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CpuLocalCell::as_ptr_mut should be safe

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This commit is contained in:
Ruihan Li
2024-11-20 09:43:15 +08:00
committed by Tate, Hongliang Tian
parent 3d63ed7a4c
commit b6944e48bd
2 changed files with 15 additions and 10 deletions
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21
ostd/src/cpu/local/cell.rs
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@ -79,7 +79,7 @@ macro_rules! cpu_local_cell {
pub struct CpuLocalCell<T: 'static>(UnsafeCell<T>);
impl<T: 'static> CpuLocalCell<T> {
/// Initialize a CPU-local object.
/// Initializes a CPU-local object.
///
/// Please do not call this function directly. Instead, use the
/// `cpu_local!` macro.
@ -94,17 +94,22 @@ impl<T: 'static> CpuLocalCell<T> {
Self(UnsafeCell::new(val))
}
/// Get access to the underlying value through a raw pointer.
/// Gets access to the underlying value through a raw pointer.
///
/// This function calculates the virtual address of the CPU-local object
/// based on the CPU-local base address and the offset in the BSP.
///
/// # Safety
///
/// The caller should ensure that within the entire execution of this
/// function, no interrupt or preemption can occur. Otherwise, the
/// returned pointer may points to the variable in another CPU.
pub unsafe fn as_ptr_mut(&'static self) -> *mut T {
/// This method is safe, but using the returned pointer will be unsafe.
/// Specifically,
/// - Preemption should be disabled from the time this method is called
/// to the time the pointer is used. Otherwise, the pointer may point
/// to the variable on another CPU, making it difficult or impossible
/// to determine if the data can be borrowed.
/// - If the variable can be used in interrupt handlers, borrowing the
/// data should be done with interrupts disabled. Otherwise, more care
/// must be taken to ensure that the borrowing rules are correctly
/// enforced, since the interrupts may come asynchronously.
pub fn as_ptr_mut(&'static self) -> *mut T {
super::has_init::assert_true();
let offset = {