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22 changes: 19 additions & 3 deletions library/std/src/sys/uefi/alloc.rs
Original file line number Diff line number Diff line change
@@ -1,22 +1,38 @@
//! Global Allocator for UEFI.
//! Uses [r-efi-alloc](https://crates.io/crates/r-efi-alloc)

use crate::alloc::{GlobalAlloc, Layout, System};
use r_efi::protocols::loaded_image;

const MEMORY_TYPE: u32 = r_efi::efi::LOADER_DATA;
use crate::alloc::{GlobalAlloc, Layout, System};
use crate::sync::OnceLock;
use crate::sys::uefi::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<u32> = 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>(
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, MEMORY_TYPE) }
unsafe { r_efi_alloc::raw::alloc(system_table, layout, *mem_type) }
}

unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
Expand Down