Commit graph

14 commits

Author SHA1 Message Date
Linus Torvalds
352af6a011 Rust changes for v6.17
Toolchain and infrastructure:
 
  - Enable a set of Clippy lints: 'ptr_as_ptr', 'ptr_cast_constness',
    'as_ptr_cast_mut', 'as_underscore', 'cast_lossless' and 'ref_as_ptr'.
 
    These are intended to avoid type casts with the 'as' operator, which
    are quite powerful, into restricted variants that are less powerful
    and thus should help to avoid mistakes.
 
  - Remove the 'author' key now that most instances were moved to the
    plural one in the previous cycle.
 
 'kernel' crate:
 
  - New 'bug' module: add 'warn_on!' macro which reuses the existing
    'BUG'/'WARN' infrastructure, i.e. it respects the usual sysctls and
    kernel parameters:
 
        warn_on!(value == 42);
 
    To avoid duplicating the assembly code, the same strategy is followed
    as for the static branch code in order to share the assembly between
    both C and Rust. This required a few rearrangements on C arch headers
    -- the existing C macros should still generate the same outputs, thus
    no functional change expected there.
 
  - 'workqueue' module: add delayed work items, including a 'DelayedWork'
    struct, a 'impl_has_delayed_work!' macro and an 'enqueue_delayed'
    method, e.g.:
 
        /// Enqueue the struct for execution on the system workqueue,
        /// where its value will be printed 42 jiffies later.
        fn print_later(value: Arc<MyStruct>) {
            let _ = workqueue::system().enqueue_delayed(value, 42);
        }
 
  - New 'bits' module: add support for 'bit' and 'genmask' functions,
    with runtime- and compile-time variants, e.g.:
 
        static_assert!(0b00010000 == bit_u8(4));
        static_assert!(0b00011110 == genmask_u8(1..=4));
 
        assert!(checked_bit_u32(u32::BITS).is_none());
 
  - 'uaccess' module: add 'UserSliceReader::strcpy_into_buf', which reads
    NUL-terminated strings from userspace into a '&CStr'.
 
    Introduce 'UserPtr' newtype, similar in purpose to '__user' in C, to
    minimize mistakes handling userspace pointers, including mixing them
    up with integers and leaking them via the 'Debug' trait. Add it to
    the prelude, too.
 
  - Start preparations for the replacement of our custom 'CStr' type
    with the analogous type in the 'core' standard library. This will
    take place across several cycles to make it easier. For this one,
    it includes a new 'fmt' module, using upstream method names and some
    other cleanups.
 
    Replace 'fmt!' with a re-export, which helps Clippy lint properly,
    and clean up the found 'uninlined-format-args' instances.
 
  - 'dma' module:
 
    - Clarify wording and be consistent in 'coherent' nomenclature.
 
    - Convert the 'read!()' and 'write!()' macros to return a 'Result'.
 
    - Add 'as_slice()', 'write()' methods in 'CoherentAllocation'.
 
    - Expose 'count()' and 'size()' in 'CoherentAllocation' and add the
      corresponding type invariants.
 
    - Implement 'CoherentAllocation::dma_handle_with_offset()'.
 
  - 'time' module:
 
    - Make 'Instant' generic over clock source. This allows the compiler
      to assert that arithmetic expressions involving the 'Instant' use
      'Instants' based on the same clock source.
 
    - Make 'HrTimer' generic over the timer mode. 'HrTimer' timers take a
      'Duration' or an 'Instant' when setting the expiry time, depending
      on the timer mode. With this change, the compiler can check the
      type matches the timer mode.
 
    - Add an abstraction for 'fsleep'. 'fsleep' is a flexible sleep
      function that will select an appropriate sleep method depending on
      the requested sleep time.
 
    - Avoid 64-bit divisions on 32-bit hardware when calculating
      timestamps.
 
    - Seal the 'HrTimerMode' trait. This prevents users of the
      'HrTimerMode' from implementing the trait on their own types.
 
    - Pass the correct timer mode ID to 'hrtimer_start_range_ns()'.
 
  - 'list' module: remove 'OFFSET' constants, allowing to remove pointer
    arithmetic; now 'impl_list_item!' invokes 'impl_has_list_links!' or
    'impl_has_list_links_self_ptr!'. Other simplifications too.
 
  - 'types' module: remove 'ForeignOwnable::PointedTo' in favor of a
    constant, which avoids exposing the type of the opaque pointer, and
    require 'into_foreign' to return non-null.
 
    Remove the 'Either<L, R>' type as well. It is unused, and we want to
    encourage the use of custom enums for concrete use cases.
 
  - 'sync' module: implement 'Borrow' and 'BorrowMut' for 'Arc' types
    to allow them to be used in generic APIs.
 
  - 'alloc' module: implement 'Borrow' and 'BorrowMut' for 'Box<T, A>';
     and 'Borrow', 'BorrowMut' and 'Default' for 'Vec<T, A>'.
 
  - 'Opaque' type: add 'cast_from' method to perform a restricted cast
    that cannot change the inner type and use it in callers of
    'container_of!'. Rename 'raw_get' to 'cast_into' to match it.
 
  - 'rbtree' module: add 'is_empty' method.
 
  - 'sync' module: new 'aref' submodule to hold 'AlwaysRefCounted' and
    'ARef', which are moved from the too general 'types' module which we
    want to reduce or eventually remove. Also fix a safety comment in
    'static_lock_class'.
 
 'pin-init' crate:
 
  - Add 'impl<T, E> [Pin]Init<T, E> for Result<T, E>', so results are now
    (pin-)initializers.
 
  - Add 'Zeroable::init_zeroed()' that delegates to 'init_zeroed()'.
 
  - New 'zeroed()', a safe version of 'mem::zeroed()' and also provide
    it via 'Zeroable::zeroed()'.
 
  - Implement 'Zeroable' for 'Option<&T>', 'Option<&mut T>' and for
    'Option<[unsafe] [extern "abi"] fn(...args...) -> ret>' for '"Rust"'
    and '"C"' ABIs and up to 20 arguments.
 
  - Changed blanket impls of 'Init' and 'PinInit' from 'impl<T, E>
    [Pin]Init<T, E> for T' to 'impl<T> [Pin]Init<T> for T'.
 
  - Renamed 'zeroed()' to 'init_zeroed()'.
 
  - Upstream dev news: improve CI more to deny warnings, use
    '--all-targets'. Check the synchronization status of the two '-next'
    branches in upstream and the kernel.
 
 MAINTAINERS:
 
  - Add Vlastimil Babka, Liam R. Howlett, Uladzislau Rezki and Lorenzo
    Stoakes as reviewers (thanks everyone).
 
 And a few other cleanups and improvements.
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Merge tag 'rust-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

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

   - Enable a set of Clippy lints: 'ptr_as_ptr', 'ptr_cast_constness',
     'as_ptr_cast_mut', 'as_underscore', 'cast_lossless' and
     'ref_as_ptr'

     These are intended to avoid type casts with the 'as' operator,
     which are quite powerful, into restricted variants that are less
     powerful and thus should help to avoid mistakes

   - Remove the 'author' key now that most instances were moved to the
     plural one in the previous cycle

  'kernel' crate:

   - New 'bug' module: add 'warn_on!' macro which reuses the existing
     'BUG'/'WARN' infrastructure, i.e. it respects the usual sysctls and
     kernel parameters:

         warn_on!(value == 42);

     To avoid duplicating the assembly code, the same strategy is
     followed as for the static branch code in order to share the
     assembly between both C and Rust

     This required a few rearrangements on C arch headers -- the
     existing C macros should still generate the same outputs, thus no
     functional change expected there

   - 'workqueue' module: add delayed work items, including a
     'DelayedWork' struct, a 'impl_has_delayed_work!' macro and an
     'enqueue_delayed' method, e.g.:

         /// Enqueue the struct for execution on the system workqueue,
         /// where its value will be printed 42 jiffies later.
         fn print_later(value: Arc<MyStruct>) {
             let _ = workqueue::system().enqueue_delayed(value, 42);
         }

   - New 'bits' module: add support for 'bit' and 'genmask' functions,
     with runtime- and compile-time variants, e.g.:

         static_assert!(0b00010000 == bit_u8(4));
         static_assert!(0b00011110 == genmask_u8(1..=4));

         assert!(checked_bit_u32(u32::BITS).is_none());

   - 'uaccess' module: add 'UserSliceReader::strcpy_into_buf', which
     reads NUL-terminated strings from userspace into a '&CStr'

     Introduce 'UserPtr' newtype, similar in purpose to '__user' in C,
     to minimize mistakes handling userspace pointers, including mixing
     them up with integers and leaking them via the 'Debug' trait. Add
     it to the prelude, too

   - Start preparations for the replacement of our custom 'CStr' type
     with the analogous type in the 'core' standard library. This will
     take place across several cycles to make it easier. For this one,
     it includes a new 'fmt' module, using upstream method names and
     some other cleanups

     Replace 'fmt!' with a re-export, which helps Clippy lint properly,
     and clean up the found 'uninlined-format-args' instances

   - 'dma' module:

      - Clarify wording and be consistent in 'coherent' nomenclature

      - Convert the 'read!()' and 'write!()' macros to return a 'Result'

      - Add 'as_slice()', 'write()' methods in 'CoherentAllocation'

      - Expose 'count()' and 'size()' in 'CoherentAllocation' and add
        the corresponding type invariants

      - Implement 'CoherentAllocation::dma_handle_with_offset()'

   - 'time' module:

      - Make 'Instant' generic over clock source. This allows the
        compiler to assert that arithmetic expressions involving the
        'Instant' use 'Instants' based on the same clock source

      - Make 'HrTimer' generic over the timer mode. 'HrTimer' timers
        take a 'Duration' or an 'Instant' when setting the expiry time,
        depending on the timer mode. With this change, the compiler can
        check the type matches the timer mode

      - Add an abstraction for 'fsleep'. 'fsleep' is a flexible sleep
        function that will select an appropriate sleep method depending
        on the requested sleep time

      - Avoid 64-bit divisions on 32-bit hardware when calculating
        timestamps

      - Seal the 'HrTimerMode' trait. This prevents users of the
        'HrTimerMode' from implementing the trait on their own types

      - Pass the correct timer mode ID to 'hrtimer_start_range_ns()'

   - 'list' module: remove 'OFFSET' constants, allowing to remove
     pointer arithmetic; now 'impl_list_item!' invokes
     'impl_has_list_links!' or 'impl_has_list_links_self_ptr!'. Other
     simplifications too

   - 'types' module: remove 'ForeignOwnable::PointedTo' in favor of a
     constant, which avoids exposing the type of the opaque pointer, and
     require 'into_foreign' to return non-null

     Remove the 'Either<L, R>' type as well. It is unused, and we want
     to encourage the use of custom enums for concrete use cases

   - 'sync' module: implement 'Borrow' and 'BorrowMut' for 'Arc' types
     to allow them to be used in generic APIs

   - 'alloc' module: implement 'Borrow' and 'BorrowMut' for 'Box<T, A>';
     and 'Borrow', 'BorrowMut' and 'Default' for 'Vec<T, A>'

   - 'Opaque' type: add 'cast_from' method to perform a restricted cast
     that cannot change the inner type and use it in callers of
     'container_of!'. Rename 'raw_get' to 'cast_into' to match it

   - 'rbtree' module: add 'is_empty' method

   - 'sync' module: new 'aref' submodule to hold 'AlwaysRefCounted' and
     'ARef', which are moved from the too general 'types' module which
     we want to reduce or eventually remove. Also fix a safety comment
     in 'static_lock_class'

  'pin-init' crate:

   - Add 'impl<T, E> [Pin]Init<T, E> for Result<T, E>', so results are
     now (pin-)initializers

   - Add 'Zeroable::init_zeroed()' that delegates to 'init_zeroed()'

   - New 'zeroed()', a safe version of 'mem::zeroed()' and also provide
     it via 'Zeroable::zeroed()'

   - Implement 'Zeroable' for 'Option<&T>', 'Option<&mut T>' and for
     'Option<[unsafe] [extern "abi"] fn(...args...) -> ret>' for
     '"Rust"' and '"C"' ABIs and up to 20 arguments

   - Changed blanket impls of 'Init' and 'PinInit' from 'impl<T, E>
     [Pin]Init<T, E> for T' to 'impl<T> [Pin]Init<T> for T'

   - Renamed 'zeroed()' to 'init_zeroed()'

   - Upstream dev news: improve CI more to deny warnings, use
     '--all-targets'. Check the synchronization status of the two
     '-next' branches in upstream and the kernel

  MAINTAINERS:

   - Add Vlastimil Babka, Liam R. Howlett, Uladzislau Rezki and Lorenzo
     Stoakes as reviewers (thanks everyone)

  And a few other cleanups and improvements"

* tag 'rust-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (76 commits)
  rust: Add warn_on macro
  arm64/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  riscv/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  x86/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  rust: kernel: move ARef and AlwaysRefCounted to sync::aref
  rust: sync: fix safety comment for `static_lock_class`
  rust: types: remove `Either<L, R>`
  rust: kernel: use `core::ffi::CStr` method names
  rust: str: add `CStr` methods matching `core::ffi::CStr`
  rust: str: remove unnecessary qualification
  rust: use `kernel::{fmt,prelude::fmt!}`
  rust: kernel: add `fmt` module
  rust: kernel: remove `fmt!`, fix clippy::uninlined-format-args
  scripts: rust: emit path candidates in panic message
  scripts: rust: replace length checks with match
  rust: list: remove nonexistent generic parameter in link
  rust: bits: add support for bits/genmask macros
  rust: list: remove OFFSET constants
  rust: list: add `impl_list_item!` examples
  rust: list: use fully qualified path
  ...
2025-08-03 13:49:10 -07:00
Miguel Ojeda
7498159226 rust: use #[used(compiler)] to fix build and modpost with Rust >= 1.89.0
Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails
to build the `rusttest` target due to undefined references such as:

    kernel...-cgu.0:(.text....+0x116): undefined reference to
    `rust_helper_kunit_get_current_test'

Moreover, tooling like `modpost` gets confused:

    WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o
    ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o

The reason behind both issues is that the Rust compiler will now [1]
treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]`
for our targets. This means that the retain section flag (`R`,
`SHF_GNU_RETAIN`) will be used and that they will be marked as `unique`
too, with different IDs. In turn, that means we end up with undefined
references that did not get discarded in `rusttest` and that multiple
`.modinfo` sections are generated, which confuse tooling like `modpost`
because they only expect one.

Thus start using `#[used(compiler)]` to keep the previous behavior
and to be explicit about what we want. Sadly, it is an unstable feature
(`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good
news is that it has been available for a long time (Rust >= 1.60) [3].

The changes should also be fine for previous Rust versions, since they
behave the same way as before [4].

Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]`
since those still behave like `#[used(compiler)]`, but of course it is
not really what we want to express, and it requires other changes to
avoid symbol conflicts.

Cc: David Wood <david@davidtw.co>
Cc: Wesley Wiser <wwiser@gmail.com>
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://github.com/rust-lang/rust/pull/140872 [1]
Link: https://github.com/rust-lang/rust/issues/93798 [2]
Link: https://github.com/rust-lang/rust/pull/91504 [3]
Link: https://godbolt.org/z/sxzWTMfzW [4]
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-07-14 23:30:44 +02:00
Jesung Yang
5d4ffc531a rust: kunit: use crate-level mapping for c_void
Remove `use core::ffi::c_void`, which shadows `kernel::ffi::c_void`
brought in via `use crate::prelude::*`, to maintain consistency and
centralize the abstraction.

Since `kernel::ffi::c_void` is a straightforward re-export of
`core::ffi::c_void`, both are functionally equivalent. However, using
`kernel::ffi::c_void` improves consistency across the kernel's Rust code
and provides a unified reference point in case the definition ever needs
to change, even if such a change is unlikely.

Reviewed-by: Benno Lossin <lossin@kernel.org>
Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089/topic/x/near/520452733
Signed-off-by: Jesung Yang <y.j3ms.n@gmail.com>
Link: https://lore.kernel.org/r/20250528174953.2948570-1-y.j3ms.n@gmail.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-06-24 00:55:22 +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
Miguel Ojeda
897d1df653 rust: add kunit_tests to the prelude
It is convenient to have certain things in the `kernel` prelude, and
means kernel developers will find it even easier to start writing tests.

And, anyway, nobody should need to use this identifier for anything else.

Thus add it to the prelude.

Reviewed-by: David Gow <davidgow@google.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250502215133.1923676-4-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-27 20:09:59 +02:00
Miguel Ojeda
950b306c29 rust: kunit: support checked -> Results in KUnit #[test]s
Currently, return values of KUnit `#[test]` functions are ignored.

Thus introduce support for `-> Result` functions by checking their
returned values.

At the same time, require that test functions return `()` or `Result<T,
E>`, which should avoid mistakes, especially with non-`#[must_use]`
types. Other types can be supported in the future if needed.

With this, a failing test like:

    #[test]
    fn my_test() -> Result {
        f()?;
        Ok(())
    }

will output:

    [    3.744214]     KTAP version 1
    [    3.744287]     # Subtest: my_test_suite
    [    3.744378]     # speed: normal
    [    3.744399]     1..1
    [    3.745817]     # my_test: ASSERTION FAILED at rust/kernel/lib.rs:321
    [    3.745817]     Expected is_test_result_ok(my_test()) to be true, but is false
    [    3.747152]     # my_test.speed: normal
    [    3.747199]     not ok 1 my_test
    [    3.747345] not ok 4 my_test_suite

Reviewed-by: David Gow <davidgow@google.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250502215133.1923676-3-ojeda@kernel.org
[ Used `::kernel` for paths. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-27 20:09:59 +02:00
Miguel Ojeda
36174d16f3 rust: kunit: support KUnit-mapped assert! macros in #[test]s
The KUnit `#[test]` support that landed recently is very basic and does
not map the `assert*!` macros into KUnit like the doctests do, so they
panic at the moment.

Thus implement the custom mapping in a similar way to doctests, reusing
the infrastructure there.

In Rust 1.88.0, the `file()` method in `Span` may be stable [1]. However,
it was changed recently (from `SourceFile`), so we need to do something
different in previous versions. Thus create a helper for it and use it
to get the path.

With this, a failing test suite like:

    #[kunit_tests(my_test_suite)]
    mod tests {
        use super::*;

        #[test]
        fn my_first_test() {
            assert_eq!(42, 43);
        }

        #[test]
        fn my_second_test() {
            assert!(42 >= 43);
        }
    }

will properly map back to KUnit, printing something like:

    [    1.924325]     KTAP version 1
    [    1.924421]     # Subtest: my_test_suite
    [    1.924506]     # speed: normal
    [    1.924525]     1..2
    [    1.926385]     # my_first_test: ASSERTION FAILED at rust/kernel/lib.rs:251
    [    1.926385]     Expected 42 == 43 to be true, but is false
    [    1.928026]     # my_first_test.speed: normal
    [    1.928075]     not ok 1 my_first_test
    [    1.928723]     # my_second_test: ASSERTION FAILED at rust/kernel/lib.rs:256
    [    1.928723]     Expected 42 >= 43 to be true, but is false
    [    1.929834]     # my_second_test.speed: normal
    [    1.929868]     not ok 2 my_second_test
    [    1.930032] # my_test_suite: pass:0 fail:2 skip:0 total:2
    [    1.930153] # Totals: pass:0 fail:2 skip:0 total

Link: https://github.com/rust-lang/rust/pull/140514 [1]
Reviewed-by: David Gow <davidgow@google.com>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20250502215133.1923676-2-ojeda@kernel.org
[ Required `KUNIT=y` like for doctests. Used the `cfg_attr` from the
  TODO comment and clarified its comment now that the stabilization is
  in beta and thus quite likely stable in Rust 1.88.0. Simplified the
  `new_body` code by introducing a new variable. Added
  `#[allow(clippy::incompatible_msrv)]`. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-27 20:07:09 +02:00
Igor Korotin
de7cd3e4d6 rust: use absolute paths in macros referencing core and kernel
Macros and auto-generated code should use absolute paths, `::core::...`
and `::kernel::...`, for core and kernel references.

This prevents issues where user-defined modules named `core` or `kernel`
could be picked up instead of the `core` or `kernel` crates.

Thus clean some references up.

Suggested-by: Benno Lossin <benno.lossin@proton.me>
Closes: https://github.com/Rust-for-Linux/linux/issues/1150
Signed-off-by: Igor Korotin <igor.korotin.linux@gmail.com>
Reviewed-by: Benno Lossin <lossin@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250519164615.3310844-1-igor.korotin.linux@gmail.com
[ Applied `rustfmt`. Reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-05-23 00:12:14 +02:00
José Expósito
100af58c8d rust: kunit: allow to know if we are in a test
In some cases, we need to call test-only code from outside the test
case, for example, to mock a function or a module.

In order to check whether we are in a test or not, we need to test if
`CONFIG_KUNIT` is set.
Unfortunately, we cannot rely only on this condition because:
- a test could be running in another thread,
- some distros compile KUnit in production kernels, so checking at runtime
  that `current->kunit_test != NULL` is required.

Forturately, KUnit provides an optimised check in
`kunit_get_current_test()`, which checks CONFIG_KUNIT, a global static
key, and then the current thread's running KUnit test.

Add a safe wrapper function around this to know whether or not we are in
a KUnit test and examples showing how to mock a function and a module.

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Co-developed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Co-developed-by: David Gow <davidgow@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/r/20250307090103.918788-4-davidgow@google.com
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-20 12:27:05 +01:00
José Expósito
c001045289 rust: macros: add macro to easily run KUnit tests
Add a new procedural macro (`#[kunit_tests(kunit_test_suit_name)]`) to
run KUnit tests using a user-space like syntax.

The macro, that should be used on modules, transforms every `#[test]`
in a `kunit_case!` and adds a `kunit_unsafe_test_suite!` registering
all of them.

The only difference with user-space tests is that instead of using
`#[cfg(test)]`, `#[kunit_tests(kunit_test_suit_name)]` is used.

Note that `#[cfg(CONFIG_KUNIT)]` is added so the test module is not
compiled when `CONFIG_KUNIT` is set to `n`.

Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Co-developed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Co-developed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Tamir Duberstein <tamird@gmail.com>
Signed-off-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/r/20250307090103.918788-3-davidgow@google.com
[ Removed spurious (in rendered form) newline in docs. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-20 12:26:54 +01:00
José Expósito
22097b966f rust: kunit: add KUnit case and suite macros
Add a couple of Rust const functions and macros to allow to develop
KUnit tests without relying on generated C code:

 - The `kunit_unsafe_test_suite!` Rust macro is similar to the
   `kunit_test_suite` C macro. It requires a NULL-terminated array of
   test cases (see below).
 - The `kunit_case` Rust function is similar to the `KUNIT_CASE` C macro.
   It generates as case from the name and function.
 - The `kunit_case_null` Rust function generates a NULL test case, which
   is to be used as delimiter in `kunit_test_suite!`.

While these functions and macros can be used on their own, a future
patch will introduce another macro to create KUnit tests using a
user-space like syntax.

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Co-developed-by: Matt Gilbride <mattgilbride@google.com>
Signed-off-by: Matt Gilbride <mattgilbride@google.com>
Co-developed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Co-developed-by: David Gow <davidgow@google.com>
Signed-off-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/r/20250307090103.918788-2-davidgow@google.com
[ Applied Markdown in comment. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2025-03-20 12:26:42 +01:00
Miguel Ojeda
05cef2c4a4 rust: kunit: use C-string literals to clean warning
Starting with upstream Rust commit a5e3a3f9b6bd ("move
`manual_c_str_literals` to complexity"), to be released in Rust 1.83.0
[1], Clippy now warns on `manual_c_str_literals` by default, e.g.:

    error: manually constructing a nul-terminated string
      --> rust/kernel/kunit.rs:21:13
       |
    21 |             b"\x013%pA\0".as_ptr() as _,
       |             ^^^^^^^^^^^^^ help: use a `c""` literal: `c"\x013%pA"`
       |
       = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_c_str_literals
       = note: `-D clippy::manual-c-str-literals` implied by `-D warnings`
       = help: to override `-D warnings` add `#[allow(clippy::manual_c_str_literals)]`

Apply the suggestion to clean up the warnings.

Link: https://github.com/rust-lang/rust-clippy/pull/13263 [1]
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20240927164414.560906-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2024-10-01 23:46:42 +02:00
Miguel Ojeda
bc2e7d5c29 rust: support srctree-relative links
Some of our links use relative paths in order to point to files in the
source tree, e.g.:

    //! C header: [`include/linux/printk.h`](../../../../include/linux/printk.h)
    /// [`struct mutex`]: ../../../../include/linux/mutex.h

These are problematic because they are hard to maintain and do not support
`O=` builds.

Instead, provide support for `srctree`-relative links, e.g.:

    //! C header: [`include/linux/printk.h`](srctree/include/linux/printk.h)
    /// [`struct mutex`]: srctree/include/linux/mutex.h

The links are fixed after `rustdoc` generation to be based on the absolute
path to the source tree.

Essentially, this is the automatic version of Tomonori's fix [1],
suggested by Gary [2].

Suggested-by: Gary Guo <gary@garyguo.net>
Reported-by: FUJITA Tomonori <fujita.tomonori@gmail.com>
Closes: https://lore.kernel.org/r/20231026.204058.2167744626131849993.fujita.tomonori@gmail.com [1]
Fixes: 48fadf4400 ("docs: Move rustdoc output, cross-reference it")
Link: https://lore.kernel.org/rust-for-linux/20231026154525.6d14b495@eugeo/ [2]
Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20231215235428.243211-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2023-12-21 20:54:17 +01:00
Miguel Ojeda
a66d733da8 rust: support running Rust documentation tests as KUnit ones
Rust has documentation tests: these are typically examples of
usage of any item (e.g. function, struct, module...).

They are very convenient because they are just written
alongside the documentation. For instance:

    /// Sums two numbers.
    ///
    /// ```
    /// assert_eq!(mymod::f(10, 20), 30);
    /// ```
    pub fn f(a: i32, b: i32) -> i32 {
        a + b
    }

In userspace, the tests are collected and run via `rustdoc`.
Using the tool as-is would be useful already, since it allows
to compile-test most tests (thus enforcing they are kept
in sync with the code they document) and run those that do not
depend on in-kernel APIs.

However, by transforming the tests into a KUnit test suite,
they can also be run inside the kernel. Moreover, the tests
get to be compiled as other Rust kernel objects instead of
targeting userspace.

On top of that, the integration with KUnit means the Rust
support gets to reuse the existing testing facilities. For
instance, the kernel log would look like:

    KTAP version 1
    1..1
        KTAP version 1
        # Subtest: rust_doctests_kernel
        1..59
        # rust_doctest_kernel_build_assert_rs_0.location: rust/kernel/build_assert.rs:13
        ok 1 rust_doctest_kernel_build_assert_rs_0
        # rust_doctest_kernel_build_assert_rs_1.location: rust/kernel/build_assert.rs:56
        ok 2 rust_doctest_kernel_build_assert_rs_1
        # rust_doctest_kernel_init_rs_0.location: rust/kernel/init.rs:122
        ok 3 rust_doctest_kernel_init_rs_0
        ...
        # rust_doctest_kernel_types_rs_2.location: rust/kernel/types.rs:150
        ok 59 rust_doctest_kernel_types_rs_2
    # rust_doctests_kernel: pass:59 fail:0 skip:0 total:59
    # Totals: pass:59 fail:0 skip:0 total:59
    ok 1 rust_doctests_kernel

Therefore, add support for running Rust documentation tests
in KUnit. Some other notes about the current implementation
and support follow.

The transformation is performed by a couple scripts written
as Rust hostprogs.

Tests using the `?` operator are also supported as usual, e.g.:

    /// ```
    /// # use kernel::{spawn_work_item, workqueue};
    /// spawn_work_item!(workqueue::system(), || pr_info!("x"))?;
    /// # Ok::<(), Error>(())
    /// ```

The tests are also compiled with Clippy under `CLIPPY=1`, just
like normal code, thus also benefitting from extra linting.

The names of the tests are currently automatically generated.
This allows to reduce the burden for documentation writers,
while keeping them fairly stable for bisection. This is an
improvement over the `rustdoc`-generated names, which include
the line number; but ideally we would like to get `rustdoc` to
provide the Rust item path and a number (for multiple examples
in a single documented Rust item).

In order for developers to easily see from which original line
a failed doctests came from, a KTAP diagnostic line is printed
to the log, containing the location (file and line) of the
original test (i.e. instead of the location in the generated
Rust file):

    # rust_doctest_kernel_types_rs_2.location: rust/kernel/types.rs:150

This line follows the syntax for declaring test metadata in the
proposed KTAP v2 spec [1], which may be used for the proposed
KUnit test attributes API [2]. Thus hopefully this will make
migration easier later on (suggested by David [3]).

The original line in that test attribute is figured out by
providing an anchor (suggested by Boqun [4]). The original file
is found by walking the filesystem, checking directory prefixes
to reduce the amount of combinations to check, and it is only
done once per file. Ambiguities are detected and reported.

A notable difference from KUnit C tests is that the Rust tests
appear to assert using the usual `assert!` and `assert_eq!`
macros from the Rust standard library (`core`). We provide
a custom version that forwards the call to KUnit instead.
Importantly, these macros do not require passing context,
unlike the KUnit C ones (i.e. `struct kunit *`). This makes
them easier to use, and readers of the documentation do not need
to care about which testing framework is used. In addition, it
may allow us to test third-party code more easily in the future.

However, a current limitation is that KUnit does not support
assertions in other tasks. Thus we presently simply print an
error to the kernel log if an assertion actually failed. This
should be revisited to properly fail the test, perhaps saving
the context somewhere else, or letting KUnit handle it.

Link: https://lore.kernel.org/lkml/20230420205734.1288498-1-rmoar@google.com/ [1]
Link: https://lore.kernel.org/linux-kselftest/20230707210947.1208717-1-rmoar@google.com/ [2]
Link: https://lore.kernel.org/rust-for-linux/CABVgOSkOLO-8v6kdAGpmYnZUb+LKOX0CtYCo-Bge7r_2YTuXDQ@mail.gmail.com/ [3]
Link: https://lore.kernel.org/rust-for-linux/ZIps86MbJF%2FiGIzd@boqun-archlinux/ [4]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
2023-07-19 09:32:53 -06:00