Switch ok with debug mode apps, implement sys_exit correctly later.

os/build.rs

@@ -6,7 +6,7 @@ fn main() {
     insert_app_data().unwrap();
 }
 
-static TARGET_PATH: &str = "../user/target/riscv64gc-unknown-none-elf/release/";
+static TARGET_PATH: &str = "../user/target/riscv64gc-unknown-none-elf/debug/";
 
 fn insert_app_data() -> Result<()> {
     let mut f = File::create("src/link_app.S").unwrap();

os/src/batch.rs

@@ -1,129 +0,0 @@
-use core::cell::RefCell;
-use lazy_static::*;
-use crate::trap::TrapContext;
-
-const USER_STACK_SIZE: usize = 4096 * 2;
-const KERNEL_STACK_SIZE: usize = 4096 * 2;
-const MAX_APP_NUM: usize = 16;
-const APP_BASE_ADDRESS: usize = 0x80040000;
-const APP_SIZE_LIMIT: usize = 0x20000;
-
-#[repr(align(4096))]
-struct KernelStack {
-    data: [u8; KERNEL_STACK_SIZE],
-}
-
-#[repr(align(4096))]
-struct UserStack {
-    data: [u8; USER_STACK_SIZE],
-}
-
-static KERNEL_STACK: KernelStack = KernelStack { data: [0; KERNEL_STACK_SIZE] };
-static USER_STACK: UserStack = UserStack { data: [0; USER_STACK_SIZE] };
-
-impl KernelStack {
-    fn get_sp(&self) -> usize {
-        self.data.as_ptr() as usize + KERNEL_STACK_SIZE
-    }
-    pub fn push_context(&self, cx: TrapContext) -> &'static mut TrapContext {
-        let cx_ptr = (self.get_sp() - core::mem::size_of::<TrapContext>()) as *mut TrapContext;
-        unsafe { *cx_ptr = cx; }
-        unsafe { cx_ptr.as_mut().unwrap() }
-    }
-}
-
-impl UserStack {
-    fn get_sp(&self) -> usize {
-        self.data.as_ptr() as usize + USER_STACK_SIZE
-    }
-}
-
-struct AppManager {
-    inner: RefCell<AppManagerInner>,
-}
-struct AppManagerInner {
-    num_app: usize,
-    current_app: usize,
-    app_start: [usize; MAX_APP_NUM + 1],
-}
-unsafe impl Sync for AppManager {}
-
-impl AppManagerInner {
-    pub fn print_app_info(&self) {
-        println!("[kernel] num_app = {}", self.num_app);
-        for i in 0..self.num_app {
-            println!("[kernel] app_{} [{:#x}, {:#x})", i, self.app_start[i], self.app_start[i + 1]);
-        }
-    }
-
-    unsafe fn load_app(&self, app_id: usize) {
-        if app_id >= self.num_app {
-            panic!("All applications completed!");
-        }
-        println!("[kernel] Loading app_{}", app_id);
-        // clear icache
-        llvm_asm!("fence.i" :::: "volatile");
-        // clear app area
-        (APP_BASE_ADDRESS..APP_BASE_ADDRESS + APP_SIZE_LIMIT).for_each(|addr| {
-            (addr as *mut u8).write_volatile(0);
-        });
-        let app_src = core::slice::from_raw_parts(
-            self.app_start[app_id] as *const u8,
-            self.app_start[app_id + 1] - self.app_start[app_id]
-        );
-        let app_dst = core::slice::from_raw_parts_mut(
-            APP_BASE_ADDRESS as *mut u8,
-            app_src.len()
-        );
-        app_dst.copy_from_slice(app_src);
-    }
-
-    pub fn get_current_app(&self) -> usize { self.current_app }
-
-    pub fn move_to_next_app(&mut self) {
-        self.current_app += 1;
-    }
-}
-
-lazy_static! {
-    static ref APP_MANAGER: AppManager = AppManager {
-        inner: RefCell::new({
-            extern "C" { fn _num_app(); }
-            let num_app_ptr = _num_app as usize as *const usize;
-            let num_app = unsafe { num_app_ptr.read_volatile() };
-            let mut app_start: [usize; MAX_APP_NUM + 1] = [0; MAX_APP_NUM + 1];
-            let app_start_raw: &[usize] = unsafe {
-                core::slice::from_raw_parts(num_app_ptr.add(1), num_app + 1)
-            };
-            app_start[..=num_app].copy_from_slice(app_start_raw);
-            AppManagerInner {
-                num_app,
-                current_app: 0,
-                app_start,
-            }
-        }),
-    };
-}
-
-pub fn init() {
-    print_app_info();
-}
-
-pub fn print_app_info() {
-    APP_MANAGER.inner.borrow().print_app_info();
-}
-
-pub fn run_next_app() -> ! {
-    let current_app = APP_MANAGER.inner.borrow().get_current_app();
-    unsafe {
-        APP_MANAGER.inner.borrow().load_app(current_app);
-    }
-    APP_MANAGER.inner.borrow_mut().move_to_next_app();
-    extern "C" { fn __restore(cx_addr: usize); }
-    unsafe {
-        __restore(KERNEL_STACK.push_context(
-            TrapContext::app_init_context(APP_BASE_ADDRESS, USER_STACK.get_sp())
-        ) as *const _ as usize);
-    }
-    panic!("Unreachable in batch::run_current_app!");
-}

os/src/config.rs

@@ -0,0 +1,5 @@
+pub const USER_STACK_SIZE: usize = 4096 * 2;
+pub const KERNEL_STACK_SIZE: usize = 4096 * 2;
+pub const MAX_APP_NUM: usize = 4;
+pub const APP_BASE_ADDRESS: usize = 0x80100000;
+pub const APP_SIZE_LIMIT: usize = 0x20000;

os/src/loader.rs

@@ -0,0 +1,94 @@
+use core::cell::RefCell;
+use lazy_static::*;
+use crate::trap::TrapContext;
+use crate::task::TaskContext;
+use crate::config::*;
+
+#[repr(align(4096))]
+struct KernelStack {
+    data: [u8; KERNEL_STACK_SIZE],
+}
+
+#[repr(align(4096))]
+struct UserStack {
+    data: [u8; USER_STACK_SIZE],
+}
+
+static KERNEL_STACK: [KernelStack; MAX_APP_NUM] = [
+    KernelStack { data: [0; KERNEL_STACK_SIZE], };
+    MAX_APP_NUM
+];
+
+static USER_STACK: [UserStack; MAX_APP_NUM] = [
+    UserStack { data: [0; USER_STACK_SIZE], };
+    MAX_APP_NUM
+];
+
+impl KernelStack {
+    fn get_sp(&self) -> usize {
+        self.data.as_ptr() as usize + KERNEL_STACK_SIZE
+    }
+    pub fn push_context(&self, trap_cx: TrapContext, task_cx: TaskContext) -> &'static mut TaskContext {
+        let trap_cx_ptr = (self.get_sp() - core::mem::size_of::<TrapContext>()) as *mut TrapContext;
+        unsafe { *trap_cx_ptr = trap_cx; }
+        let task_cx_ptr = (trap_cx_ptr as usize - core::mem::size_of::<TaskContext>()) as *mut TaskContext;
+        unsafe { *task_cx_ptr = task_cx; }
+        unsafe { task_cx_ptr.as_mut().unwrap() }
+    }
+}
+
+impl UserStack {
+    fn get_sp(&self) -> usize {
+        self.data.as_ptr() as usize + USER_STACK_SIZE
+    }
+}
+
+fn get_base_i(app_id: usize) -> usize {
+    APP_BASE_ADDRESS + app_id * APP_SIZE_LIMIT
+}
+
+pub fn get_num_app() -> usize {
+    extern "C" { fn _num_app(); }
+    unsafe { (_num_app as usize as *const usize).read_volatile() }
+}
+
+pub fn load_apps() {
+    extern "C" { fn _num_app(); }
+    let num_app_ptr = _num_app as usize as *const usize;
+    let num_app = get_num_app();
+    let app_start = unsafe {
+        core::slice::from_raw_parts(num_app_ptr.add(1), num_app + 1)
+    };
+    // clear i-cache first
+    unsafe { llvm_asm!("fence.i" :::: "volatile"); }
+    // load apps
+    for i in 0..num_app {
+        println!("i = {}", i);
+        println!("[{:#x}, {:#x})", app_start[i], app_start[i + 1]);
+        let base_i = get_base_i(i);
+        // clear region
+        (base_i..base_i + APP_SIZE_LIMIT).for_each(|addr| unsafe {
+            (addr as *mut u8).write_volatile(0)
+        });
+        // load app from data section to memory
+        let src = unsafe {
+            core::slice::from_raw_parts(app_start[i] as *const u8, app_start[i + 1] - app_start[i])
+        };
+        let dst = unsafe {
+            core::slice::from_raw_parts_mut(base_i as *mut u8, src.len())
+        };
+        dst.copy_from_slice(src);
+    }
+}
+
+pub fn init_app_cx(app_id: usize) -> &'static TaskContext {
+    println!("app_id = {}, kernel_sp = {:#x}, user_sp = {:#x}",
+             app_id,
+             KERNEL_STACK[app_id].get_sp(),
+             USER_STACK[app_id].get_sp()
+    );
+    KERNEL_STACK[app_id].push_context(
+        TrapContext::app_init_context(get_base_i(app_id), USER_STACK[app_id].get_sp()),
+        TaskContext::goto_restore(),
+    )
+}

os/src/main.rs

@@ -3,6 +3,7 @@
 #![feature(global_asm)]
 #![feature(llvm_asm)]
 #![feature(panic_info_message)]
+#![feature(const_in_array_repeat_expressions)]
 
 #[macro_use]
 mod console;
@@ -10,7 +11,9 @@ mod lang_items;
 mod sbi;
 mod syscall;
 mod trap;
-mod batch;
+mod loader;
+mod config;
+mod task;
 
 global_asm!(include_str!("entry.asm"));
 global_asm!(include_str!("link_app.S"));
@@ -30,6 +33,7 @@ pub fn rust_main() -> ! {
     clear_bss();
     println!("[kernel] Hello, world!");
     trap::init();
-    batch::init();
-    batch::run_next_app();
+    loader::load_apps();
+    task::run_first_task();
+    panic!("Unreachable in rust_main!");
 }

os/src/syscall/mod.rs

@@ -1,7 +1,7 @@
 const SYSCALL_WRITE: usize = 64;
 const SYSCALL_EXIT: usize = 93;
 const SYSCALL_YIELD: usize = 124;
-const SYSCALL_GET_TIME: usize = 169;
+//const SYSCALL_GET_TIME: usize = 169;
 
 mod fs;
 mod process;
@@ -13,6 +13,7 @@ pub fn syscall(syscall_id: usize, args: [usize; 3]) -> isize {
     match syscall_id {
         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(),
         _ => panic!("Unsupported syscall_id: {}", syscall_id),
     }
 }

os/src/syscall/process.rs

@@ -1,6 +1,12 @@
-use crate::batch::run_next_app;
+use crate::task::switch_to_next_task;
 
 pub fn sys_exit(xstate: i32) -> ! {
     println!("[kernel] Application exited with code {}", xstate);
-    run_next_app()
+    //run_next_app()
+    panic!("[kernel] first exit!");
+}
+
+pub fn sys_yield() -> isize {
+    switch_to_next_task();
+    0
 }

os/src/task/context.rs

@@ -0,0 +1,16 @@
+#[repr(C)]
+pub struct TaskContext {
+    ra: usize,
+    s: [usize; 12],
+}
+
+impl TaskContext {
+    pub fn goto_restore() -> Self {
+        extern "C" { fn __restore(); }
+        Self {
+            ra: __restore as usize,
+            s: [0; 12],
+        }
+    }
+}
+

os/src/task/mod.rs

@@ -0,0 +1,61 @@
+mod context;
+mod switch;
+
+use crate::config::MAX_APP_NUM;
+use crate::loader::{get_num_app, init_app_cx};
+use core::cell::RefCell;
+use lazy_static::*;
+use switch::__switch;
+
+pub use context::TaskContext;
+
+struct TaskControlBlock {
+    task_cx_ptr: usize,
+}
+
+pub struct TaskManager {
+    num_app: usize,
+    tasks: [TaskControlBlock; MAX_APP_NUM],
+    current_task: RefCell<usize>,
+}
+
+unsafe impl Sync for TaskManager {}
+
+lazy_static! {
+    pub static ref TASK_MANAGER: TaskManager = {
+        let num_app = get_num_app();
+        let mut tasks = [TaskControlBlock { task_cx_ptr: 0 }; MAX_APP_NUM];
+        for i in 0..num_app {
+            tasks[i] = TaskControlBlock { task_cx_ptr: init_app_cx(i) as *const _ as usize, };
+        }
+        TaskManager {
+            num_app,
+            tasks,
+            current_task: RefCell::new(0),
+        }
+    };
+}
+
+impl TaskManager {
+    pub fn run_first_task(&self) {
+        unsafe {
+            __switch(&0usize, &self.tasks[0].task_cx_ptr);
+        }
+    }
+    pub fn switch_to_next_task(&self) {
+        let current = *self.current_task.borrow();
+        let next = if current == self.num_app - 1 { 0 } else { current + 1 };
+        *self.current_task.borrow_mut() = next;
+        unsafe {
+            __switch(&self.tasks[current].task_cx_ptr, &self.tasks[next].task_cx_ptr);
+        }
+    }
+}
+
+pub fn run_first_task() {
+    TASK_MANAGER.run_first_task();
+}
+
+pub fn switch_to_next_task() {
+    TASK_MANAGER.switch_to_next_task();
+}

os/src/task/switch.S

@@ -0,0 +1,34 @@
+.altmacro
+.macro SAVE_SN n
+    sd s\n, (\n+1)*8(sp)
+.endm
+.macro LOAD_SN n
+    ld s\n, (\n+1)*8(sp)
+.endm
+    .section .text
+    .globl __switch
+__switch:
+    # __switch(current_task_cx: &*const TaskContext, next_task_cx: &*const TaskContext)
+    # push TaskContext to current sp and save its address to where a0 points to
+    addi sp, sp, -13*8
+    sd sp, 0(a0)
+    # fill TaskContext with ra & s0-s11
+    sd ra, 0(sp)
+    .set n, 0
+    .rept 12
+        SAVE_SN %n
+        .set n, n + 1
+    .endr
+    # ready for loading TaskContext a1 points to
+    ld sp, 0(a1)
+    # load registers in the TaskContext
+    ld ra, 0(sp)
+    .set n, 0
+    .rept 12
+        LOAD_SN %n
+        .set n, n + 1
+    .endr
+    # pop TaskContext
+    addi sp, sp, 13*8
+    ret
+

os/src/task/switch.rs

@@ -0,0 +1,7 @@
+use super::TaskContext;
+
+global_asm!(include_str!("switch.S"));
+
+extern "C" {
+    pub fn __switch(current_task_cx: &usize, next_task_cx: &usize);
+}

os/src/trap/mod.rs

@@ -11,7 +11,6 @@ use riscv::register::{
     stval,
 };
 use crate::syscall::syscall;
-use crate::batch::run_next_app;
 
 global_asm!(include_str!("trap.S"));
 
@@ -34,11 +33,13 @@ pub fn trap_handler(cx: &mut TrapContext) -> &mut TrapContext {
         Trap::Exception(Exception::StoreFault) |
         Trap::Exception(Exception::StorePageFault) => {
             println!("[kernel] PageFault in application, core dumped.");
-            run_next_app();
+            panic!("[kernel] Cannot continue!");
+            //run_next_app();
         }
         Trap::Exception(Exception::IllegalInstruction) => {
             println!("[kernel] IllegalInstruction in application, core dumped.");
-            run_next_app();
+            panic!("[kernel] Cannot continue!");
+            //run_next_app();
         }
         _ => {
             panic!("Unsupported trap {:?}, stval = {:#x}!", scause.cause(), stval);

os/src/trap/trap.S

@@ -38,9 +38,6 @@ __alltraps:
     call trap_handler
 
 __restore:
-    # case1: start running app by __restore
-    # case2: back to U after handling trap
-    mv sp, a0
     # now sp->kernel stack(after allocated), sscratch->user stack
     # restore sstatus/sepc
     ld t0, 32*8(sp)

user/Makefile

@@ -1,5 +1,5 @@
 TARGET := riscv64gc-unknown-none-elf
-MODE := release
+MODE := debug
 APP_DIR := src/bin
 TARGET_DIR := target/$(TARGET)/$(MODE)
 APPS := $(wildcard $(APP_DIR)/*.rs)
@@ -9,7 +9,7 @@ BINS := $(patsubst $(APP_DIR)/%.rs, $(TARGET_DIR)/%.bin, $(APPS))
 OBJDUMP := rust-objdump --arch-name=riscv64
 OBJCOPY := rust-objcopy --binary-architecture=riscv64
 
-elf:
+elf: $(APPS)
 	@python3 build.py
 
 binary: elf

user/build.py

@@ -1,6 +1,6 @@
 import os
 
-base_address = 0x80040000
+base_address = 0x80100000
 step = 0x20000
 linker = 'src/linker.ld'
 
@@ -18,7 +18,7 @@ for app in apps:
             lines.append(line)
     with open(linker, 'w+') as f:
         f.writelines(lines)
-    os.system('cargo build --bin %s --release' % app)
+    os.system('cargo build --bin %s' % app)
     print('[build.py] application %s start with address %s' %(app, hex(base_address+step*app_id)))
     with open(linker, 'w+') as f:
         f.writelines(lines_before)

user/src/linker.ld

@@ -2,7 +2,7 @@
 OUTPUT_ARCH(riscv)
 ENTRY(_start)
 
-BASE_ADDRESS = 0x80040000;
+BASE_ADDRESS = 0x80100000;
 
 SECTIONS
 {