From: Thomas Bertschinger <tahbertschinger@gmail.com>
To: rust-for-linux@vger.kernel.org, ojeda@kernel.org,
alex.gaynor@gmail.com, wedsonaf@gmail.com
Cc: Thomas Bertschinger <tahbertschinger@gmail.com>
Subject: [PATCH] rust: place generated init_module() function in .init.text
Date: Sat, 3 Feb 2024 11:27:35 -0700 [thread overview]
Message-ID: <20240203182735.295946-1-tahbertschinger@gmail.com> (raw)
Currently Rust kernel modules have their init code placed in the `.text`
section of the .ko file. I don't think this causes any real problems
for Rust modules but it does present a challenge with implementing Rust
functionality for existing C modules.
If a Rust `init_module()` function (that lives in `.text`) calls a C
function annotated with `__init`, then a warning is generated because
the C function lives in `.init.text`.
I ran into this while experimenting with converting the bcachefs kernel
module from C to Rust. The module's `init()`, written in Rust, calls C
functions like `bch2_vfs_init()` which are placed in the `.init.text`
section.
This patch places the macro-generated `init_module()` Rust function in
the `.init.text` section.
Note that this is not enough on its own to actually get all the module
initialization code in that section. The module author must still add
the `#[link_section = ".init.text"]` attribute to the Rust `init()` in
the `impl kernel::Module` block in order to then call C `__init`
functions. However, this patch enables module authors do so, when
previously it would not be possible (without warnings).
Signed-off-by: Thomas Bertschinger <tahbertschinger@gmail.com>
---
rust/macros/module.rs | 1 +
1 file changed, 1 insertion(+)
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index d62d8710d77a..d09be1bee397 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -225,6 +225,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
#[cfg(MODULE)]
#[doc(hidden)]
#[no_mangle]
+ #[link_section = \".init.text\"]
pub extern \"C\" fn init_module() -> core::ffi::c_int {{
__init()
}}
--
2.43.0
next reply other threads:[~2024-02-03 18:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-03 18:27 Thomas Bertschinger [this message]
2024-02-03 18:50 ` [PATCH] rust: place generated init_module() function in .init.text Martin Rodriguez Reboredo
2024-02-03 20:26 ` Thomas Bertschinger
2024-02-05 9:45 ` Alice Ryhl
2024-02-05 14:46 ` Thomas Bertschinger
2024-02-05 14:48 ` Alice Ryhl
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