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Refactor preemption-related code in OSTD

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This commit is contained in:
jellllly420
2024-08-15 19:36:46 +08:00
committed by Tate, Hongliang Tian
parent f5464e82c0
commit 2ab4ba11bc
7 changed files with 132 additions and 144 deletions
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29
ostd/src/cpu/local/mod.rs
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@ -59,17 +59,6 @@ extern "C" {
fn __cpu_local_end();
}
cpu_local_cell! {
/// A 4-byte preemption information consisting of a should_preempt flag at
/// the highest bit and a preemption counter in the lower 31 bits.
///
/// We need to access the preemption info before we can copy the section
/// for application processors. So, the preemption info is not copied from
/// bootstrap processor's section as the initialization. Instead it is
/// initialized to zero for application processors.
pub(crate) static PREEMPT_INFO: u32 = 0;
}
/// Sets the base address of the CPU-local storage for the bootstrap processor.
///
/// It should be called early to let [`crate::task::disable_preempt`] work,
@ -134,24 +123,6 @@ pub unsafe fn init_on_bsp() {
(ap_pages_ptr as *mut u32).write(cpu_i);
}
// SAFETY: the `PREEMPT_INFO` may be dirty on the BSP, so we need
// to ensure that it is initialized to zero for APs. The safety
// requirements are met since the static is defined in the `.cpu_local`
// section and the pointer to that static is the offset in the CPU-
// local area. It is a `usize` so it is safe to be overwritten.
unsafe {
let preempt_info_ptr = &PREEMPT_INFO as *const _ as usize;
let preempt_info_offset = preempt_info_ptr - __cpu_local_start as usize;
let ap_preempt_info_ptr = ap_pages_ptr.add(preempt_info_offset) as *mut usize;
ap_preempt_info_ptr.write(0);
}
// SAFETY: bytes `8:16` are reserved for storing the pointer to the
// current task. We initialize it to null.
unsafe {
(ap_pages_ptr as *mut u64).add(1).write(0);
}
cpu_local_storages.push(ap_pages);
}