Commit graph

10 commits

Author SHA1 Message Date
Tamir Duberstein
dc35ddcf97 rust: enable clippy::ref_as_ptr lint
In Rust 1.78.0, Clippy introduced the `ref_as_ptr` lint [1]:

> Using `as` casts may result in silently changing mutability or type.

While this doesn't eliminate unchecked `as` conversions, it makes such
conversions easier to scrutinize.  It also has the slight benefit of
removing a degree of freedom on which to bikeshed. Thus apply the
changes and enable the lint -- no functional change intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#ref_as_ptr [1]
Suggested-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/all/D8PGG7NTWB6U.3SS3A5LN4XWMN@proton.me/
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-6-f43b024581e8@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-06-22 23:09:32 +02:00
Tamir Duberstein
fcad9bbf9e rust: enable clippy::ptr_as_ptr lint
In Rust 1.51.0, Clippy introduced the `ptr_as_ptr` lint [1]:

> Though `as` casts between raw pointers are not terrible,
> `pointer::cast` is safer because it cannot accidentally change the
> pointer's mutability, nor cast the pointer to other types like `usize`.

There are a few classes of changes required:
- Modules generated by bindgen are marked
  `#[allow(clippy::ptr_as_ptr)]`.
- Inferred casts (` as _`) are replaced with `.cast()`.
- Ascribed casts (` as *... T`) are replaced with `.cast::<T>()`.
- Multistep casts from references (` as *const _ as *const T`) are
  replaced with `core::ptr::from_ref(&x).cast()` with or without `::<T>`
  according to the previous rules. The `core::ptr::from_ref` call is
  required because `(x as *const _).cast::<T>()` results in inference
  failure.
- Native literal C strings are replaced with `c_str!().as_char_ptr()`.
- `*mut *mut T as _` is replaced with `let *mut *const T = (*mut *mut
  T)`.cast();` since pointer to pointer can be confusing.

Apply these changes and enable the lint -- no functional change
intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#ptr_as_ptr [1]
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250615-ptr-as-ptr-v12-1-f43b024581e8@gmail.com
[ Added `.cast()` for `opp`. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-06-22 23:08:42 +02:00
Pekka Ristola
946026ba42
rust: file: improve safety comments
Some of the safety comments in `LocalFile`'s methods incorrectly refer to
the `File` type instead of `LocalFile`, so fix them to use the correct
type.

Also add missing Markdown code spans around lifetimes in the safety
comments, i.e. change 'a to `'a`.

Link: https://github.com/Rust-for-Linux/linux/issues/1165
Signed-off-by: Pekka Ristola <pekkarr@protonmail.com>
Link: https://lore.kernel.org/20250527204636.12573-2-pekkarr@protonmail.com
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-05-30 07:12:05 +02:00
Pekka Ristola
15ecd83dc0
rust: file: mark LocalFile as repr(transparent)
Unsafe code in `LocalFile`'s methods assumes that the type has the same
layout as the inner `bindings::file`. This is not guaranteed by the default
struct representation in Rust, but requires specifying the `transparent`
representation.

The `File` struct (which also wraps `bindings::file`) is already marked as
`repr(transparent)`, so this change makes their layouts equivalent.

Fixes: 851849824b ("rust: file: add Rust abstraction for `struct file`")
Closes: https://github.com/Rust-for-Linux/linux/issues/1165
Signed-off-by: Pekka Ristola <pekkarr@protonmail.com>
Link: https://lore.kernel.org/20250527204636.12573-1-pekkarr@protonmail.com
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-05-30 07:12:05 +02:00
Linus Torvalds
4e82c87058 Rust changes for v6.15
Toolchain and infrastructure:
 
  - Extract the 'pin-init' API from the 'kernel' crate and make it into
    a standalone crate.
 
    In order to do this, the contents are rearranged so that they can
    easily be kept in sync with the version maintained out-of-tree that
    other projects have started to use too (or plan to, like QEMU).
 
    This will reduce the maintenance burden for Benno, who will now have
    his own sub-tree, and will simplify future expected changes like the
    move to use 'syn' to simplify the implementation.
 
  - Add '#[test]'-like support based on KUnit.
 
    We already had doctests support based on KUnit, which takes the
    examples in our Rust documentation and runs them under KUnit.
 
    Now, we are adding the beginning of the support for "normal" tests,
    similar to those the '#[test]' tests in userspace Rust. For instance:
 
        #[kunit_tests(my_suite)]
        mod tests {
            #[test]
            fn my_test() {
                assert_eq!(1 + 1, 2);
            }
        }
 
    Unlike with doctests, the 'assert*!'s do not map to the KUnit
    assertion APIs yet.
 
  - Check Rust signatures at compile time for functions called from C by
    name.
 
    In particular, introduce a new '#[export]' macro that can be placed
    in the Rust function definition. It will ensure that the function
    declaration on the C side matches the signature on the Rust function:
 
        #[export]
        pub unsafe extern "C" fn my_function(a: u8, b: i32) -> usize {
            // ...
        }
 
    The macro essentially forces the compiler to compare the types of
    the actual Rust function and the 'bindgen'-processed C signature.
 
    These cases are rare so far. In the future, we may consider
    introducing another tool, 'cbindgen', to generate C headers
    automatically. Even then, having these functions explicitly marked
    may be a good idea anyway.
 
  - Enable the 'raw_ref_op' Rust feature: it is already stable, and
    allows us to use the new '&raw' syntax, avoiding a couple macros.
    After everyone has migrated, we will disallow the macros.
 
  - Pass the correct target to 'bindgen' on Usermode Linux.
 
  - Fix 'rusttest' build in macOS.
 
 'kernel' crate:
 
  - New 'hrtimer' module: add support for setting up intrusive timers
    without allocating when starting the timer. Add support for
    'Pin<Box<_>>', 'Arc<_>', 'Pin<&_>' and 'Pin<&mut _>' as pointer types
    for use with timer callbacks. Add support for setting clock source
    and timer mode.
 
  - New 'dma' module: add a simple DMA coherent allocator abstraction and
    a test sample driver.
 
  - 'list' module: make the linked list 'Cursor' point between elements,
    rather than at an element, which is more convenient to us and allows
    for cursors to empty lists; and document it with examples of how to
    perform common operations with the provided methods.
 
  - 'str' module: implement a few traits for 'BStr' as well as the
    'strip_prefix()' method.
 
  - 'sync' module: add 'Arc::as_ptr'.
 
  - 'alloc' module: add 'Box::into_pin'.
 
  - 'error' module: extend the 'Result' documentation, including a few
    examples on different ways of handling errors, a warning about using
    methods that may panic, and links to external documentation.
 
 'macros' crate:
 
   - 'module' macro: add the 'authors' key to support multiple authors.
     The original key will be kept until everyone has migrated.
 
 Documentation:
 
  - Add error handling sections.
 
 MAINTAINERS:
 
  - Add Danilo Krummrich as reviewer of the Rust "subsystem".
 
  - Add 'RUST [PIN-INIT]' entry with Benno Lossin as maintainer. It has
    its own sub-tree.
 
  - Add sub-tree for 'RUST [ALLOC]'.
 
  - Add 'DMA MAPPING HELPERS DEVICE DRIVER API [RUST]' entry with Abdiel
    Janulgue as primary maintainer. It will go through the sub-tree of
    the 'RUST [ALLOC]' entry.
 
  - Add 'HIGH-RESOLUTION TIMERS [RUST]' entry with Andreas Hindborg as
    maintainer. It has its own sub-tree.
 
 And a few other cleanups and improvements.
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Merge tag 'rust-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

Pull Rust updates from Miguel Ojeda:
 "Toolchain and infrastructure:

   - Extract the 'pin-init' API from the 'kernel' crate and make it into
     a standalone crate.

     In order to do this, the contents are rearranged so that they can
     easily be kept in sync with the version maintained out-of-tree that
     other projects have started to use too (or plan to, like QEMU).

     This will reduce the maintenance burden for Benno, who will now
     have his own sub-tree, and will simplify future expected changes
     like the move to use 'syn' to simplify the implementation.

   - Add '#[test]'-like support based on KUnit.

     We already had doctests support based on KUnit, which takes the
     examples in our Rust documentation and runs them under KUnit.

     Now, we are adding the beginning of the support for "normal" tests,
     similar to those the '#[test]' tests in userspace Rust. For
     instance:

         #[kunit_tests(my_suite)]
         mod tests {
             #[test]
             fn my_test() {
                 assert_eq!(1 + 1, 2);
             }
         }

     Unlike with doctests, the 'assert*!'s do not map to the KUnit
     assertion APIs yet.

   - Check Rust signatures at compile time for functions called from C
     by name.

     In particular, introduce a new '#[export]' macro that can be placed
     in the Rust function definition. It will ensure that the function
     declaration on the C side matches the signature on the Rust
     function:

         #[export]
         pub unsafe extern "C" fn my_function(a: u8, b: i32) -> usize {
             // ...
         }

     The macro essentially forces the compiler to compare the types of
     the actual Rust function and the 'bindgen'-processed C signature.

     These cases are rare so far. In the future, we may consider
     introducing another tool, 'cbindgen', to generate C headers
     automatically. Even then, having these functions explicitly marked
     may be a good idea anyway.

   - Enable the 'raw_ref_op' Rust feature: it is already stable, and
     allows us to use the new '&raw' syntax, avoiding a couple macros.
     After everyone has migrated, we will disallow the macros.

   - Pass the correct target to 'bindgen' on Usermode Linux.

   - Fix 'rusttest' build in macOS.

  'kernel' crate:

   - New 'hrtimer' module: add support for setting up intrusive timers
     without allocating when starting the timer. Add support for
     'Pin<Box<_>>', 'Arc<_>', 'Pin<&_>' and 'Pin<&mut _>' as pointer
     types for use with timer callbacks. Add support for setting clock
     source and timer mode.

   - New 'dma' module: add a simple DMA coherent allocator abstraction
     and a test sample driver.

   - 'list' module: make the linked list 'Cursor' point between
     elements, rather than at an element, which is more convenient to us
     and allows for cursors to empty lists; and document it with
     examples of how to perform common operations with the provided
     methods.

   - 'str' module: implement a few traits for 'BStr' as well as the
     'strip_prefix()' method.

   - 'sync' module: add 'Arc::as_ptr'.

   - 'alloc' module: add 'Box::into_pin'.

   - 'error' module: extend the 'Result' documentation, including a few
     examples on different ways of handling errors, a warning about
     using methods that may panic, and links to external documentation.

  'macros' crate:

   - 'module' macro: add the 'authors' key to support multiple authors.
     The original key will be kept until everyone has migrated.

  Documentation:

   - Add error handling sections.

  MAINTAINERS:

   - Add Danilo Krummrich as reviewer of the Rust "subsystem".

   - Add 'RUST [PIN-INIT]' entry with Benno Lossin as maintainer. It has
     its own sub-tree.

   - Add sub-tree for 'RUST [ALLOC]'.

   - Add 'DMA MAPPING HELPERS DEVICE DRIVER API [RUST]' entry with
     Abdiel Janulgue as primary maintainer. It will go through the
     sub-tree of the 'RUST [ALLOC]' entry.

   - Add 'HIGH-RESOLUTION TIMERS [RUST]' entry with Andreas Hindborg as
     maintainer. It has its own sub-tree.

  And a few other cleanups and improvements"

* tag 'rust-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (71 commits)
  rust: dma: add `Send` implementation for `CoherentAllocation`
  rust: macros: fix `make rusttest` build on macOS
  rust: block: refactor to use `&raw mut`
  rust: enable `raw_ref_op` feature
  rust: uaccess: name the correct function
  rust: rbtree: fix comments referring to Box instead of KBox
  rust: hrtimer: add maintainer entry
  rust: hrtimer: add clocksource selection through `ClockId`
  rust: hrtimer: add `HrTimerMode`
  rust: hrtimer: implement `HrTimerPointer` for `Pin<Box<T>>`
  rust: alloc: add `Box::into_pin`
  rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&mut T>`
  rust: hrtimer: implement `UnsafeHrTimerPointer` for `Pin<&T>`
  rust: hrtimer: add `hrtimer::ScopedHrTimerPointer`
  rust: hrtimer: add `UnsafeHrTimerPointer`
  rust: hrtimer: allow timer restart from timer handler
  rust: str: implement `strip_prefix` for `BStr`
  rust: str: implement `AsRef<BStr>` for `[u8]` and `BStr`
  rust: str: implement `Index` for `BStr`
  rust: str: implement `PartialEq` for `BStr`
  ...
2025-03-30 17:03:26 -07:00
Kunwu Chan
e27b0e3c54
rust: file: optimize rust symbol generation for FileDescriptorReservation
When build the kernel using the llvm-18.1.3-rust-1.85.0-x86_64
with ARCH=arm64, the following symbols are generated:

$ nm vmlinux | grep ' _R'.*FileDescriptorReservation | rustfilt
... T <kernel::fs::file::FileDescriptorReservation>::fd_install
... T <kernel::fs::file::FileDescriptorReservation>::get_unused_fd_flags
... T <kernel::fs::file::FileDescriptorReservation as core::ops::drop::Drop>::drop

These Rust symbols are trivial wrappers around the C functions
fd_install, put_unused_fd and put_task_struct. It
doesn't make sense to go through a trivial wrapper for these
functions, so mark them inline.

Link: https://github.com/Rust-for-Linux/linux/issues/1145
Suggested-by: Alice Ryhl <aliceryhl@google.com>
Co-developed-by: Grace Deng <Grace.Deng006@Gmail.com>
Signed-off-by: Grace Deng <Grace.Deng006@Gmail.com>
Signed-off-by: Kunwu Chan <kunwu.chan@hotmail.com>
Link: https://lore.kernel.org/r/20250317023702.2360726-1-kunwu.chan@linux.dev
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-03-18 09:25:52 +01:00
Borys Tyran
cd1ed11a67 rust: improve lifetimes markup
Improve lifetimes markup; e.g. from:

    /// ... 'a ...

to:

    /// ... `'a` ...

This will make lifetimes display as code span with Markdown and make it
more consistent with rest of the docs.

Link: https://github.com/Rust-for-Linux/linux/issues/1138
Signed-off-by: Borys Tyran <borys.tyran@protonmail.com>
Link: https://lore.kernel.org/r/20250207142437.112435-1-borys.tyran@protonmail.com
[ Reworded and changed Closes tag to Link. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-08 23:04:38 +01:00
Wedson Almeida Filho
5da9857b12
rust: file: add FileDescriptorReservation
Allow for the creation of a file descriptor in two steps: first, we
reserve a slot for it, then we commit or drop the reservation. The first
step may fail (e.g., the current process ran out of available slots),
but commit and drop never fail (and are mutually exclusive).

This is needed by Rust Binder when fds are sent from one process to
another. It has to be a two-step process to properly handle the case
where multiple fds are sent: The operation must fail or succeed
atomically, which we achieve by first reserving the fds we need, and
only installing the files once we have reserved enough fds to send the
files.

Fd reservations assume that the value of `current` does not change
between the call to get_unused_fd_flags and the call to fd_install (or
put_unused_fd). By not implementing the Send trait, this abstraction
ensures that the `FileDescriptorReservation` cannot be moved into a
different process.

Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-6-88484f7a3dcf@google.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-09-30 13:02:29 +02:00
Wedson Almeida Filho
a3df991d3d
rust: cred: add Rust abstraction for struct cred
Add a wrapper around `struct cred` called `Credential`, and provide
functionality to get the `Credential` associated with a `File`.

Rust Binder must check the credentials of processes when they attempt to
perform various operations, and these checks usually take a
`&Credential` as parameter. The security_binder_set_context_mgr function
would be one example. This patch is necessary to access these security_*
methods from Rust.

This Rust abstraction makes the following assumptions about the C side:
* `struct cred` is refcounted with `get_cred`/`put_cred`.
* It's okay to transfer a `struct cred` across threads, that is, you do
  not need to call `put_cred` on the same thread as where you called
  `get_cred`.
* The `euid` field of a `struct cred` never changes after
  initialization.
* The `f_cred` field of a `struct file` never changes after
  initialization.

Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-4-88484f7a3dcf@google.com
Reviewed-by: Kees Cook <kees@kernel.org>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-09-30 13:02:28 +02:00
Wedson Almeida Filho
851849824b
rust: file: add Rust abstraction for struct file
This abstraction makes it possible to manipulate the open files for a
process. The new `File` struct wraps the C `struct file`. When accessing
it using the smart pointer `ARef<File>`, the pointer will own a
reference count to the file. When accessing it as `&File`, then the
reference does not own a refcount, but the borrow checker will ensure
that the reference count does not hit zero while the `&File` is live.

Since this is intended to manipulate the open files of a process, we
introduce an `fget` constructor that corresponds to the C `fget`
method. In future patches, it will become possible to create a new fd in
a process and bind it to a `File`. Rust Binder will use these to send
fds from one process to another.

We also provide a method for accessing the file's flags. Rust Binder
will use this to access the flags of the Binder fd to check whether the
non-blocking flag is set, which affects what the Binder ioctl does.

This introduces a struct for the EBADF error type, rather than just
using the Error type directly. This has two advantages:
* `File::fget` returns a `Result<ARef<File>, BadFdError>`, which the
  compiler will represent as a single pointer, with null being an error.
  This is possible because the compiler understands that `BadFdError`
  has only one possible value, and it also understands that the
  `ARef<File>` smart pointer is guaranteed non-null.
* Additionally, we promise to users of the method that the method can
  only fail with EBADF, which means that they can rely on this promise
  without having to inspect its implementation.
That said, there are also two disadvantages:
* Defining additional error types involves boilerplate.
* The question mark operator will only utilize the `From` trait once,
  which prevents you from using the question mark operator on
  `BadFdError` in methods that return some third error type that the
  kernel `Error` is convertible into. (However, it works fine in methods
  that return `Error`.)

Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20240915-alice-file-v10-3-88484f7a3dcf@google.com
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-09-30 13:02:28 +02:00