linux.git/rust/kernel/types.rs, branch v6.12.80

rust: use custom FFI integer types

2025-03-13T12:01:49+00:00

commit d072acda4862f095ec9056979b654cc06a22cc68 upstream.

Currently FFI integer types are defined in libcore. This commit creates
the `ffi` crate and asks bindgen to use that crate for FFI integer types
instead of `core::ffi`.

This commit is preparatory and no type changes are made in this commit
yet.

Signed-off-by: Gary Guo 
Link: https://lore.kernel.org/r/20240913213041.395655-4-gary@garyguo.net
[ Added `rustdoc`, `rusttest` and KUnit tests support. Rebased on top of
  `rust-next` (e.g. migrated more `core::ffi` cases). Reworded crate
  docs slightly and formatted. - Miguel ]
Signed-off-by: Miguel Ojeda 
Signed-off-by: Greg Kroah-Hartman

rust: treewide: switch to the kernel `Vec` type

2025-03-13T12:01:46+00:00

commit 58eff8e872bd04ccb3adcf99aec7334ffad06cfd upstream.

Now that we got the kernel `Vec` in place, convert all existing `Vec`
users to make use of it.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-20-dakr@kernel.org
[ Converted `kasan_test_rust.rs` too, as discussed. - Miguel ]
Signed-off-by: Miguel Ojeda 
Signed-off-by: Greg Kroah-Hartman

rust: alloc: remove extension of std's `Box`

2025-03-13T12:01:45+00:00

commit e8c6ccdbcaaf31f26c0fffd4073edd0b0147cdc6 upstream.

Now that all existing `Box` users were moved to the kernel `Box` type,
remove the `BoxExt` extension and all other related extensions.

Reviewed-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Reviewed-by: Gary Guo 
Signed-off-by: Danilo Krummrich 
Link: https://lore.kernel.org/r/20241004154149.93856-14-dakr@kernel.org
Signed-off-by: Miguel Ojeda 
Signed-off-by: Greg Kroah-Hartman

rust: enable `clippy::ignored_unit_patterns` lint

2025-03-13T12:01:41+00:00

commit 3fcc23397628c2357dbe66df59644e09f72ac725 upstream.

In Rust 1.73.0, Clippy introduced the `ignored_unit_patterns` lint [1]:

> Matching with `()` explicitly instead of `_` outlines the fact that
> the pattern contains no data. Also it would detect a type change
> that `_` would ignore.

There is only a single case that requires a change:

    error: matching over `()` is more explicit
       --> rust/kernel/types.rs:176:45
        |
    176 |         ScopeGuard::new_with_data((), move |_| cleanup())
        |                                             ^ help: use `()` instead of `_`: `()`
        |
        = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ignored_unit_patterns
        = note: requested on the command line with `-D clippy::ignored-unit-patterns`

Thus clean it up and enable the lint -- no functional change intended.

Link: https://rust-lang.github.io/rust-clippy/master/index.html#/ignored_unit_patterns [1]
Reviewed-by: Alice Ryhl 
Reviewed-by: Trevor Gross 
Tested-by: Gary Guo 
Reviewed-by: Gary Guo 
Link: https://lore.kernel.org/r/20240904204347.168520-8-ojeda@kernel.org
Signed-off-by: Miguel Ojeda 
Signed-off-by: Greg Kroah-Hartman

rust: enable `clippy::undocumented_unsafe_blocks` lint

2025-03-13T12:01:41+00:00

commit db4f72c904cb116e2bf56afdd67fc5167a607a7b upstream.

Checking that we are not missing any `// SAFETY` comments in our `unsafe`
blocks is something we have wanted to do for a long time, as well as
cleaning up the remaining cases that were not documented [1].

Back when Rust for Linux started, this was something that could have
been done via a script, like Rust's `tidy`. Soon after, in Rust 1.58.0,
Clippy implemented the `undocumented_unsafe_blocks` lint [2].

Even though the lint has a few false positives, e.g. in some cases where
attributes appear between the comment and the `unsafe` block [3], there
are workarounds and the lint seems quite usable already.

Thus enable the lint now.

We still have a few cases to clean up, so just allow those for the moment
by writing a `TODO` comment -- some of those may be good candidates for
new contributors.

Link: https://github.com/Rust-for-Linux/linux/issues/351 [1]
Link: https://rust-lang.github.io/rust-clippy/master/#/undocumented_unsafe_blocks [2]
Link: https://github.com/rust-lang/rust-clippy/issues/13189 [3]
Reviewed-by: Alice Ryhl 
Reviewed-by: Trevor Gross 
Tested-by: Gary Guo 
Reviewed-by: Gary Guo 
Link: https://lore.kernel.org/r/20240904204347.168520-5-ojeda@kernel.org
Signed-off-by: Miguel Ojeda 
Signed-off-by: Greg Kroah-Hartman

rust: types: avoid repetition in `{As,From}Bytes` impls

2025-03-13T12:01:40+00:00

commit 567cdff53e71de56ae67eaf4309db38778b7bcd3 upstream.

In order to provide `// SAFETY` comments for every `unsafe impl`, we would
need to repeat them, which is not very useful and would be harder to read.

We could perhaps allow the lint (ideally within a small module), but we
can take the chance to avoid the repetition of the `impl`s themselves
too by using a small local macro, like in other places where we have
had to do this sort of thing.

Thus add the straightforward `impl_{from,as}bytes!` macros and use them
to implement `FromBytes`.

This, in turn, will allow us in the next patch to place a `// SAFETY`
comment that defers to the actual invocation of the macro.

Reviewed-by: Alice Ryhl 
Reviewed-by: Trevor Gross 
Tested-by: Gary Guo 
Reviewed-by: Gary Guo 
Link: https://lore.kernel.org/r/20240904204347.168520-4-ojeda@kernel.org
Signed-off-by: Miguel Ojeda 
Signed-off-by: Greg Kroah-Hartman

rust: types: add `ARef::into_raw`

2024-08-25T12:44:39+00:00

Add a method for `ARef` that is analogous to `Arc::into_raw`. It is the
inverse operation of `ARef::from_raw`, and allows you to convert the
`ARef` back into a raw pointer while retaining ownership of the
refcount.

This new function will be used by [1] for converting the type in an
`ARef` using `ARef::from_raw(ARef::into_raw(me).cast())`. Alice has
also needed the same function for other use-cases in the past, but [1]
is the first to go upstream.

This was implemented independently by Kartik and Alice. The two versions
were merged by Alice, so all mistakes are Alice's.

Link: https://lore.kernel.org/r/20240801-vma-v3-1-db6c1c0afda9@google.com [1]
Link: https://github.com/Rust-for-Linux/linux/issues/1044
Signed-off-by: Kartik Prajapati 
Co-developed-by: Alice Ryhl 
Signed-off-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
[ Reworded to correct the author reference and changed tag to Link
  since it is not a bug. - Miguel ]
Signed-off-by: Miguel Ojeda

rust: types: improve `ForeignOwnable` documentation

2024-08-18T21:10:53+00:00

There are no guarantees for the pointer returned by `into_foreign`.
This is simply because there is no safety documentation stating any
guarantees. Therefore dereferencing and all other operations for that
pointer are not allowed in a general context (i.e. when the concrete
type implementing the trait is not known).
This might be confusing, therefore add normal documentation to state
that there are no guarantees given for the pointer.

Signed-off-by: Benno Lossin 
Reviewed-by: Alice Ryhl 
Link: https://lore.kernel.org/r/20240730182251.1466684-1-benno.lossin@proton.me
Signed-off-by: Miguel Ojeda

rust: implement ForeignOwnable for Pin>

2024-08-18T21:10:53+00:00

We already implement ForeignOwnable for Box, but it may be useful to
store pinned data in a ForeignOwnable container. This patch makes that
possible.

This will be used together with upcoming miscdev abstractions, which
Binder will use when binderfs is disabled.

Signed-off-by: Alice Ryhl 
Reviewed-by: Benno Lossin 
Link: https://lore.kernel.org/r/20240730-foreign-ownable-pin-box-v1-1-b1d70cdae541@google.com
Signed-off-by: Miguel Ojeda

rust: uaccess: add typed accessors for userspace pointers

2024-07-08T21:44:01+00:00

Add safe methods for reading and writing Rust values to and from
userspace pointers.

The C methods for copying to/from userspace use a function called
`check_object_size` to verify that the kernel pointer is not dangling.
However, this check is skipped when the length is a compile-time
constant, with the assumption that such cases trivially have a correct
kernel pointer.

In this patch, we apply the same optimization to the typed accessors.
For both methods, the size of the operation is known at compile time to
be size_of of the type being read or written. Since the C side doesn't
provide a variant that skips only this check, we create custom helpers
for this purpose.

The majority of reads and writes to userspace pointers in the Rust
Binder driver uses these accessor methods. Benchmarking has found that
skipping the `check_object_size` check makes a big difference for the
cases being skipped here. (And that the check doesn't make a difference
for the cases that use the raw read/write methods.)

This code is based on something that was originally written by Wedson on
the old rust branch. It was modified by Alice to skip the
`check_object_size` check, and to update various comments, including the
notes about kernel pointers in `WritableToBytes`.

Co-developed-by: Wedson Almeida Filho 
Signed-off-by: Wedson Almeida Filho 
Reviewed-by: Benno Lossin 
Reviewed-by: Boqun Feng 
Reviewed-by: Trevor Gross 
Reviewed-by: Gary Guo 
Signed-off-by: Alice Ryhl 
Link: https://lore.kernel.org/r/20240528-alice-mm-v7-3-78222c31b8f4@google.com
[ Wrapped docs to 100 and added a few intra-doc links. - Miguel ]
Signed-off-by: Miguel Ojeda