riscv: 初始化irq (#560)

完成riscv的irqchip初始化的代码。

这是该功能的第一个PR。由于还需要实现timer驱动才能测试，因此该功能将会通过2~3个PR来完成。

kernel/src/arch/riscv64/cpu.rs

@@ -1,9 +1,22 @@
-use crate::smp::cpu::ProcessorId;
+use alloc::vec::Vec;
+
+use crate::{
+    init::boot_params,
+    kdebug,
+    mm::percpu::{PerCpu, PerCpuVar},
+    smp::cpu::{ProcessorId, SmpCpuManager},
+};
 
 /// 获取当前cpu的id
 #[inline]
 pub fn current_cpu_id() -> ProcessorId {
-    unimplemented!("RiscV64 current_cpu_id")
+    let ptr: *const LocalContext = riscv::register::sscratch::read() as *const LocalContext;
+
+    if core::intrinsics::unlikely(ptr.is_null()) {
+        return boot_params().read_irqsave().arch.boot_hartid;
+    }
+
+    unsafe { (*ptr).current_cpu() }
 }
 
 /// 重置cpu
@@ -11,3 +24,64 @@ pub unsafe fn cpu_reset() -> ! {
     sbi_rt::system_reset(sbi_rt::WarmReboot, sbi_rt::NoReason);
     unimplemented!("RiscV64 reset failed, manual override expected ...")
 }
+
+static mut LOCAL_CONTEXT: Option<PerCpuVar<LocalContext>> = None;
+
+#[inline(always)]
+pub(super) fn local_context() -> &'static PerCpuVar<LocalContext> {
+    unsafe { LOCAL_CONTEXT.as_ref().unwrap() }
+}
+
+/// Per cpu的上下文数据
+///
+/// 每个CPU的sscratch寄存器指向这个结构体
+#[derive(Debug)]
+pub(super) struct LocalContext {
+    /// 当前cpu的id
+    current_cpu: ProcessorId,
+}
+
+impl LocalContext {
+    fn new(cpu: ProcessorId) -> Self {
+        Self { current_cpu: cpu }
+    }
+    pub fn current_cpu(&self) -> ProcessorId {
+        self.current_cpu
+    }
+
+    pub fn set_current_cpu(&mut self, cpu: ProcessorId) {
+        self.current_cpu = cpu;
+    }
+
+    fn sync_to_cpu(&self) {
+        let ptr = self as *const Self as usize;
+        riscv::register::sscratch::write(ptr);
+    }
+}
+
+/// 初始化本地上下文
+#[inline(never)]
+pub(super) fn init_local_context() {
+    kdebug!("init_local_context");
+    let mut data = Vec::new();
+
+    for i in 0..PerCpu::MAX_CPU_NUM {
+        data.push(LocalContext::new(ProcessorId::new(i)));
+    }
+    let ctx = PerCpuVar::new(data).unwrap();
+
+    unsafe {
+        LOCAL_CONTEXT = Some(ctx);
+    }
+
+    let hartid = boot_params().read().arch.boot_hartid;
+
+    let ctx = unsafe { local_context().force_get(hartid) };
+    ctx.sync_to_cpu();
+}
+
+impl SmpCpuManager {
+    pub fn arch_init(boot_cpu: ProcessorId) {
+        // todo: 读取所有可用的CPU
+    }
+}