os/trap/
context.rs

1//! Implementation of [`TrapContext`]
2use riscv::register::sstatus::{self, SPP, Sstatus};
3
4#[repr(C)]
5///trap context structure containing sstatus, sepc and registers
6pub struct TrapContext {
7    /// general regs[0..31]
8    pub x: [usize; 32],
9    /// CSR sstatus      
10    pub sstatus: Sstatus,
11    /// CSR sepc
12    pub sepc: usize,
13    /// Addr of Page Table
14    pub kernel_satp: usize,
15    /// kernel stack
16    pub kernel_sp: usize,
17    /// Addr of trap_handler function
18    pub trap_handler: usize,
19}
20
21impl TrapContext {
22    ///set stack pointer to x_2 reg (sp)
23    pub fn set_sp(&mut self, sp: usize) {
24        self.x[2] = sp;
25    }
26    ///init app context
27    pub fn app_init_context(
28        entry: usize,
29        sp: usize,
30        kernel_satp: usize,
31        kernel_sp: usize,
32        trap_handler: usize,
33    ) -> Self {
34        let mut sstatus = sstatus::read();
35        // set CPU privilege to User after trapping back
36        sstatus.set_spp(SPP::User);
37        let mut cx = Self {
38            x: [0; 32],
39            sstatus,
40            sepc: entry,
41            kernel_satp,
42            kernel_sp,
43            trap_handler,
44        };
45        cx.set_sp(sp);
46        cx
47    }
48}
os/trap/context.rs

os/trap/
context.rs
