From d407317076ce1ce5ec0882f08d619c0dd79a5fbf Mon Sep 17 00:00:00 2001
From: Nell Shamrell-Harrington <nells@linux.microsoft.com>
Date: Wed, 18 Sep 2024 21:20:52 +0000
Subject: rust: types: add examples for the `Either` type

We aim to have examples in all Rust types, thus add basic ones for the
`Either` type.

Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Nell Shamrell-Harrington <nells@linux.microsoft.com>
Tested-by: Dirk Behme <dirk.behme@de.bosch.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Link: https://rust-for-linux.zulipchat.com/#narrow/stream/291565/topic/x/near/467478085
Link: https://lore.kernel.org/r/20240918212052.8790-1-nells@linux.microsoft.com
[ Reworded slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/types.rs | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'rust/kernel/types.rs')

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 9e7ca066355c..e2f3ab11cfda 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -461,6 +461,15 @@ impl<T: AlwaysRefCounted> Drop for ARef<T> {
 }
 
 /// A sum type that always holds either a value of type `L` or `R`.
+///
+/// # Examples
+///
+/// ```
+/// use kernel::types::Either;
+///
+/// let left_value: Either<i32, &str> = Either::Left(7);
+/// let right_value: Either<i32, &str> = Either::Right("right value");
+/// ```
 pub enum Either<L, R> {
     /// Constructs an instance of [`Either`] containing a value of type `L`.
     Left(L),
-- 
cgit v1.2.3


From 567cdff53e71de56ae67eaf4309db38778b7bcd3 Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Wed, 4 Sep 2024 22:43:31 +0200
Subject: rust: types: avoid repetition in `{As,From}Bytes` impls

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 <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Tested-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240904204347.168520-4-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/types.rs | 68 +++++++++++++++++++++++++++-------------------------
 1 file changed, 35 insertions(+), 33 deletions(-)

(limited to 'rust/kernel/types.rs')

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index e2f3ab11cfda..e00c14687eba 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -490,21 +490,22 @@ pub enum Either<L, R> {
 /// All bit-patterns must be valid for this type. This type must not have interior mutability.
 pub unsafe trait FromBytes {}
 
-// SAFETY: All bit patterns are acceptable values of the types below.
-unsafe impl FromBytes for u8 {}
-unsafe impl FromBytes for u16 {}
-unsafe impl FromBytes for u32 {}
-unsafe impl FromBytes for u64 {}
-unsafe impl FromBytes for usize {}
-unsafe impl FromBytes for i8 {}
-unsafe impl FromBytes for i16 {}
-unsafe impl FromBytes for i32 {}
-unsafe impl FromBytes for i64 {}
-unsafe impl FromBytes for isize {}
-// SAFETY: If all bit patterns are acceptable for individual values in an array, then all bit
-// patterns are also acceptable for arrays of that type.
-unsafe impl<T: FromBytes> FromBytes for [T] {}
-unsafe impl<T: FromBytes, const N: usize> FromBytes for [T; N] {}
+macro_rules! impl_frombytes {
+    ($($({$($generics:tt)*})? $t:ty, )*) => {
+        $(unsafe impl$($($generics)*)? FromBytes for $t {})*
+    };
+}
+
+impl_frombytes! {
+    // SAFETY: All bit patterns are acceptable values of the types below.
+    u8, u16, u32, u64, usize,
+    i8, i16, i32, i64, isize,
+
+    // SAFETY: If all bit patterns are acceptable for individual values in an array, then all bit
+    // patterns are also acceptable for arrays of that type.
+    {<T: FromBytes>} [T],
+    {<T: FromBytes, const N: usize>} [T; N],
+}
 
 /// Types that can be viewed as an immutable slice of initialized bytes.
 ///
@@ -523,21 +524,22 @@ unsafe impl<T: FromBytes, const N: usize> FromBytes for [T; N] {}
 /// mutability.
 pub unsafe trait AsBytes {}
 
-// SAFETY: Instances of the following types have no uninitialized portions.
-unsafe impl AsBytes for u8 {}
-unsafe impl AsBytes for u16 {}
-unsafe impl AsBytes for u32 {}
-unsafe impl AsBytes for u64 {}
-unsafe impl AsBytes for usize {}
-unsafe impl AsBytes for i8 {}
-unsafe impl AsBytes for i16 {}
-unsafe impl AsBytes for i32 {}
-unsafe impl AsBytes for i64 {}
-unsafe impl AsBytes for isize {}
-unsafe impl AsBytes for bool {}
-unsafe impl AsBytes for char {}
-unsafe impl AsBytes for str {}
-// SAFETY: If individual values in an array have no uninitialized portions, then the array itself
-// does not have any uninitialized portions either.
-unsafe impl<T: AsBytes> AsBytes for [T] {}
-unsafe impl<T: AsBytes, const N: usize> AsBytes for [T; N] {}
+macro_rules! impl_asbytes {
+    ($($({$($generics:tt)*})? $t:ty, )*) => {
+        $(unsafe impl$($($generics)*)? AsBytes for $t {})*
+    };
+}
+
+impl_asbytes! {
+    // SAFETY: Instances of the following types have no uninitialized portions.
+    u8, u16, u32, u64, usize,
+    i8, i16, i32, i64, isize,
+    bool,
+    char,
+    str,
+
+    // SAFETY: If individual values in an array have no uninitialized portions, then the array
+    // itself does not have any uninitialized portions either.
+    {<T: AsBytes>} [T],
+    {<T: AsBytes, const N: usize>} [T; N],
+}
-- 
cgit v1.2.3


From db4f72c904cb116e2bf56afdd67fc5167a607a7b Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Wed, 4 Sep 2024 22:43:32 +0200
Subject: rust: enable `clippy::undocumented_unsafe_blocks` lint

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 <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Tested-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240904204347.168520-5-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 Makefile                       | 1 +
 mm/kasan/kasan_test_rust.rs    | 1 +
 rust/bindings/lib.rs           | 1 +
 rust/kernel/alloc/allocator.rs | 2 ++
 rust/kernel/error.rs           | 9 ++++++---
 rust/kernel/init.rs            | 5 +++++
 rust/kernel/init/__internal.rs | 2 ++
 rust/kernel/init/macros.rs     | 9 +++++++++
 rust/kernel/list.rs            | 1 +
 rust/kernel/print.rs           | 2 ++
 rust/kernel/str.rs             | 7 ++++---
 rust/kernel/sync/condvar.rs    | 2 +-
 rust/kernel/sync/lock.rs       | 6 +++---
 rust/kernel/types.rs           | 4 ++++
 rust/kernel/workqueue.rs       | 4 ++++
 rust/uapi/lib.rs               | 1 +
 16 files changed, 47 insertions(+), 10 deletions(-)

(limited to 'rust/kernel/types.rs')

diff --git a/Makefile b/Makefile
index 8e99f4a7e406..9730b4c3f029 100644
--- a/Makefile
+++ b/Makefile
@@ -457,6 +457,7 @@ export rust_common_flags := --edition=2021 \
 			    -Wclippy::needless_bitwise_bool \
 			    -Wclippy::needless_continue \
 			    -Wclippy::no_mangle_with_rust_abi \
+			    -Wclippy::undocumented_unsafe_blocks \
 			    -Wrustdoc::missing_crate_level_docs
 
 KBUILD_HOSTCFLAGS   := $(KBUILD_USERHOSTCFLAGS) $(HOST_LFS_CFLAGS) \
diff --git a/mm/kasan/kasan_test_rust.rs b/mm/kasan/kasan_test_rust.rs
index caa7175964ef..47bcf033dd4f 100644
--- a/mm/kasan/kasan_test_rust.rs
+++ b/mm/kasan/kasan_test_rust.rs
@@ -17,5 +17,6 @@ pub extern "C" fn kasan_test_rust_uaf() -> u8 {
     }
     let ptr: *mut u8 = addr_of_mut!(v[2048]);
     drop(v);
+    // SAFETY: Incorrect, on purpose.
     unsafe { *ptr }
 }
diff --git a/rust/bindings/lib.rs b/rust/bindings/lib.rs
index 93a1a3fc97bc..d6da3011281a 100644
--- a/rust/bindings/lib.rs
+++ b/rust/bindings/lib.rs
@@ -25,6 +25,7 @@
 )]
 
 #[allow(dead_code)]
+#[allow(clippy::undocumented_unsafe_blocks)]
 mod bindings_raw {
     // Use glob import here to expose all helpers.
     // Symbols defined within the module will take precedence to the glob import.
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index e6ea601f38c6..91216b36af69 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -31,6 +31,7 @@ pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: F
     unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 }
 }
 
+// SAFETY: TODO.
 unsafe impl GlobalAlloc for KernelAllocator {
     unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
         // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety
@@ -39,6 +40,7 @@ unsafe impl GlobalAlloc for KernelAllocator {
     }
 
     unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) {
+        // SAFETY: TODO.
         unsafe {
             bindings::kfree(ptr as *const core::ffi::c_void);
         }
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 6f1587a2524e..639bc7572f90 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -171,9 +171,11 @@ impl fmt::Debug for Error {
         match self.name() {
             // Print out number if no name can be found.
             None => f.debug_tuple("Error").field(&-self.0).finish(),
-            // SAFETY: These strings are ASCII-only.
             Some(name) => f
-                .debug_tuple(unsafe { core::str::from_utf8_unchecked(name) })
+                .debug_tuple(
+                    // SAFETY: These strings are ASCII-only.
+                    unsafe { core::str::from_utf8_unchecked(name) },
+                )
                 .finish(),
         }
     }
@@ -277,6 +279,8 @@ pub(crate) fn from_err_ptr<T>(ptr: *mut T) -> Result<*mut T> {
     if unsafe { bindings::IS_ERR(const_ptr) } {
         // SAFETY: The FFI function does not deref the pointer.
         let err = unsafe { bindings::PTR_ERR(const_ptr) };
+
+        #[allow(clippy::unnecessary_cast)]
         // CAST: If `IS_ERR()` returns `true`,
         // then `PTR_ERR()` is guaranteed to return a
         // negative value greater-or-equal to `-bindings::MAX_ERRNO`,
@@ -286,7 +290,6 @@ pub(crate) fn from_err_ptr<T>(ptr: *mut T) -> Result<*mut T> {
         //
         // SAFETY: `IS_ERR()` ensures `err` is a
         // negative value greater-or-equal to `-bindings::MAX_ERRNO`.
-        #[allow(clippy::unnecessary_cast)]
         return Err(unsafe { Error::from_errno_unchecked(err as core::ffi::c_int) });
     }
     Ok(ptr)
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index a17ac8762d8f..08b9d695c285 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -541,6 +541,7 @@ macro_rules! stack_try_pin_init {
 /// }
 /// pin_init!(&this in Buf {
 ///     buf: [0; 64],
+///     // SAFETY: TODO.
 ///     ptr: unsafe { addr_of_mut!((*this.as_ptr()).buf).cast() },
 ///     pin: PhantomPinned,
 /// });
@@ -875,6 +876,7 @@ pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
     /// }
     ///
     /// let foo = pin_init!(Foo {
+    ///     // SAFETY: TODO.
     ///     raw <- unsafe {
     ///         Opaque::ffi_init(|s| {
     ///             init_foo(s);
@@ -1162,6 +1164,7 @@ where
 // SAFETY: Every type can be initialized by-value.
 unsafe impl<T, E> Init<T, E> for T {
     unsafe fn __init(self, slot: *mut T) -> Result<(), E> {
+        // SAFETY: TODO.
         unsafe { slot.write(self) };
         Ok(())
     }
@@ -1170,6 +1173,7 @@ unsafe impl<T, E> Init<T, E> for T {
 // SAFETY: Every type can be initialized by-value. `__pinned_init` calls `__init`.
 unsafe impl<T, E> PinInit<T, E> for T {
     unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> {
+        // SAFETY: TODO.
         unsafe { self.__init(slot) }
     }
 }
@@ -1411,6 +1415,7 @@ pub fn zeroed<T: Zeroable>() -> impl Init<T> {
 
 macro_rules! impl_zeroable {
     ($($({$($generics:tt)*})? $t:ty, )*) => {
+        // SAFETY: Safety comments written in the macro invocation.
         $(unsafe impl$($($generics)*)? Zeroable for $t {})*
     };
 }
diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs
index 13cefd37512f..29f4fd00df3d 100644
--- a/rust/kernel/init/__internal.rs
+++ b/rust/kernel/init/__internal.rs
@@ -112,10 +112,12 @@ impl<T: ?Sized> Clone for AllData<T> {
 
 impl<T: ?Sized> Copy for AllData<T> {}
 
+// SAFETY: TODO.
 unsafe impl<T: ?Sized> InitData for AllData<T> {
     type Datee = T;
 }
 
+// SAFETY: TODO.
 unsafe impl<T: ?Sized> HasInitData for T {
     type InitData = AllData<T>;
 
diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs
index 9a0c4650ef67..736fe0ce0cd9 100644
--- a/rust/kernel/init/macros.rs
+++ b/rust/kernel/init/macros.rs
@@ -513,6 +513,7 @@ macro_rules! __pinned_drop {
             }
         ),
     ) => {
+        // SAFETY: TODO.
         unsafe $($impl_sig)* {
             // Inherit all attributes and the type/ident tokens for the signature.
             $(#[$($attr)*])*
@@ -872,6 +873,7 @@ macro_rules! __pin_data {
                 }
             }
 
+            // SAFETY: TODO.
             unsafe impl<$($impl_generics)*>
                 $crate::init::__internal::PinData for __ThePinData<$($ty_generics)*>
             where $($whr)*
@@ -997,6 +999,7 @@ macro_rules! __pin_data {
                     slot: *mut $p_type,
                     init: impl $crate::init::PinInit<$p_type, E>,
                 ) -> ::core::result::Result<(), E> {
+                    // SAFETY: TODO.
                     unsafe { $crate::init::PinInit::__pinned_init(init, slot) }
                 }
             )*
@@ -1007,6 +1010,7 @@ macro_rules! __pin_data {
                     slot: *mut $type,
                     init: impl $crate::init::Init<$type, E>,
                 ) -> ::core::result::Result<(), E> {
+                    // SAFETY: TODO.
                     unsafe { $crate::init::Init::__init(init, slot) }
                 }
             )*
@@ -1121,6 +1125,8 @@ macro_rules! __init_internal {
         // no possibility of returning without `unsafe`.
         struct __InitOk;
         // Get the data about fields from the supplied type.
+        //
+        // SAFETY: TODO.
         let data = unsafe {
             use $crate::init::__internal::$has_data;
             // Here we abuse `paste!` to retokenize `$t`. Declarative macros have some internal
@@ -1176,6 +1182,7 @@ macro_rules! __init_internal {
         let init = move |slot| -> ::core::result::Result<(), $err> {
             init(slot).map(|__InitOk| ())
         };
+        // SAFETY: TODO.
         let init = unsafe { $crate::init::$construct_closure::<_, $err>(init) };
         init
     }};
@@ -1324,6 +1331,8 @@ macro_rules! __init_internal {
         // Endpoint, nothing more to munch, create the initializer.
         // Since we are in the closure that is never called, this will never get executed.
         // We abuse `slot` to get the correct type inference here:
+        //
+        // SAFETY: TODO.
         unsafe {
             // Here we abuse `paste!` to retokenize `$t`. Declarative macros have some internal
             // information that is associated to already parsed fragments, so a path fragment
diff --git a/rust/kernel/list.rs b/rust/kernel/list.rs
index 5b4aec29eb67..fb93330f4af4 100644
--- a/rust/kernel/list.rs
+++ b/rust/kernel/list.rs
@@ -354,6 +354,7 @@ impl<T: ?Sized + ListItem<ID>, const ID: u64> List<T, ID> {
     ///
     /// `item` must not be in a different linked list (with the same id).
     pub unsafe fn remove(&mut self, item: &T) -> Option<ListArc<T, ID>> {
+        // SAFETY: TODO.
         let mut item = unsafe { ListLinks::fields(T::view_links(item)) };
         // SAFETY: The user provided a reference, and reference are never dangling.
         //
diff --git a/rust/kernel/print.rs b/rust/kernel/print.rs
index 508b0221256c..fe53fc469c4f 100644
--- a/rust/kernel/print.rs
+++ b/rust/kernel/print.rs
@@ -23,6 +23,7 @@ unsafe extern "C" fn rust_fmt_argument(
     use fmt::Write;
     // SAFETY: The C contract guarantees that `buf` is valid if it's less than `end`.
     let mut w = unsafe { RawFormatter::from_ptrs(buf.cast(), end.cast()) };
+    // SAFETY: TODO.
     let _ = w.write_fmt(unsafe { *(ptr as *const fmt::Arguments<'_>) });
     w.pos().cast()
 }
@@ -102,6 +103,7 @@ pub unsafe fn call_printk(
 ) {
     // `_printk` does not seem to fail in any path.
     #[cfg(CONFIG_PRINTK)]
+    // SAFETY: TODO.
     unsafe {
         bindings::_printk(
             format_string.as_ptr() as _,
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index bb8d4f41475b..66d4527f6c6f 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -162,10 +162,10 @@ impl CStr {
     /// Returns the length of this string with `NUL`.
     #[inline]
     pub const fn len_with_nul(&self) -> usize {
-        // SAFETY: This is one of the invariant of `CStr`.
-        // We add a `unreachable_unchecked` here to hint the optimizer that
-        // the value returned from this function is non-zero.
         if self.0.is_empty() {
+            // SAFETY: This is one of the invariant of `CStr`.
+            // We add a `unreachable_unchecked` here to hint the optimizer that
+            // the value returned from this function is non-zero.
             unsafe { core::hint::unreachable_unchecked() };
         }
         self.0.len()
@@ -301,6 +301,7 @@ impl CStr {
     /// ```
     #[inline]
     pub unsafe fn as_str_unchecked(&self) -> &str {
+        // SAFETY: TODO.
         unsafe { core::str::from_utf8_unchecked(self.as_bytes()) }
     }
 
diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs
index 2b306afbe56d..7e00048bf4b1 100644
--- a/rust/kernel/sync/condvar.rs
+++ b/rust/kernel/sync/condvar.rs
@@ -92,8 +92,8 @@ pub struct CondVar {
     _pin: PhantomPinned,
 }
 
-// SAFETY: `CondVar` only uses a `struct wait_queue_head`, which is safe to use on any thread.
 #[allow(clippy::non_send_fields_in_send_ty)]
+// SAFETY: `CondVar` only uses a `struct wait_queue_head`, which is safe to use on any thread.
 unsafe impl Send for CondVar {}
 
 // SAFETY: `CondVar` only uses a `struct wait_queue_head`, which is safe to use on multiple threads
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index f6c34ca4d819..07fcf2d8efc6 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -150,9 +150,9 @@ impl<T: ?Sized, B: Backend> Guard<'_, T, B> {
         // SAFETY: The caller owns the lock, so it is safe to unlock it.
         unsafe { B::unlock(self.lock.state.get(), &self.state) };
 
-        // SAFETY: The lock was just unlocked above and is being relocked now.
-        let _relock =
-            ScopeGuard::new(|| unsafe { B::relock(self.lock.state.get(), &mut self.state) });
+        let _relock = ScopeGuard::new(||
+                // SAFETY: The lock was just unlocked above and is being relocked now.
+                unsafe { B::relock(self.lock.state.get(), &mut self.state) });
 
         cb()
     }
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index e00c14687eba..fd8e2b6039e0 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -410,6 +410,7 @@ impl<T: AlwaysRefCounted> ARef<T> {
     ///
     /// struct Empty {}
     ///
+    /// # // SAFETY: TODO.
     /// unsafe impl AlwaysRefCounted for Empty {
     ///     fn inc_ref(&self) {}
     ///     unsafe fn dec_ref(_obj: NonNull<Self>) {}
@@ -417,6 +418,7 @@ impl<T: AlwaysRefCounted> ARef<T> {
     ///
     /// let mut data = Empty {};
     /// let ptr = NonNull::<Empty>::new(&mut data as *mut _).unwrap();
+    /// # // SAFETY: TODO.
     /// let data_ref: ARef<Empty> = unsafe { ARef::from_raw(ptr) };
     /// let raw_ptr: NonNull<Empty> = ARef::into_raw(data_ref);
     ///
@@ -492,6 +494,7 @@ pub unsafe trait FromBytes {}
 
 macro_rules! impl_frombytes {
     ($($({$($generics:tt)*})? $t:ty, )*) => {
+        // SAFETY: Safety comments written in the macro invocation.
         $(unsafe impl$($($generics)*)? FromBytes for $t {})*
     };
 }
@@ -526,6 +529,7 @@ pub unsafe trait AsBytes {}
 
 macro_rules! impl_asbytes {
     ($($({$($generics:tt)*})? $t:ty, )*) => {
+        // SAFETY: Safety comments written in the macro invocation.
         $(unsafe impl$($($generics)*)? AsBytes for $t {})*
     };
 }
diff --git a/rust/kernel/workqueue.rs b/rust/kernel/workqueue.rs
index 493288dc1de0..3b3f1dbe8192 100644
--- a/rust/kernel/workqueue.rs
+++ b/rust/kernel/workqueue.rs
@@ -519,6 +519,7 @@ impl_has_work! {
     impl{T} HasWork<Self> for ClosureWork<T> { self.work }
 }
 
+// SAFETY: TODO.
 unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Arc<T>
 where
     T: WorkItem<ID, Pointer = Self>,
@@ -536,6 +537,7 @@ where
     }
 }
 
+// SAFETY: TODO.
 unsafe impl<T, const ID: u64> RawWorkItem<ID> for Arc<T>
 where
     T: WorkItem<ID, Pointer = Self>,
@@ -564,6 +566,7 @@ where
     }
 }
 
+// SAFETY: TODO.
 unsafe impl<T, const ID: u64> WorkItemPointer<ID> for Pin<Box<T>>
 where
     T: WorkItem<ID, Pointer = Self>,
@@ -583,6 +586,7 @@ where
     }
 }
 
+// SAFETY: TODO.
 unsafe impl<T, const ID: u64> RawWorkItem<ID> for Pin<Box<T>>
 where
     T: WorkItem<ID, Pointer = Self>,
diff --git a/rust/uapi/lib.rs b/rust/uapi/lib.rs
index 80a00260e3e7..fea2de330d19 100644
--- a/rust/uapi/lib.rs
+++ b/rust/uapi/lib.rs
@@ -14,6 +14,7 @@
 #![cfg_attr(test, allow(unsafe_op_in_unsafe_fn))]
 #![allow(
     clippy::all,
+    clippy::undocumented_unsafe_blocks,
     dead_code,
     missing_docs,
     non_camel_case_types,
-- 
cgit v1.2.3


From 3fcc23397628c2357dbe66df59644e09f72ac725 Mon Sep 17 00:00:00 2001
From: Miguel Ojeda <ojeda@kernel.org>
Date: Wed, 4 Sep 2024 22:43:35 +0200
Subject: rust: enable `clippy::ignored_unit_patterns` lint

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 <aliceryhl@google.com>
Reviewed-by: Trevor Gross <tmgross@umich.edu>
Tested-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/r/20240904204347.168520-8-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 Makefile             | 1 +
 rust/kernel/types.rs | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

(limited to 'rust/kernel/types.rs')

diff --git a/Makefile b/Makefile
index 3476afc70788..b0696cd0599c 100644
--- a/Makefile
+++ b/Makefile
@@ -453,6 +453,7 @@ export rust_common_flags := --edition=2021 \
 			    -Wunreachable_pub \
 			    -Wclippy::all \
 			    -Wclippy::dbg_macro \
+			    -Wclippy::ignored_unit_patterns \
 			    -Wclippy::mut_mut \
 			    -Wclippy::needless_bitwise_bool \
 			    -Wclippy::needless_continue \
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index fd8e2b6039e0..28d9e5ea3df4 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -225,7 +225,7 @@ impl<T, F: FnOnce(T)> ScopeGuard<T, F> {
 impl ScopeGuard<(), fn(())> {
     /// Creates a new guarded object with the given cleanup function.
     pub fn new(cleanup: impl FnOnce()) -> ScopeGuard<(), impl FnOnce(())> {
-        ScopeGuard::new_with_data((), move |_| cleanup())
+        ScopeGuard::new_with_data((), move |()| cleanup())
     }
 }
 
-- 
cgit v1.2.3


From ce1c54fdff7c4556b08f5b875a331d8952e8b6b7 Mon Sep 17 00:00:00 2001
From: Aliet Exposito Garcia <aliet.exposito@gmail.com>
Date: Wed, 18 Sep 2024 18:51:14 -0400
Subject: rust: kernel: move `FromBytes` and `AsBytes` traits to a new
 `transmute` module

Refactor the `FromBytes` and `AsBytes` traits from `types.rs` into a new
`transmute.rs` module:

 - Add `rust/kernel/transmute.rs` with the definitions of `FromBytes`
   and `AsBytes`.

 - Remove the same trait definitions from `rust/kernel/types.rs`.

 - Update `rust/kernel/uaccess.rs` to import `AsBytes` and `FromBytes`
   from `transmute.rs`.

The traits and their implementations remain unchanged.

Suggested-by: Benno Lossin <benno.lossin@proton.me>
Link: https://github.com/Rust-for-Linux/linux/issues/1117
Signed-off-by: Aliet Exposito Garcia <aliet.exposito@gmail.com>
Reviewed-by: Fiona Behrens <me@kloenk.dev>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/r/20240918225115.2309224-2-aliet.exposito@gmail.com
[ Rebased on top of the lints series and slightly reworded. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/lib.rs       |  1 +
 rust/kernel/transmute.rs | 71 ++++++++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/types.rs     | 68 ----------------------------------------------
 rust/kernel/uaccess.rs   |  2 +-
 4 files changed, 73 insertions(+), 69 deletions(-)
 create mode 100644 rust/kernel/transmute.rs

(limited to 'rust/kernel/types.rs')

diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 3e4bd6e57bee..dc37aef6a008 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -54,6 +54,7 @@ pub mod str;
 pub mod sync;
 pub mod task;
 pub mod time;
+pub mod transmute;
 pub mod types;
 pub mod uaccess;
 pub mod workqueue;
diff --git a/rust/kernel/transmute.rs b/rust/kernel/transmute.rs
new file mode 100644
index 000000000000..1c7d43771a37
--- /dev/null
+++ b/rust/kernel/transmute.rs
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Traits for transmuting types.
+
+/// Types for which any bit pattern is valid.
+///
+/// Not all types are valid for all values. For example, a `bool` must be either zero or one, so
+/// reading arbitrary bytes into something that contains a `bool` is not okay.
+///
+/// It's okay for the type to have padding, as initializing those bytes has no effect.
+///
+/// # Safety
+///
+/// All bit-patterns must be valid for this type. This type must not have interior mutability.
+pub unsafe trait FromBytes {}
+
+macro_rules! impl_frombytes {
+    ($($({$($generics:tt)*})? $t:ty, )*) => {
+        // SAFETY: Safety comments written in the macro invocation.
+        $(unsafe impl$($($generics)*)? FromBytes for $t {})*
+    };
+}
+
+impl_frombytes! {
+    // SAFETY: All bit patterns are acceptable values of the types below.
+    u8, u16, u32, u64, usize,
+    i8, i16, i32, i64, isize,
+
+    // SAFETY: If all bit patterns are acceptable for individual values in an array, then all bit
+    // patterns are also acceptable for arrays of that type.
+    {<T: FromBytes>} [T],
+    {<T: FromBytes, const N: usize>} [T; N],
+}
+
+/// Types that can be viewed as an immutable slice of initialized bytes.
+///
+/// If a struct implements this trait, then it is okay to copy it byte-for-byte to userspace. This
+/// means that it should not have any padding, as padding bytes are uninitialized. Reading
+/// uninitialized memory is not just undefined behavior, it may even lead to leaking sensitive
+/// information on the stack to userspace.
+///
+/// The struct should also not hold kernel pointers, as kernel pointer addresses are also considered
+/// sensitive. However, leaking kernel pointers is not considered undefined behavior by Rust, so
+/// this is a correctness requirement, but not a safety requirement.
+///
+/// # Safety
+///
+/// Values of this type may not contain any uninitialized bytes. This type must not have interior
+/// mutability.
+pub unsafe trait AsBytes {}
+
+macro_rules! impl_asbytes {
+    ($($({$($generics:tt)*})? $t:ty, )*) => {
+        // SAFETY: Safety comments written in the macro invocation.
+        $(unsafe impl$($($generics)*)? AsBytes for $t {})*
+    };
+}
+
+impl_asbytes! {
+    // SAFETY: Instances of the following types have no uninitialized portions.
+    u8, u16, u32, u64, usize,
+    i8, i16, i32, i64, isize,
+    bool,
+    char,
+    str,
+
+    // SAFETY: If individual values in an array have no uninitialized portions, then the array
+    // itself does not have any uninitialized portions either.
+    {<T: AsBytes>} [T],
+    {<T: AsBytes, const N: usize>} [T; N],
+}
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 28d9e5ea3df4..085e8076f078 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -479,71 +479,3 @@ pub enum Either<L, R> {
     /// Constructs an instance of [`Either`] containing a value of type `R`.
     Right(R),
 }
-
-/// Types for which any bit pattern is valid.
-///
-/// Not all types are valid for all values. For example, a `bool` must be either zero or one, so
-/// reading arbitrary bytes into something that contains a `bool` is not okay.
-///
-/// It's okay for the type to have padding, as initializing those bytes has no effect.
-///
-/// # Safety
-///
-/// All bit-patterns must be valid for this type. This type must not have interior mutability.
-pub unsafe trait FromBytes {}
-
-macro_rules! impl_frombytes {
-    ($($({$($generics:tt)*})? $t:ty, )*) => {
-        // SAFETY: Safety comments written in the macro invocation.
-        $(unsafe impl$($($generics)*)? FromBytes for $t {})*
-    };
-}
-
-impl_frombytes! {
-    // SAFETY: All bit patterns are acceptable values of the types below.
-    u8, u16, u32, u64, usize,
-    i8, i16, i32, i64, isize,
-
-    // SAFETY: If all bit patterns are acceptable for individual values in an array, then all bit
-    // patterns are also acceptable for arrays of that type.
-    {<T: FromBytes>} [T],
-    {<T: FromBytes, const N: usize>} [T; N],
-}
-
-/// Types that can be viewed as an immutable slice of initialized bytes.
-///
-/// If a struct implements this trait, then it is okay to copy it byte-for-byte to userspace. This
-/// means that it should not have any padding, as padding bytes are uninitialized. Reading
-/// uninitialized memory is not just undefined behavior, it may even lead to leaking sensitive
-/// information on the stack to userspace.
-///
-/// The struct should also not hold kernel pointers, as kernel pointer addresses are also considered
-/// sensitive. However, leaking kernel pointers is not considered undefined behavior by Rust, so
-/// this is a correctness requirement, but not a safety requirement.
-///
-/// # Safety
-///
-/// Values of this type may not contain any uninitialized bytes. This type must not have interior
-/// mutability.
-pub unsafe trait AsBytes {}
-
-macro_rules! impl_asbytes {
-    ($($({$($generics:tt)*})? $t:ty, )*) => {
-        // SAFETY: Safety comments written in the macro invocation.
-        $(unsafe impl$($($generics)*)? AsBytes for $t {})*
-    };
-}
-
-impl_asbytes! {
-    // SAFETY: Instances of the following types have no uninitialized portions.
-    u8, u16, u32, u64, usize,
-    i8, i16, i32, i64, isize,
-    bool,
-    char,
-    str,
-
-    // SAFETY: If individual values in an array have no uninitialized portions, then the array
-    // itself does not have any uninitialized portions either.
-    {<T: AsBytes>} [T],
-    {<T: AsBytes, const N: usize>} [T; N],
-}
diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs
index e9347cff99ab..0af243482eac 100644
--- a/rust/kernel/uaccess.rs
+++ b/rust/kernel/uaccess.rs
@@ -9,7 +9,7 @@ use crate::{
     bindings,
     error::Result,
     prelude::*,
-    types::{AsBytes, FromBytes},
+    transmute::{AsBytes, FromBytes},
 };
 use alloc::vec::Vec;
 use core::ffi::{c_ulong, c_void};
-- 
cgit v1.2.3


From e8c6ccdbcaaf31f26c0fffd4073edd0b0147cdc6 Mon Sep 17 00:00:00 2001
From: Danilo Krummrich <dakr@kernel.org>
Date: Fri, 4 Oct 2024 17:41:17 +0200
Subject: rust: alloc: remove extension of std's `Box`

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 <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241004154149.93856-14-dakr@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/alloc.rs         |  1 -
 rust/kernel/alloc/box_ext.rs | 89 --------------------------------------------
 rust/kernel/init.rs          | 46 +----------------------
 rust/kernel/lib.rs           |  1 -
 rust/kernel/prelude.rs       |  4 +-
 rust/kernel/types.rs         | 50 -------------------------
 6 files changed, 3 insertions(+), 188 deletions(-)
 delete mode 100644 rust/kernel/alloc/box_ext.rs

(limited to 'rust/kernel/types.rs')

diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index 3628e16240a6..94f4de5e0cdc 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -4,7 +4,6 @@
 
 #[cfg(not(any(test, testlib)))]
 pub mod allocator;
-pub mod box_ext;
 pub mod kbox;
 pub mod vec_ext;
 
diff --git a/rust/kernel/alloc/box_ext.rs b/rust/kernel/alloc/box_ext.rs
deleted file mode 100644
index 7009ad78d4e0..000000000000
--- a/rust/kernel/alloc/box_ext.rs
+++ /dev/null
@@ -1,89 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-
-//! Extensions to [`Box`] for fallible allocations.
-
-use super::{AllocError, Flags};
-use alloc::boxed::Box;
-use core::{mem::MaybeUninit, ptr, result::Result};
-
-/// Extensions to [`Box`].
-pub trait BoxExt<T>: Sized {
-    /// Allocates a new box.
-    ///
-    /// The allocation may fail, in which case an error is returned.
-    fn new(x: T, flags: Flags) -> Result<Self, AllocError>;
-
-    /// Allocates a new uninitialised box.
-    ///
-    /// The allocation may fail, in which case an error is returned.
-    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError>;
-
-    /// Drops the contents, but keeps the allocation.
-    ///
-    /// # Examples
-    ///
-    /// ```
-    /// use kernel::alloc::{flags, box_ext::BoxExt};
-    /// let value = Box::new([0; 32], flags::GFP_KERNEL)?;
-    /// assert_eq!(*value, [0; 32]);
-    /// let mut value = Box::drop_contents(value);
-    /// // Now we can re-use `value`:
-    /// value.write([1; 32]);
-    /// // SAFETY: We just wrote to it.
-    /// let value = unsafe { value.assume_init() };
-    /// assert_eq!(*value, [1; 32]);
-    /// # Ok::<(), Error>(())
-    /// ```
-    fn drop_contents(this: Self) -> Box<MaybeUninit<T>>;
-}
-
-impl<T> BoxExt<T> for Box<T> {
-    fn new(x: T, flags: Flags) -> Result<Self, AllocError> {
-        let mut b = <Self as BoxExt<_>>::new_uninit(flags)?;
-        b.write(x);
-        // SAFETY: We just wrote to it.
-        Ok(unsafe { b.assume_init() })
-    }
-
-    #[cfg(any(test, testlib))]
-    fn new_uninit(_flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
-        Ok(Box::new_uninit())
-    }
-
-    #[cfg(not(any(test, testlib)))]
-    fn new_uninit(flags: Flags) -> Result<Box<MaybeUninit<T>>, AllocError> {
-        let ptr = if core::mem::size_of::<MaybeUninit<T>>() == 0 {
-            core::ptr::NonNull::<_>::dangling().as_ptr()
-        } else {
-            let layout = core::alloc::Layout::new::<MaybeUninit<T>>();
-
-            // SAFETY: Memory is being allocated (first arg is null). The only other source of
-            // safety issues is sleeping on atomic context, which is addressed by klint. Lastly,
-            // the type is not a SZT (checked above).
-            let ptr =
-                unsafe { super::allocator::krealloc_aligned(core::ptr::null_mut(), layout, flags) };
-            if ptr.is_null() {
-                return Err(AllocError);
-            }
-
-            ptr.cast::<MaybeUninit<T>>()
-        };
-
-        // SAFETY: For non-zero-sized types, we allocate above using the global allocator. For
-        // zero-sized types, we use `NonNull::dangling`.
-        Ok(unsafe { Box::from_raw(ptr) })
-    }
-
-    fn drop_contents(this: Self) -> Box<MaybeUninit<T>> {
-        let ptr = Box::into_raw(this);
-        // SAFETY: `ptr` is valid, because it came from `Box::into_raw`.
-        unsafe { ptr::drop_in_place(ptr) };
-
-        // CAST: `MaybeUninit<T>` is a transparent wrapper of `T`.
-        let ptr = ptr.cast::<MaybeUninit<T>>();
-
-        // SAFETY: `ptr` is valid for writes, because it came from `Box::into_raw` and it is valid for
-        // reads, since the pointer came from `Box::into_raw` and the type is `MaybeUninit<T>`.
-        unsafe { Box::from_raw(ptr) }
-    }
-}
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index c889f2640b56..c9919ba0b683 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -211,13 +211,12 @@
 //! [`pin_init!`]: crate::pin_init!
 
 use crate::{
-    alloc::{box_ext::BoxExt, AllocError, Flags, KBox},
+    alloc::{AllocError, Flags, KBox},
     error::{self, Error},
     sync::Arc,
     sync::UniqueArc,
     types::{Opaque, ScopeGuard},
 };
-use alloc::boxed::Box;
 use core::{
     cell::UnsafeCell,
     convert::Infallible,
@@ -588,7 +587,6 @@ macro_rules! pin_init {
 /// # Examples
 ///
 /// ```rust
-/// # #![feature(new_uninit)]
 /// use kernel::{init::{self, PinInit}, error::Error};
 /// #[pin_data]
 /// struct BigBuf {
@@ -1245,26 +1243,6 @@ impl<T> InPlaceInit<T> for Arc<T> {
     }
 }
 
-impl<T> InPlaceInit<T> for Box<T> {
-    type PinnedSelf = Pin<Self>;
-
-    #[inline]
-    fn try_pin_init<E>(init: impl PinInit<T, E>, flags: Flags) -> Result<Self::PinnedSelf, E>
-    where
-        E: From<AllocError>,
-    {
-        <Box<_> as BoxExt<_>>::new_uninit(flags)?.write_pin_init(init)
-    }
-
-    #[inline]
-    fn try_init<E>(init: impl Init<T, E>, flags: Flags) -> Result<Self, E>
-    where
-        E: From<AllocError>,
-    {
-        <Box<_> as BoxExt<_>>::new_uninit(flags)?.write_init(init)
-    }
-}
-
 impl<T> InPlaceInit<T> for UniqueArc<T> {
     type PinnedSelf = Pin<Self>;
 
@@ -1301,28 +1279,6 @@ pub trait InPlaceWrite<T> {
     fn write_pin_init<E>(self, init: impl PinInit<T, E>) -> Result<Pin<Self::Initialized>, E>;
 }
 
-impl<T> InPlaceWrite<T> for Box<MaybeUninit<T>> {
-    type Initialized = Box<T>;
-
-    fn write_init<E>(mut self, init: impl Init<T, E>) -> Result<Self::Initialized, E> {
-        let slot = self.as_mut_ptr();
-        // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
-        // slot is valid.
-        unsafe { init.__init(slot)? };
-        // SAFETY: All fields have been initialized.
-        Ok(unsafe { self.assume_init() })
-    }
-
-    fn write_pin_init<E>(mut self, init: impl PinInit<T, E>) -> Result<Pin<Self::Initialized>, E> {
-        let slot = self.as_mut_ptr();
-        // SAFETY: When init errors/panics, slot will get deallocated but not dropped,
-        // slot is valid and will not be moved, because we pin it later.
-        unsafe { init.__pinned_init(slot)? };
-        // SAFETY: All fields have been initialized.
-        Ok(unsafe { self.assume_init() }.into())
-    }
-}
-
 impl<T> InPlaceWrite<T> for UniqueArc<MaybeUninit<T>> {
     type Initialized = UniqueArc<T>;
 
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index dc37aef6a008..34e9151db58d 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -16,7 +16,6 @@
 #![feature(coerce_unsized)]
 #![feature(dispatch_from_dyn)]
 #![feature(lint_reasons)]
-#![feature(new_uninit)]
 #![feature(unsize)]
 
 // Ensure conditional compilation based on the kernel configuration works;
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index a9210634a8c3..c1f8e5c832e2 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -14,10 +14,10 @@
 #[doc(no_inline)]
 pub use core::pin::Pin;
 
-pub use crate::alloc::{box_ext::BoxExt, flags::*, vec_ext::VecExt, KBox, KVBox, VBox};
+pub use crate::alloc::{flags::*, vec_ext::VecExt, KBox, KVBox, VBox};
 
 #[doc(no_inline)]
-pub use alloc::{boxed::Box, vec::Vec};
+pub use alloc::vec::Vec;
 
 #[doc(no_inline)]
 pub use macros::{module, pin_data, pinned_drop, vtable, Zeroable};
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 085e8076f078..34f1b31753df 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -3,13 +3,11 @@
 //! Kernel types.
 
 use crate::init::{self, PinInit};
-use alloc::boxed::Box;
 use core::{
     cell::UnsafeCell,
     marker::{PhantomData, PhantomPinned},
     mem::{ManuallyDrop, MaybeUninit},
     ops::{Deref, DerefMut},
-    pin::Pin,
     ptr::NonNull,
 };
 
@@ -71,54 +69,6 @@ pub trait ForeignOwnable: Sized {
     }
 }
 
-impl<T: 'static> ForeignOwnable for Box<T> {
-    type Borrowed<'a> = &'a T;
-
-    fn into_foreign(self) -> *const core::ffi::c_void {
-        Box::into_raw(self) as _
-    }
-
-    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
-        // SAFETY: The safety requirements for this function ensure that the object is still alive,
-        // so it is safe to dereference the raw pointer.
-        // The safety requirements of `from_foreign` also ensure that the object remains alive for
-        // the lifetime of the returned value.
-        unsafe { &*ptr.cast() }
-    }
-
-    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
-        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
-        // call to `Self::into_foreign`.
-        unsafe { Box::from_raw(ptr as _) }
-    }
-}
-
-impl<T: 'static> ForeignOwnable for Pin<Box<T>> {
-    type Borrowed<'a> = Pin<&'a T>;
-
-    fn into_foreign(self) -> *const core::ffi::c_void {
-        // SAFETY: We are still treating the box as pinned.
-        Box::into_raw(unsafe { Pin::into_inner_unchecked(self) }) as _
-    }
-
-    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> Pin<&'a T> {
-        // SAFETY: The safety requirements for this function ensure that the object is still alive,
-        // so it is safe to dereference the raw pointer.
-        // The safety requirements of `from_foreign` also ensure that the object remains alive for
-        // the lifetime of the returned value.
-        let r = unsafe { &*ptr.cast() };
-
-        // SAFETY: This pointer originates from a `Pin<Box<T>>`.
-        unsafe { Pin::new_unchecked(r) }
-    }
-
-    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
-        // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
-        // call to `Self::into_foreign`.
-        unsafe { Pin::new_unchecked(Box::from_raw(ptr as _)) }
-    }
-}
-
 impl ForeignOwnable for () {
     type Borrowed<'a> = ();
 
-- 
cgit v1.2.3


From 58eff8e872bd04ccb3adcf99aec7334ffad06cfd Mon Sep 17 00:00:00 2001
From: Danilo Krummrich <dakr@kernel.org>
Date: Fri, 4 Oct 2024 17:41:23 +0200
Subject: rust: treewide: switch to the kernel `Vec` type

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

Reviewed-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Benno Lossin <benno.lossin@proton.me>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
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 <ojeda@kernel.org>
---
 mm/kasan/kasan_test_rust.rs   |  2 +-
 rust/kernel/str.rs            | 12 +++++-------
 rust/kernel/sync/locked_by.rs |  2 +-
 rust/kernel/types.rs          |  2 +-
 rust/kernel/uaccess.rs        | 17 +++++++----------
 rust/macros/lib.rs            |  6 +++---
 samples/rust/rust_minimal.rs  |  4 ++--
 7 files changed, 20 insertions(+), 25 deletions(-)

(limited to 'rust/kernel/types.rs')

diff --git a/mm/kasan/kasan_test_rust.rs b/mm/kasan/kasan_test_rust.rs
index 47bcf033dd4f..5b34edf30e72 100644
--- a/mm/kasan/kasan_test_rust.rs
+++ b/mm/kasan/kasan_test_rust.rs
@@ -11,7 +11,7 @@ use kernel::prelude::*;
 /// drop the vector, and touch it.
 #[no_mangle]
 pub extern "C" fn kasan_test_rust_uaf() -> u8 {
-    let mut v: Vec<u8> = Vec::new();
+    let mut v: KVec<u8> = KVec::new();
     for _ in 0..4096 {
         v.push(0x42, GFP_KERNEL).unwrap();
     }
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 66d4527f6c6f..6053bc7a98d1 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -2,8 +2,7 @@
 
 //! String representations.
 
-use crate::alloc::{flags::*, vec_ext::VecExt, AllocError};
-use alloc::vec::Vec;
+use crate::alloc::{flags::*, AllocError, KVec};
 use core::fmt::{self, Write};
 use core::ops::{self, Deref, DerefMut, Index};
 
@@ -791,7 +790,7 @@ impl fmt::Write for Formatter {
 /// assert_eq!(s.is_ok(), false);
 /// ```
 pub struct CString {
-    buf: Vec<u8>,
+    buf: KVec<u8>,
 }
 
 impl CString {
@@ -804,7 +803,7 @@ impl CString {
         let size = f.bytes_written();
 
         // Allocate a vector with the required number of bytes, and write to it.
-        let mut buf = <Vec<_> as VecExt<_>>::with_capacity(size, GFP_KERNEL)?;
+        let mut buf = KVec::with_capacity(size, GFP_KERNEL)?;
         // SAFETY: The buffer stored in `buf` is at least of size `size` and is valid for writes.
         let mut f = unsafe { Formatter::from_buffer(buf.as_mut_ptr(), size) };
         f.write_fmt(args)?;
@@ -851,10 +850,9 @@ impl<'a> TryFrom<&'a CStr> for CString {
     type Error = AllocError;
 
     fn try_from(cstr: &'a CStr) -> Result<CString, AllocError> {
-        let mut buf = Vec::new();
+        let mut buf = KVec::new();
 
-        <Vec<_> as VecExt<_>>::extend_from_slice(&mut buf, cstr.as_bytes_with_nul(), GFP_KERNEL)
-            .map_err(|_| AllocError)?;
+        buf.extend_from_slice(cstr.as_bytes_with_nul(), GFP_KERNEL)?;
 
         // INVARIANT: The `CStr` and `CString` types have the same invariants for
         // the string data, and we copied it over without changes.
diff --git a/rust/kernel/sync/locked_by.rs b/rust/kernel/sync/locked_by.rs
index ce2ee8d87865..a7b244675c2b 100644
--- a/rust/kernel/sync/locked_by.rs
+++ b/rust/kernel/sync/locked_by.rs
@@ -43,7 +43,7 @@ use core::{cell::UnsafeCell, mem::size_of, ptr};
 /// struct InnerDirectory {
 ///     /// The sum of the bytes used by all files.
 ///     bytes_used: u64,
-///     _files: Vec<File>,
+///     _files: KVec<File>,
 /// }
 ///
 /// struct Directory {
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index 34f1b31753df..ced143600eb1 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -135,7 +135,7 @@ impl ForeignOwnable for () {
 /// # use kernel::types::ScopeGuard;
 /// fn example3(arg: bool) -> Result {
 ///     let mut vec =
-///         ScopeGuard::new_with_data(Vec::new(), |v| pr_info!("vec had {} elements\n", v.len()));
+///         ScopeGuard::new_with_data(KVec::new(), |v| pr_info!("vec had {} elements\n", v.len()));
 ///
 ///     vec.push(10u8, GFP_KERNEL)?;
 ///     if arg {
diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs
index 0af243482eac..2c953ba53c77 100644
--- a/rust/kernel/uaccess.rs
+++ b/rust/kernel/uaccess.rs
@@ -11,7 +11,6 @@ use crate::{
     prelude::*,
     transmute::{AsBytes, FromBytes},
 };
-use alloc::vec::Vec;
 use core::ffi::{c_ulong, c_void};
 use core::mem::{size_of, MaybeUninit};
 
@@ -46,7 +45,6 @@ pub type UserPtr = usize;
 /// every byte in the region.
 ///
 /// ```no_run
-/// use alloc::vec::Vec;
 /// use core::ffi::c_void;
 /// use kernel::error::Result;
 /// use kernel::uaccess::{UserPtr, UserSlice};
@@ -54,7 +52,7 @@ pub type UserPtr = usize;
 /// fn bytes_add_one(uptr: UserPtr, len: usize) -> Result<()> {
 ///     let (read, mut write) = UserSlice::new(uptr, len).reader_writer();
 ///
-///     let mut buf = Vec::new();
+///     let mut buf = KVec::new();
 ///     read.read_all(&mut buf, GFP_KERNEL)?;
 ///
 ///     for b in &mut buf {
@@ -69,7 +67,6 @@ pub type UserPtr = usize;
 /// Example illustrating a TOCTOU (time-of-check to time-of-use) bug.
 ///
 /// ```no_run
-/// use alloc::vec::Vec;
 /// use core::ffi::c_void;
 /// use kernel::error::{code::EINVAL, Result};
 /// use kernel::uaccess::{UserPtr, UserSlice};
@@ -78,21 +75,21 @@ pub type UserPtr = usize;
 /// fn is_valid(uptr: UserPtr, len: usize) -> Result<bool> {
 ///     let read = UserSlice::new(uptr, len).reader();
 ///
-///     let mut buf = Vec::new();
+///     let mut buf = KVec::new();
 ///     read.read_all(&mut buf, GFP_KERNEL)?;
 ///
 ///     todo!()
 /// }
 ///
 /// /// Returns the bytes behind this user pointer if they are valid.
-/// fn get_bytes_if_valid(uptr: UserPtr, len: usize) -> Result<Vec<u8>> {
+/// fn get_bytes_if_valid(uptr: UserPtr, len: usize) -> Result<KVec<u8>> {
 ///     if !is_valid(uptr, len)? {
 ///         return Err(EINVAL);
 ///     }
 ///
 ///     let read = UserSlice::new(uptr, len).reader();
 ///
-///     let mut buf = Vec::new();
+///     let mut buf = KVec::new();
 ///     read.read_all(&mut buf, GFP_KERNEL)?;
 ///
 ///     // THIS IS A BUG! The bytes could have changed since we checked them.
@@ -130,7 +127,7 @@ impl UserSlice {
     /// Reads the entirety of the user slice, appending it to the end of the provided buffer.
     ///
     /// Fails with [`EFAULT`] if the read happens on a bad address.
-    pub fn read_all(self, buf: &mut Vec<u8>, flags: Flags) -> Result {
+    pub fn read_all(self, buf: &mut KVec<u8>, flags: Flags) -> Result {
         self.reader().read_all(buf, flags)
     }
 
@@ -291,9 +288,9 @@ impl UserSliceReader {
     /// Reads the entirety of the user slice, appending it to the end of the provided buffer.
     ///
     /// Fails with [`EFAULT`] if the read happens on a bad address.
-    pub fn read_all(mut self, buf: &mut Vec<u8>, flags: Flags) -> Result {
+    pub fn read_all(mut self, buf: &mut KVec<u8>, flags: Flags) -> Result {
         let len = self.length;
-        VecExt::<u8>::reserve(buf, len, flags)?;
+        buf.reserve(len, flags)?;
 
         // The call to `try_reserve` was successful, so the spare capacity is at least `len` bytes
         // long.
diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
index ab93111a048c..8d4ac914b48b 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -242,7 +242,7 @@ pub fn concat_idents(ts: TokenStream) -> TokenStream {
 /// #[pin_data]
 /// struct DriverData {
 ///     #[pin]
-///     queue: Mutex<Vec<Command>>,
+///     queue: Mutex<KVec<Command>>,
 ///     buf: KBox<[u8; 1024 * 1024]>,
 /// }
 /// ```
@@ -251,7 +251,7 @@ pub fn concat_idents(ts: TokenStream) -> TokenStream {
 /// #[pin_data(PinnedDrop)]
 /// struct DriverData {
 ///     #[pin]
-///     queue: Mutex<Vec<Command>>,
+///     queue: Mutex<KVec<Command>>,
 ///     buf: KBox<[u8; 1024 * 1024]>,
 ///     raw_info: *mut Info,
 /// }
@@ -281,7 +281,7 @@ pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream {
 /// #[pin_data(PinnedDrop)]
 /// struct DriverData {
 ///     #[pin]
-///     queue: Mutex<Vec<Command>>,
+///     queue: Mutex<KVec<Command>>,
 ///     buf: KBox<[u8; 1024 * 1024]>,
 ///     raw_info: *mut Info,
 /// }
diff --git a/samples/rust/rust_minimal.rs b/samples/rust/rust_minimal.rs
index 2a9eaab62d1c..4aaf117bf8e3 100644
--- a/samples/rust/rust_minimal.rs
+++ b/samples/rust/rust_minimal.rs
@@ -13,7 +13,7 @@ module! {
 }
 
 struct RustMinimal {
-    numbers: Vec<i32>,
+    numbers: KVec<i32>,
 }
 
 impl kernel::Module for RustMinimal {
@@ -21,7 +21,7 @@ impl kernel::Module for RustMinimal {
         pr_info!("Rust minimal sample (init)\n");
         pr_info!("Am I built-in? {}\n", !cfg!(MODULE));
 
-        let mut numbers = Vec::new();
+        let mut numbers = KVec::new();
         numbers.push(72, GFP_KERNEL)?;
         numbers.push(108, GFP_KERNEL)?;
         numbers.push(200, GFP_KERNEL)?;
-- 
cgit v1.2.3


From 718c4069896cabba5c39b637cbb7205927f16ae0 Mon Sep 17 00:00:00 2001
From: Dirk Behme <dirk.behme@de.bosch.com>
Date: Wed, 2 Oct 2024 07:03:01 +0200
Subject: rust: types: extend `Opaque` documentation

Update the `Opaque` documentation and add an example as proposed by
Miguel Ojeda in [1]. The documentation update is mainly taken from
Benno Lossin's description [2].

Cc: Nell Shamrell-Harrington <nells@linux.microsoft.com>
Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://rust-for-linux.zulipchat.com/#narrow/stream/291565/topic/x/near/467478085 [1]
Link: https://rust-for-linux.zulipchat.com/#narrow/stream/291565/topic/x/near/470498289 [2]
Co-developed-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Benno Lossin <benno.lossin@proton.me>
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Link: https://lore.kernel.org/r/20241002050301.1927545-1-dirk.behme@de.bosch.com
[ Used `expect`. Rewrapped docs. Added intra-doc link. Formatted
  example. Reworded to fix tag typo/order. Fixed `&mut` formatting
  as discussed. Added Benno's SOB and CDB as discussed. Shortened
  links. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
 rust/kernel/types.rs | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 52 insertions(+), 1 deletion(-)

(limited to 'rust/kernel/types.rs')

diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index ced143600eb1..fae80814fa1c 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -206,7 +206,58 @@ impl<T, F: FnOnce(T)> Drop for ScopeGuard<T, F> {
 
 /// Stores an opaque value.
 ///
-/// This is meant to be used with FFI objects that are never interpreted by Rust code.
+/// `Opaque<T>` is meant to be used with FFI objects that are never interpreted by Rust code.
+///
+/// It is used to wrap structs from the C side, like for example `Opaque<bindings::mutex>`.
+/// It gets rid of all the usual assumptions that Rust has for a value:
+///
+/// * The value is allowed to be uninitialized (for example have invalid bit patterns: `3` for a
+///   [`bool`]).
+/// * The value is allowed to be mutated, when a `&Opaque<T>` exists on the Rust side.
+/// * No uniqueness for mutable references: it is fine to have multiple `&mut Opaque<T>` point to
+///   the same value.
+/// * The value is not allowed to be shared with other threads (i.e. it is `!Sync`).
+///
+/// This has to be used for all values that the C side has access to, because it can't be ensured
+/// that the C side is adhering to the usual constraints that Rust needs.
+///
+/// Using `Opaque<T>` allows to continue to use references on the Rust side even for values shared
+/// with C.
+///
+/// # Examples
+///
+/// ```
+/// # #![expect(unreachable_pub, clippy::disallowed_names)]
+/// use kernel::types::Opaque;
+/// # // Emulate a C struct binding which is from C, maybe uninitialized or not, only the C side
+/// # // knows.
+/// # mod bindings {
+/// #     pub struct Foo {
+/// #         pub val: u8,
+/// #     }
+/// # }
+///
+/// // `foo.val` is assumed to be handled on the C side, so we use `Opaque` to wrap it.
+/// pub struct Foo {
+///     foo: Opaque<bindings::Foo>,
+/// }
+///
+/// impl Foo {
+///     pub fn get_val(&self) -> u8 {
+///         let ptr = Opaque::get(&self.foo);
+///
+///         // SAFETY: `Self` is valid from C side.
+///         unsafe { (*ptr).val }
+///     }
+/// }
+///
+/// // Create an instance of `Foo` with the `Opaque` wrapper.
+/// let foo = Foo {
+///     foo: Opaque::new(bindings::Foo { val: 0xdb }),
+/// };
+///
+/// assert_eq!(foo.get_val(), 0xdb);
+/// ```
 #[repr(transparent)]
 pub struct Opaque<T> {
     value: UnsafeCell<MaybeUninit<T>>,
-- 
cgit v1.2.3


From d072acda4862f095ec9056979b654cc06a22cc68 Mon Sep 17 00:00:00 2001
From: Gary Guo <gary@garyguo.net>
Date: Fri, 13 Sep 2024 22:29:23 +0100
Subject: rust: use custom FFI integer types

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 <gary@garyguo.net>
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 <ojeda@kernel.org>
---
 rust/Makefile                       | 39 ++++++++++++++++++++++++-------------
 rust/ffi.rs                         | 13 +++++++++++++
 rust/kernel/alloc/allocator.rs      |  2 +-
 rust/kernel/alloc/allocator_test.rs |  4 ++--
 rust/kernel/alloc/kbox.rs           | 12 ++++++------
 rust/kernel/block/mq/operations.rs  | 18 ++++++++---------
 rust/kernel/block/mq/raw_writer.rs  |  2 +-
 rust/kernel/block/mq/tag_set.rs     |  2 +-
 rust/kernel/error.rs                | 20 +++++++++----------
 rust/kernel/init.rs                 |  2 +-
 rust/kernel/lib.rs                  |  2 ++
 rust/kernel/net/phy.rs              | 16 +++++++--------
 rust/kernel/str.rs                  |  4 ++--
 rust/kernel/sync/arc.rs             |  6 +++---
 rust/kernel/sync/condvar.rs         |  2 +-
 rust/kernel/sync/lock.rs            |  2 +-
 rust/kernel/sync/lock/mutex.rs      |  2 +-
 rust/kernel/sync/lock/spinlock.rs   |  2 +-
 rust/kernel/task.rs                 |  8 ++------
 rust/kernel/time.rs                 |  4 ++--
 rust/kernel/types.rs                | 14 ++++++-------
 rust/kernel/uaccess.rs              |  6 +++---
 rust/macros/module.rs               |  8 ++++----
 23 files changed, 107 insertions(+), 83 deletions(-)
 create mode 100644 rust/ffi.rs

(limited to 'rust/kernel/types.rs')

diff --git a/rust/Makefile b/rust/Makefile
index fcec0e1d9762..f349e7b067ea 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -3,7 +3,7 @@
 # Where to place rustdoc generated documentation
 rustdoc_output := $(objtree)/Documentation/output/rust/rustdoc
 
-obj-$(CONFIG_RUST) += core.o compiler_builtins.o
+obj-$(CONFIG_RUST) += core.o compiler_builtins.o ffi.o
 always-$(CONFIG_RUST) += exports_core_generated.h
 
 # Missing prototypes are expected in the helpers since these are exported
@@ -103,10 +103,13 @@ rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
 rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE
 	+$(call if_changed,rustdoc)
 
-rustdoc-kernel: private rustc_target_flags = \
+rustdoc-ffi: $(src)/ffi.rs rustdoc-core FORCE
+	+$(call if_changed,rustdoc)
+
+rustdoc-kernel: private rustc_target_flags = --extern ffi \
     --extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so \
     --extern bindings --extern uapi
-rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \
+rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-ffi rustdoc-macros \
     rustdoc-compiler_builtins $(obj)/libmacros.so \
     $(obj)/bindings.o FORCE
 	+$(call if_changed,rustdoc)
@@ -124,12 +127,15 @@ quiet_cmd_rustc_test_library = RUSTC TL $<
 rusttestlib-build_error: $(src)/build_error.rs FORCE
 	+$(call if_changed,rustc_test_library)
 
+rusttestlib-ffi: $(src)/ffi.rs FORCE
+	+$(call if_changed,rustc_test_library)
+
 rusttestlib-macros: private rustc_target_flags = --extern proc_macro
 rusttestlib-macros: private rustc_test_library_proc = yes
 rusttestlib-macros: $(src)/macros/lib.rs FORCE
 	+$(call if_changed,rustc_test_library)
 
-rusttestlib-kernel: private rustc_target_flags = \
+rusttestlib-kernel: private rustc_target_flags = --extern ffi \
     --extern build_error --extern macros \
     --extern bindings --extern uapi
 rusttestlib-kernel: $(src)/kernel/lib.rs \
@@ -137,10 +143,12 @@ rusttestlib-kernel: $(src)/kernel/lib.rs \
     $(obj)/libmacros.so $(obj)/bindings.o FORCE
 	+$(call if_changed,rustc_test_library)
 
-rusttestlib-bindings: $(src)/bindings/lib.rs FORCE
+rusttestlib-bindings: private rustc_target_flags = --extern ffi
+rusttestlib-bindings: $(src)/bindings/lib.rs rusttestlib-ffi FORCE
 	+$(call if_changed,rustc_test_library)
 
-rusttestlib-uapi: $(src)/uapi/lib.rs FORCE
+rusttestlib-uapi: private rustc_target_flags = --extern ffi
+rusttestlib-uapi: $(src)/uapi/lib.rs rusttestlib-ffi FORCE
 	+$(call if_changed,rustc_test_library)
 
 quiet_cmd_rustdoc_test = RUSTDOC T $<
@@ -160,7 +168,7 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $<
 	mkdir -p $(objtree)/$(obj)/test/doctests/kernel; \
 	OBJTREE=$(abspath $(objtree)) \
 	$(RUSTDOC) --test $(rust_flags) \
-		-L$(objtree)/$(obj) --extern kernel \
+		-L$(objtree)/$(obj) --extern ffi --extern kernel \
 		--extern build_error --extern macros \
 		--extern bindings --extern uapi \
 		--no-run --crate-name kernel -Zunstable-options \
@@ -198,9 +206,9 @@ rusttest-macros: $(src)/macros/lib.rs \
 	+$(call if_changed,rustc_test)
 	+$(call if_changed,rustdoc_test)
 
-rusttest-kernel: private rustc_target_flags = \
+rusttest-kernel: private rustc_target_flags = --extern ffi \
     --extern build_error --extern macros --extern bindings --extern uapi
-rusttest-kernel: $(src)/kernel/lib.rs rusttestlib-kernel \
+rusttest-kernel: $(src)/kernel/lib.rs rusttestlib-ffi rusttestlib-kernel \
     rusttestlib-build_error rusttestlib-macros rusttestlib-bindings \
     rusttestlib-uapi FORCE
 	+$(call if_changed,rustc_test)
@@ -273,7 +281,7 @@ bindgen_c_flags_final = $(bindgen_c_flags_lto) -fno-builtin -D__BINDGEN__
 quiet_cmd_bindgen = BINDGEN $@
       cmd_bindgen = \
 	$(BINDGEN) $< $(bindgen_target_flags) \
-		--use-core --with-derive-default --ctypes-prefix core::ffi --no-layout-tests \
+		--use-core --with-derive-default --ctypes-prefix ffi --no-layout-tests \
 		--no-debug '.*' --enable-function-attribute-detection \
 		-o $@ -- $(bindgen_c_flags_final) -DMODULE \
 		$(bindgen_target_cflags) $(bindgen_target_extra)
@@ -401,18 +409,23 @@ $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
 $(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
 	+$(call if_changed_rule,rustc_library)
 
+$(obj)/ffi.o: $(src)/ffi.rs $(obj)/compiler_builtins.o FORCE
+	+$(call if_changed_rule,rustc_library)
+
+$(obj)/bindings.o: private rustc_target_flags = --extern ffi
 $(obj)/bindings.o: $(src)/bindings/lib.rs \
-    $(obj)/compiler_builtins.o \
+    $(obj)/ffi.o \
     $(obj)/bindings/bindings_generated.rs \
     $(obj)/bindings/bindings_helpers_generated.rs FORCE
 	+$(call if_changed_rule,rustc_library)
 
+$(obj)/uapi.o: private rustc_target_flags = --extern ffi
 $(obj)/uapi.o: $(src)/uapi/lib.rs \
-    $(obj)/compiler_builtins.o \
+    $(obj)/ffi.o \
     $(obj)/uapi/uapi_generated.rs FORCE
 	+$(call if_changed_rule,rustc_library)
 
-$(obj)/kernel.o: private rustc_target_flags = \
+$(obj)/kernel.o: private rustc_target_flags = --extern ffi \
     --extern build_error --extern macros --extern bindings --extern uapi
 $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/build_error.o \
     $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE
diff --git a/rust/ffi.rs b/rust/ffi.rs
new file mode 100644
index 000000000000..be153c4d551b
--- /dev/null
+++ b/rust/ffi.rs
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Foreign function interface (FFI) types.
+//!
+//! This crate provides mapping from C primitive types to Rust ones.
+//!
+//! The Rust [`core`] crate provides [`core::ffi`], which maps integer types to the platform default
+//! C ABI. The kernel does not use [`core::ffi`], so it can customise the mapping that deviates from
+//! the platform default.
+
+#![no_std]
+
+pub use core::ffi::*;
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index a041bbfdabec..439985e29fbc 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -58,7 +58,7 @@ fn aligned_size(new_layout: Layout) -> usize {
 ///
 /// One of the following: `krealloc`, `vrealloc`, `kvrealloc`.
 struct ReallocFunc(
-    unsafe extern "C" fn(*const core::ffi::c_void, usize, u32) -> *mut core::ffi::c_void,
+    unsafe extern "C" fn(*const crate::ffi::c_void, usize, u32) -> *mut crate::ffi::c_void,
 );
 
 impl ReallocFunc {
diff --git a/rust/kernel/alloc/allocator_test.rs b/rust/kernel/alloc/allocator_test.rs
index 54ca85964d4a..e3240d16040b 100644
--- a/rust/kernel/alloc/allocator_test.rs
+++ b/rust/kernel/alloc/allocator_test.rs
@@ -24,10 +24,10 @@ pub type KVmalloc = Kmalloc;
 
 extern "C" {
     #[link_name = "aligned_alloc"]
-    fn libc_aligned_alloc(align: usize, size: usize) -> *mut core::ffi::c_void;
+    fn libc_aligned_alloc(align: usize, size: usize) -> *mut crate::ffi::c_void;
 
     #[link_name = "free"]
-    fn libc_free(ptr: *mut core::ffi::c_void);
+    fn libc_free(ptr: *mut crate::ffi::c_void);
 }
 
 // SAFETY:
diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index d69c32496b86..9ce414361c2c 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -355,17 +355,17 @@ where
 {
     type Borrowed<'a> = &'a T;
 
-    fn into_foreign(self) -> *const core::ffi::c_void {
+    fn into_foreign(self) -> *const crate::ffi::c_void {
         Box::into_raw(self) as _
     }
 
-    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
+    unsafe fn from_foreign(ptr: *const crate::ffi::c_void) -> Self {
         // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
         // call to `Self::into_foreign`.
         unsafe { Box::from_raw(ptr as _) }
     }
 
-    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> &'a T {
+    unsafe fn borrow<'a>(ptr: *const crate::ffi::c_void) -> &'a T {
         // SAFETY: The safety requirements of this method ensure that the object remains alive and
         // immutable for the duration of 'a.
         unsafe { &*ptr.cast() }
@@ -378,18 +378,18 @@ where
 {
     type Borrowed<'a> = Pin<&'a T>;
 
-    fn into_foreign(self) -> *const core::ffi::c_void {
+    fn into_foreign(self) -> *const crate::ffi::c_void {
         // SAFETY: We are still treating the box as pinned.
         Box::into_raw(unsafe { Pin::into_inner_unchecked(self) }) as _
     }
 
-    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
+    unsafe fn from_foreign(ptr: *const crate::ffi::c_void) -> Self {
         // SAFETY: The safety requirements of this function ensure that `ptr` comes from a previous
         // call to `Self::into_foreign`.
         unsafe { Pin::new_unchecked(Box::from_raw(ptr as _)) }
     }
 
-    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> Pin<&'a T> {
+    unsafe fn borrow<'a>(ptr: *const crate::ffi::c_void) -> Pin<&'a T> {
         // SAFETY: The safety requirements for this function ensure that the object is still alive,
         // so it is safe to dereference the raw pointer.
         // The safety requirements of `from_foreign` also ensure that the object remains alive for
diff --git a/rust/kernel/block/mq/operations.rs b/rust/kernel/block/mq/operations.rs
index 9ba7fdfeb4b2..c8646d0d9866 100644
--- a/rust/kernel/block/mq/operations.rs
+++ b/rust/kernel/block/mq/operations.rs
@@ -131,7 +131,7 @@ impl<T: Operations> OperationsVTable<T> {
     unsafe extern "C" fn poll_callback(
         _hctx: *mut bindings::blk_mq_hw_ctx,
         _iob: *mut bindings::io_comp_batch,
-    ) -> core::ffi::c_int {
+    ) -> crate::ffi::c_int {
         T::poll().into()
     }
 
@@ -145,9 +145,9 @@ impl<T: Operations> OperationsVTable<T> {
     /// for the same context.
     unsafe extern "C" fn init_hctx_callback(
         _hctx: *mut bindings::blk_mq_hw_ctx,
-        _tagset_data: *mut core::ffi::c_void,
-        _hctx_idx: core::ffi::c_uint,
-    ) -> core::ffi::c_int {
+        _tagset_data: *mut crate::ffi::c_void,
+        _hctx_idx: crate::ffi::c_uint,
+    ) -> crate::ffi::c_int {
         from_result(|| Ok(0))
     }
 
@@ -159,7 +159,7 @@ impl<T: Operations> OperationsVTable<T> {
     /// This function may only be called by blk-mq C infrastructure.
     unsafe extern "C" fn exit_hctx_callback(
         _hctx: *mut bindings::blk_mq_hw_ctx,
-        _hctx_idx: core::ffi::c_uint,
+        _hctx_idx: crate::ffi::c_uint,
     ) {
     }
 
@@ -176,9 +176,9 @@ impl<T: Operations> OperationsVTable<T> {
     unsafe extern "C" fn init_request_callback(
         _set: *mut bindings::blk_mq_tag_set,
         rq: *mut bindings::request,
-        _hctx_idx: core::ffi::c_uint,
-        _numa_node: core::ffi::c_uint,
-    ) -> core::ffi::c_int {
+        _hctx_idx: crate::ffi::c_uint,
+        _numa_node: crate::ffi::c_uint,
+    ) -> crate::ffi::c_int {
         from_result(|| {
             // SAFETY: By the safety requirements of this function, `rq` points
             // to a valid allocation.
@@ -203,7 +203,7 @@ impl<T: Operations> OperationsVTable<T> {
     unsafe extern "C" fn exit_request_callback(
         _set: *mut bindings::blk_mq_tag_set,
         rq: *mut bindings::request,
-        _hctx_idx: core::ffi::c_uint,
+        _hctx_idx: crate::ffi::c_uint,
     ) {
         // SAFETY: The tagset invariants guarantee that all requests are allocated with extra memory
         // for the request data.
diff --git a/rust/kernel/block/mq/raw_writer.rs b/rust/kernel/block/mq/raw_writer.rs
index 9222465d670b..7e2159e4f6a6 100644
--- a/rust/kernel/block/mq/raw_writer.rs
+++ b/rust/kernel/block/mq/raw_writer.rs
@@ -25,7 +25,7 @@ impl<'a> RawWriter<'a> {
     }
 
     pub(crate) fn from_array<const N: usize>(
-        a: &'a mut [core::ffi::c_char; N],
+        a: &'a mut [crate::ffi::c_char; N],
     ) -> Result<RawWriter<'a>> {
         Self::new(
             // SAFETY: the buffer of `a` is valid for read and write as `u8` for
diff --git a/rust/kernel/block/mq/tag_set.rs b/rust/kernel/block/mq/tag_set.rs
index f9a1ca655a35..d7f175a05d99 100644
--- a/rust/kernel/block/mq/tag_set.rs
+++ b/rust/kernel/block/mq/tag_set.rs
@@ -53,7 +53,7 @@ impl<T: Operations> TagSet<T> {
                     queue_depth: num_tags,
                     cmd_size,
                     flags: bindings::BLK_MQ_F_SHOULD_MERGE,
-                    driver_data: core::ptr::null_mut::<core::ffi::c_void>(),
+                    driver_data: core::ptr::null_mut::<crate::ffi::c_void>(),
                     nr_maps: num_maps,
                     ..tag_set
                 }
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 7cd3bbab52f2..52c502432447 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -100,7 +100,7 @@ impl Error {
     ///
     /// It is a bug to pass an out-of-range `errno`. `EINVAL` would
     /// be returned in such a case.
-    pub fn from_errno(errno: core::ffi::c_int) -> Error {
+    pub fn from_errno(errno: crate::ffi::c_int) -> Error {
         if errno < -(bindings::MAX_ERRNO as i32) || errno >= 0 {
             // TODO: Make it a `WARN_ONCE` once available.
             crate::pr_warn!(
@@ -119,7 +119,7 @@ impl Error {
     /// Creates an [`Error`] from a kernel error code.
     ///
     /// Returns [`None`] if `errno` is out-of-range.
-    const fn try_from_errno(errno: core::ffi::c_int) -> Option<Error> {
+    const fn try_from_errno(errno: crate::ffi::c_int) -> Option<Error> {
         if errno < -(bindings::MAX_ERRNO as i32) || errno >= 0 {
             return None;
         }
@@ -133,7 +133,7 @@ impl Error {
     /// # Safety
     ///
     /// `errno` must be within error code range (i.e. `>= -MAX_ERRNO && < 0`).
-    const unsafe fn from_errno_unchecked(errno: core::ffi::c_int) -> Error {
+    const unsafe fn from_errno_unchecked(errno: crate::ffi::c_int) -> Error {
         // INVARIANT: The contract ensures the type invariant
         // will hold.
         // SAFETY: The caller guarantees `errno` is non-zero.
@@ -141,7 +141,7 @@ impl Error {
     }
 
     /// Returns the kernel error code.
-    pub fn to_errno(self) -> core::ffi::c_int {
+    pub fn to_errno(self) -> crate::ffi::c_int {
         self.0.get()
     }
 
@@ -259,7 +259,7 @@ pub type Result<T = (), E = Error> = core::result::Result<T, E>;
 
 /// Converts an integer as returned by a C kernel function to an error if it's negative, and
 /// `Ok(())` otherwise.
-pub fn to_result(err: core::ffi::c_int) -> Result {
+pub fn to_result(err: crate::ffi::c_int) -> Result {
     if err < 0 {
         Err(Error::from_errno(err))
     } else {
@@ -282,15 +282,15 @@ pub fn to_result(err: core::ffi::c_int) -> Result {
 /// fn devm_platform_ioremap_resource(
 ///     pdev: &mut PlatformDevice,
 ///     index: u32,
-/// ) -> Result<*mut core::ffi::c_void> {
+/// ) -> Result<*mut kernel::ffi::c_void> {
 ///     // SAFETY: `pdev` points to a valid platform device. There are no safety requirements
 ///     // on `index`.
 ///     from_err_ptr(unsafe { bindings::devm_platform_ioremap_resource(pdev.to_ptr(), index) })
 /// }
 /// ```
 pub fn from_err_ptr<T>(ptr: *mut T) -> Result<*mut T> {
-    // CAST: Casting a pointer to `*const core::ffi::c_void` is always valid.
-    let const_ptr: *const core::ffi::c_void = ptr.cast();
+    // CAST: Casting a pointer to `*const crate::ffi::c_void` is always valid.
+    let const_ptr: *const crate::ffi::c_void = ptr.cast();
     // SAFETY: The FFI function does not deref the pointer.
     if unsafe { bindings::IS_ERR(const_ptr) } {
         // SAFETY: The FFI function does not deref the pointer.
@@ -306,7 +306,7 @@ pub fn from_err_ptr<T>(ptr: *mut T) -> Result<*mut T> {
         //
         // SAFETY: `IS_ERR()` ensures `err` is a
         // negative value greater-or-equal to `-bindings::MAX_ERRNO`.
-        return Err(unsafe { Error::from_errno_unchecked(err as core::ffi::c_int) });
+        return Err(unsafe { Error::from_errno_unchecked(err as crate::ffi::c_int) });
     }
     Ok(ptr)
 }
@@ -326,7 +326,7 @@ pub fn from_err_ptr<T>(ptr: *mut T) -> Result<*mut T> {
 /// # use kernel::bindings;
 /// unsafe extern "C" fn probe_callback(
 ///     pdev: *mut bindings::platform_device,
-/// ) -> core::ffi::c_int {
+/// ) -> kernel::ffi::c_int {
 ///     from_result(|| {
 ///         let ptr = devm_alloc(pdev)?;
 ///         bindings::platform_set_drvdata(pdev, ptr);
diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs
index c9919ba0b683..347049df556b 100644
--- a/rust/kernel/init.rs
+++ b/rust/kernel/init.rs
@@ -133,7 +133,7 @@
 //! # }
 //! # // `Error::from_errno` is `pub(crate)` in the `kernel` crate, thus provide a workaround.
 //! # trait FromErrno {
-//! #     fn from_errno(errno: core::ffi::c_int) -> Error {
+//! #     fn from_errno(errno: kernel::ffi::c_int) -> Error {
 //! #         // Dummy error that can be constructed outside the `kernel` crate.
 //! #         Error::from(core::fmt::Error)
 //! #     }
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index b62451f64f6e..bf8d7f841f94 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -27,6 +27,8 @@ compile_error!("Missing kernel configuration for conditional compilation");
 // Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate).
 extern crate self as kernel;
 
+pub use ffi;
+
 pub mod alloc;
 #[cfg(CONFIG_BLOCK)]
 pub mod block;
diff --git a/rust/kernel/net/phy.rs b/rust/kernel/net/phy.rs
index 910ce867480a..beb62ec712c3 100644
--- a/rust/kernel/net/phy.rs
+++ b/rust/kernel/net/phy.rs
@@ -314,7 +314,7 @@ impl<T: Driver> Adapter<T> {
     /// `phydev` must be passed by the corresponding callback in `phy_driver`.
     unsafe extern "C" fn soft_reset_callback(
         phydev: *mut bindings::phy_device,
-    ) -> core::ffi::c_int {
+    ) -> crate::ffi::c_int {
         from_result(|| {
             // SAFETY: This callback is called only in contexts
             // where we hold `phy_device->lock`, so the accessors on
@@ -328,7 +328,7 @@ impl<T: Driver> Adapter<T> {
     /// # Safety
     ///
     /// `phydev` must be passed by the corresponding callback in `phy_driver`.
-    unsafe extern "C" fn probe_callback(phydev: *mut bindings::phy_device) -> core::ffi::c_int {
+    unsafe extern "C" fn probe_callback(phydev: *mut bindings::phy_device) -> crate::ffi::c_int {
         from_result(|| {
             // SAFETY: This callback is called only in contexts
             // where we can exclusively access `phy_device` because
@@ -345,7 +345,7 @@ impl<T: Driver> Adapter<T> {
     /// `phydev` must be passed by the corresponding callback in `phy_driver`.
     unsafe extern "C" fn get_features_callback(
         phydev: *mut bindings::phy_device,
-    ) -> core::ffi::c_int {
+    ) -> crate::ffi::c_int {
         from_result(|| {
             // SAFETY: This callback is called only in contexts
             // where we hold `phy_device->lock`, so the accessors on
@@ -359,7 +359,7 @@ impl<T: Driver> Adapter<T> {
     /// # Safety
     ///
     /// `phydev` must be passed by the corresponding callback in `phy_driver`.
-    unsafe extern "C" fn suspend_callback(phydev: *mut bindings::phy_device) -> core::ffi::c_int {
+    unsafe extern "C" fn suspend_callback(phydev: *mut bindings::phy_device) -> crate::ffi::c_int {
         from_result(|| {
             // SAFETY: The C core code ensures that the accessors on
             // `Device` are okay to call even though `phy_device->lock`
@@ -373,7 +373,7 @@ impl<T: Driver> Adapter<T> {
     /// # Safety
     ///
     /// `phydev` must be passed by the corresponding callback in `phy_driver`.
-    unsafe extern "C" fn resume_callback(phydev: *mut bindings::phy_device) -> core::ffi::c_int {
+    unsafe extern "C" fn resume_callback(phydev: *mut bindings::phy_device) -> crate::ffi::c_int {
         from_result(|| {
             // SAFETY: The C core code ensures that the accessors on
             // `Device` are okay to call even though `phy_device->lock`
@@ -389,7 +389,7 @@ impl<T: Driver> Adapter<T> {
     /// `phydev` must be passed by the corresponding callback in `phy_driver`.
     unsafe extern "C" fn config_aneg_callback(
         phydev: *mut bindings::phy_device,
-    ) -> core::ffi::c_int {
+    ) -> crate::ffi::c_int {
         from_result(|| {
             // SAFETY: This callback is called only in contexts
             // where we hold `phy_device->lock`, so the accessors on
@@ -405,7 +405,7 @@ impl<T: Driver> Adapter<T> {
     /// `phydev` must be passed by the corresponding callback in `phy_driver`.
     unsafe extern "C" fn read_status_callback(
         phydev: *mut bindings::phy_device,
-    ) -> core::ffi::c_int {
+    ) -> crate::ffi::c_int {
         from_result(|| {
             // SAFETY: This callback is called only in contexts
             // where we hold `phy_device->lock`, so the accessors on
@@ -421,7 +421,7 @@ impl<T: Driver> Adapter<T> {
     /// `phydev` must be passed by the corresponding callback in `phy_driver`.
     unsafe extern "C" fn match_phy_device_callback(
         phydev: *mut bindings::phy_device,
-    ) -> core::ffi::c_int {
+    ) -> crate::ffi::c_int {
         // SAFETY: This callback is called only in contexts
         // where we hold `phy_device->lock`, so the accessors on
         // `Device` are okay to call.
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index aff6baa521d4..d04c12a1426d 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -184,7 +184,7 @@ impl CStr {
     /// last at least `'a`. When `CStr` is alive, the memory pointed by `ptr`
     /// must not be mutated.
     #[inline]
-    pub unsafe fn from_char_ptr<'a>(ptr: *const core::ffi::c_char) -> &'a Self {
+    pub unsafe fn from_char_ptr<'a>(ptr: *const crate::ffi::c_char) -> &'a Self {
         // SAFETY: The safety precondition guarantees `ptr` is a valid pointer
         // to a `NUL`-terminated C string.
         let len = unsafe { bindings::strlen(ptr) } + 1;
@@ -247,7 +247,7 @@ impl CStr {
 
     /// Returns a C pointer to the string.
     #[inline]
-    pub const fn as_char_ptr(&self) -> *const core::ffi::c_char {
+    pub const fn as_char_ptr(&self) -> *const crate::ffi::c_char {
         self.0.as_ptr() as _
     }
 
diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs
index db9da352d588..fa4509406ee9 100644
--- a/rust/kernel/sync/arc.rs
+++ b/rust/kernel/sync/arc.rs
@@ -332,11 +332,11 @@ impl<T: ?Sized> Arc<T> {
 impl<T: 'static> ForeignOwnable for Arc<T> {
     type Borrowed<'a> = ArcBorrow<'a, T>;
 
-    fn into_foreign(self) -> *const core::ffi::c_void {
+    fn into_foreign(self) -> *const crate::ffi::c_void {
         ManuallyDrop::new(self).ptr.as_ptr() as _
     }
 
-    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> ArcBorrow<'a, T> {
+    unsafe fn borrow<'a>(ptr: *const crate::ffi::c_void) -> ArcBorrow<'a, T> {
         // By the safety requirement of this function, we know that `ptr` came from
         // a previous call to `Arc::into_foreign`.
         let inner = NonNull::new(ptr as *mut ArcInner<T>).unwrap();
@@ -346,7 +346,7 @@ impl<T: 'static> ForeignOwnable for Arc<T> {
         unsafe { ArcBorrow::new(inner) }
     }
 
-    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self {
+    unsafe fn from_foreign(ptr: *const crate::ffi::c_void) -> Self {
         // SAFETY: By the safety requirement of this function, we know that `ptr` came from
         // a previous call to `Arc::into_foreign`, which guarantees that `ptr` is valid and
         // holds a reference count increment that is transferrable to us.
diff --git a/rust/kernel/sync/condvar.rs b/rust/kernel/sync/condvar.rs
index a1a29c0bdb3a..7df565038d7d 100644
--- a/rust/kernel/sync/condvar.rs
+++ b/rust/kernel/sync/condvar.rs
@@ -7,6 +7,7 @@
 
 use super::{lock::Backend, lock::Guard, LockClassKey};
 use crate::{
+    ffi::{c_int, c_long},
     init::PinInit,
     pin_init,
     str::CStr,
@@ -14,7 +15,6 @@ use crate::{
     time::Jiffies,
     types::Opaque,
 };
-use core::ffi::{c_int, c_long};
 use core::marker::PhantomPinned;
 use core::ptr;
 use macros::pin_data;
diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs
index a5d89cebf106..6d3c8874eb26 100644
--- a/rust/kernel/sync/lock.rs
+++ b/rust/kernel/sync/lock.rs
@@ -49,7 +49,7 @@ pub unsafe trait Backend {
     /// remain valid for read indefinitely.
     unsafe fn init(
         ptr: *mut Self::State,
-        name: *const core::ffi::c_char,
+        name: *const crate::ffi::c_char,
         key: *mut bindings::lock_class_key,
     );
 
diff --git a/rust/kernel/sync/lock/mutex.rs b/rust/kernel/sync/lock/mutex.rs
index 9ce43ccb4515..0e946ebefce1 100644
--- a/rust/kernel/sync/lock/mutex.rs
+++ b/rust/kernel/sync/lock/mutex.rs
@@ -96,7 +96,7 @@ unsafe impl super::Backend for MutexBackend {
 
     unsafe fn init(
         ptr: *mut Self::State,
-        name: *const core::ffi::c_char,
+        name: *const crate::ffi::c_char,
         key: *mut bindings::lock_class_key,
     ) {
         // SAFETY: The safety requirements ensure that `ptr` is valid for writes, and `name` and
diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs
index 040dc16975a6..9f4d128bed98 100644
--- a/rust/kernel/sync/lock/spinlock.rs
+++ b/rust/kernel/sync/lock/spinlock.rs
@@ -95,7 +95,7 @@ unsafe impl super::Backend for SpinLockBackend {
 
     unsafe fn init(
         ptr: *mut Self::State,
-        name: *const core::ffi::c_char,
+        name: *const crate::ffi::c_char,
         key: *mut bindings::lock_class_key,
     ) {
         // SAFETY: The safety requirements ensure that `ptr` is valid for writes, and `name` and
diff --git a/rust/kernel/task.rs b/rust/kernel/task.rs
index 55dff7e088bf..5bce090a3869 100644
--- a/rust/kernel/task.rs
+++ b/rust/kernel/task.rs
@@ -4,13 +4,9 @@
 //!
 //! C header: [`include/linux/sched.h`](srctree/include/linux/sched.h).
 
+use crate::ffi::{c_int, c_long, c_uint};
 use crate::types::Opaque;
-use core::{
-    ffi::{c_int, c_long, c_uint},
-    marker::PhantomData,
-    ops::Deref,
-    ptr,
-};
+use core::{marker::PhantomData, ops::Deref, ptr};
 
 /// A sentinel value used for infinite timeouts.
 pub const MAX_SCHEDULE_TIMEOUT: c_long = c_long::MAX;
diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs
index e3bb5e89f88d..379c0f5772e5 100644
--- a/rust/kernel/time.rs
+++ b/rust/kernel/time.rs
@@ -12,10 +12,10 @@
 pub const NSEC_PER_MSEC: i64 = bindings::NSEC_PER_MSEC as i64;
 
 /// The time unit of Linux kernel. One jiffy equals (1/HZ) second.
-pub type Jiffies = core::ffi::c_ulong;
+pub type Jiffies = crate::ffi::c_ulong;
 
 /// The millisecond time unit.
-pub type Msecs = core::ffi::c_uint;
+pub type Msecs = crate::ffi::c_uint;
 
 /// Converts milliseconds to jiffies.
 #[inline]
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs
index fae80814fa1c..a7eaa29f08a4 100644
--- a/rust/kernel/types.rs
+++ b/rust/kernel/types.rs
@@ -29,7 +29,7 @@ pub trait ForeignOwnable: Sized {
     /// For example, it might be invalid, dangling or pointing to uninitialized memory. Using it in
     /// any way except for [`ForeignOwnable::from_foreign`], [`ForeignOwnable::borrow`],
     /// [`ForeignOwnable::try_from_foreign`] can result in undefined behavior.
-    fn into_foreign(self) -> *const core::ffi::c_void;
+    fn into_foreign(self) -> *const crate::ffi::c_void;
 
     /// Borrows a foreign-owned object.
     ///
@@ -37,7 +37,7 @@ pub trait ForeignOwnable: Sized {
     ///
     /// `ptr` must have been returned by a previous call to [`ForeignOwnable::into_foreign`] for
     /// which a previous matching [`ForeignOwnable::from_foreign`] hasn't been called yet.
-    unsafe fn borrow<'a>(ptr: *const core::ffi::c_void) -> Self::Borrowed<'a>;
+    unsafe fn borrow<'a>(ptr: *const crate::ffi::c_void) -> Self::Borrowed<'a>;
 
     /// Converts a foreign-owned object back to a Rust-owned one.
     ///
@@ -47,7 +47,7 @@ pub trait ForeignOwnable: Sized {
     /// which a previous matching [`ForeignOwnable::from_foreign`] hasn't been called yet.
     /// Additionally, all instances (if any) of values returned by [`ForeignOwnable::borrow`] for
     /// this object must have been dropped.
-    unsafe fn from_foreign(ptr: *const core::ffi::c_void) -> Self;
+    unsafe fn from_foreign(ptr: *const crate::ffi::c_void) -> Self;
 
     /// Tries to convert a foreign-owned object back to a Rust-owned one.
     ///
@@ -58,7 +58,7 @@ pub trait ForeignOwnable: Sized {
     ///
     /// `ptr` must either be null or satisfy the safety requirements for
     /// [`ForeignOwnable::from_foreign`].
-    unsafe fn try_from_foreign(ptr: *const core::ffi::c_void) -> Option<Self> {
+    unsafe fn try_from_foreign(ptr: *const crate::ffi::c_void) -> Option<Self> {
         if ptr.is_null() {
             None
         } else {
@@ -72,13 +72,13 @@ pub trait ForeignOwnable: Sized {
 impl ForeignOwnable for () {
     type Borrowed<'a> = ();
 
-    fn into_foreign(self) -> *const core::ffi::c_void {
+    fn into_foreign(self) -> *const crate::ffi::c_void {
         core::ptr::NonNull::dangling().as_ptr()
     }
 
-    unsafe fn borrow<'a>(_: *const core::ffi::c_void) -> Self::Borrowed<'a> {}
+    unsafe fn borrow<'a>(_: *const crate::ffi::c_void) -> Self::Borrowed<'a> {}
 
-    unsafe fn from_foreign(_: *const core::ffi::c_void) -> Self {}
+    unsafe fn from_foreign(_: *const crate::ffi::c_void) -> Self {}
 }
 
 /// Runs a cleanup function/closure when dropped.
diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs
index 2c953ba53c77..05b0b8d13b10 100644
--- a/rust/kernel/uaccess.rs
+++ b/rust/kernel/uaccess.rs
@@ -8,10 +8,10 @@ use crate::{
     alloc::Flags,
     bindings,
     error::Result,
+    ffi::{c_ulong, c_void},
     prelude::*,
     transmute::{AsBytes, FromBytes},
 };
-use core::ffi::{c_ulong, c_void};
 use core::mem::{size_of, MaybeUninit};
 
 /// The type used for userspace addresses.
@@ -45,7 +45,7 @@ pub type UserPtr = usize;
 /// every byte in the region.
 ///
 /// ```no_run
-/// use core::ffi::c_void;
+/// use kernel::ffi::c_void;
 /// use kernel::error::Result;
 /// use kernel::uaccess::{UserPtr, UserSlice};
 ///
@@ -67,7 +67,7 @@ pub type UserPtr = usize;
 /// Example illustrating a TOCTOU (time-of-check to time-of-use) bug.
 ///
 /// ```no_run
-/// use core::ffi::c_void;
+/// use kernel::ffi::c_void;
 /// use kernel::error::{code::EINVAL, Result};
 /// use kernel::uaccess::{UserPtr, UserSlice};
 ///
diff --git a/rust/macros/module.rs b/rust/macros/module.rs
index aef3b132f32b..e7a087b7e884 100644
--- a/rust/macros/module.rs
+++ b/rust/macros/module.rs
@@ -253,7 +253,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
                     #[doc(hidden)]
                     #[no_mangle]
                     #[link_section = \".init.text\"]
-                    pub unsafe extern \"C\" fn init_module() -> core::ffi::c_int {{
+                    pub unsafe extern \"C\" fn init_module() -> kernel::ffi::c_int {{
                         // SAFETY: This function is inaccessible to the outside due to the double
                         // module wrapping it. It is called exactly once by the C side via its
                         // unique name.
@@ -292,7 +292,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
                     #[doc(hidden)]
                     #[link_section = \"{initcall_section}\"]
                     #[used]
-                    pub static __{name}_initcall: extern \"C\" fn() -> core::ffi::c_int = __{name}_init;
+                    pub static __{name}_initcall: extern \"C\" fn() -> kernel::ffi::c_int = __{name}_init;
 
                     #[cfg(not(MODULE))]
                     #[cfg(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)]
@@ -307,7 +307,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
                     #[cfg(not(MODULE))]
                     #[doc(hidden)]
                     #[no_mangle]
-                    pub extern \"C\" fn __{name}_init() -> core::ffi::c_int {{
+                    pub extern \"C\" fn __{name}_init() -> kernel::ffi::c_int {{
                         // SAFETY: This function is inaccessible to the outside due to the double
                         // module wrapping it. It is called exactly once by the C side via its
                         // placement above in the initcall section.
@@ -330,7 +330,7 @@ pub(crate) fn module(ts: TokenStream) -> TokenStream {
                     /// # Safety
                     ///
                     /// This function must only be called once.
-                    unsafe fn __init() -> core::ffi::c_int {{
+                    unsafe fn __init() -> kernel::ffi::c_int {{
                         match <{type_} as kernel::Module>::init(&super::super::THIS_MODULE) {{
                             Ok(m) => {{
                                 // SAFETY: No data race, since `__MOD` can only be accessed by this
-- 
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