refactor: 启动时同步 clint 初始化

Signed-off-by: YdrMaster <[email protected]>

Author: YdrMaster

rustsbi-qemu/src/clint.rs

@@ -1,18 +1,17 @@
 use crate::{hart_id, trap_stack::remote_hsm};
 use aclint::SifiveClint;
-use core::{mem::MaybeUninit, ptr::NonNull};
+use core::{
+    ptr::null_mut,
+    sync::atomic::{AtomicPtr, Ordering},
+};
 use rustsbi::{spec::binary::SbiRet, HartMask, Ipi, Timer};
 
 pub(crate) struct Clint;
 
-pub(crate) static mut CLINT: MaybeUninit<NonNull<SifiveClint>> = MaybeUninit::uninit();
+pub(crate) static CLINT: AtomicPtr<SifiveClint> = AtomicPtr::new(null_mut());
 
 pub(crate) fn init(base: usize) {
-    unsafe {
-        CLINT
-            .as_mut_ptr()
-            .write_volatile(NonNull::new(base as _).unwrap())
-    }
+    CLINT.store(base as _, Ordering::Release);
 }
 
 impl Ipi for Clint {
@@ -32,24 +31,25 @@ impl Timer for Clint {
     fn set_timer(&self, time_value: u64) {
         unsafe {
             riscv::register::mip::clear_stimer();
-            clint().write_mtimecmp(hart_id(), time_value);
+            (*CLINT.load(Ordering::Relaxed)).write_mtimecmp(hart_id(), time_value);
         }
     }
 }
 
-#[inline]
-fn clint() -> &'static SifiveClint {
-    unsafe { CLINT.as_ptr().read_volatile().as_ref() }
-}
-
 #[inline]
 pub fn set_msip(hart_idx: usize) {
-    clint().set_msip(hart_idx);
+    unsafe { &*CLINT.load(Ordering::Relaxed) }.set_msip(hart_idx);
 }
 
 #[inline]
 pub fn clear() {
-    let clint = clint();
-    clint.clear_msip(hart_id());
-    clint.write_mtimecmp(hart_id(), u64::MAX);
+    loop {
+        if let Some(clint) = unsafe { CLINT.load(Ordering::Relaxed).as_ref() } {
+            clint.clear_msip(hart_id());
+            clint.write_mtimecmp(hart_id(), u64::MAX);
+            break;
+        } else {
+            continue;
+        }
+    }
 }

rustsbi-qemu/src/main.rs

@@ -68,7 +68,6 @@ unsafe extern "C" fn _stop() -> ! {
 /// rust 入口。
 extern "C" fn rust_main(hartid: usize, opaque: usize) {
     static GENESIS: AtomicBool = AtomicBool::new(true);
-    static DONE: AtomicBool = AtomicBool::new(true);
     static BOARD_INFO: Once<BoardInfo> = Once::new();
 
     // 全局初始化过程
@@ -130,15 +129,11 @@ extern "C" fn rust_main(hartid: usize, opaque: usize) {
             start_addr: SUPERVISOR_ENTRY,
             opaque,
         });
-        DONE.store(false, Ordering::SeqCst);
     } else {
         // 设置 pmp
         set_pmp(BOARD_INFO.wait());
         // 设置陷入栈
         trap_stack::prepare_for_trap();
-        while DONE.load(Ordering::SeqCst) {
-            core::hint::spin_loop();
-        }
     }
     // 清理 clint
     clint::clear();

rustsbi-qemu/src/trap_vec.rs

@@ -1,3 +1,4 @@
+use crate::clint::CLINT;
 use aclint::SifiveClint as Clint;
 use core::arch::asm;
 use fast_trap::trap_entry;
@@ -63,7 +64,7 @@ unsafe extern "C" fn mtimer() {
         "   la    a0, {clint_ptr}
             ld    a0, (a0)
             csrr  a1, mhartid
-            li    a2, {u64_max}
+            addi  a2, zero, -1
             call  {set_mtimecmp}
         ",
         // 设置 stip
@@ -83,9 +84,8 @@ unsafe extern "C" fn mtimer() {
         "   csrrw sp, mscratch, sp",
         // 返回
         "   mret",
-        u64_max      = const u64::MAX,
         mip_stip     = const 1 << 5,
-        clint_ptr    =   sym crate::clint::CLINT,
+        clint_ptr    =   sym CLINT,
         //                   Clint::write_mtimecmp_naked(&self, hart_idx, val)
         set_mtimecmp =   sym Clint::write_mtimecmp_naked,
         options(noreturn)
@@ -129,7 +129,7 @@ unsafe extern "C" fn msoft() {
         "   csrrw sp, mscratch, sp",
         // 返回
         "   mret",
-        clint_ptr  = sym crate::clint::CLINT,
+        clint_ptr  = sym CLINT,
         //               Clint::clear_msip_naked(&self, hart_idx)
         clear_msip = sym Clint::clear_msip_naked,
         options(noreturn)