unsafe { rust_sample_loaded(magic as c_int) }
+ }
+}
diff --git a/samples/rust/rust_print_events.c b/samples/rust/rust_print_events.c
new file mode 100644
index 000000000000..a9169ff0edf1
--- /dev/null
+++ b/samples/rust/rust_print_events.c
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2024 Google LLC
+ */
+
+#define CREATE_TRACE_POINTS
+#define CREATE_RUST_TRACE_POINTS
+#include <trace/events/rust_sample.h>

--
2.46.0.184.g6999bdac58-goog