add os[1-8]-ref for os refereces, add guide, add README

os5-ref/src/syscall/fs.rs

@@ -0,0 +1,50 @@
+//! File and filesystem-related syscalls
+
+use crate::mm::translated_byte_buffer;
+use crate::sbi::console_getchar;
+use crate::task::{current_user_token, suspend_current_and_run_next};
+
+const FD_STDIN: usize = 0;
+const FD_STDOUT: usize = 1;
+
+pub fn sys_write(fd: usize, buf: *const u8, len: usize) -> isize {
+    match fd {
+        FD_STDOUT => {
+            let buffers = translated_byte_buffer(current_user_token(), buf, len);
+            for buffer in buffers {
+                print!("{}", core::str::from_utf8(buffer).unwrap());
+            }
+            len as isize
+        }
+        _ => {
+            panic!("Unsupported fd in sys_write!");
+        }
+    }
+}
+
+pub fn sys_read(fd: usize, buf: *const u8, len: usize) -> isize {
+    match fd {
+        FD_STDIN => {
+            assert_eq!(len, 1, "Only support len = 1 in sys_read!");
+            let mut c: usize;
+            loop {
+                c = console_getchar();
+                if c == 0 {
+                    suspend_current_and_run_next();
+                    continue;
+                } else {
+                    break;
+                }
+            }
+            let ch = c as u8;
+            let mut buffers = translated_byte_buffer(current_user_token(), buf, len);
+            unsafe {
+                buffers[0].as_mut_ptr().write_volatile(ch);
+            }
+            1
+        }
+        _ => {
+            panic!("Unsupported fd in sys_read!");
+        }
+    }
+}

os5-ref/src/syscall/mod.rs

@@ -0,0 +1,53 @@
+//! Implementation of syscalls
+//!
+//! The single entry point to all system calls, [`syscall()`], is called
+//! whenever userspace wishes to perform a system call using the `ecall`
+//! instruction. In this case, the processor raises an 'Environment call from
+//! U-mode' exception, which is handled as one of the cases in
+//! [`crate::trap::trap_handler`].
+//!
+//! For clarity, each single syscall is implemented as its own function, named
+//! `sys_` then the name of the syscall. You can find functions like this in
+//! submodules, and you should also implement syscalls this way.
+
+const SYSCALL_READ: usize = 63;
+const SYSCALL_WRITE: usize = 64;
+const SYSCALL_EXIT: usize = 93;
+const SYSCALL_YIELD: usize = 124;
+const SYSCALL_GET_TIME: usize = 169;
+const SYSCALL_GETPID: usize = 172;
+const SYSCALL_FORK: usize = 220;
+const SYSCALL_EXEC: usize = 221;
+const SYSCALL_WAITPID: usize = 260;
+const SYSCALL_SPAWN: usize = 400;
+const SYSCALL_MUNMAP: usize = 215;
+const SYSCALL_MMAP: usize = 222;
+const SYSCALL_SET_PRIORITY: usize = 140;
+const SYSCALL_TASK_INFO: usize = 410;
+
+mod fs;
+mod process;
+
+use fs::*;
+use process::*;
+
+/// handle syscall exception with `syscall_id` and other arguments
+pub fn syscall(syscall_id: usize, args: [usize; 3]) -> isize {
+    match syscall_id {
+        SYSCALL_READ => sys_read(args[0], args[1] as *const u8, args[2]),
+        SYSCALL_WRITE => sys_write(args[0], args[1] as *const u8, args[2]),
+        SYSCALL_EXIT => sys_exit(args[0] as i32),
+        SYSCALL_YIELD => sys_yield(),
+        SYSCALL_GETPID => sys_getpid(),
+        SYSCALL_FORK => sys_fork(),
+        SYSCALL_EXEC => sys_exec(args[0] as *const u8),
+        SYSCALL_WAITPID => sys_waitpid(args[0] as isize, args[1] as *mut i32),
+        SYSCALL_GET_TIME => sys_get_time(args[0] as *mut TimeVal, args[1]),
+        SYSCALL_MMAP => sys_mmap(args[0], args[1], args[2]),
+        SYSCALL_MUNMAP => sys_munmap(args[0], args[1]),
+        SYSCALL_SET_PRIORITY => sys_set_priority(args[0] as isize),
+        SYSCALL_TASK_INFO => sys_task_info(args[0] as *mut TaskInfo),
+        SYSCALL_SPAWN => sys_spawn(args[0] as *const u8),
+        _ => panic!("Unsupported syscall_id: {}", syscall_id),
+    }
+}

os5-ref/src/syscall/process.rs

@@ -0,0 +1,144 @@
+//! Process management syscalls
+
+use crate::loader::get_app_data_by_name;
+use crate::mm::{translated_refmut, translated_str};
+use crate::task::{
+    add_task, current_task, current_user_token, exit_current_and_run_next,
+    suspend_current_and_run_next, TaskStatus,
+};
+use crate::timer::get_time_us;
+use alloc::sync::Arc;
+use crate::config::MAX_SYSCALL_NUM;
+
+#[repr(C)]
+#[derive(Debug)]
+pub struct TimeVal {
+    pub sec: usize,
+    pub usec: usize,
+}
+
+#[derive(Clone, Copy)]
+pub struct TaskInfo {
+    pub status: TaskStatus,
+    pub syscall_times: [u32; MAX_SYSCALL_NUM],
+    pub time: usize,
+}
+
+pub fn sys_exit(exit_code: i32) -> ! {
+    debug!("[kernel] Application exited with code {}", exit_code);
+    exit_current_and_run_next(exit_code);
+    panic!("Unreachable in sys_exit!");
+}
+
+/// current task gives up resources for other tasks
+pub fn sys_yield() -> isize {
+    suspend_current_and_run_next();
+    0
+}
+
+pub fn sys_getpid() -> isize {
+    current_task().unwrap().pid.0 as isize
+}
+
+/// Syscall Fork which returns 0 for child process and child_pid for parent process
+pub fn sys_fork() -> isize {
+    let current_task = current_task().unwrap();
+    let new_task = current_task.fork();
+    let new_pid = new_task.pid.0;
+    // modify trap context of new_task, because it returns immediately after switching
+    let trap_cx = new_task.inner_exclusive_access().get_trap_cx();
+    // we do not have to move to next instruction since we have done it before
+    // for child process, fork returns 0
+    trap_cx.x[10] = 0;
+    // add new task to scheduler
+    add_task(new_task);
+    new_pid as isize
+}
+
+/// Syscall Exec which accepts the elf path
+pub fn sys_exec(path: *const u8) -> isize {
+    let token = current_user_token();
+    let path = translated_str(token, path);
+    if let Some(data) = get_app_data_by_name(path.as_str()) {
+        let task = current_task().unwrap();
+        task.exec(data);
+        0
+    } else {
+        -1
+    }
+}
+
+/// If there is not a child process whose pid is same as given, return -1.
+/// Else if there is a child process but it is still running, return -2.
+pub fn sys_waitpid(pid: isize, exit_code_ptr: *mut i32) -> isize {
+    let task = current_task().unwrap();
+    // find a child process
+
+    // ---- access current TCB exclusively
+    let mut inner = task.inner_exclusive_access();
+    if !inner
+        .children
+        .iter()
+        .any(|p| pid == -1 || pid as usize == p.getpid())
+    {
+        return -1;
+        // ---- release current PCB
+    }
+    let pair = inner.children.iter().enumerate().find(|(_, p)| {
+        // ++++ temporarily access child PCB lock exclusively
+        p.inner_exclusive_access().is_zombie() && (pid == -1 || pid as usize == p.getpid())
+        // ++++ release child PCB
+    });
+    if let Some((idx, _)) = pair {
+        let child = inner.children.remove(idx);
+        // confirm that child will be deallocated after removing from children list
+        assert_eq!(Arc::strong_count(&child), 1);
+        let found_pid = child.getpid();
+        // ++++ temporarily access child TCB exclusively
+        let exit_code = child.inner_exclusive_access().exit_code;
+        // ++++ release child PCB
+        *translated_refmut(inner.memory_set.token(), exit_code_ptr) = exit_code;
+        found_pid as isize
+    } else {
+        -2
+    }
+    // ---- release current PCB lock automatically
+}
+
+// YOUR JOB: 引入虚地址后重写 sys_get_time
+pub fn sys_get_time(_ts: *mut TimeVal, _tz: usize) -> isize {
+    let _us = get_time_us();
+    // unsafe {
+    //     *ts = TimeVal {
+    //         sec: us / 1_000_000,
+    //         usec: us % 1_000_000,
+    //     };
+    // }
+    0
+}
+
+// YOUR JOB: 引入虚地址后重写 sys_task_info
+pub fn sys_task_info(ti: *mut TaskInfo) -> isize {
+    -1
+}
+
+// YOUR JOB: 实现sys_set_priority，为任务添加优先级
+pub fn sys_set_priority(_prio: isize) -> isize {
+    -1
+}
+
+// YOUR JOB: 扩展内核以实现 sys_mmap 和 sys_munmap
+pub fn sys_mmap(_start: usize, _len: usize, _port: usize) -> isize {
+    -1
+}
+
+pub fn sys_munmap(_start: usize, _len: usize) -> isize {
+    -1
+}
+
+//
+// YOUR JOB: 实现 sys_spawn 系统调用
+// ALERT: 注意在实现 SPAWN 时不需要复制父进程地址空间，SPAWN != FORK + EXEC 
+pub fn sys_spawn(_path: *const u8) -> isize {
+    -1
+}