From 31d94d8f586df55e7dce47a67a8428f46d09f906 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Wed, 27 Mar 2024 22:35:54 -0300 Subject: rust: kernel: move `allocator` module under `alloc` We will add more to the `alloc` module in subsequent patches (e.g., allocation flags and extension traits). Reviewed-by: Benno Lossin Signed-off-by: Wedson Almeida Filho Link: https://lore.kernel.org/r/20240328013603.206764-2-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/alloc/allocator.rs | 88 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 rust/kernel/alloc/allocator.rs (limited to 'rust/kernel/alloc/allocator.rs') diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs new file mode 100644 index 000000000000..01ad139e19bc --- /dev/null +++ b/rust/kernel/alloc/allocator.rs @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Allocator support. + +use core::alloc::{GlobalAlloc, Layout}; +use core::ptr; + +use crate::bindings; + +struct KernelAllocator; + +/// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment. +/// +/// # Safety +/// +/// - `ptr` can be either null or a pointer which has been allocated by this allocator. +/// - `new_layout` must have a non-zero size. +unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 { + // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first. + let layout = new_layout.pad_to_align(); + + let mut size = layout.size(); + + if layout.align() > bindings::ARCH_SLAB_MINALIGN { + // The alignment requirement exceeds the slab guarantee, thus try to enlarge the size + // to use the "power-of-two" size/alignment guarantee (see comments in `kmalloc()` for + // more information). + // + // Note that `layout.size()` (after padding) is guaranteed to be a multiple of + // `layout.align()`, so `next_power_of_two` gives enough alignment guarantee. + size = size.next_power_of_two(); + } + + // SAFETY: + // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the + // function safety requirement. + // - `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero + // according to the function safety requirement) or a result from `next_power_of_two()`. + unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags) as *mut u8 } +} + +unsafe impl GlobalAlloc for KernelAllocator { + unsafe fn alloc(&self, layout: Layout) -> *mut u8 { + // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety + // requirement. + unsafe { krealloc_aligned(ptr::null_mut(), layout, bindings::GFP_KERNEL) } + } + + unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) { + unsafe { + bindings::kfree(ptr as *const core::ffi::c_void); + } + } + + unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + // SAFETY: + // - `new_size`, when rounded up to the nearest multiple of `layout.align()`, will not + // overflow `isize` by the function safety requirement. + // - `layout.align()` is a proper alignment (i.e. not zero and must be a power of two). + let layout = unsafe { Layout::from_size_align_unchecked(new_size, layout.align()) }; + + // SAFETY: + // - `ptr` is either null or a pointer allocated by this allocator by the function safety + // requirement. + // - the size of `layout` is not zero because `new_size` is not zero by the function safety + // requirement. + unsafe { krealloc_aligned(ptr, layout, bindings::GFP_KERNEL) } + } + + unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { + // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety + // requirement. + unsafe { + krealloc_aligned( + ptr::null_mut(), + layout, + bindings::GFP_KERNEL | bindings::__GFP_ZERO, + ) + } + } +} + +#[global_allocator] +static ALLOCATOR: KernelAllocator = KernelAllocator; + +// See . +#[no_mangle] +static __rust_no_alloc_shim_is_unstable: u8 = 0; -- cgit v1.2.3 From b6a006e21b822d1dd262fa249ff71a2991e7b319 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Wed, 27 Mar 2024 22:35:58 -0300 Subject: rust: alloc: introduce allocation flags We'll use them when allocating `Box`, `Arc`, and `UniqueArc` instances, as well as when allocating memory for `Vec` elements. These changes will come in subsequent patches. Reviewed-by: Benno Lossin Signed-off-by: Wedson Almeida Filho Link: https://lore.kernel.org/r/20240328013603.206764-6-wedsonaf@gmail.com Signed-off-by: Miguel Ojeda --- rust/kernel/alloc/allocator.rs | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-) (limited to 'rust/kernel/alloc/allocator.rs') diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs index 01ad139e19bc..8cc7099d6ae1 100644 --- a/rust/kernel/alloc/allocator.rs +++ b/rust/kernel/alloc/allocator.rs @@ -2,6 +2,7 @@ //! Allocator support. +use super::{flags::*, Flags}; use core::alloc::{GlobalAlloc, Layout}; use core::ptr; @@ -15,7 +16,7 @@ struct KernelAllocator; /// /// - `ptr` can be either null or a pointer which has been allocated by this allocator. /// - `new_layout` must have a non-zero size. -unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gfp_t) -> *mut u8 { +unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 { // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first. let layout = new_layout.pad_to_align(); @@ -36,14 +37,14 @@ unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: bindings::gf // function safety requirement. // - `size` is greater than 0 since it's either a `layout.size()` (which cannot be zero // according to the function safety requirement) or a result from `next_power_of_two()`. - unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags) as *mut u8 } + unsafe { bindings::krealloc(ptr as *const core::ffi::c_void, size, flags.0) as *mut u8 } } unsafe impl GlobalAlloc for KernelAllocator { unsafe fn alloc(&self, layout: Layout) -> *mut u8 { // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety // requirement. - unsafe { krealloc_aligned(ptr::null_mut(), layout, bindings::GFP_KERNEL) } + unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL) } } unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) { @@ -64,19 +65,13 @@ unsafe impl GlobalAlloc for KernelAllocator { // requirement. // - the size of `layout` is not zero because `new_size` is not zero by the function safety // requirement. - unsafe { krealloc_aligned(ptr, layout, bindings::GFP_KERNEL) } + unsafe { krealloc_aligned(ptr, layout, GFP_KERNEL) } } unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { // SAFETY: `ptr::null_mut()` is null and `layout` has a non-zero size by the function safety // requirement. - unsafe { - krealloc_aligned( - ptr::null_mut(), - layout, - bindings::GFP_KERNEL | bindings::__GFP_ZERO, - ) - } + unsafe { krealloc_aligned(ptr::null_mut(), layout, GFP_KERNEL | __GFP_ZERO) } } } -- cgit v1.2.3 From 08d3f54928796557fc832467ad54f04908fc14e4 Mon Sep 17 00:00:00 2001 From: Wedson Almeida Filho Date: Wed, 27 Mar 2024 22:35:59 -0300 Subject: rust: alloc: introduce the `BoxExt` trait Make fallible versions of `new` and `new_uninit` methods available in `Box` even though it doesn't implement them because we build `alloc` with the `no_global_oom_handling` config. They also have an extra `flags` parameter that allows callers to pass flags to the allocator. Signed-off-by: Wedson Almeida Filho Reviewed-by: Boqun Feng Reviewed-by: Benno Lossin Link: https://lore.kernel.org/r/20240328013603.206764-7-wedsonaf@gmail.com [ Used `Box::write()` to avoid one `unsafe` block as suggested by Boqun. ] Signed-off-by: Miguel Ojeda --- rust/kernel/alloc/allocator.rs | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'rust/kernel/alloc/allocator.rs') diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs index 8cc7099d6ae1..ff88bce04fd4 100644 --- a/rust/kernel/alloc/allocator.rs +++ b/rust/kernel/alloc/allocator.rs @@ -16,7 +16,7 @@ struct KernelAllocator; /// /// - `ptr` can be either null or a pointer which has been allocated by this allocator. /// - `new_layout` must have a non-zero size. -unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 { +pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 { // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first. let layout = new_layout.pad_to_align(); -- cgit v1.2.3 From 00280272a0e5d98055e4d47db38a9b4b5517520e Mon Sep 17 00:00:00 2001 From: Miguel Ojeda Date: Mon, 1 Apr 2024 23:23:02 +0200 Subject: rust: kernel: remove redundant imports Rust's `unused_imports` lint covers both unused and redundant imports. In the upcoming 1.78.0, the lint detects more cases of redundant imports [1], e.g.: error: the item `bindings` is imported redundantly --> rust/kernel/print.rs:38:9 | 38 | use crate::bindings; | ^^^^^^^^^^^^^^^ the item `bindings` is already defined by prelude Most cases are `use crate::bindings`, plus a few other items like `Box`. Thus clean them up. Note that, in the `bindings` case, the message "defined by prelude" above means the extern prelude, i.e. the `--extern` flags we pass. Link: https://github.com/rust-lang/rust/pull/117772 [1] Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20240401212303.537355-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda --- rust/kernel/alloc/allocator.rs | 2 -- 1 file changed, 2 deletions(-) (limited to 'rust/kernel/alloc/allocator.rs') diff --git a/rust/kernel/alloc/allocator.rs b/rust/kernel/alloc/allocator.rs index ff88bce04fd4..229642960cd1 100644 --- a/rust/kernel/alloc/allocator.rs +++ b/rust/kernel/alloc/allocator.rs @@ -6,8 +6,6 @@ use super::{flags::*, Flags}; use core::alloc::{GlobalAlloc, Layout}; use core::ptr; -use crate::bindings; - struct KernelAllocator; /// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment. -- cgit v1.2.3