github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-22 12:44:03 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

rust: io: use view types instead of addresses for Io

Browse Source 
Currently, `io_read` and `io_write` methods require the exact type of `Io`
plus an address. This means that they need to be monomorphized for each
different `Io` instance. This also means that multiple I/O implementors for
the same I/O kind needs to duplicate implementation (e.g. `Mmio` and
`MmioOwned`).

Create a new `IoBackend` trait and define these operations on it instead.
The operations are just going to receive a view type and operate on them.
This has the additional advantage that the invariants can be moved from the
trait (and guaranteed via `unsafe`) to type invariants on the canonical
view types of the backends, so `io_read` and `io_write` can be safe.

Note that a view type is needed; addresses are insufficient in this
design, as they do not carry sufficient information. For example,
`ConfigSpace` needs `&pci::Device` in addition to the address.

`io_addr_assert` and `io_addr` are renamed to `io_view*` to reflect
that they operate on views now, and make them standalone functions so
they cannot be used by users to cast types outside io.rs.

Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com>
Link: https://patch.msgid.link/20260706-io_projection-v6-9-72cd5d055d54@garyguo.net
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This commit is contained in:
Gary Guo 2026-07-06 13:44:22 +01:00 committed by Danilo Krummrich
parent 6e5f28968d
commit e0454ec122
2 changed files with 249 additions and 209 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

388
rust/kernel/io.rs
View File

@ -244,6 +244,81 @@ const fn offset_valid<U>(base: usize, offset: usize, size: usize) -> bool {
}
}
/// Returns a view for a given `offset`, performing compile-time bound checks.
// Always inline to optimize out error path of `build_assert`.
#[inline(always)]
fn io_view_assert<'a, IO: Io<'a>, U>(
this: IO,
offset: usize,
) -> <IO::Backend as IoBackend>::View<'a, U> {
// We cannot check alignment with `offset_valid` using `ptr.addr()`. So set 0 for it and
// ensure alignment by checking that the alignment of `U` is smaller or equal to the
// alignment of `IO::Target`.
const_assert!(Alignment::of::<U>().as_usize() <= IO::Target::MIN_ALIGN.as_usize());
build_assert!(offset_valid::<U>(0, offset, IO::Target::MIN_SIZE));
let view = this.as_view();
let ptr = IO::Backend::as_ptr(view);
let projected_ptr = ptr.cast::<U>().wrapping_byte_add(offset);
// SAFETY: `offset_valid` checks for size and alignment and therefore `projected_ptr` is a
// valid projection.
unsafe { IO::Backend::project_view(view, projected_ptr) }
}
/// Returns a view for a given `offset`, performing runtime bound checks.
#[inline]
fn io_view<'a, IO: Io<'a>, U>(
this: IO,
offset: usize,
) -> Result<<IO::Backend as IoBackend>::View<'a, U>> {
let view = this.as_view();
let ptr = IO::Backend::as_ptr(view);
if !offset_valid::<U>(ptr.addr(), offset, KnownSize::size(ptr)) {
return Err(EINVAL);
}
let projected_ptr = ptr.cast::<U>().wrapping_byte_add(offset);
// SAFETY: `offset_valid` checks for size and alignment and therefore `projected_ptr` is a
// valid projection.
Ok(unsafe { IO::Backend::project_view(view, projected_ptr) })
}
/// I/O backends.
///
/// This is an abstract representation to be implemented by arbitrary I/O
/// backends (e.g. MMIO, PCI config space, etc.).
///
/// The base trait only defines the projection operations; which I/O methods are available depends
/// on which [`IoCapable<T>`] traits are implemented for the type. For example, for MMIO regions,
/// all widths (u8, u16, u32, and u64 on 64-bit systems) are typically supported. For PCI
/// configuration space, u8, u16, and u32 are supported but u64 is not.
///
/// This trait is separate from the `Io` trait as multiple different I/O types may share the same
/// operation.
pub trait IoBackend {
/// View type for this I/O backend.
type View<'a, T: ?Sized + KnownSize>: Io<'a, Backend = Self, Target = T>;
/// Convert a `view` to a raw pointer for projection.
///
/// The returned pointer is private implementation detail of the backend; it is likely not
/// valid. It should not be dereferenced.
fn as_ptr<'a, T: ?Sized + KnownSize>(view: Self::View<'a, T>) -> *mut T;
/// Project `view` to its subregion indicated by `ptr`.
///
/// If input `view` is valid, returned view must also be valid.
///
/// # Safety
///
/// `ptr` must be a projection of `Self::as_ptr(view)`.
unsafe fn project_view<'a, T: ?Sized + KnownSize, U: ?Sized + KnownSize>(
view: Self::View<'a, T>,
ptr: *mut U,
) -> Self::View<'a, U>;
}
/// Trait indicating that an I/O backend supports operations of a certain type and providing an
/// implementation for these operations.
///
@ -252,22 +327,12 @@ const fn offset_valid<U>(base: usize, offset: usize, size: usize) -> bool {
/// For example, a PCI configuration space may implement `IoCapable<u8>`, `IoCapable<u16>`,
/// and `IoCapable<u32>`, but not `IoCapable<u64>`, while an MMIO region on a 64-bit
/// system might implement all four.
pub trait IoCapable<T> {
/// Performs an I/O read of type `T` at `address` and returns the result.
///
/// # Safety
///
/// - The range `[address..address + size_of::<T>()]` must be within the bounds of `Self`.
/// - `address` must be aligned.
unsafe fn io_read(self, address: usize) -> T;
pub trait IoCapable<T>: IoBackend {
/// Performs an I/O read of type `T` at `view` and returns the result.
fn io_read<'a>(view: Self::View<'a, T>) -> T;
/// Performs an I/O write of `value` at `address`.
///
/// # Safety
///
/// - The range `[address..address + size_of::<T>()]` must be within the bounds of `Self`.
/// - `address` must be aligned.
unsafe fn io_write(self, value: T, address: usize);
/// Performs an I/O write of `value` at `view`.
fn io_write<'a>(view: Self::View<'a, T>, value: T);
}
/// Describes a given I/O location: its offset, width, and type to convert the raw value from and
@ -319,66 +384,30 @@ fn offset(self) -> usize {
/// Types implementing this trait (e.g. MMIO BARs or PCI config regions)
/// can perform I/O operations on regions of memory.
///
/// This is an abstract representation to be implemented by arbitrary I/O
/// backends (e.g. MMIO, PCI config space, etc.).
///
/// The [`Io`] trait provides:
/// - Base address and size information
/// - Method to convert into [`IoBackend::View`].
/// - Helper methods for offset validation and address calculation
/// - Fallible (runtime checked) accessors for different data widths
///
/// Which I/O methods are available depends on which [`IoCapable<T>`] traits
/// are implemented for the type.
/// Which I/O methods are available depends on the associated [`IoBackend`] implementation.
///
/// This should be implemented on cheaply copyable handles, such as references or view types.
///
/// # Examples
///
/// For MMIO regions, all widths (u8, u16, u32, and u64 on 64-bit systems) are typically
/// supported. For PCI configuration space, u8, u16, and u32 are supported but u64 is not.
pub trait Io: Copy {
pub trait Io<'a>: Copy {
/// Type that defines all I/O operations.
type Backend: IoBackend;
/// Type of this I/O region. For untyped regions, [`Region`] can be used.
type Target: ?Sized + KnownSize;
/// Returns the base address of this mapping.
fn addr(self) -> usize;
/// Returns the maximum size of this mapping.
fn maxsize(self) -> usize;
/// Returns the absolute I/O address for a given `offset`,
/// performing compile-time bound checks.
// Always inline to optimize out error path of `build_assert`.
#[inline(always)]
fn io_addr_assert<U>(self, offset: usize) -> usize {
// We cannot check alignment with `offset_valid` using `self.addr()`. So set 0 for it and
// ensure alignment by checking that the alignment of `U` is smaller or equal to the
// alignment of `Self::Target`.
const_assert!(Alignment::of::<U>().as_usize() <= Self::Target::MIN_ALIGN.as_usize());
build_assert!(offset_valid::<U>(0, offset, Self::Target::MIN_SIZE));
self.addr() + offset
}
/// Returns the absolute I/O address for a given `offset`,
/// performing runtime bound checks.
#[inline]
fn io_addr<U>(self, offset: usize) -> Result<usize> {
if !offset_valid::<U>(self.addr(), 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)
}
/// Return a view that covers the full region.
fn as_view(self) -> <Self::Backend as IoBackend>::View<'a, Self::Target>;
/// Fallible 8-bit read with runtime bounds check.
#[inline(always)]
fn try_read8(self, offset: usize) -> Result<u8>
where
usize: IoLoc<Self::Target, u8, IoType = u8>,
Self: IoCapable<u8>,
Self::Backend: IoCapable<u8>,
{
self.try_read(offset)
}
@ -388,7 +417,7 @@ fn try_read8(self, offset: usize) -> Result<u8>
fn try_read16(self, offset: usize) -> Result<u16>
where
usize: IoLoc<Self::Target, u16, IoType = u16>,
Self: IoCapable<u16>,
Self::Backend: IoCapable<u16>,
{
self.try_read(offset)
}
@ -398,7 +427,7 @@ fn try_read16(self, offset: usize) -> Result<u16>
fn try_read32(self, offset: usize) -> Result<u32>
where
usize: IoLoc<Self::Target, u32, IoType = u32>,
Self: IoCapable<u32>,
Self::Backend: IoCapable<u32>,
{
self.try_read(offset)
}
@ -408,7 +437,7 @@ fn try_read32(self, offset: usize) -> Result<u32>
fn try_read64(self, offset: usize) -> Result<u64>
where
usize: IoLoc<Self::Target, u64, IoType = u64>,
Self: IoCapable<u64>,
Self::Backend: IoCapable<u64>,
{
self.try_read(offset)
}
@ -418,7 +447,7 @@ fn try_read64(self, offset: usize) -> Result<u64>
fn try_write8(self, value: u8, offset: usize) -> Result
where
usize: IoLoc<Self::Target, u8, IoType = u8>,
Self: IoCapable<u8>,
Self::Backend: IoCapable<u8>,
{
self.try_write(offset, value)
}
@ -428,7 +457,7 @@ fn try_write8(self, value: u8, offset: usize) -> Result
fn try_write16(self, value: u16, offset: usize) -> Result
where
usize: IoLoc<Self::Target, u16, IoType = u16>,
Self: IoCapable<u16>,
Self::Backend: IoCapable<u16>,
{
self.try_write(offset, value)
}
@ -438,7 +467,7 @@ fn try_write16(self, value: u16, offset: usize) -> Result
fn try_write32(self, value: u32, offset: usize) -> Result
where
usize: IoLoc<Self::Target, u32, IoType = u32>,
Self: IoCapable<u32>,
Self::Backend: IoCapable<u32>,
{
self.try_write(offset, value)
}
@ -448,7 +477,7 @@ fn try_write32(self, value: u32, offset: usize) -> Result
fn try_write64(self, value: u64, offset: usize) -> Result
where
usize: IoLoc<Self::Target, u64, IoType = u64>,
Self: IoCapable<u64>,
Self::Backend: IoCapable<u64>,
{
self.try_write(offset, value)
}
@ -458,7 +487,7 @@ fn try_write64(self, value: u64, offset: usize) -> Result
fn read8(self, offset: usize) -> u8
where
usize: IoLoc<Self::Target, u8, IoType = u8>,
Self: IoCapable<u8>,
Self::Backend: IoCapable<u8>,
{
self.read(offset)
}
@ -468,7 +497,7 @@ fn read8(self, offset: usize) -> u8
fn read16(self, offset: usize) -> u16
where
usize: IoLoc<Self::Target, u16, IoType = u16>,
Self: IoCapable<u16>,
Self::Backend: IoCapable<u16>,
{
self.read(offset)
}
@ -478,7 +507,7 @@ fn read16(self, offset: usize) -> u16
fn read32(self, offset: usize) -> u32
where
usize: IoLoc<Self::Target, u32, IoType = u32>,
Self: IoCapable<u32>,
Self::Backend: IoCapable<u32>,
{
self.read(offset)
}
@ -488,7 +517,7 @@ fn read32(self, offset: usize) -> u32
fn read64(self, offset: usize) -> u64
where
usize: IoLoc<Self::Target, u64, IoType = u64>,
Self: IoCapable<u64>,
Self::Backend: IoCapable<u64>,
{
self.read(offset)
}
@ -498,7 +527,7 @@ fn read64(self, offset: usize) -> u64
fn write8(self, value: u8, offset: usize)
where
usize: IoLoc<Self::Target, u8, IoType = u8>,
Self: IoCapable<u8>,
Self::Backend: IoCapable<u8>,
{
self.write(offset, value)
}
@ -508,7 +537,7 @@ fn write8(self, value: u8, offset: usize)
fn write16(self, value: u16, offset: usize)
where
usize: IoLoc<Self::Target, u16, IoType = u16>,
Self: IoCapable<u16>,
Self::Backend: IoCapable<u16>,
{
self.write(offset, value)
}
@ -518,7 +547,7 @@ fn write16(self, value: u16, offset: usize)
fn write32(self, value: u32, offset: usize)
where
usize: IoLoc<Self::Target, u32, IoType = u32>,
Self: IoCapable<u32>,
Self::Backend: IoCapable<u32>,
{
self.write(offset, value)
}
@ -528,7 +557,7 @@ fn write32(self, value: u32, offset: usize)
fn write64(self, value: u64, offset: usize)
where
usize: IoLoc<Self::Target, u64, IoType = u64>,
Self: IoCapable<u64>,
Self::Backend: IoCapable<u64>,
{
self.write(offset, value)
}
@ -560,12 +589,10 @@ fn write64(self, value: u64, offset: usize)
fn try_read<T, L>(self, location: L) -> Result<T>
where
L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
Self::Backend: IoCapable<L::IoType>,
{
let address = self.io_addr::<L::IoType>(location.offset())?;
// SAFETY: `address` has been validated by `io_addr`.
Ok(unsafe { self.io_read(address) }.into())
let view = io_view::<Self, L::IoType>(self, location.offset())?;
Ok(Self::Backend::io_read(view).into())
}
/// Generic fallible write with runtime bounds check.
@ -595,14 +622,11 @@ fn try_read<T, L>(self, location: L) -> Result<T>
fn try_write<T, L>(self, location: L, value: T) -> Result
where
L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
Self::Backend: IoCapable<L::IoType>,
{
let address = self.io_addr::<L::IoType>(location.offset())?;
let view = io_view::<Self, L::IoType>(self, location.offset())?;
let io_value = value.into();
// SAFETY: `address` has been validated by `io_addr`.
unsafe { self.io_write(io_value, address) }
Self::Backend::io_write(view, io_value);
Ok(())
}
@ -643,7 +667,7 @@ fn try_write_reg<T, L, V>(self, value: V) -> Result
where
L: IoLoc<Self::Target, T>,
V: LocatedRegister<Self::Target, Location = L, Value = T>,
Self: IoCapable<L::IoType>,
Self::Backend: IoCapable<L::IoType>,
{
let (location, value) = value.into_io_op();
@ -676,17 +700,14 @@ fn try_write_reg<T, L, V>(self, value: V) -> Result
fn try_update<T, L, F>(self, location: L, f: F) -> Result
where
L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
Self::Backend: IoCapable<L::IoType>,
F: FnOnce(T) -> T,
{
let address = self.io_addr::<L::IoType>(location.offset())?;
let view = io_view::<Self, L::IoType>(self, location.offset())?;
// SAFETY: `address` has been validated by `io_addr`.
let value: T = unsafe { self.io_read(address) }.into();
let value: T = Self::Backend::io_read(view).into();
let io_value = f(value).into();
// SAFETY: `address` has been validated by `io_addr`.
unsafe { self.io_write(io_value, address) }
Self::Backend::io_write(view, io_value);
Ok(())
}
@ -716,12 +737,10 @@ fn try_update<T, L, F>(self, location: L, f: F) -> Result
fn read<T, L>(self, location: L) -> T
where
L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
Self::Backend: IoCapable<L::IoType>,
{
let address = self.io_addr_assert::<L::IoType>(location.offset());
// SAFETY: `address` has been validated by `io_addr_assert`.
unsafe { self.io_read(address) }.into()
let view = io_view_assert::<Self, L::IoType>(self, location.offset());
Self::Backend::io_read(view).into()
}
/// Generic infallible write with compile-time bounds check.
@ -749,13 +768,11 @@ fn read<T, L>(self, location: L) -> T
fn write<T, L>(self, location: L, value: T)
where
L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
Self::Backend: IoCapable<L::IoType>,
{
let address = self.io_addr_assert::<L::IoType>(location.offset());
let view = io_view_assert::<Self, L::IoType>(self, location.offset());
let io_value = value.into();
// SAFETY: `address` has been validated by `io_addr_assert`.
unsafe { self.io_write(io_value, address) }
Self::Backend::io_write(view, io_value);
}
/// Generic infallible write of a fully-located register value.
@ -794,7 +811,7 @@ fn write_reg<T, L, V>(self, value: V)
where
L: IoLoc<Self::Target, T>,
V: LocatedRegister<Self::Target, Location = L, Value = T>,
Self: IoCapable<L::IoType>,
Self::Backend: IoCapable<L::IoType>,
{
let (location, value) = value.into_io_op();
@ -827,17 +844,13 @@ fn write_reg<T, L, V>(self, value: V)
fn update<T, L, F>(self, location: L, f: F)
where
L: IoLoc<Self::Target, T>,
Self: IoCapable<L::IoType>,
Self::Backend: IoCapable<L::IoType>,
F: FnOnce(T) -> T,
{
let address = self.io_addr_assert::<L::IoType>(location.offset());
// SAFETY: `address` has been validated by `io_addr_assert`.
let value: T = unsafe { self.io_read(address) }.into();
let view = io_view_assert::<Self, L::IoType>(self, location.offset());
let value: T = Self::Backend::io_read(view).into();
let io_value = f(value).into();
// SAFETY: `address` has been validated by `io_addr_assert`.
unsafe { self.io_write(io_value, address) }
Self::Backend::io_write(view, io_value);
}
}
@ -881,78 +894,78 @@ unsafe impl<T: ?Sized + Sync> Send for Mmio<'_, T> {}
// SAFETY: `Mmio<'_, T>` is conceptually `&T` but in I/O memory.
unsafe impl<T: ?Sized + Sync> Sync for Mmio<'_, T> {}
impl<T: ?Sized + KnownSize> Io for Mmio<'_, T> {
impl<'a, T: ?Sized + KnownSize> Io<'a> for Mmio<'a, T> {
type Backend = MmioBackend;
type Target = T;
#[inline]
fn addr(self) -> usize {
self.ptr.addr()
}
#[inline]
fn maxsize(self) -> usize {
KnownSize::size(self.ptr)
fn as_view(self) -> Mmio<'a, T> {
self
}
}
/// Implements [`IoCapable`] on `$mmio` for `$ty` using `$read_fn` and `$write_fn`.
/// I/O Backend for memory-mapped I/O.
pub struct MmioBackend;
impl IoBackend for MmioBackend {
type View<'a, T: ?Sized + KnownSize> = Mmio<'a, T>;
#[inline]
fn as_ptr<'a, T: ?Sized + KnownSize>(view: Self::View<'a, T>) -> *mut T {
view.ptr
}
#[inline]
unsafe fn project_view<'a, T: ?Sized + KnownSize, U: ?Sized + KnownSize>(
_view: Self::View<'a, T>,
ptr: *mut U,
) -> Self::View<'a, U> {
// INVARIANT: Per safety requirement, `ptr` is projection from `view`, so it is also a valid
// memory-mapped I/O region.
Mmio {
ptr,
phantom: PhantomData,
}
}
}
/// Implements [`IoCapable`] on `$backend` for `$ty` using `$read_fn` and `$write_fn`.
macro_rules! impl_mmio_io_capable {
($mmio:ident, $(#[$attr:meta])* $ty:ty, $read_fn:ident, $write_fn:ident) => {
$(#[$attr])*
impl<T: ?Sized> IoCapable<$ty> for $mmio<'_, T> {
($backend: ident, $ty:ty, $read_fn:ident, $write_fn:ident) => {
impl IoCapable<$ty> for $backend {
#[inline]
unsafe fn io_read(self, address: usize) -> $ty {
// SAFETY: By the trait invariant `address` is a valid address for MMIO operations.
unsafe { bindings::$read_fn(address as *const c_void) }
fn io_read(view: <$backend as IoBackend>::View<'_, $ty>) -> $ty {
// SAFETY: `$backend::as_ptr(view)` is a valid pointer for MMIO operations for both
// `MmioBackend` and `RelaxedMmioBackend`.
unsafe { bindings::$read_fn($backend::as_ptr(view).cast_const().cast()) }
}
#[inline]
unsafe fn io_write(self, value: $ty, address: usize) {
// SAFETY: By the trait invariant `address` is a valid address for MMIO operations.
unsafe { bindings::$write_fn(value, address as *mut c_void) }
fn io_write(view: <$backend as IoBackend>::View<'_, $ty>, value: $ty) {
// SAFETY: `$backend::as_ptr(view)` is a valid pointer for MMIO operations for both
// `MmioBackend` and `RelaxedMmioBackend`.
unsafe { bindings::$write_fn(value, $backend::as_ptr(view).cast()) }
}
}
};
}
// MMIO regions support 8, 16, and 32-bit accesses.
impl_mmio_io_capable!(Mmio, u8, readb, writeb);
impl_mmio_io_capable!(Mmio, u16, readw, writew);
impl_mmio_io_capable!(Mmio, u32, readl, writel);
impl_mmio_io_capable!(MmioBackend, u8, readb, writeb);
impl_mmio_io_capable!(MmioBackend, u16, readw, writew);
impl_mmio_io_capable!(MmioBackend, u32, readl, writel);
// MMIO regions on 64-bit systems also support 64-bit accesses.
#[cfg(CONFIG_64BIT)]
impl_mmio_io_capable!(Mmio, u64, readq, writeq);
impl_mmio_io_capable!(MmioBackend, u64, readq, writeq);
impl<'a, const SIZE: usize> Io for &'a MmioOwned<SIZE> {
impl<'a, const SIZE: usize> Io<'a> for &'a MmioOwned<SIZE> {
type Backend = MmioBackend;
type Target = Region<SIZE>;
/// Returns the base address of this mapping.
#[inline]
fn addr(self) -> usize {
self.0.addr()
}
/// Returns the maximum size of this mapping.
#[inline]
fn maxsize(self) -> usize {
self.0.size()
}
}
impl<'a, const SIZE: usize, T> IoCapable<T> for &'a MmioOwned<SIZE>
where
Mmio<'a, Region<SIZE>>: IoCapable<T>,
{
#[inline]
unsafe fn io_read(self, address: usize) -> T {
// SAFETY: Per safety requirement.
unsafe { self.as_view().io_read(address) }
}
#[inline]
unsafe fn io_write(self, value: T, address: usize) {
// SAFETY: Per safety requirement.
unsafe { self.as_view().io_write(value, address) }
fn as_view(self) -> Mmio<'a, Self::Target> {
// SAFETY: `Mmio` has same invariant as `MmioOwned`
unsafe { Mmio::from_raw(self.0) }
}
}
@ -968,13 +981,6 @@ pub unsafe fn from_raw(raw: &MmioRaw<Region<SIZE>>) -> &Self {
// SAFETY: `MmioOwned` is a transparent wrapper around `MmioRaw`.
unsafe { &*core::ptr::from_ref(raw).cast() }
}
/// Return a view that covers the full region.
#[inline]
pub fn as_view(&self) -> Mmio<'_, Region<SIZE>> {
// SAFETY: `Mmio` has same invariant as `MmioOwned`.
unsafe { Mmio::from_raw(self.0) }
}
}
/// [`Mmio`] but using relaxed accessors.
@ -993,17 +999,34 @@ fn clone(&self) -> Self {
}
}
impl<T: ?Sized + KnownSize> Io for RelaxedMmio<'_, T> {
type Target = T;
/// I/O Backend for memory-mapped I/O, with relaxed access semantics.
pub struct RelaxedMmioBackend;
impl IoBackend for RelaxedMmioBackend {
type View<'a, T: ?Sized + KnownSize> = RelaxedMmio<'a, T>;
#[inline]
fn addr(self) -> usize {
self.0.addr()
fn as_ptr<'a, T: ?Sized + KnownSize>(view: Self::View<'a, T>) -> *mut T {
MmioBackend::as_ptr(view.0)
}
#[inline]
fn maxsize(self) -> usize {
self.0.maxsize()
unsafe fn project_view<'a, T: ?Sized + KnownSize, U: ?Sized + KnownSize>(
view: Self::View<'a, T>,
ptr: *mut U,
) -> Self::View<'a, U> {
// SAFETY: Per safety requirement.
RelaxedMmio(unsafe { MmioBackend::project_view(view.0, ptr) })
}
}
impl<'a, T: ?Sized + KnownSize> Io<'a> for RelaxedMmio<'a, T> {
type Backend = RelaxedMmioBackend;
type Target = T;
#[inline]
fn as_view(self) -> RelaxedMmio<'a, T> {
self
}
}
@ -1036,14 +1059,9 @@ pub fn relaxed(self) -> RelaxedMmio<'a, T> {
}
// MMIO regions support 8, 16, and 32-bit accesses.
impl_mmio_io_capable!(RelaxedMmio, u8, readb_relaxed, writeb_relaxed);
impl_mmio_io_capable!(RelaxedMmio, u16, readw_relaxed, writew_relaxed);
impl_mmio_io_capable!(RelaxedMmio, u32, readl_relaxed, writel_relaxed);
impl_mmio_io_capable!(RelaxedMmioBackend, u8, readb_relaxed, writeb_relaxed);
impl_mmio_io_capable!(RelaxedMmioBackend, u16, readw_relaxed, writew_relaxed);
impl_mmio_io_capable!(RelaxedMmioBackend, u32, readl_relaxed, writel_relaxed);
// MMIO regions on 64-bit systems also support 64-bit accesses.
impl_mmio_io_capable!(
RelaxedMmio,
#[cfg(CONFIG_64BIT)]
u64,
readq_relaxed,
writeq_relaxed
);
#[cfg(CONFIG_64BIT)]
impl_mmio_io_capable!(RelaxedMmioBackend, u64, readq_relaxed, writeq_relaxed);

70
rust/kernel/pci/io.rs
View File

@ -9,6 +9,7 @@
devres::Devres,
io::{
Io,
IoBackend,
IoCapable,
MmioOwned,
MmioRaw,
@ -84,32 +85,57 @@ unsafe impl<T: ?Sized + Sync> Send for ConfigSpace<'_, T> {}
// SAFETY: `ConfigSpace<'_, T>` is conceptually `&T` but in I/O memory.
unsafe impl<T: ?Sized + Sync> Sync for ConfigSpace<'_, T> {}
/// I/O Backend for PCI configuration space.
pub struct ConfigSpaceBackend;
impl IoBackend for ConfigSpaceBackend {
type View<'a, T: ?Sized + KnownSize> = ConfigSpace<'a, T>;
#[inline]
fn as_ptr<'a, T: ?Sized + KnownSize>(view: ConfigSpace<'a, T>) -> *mut T {
view.ptr
}
#[inline]
unsafe fn project_view<'a, T: ?Sized + KnownSize, U: ?Sized + KnownSize>(
view: Self::View<'a, T>,
ptr: *mut U,
) -> Self::View<'a, U> {
// INVARIANT: Per safety requirement.
ConfigSpace {
pdev: view.pdev,
ptr,
}
}
}
/// Implements [`IoCapable`] on [`ConfigSpace`] for `$ty` using `$read_fn` and `$write_fn`.
macro_rules! impl_config_space_io_capable {
($ty:ty, $read_fn:ident, $write_fn:ident) => {
impl<'a, T: ?Sized> IoCapable<$ty> for ConfigSpace<'a, T> {
unsafe fn io_read(self, address: usize) -> $ty {
impl IoCapable<$ty> for ConfigSpaceBackend {
fn io_read(view: ConfigSpace<'_, $ty>) -> $ty {
// CAST: The offset is cast to `i32` because the C functions expect a 32-bit
// signed offset parameter. PCI configuration space size is at most 4096 bytes,
// so the value always fits within `i32` without truncation or sign change.
let addr = view.ptr.addr() as i32;
let mut val: $ty = 0;
// Return value from C function is ignored in infallible accessors.
let _ret =
// SAFETY: By the type invariant `self.pdev` is a valid address.
// CAST: The offset is cast to `i32` because the C functions expect a 32-bit
// signed offset parameter. PCI configuration space size is at most 4096 bytes,
// so the value always fits within `i32` without truncation or sign change.
unsafe { bindings::$read_fn(self.pdev.as_raw(), address as i32, &mut val) };
// SAFETY: By the type invariant `pdev` is a valid address.
let _ = unsafe { bindings::$read_fn(view.pdev.as_raw(), addr, &mut val) };
val
}
unsafe fn io_write(self, value: $ty, address: usize) {
fn io_write(view: ConfigSpace<'_, $ty>, value: $ty) {
// CAST: The offset is cast to `i32` because the C functions expect a 32-bit
// signed offset parameter. PCI configuration space size is at most 4096 bytes,
// so the value always fits within `i32` without truncation or sign change.
let addr = view.ptr.addr() as i32;
// Return value from C function is ignored in infallible accessors.
let _ret =
// SAFETY: By the type invariant `self.pdev` is a valid address.
// CAST: The offset is cast to `i32` because the C functions expect a 32-bit
// signed offset parameter. PCI configuration space size is at most 4096 bytes,
// so the value always fits within `i32` without truncation or sign change.
unsafe { bindings::$write_fn(self.pdev.as_raw(), address as i32, value) };
// SAFETY: By the type invariant `pdev` is a valid address.
let _ = unsafe { bindings::$write_fn(view.pdev.as_raw(), addr, value) };
}
}
};
@ -120,17 +146,13 @@ unsafe fn io_write(self, value: $ty, address: usize) {
impl_config_space_io_capable!(u16, pci_read_config_word, pci_write_config_word);
impl_config_space_io_capable!(u32, pci_read_config_dword, pci_write_config_dword);
impl<'a, T: ?Sized + KnownSize> Io for ConfigSpace<'a, T> {
impl<'a, T: ?Sized + KnownSize> Io<'a> for ConfigSpace<'a, T> {
type Backend = ConfigSpaceBackend;
type Target = T;
#[inline]
fn addr(self) -> usize {
self.ptr.addr()
}
#[inline]
fn maxsize(self) -> usize {
KnownSize::size(self.ptr)
fn as_view(self) -> ConfigSpace<'a, T> {
self
}
}