linux.git/rust/kernel/lib.rs, branch v6.9-rc2

rust: add `container_of!` macro

2024-02-25T18:17:31+00:00

This macro is used to obtain a pointer to an entire struct
when given a pointer to a field in that struct.

Signed-off-by: Wedson Almeida Filho 
Reviewed-by: Alice Ryhl 
Tested-by: Alice Ryhl 
Signed-off-by: Matt Gilbride 
Link: https://lore.kernel.org/r/20240219-b4-rbtree-v2-1-0b113aab330d@google.com
Signed-off-by: Miguel Ojeda

rust: kernel: stop using ptr_metadata feature

2024-02-18T20:22:27+00:00

The `byte_sub` method was stabilized in Rust 1.75.0. By using that
method, we no longer need the unstable `ptr_metadata` feature for
implementing `Arc::from_raw`.

This brings us one step closer towards not using unstable compiler
features.

Reviewed-by: Benno Lossin 
Reviewed-by: Martin Rodriguez Reboredo 
Reviewed-by: Trevor Gross 
Signed-off-by: Alice Ryhl 
Link: https://lore.kernel.org/r/20240215104601.1267763-1-aliceryhl@google.com
[ Reworded title. ]
Signed-off-by: Miguel Ojeda

rust: kernel: add srctree-relative doclinks

2024-02-18T20:22:27+00:00

Convert existing references to C header files to make use of
Commit bc2e7d5c298a ("rust: support `srctree`-relative links").

Signed-off-by: Valentin Obst 
Reviewed-by: Trevor Gross 
Reviewed-by: Martin Rodriguez Reboredo 
Reviewed-by: Alice Ryhl 
Link: https://lore.kernel.org/r/20240131-doc-fixes-v3-v3-4-0c8af94ed7de@valentinobst.de
Signed-off-by: Miguel Ojeda

rust: time: add msecs to jiffies conversion

2024-01-28T18:50:48+00:00

Defines type aliases and conversions for msecs and jiffies.

This is used by Rust Binder for process freezing. There, we want to
sleep until the freeze operation completes, but we want to be able to
abort the process freezing if it doesn't complete within some timeout.
The freeze timeout is supplied in msecs.

Note that we need to convert to jiffies in Binder. It is not enough to
introduce a variant of `CondVar::wait_timeout` that takes the timeout in
msecs because we need to be able to restart the sleep with the remaining
sleep duration if it is interrupted, and if the API takes msecs rather
than jiffies, then that would require a conversion roundtrip jiffies->
msecs->jiffies that is best avoided.

Suggested-by: Boqun Feng 
Reviewed-by: Boqun Feng 
Reviewed-by: Benno Lossin 
Reviewed-by: Martin Rodriguez Reboredo 
Reviewed-by: Tiago Lam 
Signed-off-by: Alice Ryhl 
Link: https://lore.kernel.org/r/20240108-rb-new-condvar-methods-v4-2-88e0c871cc05@google.com
Signed-off-by: Miguel Ojeda

rust: upgrade to Rust 1.75.0

2024-01-22T14:18:05+00:00

This is the next upgrade to the Rust toolchain, from 1.74.1 to 1.75.0
(i.e. the latest) [1].

See the upgrade policy [2] and the comments on the first upgrade in
commit 3ed03f4da06e ("rust: upgrade to Rust 1.68.2").

# Unstable features

The `const_maybe_uninit_zeroed` unstable feature [3] was stabilized in
Rust 1.75.0, which we were using in the PHYLIB abstractions.

The only unstable features allowed to be used outside the `kernel` crate
are still `new_uninit,offset_of`, though other code to be upstreamed
may increase the list.

Please see [4] for details.

# Other improvements

Rust 1.75.0 stabilized `pointer_byte_offsets` [5] which we could
potentially use as an alternative for `ptr_metadata` in the future.

# Required changes

For this upgrade, no changes were required (i.e. on our side).

# `alloc` upgrade and reviewing

The vast majority of changes are due to our `alloc` fork being upgraded
at once.

There are two kinds of changes to be aware of: the ones coming from
upstream, which we should follow as closely as possible, and the updates
needed in our added fallible APIs to keep them matching the newer
infallible APIs coming from upstream.

Instead of taking a look at the diff of this patch, an alternative
approach is reviewing a diff of the changes between upstream `alloc` and
the kernel's. This allows to easily inspect the kernel additions only,
especially to check if the fallible methods we already have still match
the infallible ones in the new version coming from upstream.

Another approach is reviewing the changes introduced in the additions in
the kernel fork between the two versions. This is useful to spot
potentially unintended changes to our additions.

To apply these approaches, one may follow steps similar to the following
to generate a pair of patches that show the differences between upstream
Rust and the kernel (for the subset of `alloc` we use) before and after
applying this patch:

# Get the difference with respect to the old version.
git -C rust checkout $(linux/scripts/min-tool-version.sh rustc)
git -C linux ls-tree -r --name-only HEAD -- rust/alloc |
cut -d/ -f3- |
grep -Fv README.md |
xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH
git -C linux diff --patch-with-stat --summary -R > old.patch
git -C linux restore rust/alloc

# Apply this patch.
git -C linux am rust-upgrade.patch

# Get the difference with respect to the new version.
git -C rust checkout $(linux/scripts/min-tool-version.sh rustc)
git -C linux ls-tree -r --name-only HEAD -- rust/alloc |
cut -d/ -f3- |
grep -Fv README.md |
xargs -IPATH cp rust/library/alloc/src/PATH linux/rust/alloc/PATH
git -C linux diff --patch-with-stat --summary -R > new.patch
git -C linux restore rust/alloc

Now one may check the `new.patch` to take a look at the additions (first
approach) or at the difference between those two patches (second
approach). For the latter, a side-by-side tool is recommended.

Link: https://github.com/rust-lang/rust/blob/stable/RELEASES.md#version-1750-2023-12-28 [1]
Link: https://rust-for-linux.com/rust-version-policy [2]
Link: https://github.com/rust-lang/rust/issues/91850 [3]
Link: https://github.com/Rust-for-Linux/linux/issues/2 [4]
Link: https://github.com/rust-lang/rust/issues/96283 [5]
Reviewed-by: Vincenzo Palazzo
Reviewed-by: Martin Rodriguez Reboredo
Tested-by: Boqun Feng
Link: https://lore.kernel.org/r/20231224172128.271447-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda

rust: core abstractions for network PHY drivers

2023-12-15T09:35:50+00:00

This patch adds abstractions to implement network PHY drivers; the
driver registration and bindings for some of callback functions in
struct phy_driver and many genphy_ functions.

This feature is enabled with CONFIG_RUST_PHYLIB_ABSTRACTIONS=y.

This patch enables unstable const_maybe_uninit_zeroed feature for
kernel crate to enable unsafe code to handle a constant value with
uninitialized data. With the feature, the abstractions can initialize
a phy_driver structure with zero easily; instead of initializing all
the members by hand. It's supposed to be stable in the not so distant
future.

Link: https://github.com/rust-lang/rust/pull/116218

Signed-off-by: FUJITA Tomonori 
Reviewed-by: Andrew Lunn 
Reviewed-by: Alice Ryhl 
Signed-off-by: David S. Miller

rust: workqueue: add helper for defining work_struct fields

2023-09-25T19:46:42+00:00

The main challenge with defining `work_struct` fields is making sure
that the function pointer stored in the `work_struct` is appropriate for
the work item type it is embedded in. It needs to know the offset of the
`work_struct` field being used (even if there are several!) so that it
can do a `container_of`, and it needs to know the type of the work item
so that it can call into the right user-provided code. All of this needs
to happen in a way that provides a safe API to the user, so that users
of the workqueue cannot mix up the function pointers.

There are three important pieces that are relevant when doing this:

 * The pointer type.
 * The work item struct. This is what the pointer points at.
 * The `work_struct` field. This is a field of the work item struct.

This patch introduces a separate trait for each piece. The pointer type
is given a `WorkItemPointer` trait, which pointer types need to
implement to be usable with the workqueue. This trait will be
implemented for `Arc` and `Box` in a later patch in this patchset.
Implementing this trait is unsafe because this is where the
`container_of` operation happens, but user-code will not need to
implement it themselves.

The work item struct should then implement the `WorkItem` trait. This
trait is where user-code specifies what they want to happen when a work
item is executed. It also specifies what the correct pointer type is.

Finally, to make the work item struct know the offset of its
`work_struct` field, we use a trait called `HasWork`. If a type
implements this trait, then the type declares that, at the given offset,
there is a field of type `Work`. The trait is marked unsafe
because the OFFSET constant must be correct, but we provide an
`impl_has_work!` macro that can safely implement `HasWork` on a type.
The macro expands to something that only compiles if the specified field
really has the type `Work`. It is used like this:

```
struct MyWorkItem {
    work_field: Work,
}

impl_has_work! {
    impl HasWork for MyWorkItem { self.work_field }
}
```

Note that since the `Work` type is annotated with an id, you can have
several `work_struct` fields by using a different id for each one.

Co-developed-by: Gary Guo 
Signed-off-by: Gary Guo 
Signed-off-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Martin Rodriguez Reboredo 
Reviewed-by: Andreas Hindborg 
Reviewed-by: Boqun Feng 
Signed-off-by: Tejun Heo

rust: workqueue: add low-level workqueue bindings

2023-09-25T19:46:42+00:00

Define basic low-level bindings to a kernel workqueue. The API defined
here can only be used unsafely. Later commits will provide safe
wrappers.

Co-developed-by: Gary Guo 
Signed-off-by: Gary Guo 
Signed-off-by: Alice Ryhl 
Reviewed-by: Martin Rodriguez Reboredo 
Reviewed-by: "Andreas Hindborg (Samsung)" 
Reviewed-by: Benno Lossin 
Reviewed-by: Boqun Feng 
Signed-off-by: Tejun Heo

rust: sync: add `Arc::{from_raw, into_raw}`

2023-09-25T19:46:41+00:00

These methods can be used to turn an `Arc` into a raw pointer and back,
in a way that preserves the metadata for fat pointers.

This is done using the unstable ptr_metadata feature [1]. However, it
could also be done using the unstable pointer_byte_offsets feature [2],
which is likely to have a shorter path to stabilization than
ptr_metadata.

Link: https://github.com/rust-lang/rust/issues/81513 [1]
Link: https://github.com/rust-lang/rust/issues/96283 [2]
Signed-off-by: Wedson Almeida Filho 
Co-developed-by: Alice Ryhl 
Signed-off-by: Alice Ryhl 
Reviewed-by: Gary Guo 
Reviewed-by: Martin Rodriguez Reboredo 
Reviewed-by: Benno Lossin 
Reviewed-by: Andreas Hindborg 
Reviewed-by: Boqun Feng 
Signed-off-by: Tejun Heo

Merge tag 'rust-6.6' of https://github.com/Rust-for-Linux/linux

2023-08-29T15:19:46+00:00

Pull rust updates from Miguel Ojeda:
 "In terms of lines, most changes this time are on the pinned-init API
  and infrastructure. While we have a Rust version upgrade, and thus a
  bunch of changes from the vendored 'alloc' crate as usual, this time
  those do not account for many lines.

  Toolchain and infrastructure:

   - Upgrade to Rust 1.71.1. This is the second such upgrade, which is a
     smaller jump compared to the last time.

     This version allows us to remove the '__rust_*' allocator functions
     -- the compiler now generates them as expected, thus now our
     'KernelAllocator' is used.

     It also introduces the 'offset_of!' macro in the standard library
     (as an unstable feature) which we will need soon. So far, we were
     using a declarative macro as a prerequisite in some not-yet-landed
     patch series, which did not support sub-fields (i.e. nested
     structs):

         #[repr(C)]
         struct S {
             a: u16,
             b: (u8, u8),
         }

         assert_eq!(offset_of!(S, b.1), 3);

   - Upgrade to bindgen 0.65.1. This is the first time we upgrade its
     version.

     Given it is a fairly big jump, it comes with a fair number of
     improvements/changes that affect us, such as a fix needed to
     support LLVM 16 as well as proper support for '__noreturn' C
     functions, which are now mapped to return the '!' type in Rust:

         void __noreturn f(void); // C
         pub fn f() -> !;         // Rust

   - 'scripts/rust_is_available.sh' improvements and fixes.

     This series takes care of all the issues known so far and adds a
     few new checks to cover for even more cases, plus adds some more
     help texts. All this together will hopefully make problematic
     setups easier to identify and to be solved by users building the
     kernel.

     In addition, it adds a test suite which covers all branches of the
     shell script, as well as tests for the issues found so far.

   - Support rust-analyzer for out-of-tree modules too.

   - Give 'cfg's to rust-analyzer for the 'core' and 'alloc' crates.

   - Drop 'scripts/is_rust_module.sh' since it is not needed anymore.

  Macros crate:

   - New 'paste!' proc macro.

     This macro is a more flexible version of 'concat_idents!': it
     allows the resulting identifier to be used to declare new items and
     it allows to transform the identifiers before concatenating them,
     e.g.

         let x_1 = 42;
         paste!(let [] = [];);
         assert!(x_1 == x_2);

     The macro is then used for several of the pinned-init API changes
     in this pull.

  Pinned-init API:

   - Make '#[pin_data]' compatible with conditional compilation of
     fields, allowing to write code like:

         #[pin_data]
         pub struct Foo {
             #[cfg(CONFIG_BAR)]
             a: Bar,
             #[cfg(not(CONFIG_BAR))]
             a: Baz,
         }

   - New '#[derive(Zeroable)]' proc macro for the 'Zeroable' trait,
     which allows 'unsafe' implementations for structs where every field
     implements the 'Zeroable' trait, e.g.:

         #[derive(Zeroable)]
         pub struct DriverData {
             id: i64,
             buf_ptr: *mut u8,
             len: usize,
         }

   - Add '..Zeroable::zeroed()' syntax to the 'pin_init!' macro for
     zeroing all other fields, e.g.:

         pin_init!(Buf {
             buf: [1; 64],
             ..Zeroable::zeroed()
         });

   - New '{,pin_}init_array_from_fn()' functions to create array
     initializers given a generator function, e.g.:

         let b: Box<[usize; 1_000]> = Box::init::(
             init_array_from_fn(|i| i)
         ).unwrap();

         assert_eq!(b.len(), 1_000);
         assert_eq!(b[123], 123);

   - New '{,pin_}chain' methods for '{,Pin}Init' that allow to
     execute a closure on the value directly after initialization, e.g.:

         let foo = init!(Foo {
             buf <- init::zeroed()
         }).chain(|foo| {
             foo.setup();
             Ok(())
         });

   - Support arbitrary paths in init macros, instead of just identifiers
     and generic types.

   - Implement the 'Zeroable' trait for the 'UnsafeCell' and
     'Opaque' types.

   - Make initializer values inaccessible after initialization.

   - Make guards in the init macros hygienic.

  'allocator' module:

   - Use 'krealloc_aligned()' in 'KernelAllocator::alloc' preventing
     misaligned allocations when the Rust 1.71.1 upgrade is applied
     later in this pull.

     The equivalent fix for the previous compiler version (where
     'KernelAllocator' is not yet used) was merged into 6.5 already,
     which added the 'krealloc_aligned()' function used here.

   - Implement 'KernelAllocator::{realloc, alloc_zeroed}' for
     performance, using 'krealloc_aligned()' too, which forwards the
     call to the C API.

  'types' module:

   - Make 'Opaque' be '!Unpin', removing the need to add a
     'PhantomPinned' field to Rust structs that contain C structs which
     must not be moved.

   - Make 'Opaque' use 'UnsafeCell' as the outer type, rather than
     inner.

  Documentation:

   - Suggest obtaining the source code of the Rust's 'core' library
     using the tarball instead of the repository.

  MAINTAINERS:

   - Andreas and Alice, from Samsung and Google respectively, are
     joining as reviewers of the "RUST" entry.

  As well as a few other minor changes and cleanups"

* tag 'rust-6.6' of https://github.com/Rust-for-Linux/linux: (42 commits)
  rust: init: update expanded macro explanation
  rust: init: add `{pin_}chain` functions to `{Pin}Init`
  rust: init: make `PinInit` a supertrait of `Init`
  rust: init: implement `Zeroable` for `UnsafeCell` and `Opaque`
  rust: init: add support for arbitrary paths in init macros
  rust: init: add functions to create array initializers
  rust: init: add `..Zeroable::zeroed()` syntax for zeroing all missing fields
  rust: init: make initializer values inaccessible after initializing
  rust: init: wrap type checking struct initializers in a closure
  rust: init: make guards in the init macros hygienic
  rust: add derive macro for `Zeroable`
  rust: init: make `#[pin_data]` compatible with conditional compilation of fields
  rust: init: consolidate init macros
  docs: rust: clarify what 'rustup override' does
  docs: rust: update instructions for obtaining 'core' source
  docs: rust: add command line to rust-analyzer section
  scripts: generate_rust_analyzer: provide `cfg`s for `core` and `alloc`
  rust: bindgen: upgrade to 0.65.1
  rust: enable `no_mangle_with_rust_abi` Clippy lint
  rust: upgrade to Rust 1.71.1
  ...