79 lines
2.5 KiB
Rust
79 lines
2.5 KiB
Rust
//! Trap handling functionality
|
|
//!
|
|
//! For rCore, we have a single trap entry point, namely `__alltraps`. At
|
|
//! initialization in [`init()`], we set the `stvec` CSR to point to it.
|
|
//!
|
|
//! All traps go through `__alltraps`, which is defined in `trap.S`. The
|
|
//! assembly language code does just enough work restore the kernel space
|
|
//! context, ensuring that Rust code safely runs, and transfers control to
|
|
//! [`trap_handler()`].
|
|
//!
|
|
//! It then calls different functionality based on what exactly the exception
|
|
//! was. For example, timer interrupts trigger task preemption, and syscalls go
|
|
//! to [`syscall()`].
|
|
|
|
mod context;
|
|
|
|
use crate::syscall::syscall;
|
|
use crate::task::{exit_current_and_run_next, suspend_current_and_run_next};
|
|
use crate::timer::set_next_trigger;
|
|
use core::arch::global_asm;
|
|
use riscv::register::{
|
|
mtvec::TrapMode,
|
|
scause::{self, Exception, Interrupt, Trap},
|
|
sie, stval, stvec,
|
|
};
|
|
|
|
global_asm!(include_str!("trap.S"));
|
|
|
|
/// initialize CSR `stvec` as the entry of `__alltraps`
|
|
pub fn init() {
|
|
extern "C" {
|
|
fn __alltraps();
|
|
}
|
|
unsafe {
|
|
stvec::write(__alltraps as usize, TrapMode::Direct);
|
|
}
|
|
}
|
|
|
|
/// timer interrupt enabled
|
|
pub fn enable_timer_interrupt() {
|
|
unsafe {
|
|
sie::set_stimer();
|
|
}
|
|
}
|
|
|
|
#[no_mangle]
|
|
/// handle an interrupt, exception, or system call from user space
|
|
pub fn trap_handler(cx: &mut TrapContext) -> &mut TrapContext {
|
|
let scause = scause::read(); // get trap cause
|
|
let stval = stval::read(); // get extra value
|
|
match scause.cause() {
|
|
Trap::Exception(Exception::UserEnvCall) => {
|
|
cx.sepc += 4;
|
|
cx.x[10] = syscall(cx.x[17], [cx.x[10], cx.x[11], cx.x[12]]) as usize;
|
|
}
|
|
Trap::Exception(Exception::StoreFault) | Trap::Exception(Exception::StorePageFault) => {
|
|
println!("[kernel] PageFault in application, bad addr = {:#x}, bad instruction = {:#x}, kernel killed it.", stval, cx.sepc);
|
|
exit_current_and_run_next();
|
|
}
|
|
Trap::Exception(Exception::IllegalInstruction) => {
|
|
println!("[kernel] IllegalInstruction in application, kernel killed it.");
|
|
exit_current_and_run_next();
|
|
}
|
|
Trap::Interrupt(Interrupt::SupervisorTimer) => {
|
|
set_next_trigger();
|
|
suspend_current_and_run_next();
|
|
}
|
|
_ => {
|
|
panic!(
|
|
"Unsupported trap {:?}, stval = {:#x}!",
|
|
scause.cause(),
|
|
stval
|
|
);
|
|
}
|
|
}
|
|
cx
|
|
}
|
|
|
|
pub use context::TrapContext;
|