samples: rust: fix `rust_print` build making it a combined module

The `rust_print` module, when built as a module, fails to build with:

    ERROR: modpost: missing MODULE_LICENSE() in samples/rust/rust_print_events.o
    ERROR: modpost: "__tracepoint_rust_sample_loaded" [samples/rust/rust_print.ko] undefined!
    ERROR: modpost: "rust_do_trace_rust_sample_loaded" [samples/rust/rust_print.ko] undefined!

Fix it by building it as a combined one.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: "Linux Next Mailing List" <linux-next@vger.kernel.org>
Link: https://lore.kernel.org/20241111220805.708889-1-ojeda@kernel.org
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/all/20241108152149.28459a72@canb.auug.org.au/
Fixes: 91d39024e1b0 ("rust: samples: add tracepoint to Rust sample")
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 98 insertions, 0 deletions

diff --git a/samples/rust/rust_print_main.rs b/samples/rust/rust_print_main.rs
new file mode 100644
index 000000000000..6d14b08cac1c
--- /dev/null
+++ b/samples/rust/rust_print_main.rs
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust printing macros sample.
+
+use kernel::pr_cont;
+use kernel::prelude::*;
+
+module! {
+    type: RustPrint,
+    name: "rust_print",
+    author: "Rust for Linux Contributors",
+    description: "Rust printing macros sample",
+    license: "GPL",
+}
+
+struct RustPrint;
+
+fn arc_print() -> Result {
+    use kernel::sync::*;
+
+    let a = Arc::new(1, GFP_KERNEL)?;
+    let b = UniqueArc::new("hello, world", GFP_KERNEL)?;
+
+    // Prints the value of data in `a`.
+    pr_info!("{}", a);
+
+    // Uses ":?" to print debug fmt of `b`.
+    pr_info!("{:?}", b);
+
+    let a: Arc<&str> = b.into();
+    let c = a.clone();
+
+    // Uses `dbg` to print, will move `c` (for temporary debugging purposes).
+    dbg!(c);
+
+    // Pretty-prints the debug formatting with lower-case hexadecimal integers.
+    pr_info!("{:#x?}", a);
+
+    Ok(())
+}
+
+impl kernel::Module for RustPrint {
+    fn init(_module: &'static ThisModule) -> Result<Self> {
+        pr_info!("Rust printing macros sample (init)\n");
+
+        pr_emerg!("Emergency message (level 0) without args\n");
+        pr_alert!("Alert message (level 1) without args\n");
+        pr_crit!("Critical message (level 2) without args\n");
+        pr_err!("Error message (level 3) without args\n");
+        pr_warn!("Warning message (level 4) without args\n");
+        pr_notice!("Notice message (level 5) without args\n");
+        pr_info!("Info message (level 6) without args\n");
+
+        pr_info!("A line that");
+        pr_cont!(" is continued");
+        pr_cont!(" without args\n");
+
+        pr_emerg!("{} message (level {}) with args\n", "Emergency", 0);
+        pr_alert!("{} message (level {}) with args\n", "Alert", 1);
+        pr_crit!("{} message (level {}) with args\n", "Critical", 2);
+        pr_err!("{} message (level {}) with args\n", "Error", 3);
+        pr_warn!("{} message (level {}) with args\n", "Warning", 4);
+        pr_notice!("{} message (level {}) with args\n", "Notice", 5);
+        pr_info!("{} message (level {}) with args\n", "Info", 6);
+
+        pr_info!("A {} that", "line");
+        pr_cont!(" is {}", "continued");
+        pr_cont!(" with {}\n", "args");
+
+        arc_print()?;
+
+        trace::trace_rust_sample_loaded(42);
+
+        Ok(RustPrint)
+    }
+}
+
+impl Drop for RustPrint {
+    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) }
+    }
+}