[PATCH v2 4/5] print: use new #[export] macro for rust_fmt_argument

Alice Ryhl
2025-02-28T12:40:15Z

This moves the rust_fmt_argument function over to use the new #[export]
macro, which will verify at compile-time that the function signature
matches what is in the header file.

Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
I'm not sure which header file to put this in. Any advice?
---
include/linux/sprintf.h | 3 +++
lib/vsprintf.c | 3 ---
rust/kernel/print.rs | 3 ++-
3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/linux/sprintf.h b/include/linux/sprintf.h
index 33dcbec71925..029ad83efd74 100644
--- a/include/linux/sprintf.h
+++ b/include/linux/sprintf.h
@@ -24,4 +24,7 @@ __scanf(2, 0) int vsscanf(const char *, const char *, va_list);
extern bool no_hash_pointers;
int no_hash_pointers_enable(char *str);

+/* Used for Rust formatting ('%pA'). */
+char *rust_fmt_argument(char *buf, char *end, const void *ptr);
+
#endif /* _LINUX_KERNEL_SPRINTF_H */
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index a8ac4c4fffcf..1da61c3e011f 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2284,9 +2284,6 @@ int __init no_hash_pointers_enable(char *str)
}
early_param("no_hash_pointers", no_hash_pointers_enable);

-/* Used for Rust formatting ('%pA'). */
-char *rust_fmt_argument(char *buf, char *end, const void *ptr);
-
/*
* Show a '%p' thing. A kernel extension is that the '%p' is followed
* by an extra set of alphanumeric characters that are extended format
diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs
index 61ee36c5e5f5..cf4714242e14 100644
--- a/rust/kernel/print.rs
+++ b/rust/kernel/print.rs
@@ -8,13 +8,14 @@

use crate::{
ffi::{c_char, c_void},
+ prelude::*,
str::RawFormatter,
};
use core::fmt;

// Called from `vsprintf` with format specifier `%pA`.
#[expect(clippy::missing_safety_doc)]
-#[no_mangle]
+#[export]
unsafe extern "C" fn rust_fmt_argument(
buf: *mut c_char,
end: *mut c_char,

--
2.48.1.711.g2feabab25a-goog