diff --git a/library/core/src/alloc/global.rs b/library/core/src/alloc/global.rs index e97398aa5dc4a..44a8ab6e54196 100644 --- a/library/core/src/alloc/global.rs +++ b/library/core/src/alloc/global.rs @@ -1,4 +1,7 @@ +use super::{AllocError, GlobalAllocator}; use crate::alloc::Layout; +use crate::hint::assert_unchecked; +use crate::ptr::NonNull; use crate::{cmp, ptr}; /// A memory allocator that can be registered as the standard library’s default @@ -301,3 +304,72 @@ pub unsafe trait GlobalAlloc { new_ptr } } + +/// Allows all [`GlobalAllocator`]s to be used with the legacy [`GlobalAlloc`] interface. +#[stable(feature = "global_alloc", since = "1.28.0")] +unsafe impl GlobalAlloc for A +where + A: GlobalAllocator + ?Sized, +{ + unsafe fn alloc(&self, layout: Layout) -> *mut u8 { + // SAFETY: guaranteed by the caller. + // This might lead to the removal of zero-size checks inside the + // `Allocator` implementation. + unsafe { assert_unchecked(layout.size() != 0) }; + match self.allocate(layout) { + Ok(ptr) => ptr.cast().as_ptr(), + Err(AllocError) => ptr::null_mut(), + } + } + + unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { + // SAFETY: guaranteed by the caller. + unsafe { assert_unchecked(layout.size() != 0) }; + // SAFETY: only non-null pointers can be currently allocated. + let ptr = unsafe { NonNull::new_unchecked(ptr) }; + // SAFETY: guaranteed by caller. + unsafe { self.deallocate(ptr, layout) }; + } + + unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { + // SAFETY: guaranteed by the caller. + unsafe { assert_unchecked(layout.size() != 0) }; + match self.allocate_zeroed(layout) { + Ok(ptr) => ptr.cast().as_ptr(), + Err(AllocError) => ptr::null_mut(), + } + } + + unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + // SAFETY: guaranteed by the caller. + unsafe { assert_unchecked(layout.size() != 0) }; + // SAFETY: guaranteed by the caller. + unsafe { assert_unchecked(new_size != 0) }; + + // SAFETY: only non-null pointers can be currently allocated. + let ptr = unsafe { NonNull::new_unchecked(ptr) }; + let alignment = layout.alignment(); + // SAFETY: the caller must ensure that the `new_size` does not overflow + // when rounded up to the next multiple of `alignment`. + let new_layout = unsafe { Layout::from_size_alignment_unchecked(new_size, alignment) }; + + // SAFETY: + // Two preconditions are guaranteed by the caller: + // * `ptr` is currently allocated with this allocator. + // * `layout` fits the block of memory. + // The size precondition is upheld by selecting between `grow` and `shrink` + // based on the size. + let ptr = unsafe { + if new_size >= layout.size() { + self.grow(ptr, layout, new_layout) + } else { + self.shrink(ptr, layout, new_layout) + } + }; + + match ptr { + Ok(ptr) => ptr.cast().as_ptr(), + Err(AllocError) => ptr::null_mut(), + } + } +} diff --git a/library/core/src/alloc/mod.rs b/library/core/src/alloc/mod.rs index 102fb19efc8ea..b70fd827990a0 100644 --- a/library/core/src/alloc/mod.rs +++ b/library/core/src/alloc/mod.rs @@ -375,6 +375,96 @@ pub const unsafe trait Allocator { } } +/// An [`Allocator`] that can be registered as the standard library’s default +/// through the `#[global_allocator]` attribute. +/// +/// Types implementing this trait can be used as the default allocator for +/// memory allocations through `Box`, `Vec` and the collection types. For +/// instance, the `System` allocator implements this trait, and thus can be +/// explicitly set as the default like so: +/// ``` +/// use std::alloc::System; +/// +/// #[global_allocator] +/// static ALLOCATOR: System = System; +/// ``` +/// +/// The `Global` allocator forwards all memory allocation requests to the +/// `static` annotated with `#[global_allocator]`. Hence, `Global` does not +/// implement `GlobalAllocator` itself, as that would lead to infinite recursion. +/// +/// # Note to implementors +/// +/// This trait is used to prevent the infinite recursion that would occur if the +/// default allocator were to attempt to allocate memory through `Global` (and +/// thus from itself). +/// +/// When to implement this trait: +/// * for custom global allocators that only use system memory allocation +/// services. +/// * for allocators that wrap another allocator that implements `GlobalAllocator`. +/// +/// When **not** to implement this trait: +/// * for wrappers of arbitrary allocators (which might end up being `Global`, +/// leading to infinite recursion). +/// +/// # Safety +/// +/// In addition to the safety requirements of `Allocator`, global allocators are +/// subject to some additional constraints: +/// +/// * It's undefined behavior if global allocators unwind. This restriction may +/// be lifted in the future, but currently a panic from any of these +/// functions may lead to memory unsafety. +/// +/// * You must not rely on allocations actually happening, even if there are explicit +/// heap allocations in the source. The optimizer may detect unused allocations that it can either +/// eliminate entirely or move to the stack and thus never invoke the allocator. The +/// optimizer may further assume that allocation is infallible, so code that used to fail due +/// to allocator failures may now suddenly work because the optimizer worked around the +/// need for an allocation. More concretely, the following code example is unsound, irrespective +/// of whether your custom allocator allows counting how many allocations have happened. +/// +/// ```rust,ignore (unsound and has placeholders) +/// drop(Box::new(42)); +/// let number_of_heap_allocs = /* call private allocator API */; +/// unsafe { std::hint::assert_unchecked(number_of_heap_allocs > 0); } +/// ``` +/// +/// Note that the optimizations mentioned above are not the only +/// optimization that can be applied. You may generally not rely on heap allocations +/// happening if they can be removed without changing program behavior. +/// Whether allocations happen or not is not part of the program behavior, even if it +/// could be detected via an allocator that tracks allocations by printing or otherwise +/// having side effects. +/// +/// # Re-entrance +/// +/// When implementing a global allocator, one has to be careful not to create an infinitely recursive +/// implementation by accident, as many constructs in the Rust standard library may allocate in +/// their implementation. For example, on some platforms, [`std::sync::Mutex`] may allocate, so using +/// it is highly problematic in a global allocator. +/// +/// For this reason, one should generally stick to library features available through +/// [`core`], and avoid using [`std`] in a global allocator. A few features from [`std`] are +/// guaranteed to not use `#[global_allocator]` to allocate: +/// +/// - [`std::thread_local`], +/// - [`std::thread::current`], +/// - [`std::thread::park`] and [`std::thread::Thread`]'s [`unpark`] method and +/// [`Clone`] implementation. +/// +/// [`std`]: ../../std/index.html +/// [`std::sync::Mutex`]: ../../std/sync/struct.Mutex.html +/// [`std::thread_local`]: ../../std/macro.thread_local.html +/// [`std::thread::current`]: ../../std/thread/fn.current.html +/// [`std::thread::park`]: ../../std/thread/fn.park.html +/// [`std::thread::Thread`]: ../../std/thread/struct.Thread.html +/// [`unpark`]: ../../std/thread/struct.Thread.html#method.unpark +#[unstable(feature = "allocator_api", issue = "32838")] +#[expect(multiple_supertrait_upcastable)] +pub unsafe trait GlobalAllocator: Allocator + Sync + 'static {} + #[unstable(feature = "allocator_api", issue = "32838")] #[rustc_const_unstable(feature = "const_heap", issue = "79597")] const unsafe impl Allocator for &A diff --git a/library/std/src/alloc.rs b/library/std/src/alloc.rs index 7a576e083df7c..753ca5aba561c 100644 --- a/library/std/src/alloc.rs +++ b/library/std/src/alloc.rs @@ -63,14 +63,15 @@ #![deny(unsafe_op_in_unsafe_fn)] #![stable(feature = "alloc_module", since = "1.28.0")] -use core::ptr::NonNull; -use core::sync::atomic::{AtomicBool, AtomicPtr, Ordering}; -use core::{hint, mem, ptr}; - #[stable(feature = "alloc_module", since = "1.28.0")] #[doc(inline)] pub use alloc_crate::alloc::*; +use crate::ptr::NonNull; +use crate::sync::atomic::{AtomicBool, AtomicPtr, Ordering}; +use crate::sys::alloc as imp; +use crate::{hint, mem, ptr}; + /// The default memory allocator provided by the operating system. /// /// This is based on `malloc` on Unix platforms and `HeapAlloc` on Windows, @@ -145,11 +146,7 @@ impl System { 0 => Ok(layout.dangling_ptr().cast_slice(0)), // SAFETY: `layout` is non-zero in size, size => unsafe { - let raw_ptr = if zeroed { - GlobalAlloc::alloc_zeroed(self, layout) - } else { - GlobalAlloc::alloc(self, layout) - }; + let raw_ptr = if zeroed { imp::alloc_zeroed(layout) } else { imp::alloc(layout) }; let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?; Ok(ptr.cast_slice(size)) }, @@ -182,7 +179,7 @@ impl System { // `realloc` probably checks for `new_size >= old_layout.size()` or something similar. hint::assert_unchecked(new_size >= old_layout.size()); - let raw_ptr = GlobalAlloc::realloc(self, ptr.as_ptr(), old_layout, new_size); + let raw_ptr = imp::realloc(ptr.as_ptr(), old_layout, new_size); let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?; if zeroed { raw_ptr.add(old_size).write_bytes(0, new_size - old_size); @@ -205,8 +202,8 @@ impl System { } } -// The Allocator impl checks the layout size to be non-zero and forwards to the GlobalAlloc impl, -// which is in `std::sys::*::alloc`. +// The Allocator impl checks the layout size to be non-zero and forwards to the +// platform functions in `std::sys::*::alloc`. #[unstable(feature = "allocator_api", issue = "32838")] unsafe impl Allocator for System { #[inline] @@ -224,7 +221,7 @@ unsafe impl Allocator for System { if layout.size() != 0 { // SAFETY: `layout` is non-zero in size, // other conditions must be upheld by the caller - unsafe { GlobalAlloc::dealloc(self, ptr.as_ptr(), layout) } + unsafe { imp::dealloc(ptr.as_ptr(), layout) } } } @@ -274,7 +271,7 @@ unsafe impl Allocator for System { // `realloc` probably checks for `new_size <= old_layout.size()` or something similar. hint::assert_unchecked(new_size <= old_layout.size()); - let raw_ptr = GlobalAlloc::realloc(self, ptr.as_ptr(), old_layout, new_size); + let raw_ptr = imp::realloc(ptr.as_ptr(), old_layout, new_size); let ptr = NonNull::new(raw_ptr).ok_or(AllocError)?; Ok(ptr.cast_slice(new_size)) }, @@ -294,6 +291,9 @@ unsafe impl Allocator for System { } } +#[unstable(feature = "allocator_api", issue = "32838")] +unsafe impl GlobalAllocator for System {} + static HOOK: AtomicPtr<()> = AtomicPtr::new(ptr::null_mut()); /// Registers a custom allocation error hook, replacing any that was previously registered. @@ -435,7 +435,12 @@ pub fn rust_oom(layout: Layout) -> ! { #[allow(unused_attributes)] #[unstable(feature = "alloc_internals", issue = "none")] pub mod __default_lib_allocator { - use super::{GlobalAlloc, Layout, System}; + use super::Layout; + // We call the system functions directly to avoid any overheads introduced + // by the roundtrip through `impl Allocator for System` and + // `impl GlobalAlloc for A`. + use crate::sys::alloc as imp; + // These magic symbol names are used as a fallback for implementing the // `__rust_alloc` etc symbols (see `src/liballoc/alloc.rs`) when there is // no `#[global_allocator]` attribute. @@ -452,7 +457,7 @@ pub mod __default_lib_allocator { // `GlobalAlloc::alloc`. unsafe { let layout = Layout::from_size_align_unchecked(size, align); - System.alloc(layout) + imp::alloc(layout) } } @@ -460,7 +465,7 @@ pub mod __default_lib_allocator { pub unsafe extern "C" fn __rdl_dealloc(ptr: *mut u8, size: usize, align: usize) { // SAFETY: see the guarantees expected by `Layout::from_size_align` and // `GlobalAlloc::dealloc`. - unsafe { System.dealloc(ptr, Layout::from_size_align_unchecked(size, align)) } + unsafe { imp::dealloc(ptr, Layout::from_size_align_unchecked(size, align)) } } #[rustc_std_internal_symbol] @@ -474,7 +479,7 @@ pub mod __default_lib_allocator { // `GlobalAlloc::realloc`. unsafe { let old_layout = Layout::from_size_align_unchecked(old_size, align); - System.realloc(ptr, old_layout, new_size) + imp::realloc(ptr, old_layout, new_size) } } @@ -484,7 +489,7 @@ pub mod __default_lib_allocator { // `GlobalAlloc::alloc_zeroed`. unsafe { let layout = Layout::from_size_align_unchecked(size, align); - System.alloc_zeroed(layout) + imp::alloc_zeroed(layout) } } } diff --git a/library/std/src/sys/alloc/hermit.rs b/library/std/src/sys/alloc/hermit.rs index 77f8200a70a64..9afcb315f4ab5 100644 --- a/library/std/src/sys/alloc/hermit.rs +++ b/library/std/src/sys/alloc/hermit.rs @@ -1,27 +1,24 @@ -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - let size = layout.size(); - let align = layout.align(); - unsafe { hermit_abi::malloc(size, align) } - } +#[inline] +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + let size = layout.size(); + let align = layout.align(); + unsafe { hermit_abi::malloc(size, align) } +} - #[inline] - unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { - let size = layout.size(); - let align = layout.align(); - unsafe { - hermit_abi::free(ptr, size, align); - } +#[inline] +pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) { + let size = layout.size(); + let align = layout.align(); + unsafe { + hermit_abi::free(ptr, size, align); } +} - #[inline] - unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - let size = layout.size(); - let align = layout.align(); - unsafe { hermit_abi::realloc(ptr, size, align, new_size) } - } +#[inline] +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + let size = layout.size(); + let align = layout.align(); + unsafe { hermit_abi::realloc(ptr, size, align, new_size) } } diff --git a/library/std/src/sys/alloc/mod.rs b/library/std/src/sys/alloc/mod.rs index f2f1d1c7feceb..73d35781f09bf 100644 --- a/library/std/src/sys/alloc/mod.rs +++ b/library/std/src/sys/alloc/mod.rs @@ -1,6 +1,6 @@ #![forbid(unsafe_op_in_unsafe_fn)] -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; use crate::ptr; // The minimum alignment guaranteed by the architecture. This value is used to @@ -47,21 +47,16 @@ const MIN_ALIGN: usize = if cfg!(any( }; #[allow(dead_code)] -unsafe fn realloc_fallback( - alloc: &System, - ptr: *mut u8, - old_layout: Layout, - new_size: usize, -) -> *mut u8 { +unsafe fn realloc_fallback(ptr: *mut u8, old_layout: Layout, new_size: usize) -> *mut u8 { // SAFETY: Docs for GlobalAlloc::realloc require this to be valid unsafe { let new_layout = Layout::from_size_align_unchecked(new_size, old_layout.align()); - let new_ptr = GlobalAlloc::alloc(alloc, new_layout); + let new_ptr = alloc(new_layout); if !new_ptr.is_null() { let size = usize::min(old_layout.size(), new_size); ptr::copy_nonoverlapping(ptr, new_ptr, size); - GlobalAlloc::dealloc(alloc, ptr, old_layout); + dealloc(ptr, old_layout); } new_ptr @@ -76,35 +71,69 @@ cfg_select! { target_os = "trusty", ) => { mod unix; + use unix as imp; } target_os = "windows" => { mod windows; + use windows as imp; } target_os = "hermit" => { mod hermit; + use hermit as imp; } target_os = "motor" => { mod motor; + use motor as imp; } all(target_vendor = "fortanix", target_env = "sgx") => { mod sgx; + use sgx as imp; } target_os = "solid_asp3" => { mod solid; + use solid as imp; } target_os = "uefi" => { mod uefi; + use uefi as imp; } target_os = "vexos" => { mod vexos; + use vexos as imp; } target_family = "wasm" => { mod wasm; + use wasm as imp; } target_os = "xous" => { mod xous; + use xous as imp; } target_os = "zkvm" => { mod zkvm; + use zkvm as imp; + } +} + +pub use imp::{alloc, dealloc, realloc}; + +cfg_select! { + any( + target_os = "hermit", + target_os = "solid_asp3", + target_os = "uefi", + target_os = "zkvm", + ) => { + #[inline] + pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { + let ptr = unsafe { alloc(layout) }; + if !ptr.is_null() { + unsafe { ptr.write_bytes(0, layout.size()) }; + } + ptr + } + } + _ => { + pub use imp::alloc_zeroed; } } diff --git a/library/std/src/sys/alloc/motor.rs b/library/std/src/sys/alloc/motor.rs index 271e3c40c26ae..090dc198bb500 100644 --- a/library/std/src/sys/alloc/motor.rs +++ b/library/std/src/sys/alloc/motor.rs @@ -1,28 +1,13 @@ -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - // SAFETY: same requirements as in GlobalAlloc::alloc. - moto_rt::alloc::alloc(layout) - } - - #[inline] - unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { - // SAFETY: same requirements as in GlobalAlloc::alloc_zeroed. - moto_rt::alloc::alloc_zeroed(layout) - } - - #[inline] - unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { - // SAFETY: same requirements as in GlobalAlloc::dealloc. - unsafe { moto_rt::alloc::dealloc(ptr, layout) } - } +#[inline] +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + moto_rt::alloc::alloc(layout) +} - #[inline] - unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - // SAFETY: same requirements as in GlobalAlloc::realloc. - unsafe { moto_rt::alloc::realloc(ptr, layout, new_size) } - } +#[inline] +pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { + moto_rt::alloc::alloc_zeroed(layout) } + +pub use moto_rt::alloc::{dealloc, realloc}; diff --git a/library/std/src/sys/alloc/sgx.rs b/library/std/src/sys/alloc/sgx.rs index afdef7a5cb647..c20761259048e 100644 --- a/library/std/src/sys/alloc/sgx.rs +++ b/library/std/src/sys/alloc/sgx.rs @@ -1,4 +1,4 @@ -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; use crate::ptr; use crate::sync::atomic::{Atomic, AtomicBool, Ordering}; use crate::sys::pal::abi::mem as sgx_mem; @@ -57,31 +57,28 @@ unsafe impl dlmalloc::Allocator for Sgx { } } -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - // SAFETY: the caller must uphold the safety contract for `malloc` - unsafe { DLMALLOC.lock().malloc(layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + // SAFETY: the caller must uphold the safety contract for `malloc` + unsafe { DLMALLOC.lock().malloc(layout.size(), layout.align()) } +} - #[inline] - unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { - // SAFETY: the caller must uphold the safety contract for `malloc` - unsafe { DLMALLOC.lock().calloc(layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { + // SAFETY: the caller must uphold the safety contract for `malloc` + unsafe { DLMALLOC.lock().calloc(layout.size(), layout.align()) } +} - #[inline] - unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { - // SAFETY: the caller must uphold the safety contract for `malloc` - unsafe { DLMALLOC.lock().free(ptr, layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) { + // SAFETY: the caller must uphold the safety contract for `malloc` + unsafe { DLMALLOC.lock().free(ptr, layout.size(), layout.align()) } +} - #[inline] - unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - // SAFETY: the caller must uphold the safety contract for `malloc` - unsafe { DLMALLOC.lock().realloc(ptr, layout.size(), layout.align(), new_size) } - } +#[inline] +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + // SAFETY: the caller must uphold the safety contract for `malloc` + unsafe { DLMALLOC.lock().realloc(ptr, layout.size(), layout.align(), new_size) } } // The following functions are needed by libunwind. These symbols are named diff --git a/library/std/src/sys/alloc/solid.rs b/library/std/src/sys/alloc/solid.rs index 47cfa2eb1162b..5d3f396f0dd11 100644 --- a/library/std/src/sys/alloc/solid.rs +++ b/library/std/src/sys/alloc/solid.rs @@ -1,30 +1,27 @@ use super::{MIN_ALIGN, realloc_fallback}; -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() { - unsafe { libc::malloc(layout.size()) as *mut u8 } - } else { - unsafe { libc::memalign(layout.align(), layout.size()) as *mut u8 } - } +#[inline] +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() { + unsafe { libc::malloc(layout.size()) as *mut u8 } + } else { + unsafe { libc::memalign(layout.align(), layout.size()) as *mut u8 } } +} - #[inline] - unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) { - unsafe { libc::free(ptr as *mut libc::c_void) } - } +#[inline] +pub unsafe fn dealloc(ptr: *mut u8, _layout: Layout) { + unsafe { libc::free(ptr as *mut libc::c_void) } +} - #[inline] - unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - unsafe { - if layout.align() <= MIN_ALIGN && layout.align() <= new_size { - libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8 - } else { - realloc_fallback(self, ptr, layout, new_size) - } +#[inline] +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + unsafe { + if layout.align() <= MIN_ALIGN && layout.align() <= new_size { + libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8 + } else { + realloc_fallback(ptr, layout, new_size) } } } diff --git a/library/std/src/sys/alloc/uefi.rs b/library/std/src/sys/alloc/uefi.rs index 5221876e90866..aa7fcc9fe110c 100644 --- a/library/std/src/sys/alloc/uefi.rs +++ b/library/std/src/sys/alloc/uefi.rs @@ -3,47 +3,48 @@ use r_efi::protocols::loaded_image; -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; use crate::sync::OnceLock; use crate::sys::pal::helpers; -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - static EFI_MEMORY_TYPE: OnceLock = OnceLock::new(); - - // Return null pointer if boot services are not available - if crate::os::uefi::env::boot_services().is_none() { - return crate::ptr::null_mut(); - } - - // If boot services is valid then SystemTable is not null. - let system_table = crate::os::uefi::env::system_table().as_ptr().cast(); - - // Each loaded image has an image handle that supports `EFI_LOADED_IMAGE_PROTOCOL`. Thus, this - // will never fail. - let mem_type = EFI_MEMORY_TYPE.get_or_init(|| { - let protocol = helpers::image_handle_protocol::( - loaded_image::PROTOCOL_GUID, - ) - .unwrap(); - // Gives allocations the memory type that the data sections were loaded as. - unsafe { (*protocol.as_ptr()).image_data_type } - }); - - // The caller must ensure non-0 layout - unsafe { r_efi_alloc::raw::alloc(system_table, layout, *mem_type) } +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + static EFI_MEMORY_TYPE: OnceLock = OnceLock::new(); + + // Return null pointer if boot services are not available + if crate::os::uefi::env::boot_services().is_none() { + return crate::ptr::null_mut(); } - unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { - // Do nothing if boot services are not available - if crate::os::uefi::env::boot_services().is_none() { - return; - } + // If boot services is valid then SystemTable is not null. + let system_table = crate::os::uefi::env::system_table().as_ptr().cast(); + + // Each loaded image has an image handle that supports `EFI_LOADED_IMAGE_PROTOCOL`. Thus, this + // will never fail. + let mem_type = EFI_MEMORY_TYPE.get_or_init(|| { + let protocol = + helpers::image_handle_protocol::(loaded_image::PROTOCOL_GUID) + .unwrap(); + // Gives allocations the memory type that the data sections were loaded as. + unsafe { (*protocol.as_ptr()).image_data_type } + }); + + // The caller must ensure non-0 layout + unsafe { r_efi_alloc::raw::alloc(system_table, layout, *mem_type) } +} - // If boot services is valid then SystemTable is not null. - let system_table = crate::os::uefi::env::system_table().as_ptr().cast(); - // The caller must ensure non-0 layout - unsafe { r_efi_alloc::raw::dealloc(system_table, ptr, layout) } +pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) { + // Do nothing if boot services are not available + if crate::os::uefi::env::boot_services().is_none() { + return; } + + // If boot services is valid then SystemTable is not null. + let system_table = crate::os::uefi::env::system_table().as_ptr().cast(); + // The caller must ensure non-0 layout + unsafe { r_efi_alloc::raw::dealloc(system_table, ptr, layout) } +} + +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + // SAFETY: this is just a `pub` wrapper. + unsafe { super::realloc_fallback(ptr, layout, new_size) } } diff --git a/library/std/src/sys/alloc/unix.rs b/library/std/src/sys/alloc/unix.rs index 3d369b08abc77..d6de8bf28c44c 100644 --- a/library/std/src/sys/alloc/unix.rs +++ b/library/std/src/sys/alloc/unix.rs @@ -1,60 +1,57 @@ use super::{MIN_ALIGN, realloc_fallback}; -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; use crate::ptr; -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - // jemalloc provides alignment less than MIN_ALIGN for small allocations. - // So only rely on MIN_ALIGN if size >= align. - // Also see and - // . - if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() { - unsafe { libc::malloc(layout.size()) as *mut u8 } - } else { - // `posix_memalign` returns a non-aligned value if supplied a very - // large alignment on older versions of Apple's platforms (unknown - // exactly which version range, but the issue is definitely - // present in macOS 10.14 and iOS 13.3). - // - // - #[cfg(target_vendor = "apple")] - { - if layout.align() > (1 << 31) { - return ptr::null_mut(); - } +#[inline] +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + // jemalloc provides alignment less than MIN_ALIGN for small allocations. + // So only rely on MIN_ALIGN if size >= align. + // Also see and + // . + if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() { + unsafe { libc::malloc(layout.size()) as *mut u8 } + } else { + // `posix_memalign` returns a non-aligned value if supplied a very + // large alignment on older versions of Apple's platforms (unknown + // exactly which version range, but the issue is definitely + // present in macOS 10.14 and iOS 13.3). + // + // + #[cfg(target_vendor = "apple")] + { + if layout.align() > (1 << 31) { + return ptr::null_mut(); } - unsafe { aligned_malloc(&layout) } } + unsafe { aligned_malloc(&layout) } } +} - #[inline] - unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { - // See the comment above in `alloc` for why this check looks the way it does. - if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() { - unsafe { libc::calloc(layout.size(), 1) as *mut u8 } - } else { - let ptr = unsafe { self.alloc(layout) }; - if !ptr.is_null() { - unsafe { ptr::write_bytes(ptr, 0, layout.size()) }; - } - ptr +#[inline] +pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { + // See the comment above in `alloc` for why this check looks the way it does. + if layout.align() <= MIN_ALIGN && layout.align() <= layout.size() { + unsafe { libc::calloc(layout.size(), 1) as *mut u8 } + } else { + let ptr = unsafe { alloc(layout) }; + if !ptr.is_null() { + unsafe { ptr::write_bytes(ptr, 0, layout.size()) }; } + ptr } +} - #[inline] - unsafe fn dealloc(&self, ptr: *mut u8, _layout: Layout) { - unsafe { libc::free(ptr as *mut libc::c_void) } - } +#[inline] +pub unsafe fn dealloc(ptr: *mut u8, _layout: Layout) { + unsafe { libc::free(ptr as *mut libc::c_void) } +} - #[inline] - unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - if layout.align() <= MIN_ALIGN && layout.align() <= new_size { - unsafe { libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8 } - } else { - unsafe { realloc_fallback(self, ptr, layout, new_size) } - } +#[inline] +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + if layout.align() <= MIN_ALIGN && layout.align() <= new_size { + unsafe { libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8 } + } else { + unsafe { realloc_fallback(ptr, layout, new_size) } } } diff --git a/library/std/src/sys/alloc/vexos.rs b/library/std/src/sys/alloc/vexos.rs index c1fb6896a89ae..481462296f8af 100644 --- a/library/std/src/sys/alloc/vexos.rs +++ b/library/std/src/sys/alloc/vexos.rs @@ -1,7 +1,7 @@ // FIXME(static_mut_refs): Do not allow `static_mut_refs` lint #![allow(static_mut_refs)] -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; use crate::ptr; use crate::sync::atomic::{AtomicBool, Ordering}; @@ -60,37 +60,34 @@ unsafe impl dlmalloc::Allocator for Vexos { } } -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which - // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used. - // Calling malloc() is safe because preconditions on this function match the trait method preconditions. - unsafe { DLMALLOC.malloc(layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which + // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used. + // Calling malloc() is safe because preconditions on this function match the trait method preconditions. + unsafe { DLMALLOC.malloc(layout.size(), layout.align()) } +} - #[inline] - unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { - // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which - // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used. - // Calling calloc() is safe because preconditions on this function match the trait method preconditions. - unsafe { DLMALLOC.calloc(layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { + // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which + // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used. + // Calling calloc() is safe because preconditions on this function match the trait method preconditions. + unsafe { DLMALLOC.calloc(layout.size(), layout.align()) } +} - #[inline] - unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { - // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which - // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used. - // Calling free() is safe because preconditions on this function match the trait method preconditions. - unsafe { DLMALLOC.free(ptr, layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) { + // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which + // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used. + // Calling free() is safe because preconditions on this function match the trait method preconditions. + unsafe { DLMALLOC.free(ptr, layout.size(), layout.align()) } +} - #[inline] - unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which - // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used. - // Calling realloc() is safe because preconditions on this function match the trait method preconditions. - unsafe { DLMALLOC.realloc(ptr, layout.size(), layout.align(), new_size) } - } +#[inline] +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + // SAFETY: DLMALLOC access is guaranteed to be safe because we are a single-threaded target, which + // guarantees unique and non-reentrant access to the allocator. As such, no allocator lock is used. + // Calling realloc() is safe because preconditions on this function match the trait method preconditions. + unsafe { DLMALLOC.realloc(ptr, layout.size(), layout.align(), new_size) } } diff --git a/library/std/src/sys/alloc/wasm.rs b/library/std/src/sys/alloc/wasm.rs index 48e2fdd4eccec..995230aebaa01 100644 --- a/library/std/src/sys/alloc/wasm.rs +++ b/library/std/src/sys/alloc/wasm.rs @@ -18,7 +18,7 @@ use core::cell::SyncUnsafeCell; -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; struct SyncDlmalloc(dlmalloc::Dlmalloc); unsafe impl Sync for SyncDlmalloc {} @@ -26,39 +26,36 @@ unsafe impl Sync for SyncDlmalloc {} static DLMALLOC: SyncUnsafeCell = SyncUnsafeCell::new(SyncDlmalloc(dlmalloc::Dlmalloc::new())); -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. - // Calling malloc() is safe because preconditions on this function match the trait method preconditions. - let _lock = lock::lock(); - unsafe { (*DLMALLOC.get()).0.malloc(layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. + // Calling malloc() is safe because preconditions on this function match the trait method preconditions. + let _lock = lock::lock(); + unsafe { (*DLMALLOC.get()).0.malloc(layout.size(), layout.align()) } +} - #[inline] - unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { - // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. - // Calling calloc() is safe because preconditions on this function match the trait method preconditions. - let _lock = lock::lock(); - unsafe { (*DLMALLOC.get()).0.calloc(layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { + // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. + // Calling calloc() is safe because preconditions on this function match the trait method preconditions. + let _lock = lock::lock(); + unsafe { (*DLMALLOC.get()).0.calloc(layout.size(), layout.align()) } +} - #[inline] - unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { - // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. - // Calling free() is safe because preconditions on this function match the trait method preconditions. - let _lock = lock::lock(); - unsafe { (*DLMALLOC.get()).0.free(ptr, layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) { + // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. + // Calling free() is safe because preconditions on this function match the trait method preconditions. + let _lock = lock::lock(); + unsafe { (*DLMALLOC.get()).0.free(ptr, layout.size(), layout.align()) } +} - #[inline] - unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. - // Calling realloc() is safe because preconditions on this function match the trait method preconditions. - let _lock = lock::lock(); - unsafe { (*DLMALLOC.get()).0.realloc(ptr, layout.size(), layout.align(), new_size) } - } +#[inline] +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. + // Calling realloc() is safe because preconditions on this function match the trait method preconditions. + let _lock = lock::lock(); + unsafe { (*DLMALLOC.get()).0.realloc(ptr, layout.size(), layout.align(), new_size) } } #[cfg(target_feature = "atomics")] diff --git a/library/std/src/sys/alloc/windows.rs b/library/std/src/sys/alloc/windows.rs index 9336a6ec085aa..1d75cbd9d54f1 100644 --- a/library/std/src/sys/alloc/windows.rs +++ b/library/std/src/sys/alloc/windows.rs @@ -1,5 +1,18 @@ +//! Implements `System` on Windows. +//! +//! All pointers returned by this allocator have, in addition to the guarantees of `GlobalAlloc`, the +//! following properties: +//! +//! If the pointer was allocated or reallocated with a `layout` specifying an alignment <= `MIN_ALIGN` +//! the pointer will be aligned to at least `MIN_ALIGN` and point to the start of the allocated block. +//! +//! If the pointer was allocated or reallocated with a `layout` specifying an alignment > `MIN_ALIGN` +//! the pointer will be aligned to the specified alignment and not point to the start of the allocated block. +//! Instead there will be a header readable directly before the returned pointer, containing the actual +//! location of the start of the block. + use super::{MIN_ALIGN, realloc_fallback}; -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; use crate::ffi::c_void; use crate::mem::MaybeUninit; use crate::ptr; @@ -150,70 +163,56 @@ unsafe fn allocate(layout: Layout, zeroed: bool) -> *mut u8 { } } -// All pointers returned by this allocator have, in addition to the guarantees of `GlobalAlloc`, the -// following properties: -// -// If the pointer was allocated or reallocated with a `layout` specifying an alignment <= `MIN_ALIGN` -// the pointer will be aligned to at least `MIN_ALIGN` and point to the start of the allocated block. -// -// If the pointer was allocated or reallocated with a `layout` specifying an alignment > `MIN_ALIGN` -// the pointer will be aligned to the specified alignment and not point to the start of the allocated block. -// Instead there will be a header readable directly before the returned pointer, containing the actual -// location of the start of the block. -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - // SAFETY: Pointers returned by `allocate` satisfy the guarantees of `System` - let zeroed = false; - unsafe { allocate(layout, zeroed) } - } +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + // SAFETY: Pointers returned by `allocate` satisfy the guarantees of `System` + let zeroed = false; + unsafe { allocate(layout, zeroed) } +} - #[inline] - unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { - // SAFETY: Pointers returned by `allocate` satisfy the guarantees of `System` - let zeroed = true; - unsafe { allocate(layout, zeroed) } - } +#[inline] +pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { + // SAFETY: Pointers returned by `allocate` satisfy the guarantees of `System` + let zeroed = true; + unsafe { allocate(layout, zeroed) } +} - #[inline] - unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { - let block = { - if layout.align() <= MIN_ALIGN { - ptr - } else { - // The location of the start of the block is stored in the padding before `ptr`. +#[inline] +pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) { + let block = { + if layout.align() <= MIN_ALIGN { + ptr + } else { + // The location of the start of the block is stored in the padding before `ptr`. - // SAFETY: Because of the contract of `System`, `ptr` is guaranteed to be non-null - // and have a header readable directly before it. - unsafe { ptr::read((ptr as *mut Header).sub(1)).0 } - } - }; + // SAFETY: Because of the contract of `System`, `ptr` is guaranteed to be non-null + // and have a header readable directly before it. + unsafe { ptr::read((ptr as *mut Header).sub(1)).0 } + } + }; + // because `ptr` has been successfully allocated with this allocator, + // there must be a valid process heap. + let heap = get_process_heap(); + + // SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`, + // `block` is a pointer to the start of an allocated block. + unsafe { HeapFree(heap, 0, block.cast::()) }; +} + +#[inline] +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + if layout.align() <= MIN_ALIGN { // because `ptr` has been successfully allocated with this allocator, // there must be a valid process heap. let heap = get_process_heap(); // SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`, - // `block` is a pointer to the start of an allocated block. - unsafe { HeapFree(heap, 0, block.cast::()) }; - } - - #[inline] - unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - if layout.align() <= MIN_ALIGN { - // because `ptr` has been successfully allocated with this allocator, - // there must be a valid process heap. - let heap = get_process_heap(); - - // SAFETY: `heap` is a non-null handle returned by `GetProcessHeap`, - // `ptr` is a pointer to the start of an allocated block. - // The returned pointer points to the start of an allocated block. - unsafe { HeapReAlloc(heap, 0, ptr.cast::(), new_size).cast::() } - } else { - // SAFETY: `realloc_fallback` is implemented using `dealloc` and `alloc`, which will - // correctly handle `ptr` and return a pointer satisfying the guarantees of `System` - unsafe { realloc_fallback(self, ptr, layout, new_size) } - } + // `ptr` is a pointer to the start of an allocated block. + // The returned pointer points to the start of an allocated block. + unsafe { HeapReAlloc(heap, 0, ptr.cast::(), new_size).cast::() } + } else { + // SAFETY: `realloc_fallback` is implemented using `dealloc` and `alloc`, which will + // correctly handle `ptr` and return a pointer satisfying the guarantees of `System` + unsafe { realloc_fallback(ptr, layout, new_size) } } } diff --git a/library/std/src/sys/alloc/xous.rs b/library/std/src/sys/alloc/xous.rs index c7f973b802791..7a4fc5e9a873f 100644 --- a/library/std/src/sys/alloc/xous.rs +++ b/library/std/src/sys/alloc/xous.rs @@ -1,7 +1,7 @@ // FIXME(static_mut_refs): Do not allow `static_mut_refs` lint #![allow(static_mut_refs)] -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; #[cfg(not(test))] #[unsafe(export_name = "_ZN16__rust_internals3std3sys4xous5alloc8DLMALLOCE")] @@ -13,39 +13,36 @@ unsafe extern "Rust" { static mut DLMALLOC: dlmalloc::Dlmalloc; } -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. - // Calling malloc() is safe because preconditions on this function match the trait method preconditions. - let _lock = lock::lock(); - unsafe { DLMALLOC.malloc(layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. + // Calling malloc() is safe because preconditions on this function match the trait method preconditions. + let _lock = lock::lock(); + unsafe { DLMALLOC.malloc(layout.size(), layout.align()) } +} - #[inline] - unsafe fn alloc_zeroed(&self, layout: Layout) -> *mut u8 { - // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. - // Calling calloc() is safe because preconditions on this function match the trait method preconditions. - let _lock = lock::lock(); - unsafe { DLMALLOC.calloc(layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 { + // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. + // Calling calloc() is safe because preconditions on this function match the trait method preconditions. + let _lock = lock::lock(); + unsafe { DLMALLOC.calloc(layout.size(), layout.align()) } +} - #[inline] - unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) { - // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. - // Calling free() is safe because preconditions on this function match the trait method preconditions. - let _lock = lock::lock(); - unsafe { DLMALLOC.free(ptr, layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn dealloc(ptr: *mut u8, layout: Layout) { + // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. + // Calling free() is safe because preconditions on this function match the trait method preconditions. + let _lock = lock::lock(); + unsafe { DLMALLOC.free(ptr, layout.size(), layout.align()) } +} - #[inline] - unsafe fn realloc(&self, ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { - // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. - // Calling realloc() is safe because preconditions on this function match the trait method preconditions. - let _lock = lock::lock(); - unsafe { DLMALLOC.realloc(ptr, layout.size(), layout.align(), new_size) } - } +#[inline] +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + // SAFETY: DLMALLOC access is guaranteed to be safe because the lock gives us unique and non-reentrant access. + // Calling realloc() is safe because preconditions on this function match the trait method preconditions. + let _lock = lock::lock(); + unsafe { DLMALLOC.realloc(ptr, layout.size(), layout.align(), new_size) } } mod lock { diff --git a/library/std/src/sys/alloc/zkvm.rs b/library/std/src/sys/alloc/zkvm.rs index a600cfa2220dd..7f39d7fed777e 100644 --- a/library/std/src/sys/alloc/zkvm.rs +++ b/library/std/src/sys/alloc/zkvm.rs @@ -1,15 +1,18 @@ -use crate::alloc::{GlobalAlloc, Layout, System}; +use crate::alloc::Layout; use crate::sys::pal::abi; -#[stable(feature = "alloc_system_type", since = "1.28.0")] -unsafe impl GlobalAlloc for System { - #[inline] - unsafe fn alloc(&self, layout: Layout) -> *mut u8 { - unsafe { abi::sys_alloc_aligned(layout.size(), layout.align()) } - } +#[inline] +pub unsafe fn alloc(layout: Layout) -> *mut u8 { + unsafe { abi::sys_alloc_aligned(layout.size(), layout.align()) } +} + +#[inline] +pub unsafe fn dealloc(_ptr: *mut u8, _layout: Layout) { + // this allocator never deallocates memory +} - #[inline] - unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) { - // this allocator never deallocates memory - } +#[inline] +pub unsafe fn realloc(ptr: *mut u8, layout: Layout, new_size: usize) -> *mut u8 { + // SAFETY: this is just a `pub` wrapper. + unsafe { super::realloc_fallback(ptr, layout, new_size) } } diff --git a/library/std/src/sys/mod.rs b/library/std/src/sys/mod.rs index fe0c103952414..58c8dc43e12ae 100644 --- a/library/std/src/sys/mod.rs +++ b/library/std/src/sys/mod.rs @@ -1,11 +1,11 @@ #![allow(unsafe_op_in_unsafe_fn)] -mod alloc; mod configure_builtins; mod helpers; mod pal; mod personality; +pub mod alloc; pub mod args; pub mod backtrace; pub mod cmath; diff --git a/src/tools/miri/tests/fail/alloc/global_system_mixup.stderr b/src/tools/miri/tests/fail/alloc/global_system_mixup.stderr index 1e9d859b5cf81..1853ecbf43c70 100644 --- a/src/tools/miri/tests/fail/alloc/global_system_mixup.stderr +++ b/src/tools/miri/tests/fail/alloc/global_system_mixup.stderr @@ -1,13 +1,13 @@ error: Undefined Behavior: deallocating ALLOC, which is Rust heap memory, using PLATFORM heap deallocation operation --> RUSTLIB/std/src/sys/alloc/PLATFORM.rs:LL:CC | -LL | FREE(); +LL | FREE(); | ^ Undefined Behavior occurred here | = help: this indicates a bug in the program: it performed an invalid operation, and caused Undefined Behavior = help: see https://doc.rust-lang.org/nightly/reference/behavior-considered-undefined.html for further information = note: stack backtrace: - 0: std::sys::alloc::PLATFORM::::dealloc + 0: std::sys::alloc::PLATFORM::dealloc at RUSTLIB/std/src/sys/alloc/PLATFORM.rs:LL:CC 1: ::deallocate at RUSTLIB/std/src/alloc.rs:LL:CC diff --git a/tests/ui/allocator/not-an-allocator.u.stderr b/tests/ui/allocator/not-an-allocator.u.stderr index f7400d16b1fd1..9be5dd495db02 100644 --- a/tests/ui/allocator/not-an-allocator.u.stderr +++ b/tests/ui/allocator/not-an-allocator.u.stderr @@ -4,10 +4,11 @@ error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied LL | #[global_allocator] | ------------------- in this attribute macro expansion LL | static A: usize = 0; - | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize` + | ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize` | -help: the trait `GlobalAlloc` is implemented for `System` - --> $SRC_DIR/std/src/sys/alloc/unix.rs:LL:COL +help: the trait `GlobalAllocator` is implemented for `System` + --> $SRC_DIR/std/src/alloc.rs:LL:COL + = note: required for `usize` to implement `GlobalAlloc` error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied --> $DIR/not-an-allocator.rs:5:11 @@ -15,10 +16,11 @@ error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied LL | #[global_allocator] | ------------------- in this attribute macro expansion LL | static A: usize = 0; - | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize` + | ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize` | -help: the trait `GlobalAlloc` is implemented for `System` - --> $SRC_DIR/std/src/sys/alloc/unix.rs:LL:COL +help: the trait `GlobalAllocator` is implemented for `System` + --> $SRC_DIR/std/src/alloc.rs:LL:COL + = note: required for `usize` to implement `GlobalAlloc` = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no` error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied @@ -27,10 +29,11 @@ error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied LL | #[global_allocator] | ------------------- in this attribute macro expansion LL | static A: usize = 0; - | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize` + | ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize` | -help: the trait `GlobalAlloc` is implemented for `System` - --> $SRC_DIR/std/src/sys/alloc/unix.rs:LL:COL +help: the trait `GlobalAllocator` is implemented for `System` + --> $SRC_DIR/std/src/alloc.rs:LL:COL + = note: required for `usize` to implement `GlobalAlloc` = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no` error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied @@ -39,10 +42,11 @@ error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied LL | #[global_allocator] | ------------------- in this attribute macro expansion LL | static A: usize = 0; - | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize` + | ^^^^^ the nightly-only, unstable trait `GlobalAllocator` is not implemented for `usize` | -help: the trait `GlobalAlloc` is implemented for `System` - --> $SRC_DIR/std/src/sys/alloc/unix.rs:LL:COL +help: the trait `GlobalAllocator` is implemented for `System` + --> $SRC_DIR/std/src/alloc.rs:LL:COL + = note: required for `usize` to implement `GlobalAlloc` = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no` error: aborting due to 4 previous errors