xref: /DragonOS/kernel/src/arch/riscv64/cpu.rs (revision 471d65cf158c9bf741c21f5d0ab92efe7bf1c3d4)
1 use alloc::vec::Vec;
2 use sbi_rt::HartMask;
3 
4 use crate::{
5     init::boot_params,
6     mm::percpu::{PerCpu, PerCpuVar},
7     smp::cpu::{ProcessorId, SmpCpuManager},
8 };
9 
10 /// 栈对齐
11 pub(super) const STACK_ALIGN: usize = 16;
12 
13 /// RISC-V的XLEN,也就是寄存器的位宽
14 pub const RISCV_XLEN: usize = core::mem::size_of::<usize>() * 8;
15 
16 /// 获取当前cpu的id
17 #[inline]
18 pub fn current_cpu_id() -> ProcessorId {
19     let ptr: *const LocalContext = riscv::register::tp::read() as *const LocalContext;
20 
21     if core::intrinsics::unlikely(ptr.is_null()) {
22         return boot_params().read_irqsave().arch.boot_hartid;
23     }
24 
25     unsafe { (*ptr).current_cpu() }
26 }
27 impl Into<HartMask> for ProcessorId {
28     fn into(self) -> HartMask {
29         let base = self.data() as usize / RISCV_XLEN;
30         let offset = self.data() as usize & (RISCV_XLEN - 1);
31         HartMask::from_mask_base(offset, base)
32     }
33 }
34 /// 重置cpu
35 pub unsafe fn cpu_reset() -> ! {
36     sbi_rt::system_reset(sbi_rt::WarmReboot, sbi_rt::NoReason);
37     unimplemented!("RiscV64 reset failed, manual override expected ...")
38 }
39 
40 static mut LOCAL_CONTEXT: Option<PerCpuVar<LocalContext>> = None;
41 
42 #[inline(always)]
43 pub(super) fn local_context() -> &'static PerCpuVar<LocalContext> {
44     unsafe { LOCAL_CONTEXT.as_ref().unwrap() }
45 }
46 
47 /// Per cpu的上下文数据
48 ///
49 /// 每个CPU的tp寄存器指向这个结构体
50 ///
51 /// 注意:
52 ///
53 /// - 从用户态进入内核态时,会从sscratch寄存器加载这个结构体的地址到tp寄存器,并把sscratch寄存器清零
54 /// - 从内核态进入用户态时,会将tp寄存器的值保存到sscratch寄存器
55 #[derive(Debug, Clone, Copy)]
56 pub(super) struct LocalContext {
57     /// 当前cpu的id
58     pub current_cpu: ProcessorId,
59     // 当前进程的内核栈指针(暂存,当进入中断处理程序的时候需要保存到pcb,进程切换的时候需要重新设置这个值)
60     pub kernel_sp: usize,
61     // 当前进程的用户栈指针(暂存,当进入中断处理程序的时候需要保存到pcb,进程切换的时候需要重新设置这个值)
62     pub user_sp: usize,
63 }
64 
65 impl LocalContext {
66     pub fn new(cpu: ProcessorId) -> Self {
67         Self {
68             current_cpu: cpu,
69             kernel_sp: 0,
70             user_sp: 0,
71         }
72     }
73     pub fn current_cpu(&self) -> ProcessorId {
74         self.current_cpu
75     }
76 
77     pub fn set_current_cpu(&mut self, cpu: ProcessorId) {
78         self.current_cpu = cpu;
79     }
80 
81     pub fn kernel_sp(&self) -> usize {
82         self.kernel_sp
83     }
84 
85     pub fn set_kernel_sp(&mut self, sp: usize) {
86         self.kernel_sp = sp;
87     }
88 
89     pub fn user_sp(&self) -> usize {
90         self.user_sp
91     }
92 
93     pub fn set_user_sp(&mut self, sp: usize) {
94         self.user_sp = sp;
95     }
96 
97     fn sync_to_cpu(&self) {
98         let ptr = self as *const Self as usize;
99         riscv::register::sscratch::write(0);
100 
101         // 写入tp寄存器
102         riscv::register::tp::write(ptr);
103     }
104 
105     pub fn restore(&mut self, from: &LocalContext) {
106         // 不恢复cpu id
107 
108         self.kernel_sp = from.kernel_sp;
109         self.user_sp = from.user_sp;
110     }
111 }
112 
113 /// 初始化本地上下文
114 #[inline(never)]
115 pub(super) fn init_local_context() {
116     let mut data = Vec::new();
117 
118     for i in 0..PerCpu::MAX_CPU_NUM {
119         data.push(LocalContext::new(ProcessorId::new(i)));
120     }
121     let ctx = PerCpuVar::new(data).unwrap();
122 
123     unsafe {
124         LOCAL_CONTEXT = Some(ctx);
125     }
126 
127     let hartid = boot_params().read().arch.boot_hartid;
128 
129     let ctx = unsafe { local_context().force_get(hartid) };
130     ctx.sync_to_cpu();
131 }
132 
133 impl SmpCpuManager {
134     pub fn arch_init(boot_cpu: ProcessorId) {
135         // todo: 读取所有可用的CPU
136     }
137 }
138