From fc6e66f4696b63b8a2645a2bcea407cb04bd0666 Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Tue, 28 May 2024 14:58:05 +0000 Subject: rust: add abstraction for `struct page` Adds a new struct called `Page` that wraps a pointer to `struct page`. This struct is assumed to hold ownership over the page, so that Rust code can allocate and manage pages directly. The page type has various methods for reading and writing into the page. These methods will temporarily map the page to allow the operation. All of these methods use a helper that takes an offset and length, performs bounds checks, and returns a pointer to the given offset in the page. This patch only adds support for pages of order zero, as that is all Rust Binder needs. However, it is written to make it easy to add support for higher-order pages in the future. To do that, you would add a const generic parameter to `Page` that specifies the order. Most of the methods do not need to be adjusted, as the logic for dealing with mapping multiple pages at once can be isolated to just the `with_pointer_into_page` method. Rust Binder needs to manage pages directly as that is how transactions are delivered: Each process has an mmap'd region for incoming transactions. When an incoming transaction arrives, the Binder driver will choose a region in the mmap, allocate and map the relevant pages manually, and copy the incoming transaction directly into the page. This architecture allows the driver to copy transactions directly from the address space of one process to another, without an intermediate copy to a kernel buffer. This code is based on Wedson's page abstractions from the old rust branch, but it has been modified by Alice by removing the incomplete support for higher-order pages, by introducing the `with_*` helpers to consolidate the bounds checking logic into a single place, and various other changes. Co-developed-by: Wedson Almeida Filho Signed-off-by: Wedson Almeida Filho Reviewed-by: Andreas Hindborg Reviewed-by: Trevor Gross Reviewed-by: Benno Lossin Reviewed-by: Boqun Feng Signed-off-by: Alice Ryhl Link: https://lore.kernel.org/r/20240528-alice-mm-v7-4-78222c31b8f4@google.com [ Fixed typos and added a few intra-doc links. - Miguel ] Signed-off-by: Miguel Ojeda --- rust/kernel/lib.rs | 1 + 1 file changed, 1 insertion(+) (limited to 'rust/kernel/lib.rs') diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 767026db068e..5d310e79485f 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -35,6 +35,7 @@ pub mod ioctl; pub mod kunit; #[cfg(CONFIG_NET)] pub mod net; +pub mod page; pub mod prelude; pub mod print; mod static_assert; -- cgit v1.2.3