Rust has two different tools for generating function declarations to call across the FFI boundary: * bindgen. Generates Rust declarations from a C header. * cbindgen. Generates C headers from Rust declarations. In the kernel, we only use bindgen. This is because cbindgen assumes a cargo-based buildsystem, so it is not compatible with the kernel's build system. This means that when C code calls a Rust function by name, its signature must be duplicated in both Rust code and a C header, and the signature needs to be kept in sync manually. To eliminate this manual checking, introduce a new macro that verifies at compile time that the two function declarations use the same signature. The idea is to run the C declaration through bindgen, and then have rustc verify that the function pointers have the same type. The main commit of this series is "rust: add #[export] macro". Please see its commit message for more details. Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> --- Changes in v2: - Various improvements to documentation. - Split out quote! changes into its own commit. - Link to v1: https://lore.kernel.org/r/20250227-export-macro-v1-0-948775fc37aa@xxxxxxxxxx --- Alice Ryhl (5): rust: fix signature of rust_fmt_argument rust: macros: support additional tokens in quote! rust: add #[export] macro print: use new #[export] macro for rust_fmt_argument panic_qr: use new #[export] macro drivers/gpu/drm/drm_panic.c | 5 ----- drivers/gpu/drm/drm_panic_qr.rs | 15 +++++++++++---- include/drm/drm_panic.h | 7 +++++++ include/linux/sprintf.h | 3 +++ lib/vsprintf.c | 3 --- rust/bindings/bindings_helper.h | 4 ++++ rust/kernel/prelude.rs | 2 +- rust/kernel/print.rs | 10 +++++----- rust/macros/export.rs | 28 ++++++++++++++++++++++++++++ rust/macros/helpers.rs | 19 ++++++++++++++++++- rust/macros/lib.rs | 24 ++++++++++++++++++++++++ rust/macros/quote.rs | 21 +++++++++++++++++++-- 12 files changed, 120 insertions(+), 21 deletions(-) --- base-commit: a64dcfb451e254085a7daee5fe51bf22959d52d3 change-id: 20250227-export-macro-9aa9f1016d8c Best regards, -- Alice Ryhl <aliceryhl@xxxxxxxxxx>
