| Message ID | 20241001150008.183102-9-dakr@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Generic `Allocator` support for Rust | expand |
On Tue, 1 Oct 2024 16:59:43 +0200 Danilo Krummrich <dakr@kernel.org> wrote: > Implement `Allocator` for `Vmalloc`, the kernel's virtually contiguous > allocator, typically used for larger objects, (much) larger than page > size. > > All memory allocations made with `Vmalloc` end up in `vrealloc()`. > > Reviewed-by: Alice Ryhl <aliceryhl@google.com> > Reviewed-by: Benno Lossin <benno.lossin@proton.me> > Signed-off-by: Danilo Krummrich <dakr@kernel.org> Reviewed-by: Gary Guo <gary@garyguo.net> > --- > rust/helpers/helpers.c | 1 + > rust/helpers/vmalloc.c | 9 +++++++ > rust/kernel/alloc/allocator.rs | 37 +++++++++++++++++++++++++++++ > rust/kernel/alloc/allocator_test.rs | 1 + > 4 files changed, 48 insertions(+) > create mode 100644 rust/helpers/vmalloc.c > > diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c > index 30f40149f3a9..20a0c69d5cc7 100644 > --- a/rust/helpers/helpers.c > +++ b/rust/helpers/helpers.c > @@ -22,5 +22,6 @@ > #include "spinlock.c" > #include "task.c" > #include "uaccess.c" > +#include "vmalloc.c" > #include "wait.c" > #include "workqueue.c" > diff --git a/rust/helpers/vmalloc.c b/rust/helpers/vmalloc.c > new file mode 100644 > index 000000000000..80d34501bbc0 > --- /dev/null > +++ b/rust/helpers/vmalloc.c > @@ -0,0 +1,9 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include <linux/vmalloc.h> > + > +void * __must_check __realloc_size(2) > +rust_helper_vrealloc(const void *p, size_t size, gfp_t flags) > +{ > + return vrealloc(p, size, flags); > +} > diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs > index 4f3c3ab7c7a2..f341e9ed5b7c 100644 > --- a/rust/kernel/alloc/allocator.rs > +++ b/rust/kernel/alloc/allocator.rs > @@ -15,6 +15,7 @@ > > use crate::alloc::{AllocError, Allocator}; > use crate::bindings; > +use crate::pr_warn; > > /// The contiguous kernel allocator. > /// > @@ -24,6 +25,15 @@ > /// For more details see [self]. > pub struct Kmalloc; > > +/// The virtually contiguous kernel allocator. > +/// > +/// `Vmalloc` allocates pages from the page level allocator and maps them into the contiguous kernel > +/// virtual space. It is typically used for large allocations. The memory allocated with this > +/// allocator is not physically contiguous. > +/// > +/// For more details see [self]. > +pub struct Vmalloc; > + > /// Returns a proper size to alloc a new object aligned to `new_layout`'s alignment. > fn aligned_size(new_layout: Layout) -> usize { > // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first. > @@ -63,6 +73,9 @@ impl ReallocFunc { > // INVARIANT: `krealloc` satisfies the type invariants. > const KREALLOC: Self = Self(bindings::krealloc); > > + // INVARIANT: `vrealloc` satisfies the type invariants. > + const VREALLOC: Self = Self(bindings::vrealloc); > + > /// # Safety > /// > /// This method has the same safety requirements as [`Allocator::realloc`]. > @@ -166,6 +179,30 @@ unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { > } > } > > +// SAFETY: `realloc` delegates to `ReallocFunc::call`, which guarantees that > +// - memory remains valid until it is explicitly freed, > +// - passing a pointer to a valid memory allocation is OK, > +// - `realloc` satisfies the guarantees, since `ReallocFunc::call` has the same. > +unsafe impl Allocator for Vmalloc { > + #[inline] > + unsafe fn realloc( > + ptr: Option<NonNull<u8>>, > + layout: Layout, > + old_layout: Layout, > + flags: Flags, > + ) -> Result<NonNull<[u8]>, AllocError> { > + // TODO: Support alignments larger than PAGE_SIZE. > + if layout.align() > bindings::PAGE_SIZE { > + pr_warn!("Vmalloc does not support alignments larger than PAGE_SIZE yet.\n"); > + return Err(AllocError); > + } > + > + // SAFETY: If not `None`, `ptr` is guaranteed to point to valid memory, which was previously > + // allocated with this `Allocator`. > + unsafe { ReallocFunc::VREALLOC.call(ptr, layout, old_layout, flags) } > + } > +} > + > #[global_allocator] > static ALLOCATOR: Kmalloc = Kmalloc; > > diff --git a/rust/kernel/alloc/allocator_test.rs b/rust/kernel/alloc/allocator_test.rs > index 4785efc474a7..e7bf2982f68f 100644 > --- a/rust/kernel/alloc/allocator_test.rs > +++ b/rust/kernel/alloc/allocator_test.rs > @@ -7,6 +7,7 @@ > use core::ptr::NonNull; > > pub struct Kmalloc; > +pub type Vmalloc = Kmalloc; > > unsafe impl Allocator for Kmalloc { > unsafe fn realloc(
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 30f40149f3a9..20a0c69d5cc7 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -22,5 +22,6 @@ #include "spinlock.c" #include "task.c" #include "uaccess.c" +#include "vmalloc.c" #include "wait.c" #include "workqueue.c" diff --git a/rust/helpers/vmalloc.c b/rust/helpers/vmalloc.c new file mode 100644 index 000000000000..80d34501bbc0 --- /dev/null +++ b/rust/helpers/vmalloc.c @@ -0,0 +1,9 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/vmalloc.h> + +void * __must_check __realloc_size(2) +rust_helper_vrealloc(const void *p, size_t size, gfp_t flags) +{ + return vrealloc(p, size, flags); +} diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs index 4f3c3ab7c7a2..f341e9ed5b7c 100644 --- a/rust/kernel/alloc/allocator.rs +++ b/rust/kernel/alloc/allocator.rs @@ -15,6 +15,7 @@ use crate::alloc::{AllocError, Allocator}; use crate::bindings; +use crate::pr_warn; /// The contiguous kernel allocator. /// @@ -24,6 +25,15 @@ /// For more details see [self]. pub struct Kmalloc; +/// The virtually contiguous kernel allocator. +/// +/// `Vmalloc` allocates pages from the page level allocator and maps them into the contiguous kernel +/// virtual space. It is typically used for large allocations. The memory allocated with this +/// allocator is not physically contiguous. +/// +/// For more details see [self]. +pub struct Vmalloc; + /// Returns a proper size to alloc a new object aligned to `new_layout`'s alignment. fn aligned_size(new_layout: Layout) -> usize { // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first. @@ -63,6 +73,9 @@ impl ReallocFunc { // INVARIANT: `krealloc` satisfies the type invariants. const KREALLOC: Self = Self(bindings::krealloc); + // INVARIANT: `vrealloc` satisfies the type invariants. + const VREALLOC: Self = Self(bindings::vrealloc); + /// # Safety /// /// This method has the same safety requirements as [`Allocator::realloc`]. @@ -166,6 +179,30 @@ unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { } } +// SAFETY: `realloc` delegates to `ReallocFunc::call`, which guarantees that +// - memory remains valid until it is explicitly freed, +// - passing a pointer to a valid memory allocation is OK, +// - `realloc` satisfies the guarantees, since `ReallocFunc::call` has the same. +unsafe impl Allocator for Vmalloc { + #[inline] + unsafe fn realloc( + ptr: Option<NonNull<u8>>, + layout: Layout, + old_layout: Layout, + flags: Flags, + ) -> Result<NonNull<[u8]>, AllocError> { + // TODO: Support alignments larger than PAGE_SIZE. + if layout.align() > bindings::PAGE_SIZE { + pr_warn!("Vmalloc does not support alignments larger than PAGE_SIZE yet.\n"); + return Err(AllocError); + } + + // SAFETY: If not `None`, `ptr` is guaranteed to point to valid memory, which was previously + // allocated with this `Allocator`. + unsafe { ReallocFunc::VREALLOC.call(ptr, layout, old_layout, flags) } + } +} + #[global_allocator] static ALLOCATOR: Kmalloc = Kmalloc; diff --git a/rust/kernel/alloc/allocator_test.rs b/rust/kernel/alloc/allocator_test.rs index 4785efc474a7..e7bf2982f68f 100644 --- a/rust/kernel/alloc/allocator_test.rs +++ b/rust/kernel/alloc/allocator_test.rs @@ -7,6 +7,7 @@ use core::ptr::NonNull; pub struct Kmalloc; +pub type Vmalloc = Kmalloc; unsafe impl Allocator for Kmalloc { unsafe fn realloc(