Messages in this thread | | | Date | Sat, 24 Jun 2023 14:55:03 +0000 | From | Björn Roy Baron <> | Subject | Re: [PATCH 2/7] rust: add derive macro for `Zeroable` |
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On Saturday, June 24th, 2023 at 11:25, Benno Lossin <benno.lossin@proton.me> wrote:
> Add a derive proc-macro for the `Zeroable` trait. The macro supports > structs where every field implements the `Zeroable` trait. This way > `unsafe` implementations can be avoided. > > The macro is split into two parts: > - a proc-macro to parse generics into impl and ty generics, > - a declarative macro that expands to the impl block. > > Suggested-by: Asahi Lina <lina@asahilina.net> > Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
> --- > rust/kernel/init/macros.rs | 28 ++++++++++++++++++++++++++++ > rust/kernel/prelude.rs | 2 +- > rust/macros/lib.rs | 20 ++++++++++++++++++++ > rust/macros/quote.rs | 6 ++++++ > rust/macros/zeroable.rs | 25 +++++++++++++++++++++++++ > 5 files changed, 80 insertions(+), 1 deletion(-) > create mode 100644 rust/macros/zeroable.rs > > diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs > index fbaebd34f218..e8165ff53a94 100644 > --- a/rust/kernel/init/macros.rs > +++ b/rust/kernel/init/macros.rs > @@ -1213,3 +1213,31 @@ macro_rules! __init_internal { > ); > }; > } > + > +#[doc(hidden)] > +#[macro_export] > +macro_rules! __derive_zeroable { > + (parse_input: > + @sig( > + $(#[$($struct_attr:tt)*])* > + $vis:vis struct $name:ident > + $(where $($whr:tt)*)? > + ), > + @impl_generics($($impl_generics:tt)*), > + @ty_generics($($ty_generics:tt)*), > + @body({ > + $( > + $(#[$($field_attr:tt)*])* > + $field:ident : $field_ty:ty > + ),* $(,)? > + }), > + ) => { > + // SAFETY: every field type implements `Zeroable` and padding bytes may be zero. > + #[automatically_derived] > + unsafe impl<$($impl_generics)*> $crate::Zeroable for $name<$($ty_generics)*> > + where > + $($field_ty: $crate::Zeroable,)* > + $($($whr)*)? > + {} > + }; > +} > diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs > index c28587d68ebc..ae21600970b3 100644 > --- a/rust/kernel/prelude.rs > +++ b/rust/kernel/prelude.rs > @@ -18,7 +18,7 @@ > pub use alloc::{boxed::Box, vec::Vec}; > > #[doc(no_inline)] > -pub use macros::{module, pin_data, pinned_drop, vtable}; > +pub use macros::{module, pin_data, pinned_drop, vtable, Zeroable}; > > pub use super::build_assert; > > diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs > index 3fc74cb4ea19..9f056a5c780a 100644 > --- a/rust/macros/lib.rs > +++ b/rust/macros/lib.rs > @@ -10,6 +10,7 @@ > mod pin_data; > mod pinned_drop; > mod vtable; > +mod zeroable; > > use proc_macro::TokenStream; > > @@ -246,3 +247,22 @@ pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream { > pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream { > pinned_drop::pinned_drop(args, input) > } > + > +/// Derives the [`Zeroable`] trait for the given struct. > +/// > +/// This can only be used for structs where every field implements the [`Zeroable`] trait. > +/// > +/// # Examples > +/// > +/// ```rust > +/// #[derive(Zeroable)] > +/// pub struct DriverData { > +/// id: i64, > +/// buf_ptr: *mut u8, > +/// len: usize, > +/// } > +/// ``` > +#[proc_macro_derive(Zeroable)] > +pub fn derive_zeroable(input: TokenStream) -> TokenStream { > + zeroable::derive(input) > +} > diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs > index dddbb4e6f4cb..b76c198a4ed5 100644 > --- a/rust/macros/quote.rs > +++ b/rust/macros/quote.rs > @@ -124,6 +124,12 @@ macro_rules! quote_spanned { > )); > quote_spanned!(@proc $v $span $($tt)*); > }; > + (@proc $v:ident $span:ident ; $($tt:tt)*) => { > + $v.push(::proc_macro::TokenTree::Punct( > + ::proc_macro::Punct::new(';', ::proc_macro::Spacing::Alone) > + )); > + quote_spanned!(@proc $v $span $($tt)*); > + }; > (@proc $v:ident $span:ident $id:ident $($tt:tt)*) => { > $v.push(::proc_macro::TokenTree::Ident(::proc_macro::Ident::new(stringify!($id), $span))); > quote_spanned!(@proc $v $span $($tt)*); > diff --git a/rust/macros/zeroable.rs b/rust/macros/zeroable.rs > new file mode 100644 > index 000000000000..cddb866c44ef > --- /dev/null > +++ b/rust/macros/zeroable.rs > @@ -0,0 +1,25 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +use crate::helpers::{parse_generics, Generics}; > +use proc_macro::TokenStream; > + > +pub(crate) fn derive(input: TokenStream) -> TokenStream { > + let ( > + Generics { > + impl_generics, > + ty_generics, > + }, > + mut rest, > + ) = parse_generics(input); > + // This should be the body of the struct `{...}`. > + let last = rest.pop(); > + quote! { > + ::kernel::__derive_zeroable!( > + parse_input: > + @sig(#(#rest)*), > + @impl_generics(#(#impl_generics)*), > + @ty_generics(#(#ty_generics)*), > + @body(#last), > + ); > + } > +} > -- > 2.41.0
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