Merge tag 'rust-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux

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

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

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

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

  'kernel' crate:

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

         warn_on!(value == 42);

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

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

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

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

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

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

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

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

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

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

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

   - 'dma' module:

      - Clarify wording and be consistent in 'coherent' nomenclature

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

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

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

      - Implement 'CoherentAllocation::dma_handle_with_offset()'

   - 'time' module:

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

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

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

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

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

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

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

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

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

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

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

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

   - 'rbtree' module: add 'is_empty' method

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

  'pin-init' crate:

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

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

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

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

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

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

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

  MAINTAINERS:

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

  And a few other cleanups and improvements"

* tag 'rust-6.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (76 commits)
  rust: Add warn_on macro
  arm64/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  riscv/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  x86/bug: Add ARCH_WARN_ASM macro for BUG/WARN asm code sharing with Rust
  rust: kernel: move ARef and AlwaysRefCounted to sync::aref
  rust: sync: fix safety comment for `static_lock_class`
  rust: types: remove `Either<L, R>`
  rust: kernel: use `core::ffi::CStr` method names
  rust: str: add `CStr` methods matching `core::ffi::CStr`
  rust: str: remove unnecessary qualification
  rust: use `kernel::{fmt,prelude::fmt!}`
  rust: kernel: add `fmt` module
  rust: kernel: remove `fmt!`, fix clippy::uninlined-format-args
  scripts: rust: emit path candidates in panic message
  scripts: rust: replace length checks with match
  rust: list: remove nonexistent generic parameter in link
  rust: bits: add support for bits/genmask macros
  rust: list: remove OFFSET constants
  rust: list: add `impl_list_item!` examples
  rust: list: use fully qualified path
  ...

1 files changed, 203 insertions, 0 deletions

diff --git a/rust/kernel/bits.rs b/rust/kernel/bits.rs
new file mode 100644
index 000000000000..553d50265883
--- /dev/null
+++ b/rust/kernel/bits.rs
@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Bit manipulation macros.
+//!
+//! C header: [`include/linux/bits.h`](srctree/include/linux/bits.h)
+
+use crate::prelude::*;
+use core::ops::RangeInclusive;
+use macros::paste;
+
+macro_rules! impl_bit_fn {
+    (
+        $ty:ty
+    ) => {
+        paste! {
+            /// Computes `1 << n` if `n` is in bounds, i.e.: if `n` is smaller than
+            /// the maximum number of bits supported by the type.
+            ///
+            /// Returns [`None`] otherwise.
+            #[inline]
+            pub fn [<checked_bit_ $ty>](n: u32) -> Option<$ty> {
+                (1 as $ty).checked_shl(n)
+            }
+
+            /// Computes `1 << n` by performing a compile-time assertion that `n` is
+            /// in bounds.
+            ///
+            /// This version is the default and should be used if `n` is known at
+            /// compile time.
+            #[inline]
+            pub const fn [<bit_ $ty>](n: u32) -> $ty {
+                build_assert!(n < <$ty>::BITS);
+                (1 as $ty) << n
+            }
+        }
+    };
+}
+
+impl_bit_fn!(u64);
+impl_bit_fn!(u32);
+impl_bit_fn!(u16);
+impl_bit_fn!(u8);
+
+macro_rules! impl_genmask_fn {
+    (
+        $ty:ty,
+        $(#[$genmask_checked_ex:meta])*,
+        $(#[$genmask_ex:meta])*
+    ) => {
+        paste! {
+            /// Creates a contiguous bitmask for the given range by validating
+            /// the range at runtime.
+            ///
+            /// Returns [`None`] if the range is invalid, i.e.: if the start is
+            /// greater than the end or if the range is outside of the
+            /// representable range for the type.
+            $(#[$genmask_checked_ex])*
+            #[inline]
+            pub fn [<genmask_checked_ $ty>](range: RangeInclusive<u32>) -> Option<$ty> {
+                let start = *range.start();
+                let end = *range.end();
+
+                if start > end {
+                    return None;
+                }
+
+                let high = [<checked_bit_ $ty>](end)?;
+                let low = [<checked_bit_ $ty>](start)?;
+                Some((high | (high - 1)) & !(low - 1))
+            }
+
+            /// Creates a compile-time contiguous bitmask for the given range by
+            /// performing a compile-time assertion that the range is valid.
+            ///
+            /// This version is the default and should be used if the range is known
+            /// at compile time.
+            $(#[$genmask_ex])*
+            #[inline]
+            pub const fn [<genmask_ $ty>](range: RangeInclusive<u32>) -> $ty {
+                let start = *range.start();
+                let end = *range.end();
+
+                build_assert!(start <= end);
+
+                let high = [<bit_ $ty>](end);
+                let low = [<bit_ $ty>](start);
+                (high | (high - 1)) & !(low - 1)
+            }
+        }
+    };
+}
+
+impl_genmask_fn!(
+    u64,
+    /// # Examples
+    ///
+    /// ```
+    /// # #![expect(clippy::reversed_empty_ranges)]
+    /// # use kernel::bits::genmask_checked_u64;
+    /// assert_eq!(genmask_checked_u64(0..=0), Some(0b1));
+    /// assert_eq!(genmask_checked_u64(0..=63), Some(u64::MAX));
+    /// assert_eq!(genmask_checked_u64(21..=39), Some(0x0000_00ff_ffe0_0000));
+    ///
+    /// // `80` is out of the supported bit range.
+    /// assert_eq!(genmask_checked_u64(21..=80), None);
+    ///
+    /// // Invalid range where the start is bigger than the end.
+    /// assert_eq!(genmask_checked_u64(15..=8), None);
+    /// ```
+    ,
+    /// # Examples
+    ///
+    /// ```
+    /// # use kernel::bits::genmask_u64;
+    /// assert_eq!(genmask_u64(21..=39), 0x0000_00ff_ffe0_0000);
+    /// assert_eq!(genmask_u64(0..=0), 0b1);
+    /// assert_eq!(genmask_u64(0..=63), u64::MAX);
+    /// ```
+);
+
+impl_genmask_fn!(
+    u32,
+    /// # Examples
+    ///
+    /// ```
+    /// # #![expect(clippy::reversed_empty_ranges)]
+    /// # use kernel::bits::genmask_checked_u32;
+    /// assert_eq!(genmask_checked_u32(0..=0), Some(0b1));
+    /// assert_eq!(genmask_checked_u32(0..=31), Some(u32::MAX));
+    /// assert_eq!(genmask_checked_u32(21..=31), Some(0xffe0_0000));
+    ///
+    /// // `40` is out of the supported bit range.
+    /// assert_eq!(genmask_checked_u32(21..=40), None);
+    ///
+    /// // Invalid range where the start is bigger than the end.
+    /// assert_eq!(genmask_checked_u32(15..=8), None);
+    /// ```
+    ,
+    /// # Examples
+    ///
+    /// ```
+    /// # use kernel::bits::genmask_u32;
+    /// assert_eq!(genmask_u32(21..=31), 0xffe0_0000);
+    /// assert_eq!(genmask_u32(0..=0), 0b1);
+    /// assert_eq!(genmask_u32(0..=31), u32::MAX);
+    /// ```
+);
+
+impl_genmask_fn!(
+    u16,
+    /// # Examples
+    ///
+    /// ```
+    /// # #![expect(clippy::reversed_empty_ranges)]
+    /// # use kernel::bits::genmask_checked_u16;
+    /// assert_eq!(genmask_checked_u16(0..=0), Some(0b1));
+    /// assert_eq!(genmask_checked_u16(0..=15), Some(u16::MAX));
+    /// assert_eq!(genmask_checked_u16(6..=15), Some(0xffc0));
+    ///
+    /// // `20` is out of the supported bit range.
+    /// assert_eq!(genmask_checked_u16(6..=20), None);
+    ///
+    /// // Invalid range where the start is bigger than the end.
+    /// assert_eq!(genmask_checked_u16(10..=5), None);
+    /// ```
+    ,
+    /// # Examples
+    ///
+    /// ```
+    /// # use kernel::bits::genmask_u16;
+    /// assert_eq!(genmask_u16(6..=15), 0xffc0);
+    /// assert_eq!(genmask_u16(0..=0), 0b1);
+    /// assert_eq!(genmask_u16(0..=15), u16::MAX);
+    /// ```
+);
+
+impl_genmask_fn!(
+    u8,
+    /// # Examples
+    ///
+    /// ```
+    /// # #![expect(clippy::reversed_empty_ranges)]
+    /// # use kernel::bits::genmask_checked_u8;
+    /// assert_eq!(genmask_checked_u8(0..=0), Some(0b1));
+    /// assert_eq!(genmask_checked_u8(0..=7), Some(u8::MAX));
+    /// assert_eq!(genmask_checked_u8(6..=7), Some(0xc0));
+    ///
+    /// // `10` is out of the supported bit range.
+    /// assert_eq!(genmask_checked_u8(6..=10), None);
+    ///
+    /// // Invalid range where the start is bigger than the end.
+    /// assert_eq!(genmask_checked_u8(5..=2), None);
+    /// ```
+    ,
+    /// # Examples
+    ///
+    /// ```
+    /// # use kernel::bits::genmask_u8;
+    /// assert_eq!(genmask_u8(6..=7), 0xc0);
+    /// assert_eq!(genmask_u8(0..=0), 0b1);
+    /// assert_eq!(genmask_u8(0..=7), u8::MAX);
+    /// ```
+);