129 lines
3.6 KiB
Rust
129 lines
3.6 KiB
Rust
mod context;
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use crate::config::TRAMPOLINE;
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use crate::syscall::syscall;
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use crate::task::{
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check_signals_of_current, current_add_signal, current_trap_cx, current_trap_cx_user_va,
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current_user_token, exit_current_and_run_next, suspend_current_and_run_next, SignalFlags,
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};
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use crate::timer::{check_timer, set_next_trigger};
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use core::arch::{asm, global_asm};
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use riscv::register::{
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mtvec::TrapMode,
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scause::{self, Exception, Interrupt, Trap},
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sie, stval, stvec,
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};
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global_asm!(include_str!("trap.S"));
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pub fn init() {
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set_kernel_trap_entry();
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}
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fn set_kernel_trap_entry() {
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unsafe {
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stvec::write(trap_from_kernel as usize, TrapMode::Direct);
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}
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}
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fn set_user_trap_entry() {
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unsafe {
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stvec::write(TRAMPOLINE as usize, TrapMode::Direct);
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}
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}
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pub fn enable_timer_interrupt() {
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unsafe {
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sie::set_stimer();
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}
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}
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#[no_mangle]
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pub fn trap_handler() -> ! {
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set_kernel_trap_entry();
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let scause = scause::read();
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let stval = stval::read();
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match scause.cause() {
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Trap::Exception(Exception::UserEnvCall) => {
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// jump to next instruction anyway
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let mut cx = current_trap_cx();
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cx.sepc += 4;
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// get system call return value
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let result = syscall(cx.x[17], [cx.x[10], cx.x[11], cx.x[12]]);
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// cx is changed during sys_exec, so we have to call it again
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cx = current_trap_cx();
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cx.x[10] = result as usize;
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}
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Trap::Exception(Exception::StoreFault)
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| Trap::Exception(Exception::StorePageFault)
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| Trap::Exception(Exception::InstructionFault)
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| Trap::Exception(Exception::InstructionPageFault)
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| Trap::Exception(Exception::LoadFault)
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| Trap::Exception(Exception::LoadPageFault) => {
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/*
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println!(
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"[kernel] {:?} in application, bad addr = {:#x}, bad instruction = {:#x}, kernel killed it.",
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scause.cause(),
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stval,
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current_trap_cx().sepc,
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);
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*/
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current_add_signal(SignalFlags::SIGSEGV);
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}
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Trap::Exception(Exception::IllegalInstruction) => {
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current_add_signal(SignalFlags::SIGILL);
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}
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Trap::Interrupt(Interrupt::SupervisorTimer) => {
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set_next_trigger();
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check_timer();
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suspend_current_and_run_next();
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}
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Trap::Interrupt(Interrupt::SupervisorExternal) => {
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crate::board::irq_handler();
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}
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_ => {
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panic!(
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"Unsupported trap {:?}, stval = {:#x}!",
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scause.cause(),
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stval
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);
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}
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}
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// check signals
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if let Some((errno, msg)) = check_signals_of_current() {
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println!("[kernel] {}", msg);
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exit_current_and_run_next(errno);
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}
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trap_return();
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}
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#[no_mangle]
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pub fn trap_return() -> ! {
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set_user_trap_entry();
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let trap_cx_user_va = current_trap_cx_user_va();
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let user_satp = current_user_token();
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extern "C" {
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fn __alltraps();
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fn __restore();
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}
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let restore_va = __restore as usize - __alltraps as usize + TRAMPOLINE;
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unsafe {
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asm!(
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"fence.i",
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"jr {restore_va}",
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restore_va = in(reg) restore_va,
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in("a0") trap_cx_user_va,
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in("a1") user_satp,
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options(noreturn)
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);
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}
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}
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#[no_mangle]
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pub fn trap_from_kernel() -> ! {
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use riscv::register::sepc;
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println!("stval = {:#x}, sepc = {:#x}", stval::read(), sepc::read());
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panic!("a trap {:?} from kernel!", scause::read().cause());
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}
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pub use context::TrapContext;
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