From nobody Wed Oct 8 00:55:45 2025 Received: from mail-pg1-f174.google.com (mail-pg1-f174.google.com [209.85.215.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D919A27735; Fri, 4 Jul 2025 04:10:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751602246; cv=none; b=p1hH7h63p2jYahyw+/mTtIzKDHmYCUH+sYZ+y+HwIRmQjBovKQTaWlBBjVbYdDTglodRXQyIxNLY80XZmgDW1aFd0Vy5fXEXA0J0ozSNyZivvQPlMA2MbKLUNGWIUov5gbc3yb2JiUh72Stc4MWYGaROZ5lOMwRAU+Xr3uPdkvw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751602246; c=relaxed/simple; bh=eNbksy8AOjNuAyIZhrJCd/5+MipiS6qBpV2tUg3eZjY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kzCdKRVjSxFw+WgEcwAUQzjD1GvhYdMp+KfqFggm14JqTOoz3eSOBYUxe+4aCmeIjJUDmqKZ31I4sEflNxXFcL9+c95FDXHqqR16IxXV6i1Y5VSYIr5y3C6CgFasCx59atnCBQaazfnUCp67NSx2gTsdcGzJw6yGBXv1ij0xwY8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=TgRWf10Z; arc=none smtp.client-ip=209.85.215.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TgRWf10Z" Received: by mail-pg1-f174.google.com with SMTP id 41be03b00d2f7-b31e0ead80eso429385a12.0; Thu, 03 Jul 2025 21:10:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1751602244; x=1752207044; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=mLlW3cPUYyFonekL6aq/AJFh/MLlfDz3CJwgfxqEOeU=; b=TgRWf10Z5F+xYUle1GlauQNrjgjHbv1JTnLCO4Ohd8EuLpnx9vvncdc/PErq2rCXer hM5DlINoVVR4c+S2g1MMvclK3BCfDvQ5VF5Gw2etq2YemE14/7kTl+IJEqQvOiAYB9h/ mJ+5iHHY1XeJom3W+lbMEqFyO5aLq1HtbTtO27BufPcW/6f6rAnMnsriOWFMajQEhOxz LGz3n/i5Niqmu9vv8k/Bx10JFe0IixcPUSHZ3L+lFwdGDro4hSu+F7Hvn3C/e17/6xzg f2wXduuzncIuylex3jgvzGa5EKRjcvnjJRDg7/H6MUzF4Y0jFKOc2nuzXcvrq7bDOXi9 tfLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1751602244; x=1752207044; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=mLlW3cPUYyFonekL6aq/AJFh/MLlfDz3CJwgfxqEOeU=; b=XXd1fmeZQ5obntM1H2au6UDIaH/JjIsMGQroK3bLSEkBlZORD3sBnbMa/+WR1NW69v m+mloqmAKCBK/UWO7wt1j/+ZnlFV7+oZxbF0QYxE3m+cyM8g7FtM85oMbPcy+YEvDM5v r0EkNapd/8lCn1n24mv4g9ojxEGxqUp+3uQYAJ7pPjQzsECoVcaSLJOecAQbD0atncgb UGuMurebrOcfUah/hUMFXEdeXuun4Qt4mPHC7+vejqt2ROcA9AZ2D+woEDcVSu0nO4Ae Kel2+Wp1VqRs6n/c6TRg13dcJMYMXHq3/ybIpHnsNAErqAHbwgnVvAA2XJLaEmMqs3uJ nlcA== X-Forwarded-Encrypted: i=1; AJvYcCUdtmQBEm+JjEXIiANezW/utviDVwVXYQtlmh1pd+90xR8b5HCvwAg51yIruGbVN7LvWSNZuvrl@vger.kernel.org, AJvYcCV7AcBKyH+4xlow5LB6NDY2g6k7Z4l549AiKU+XrWUlacqrqpQsd1i0jFC4FKrfStqvVIF9s1inDFZ0fi9c@vger.kernel.org, AJvYcCWPOCppkjr3NPtCkowrTTlkafKLh4oTAZ8Seh5Y1b5bYBLt/MFKZa+h4IaJEwOHn8HThLSsP10MBPti@vger.kernel.org, AJvYcCWuxn3oNk84FB5ROsUaJXrNyZRMrctNJR1I6Eeguwc4sGuYO5lXexdvL9KCnRJIYB09euMNnUW/8bwm@vger.kernel.org, AJvYcCXzz6A5FpAqZAy+QHTz2bByMYCAr/THvjqmnXOvuhgqXpaDlvg/0/VHuEySQb91NkaGnykPDJIT+/CRjAqWh+s=@vger.kernel.org X-Gm-Message-State: AOJu0Ywq94oxhbTRjZ3fBRdmxVuLhrRrGfd+sgngwo78G8B60pT/FUXZ sXDkSfa/T7RLLI9FNXUyMnc4RjkAlIq6u0Cv8Pof8lTUBndJZdkYZhCy X-Gm-Gg: ASbGnct5iGlbx3Hhaidv6oxS73kDEJpjTQkK9/6BvPZheGMq6uk6HayVgkwRtovfBe9 TPLNUlat1pO/5Uv4oYThR7P7E0RWdVHBAhmjDJw00yqk/irjQEWnZpttWCjwor2vi4qrgctOOio 0EZ5FxDIIm+x2nOWEiOgUPYY3B182rLXwmDWZR6DNQPHfCKqhIuPlo/dMonRxOh+Y8TQp69o8Ox Ur+06Q3D/TxDROkR+cxpv5FKSsAGJw3W57p/ogndih9/hpUhpHT45Jty2BQrWHF4D9f+K+FtM/I TzhL+1EnxHwGaKzKK3sQhLTUWaVsng0V026ml6mvlQrMyJJkXOKmuCV5tsUylYu0z+sAPcI2SoG SxNaTTmzw6cazU9bWQfdYy8648e6Ajm4Co7utMPPKEnIGvw== X-Google-Smtp-Source: AGHT+IHB5benb40weVsS/om26EMWrjUvnSEItDPkOuKwEXM1nyxNNczxCzTygFKqVoraa01oZ59IxA== X-Received: by 2002:a05:6a21:6185:b0:1f5:619a:7f4c with SMTP id adf61e73a8af0-225c0de0c35mr2051539637.29.1751602243963; Thu, 03 Jul 2025 21:10:43 -0700 (PDT) Received: from bee.. (p5332007-ipxg23901hodogaya.kanagawa.ocn.ne.jp. [180.34.120.7]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-74ce35ccb9esm1055290b3a.50.2025.07.03.21.10.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Jul 2025 21:10:43 -0700 (PDT) From: FUJITA Tomonori To: alex.gaynor@gmail.com, dakr@kernel.org, gregkh@linuxfoundation.org, ojeda@kernel.org, rafael@kernel.org, robh@kernel.org, saravanak@google.com Cc: a.hindborg@kernel.org, aliceryhl@google.com, bhelgaas@google.com, bjorn3_gh@protonmail.com, boqun.feng@gmail.com, david.m.ertman@intel.com, devicetree@vger.kernel.org, gary@garyguo.net, ira.weiny@intel.com, kwilczynski@kernel.org, leon@kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, lossin@kernel.org, netdev@vger.kernel.org, rust-for-linux@vger.kernel.org, tmgross@umich.edu Subject: [PATCH v3 1/3] rust: device_id: split out index support into a separate trait Date: Fri, 4 Jul 2025 13:10:01 +0900 Message-ID: <20250704041003.734033-2-fujita.tomonori@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250704041003.734033-1-fujita.tomonori@gmail.com> References: <20250704041003.734033-1-fujita.tomonori@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Introduce a new trait `RawDeviceIdIndex`, which extends `RawDeviceId` to provide support for device ID types that include an index or context field (e.g., `driver_data`). This separates the concerns of layout compatibility and index-based data embedding, and allows `RawDeviceId` to be implemented for types that do not contain a `driver_data` field. Several such structures are defined in include/linux/mod_devicetable.h. Refactor `IdArray::new()` into a generic `build()` function, which takes an optional offset. Based on the presence of `RawDeviceIdIndex`, index writing is conditionally enabled. A new `new_without_index()` constructor is also provided for use cases where no index should be written. This refactoring is a preparation for enabling the PHY abstractions to use device_id trait. Acked-by: Danilo Krummrich Signed-off-by: FUJITA Tomonori Reviewed-by: Trevor Gross --- rust/kernel/auxiliary.rs | 11 ++--- rust/kernel/device_id.rs | 91 ++++++++++++++++++++++++++++------------ rust/kernel/of.rs | 15 ++++--- rust/kernel/pci.rs | 11 ++--- 4 files changed, 87 insertions(+), 41 deletions(-) diff --git a/rust/kernel/auxiliary.rs b/rust/kernel/auxiliary.rs index d2cfe1eeefb6..526cb6dcad52 100644 --- a/rust/kernel/auxiliary.rs +++ b/rust/kernel/auxiliary.rs @@ -6,7 +6,7 @@ =20 use crate::{ bindings, container_of, device, - device_id::RawDeviceId, + device_id::{RawDeviceId, RawDeviceIdIndex}, driver, error::{to_result, Result}, prelude::*, @@ -140,13 +140,14 @@ pub const fn new(modname: &'static CStr, name: &'stat= ic CStr) -> Self { } } =20 -// SAFETY: -// * `DeviceId` is a `#[repr(transparent)`] wrapper of `auxiliary_device_i= d` and does not add -// additional invariants, so it's safe to transmute to `RawType`. -// * `DRIVER_DATA_OFFSET` is the offset to the `driver_data` field. +// SAFETY: `DeviceId` is a `#[repr(transparent)]` wrapper of `auxiliary_de= vice_id` and does not add +// additional invariants, so it's safe to transmute to `RawType`. unsafe impl RawDeviceId for DeviceId { type RawType =3D bindings::auxiliary_device_id; +} =20 +// SAFETY: `DRIVER_DATA_OFFSET` is the offset to the `driver_data` field. +unsafe impl RawDeviceIdIndex for DeviceId { const DRIVER_DATA_OFFSET: usize =3D core::mem::offset_of!(bindings::auxiliary_device_id, driver_data); =20 diff --git a/rust/kernel/device_id.rs b/rust/kernel/device_id.rs index 3dc72ca8cfc2..242666c2409c 100644 --- a/rust/kernel/device_id.rs +++ b/rust/kernel/device_id.rs @@ -14,32 +14,41 @@ /// /// # Safety /// -/// Implementers must ensure that: -/// - `Self` is layout-compatible with [`RawDeviceId::RawType`]; i.e. it= 's safe to transmute to -/// `RawDeviceId`. +/// Implementers must ensure that `Self` is layout-compatible with [`RawDe= viceId::RawType`]; +/// i.e. it's safe to transmute to `RawDeviceId`. /// -/// This requirement is needed so `IdArray::new` can convert `Self` to= `RawType` when building -/// the ID table. +/// This requirement is needed so `IdArray::new` can convert `Self` to `Ra= wType` when building +/// the ID table. /// -/// Ideally, this should be achieved using a const function that does = conversion instead of -/// transmute; however, const trait functions relies on `const_trait_i= mpl` unstable feature, -/// which is broken/gone in Rust 1.73. -/// -/// - `DRIVER_DATA_OFFSET` is the offset of context/data field of the de= vice ID (usually named -/// `driver_data`) of the device ID, the field is suitable sized to wr= ite a `usize` value. -/// -/// Similar to the previous requirement, the data should ideally be ad= ded during `Self` to -/// `RawType` conversion, but there's currently no way to do it when u= sing traits in const. +/// Ideally, this should be achieved using a const function that does conv= ersion instead of +/// transmute; however, const trait functions relies on `const_trait_impl`= unstable feature, +/// which is broken/gone in Rust 1.73. pub unsafe trait RawDeviceId { /// The raw type that holds the device id. /// /// Id tables created from [`Self`] are going to hold this type in its= zero-terminated array. type RawType: Copy; +} =20 - /// The offset to the context/data field. +/// Extension trait for [`RawDeviceId`] for devices that embed an index or= context value. +/// +/// This is typically used when the device ID struct includes a field like= `driver_data` +/// that is used to store a pointer-sized value (e.g., an index or context= pointer). +/// +/// # Safety +/// +/// Implementers must ensure that `DRIVER_DATA_OFFSET` is the correct offs= et (in bytes) to +/// the context/data field (e.g., the `driver_data` field) within the raw = device ID structure. +/// This field must be correctly sized to hold a `usize`. +/// +/// Ideally, the data should be added during `Self` to `RawType` conversio= n, +/// but there's currently no way to do it when using traits in const. +pub unsafe trait RawDeviceIdIndex: RawDeviceId { + /// The offset (in bytes) to the context/data field in the raw device = ID. const DRIVER_DATA_OFFSET: usize; =20 - /// The index stored at `DRIVER_DATA_OFFSET` of the implementor of the= [`RawDeviceId`] trait. + /// The index stored at `DRIVER_DATA_OFFSET` of the implementor of the= [`RawDeviceIdIndex`] + /// trait. fn index(&self) -> usize; } =20 @@ -68,7 +77,14 @@ impl IdArray= { /// Creates a new instance of the array. /// /// The contents are derived from the given identifiers and context in= formation. - pub const fn new(ids: [(T, U); N]) -> Self { + /// + /// # Safety + /// + /// If `offset` is `Some(offset)`, then: + /// - `offset` must be the correct offset (in bytes) to the context/da= ta field + /// (e.g., the `driver_data` field) within the raw device ID structu= re. + /// - The field at `offset` must be correctly sized to hold a `usize`. + const unsafe fn build(ids: [(T, U); N], offset: Option) -> Self= { let mut raw_ids =3D [const { MaybeUninit::::uninit() }= ; N]; let mut infos =3D [const { MaybeUninit::uninit() }; N]; =20 @@ -77,14 +93,17 @@ impl IdArray { // SAFETY: by the safety requirement of `RawDeviceId`, we're g= uaranteed that `T` is // layout-wise compatible with `RawType`. raw_ids[i] =3D unsafe { core::mem::transmute_copy(&ids[i].0) }; - // SAFETY: by the safety requirement of `RawDeviceId`, this wo= uld be effectively - // `raw_ids[i].driver_data =3D i;`. - unsafe { - raw_ids[i] - .as_mut_ptr() - .byte_add(T::DRIVER_DATA_OFFSET) - .cast::() - .write(i); + + if let Some(offset) =3D offset { + // SAFETY: by the safety requirement of this function, thi= s would be effectively + // `raw_ids[i].driver_data =3D i;`. + unsafe { + raw_ids[i] + .as_mut_ptr() + .byte_add(offset) + .cast::() + .write(i); + } } =20 // SAFETY: this is effectively a move: `infos[i] =3D ids[i].1`= . We make a copy here but @@ -92,7 +111,6 @@ impl IdArray= { infos[i] =3D MaybeUninit::new(unsafe { core::ptr::read(&ids[i]= .1) }); i +=3D 1; } - core::mem::forget(ids); =20 Self { @@ -109,12 +127,33 @@ impl IdArray { } } =20 + /// Creates a new instance of the array without writing index values. + /// + /// The contents are derived from the given identifiers and context in= formation. + pub const fn new_without_index(ids: [(T, U); N]) -> Self { + // SAFETY: Calling `Self::build` with `offset =3D None` is always = safe, + // because no raw memory writes are performed in this case. + unsafe { Self::build(ids, None) } + } + /// Reference to the contained [`RawIdArray`]. pub const fn raw_ids(&self) -> &RawIdArray { &self.raw_ids } } =20 +impl IdArray { + /// Creates a new instance of the array. + /// + /// The contents are derived from the given identifiers and context in= formation. + pub const fn new(ids: [(T, U); N]) -> Self { + // SAFETY: by the safety requirement of `RawDeviceIdIndex`, + // `T::DRIVER_DATA_OFFSET` is guaranteed to be the correct offset = (in bytes) to + // a field within `T::RawType`. + unsafe { Self::build(ids, Some(T::DRIVER_DATA_OFFSET)) } + } +} + /// A device id table. /// /// This trait is only implemented by `IdArray`. diff --git a/rust/kernel/of.rs b/rust/kernel/of.rs index 40d1bd13682c..0c799a06371d 100644 --- a/rust/kernel/of.rs +++ b/rust/kernel/of.rs @@ -2,7 +2,11 @@ =20 //! Device Tree / Open Firmware abstractions. =20 -use crate::{bindings, device_id::RawDeviceId, prelude::*}; +use crate::{ + bindings, + device_id::{RawDeviceId, RawDeviceIdIndex}, + prelude::*, +}; =20 /// IdTable type for OF drivers. pub type IdTable =3D &'static dyn kernel::device_id::IdTable; @@ -12,13 +16,14 @@ #[derive(Clone, Copy)] pub struct DeviceId(bindings::of_device_id); =20 -// SAFETY: -// * `DeviceId` is a `#[repr(transparent)` wrapper of `struct of_device_id= ` and does not add -// additional invariants, so it's safe to transmute to `RawType`. -// * `DRIVER_DATA_OFFSET` is the offset to the `data` field. +// SAFETY: `DeviceId` is a `#[repr(transparent)]` wrapper of `struct of_de= vice_id` and does not add +// additional invariants, so it's safe to transmute to `RawType`. unsafe impl RawDeviceId for DeviceId { type RawType =3D bindings::of_device_id; +} =20 +// SAFETY: `DRIVER_DATA_OFFSET` is the offset to the `data` field. +unsafe impl RawDeviceIdIndex for DeviceId { const DRIVER_DATA_OFFSET: usize =3D core::mem::offset_of!(bindings::of= _device_id, data); =20 fn index(&self) -> usize { diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs index 6b94fd7a3ce9..8012bfad3150 100644 --- a/rust/kernel/pci.rs +++ b/rust/kernel/pci.rs @@ -7,7 +7,7 @@ use crate::{ alloc::flags::*, bindings, container_of, device, - device_id::RawDeviceId, + device_id::{RawDeviceId, RawDeviceIdIndex}, devres::Devres, driver, error::{to_result, Result}, @@ -161,13 +161,14 @@ pub const fn from_class(class: u32, class_mask: u32) = -> Self { } } =20 -// SAFETY: -// * `DeviceId` is a `#[repr(transparent)` wrapper of `pci_device_id` and = does not add -// additional invariants, so it's safe to transmute to `RawType`. -// * `DRIVER_DATA_OFFSET` is the offset to the `driver_data` field. +// SAFETY: `DeviceId` is a `#[repr(transparent)]` wrapper of `pci_device_i= d` and does not add +// additional invariants, so it's safe to transmute to `RawType`. unsafe impl RawDeviceId for DeviceId { type RawType =3D bindings::pci_device_id; +} =20 +// SAFETY: `DRIVER_DATA_OFFSET` is the offset to the `driver_data` field. +unsafe impl RawDeviceIdIndex for DeviceId { const DRIVER_DATA_OFFSET: usize =3D core::mem::offset_of!(bindings::pc= i_device_id, driver_data); =20 fn index(&self) -> usize { --=20 2.43.0