Fix SoftIRQ initialization requirements for SMP

ostd/src/boot/smp.rs

@@ -15,7 +15,6 @@ use crate::{
         page::{self, meta::KernelMeta, ContPages},
         PAGE_SIZE,
     },
-    trap,
 };
 
 pub(crate) static AP_BOOT_INFO: Once<ApBootInfo> = Once::new();
@@ -120,7 +119,10 @@ fn ap_early_entry(local_apic_id: u32) -> ! {
         cpu::set_this_cpu_id(local_apic_id);
     }
 
-    trap::init();
+    // SAFETY: this function is only called once on this AP.
+    unsafe {
+        trapframe::init();
+    }
     crate::arch::irq::enable_local();
 
     // Mark the AP as started.

ostd/src/lib.rs

@@ -86,7 +86,9 @@ pub unsafe fn init() {
     mm::kspace::init_kernel_page_table(mm::init_page_meta());
     mm::misc_init();
 
-    trap::init();
+    trapframe::init();
+    // SAFETY: This function is called only once in the entire system.
+    unsafe { trap::softirq::init() };
     arch::init_on_bsp();
 
     bus::init();

ostd/src/trap/mod.rs

@@ -12,10 +12,3 @@ pub use trapframe::TrapFrame;
 
 pub(crate) use self::handler::call_irq_callback_functions;
 pub use self::irq::{disable_local, DisabledLocalIrqGuard, IrqCallbackFunction, IrqLine};
-
-pub(crate) fn init() {
-    unsafe {
-        trapframe::init();
-    }
-    softirq::init();
-}

ostd/src/trap/softirq.rs

@@ -95,9 +95,14 @@ impl SoftIrqLine {
 /// A slice that stores the [`SoftIrqLine`]s, whose ID is equal to its offset in the slice.
 static LINES: Once<[SoftIrqLine; SoftIrqLine::NR_LINES as usize]> = Once::new();
 
-pub(super) fn init() {
+/// Initializes the softirq lines.
+///
+/// # Safety
+///
+/// This function must be called only once.
+pub unsafe fn init() {
     let lines: [SoftIrqLine; SoftIrqLine::NR_LINES as usize] =
-        array_init::array_init(|i| SoftIrqLine::new(i as u8));
+        core::array::from_fn(|i| SoftIrqLine::new(i as u8));
     LINES.call_once(|| lines);
 }