linux-kernel - [PATCH v4 0/2] rust: add `Alignment` type

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250821-num-v4-0-1f3a425d7244@nvidia.com>
Date: Thu, 21 Aug 2025 21:42:16 +0900
From: Alexandre Courbot <acourbot@...dia.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>, 
 Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, 
 Björn Roy Baron <bjorn3_gh@...tonmail.com>, 
 Benno Lossin <lossin@...nel.org>, Andreas Hindborg <a.hindborg@...nel.org>, 
 Alice Ryhl <aliceryhl@...gle.com>, Trevor Gross <tmgross@...ch.edu>, 
 Danilo Krummrich <dakr@...nel.org>
Cc: linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org, 
 nouveau@...ts.freedesktop.org, Alexandre Courbot <acourbot@...dia.com>
Subject: [PATCH v4 0/2] rust: add `Alignment` type

Basically a resend of the previous version, plus fixes to build with the
MSRV (1.78).

The first patch makes two additions:

- Bring an equivalent of the nightly upstream `Alignment` type [2] with
  an identical public interface,
- Add a new `Alignable` extension trait that provides a way to align
  values up or down according to an `Alignment`, and implement it on
  unsigned integer types.

The second patch makes use of these in the Nova driver.

[3] is recommended as a dependency, a small cleanup preventing an unwrap
upon applying this series.

[1] https://github.com/rust-lang/libs-team/issues/631
[2] https://doc.rust-lang.org/std/ptr/struct.Alignment.html
[3] https://lore.kernel.org/rust-for-linux/20250808-falcondma_256b-v1-1-15f911d89ffd@nvidia.com/

Signed-off-by: Alexandre Courbot <acourbot@...dia.com>
---
Changes in v4:
- Add the `generic_nonzero` feature (stabilized in Rust 1.79) to fix
  build with Rust 1.78.
- Import `core::mem::align_of` for older Rust versions (as the patch
  adding it to the prelude is not attainable from nova-next yet).
- Link to v3: https://lore.kernel.org/r/20250812-num-v3-0-569d6fe1839f@nvidia.com

Changes in v3:
- Move `align_down` and `align_up` into their own `Alignable` trait.
  (thanks Miguel!)
- Fix `Alignment::mask` implementation to match upstream's.
- Add missing `SAFETY:` comments.
- Improve grammar on a few hard-to-parse comments.
- Link to v2: https://lore.kernel.org/r/20250804-num-v2-0-a96b9ca6eb02@nvidia.com

Changes in v2:
- Remove `last_checked_bit` (use Rust's `checked_ilog2` instead).
- Port Rust nightly `Alignment` type and extend it with `align_down` and
  `align_up` methods.
- Link to v1: https://lore.kernel.org/r/20250620-num-v1-0-7ec3d3fb06c9@nvidia.com

Changes since split from the nova-core series:
- Rename `fls` to `last_set_bit`,
- Generate per-type doctests,
- Add invariants section to `PowerOfTwo`.
- Do not use reference to `self` in `PowerOfTwo` methods since it
  implements `Copy`,
  - Use #[derive] where possible instead of implementing traits
    manually,
    - Remove `Deref` and `Borrow` implementations.

---
Alexandre Courbot (2):
      rust: add `Alignment` type
      gpu: nova-core: use Alignment for alignment-related operations

 Documentation/gpu/nova/core/todo.rst |   1 -
 drivers/gpu/nova-core/fb.rs          |   6 +-
 drivers/gpu/nova-core/vbios.rs       |   4 +-
 rust/kernel/lib.rs                   |   2 +
 rust/kernel/ptr.rs                   | 219 +++++++++++++++++++++++++++++++++++
 5 files changed, 226 insertions(+), 6 deletions(-)
---
base-commit: 062b3e4a1f880f104a8d4b90b767788786aa7b78
change-id: 20250620-num-9420281c02c7
prerequisite-message-id: <20250808-falcondma_256b-v1-1-15f911d89ffd@...dia.com>
prerequisite-patch-id: 2439f5f9b560ee4867716f0018b5326dcd72cda3

Best regards,
-- 
Alexandre Courbot <acourbot@...dia.com>