keos/
task.rs

1//! Task trait for interact with user process.
2
3use crate::thread::kill_current_thread;
4pub use abyss::x86_64::interrupt::PFErrorCode;
5use abyss::{
6    addressing::{Pa, Va},
7    interrupt::Registers,
8};
9use core::ops::Range;
10
11/// Represents a **task** executed by a thread.
12///
13/// This trait defines core functionalities required for handling event
14/// triggered by user process, such as **system calls**, **page faults**.
15pub trait Task {
16    /// Handles a **system call** triggered by the user program.
17    ///
18    /// - The `registers` parameter contains the state of the CPU registers at
19    ///   the time of the system call.
20    /// - Implementations of this function should parse the system call
21    ///   arguments, execute the corresponding operation, and store the result
22    ///   back in `registers`.
23    fn syscall(&mut self, registers: &mut Registers);
24
25    /// Handles a **page fault** that occurs when accessing an unmapped memory
26    /// page.
27    ///
28    /// - The `ec` parameter provides information about the cause of the page
29    ///   fault.
30    fn page_fault(&mut self, ec: PFErrorCode, cr2: Va) {
31        if (ec & PFErrorCode::USER) == PFErrorCode::USER {
32            println!(
33                "[ERROR] Page fault occurs by {:?} [0x{:x}]. Killing thread...",
34                if !ec.contains(PFErrorCode::PRESENT) {
35                    "accessing non-present page"
36                } else if ec.contains(PFErrorCode::INSTRCUTION_FETCH) {
37                    "executing non-executable page"
38                } else if ec.contains(PFErrorCode::WRITE_ACCESS) {
39                    "writing to a read-only page"
40                } else {
41                    "other protection violation on page"
42                },
43                cr2.into_usize(),
44            );
45            kill_current_thread();
46        } else {
47            panic!(
48                "Unexpected page fault in Kernel at {:?} because of {:?}",
49                cr2, ec
50            );
51        }
52    }
53
54    /// Validates a given **memory address range** before use.
55    ///
56    /// - `addr`: The range of virtual addresses being accessed.
57    /// - `is_write`: Indicates whether the memory is being **read** (`false`)
58    ///   or **written to** (`true`).
59    /// - Returns `true` if the memory range is valid, or an appropriate
60    ///   `KernelError` otherwise.
61    #[allow(unused_variables)]
62    fn access_ok(&self, addr: Range<Va>, is_write: bool) -> bool {
63        // Currently, check only addr is null pointer.
64        addr.start.into_usize() != 0
65    }
66
67    /// Run a closure with physical address of the page table.
68    fn with_page_table_pa(&self, _f: &fn(Pa)) {}
69}
70
71impl Task for () {
72    fn syscall(&mut self, _registers: &mut Registers) {
73        unreachable!()
74    }
75}
keos/task.rs

keos/
task.rs
