An x86_64 UEFI operating system.
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use alloc::alloc::GlobalAlloc;
use core::alloc::Layout;
use uefi::prelude::{Boot, SystemTable};
use uefi::table::boot::{AllocateType, MemoryType};
/// **This allocator only supports page-level granularity.**
/// Be careful not to use it for small allocations.
/// In particular, it should only be used to allocate data structures
/// for the purpose of setting up another, better allocator.
pub struct UefiAllocator {
// We must directly store an owned system table because:
// 1. It is impossible to take ownership of ST boot services, and
// 2. we cannot store a reference to *anything* here
// because the global allocator has to be static even if we know it's really not.
st: SystemTable<Boot>,
}
impl UefiAllocator {
pub fn new(st: SystemTable<Boot>) -> UefiAllocator {
UefiAllocator { st }
}
}
const PAGE_SIZE: usize = 4096;
unsafe impl GlobalAlloc for UefiAllocator {
unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
self.st.boot_services()
.allocate_pages(AllocateType::AnyPages, MemoryType::LOADER_DATA,
num_integer::div_ceil(layout.size(), PAGE_SIZE))
.expect("Failed to allocate memory!")
as *mut u8
}
unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
self.st.boot_services().free_pages(ptr as u64, num_integer::div_ceil(layout.size(), PAGE_SIZE))
.expect("Failed to free memory!");
}
}