On 02.08.24 09:38, Alice Ryhl wrote: > This is a follow-up to the page abstractions [1] that were recently > merged in 6.11. Rust Binder will need these abstractions to manipulate > the vma in its implementation of the mmap fop on the Binder file. > > This patch is based on Wedson's implementation on the old rust branch, > but has been changed significantly. All mistakes are Alice's. > > Link: https://lore.kernel.org/r/20240528-alice-mm-v7-4-78222c31b8f4@xxxxxxxxxx [1] > Co-developed-by: Wedson Almeida Filho <wedsonaf@xxxxxxxxx> > Signed-off-by: Wedson Almeida Filho <wedsonaf@xxxxxxxxx> > Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> I have one nit below, with that fixed: Reviewed-by: Benno Lossin <benno.lossin@xxxxxxxxx> > diff --git a/rust/kernel/mm/virt.rs b/rust/kernel/mm/virt.rs > new file mode 100644 > index 000000000000..ec8cadb09626 > --- /dev/null > +++ b/rust/kernel/mm/virt.rs > @@ -0,0 +1,204 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +// Copyright (C) 2024 Google LLC. > + > +//! Virtual memory. > + > +use crate::{ > + bindings, > + error::{to_result, Result}, > + page::Page, > + types::Opaque, > +}; > + > +/// A wrapper for the kernel's `struct vm_area_struct`. > +/// > +/// It represents an area of virtual memory. > +/// > +/// # Invariants > +/// > +/// * If the caller has shared access to this type, then they must hold the mmap read lock. > +/// * If the caller has exclusive access to this type, then they must hold the mmap write lock. > +#[repr(transparent)] > +pub struct VmArea { > + vma: Opaque<bindings::vm_area_struct>, > +} > + > +impl VmArea { > + /// Access a virtual memory area given a raw pointer. > + /// > + /// # Safety > + /// > + /// Callers must ensure that `vma` is valid for the duration of 'a, and that the mmap read lock > + /// (or write lock) is held for at least the duration of 'a. > + #[inline] > + pub unsafe fn from_raw_vma<'a>(vma: *const bindings::vm_area_struct) -> &'a Self { I think this also should be named `from_raw`. I took a look at your conversation with Christian Brauner and I personally don't see the benefit of `File::from_raw_file` over `File::from_raw`. To me it's clear that this function takes some raw C structure that represents a `File` and turns it into a `File`. In the situation where there are multiple ways of creating something from different C structs, I think we should include the name. But if there is only one possible struct, then the name should be `from_raw`. Do you think we should re-open that discussion/start a new one on a naming convention for this? --- Cheers, Benno > + // SAFETY: The caller ensures that the invariants are satisfied for the duration of 'a. > + unsafe { &*vma.cast() } > + }
