Merge recent patch on ch3.

.gitignore

@@ -3,6 +3,7 @@ os/target/*
 os/.idea/*
 os/Cargo.lock
 os/src/link_app.S
+os/last-*
 user/target/*
 user/.idea/*
 user/Cargo.lock

README.md

@@ -1,2 +1,12 @@
 # rCore-Tutorial-v3
-rCore-Tutorial version 3.
+rCore-Tutorial version 3.x
+
+## Dependency
+
+### Binaries
+
+* rustc 1.56.0-nightly (b03ccace5 2021-08-24)
+
+* qemu: 5.0.0
+
+* rustsbi: qemu[7d71bfb7] k210[563144b0]

os/Makefile

@@ -29,12 +29,19 @@ OBJCOPY := rust-objcopy --binary-architecture=riscv64
 # Disassembly
 DISASM ?= -x
 
-build: env $(KERNEL_BIN)
+build: env switch-check $(KERNEL_BIN)
+
+switch-check:
+ifeq ($(BOARD), qemu)
+	(which last-qemu) || (rm last-k210 -f && touch last-qemu && make clean)
+else ifeq ($(BOARD), k210)
+	(which last-k210) || (rm last-qemu -f && touch last-k210 && make clean)
+endif
 
 env:
 	rustup component add rust-src
 	rustup component add llvm-tools-preview
-	cargo install cargo-binutils --vers ~0.2
+	cargo install cargo-binutils --vers =0.3.3
 	rustup target add riscv64gc-unknown-none-elf
 
 $(KERNEL_BIN): kernel
@@ -85,4 +92,4 @@ debug: build
 		tmux split-window -h "riscv64-unknown-elf-gdb -ex 'file $(KERNEL_ELF)' -ex 'set arch riscv:rv64' -ex 'target remote localhost:1234'" && \
 		tmux -2 attach-session -d
 
-.PHONY: build env kernel clean disasm disasm-vim run-inner
+.PHONY: build env kernel clean disasm disasm-vim run-inner switch-check

os/src/loader.rs

@@ -1,13 +1,14 @@
 use crate::trap::TrapContext;
-use crate::task::TaskContext;
 use crate::config::*;
 
 #[repr(align(4096))]
+#[derive(Copy, Clone)]
 struct KernelStack {
     data: [u8; KERNEL_STACK_SIZE],
 }
 
 #[repr(align(4096))]
+#[derive(Copy, Clone)]
 struct UserStack {
     data: [u8; USER_STACK_SIZE],
 }
@@ -26,14 +27,10 @@ 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 {
-        unsafe {
+    pub fn push_context(&self, trap_cx: TrapContext) -> usize {
         let trap_cx_ptr = (self.get_sp() - core::mem::size_of::<TrapContext>()) as *mut TrapContext;
-            *trap_cx_ptr = trap_cx;
-            let task_cx_ptr = (trap_cx_ptr as usize - core::mem::size_of::<TaskContext>()) as *mut TaskContext;
-            *task_cx_ptr = task_cx;
-            task_cx_ptr.as_mut().unwrap()
-        }
+        unsafe { *trap_cx_ptr = trap_cx; }
+        trap_cx_ptr as usize
     }
 }
 
@@ -60,7 +57,7 @@ pub fn load_apps() {
         core::slice::from_raw_parts(num_app_ptr.add(1), num_app + 1)
     };
     // clear i-cache first
-    unsafe { llvm_asm!("fence.i" :::: "volatile"); }
+    unsafe { asm!("fence.i"); }
     // load apps
     for i in 0..num_app {
         let base_i = get_base_i(i);
@@ -79,9 +76,8 @@ pub fn load_apps() {
     }
 }
 
-pub fn init_app_cx(app_id: usize) -> &'static TaskContext {
+pub fn init_app_cx(app_id: usize) -> usize {
     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

@@ -1,9 +1,8 @@
 #![no_std]
 #![no_main]
 #![feature(global_asm)]
-#![feature(llvm_asm)]
+#![feature(asm)]
 #![feature(panic_info_message)]
-#![feature(const_in_array_repeat_expressions)]
 
 #[macro_use]
 mod console;
@@ -14,6 +13,7 @@ mod trap;
 mod loader;
 mod config;
 mod task;
+mod sync;
 
 global_asm!(include_str!("entry.asm"));
 global_asm!(include_str!("link_app.S"));
@@ -23,9 +23,12 @@ fn clear_bss() {
         fn sbss();
         fn ebss();
     }
-    (sbss as usize..ebss as usize).for_each(|a| {
-        unsafe { (a as *mut u8).write_volatile(0) }
-    });
+    unsafe {
+        core::slice::from_raw_parts_mut(
+            sbss as usize as *mut u8,
+            ebss as usize - sbss as usize,
+        ).fill(0);
+    }
 }
 
 #[no_mangle]

os/src/sbi.rs

@@ -14,11 +14,12 @@ const SBI_SHUTDOWN: usize = 8;
 fn sbi_call(which: usize, arg0: usize, arg1: usize, arg2: usize) -> usize {
     let mut ret;
     unsafe {
-        llvm_asm!("ecall"
-            : "={x10}" (ret)
-            : "{x10}" (arg0), "{x11}" (arg1), "{x12}" (arg2), "{x17}" (which)
-            : "memory"
-            : "volatile"
+        asm!(
+            "ecall",
+            inlateout("x10") arg0 => ret,
+            in("x11") arg1,
+            in("x12") arg2,
+            in("x17") which,
         );
     }
     ret

os/src/sync/mod.rs

@@ -0,0 +1,3 @@
+mod up;
+
+pub use up::UPSafeCell;

os/src/sync/up.rs

@@ -0,0 +1,27 @@
+use core::cell::{RefCell, RefMut};
+
+/// Wrap a static data structure inside it so that we are
+/// able to access it without any `unsafe`.
+///
+/// We should only use it in uniprocessor.
+///
+/// In order to get mutable reference of inner data, call
+/// `exclusive_access`.
+pub struct UPSafeCell<T> {
+    /// inner data
+    inner: RefCell<T>,
+}
+
+unsafe impl<T> Sync for UPSafeCell<T> {}
+
+impl<T> UPSafeCell<T> {
+    /// User is responsible to guarantee that inner struct is only used in
+    /// uniprocessor.
+    pub unsafe fn new(value: T) -> Self {
+        Self { inner: RefCell::new(value) }
+    }
+    /// Panic if the data has been borrowed.
+    pub fn exclusive_access(&self) -> RefMut<'_, T> {
+        self.inner.borrow_mut()
+    }
+}

os/src/task/context.rs

@@ -1,14 +1,24 @@
+#[derive(Copy, Clone)]
 #[repr(C)]
 pub struct TaskContext {
     ra: usize,
+    sp: usize,
     s: [usize; 12],
 }
 
 impl TaskContext {
-    pub fn goto_restore() -> Self {
+    pub fn zero_init() -> Self {
+        Self {
+            ra: 0,
+            sp: 0,
+            s: [0; 12],
+        }
+    }
+    pub fn goto_restore(kstack_ptr: usize) -> Self {
         extern "C" { fn __restore(); }
         Self {
             ra: __restore as usize,
+            sp: kstack_ptr,
             s: [0; 12],
         }
     }

os/src/task/mod.rs

@@ -4,16 +4,16 @@ mod task;
 
 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;
 use task::{TaskControlBlock, TaskStatus};
+use crate::sync::UPSafeCell;
 
 pub use context::TaskContext;
 
 pub struct TaskManager {
     num_app: usize,
-    inner: RefCell<TaskManagerInner>,
+    inner: UPSafeCell<TaskManagerInner>,
 }
 
 struct TaskManagerInner {
@@ -21,56 +21,62 @@ struct TaskManagerInner {
     current_task: 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, task_status: TaskStatus::UnInit };
+            TaskControlBlock {
+                task_cx: TaskContext::zero_init(),
+                task_status: TaskStatus::UnInit
+            };
             MAX_APP_NUM
         ];
         for i in 0..num_app {
-            tasks[i].task_cx_ptr = init_app_cx(i) as * const _ as usize;
+            tasks[i].task_cx = TaskContext::goto_restore(init_app_cx(i));
             tasks[i].task_status = TaskStatus::Ready;
         }
         TaskManager {
             num_app,
-            inner: RefCell::new(TaskManagerInner {
+            inner: unsafe { UPSafeCell::new(TaskManagerInner {
                 tasks,
                 current_task: 0,
-            }),
+            })},
         }
     };
 }
 
 impl TaskManager {
-    fn run_first_task(&self) {
-        self.inner.borrow_mut().tasks[0].task_status = TaskStatus::Running;
-        let next_task_cx_ptr2 = self.inner.borrow().tasks[0].get_task_cx_ptr2();
-        let _unused: usize = 0;
+    fn run_first_task(&self) -> ! {
+        let mut inner = self.inner.exclusive_access();
+        let task0 = &mut inner.tasks[0];
+        task0.task_status = TaskStatus::Running;
+        let next_task_cx_ptr = &task0.task_cx as *const TaskContext;
+        drop(inner);
+        let mut _unused = TaskContext::zero_init();
+        // before this, we should drop local variables that must be dropped manually
         unsafe {
             __switch(
-                &_unused as *const _,
-                next_task_cx_ptr2,
+                &mut _unused as *mut TaskContext,
+                next_task_cx_ptr,
             );
         }
+        panic!("unreachable in run_first_task!");
     }
 
     fn mark_current_suspended(&self) {
-        let mut inner = self.inner.borrow_mut();
+        let mut inner = self.inner.exclusive_access();
         let current = inner.current_task;
         inner.tasks[current].task_status = TaskStatus::Ready;
     }
 
     fn mark_current_exited(&self) {
-        let mut inner = self.inner.borrow_mut();
+        let mut inner = self.inner.exclusive_access();
         let current = inner.current_task;
         inner.tasks[current].task_status = TaskStatus::Exited;
     }
 
     fn find_next_task(&self) -> Option<usize> {
-        let inner = self.inner.borrow();
+        let inner = self.inner.exclusive_access();
         let current = inner.current_task;
         (current + 1..current + self.num_app + 1)
             .map(|id| id % self.num_app)
@@ -81,19 +87,21 @@ impl TaskManager {
 
     fn run_next_task(&self) {
         if let Some(next) = self.find_next_task() {
-            let mut inner = self.inner.borrow_mut();
+            let mut inner = self.inner.exclusive_access();
             let current = inner.current_task;
             inner.tasks[next].task_status = TaskStatus::Running;
             inner.current_task = next;
-            let current_task_cx_ptr2 = inner.tasks[current].get_task_cx_ptr2();
-            let next_task_cx_ptr2 = inner.tasks[next].get_task_cx_ptr2();
-            core::mem::drop(inner);
+            let current_task_cx_ptr = &mut inner.tasks[current].task_cx as *mut TaskContext;
+            let next_task_cx_ptr = &inner.tasks[next].task_cx as *const TaskContext;
+            drop(inner);
+            // before this, we should drop local variables that must be dropped manually
             unsafe {
                 __switch(
-                    current_task_cx_ptr2,
-                    next_task_cx_ptr2,
+                    current_task_cx_ptr,
+                    next_task_cx_ptr,
                 );
             }
+            // go back to user mode
         } else {
             panic!("All applications completed!");
         }

os/src/task/switch.S

@@ -1,37 +1,34 @@
 .altmacro
 .macro SAVE_SN n
-    sd s\n, (\n+1)*8(sp)
+    sd s\n, (\n+2)*8(a0)
 .endm
 .macro LOAD_SN n
-    ld s\n, (\n+1)*8(sp)
+    ld s\n, (\n+2)*8(a1)
 .endm
     .section .text
     .globl __switch
 __switch:
     # __switch(
-    #     current_task_cx_ptr2: &*const TaskContext,
-    #     next_task_cx_ptr2: &*const TaskContext
+    #     current_task_cx_ptr: *mut TaskContext,
+    #     next_task_cx_ptr: *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)
+    # save kernel stack of current task
+    sd sp, 8(a0)
+    # save ra & s0~s11 of current execution
+    sd ra, 0(a0)
     .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)
+    # restore ra & s0~s11 of next execution
+    ld ra, 0(a1)
     .set n, 0
     .rept 12
         LOAD_SN %n
         .set n, n + 1
     .endr
-    # pop TaskContext
-    addi sp, sp, 13*8
+    # restore kernel stack of next task
+    ld sp, 8(a1)
     ret
 

os/src/task/switch.rs

@@ -1,8 +1,10 @@
 global_asm!(include_str!("switch.S"));
 
+use super::TaskContext;
+
 extern "C" {
     pub fn __switch(
-        current_task_cx_ptr2: *const usize,
-        next_task_cx_ptr2: *const usize
+        current_task_cx_ptr: *mut TaskContext,
+        next_task_cx_ptr: *const TaskContext
     );
 }

os/src/task/task.rs

@@ -1,12 +1,9 @@
-pub struct TaskControlBlock {
-    pub task_cx_ptr: usize,
-    pub task_status: TaskStatus,
-}
+use super::TaskContext;
 
-impl TaskControlBlock {
-    pub fn get_task_cx_ptr2(&self) -> *const usize {
-        &self.task_cx_ptr as *const usize
-    }
+#[derive(Copy, Clone)]
+pub struct TaskControlBlock {
+    pub task_status: TaskStatus,
+    pub task_cx: TaskContext,
 }
 
 #[derive(Copy, Clone, PartialEq)]

rust-toolchain

@@ -1 +1 @@
-nightly-2021-01-30
+nightly-2021-10-15

user/src/lib.rs

@@ -1,5 +1,5 @@
 #![no_std]
-#![feature(llvm_asm)]
+#![feature(asm)]
 #![feature(linkage)]
 #![feature(panic_info_message)]
 

user/src/syscall.rs

@@ -5,11 +5,12 @@ const SYSCALL_YIELD: usize = 124;
 fn syscall(id: usize, args: [usize; 3]) -> isize {
     let mut ret: isize;
     unsafe {
-        llvm_asm!("ecall"
-            : "={x10}" (ret)
-            : "{x10}" (args[0]), "{x11}" (args[1]), "{x12}" (args[2]), "{x17}" (id)
-            : "memory"
-            : "volatile"
+        asm!(
+            "ecall",
+            inlateout("x10") args[0] => ret,
+            in("x11") args[1],
+            in("x12") args[2],
+            in("x17") id
         );
     }
     ret