From patchwork Thu Dec 12 16:33:38 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Danilo Krummrich X-Patchwork-Id: 13905618 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 13FA5229683; Thu, 12 Dec 2024 16:35:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734021344; cv=none; b=LVqITObGHIvTkSH0u2sBxcqq441EqOB77IaRQK82B+R8yKF5A34M1r+I+EPLyoSubIDVzMnKU9u7vD+UC7ixU1FpPqABHWzNuZfHGI9yZ6rORw/WpPxGdodWupELo5ZuefMIh0ckuyB3oNmaFeXjHIQOoQtyEslupIGcUQe1HDA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734021344; c=relaxed/simple; bh=vWVnO7ZE6q2+LOY84TENtiGVXQ6BGkoTs0uxCm7MuHE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hAZWatvJUbhp9pSM2ZJ4obOv6aAr8rZcCbsC1592Kp2LzBPfVD5O4if446T7jZs0r1LtVL04mWn5zfWjH8lfroIrFmLxLLhIxvTysoaAefcJReKhggvHdTVbPVkJ12f0TQ6dYAda2sWwF4YG/brZExsbWgSuXKNnoqXSrB6/DDI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aMzkTbcB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aMzkTbcB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02D2DC4CED4; Thu, 12 Dec 2024 16:35:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734021343; bh=vWVnO7ZE6q2+LOY84TENtiGVXQ6BGkoTs0uxCm7MuHE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aMzkTbcB/7pMO3+e6rIIjika9wxMGeq9erVGX/8tEzmvPl1KYnsQHnlM9coKIcrVb blFycZQjto+9mlMfmy5v2B8FxIxDFoQWWYjHGT3B2FnA6qcAPX7uT6lEjZPdAujKDW /1Qp6ig0Sfn5SDJLor7dfvAEgYHslnTJmS5QfXyExTBiv2st7qDJ8SipjL9Xey2Ebk e0kbfm1AnnBd3b3n6SWlH7KLmxoTWhQn+3/CccF5yiM0TEkmBl+f09GD+hmf5mYAoF VoQyByH1qkux674yPVANdUxaf73GyGtI36iZQ8q9R/A/8Y4aKoMe+QvYMUsiWpK3vc ZXmrnoAaxZQ3A== From: Danilo Krummrich To: gregkh@linuxfoundation.org, rafael@kernel.org, bhelgaas@google.com, ojeda@kernel.org, alex.gaynor@gmail.com, boqun.feng@gmail.com, gary@garyguo.net, bjorn3_gh@protonmail.com, benno.lossin@proton.me, tmgross@umich.edu, a.hindborg@samsung.com, aliceryhl@google.com, airlied@gmail.com, fujita.tomonori@gmail.com, lina@asahilina.net, pstanner@redhat.com, ajanulgu@redhat.com, lyude@redhat.com, robh@kernel.org, daniel.almeida@collabora.com, saravanak@google.com, dirk.behme@de.bosch.com, j@jannau.net, fabien.parent@linaro.org, chrisi.schrefl@gmail.com, paulmck@kernel.org Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, devicetree@vger.kernel.org, rcu@vger.kernel.org, Danilo Krummrich Subject: [PATCH v6 07/16] rust: add `io::{Io, IoRaw}` base types Date: Thu, 12 Dec 2024 17:33:38 +0100 Message-ID: <20241212163357.35934-8-dakr@kernel.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241212163357.35934-1-dakr@kernel.org> References: <20241212163357.35934-1-dakr@kernel.org> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 I/O memory is typically either mapped through direct calls to ioremap() or subsystem / bus specific ones such as pci_iomap(). Even though subsystem / bus specific functions to map I/O memory are based on ioremap() / iounmap() it is not desirable to re-implement them in Rust. Instead, implement a base type for I/O mapped memory, which generically provides the corresponding accessors, such as `Io::readb` or `Io:try_readb`. `Io` supports an optional const generic, such that a driver can indicate the minimal expected and required size of the mapping at compile time. Correspondingly, calls to the 'non-try' accessors, support compile time checks of the I/O memory offset to read / write, while the 'try' accessors, provide boundary checks on runtime. `IoRaw` is meant to be embedded into a structure (e.g. pci::Bar or io::IoMem) which creates the actual I/O memory mapping and initializes `IoRaw` accordingly. To ensure that I/O mapped memory can't out-live the device it may be bound to, subsystems must embed the corresponding I/O memory type (e.g. pci::Bar) into a `Devres` container, such that it gets revoked once the device is unbound. Reviewed-by: Alice Ryhl Tested-by: Daniel Almeida Reviewed-by: Daniel Almeida Signed-off-by: Danilo Krummrich --- rust/helpers/helpers.c | 1 + rust/helpers/io.c | 101 ++++++++++++++++ rust/kernel/io.rs | 260 +++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 4 files changed, 363 insertions(+) create mode 100644 rust/helpers/io.c create mode 100644 rust/kernel/io.rs diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 060750af6524..63f9b1da179f 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -14,6 +14,7 @@ #include "cred.c" #include "err.c" #include "fs.c" +#include "io.c" #include "jump_label.c" #include "kunit.c" #include "mutex.c" diff --git a/rust/helpers/io.c b/rust/helpers/io.c new file mode 100644 index 000000000000..1dde6374c0e2 --- /dev/null +++ b/rust/helpers/io.c @@ -0,0 +1,101 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +void __iomem *rust_helper_ioremap(phys_addr_t offset, size_t size) +{ + return ioremap(offset, size); +} + +void rust_helper_iounmap(volatile void __iomem *addr) +{ + return iounmap(addr); +} + +u8 rust_helper_readb(const volatile void __iomem *addr) +{ + return readb(addr); +} + +u16 rust_helper_readw(const volatile void __iomem *addr) +{ + return readw(addr); +} + +u32 rust_helper_readl(const volatile void __iomem *addr) +{ + return readl(addr); +} + +#ifdef CONFIG_64BIT +u64 rust_helper_readq(const volatile void __iomem *addr) +{ + return readq(addr); +} +#endif + +void rust_helper_writeb(u8 value, volatile void __iomem *addr) +{ + writeb(value, addr); +} + +void rust_helper_writew(u16 value, volatile void __iomem *addr) +{ + writew(value, addr); +} + +void rust_helper_writel(u32 value, volatile void __iomem *addr) +{ + writel(value, addr); +} + +#ifdef CONFIG_64BIT +void rust_helper_writeq(u64 value, volatile void __iomem *addr) +{ + writeq(value, addr); +} +#endif + +u8 rust_helper_readb_relaxed(const volatile void __iomem *addr) +{ + return readb_relaxed(addr); +} + +u16 rust_helper_readw_relaxed(const volatile void __iomem *addr) +{ + return readw_relaxed(addr); +} + +u32 rust_helper_readl_relaxed(const volatile void __iomem *addr) +{ + return readl_relaxed(addr); +} + +#ifdef CONFIG_64BIT +u64 rust_helper_readq_relaxed(const volatile void __iomem *addr) +{ + return readq_relaxed(addr); +} +#endif + +void rust_helper_writeb_relaxed(u8 value, volatile void __iomem *addr) +{ + writeb_relaxed(value, addr); +} + +void rust_helper_writew_relaxed(u16 value, volatile void __iomem *addr) +{ + writew_relaxed(value, addr); +} + +void rust_helper_writel_relaxed(u32 value, volatile void __iomem *addr) +{ + writel_relaxed(value, addr); +} + +#ifdef CONFIG_64BIT +void rust_helper_writeq_relaxed(u64 value, volatile void __iomem *addr) +{ + writeq_relaxed(value, addr); +} +#endif diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs new file mode 100644 index 000000000000..7ec3341bb411 --- /dev/null +++ b/rust/kernel/io.rs @@ -0,0 +1,260 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Memory-mapped IO. +//! +//! C header: [`include/asm-generic/io.h`](srctree/include/asm-generic/io.h) + +use crate::error::{code::EINVAL, Result}; +use crate::{bindings, build_assert}; + +/// Raw representation of an MMIO region. +/// +/// By itself, the existence of an instance of this structure does not provide any guarantees that +/// the represented MMIO region does exist or is properly mapped. +/// +/// Instead, the bus specific MMIO implementation must convert this raw representation into an `Io` +/// instance providing the actual memory accessors. Only by the conversion into an `Io` structure +/// any guarantees are given. +pub struct IoRaw { + addr: usize, + maxsize: usize, +} + +impl IoRaw { + /// Returns a new `IoRaw` instance on success, an error otherwise. + pub fn new(addr: usize, maxsize: usize) -> Result { + if maxsize < SIZE { + return Err(EINVAL); + } + + Ok(Self { addr, maxsize }) + } + + /// Returns the base address of the MMIO region. + #[inline] + pub fn addr(&self) -> usize { + self.addr + } + + /// Returns the maximum size of the MMIO region. + #[inline] + pub fn maxsize(&self) -> usize { + self.maxsize + } +} + +/// IO-mapped memory, starting at the base address @addr and spanning @maxlen bytes. +/// +/// The creator (usually a subsystem / bus such as PCI) is responsible for creating the +/// mapping, performing an additional region request etc. +/// +/// # Invariant +/// +/// `addr` is the start and `maxsize` the length of valid I/O mapped memory region of size +/// `maxsize`. +/// +/// # Examples +/// +/// ```no_run +/// # use kernel::{bindings, io::{Io, IoRaw}}; +/// # use core::ops::Deref; +/// +/// // See also [`pci::Bar`] for a real example. +/// struct IoMem(IoRaw); +/// +/// impl IoMem { +/// /// # Safety +/// /// +/// /// [`paddr`, `paddr` + `SIZE`) must be a valid MMIO region that is mappable into the CPUs +/// /// virtual address space. +/// unsafe fn new(paddr: usize) -> Result{ +/// // SAFETY: By the safety requirements of this function [`paddr`, `paddr` + `SIZE`) is +/// // valid for `ioremap`. +/// let addr = unsafe { bindings::ioremap(paddr as _, SIZE.try_into().unwrap()) }; +/// if addr.is_null() { +/// return Err(ENOMEM); +/// } +/// +/// Ok(IoMem(IoRaw::new(addr as _, SIZE)?)) +/// } +/// } +/// +/// impl Drop for IoMem { +/// fn drop(&mut self) { +/// // SAFETY: `self.0.addr()` is guaranteed to be properly mapped by `Self::new`. +/// unsafe { bindings::iounmap(self.0.addr() as _); }; +/// } +/// } +/// +/// impl Deref for IoMem { +/// type Target = Io; +/// +/// fn deref(&self) -> &Self::Target { +/// // SAFETY: The memory range stored in `self` has been properly mapped in `Self::new`. +/// unsafe { Io::from_raw(&self.0) } +/// } +/// } +/// +///# fn no_run() -> Result<(), Error> { +/// // SAFETY: Invalid usage for example purposes. +/// let iomem = unsafe { IoMem::<{ core::mem::size_of::() }>::new(0xBAAAAAAD)? }; +/// iomem.writel(0x42, 0x0); +/// assert!(iomem.try_writel(0x42, 0x0).is_ok()); +/// assert!(iomem.try_writel(0x42, 0x4).is_err()); +/// # Ok(()) +/// # } +/// ``` +#[repr(transparent)] +pub struct Io(IoRaw); + +macro_rules! define_read { + ($(#[$attr:meta])* $name:ident, $try_name:ident, $type_name:ty) => { + /// Read IO data from a given offset known at compile time. + /// + /// Bound checks are performed on compile time, hence if the offset is not known at compile + /// time, the build will fail. + $(#[$attr])* + #[inline] + pub fn $name(&self, offset: usize) -> $type_name { + let addr = self.io_addr_assert::<$type_name>(offset); + + // SAFETY: By the type invariant `addr` is a valid address for MMIO operations. + unsafe { bindings::$name(addr as _) } + } + + /// Read IO data from a given offset. + /// + /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is + /// out of bounds. + $(#[$attr])* + pub fn $try_name(&self, offset: usize) -> Result<$type_name> { + let addr = self.io_addr::<$type_name>(offset)?; + + // SAFETY: By the type invariant `addr` is a valid address for MMIO operations. + Ok(unsafe { bindings::$name(addr as _) }) + } + }; +} + +macro_rules! define_write { + ($(#[$attr:meta])* $name:ident, $try_name:ident, $type_name:ty) => { + /// Write IO data from a given offset known at compile time. + /// + /// Bound checks are performed on compile time, hence if the offset is not known at compile + /// time, the build will fail. + $(#[$attr])* + #[inline] + pub fn $name(&self, value: $type_name, offset: usize) { + let addr = self.io_addr_assert::<$type_name>(offset); + + // SAFETY: By the type invariant `addr` is a valid address for MMIO operations. + unsafe { bindings::$name(value, addr as _, ) } + } + + /// Write IO data from a given offset. + /// + /// Bound checks are performed on runtime, it fails if the offset (plus the type size) is + /// out of bounds. + $(#[$attr])* + pub fn $try_name(&self, value: $type_name, offset: usize) -> Result { + let addr = self.io_addr::<$type_name>(offset)?; + + // SAFETY: By the type invariant `addr` is a valid address for MMIO operations. + unsafe { bindings::$name(value, addr as _) } + Ok(()) + } + }; +} + +impl Io { + /// Converts an `IoRaw` into an `Io` instance, providing the accessors to the MMIO mapping. + /// + /// # Safety + /// + /// Callers must ensure that `addr` is the start of a valid I/O mapped memory region of size + /// `maxsize`. + pub unsafe fn from_raw(raw: &IoRaw) -> &Self { + // SAFETY: `Io` is a transparent wrapper around `IoRaw`. + unsafe { &*core::ptr::from_ref(raw).cast() } + } + + /// Returns the base address of this mapping. + #[inline] + pub fn addr(&self) -> usize { + self.0.addr() + } + + /// Returns the maximum size of this mapping. + #[inline] + pub fn maxsize(&self) -> usize { + self.0.maxsize() + } + + #[inline] + const fn offset_valid(offset: usize, size: usize) -> bool { + let type_size = core::mem::size_of::(); + if let Some(end) = offset.checked_add(type_size) { + end <= size && offset % type_size == 0 + } else { + false + } + } + + #[inline] + fn io_addr(&self, offset: usize) -> Result { + if !Self::offset_valid::(offset, self.maxsize()) { + return Err(EINVAL); + } + + // Probably no need to check, since the safety requirements of `Self::new` guarantee that + // this can't overflow. + self.addr().checked_add(offset).ok_or(EINVAL) + } + + #[inline] + fn io_addr_assert(&self, offset: usize) -> usize { + build_assert!(Self::offset_valid::(offset, SIZE)); + + self.addr() + offset + } + + define_read!(readb, try_readb, u8); + define_read!(readw, try_readw, u16); + define_read!(readl, try_readl, u32); + define_read!( + #[cfg(CONFIG_64BIT)] + readq, + try_readq, + u64 + ); + + define_read!(readb_relaxed, try_readb_relaxed, u8); + define_read!(readw_relaxed, try_readw_relaxed, u16); + define_read!(readl_relaxed, try_readl_relaxed, u32); + define_read!( + #[cfg(CONFIG_64BIT)] + readq_relaxed, + try_readq_relaxed, + u64 + ); + + define_write!(writeb, try_writeb, u8); + define_write!(writew, try_writew, u16); + define_write!(writel, try_writel, u32); + define_write!( + #[cfg(CONFIG_64BIT)] + writeq, + try_writeq, + u64 + ); + + define_write!(writeb_relaxed, try_writeb_relaxed, u8); + define_write!(writew_relaxed, try_writew_relaxed, u16); + define_write!(writel_relaxed, try_writel_relaxed, u32); + define_write!( + #[cfg(CONFIG_64BIT)] + writeq_relaxed, + try_writeq_relaxed, + u64 + ); +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 5702ce32ec8e..6c836ab73771 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -79,6 +79,7 @@ #[doc(hidden)] pub use bindings; +pub mod io; pub use macros; pub use uapi;