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Message-ID: <20240812182355.11641-8-dakr@kernel.org>
Date: Mon, 12 Aug 2024 20:22:53 +0200
From: Danilo Krummrich <dakr@...nel.org>
To: ojeda@...nel.org,
alex.gaynor@...il.com,
wedsonaf@...il.com,
boqun.feng@...il.com,
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Cc: daniel.almeida@...labora.com,
faith.ekstrand@...labora.com,
boris.brezillon@...labora.com,
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Danilo Krummrich <dakr@...nel.org>
Subject: [PATCH v5 07/26] rust: alloc: implement `KVmalloc` allocator
Implement `Allocator` for `KVmalloc`, an `Allocator` that tries to
allocate memory wth `kmalloc` first and, on failure, falls back to
`vmalloc`.
All memory allocations made with `KVmalloc` end up in
`kvrealloc_noprof()`; all frees in `kvfree()`.
Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>
Signed-off-by: Danilo Krummrich <dakr@...nel.org>
---
rust/helpers.c | 6 ++++++
rust/kernel/alloc/allocator.rs | 27 +++++++++++++++++++++++++++
rust/kernel/alloc/allocator_test.rs | 1 +
3 files changed, 34 insertions(+)
diff --git a/rust/helpers.c b/rust/helpers.c
index 7406943f887d..3285a85765ff 100644
--- a/rust/helpers.c
+++ b/rust/helpers.c
@@ -206,6 +206,12 @@ void *rust_helper_vrealloc(const void *p, size_t size, gfp_t flags)
}
EXPORT_SYMBOL_GPL(rust_helper_vrealloc);
+void *rust_helper_kvrealloc(const void *p, size_t size, gfp_t flags)
+{
+ return kvrealloc(p, size, flags);
+}
+EXPORT_SYMBOL_GPL(rust_helper_kvrealloc);
+
/*
* `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
* use it in contexts where Rust expects a `usize` like slice (array) indices.
diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs
index fdda22c6983f..243d8c49a57b 100644
--- a/rust/kernel/alloc/allocator.rs
+++ b/rust/kernel/alloc/allocator.rs
@@ -23,6 +23,12 @@
/// contiguous kernel virtual space.
pub struct Vmalloc;
+/// The kvmalloc kernel allocator.
+///
+/// Attempt to allocate physically contiguous memory, but upon failure, fall back to non-contiguous
+/// (vmalloc) allocation.
+pub struct KVmalloc;
+
/// 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.
@@ -65,6 +71,9 @@ impl ReallocFunc {
// INVARIANT: `vrealloc` satisfies the type invariants.
const VREALLOC: Self = Self(bindings::vrealloc);
+ // INVARIANT: `kvrealloc` satisfies the type invariants.
+ const KVREALLOC: Self = Self(bindings::kvrealloc);
+
/// # Safety
///
/// This method has the same safety requirements as `Allocator::realloc`.
@@ -160,6 +169,24 @@ unsafe fn realloc(
}
}
+unsafe impl Allocator for KVmalloc {
+ unsafe fn realloc(
+ ptr: Option<NonNull<u8>>,
+ layout: Layout,
+ flags: Flags,
+ ) -> Result<NonNull<[u8]>, AllocError> {
+ // TODO: Support alignments larger than PAGE_SIZE.
+ if layout.align() > bindings::PAGE_SIZE {
+ pr_warn!("KVmalloc 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::KVREALLOC.call(ptr, 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 e7bf2982f68f..1b2642c547ec 100644
--- a/rust/kernel/alloc/allocator_test.rs
+++ b/rust/kernel/alloc/allocator_test.rs
@@ -8,6 +8,7 @@
pub struct Kmalloc;
pub type Vmalloc = Kmalloc;
+pub type KVmalloc = Kmalloc;
unsafe impl Allocator for Kmalloc {
unsafe fn realloc(
--
2.45.2
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