`Vec` provides a contiguous growable array type (such as `Vec`) with
contents allocated with the kernel's allocators (e.g. `Kmalloc`,
`Vmalloc` or `KVmalloc`).
In contrast to Rust's `Vec` type, the kernel `Vec` type considers the
kernel's GFP flags for all appropriate functions, always reports
allocation failures through `Result<_, AllocError>` and remains
independent from unstable features.
Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
rust/kernel/alloc.rs | 6 +
rust/kernel/alloc/kbox.rs | 16 +-
rust/kernel/alloc/kvec.rs | 583 ++++++++++++++++++++++++++++++++++++++
rust/kernel/prelude.rs | 2 +-
4 files changed, 605 insertions(+), 2 deletions(-)
create mode 100644 rust/kernel/alloc/kvec.rs
diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index 4bddd023aa7f..bd93140f3094 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -5,6 +5,7 @@
#[cfg(not(any(test, testlib)))]
pub mod allocator;
pub mod kbox;
+pub mod kvec;
pub mod vec_ext;
#[cfg(any(test, testlib))]
@@ -18,6 +19,11 @@
pub use self::kbox::KVBox;
pub use self::kbox::VBox;
+pub use self::kvec::KVVec;
+pub use self::kvec::KVec;
+pub use self::kvec::VVec;
+pub use self::kvec::Vec;
+
/// Indicates an allocation error.
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub struct AllocError;
diff --git a/rust/kernel/alloc/kbox.rs b/rust/kernel/alloc/kbox.rs
index 7074f00e07bc..39feaed4a8f8 100644
--- a/rust/kernel/alloc/kbox.rs
+++ b/rust/kernel/alloc/kbox.rs
@@ -2,7 +2,7 @@
//! Implementation of [`Box`].
-use super::{AllocError, Allocator, Flags};
+use super::{AllocError, Allocator, Flags, Vec};
use core::fmt;
use core::marker::PhantomData;
use core::mem::ManuallyDrop;
@@ -169,6 +169,20 @@ pub fn into_pin(b: Self) -> Pin<Self>
}
}
+impl<T, A, const N: usize> Box<[T; N], A>
+where
+ A: Allocator,
+{
+ /// Convert a `Box<[T], A>` to a `Vec<T, A>`.
+ pub fn into_vec(b: Self) -> Vec<T, A> {
+ let len = b.len();
+ unsafe {
+ let ptr = Self::into_raw(b);
+ Vec::from_raw_parts(ptr as _, len, len)
+ }
+ }
+}
+
impl<T, A> Box<MaybeUninit<T>, A>
where
A: Allocator,
diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs
new file mode 100644
index 000000000000..04cc85f7d92c
--- /dev/null
+++ b/rust/kernel/alloc/kvec.rs
@@ -0,0 +1,583 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Implementation of [`Vec`].
+
+use super::{AllocError, Allocator, Flags};
+use crate::types::Unique;
+use core::{
+ fmt,
+ marker::PhantomData,
+ mem::{ManuallyDrop, MaybeUninit},
+ ops::Deref,
+ ops::DerefMut,
+ ops::Index,
+ ops::IndexMut,
+ slice,
+ slice::SliceIndex,
+};
+
+/// Create a [`Vec`] containing the arguments.
+///
+/// # Examples
+///
+/// ```
+/// let mut v = kernel::kvec![];
+/// v.push(1, GFP_KERNEL)?;
+/// assert_eq!(v, [1]);
+///
+/// let mut v = kernel::kvec![1; 3]?;
+/// v.push(4, GFP_KERNEL)?;
+/// assert_eq!(v, [1, 1, 1, 4]);
+///
+/// let mut v = kernel::kvec![1, 2, 3]?;
+/// v.push(4, GFP_KERNEL)?;
+/// assert_eq!(v, [1, 2, 3, 4]);
+///
+/// # Ok::<(), Error>(())
+/// ```
+#[macro_export]
+macro_rules! kvec {
+ () => (
+ {
+ $crate::alloc::KVec::new()
+ }
+ );
+ ($elem:expr; $n:expr) => (
+ {
+ $crate::alloc::KVec::from_elem($elem, $n, GFP_KERNEL)
+ }
+ );
+ ($($x:expr),+ $(,)?) => (
+ {
+ match $crate::alloc::KBox::new([$($x),+], GFP_KERNEL) {
+ Ok(b) => Ok($crate::alloc::KBox::into_vec(b)),
+ Err(e) => Err(e),
+ }
+ }
+ );
+}
+
+/// The kernel's [`Vec`] type.
+///
+/// A contiguous growable array type with contents allocated with the kernel's allocators (e.g.
+/// `Kmalloc`, `Vmalloc` or `KVmalloc`, written `Vec<T, A>`.
+///
+/// For non-zero-sized values, a [`Vec`] will use the given allocator `A` for its allocation. For
+/// the most common allocators the type aliases `KVec`, `VVec` and `KVVec` exist.
+///
+/// For zero-sized types the [`Vec`]'s pointer must be `dangling_mut::<T>`; no memory is allocated.
+///
+/// Generally, [`Vec`] consists of a pointer that represents the vector's backing buffer, the
+/// capacity of the vector (the number of elements that currently fit into the vector), it's length
+/// (the number of elements that are currently stored in the vector) and the `Allocator` used to
+/// allocate (and free) the backing buffer.
+///
+/// A [`Vec`] can be deconstructed into and (re-)constructed from it's previously named raw parts
+/// and manually modified.
+///
+/// [`Vec`]'s backing buffer gets, if required, automatically increased (re-allocated) when elements
+/// are added to the vector.
+///
+/// # Invariants
+///
+/// The [`Vec`] backing buffer's pointer always properly aligned and either points to memory
+/// allocated with `A` or, for zero-sized types, is a dangling pointer.
+///
+/// The length of the vector always represents the exact number of elements stored in the vector.
+///
+/// The capacity of the vector always represents the absolute number of elements that can be stored
+/// within the vector without re-allocation. However, it is legal for the backing buffer to be
+/// larger than `size_of<T>` times the capacity.
+///
+/// The `Allocator` of the vector is the exact allocator the backing buffer was allocated with (and
+/// must be freed with).
+pub struct Vec<T, A: Allocator> {
+ ptr: Unique<T>,
+ /// Never used for ZSTs; it's `capacity()`'s responsibility to return usize::MAX in that case.
+ ///
+ /// # Safety
+ ///
+ /// `cap` must be in the `0..=isize::MAX` range.
+ cap: usize,
+ len: usize,
+ _p: PhantomData<A>,
+}
+
+/// Type alias for `Vec` with a `Kmalloc` allocator.
+///
+/// # Examples
+///
+/// ```
+/// let mut v = KVec::new();
+/// v.push(1, GFP_KERNEL)?;
+/// assert_eq!(&v, &[1]);
+///
+/// # Ok::<(), Error>(())
+/// ```
+pub type KVec<T> = Vec<T, super::allocator::Kmalloc>;
+
+/// Type alias for `Vec` with a `Vmalloc` allocator.
+///
+/// # Examples
+///
+/// ```
+/// let mut v = VVec::new();
+/// v.push(1, GFP_KERNEL)?;
+/// assert_eq!(&v, &[1]);
+///
+/// # Ok::<(), Error>(())
+/// ```
+pub type VVec<T> = Vec<T, super::allocator::Vmalloc>;
+
+/// Type alias for `Vec` with a `KVmalloc` allocator.
+///
+/// # Examples
+///
+/// ```
+/// let mut v = KVVec::new();
+/// v.push(1, GFP_KERNEL)?;
+/// assert_eq!(&v, &[1]);
+///
+/// # Ok::<(), Error>(())
+/// ```
+pub type KVVec<T> = Vec<T, super::allocator::KVmalloc>;
+
+impl<T, A> Vec<T, A>
+where
+ A: Allocator,
+{
+ #[inline]
+ fn is_zst() -> bool {
+ core::mem::size_of::<T>() == 0
+ }
+
+ /// Returns the total number of elements the vector can hold without
+ /// reallocating.
+ pub fn capacity(&self) -> usize {
+ if Self::is_zst() {
+ usize::MAX
+ } else {
+ self.cap
+ }
+ }
+
+ /// Returns the number of elements in the vector, also referred to
+ /// as its 'length'.
+ #[inline]
+ pub fn len(&self) -> usize {
+ self.len
+ }
+
+ /// Forces the length of the vector to new_len.
+ ///
+ /// # Safety
+ ///
+ /// - `new_len` must be less than or equal to [`Self::capacity()`].
+ /// - The elements at `old_len..new_len` must be initialized.
+ #[inline]
+ pub unsafe fn set_len(&mut self, new_len: usize) {
+ self.len = new_len;
+ }
+
+ /// Extracts a slice containing the entire vector.
+ ///
+ /// Equivalent to `&s[..]`.
+ #[inline]
+ pub fn as_slice(&self) -> &[T] {
+ self
+ }
+
+ /// Extracts a mutable slice of the entire vector.
+ ///
+ /// Equivalent to `&mut s[..]`.
+ #[inline]
+ pub fn as_mut_slice(&mut self) -> &mut [T] {
+ self
+ }
+
+ /// Returns an unsafe mutable pointer to the vector's buffer, or a dangling
+ /// raw pointer valid for zero sized reads if the vector didn't allocate.
+ #[inline]
+ pub fn as_mut_ptr(&self) -> *mut T {
+ self.ptr.as_ptr()
+ }
+
+ /// Returns a raw pointer to the slice's buffer.
+ #[inline]
+ pub fn as_ptr(&self) -> *const T {
+ self.as_mut_ptr()
+ }
+
+ /// Returns `true` if the vector contains no elements.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// let mut v = KVec::new();
+ /// assert!(v.is_empty());
+ ///
+ /// v.push(1, GFP_KERNEL);
+ /// assert!(!v.is_empty());
+ /// ```
+ #[inline]
+ pub fn is_empty(&self) -> bool {
+ self.len() == 0
+ }
+
+ /// Constructs a new, empty Vec<T, A>.
+ ///
+ /// This method does not allocate by itself.
+ #[inline]
+ pub const fn new() -> Self {
+ Self {
+ ptr: Unique::dangling(),
+ cap: 0,
+ len: 0,
+ _p: PhantomData::<A>,
+ }
+ }
+
+ /// Returns the remaining spare capacity of the vector as a slice of `MaybeUninit<T>`.
+ pub fn spare_capacity_mut(&mut self) -> &mut [MaybeUninit<T>] {
+ // SAFETY: The memory between `self.len` and `self.capacity` is guaranteed to be allocated
+ // and valid, but uninitialized.
+ unsafe {
+ slice::from_raw_parts_mut(
+ self.as_mut_ptr().add(self.len) as *mut MaybeUninit<T>,
+ self.capacity() - self.len,
+ )
+ }
+ }
+
+ /// Appends an element to the back of the [`Vec`] instance.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// let mut v = KVec::new();
+ /// v.push(1, GFP_KERNEL)?;
+ /// assert_eq!(&v, &[1]);
+ ///
+ /// v.push(2, GFP_KERNEL)?;
+ /// assert_eq!(&v, &[1, 2]);
+ /// # Ok::<(), Error>(())
+ /// ```
+ pub fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> {
+ Vec::reserve(self, 1, flags)?;
+ let s = self.spare_capacity_mut();
+ s[0].write(v);
+
+ // SAFETY: We just initialised the first spare entry, so it is safe to increase the length
+ // by 1. We also know that the new length is <= capacity because of the previous call to
+ // `reserve` above.
+ unsafe { self.set_len(self.len() + 1) };
+ Ok(())
+ }
+
+ /// Creates a new [`Vec`] instance with at least the given capacity.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// let v = KVec::<u32>::with_capacity(20, GFP_KERNEL)?;
+ ///
+ /// assert!(v.capacity() >= 20);
+ /// # Ok::<(), Error>(())
+ /// ```
+ pub fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError> {
+ let mut v = Vec::new();
+
+ Self::reserve(&mut v, capacity, flags)?;
+
+ Ok(v)
+ }
+
+ /// Pushes clones of the elements of slice into the [`Vec`] instance.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// let mut v = KVec::new();
+ /// v.push(1, GFP_KERNEL)?;
+ ///
+ /// v.extend_from_slice(&[20, 30, 40], GFP_KERNEL)?;
+ /// assert_eq!(&v, &[1, 20, 30, 40]);
+ ///
+ /// v.extend_from_slice(&[50, 60], GFP_KERNEL)?;
+ /// assert_eq!(&v, &[1, 20, 30, 40, 50, 60]);
+ /// # Ok::<(), Error>(())
+ /// ```
+ pub fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>
+ where
+ T: Clone,
+ {
+ self.reserve(other.len(), flags)?;
+ for (slot, item) in core::iter::zip(self.spare_capacity_mut(), other) {
+ slot.write(item.clone());
+ }
+
+ // SAFETY: We just initialised the `other.len()` spare entries, so it is safe to increase
+ // the length by the same amount. We also know that the new length is <= capacity because
+ // of the previous call to `reserve` above.
+ unsafe { self.set_len(self.len() + other.len()) };
+ Ok(())
+ }
+
+ /// Creates a Vec<T, A> directly from a pointer, a length, a capacity, and an allocator.
+ ///
+ /// # Safety
+ ///
+ /// This is highly unsafe, due to the number of invariants that aren’t checked:
+ ///
+ /// - `ptr` must be currently allocated via the given allocator `A`.
+ /// - `T` needs to have the same alignment as what `ptr` was allocated with. (`T` having a less
+ /// strict alignment is not sufficient, the alignment really needs to be equal to satisfy the
+ /// `dealloc` requirement that memory must be allocated and deallocated with the same layout.)
+ /// - The size of `T` times the `capacity` (i.e. the allocated size in bytes) needs to be
+ /// smaller or equal the size the pointer was allocated with.
+ /// - `length` needs to be less than or equal to `capacity`.
+ /// - The first `length` values must be properly initialized values of type `T`.
+ /// - The allocated size in bytes must be no larger than `isize::MAX`. See the safety
+ /// documentation of `pointer::offset`.
+ ///
+ /// It is also valid to create an empty `Vec` passing a dangling pointer for `ptr` and zero for
+ /// `cap` and `len`.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// let mut v = kernel::kvec![1, 2, 3]?;
+ /// v.reserve(1, GFP_KERNEL)?;
+ ///
+ /// let (mut ptr, mut len, cap) = v.into_raw_parts();
+ ///
+ /// // SAFETY: We've just reserved memory for another element.
+ /// unsafe { ptr.add(len).write(4) };
+ /// len += 1;
+ ///
+ /// // SAFETY: We only wrote an additional element at the end of the `KVec`'s buffer and
+ /// // correspondingly increased the length of the `KVec` by one. Otherwise, we construct it
+ /// // from the exact same raw parts.
+ /// let v = unsafe { KVec::from_raw_parts(ptr, len, cap) };
+ ///
+ /// assert_eq!(v, [1, 2, 3, 4]);
+ ///
+ /// # Ok::<(), Error>(())
+ /// ```
+ pub unsafe fn from_raw_parts(ptr: *mut T, length: usize, capacity: usize) -> Self {
+ let cap = if Self::is_zst() { 0 } else { capacity };
+
+ Self {
+ // SAFETY: By the safety requirements, `ptr` is either dangling or pointing to a valid
+ // memory allocation, allocated with `A`.
+ ptr: unsafe { Unique::new_unchecked(ptr) },
+ cap,
+ len: length,
+ _p: PhantomData::<A>,
+ }
+ }
+
+ /// Decomposes a `Vec<T, A>` into its raw components: (`pointer`, `length`, `capacity`).
+ pub fn into_raw_parts(self) -> (*mut T, usize, usize) {
+ let me = ManuallyDrop::new(self);
+ let len = me.len();
+ let capacity = me.capacity();
+ let ptr = me.as_mut_ptr();
+ (ptr, len, capacity)
+ }
+
+ /// Ensures that the capacity exceeds the length by at least `additional` elements.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// let mut v = KVec::new();
+ /// v.push(1, GFP_KERNEL)?;
+ ///
+ /// v.reserve(10, GFP_KERNEL)?;
+ /// let cap = v.capacity();
+ /// assert!(cap >= 10);
+ ///
+ /// v.reserve(10, GFP_KERNEL)?;
+ /// let new_cap = v.capacity();
+ /// assert_eq!(new_cap, cap);
+ ///
+ /// # Ok::<(), Error>(())
+ /// ```
+ pub fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError> {
+ let len = self.len();
+ let cap = self.capacity();
+
+ if cap - len >= additional {
+ return Ok(());
+ }
+
+ if Self::is_zst() {
+ // The capacity is already `usize::MAX` for SZTs, we can't go higher.
+ return Err(AllocError);
+ }
+
+ // We know cap is <= `isize::MAX` because `Layout::array` fails if the resulting byte size
+ // is greater than `isize::MAX`. So the multiplication by two won't overflow.
+ let new_cap = core::cmp::max(cap * 2, len.checked_add(additional).ok_or(AllocError)?);
+ let layout = core::alloc::Layout::array::<T>(new_cap).map_err(|_| AllocError)?;
+
+ // We need to make sure that `ptr` is either NULL or comes from a previous call to
+ // `realloc_flags`. A `Vec<T, A>`'s `ptr` value is not guaranteed to be NULL and might be
+ // dangling after being created with `Vec::new`. Instead, we can rely on `Vec<T, A>`'s
+ // capacity to be zero if no memory has been allocated yet.
+ let ptr = if cap == 0 {
+ None
+ } else {
+ Some(self.ptr.as_non_null().cast())
+ };
+
+ // SAFETY: `ptr` is valid because it's either `None` or comes from a previous call to
+ // `A::realloc`. We also verified that the type is not a ZST.
+ let ptr = unsafe { A::realloc(ptr, layout, flags)? };
+
+ self.ptr = ptr.cast().into();
+ self.cap = new_cap;
+
+ Ok(())
+ }
+}
+
+impl<T: Clone, A: Allocator> Vec<T, A> {
+ /// Extend the vector by `n` clones of value.
+ pub fn extend_with(&mut self, n: usize, value: T, flags: Flags) -> Result<(), AllocError> {
+ self.reserve(n, flags)?;
+
+ let spare = self.spare_capacity_mut();
+
+ for i in 0..spare.len() - 1 {
+ spare[i].write(value.clone());
+ }
+
+ // We can write the last element directly without cloning needlessly
+ spare[spare.len() - 1].write(value);
+
+ // SAFETY: `self.reserve` not bailing out with an error guarantees that we're not
+ // exceeding the capacity of this `Vec`.
+ unsafe { self.set_len(self.len() + n) };
+
+ Ok(())
+ }
+
+ /// Create a new `Vec<T, A> and extend it by `n` clones of `value`.
+ pub fn from_elem(value: T, n: usize, flags: Flags) -> Result<Self, AllocError> {
+ let mut v = Self::with_capacity(n, flags)?;
+
+ v.extend_with(n, value, flags)?;
+
+ Ok(v)
+ }
+}
+
+impl<T, A> Drop for Vec<T, A>
+where
+ A: Allocator,
+{
+ fn drop(&mut self) {
+ // SAFETY: We need to drop the vector's elements in place, before we free the backing
+ // memory.
+ unsafe {
+ core::ptr::drop_in_place(core::ptr::slice_from_raw_parts_mut(
+ self.as_mut_ptr(),
+ self.len,
+ ))
+ };
+
+ // If `cap == 0` we never allocated any memory in the first place.
+ if self.cap != 0 {
+ // SAFETY: `self.ptr` was previously allocated with `A`.
+ unsafe { A::free(self.ptr.as_non_null().cast()) };
+ }
+ }
+}
+
+impl<T> Default for KVec<T> {
+ #[inline]
+ fn default() -> Self {
+ Self::new()
+ }
+}
+
+impl<T: fmt::Debug, A: Allocator> fmt::Debug for Vec<T, A> {
+ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+ fmt::Debug::fmt(&**self, f)
+ }
+}
+
+impl<T, A> Deref for Vec<T, A>
+where
+ A: Allocator,
+{
+ type Target = [T];
+
+ #[inline]
+ fn deref(&self) -> &[T] {
+ // SAFETY: The memory behind `self.as_ptr()` is guaranteed to contain `self.len`
+ // initialized elements of type `T`.
+ unsafe { slice::from_raw_parts(self.as_ptr(), self.len) }
+ }
+}
+
+impl<T, A> DerefMut for Vec<T, A>
+where
+ A: Allocator,
+{
+ #[inline]
+ fn deref_mut(&mut self) -> &mut [T] {
+ // SAFETY: The memory behind `self.as_ptr()` is guaranteed to contain `self.len`
+ // initialized elements of type `T`.
+ unsafe { slice::from_raw_parts_mut(self.as_mut_ptr(), self.len) }
+ }
+}
+
+impl<T: Eq, A> Eq for Vec<T, A> where A: Allocator {}
+
+impl<T, I: SliceIndex<[T]>, A> Index<I> for Vec<T, A>
+where
+ A: Allocator,
+{
+ type Output = I::Output;
+
+ #[inline]
+ fn index(&self, index: I) -> &Self::Output {
+ Index::index(&**self, index)
+ }
+}
+
+impl<T, I: SliceIndex<[T]>, A> IndexMut<I> for Vec<T, A>
+where
+ A: Allocator,
+{
+ #[inline]
+ fn index_mut(&mut self, index: I) -> &mut Self::Output {
+ IndexMut::index_mut(&mut **self, index)
+ }
+}
+
+macro_rules! __impl_slice_eq {
+ ([$($vars:tt)*] $lhs:ty, $rhs:ty $(where $ty:ty: $bound:ident)?) => {
+ impl<T, U, $($vars)*> PartialEq<$rhs> for $lhs
+ where
+ T: PartialEq<U>,
+ $($ty: $bound)?
+ {
+ #[inline]
+ fn eq(&self, other: &$rhs) -> bool { self[..] == other[..] }
+ }
+ }
+}
+
+__impl_slice_eq! { [A1: Allocator, A2: Allocator] Vec<T, A1>, Vec<U, A2> }
+__impl_slice_eq! { [A: Allocator] Vec<T, A>, &[U] }
+__impl_slice_eq! { [A: Allocator] Vec<T, A>, &mut [U] }
+__impl_slice_eq! { [A: Allocator] &[T], Vec<U, A> }
+__impl_slice_eq! { [A: Allocator] &mut [T], Vec<U, A> }
+__impl_slice_eq! { [A: Allocator] Vec<T, A>, [U] }
+__impl_slice_eq! { [A: Allocator] [T], Vec<U, A> }
+__impl_slice_eq! { [A: Allocator, const N: usize] Vec<T, A>, [U; N] }
+__impl_slice_eq! { [A: Allocator, const N: usize] Vec<T, A>, &[U; N] }
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index 6bf77577eae7..bb80a43d20fb 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -14,7 +14,7 @@
#[doc(no_inline)]
pub use core::pin::Pin;
-pub use crate::alloc::{flags::*, vec_ext::VecExt, Box, KBox, KVBox, VBox};
+pub use crate::alloc::{flags::*, vec_ext::VecExt, Box, KBox, KVBox, KVVec, KVec, VBox, VVec};
#[doc(no_inline)]
pub use alloc::vec::Vec;
--
2.45.2
