| Message ID | 20250228-export-macro-v2-0-569cc7e8926c@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Check Rust signatures at compile time | expand |
On Fri, Feb 28, 2025 at 12:39:29PM +0000, Alice Ryhl wrote: > 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. Thanks for the cover letter, makes much more sense now!
On Fri, Feb 28, 2025 at 1:40 PM Alice Ryhl <aliceryhl@google.com> wrote: > > This is because cbindgen assumes a > cargo-based buildsystem, so it is not compatible with the kernel's build > system. I don't think this is true (checking is already a very good justification, so we don't need this to justify the series): https://lore.kernel.org/rust-for-linux/CANiq72mHVbnmA_G1Fx3rz06RXA+=K5ERoWKjH-UDJ9cKxvKQ1g@mail.gmail.com/ Cheers, Miguel
On Fri, Feb 28, 2025 at 2:12 PM Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> wrote: > > On Fri, Feb 28, 2025 at 1:40 PM Alice Ryhl <aliceryhl@google.com> wrote: > > > > This is because cbindgen assumes a > > cargo-based buildsystem, so it is not compatible with the kernel's build > > system. > > I don't think this is true (checking is already a very good > justification, so we don't need this to justify the series): > > https://lore.kernel.org/rust-for-linux/CANiq72mHVbnmA_G1Fx3rz06RXA+=K5ERoWKjH-UDJ9cKxvKQ1g@mail.gmail.com/ Huh, I thought for sure it did. Alice
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@google.com> --- 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@google.com --- 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,