Schedule tasks to APs in aster-nix

kernel/src/lib.rs

@@ -35,6 +35,7 @@ use core::sync::atomic::Ordering;
 use ostd::{
     arch::qemu::{exit_qemu, QemuExitCode},
     boot,
+    cpu::PinCurrentCpu,
 };
 use process::Process;
 
@@ -83,7 +84,13 @@ pub fn main() {
     component::init_all(component::parse_metadata!()).unwrap();
     init();
     ostd::IN_BOOTSTRAP_CONTEXT.store(false, Ordering::Relaxed);
+
+    // Spawn all AP idle threads.
+    ostd::boot::smp::register_ap_entry(ap_init);
+
+    // Spawn the first kernel thread on BSP.
     Thread::spawn_kernel_thread(ThreadOptions::new(init_thread));
+    // Spawning functions in the bootstrap context will not return.
     unreachable!()
 }
 
@@ -100,6 +107,25 @@ pub fn init() {
     process::init();
 }
 
+fn ap_init() -> ! {
+    fn ap_idle_thread() {
+        let preempt_guard = ostd::task::disable_preempt();
+        let cpu_id = preempt_guard.current_cpu();
+        drop(preempt_guard);
+        log::info!("Kernel idle thread for CPU #{} started.", cpu_id);
+        loop {
+            Thread::yield_now();
+        }
+    }
+    let preempt_guard = ostd::task::disable_preempt();
+    let cpu_id = preempt_guard.current_cpu();
+    drop(preempt_guard);
+
+    Thread::spawn_kernel_thread(ThreadOptions::new(ap_idle_thread).cpu_affinity(cpu_id.into()));
+    // Spawning functions in the bootstrap context will not return.
+    unreachable!()
+}
+
 fn init_thread() {
     println!(
         "[kernel] Spawn init thread, tid = {}",

kernel/src/sched/priority_scheduler.rs

@@ -1,8 +1,9 @@
 // SPDX-License-Identifier: MPL-2.0
 
 use ostd::{
-    cpu::{num_cpus, PinCurrentCpu},
+    cpu::{num_cpus, CpuSet, PinCurrentCpu},
     task::{
+        disable_preempt,
         scheduler::{inject_scheduler, EnqueueFlags, LocalRunQueue, Scheduler, UpdateFlags},
         AtomicCpuId, Priority, Task,
     },
@@ -36,10 +37,31 @@ impl<T: PreemptSchedInfo> PreemptScheduler<T> {
         Self { rq }
     }
 
-    /// Selects a cpu for task to run on.
+    /// Selects a CPU for task to run on for the first time.
-    fn select_cpu(&self, _runnable: &Arc<T>) -> u32 {
+    fn select_cpu(&self, runnable: &Arc<T>) -> u32 {
-        // FIXME: adopt more reasonable policy once we fully enable SMP.
+        // If the CPU of a runnable task has been set before, keep scheduling
-        0
+        // the task to that one.
+        // TODO: Consider migrating tasks between CPUs for load balancing.
+        if let Some(cpu_id) = runnable.cpu().get() {
+            return cpu_id;
+        }
+
+        let preempt_guard = disable_preempt();
+        let mut selected = preempt_guard.current_cpu();
+        let mut minimum_load = usize::MAX;
+
+        for candidate in runnable.cpu_affinity().iter() {
+            let rq = self.rq[candidate].lock();
+            // A wild guess measuring the load of a runqueue. We assume that
+            // real-time tasks are 4-times as important as normal tasks.
+            let load = rq.real_time_entities.len() * 4 + rq.normal_entities.len();
+            if load < minimum_load {
+                selected = candidate as u32;
+                minimum_load = load;
+            }
+        }
+
+        selected
     }
 }
 
@@ -214,11 +236,15 @@ impl PreemptSchedInfo for Task {
     const REAL_TIME_TASK_PRIORITY: Self::PRIORITY = Priority::new(100);
 
     fn priority(&self) -> Self::PRIORITY {
-        self.priority()
+        self.schedule_info().priority
     }
 
     fn cpu(&self) -> &AtomicCpuId {
-        self.cpu()
+        &self.schedule_info().cpu
+    }
+
+    fn cpu_affinity(&self) -> &CpuSet {
+        &self.schedule_info().cpu_affinity
     }
 }
 
@@ -231,6 +257,8 @@ trait PreemptSchedInfo {
 
     fn cpu(&self) -> &AtomicCpuId;
 
+    fn cpu_affinity(&self) -> &CpuSet;
+
     fn is_real_time(&self) -> bool {
         self.priority() < Self::REAL_TIME_TASK_PRIORITY
     }

ostd/src/cpu/mod.rs

@@ -166,3 +166,11 @@ impl CpuSet {
         self.bitset.iter_ones()
     }
 }
+
+impl From<u32> for CpuSet {
+    fn from(cpu_id: u32) -> Self {
+        let mut set = Self::new_empty();
+        set.add(cpu_id);
+        set
+    }
+}

ostd/src/task/kernel_stack.rs

@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::{
+    mm::{kspace::KERNEL_PAGE_TABLE, FrameAllocOptions, Paddr, PageFlags, Segment, PAGE_SIZE},
+    prelude::*,
+};
+
+/// The kernel stack size of a task, specified in pages.
+///
+/// By default, we choose a rather large stack size.
+/// OSTD users can choose a smaller size by specifying
+/// the `OSTD_TASK_STACK_SIZE_IN_PAGES` environment variable
+/// at build time.
+pub static STACK_SIZE_IN_PAGES: u32 = parse_u32_or_default(
+    option_env!("OSTD_TASK_STACK_SIZE_IN_PAGES"),
+    DEFAULT_STACK_SIZE_IN_PAGES,
+);
+
+/// The default kernel stack size of a task, specified in pages.
+pub const DEFAULT_STACK_SIZE_IN_PAGES: u32 = 128;
+
+#[derive(Debug)]
+pub struct KernelStack {
+    segment: Segment,
+    has_guard_page: bool,
+}
+
+impl KernelStack {
+    pub fn new() -> Result<Self> {
+        Ok(Self {
+            segment: FrameAllocOptions::new(STACK_SIZE_IN_PAGES as usize).alloc_contiguous()?,
+            has_guard_page: false,
+        })
+    }
+
+    /// Generates a kernel stack with a guard page.
+    /// An additional page is allocated and be regarded as a guard page, which should not be accessed.  
+    pub fn new_with_guard_page() -> Result<Self> {
+        let stack_segment =
+            FrameAllocOptions::new(STACK_SIZE_IN_PAGES as usize + 1).alloc_contiguous()?;
+        // FIXME: modifying the the linear mapping is bad.
+        let page_table = KERNEL_PAGE_TABLE.get().unwrap();
+        let guard_page_vaddr = {
+            let guard_page_paddr = stack_segment.start_paddr();
+            crate::mm::paddr_to_vaddr(guard_page_paddr)
+        };
+        // SAFETY: the segment allocated is not used by others so we can protect it.
+        unsafe {
+            let vaddr_range = guard_page_vaddr..guard_page_vaddr + PAGE_SIZE;
+            page_table
+                .protect_flush_tlb(&vaddr_range, |p| p.flags -= PageFlags::RW)
+                .unwrap();
+        }
+        Ok(Self {
+            segment: stack_segment,
+            has_guard_page: true,
+        })
+    }
+
+    pub fn end_paddr(&self) -> Paddr {
+        self.segment.end_paddr()
+    }
+}
+
+impl Drop for KernelStack {
+    fn drop(&mut self) {
+        if self.has_guard_page {
+            // FIXME: modifying the the linear mapping is bad.
+            let page_table = KERNEL_PAGE_TABLE.get().unwrap();
+            let guard_page_vaddr = {
+                let guard_page_paddr = self.segment.start_paddr();
+                crate::mm::paddr_to_vaddr(guard_page_paddr)
+            };
+            // SAFETY: the segment allocated is not used by others so we can protect it.
+            unsafe {
+                let vaddr_range = guard_page_vaddr..guard_page_vaddr + PAGE_SIZE;
+                page_table
+                    .protect_flush_tlb(&vaddr_range, |p| p.flags |= PageFlags::RW)
+                    .unwrap();
+            }
+        }
+    }
+}
+
+const fn parse_u32_or_default(size: Option<&str>, default: u32) -> u32 {
+    match size {
+        Some(value) => parse_u32(value),
+        None => default,
+    }
+}
+
+const fn parse_u32(input: &str) -> u32 {
+    let mut output: u32 = 0;
+    let bytes = input.as_bytes();
+    let mut i = 0;
+    while i < bytes.len() {
+        let digit = (bytes[i] - b'0') as u32;
+        output = output * 10 + digit;
+        i += 1;
+    }
+    output
+}

ostd/src/task/mod.rs

@@ -3,15 +3,253 @@
 //! Tasks are the unit of code execution.
 
 pub(crate) mod atomic_mode;
+mod kernel_stack;
 mod preempt;
 mod processor;
 pub mod scheduler;
-#[allow(clippy::module_inception)]
-mod task;
 
+use core::{any::Any, cell::UnsafeCell};
+
+use kernel_stack::KernelStack;
 pub(crate) use preempt::cpu_local::reset_preempt_info;
+use processor::current_task;
 
 pub use self::{
     preempt::{disable_preempt, DisabledPreemptGuard},
-    task::{AtomicCpuId, Priority, Task, TaskAdapter, TaskContextApi, TaskOptions},
+    scheduler::info::{AtomicCpuId, Priority, TaskScheduleInfo},
 };
+pub(crate) use crate::arch::task::{context_switch, TaskContext};
+use crate::{cpu::CpuSet, prelude::*, user::UserSpace};
+
+/// A task that executes a function to the end.
+///
+/// Each task is associated with per-task data and an optional user space.
+/// If having a user space, the task can switch to the user space to
+/// execute user code. Multiple tasks can share a single user space.
+pub struct Task {
+    func: Box<dyn Fn() + Send + Sync>,
+    data: Box<dyn Any + Send + Sync>,
+    user_space: Option<Arc<UserSpace>>,
+    ctx: UnsafeCell<TaskContext>,
+    /// kernel stack, note that the top is SyscallFrame/TrapFrame
+    kstack: KernelStack,
+
+    schedule_info: TaskScheduleInfo,
+}
+
+// SAFETY: `UnsafeCell<TaskContext>` is not `Sync`. However, we only use it in `schedule()` where
+// we have exclusive access to the field.
+unsafe impl Sync for Task {}
+
+impl Task {
+    /// Gets the current task.
+    ///
+    /// It returns `None` if the function is called in the bootstrap context.
+    pub fn current() -> Option<Arc<Task>> {
+        current_task()
+    }
+
+    pub(super) fn ctx(&self) -> &UnsafeCell<TaskContext> {
+        &self.ctx
+    }
+
+    /// Yields execution so that another task may be scheduled.
+    ///
+    /// Note that this method cannot be simply named "yield" as the name is
+    /// a Rust keyword.
+    pub fn yield_now() {
+        scheduler::yield_now()
+    }
+
+    /// Runs the task.
+    ///
+    /// BUG: This method highly depends on the current scheduling policy.
+    pub fn run(self: &Arc<Self>) {
+        scheduler::run_new_task(self.clone());
+    }
+
+    /// Returns the task data.
+    pub fn data(&self) -> &Box<dyn Any + Send + Sync> {
+        &self.data
+    }
+
+    /// Get the attached scheduling information.
+    pub fn schedule_info(&self) -> &TaskScheduleInfo {
+        &self.schedule_info
+    }
+
+    /// Returns the user space of this task, if it has.
+    pub fn user_space(&self) -> Option<&Arc<UserSpace>> {
+        if self.user_space.is_some() {
+            Some(self.user_space.as_ref().unwrap())
+        } else {
+            None
+        }
+    }
+
+    /// Exits the current task.
+    ///
+    /// The task `self` must be the task that is currently running.
+    ///
+    /// **NOTE:** If there is anything left on the stack, it will be forgotten. This behavior may
+    /// lead to resource leakage.
+    fn exit(self: Arc<Self>) -> ! {
+        // `current_task()` still holds a strong reference, so nothing is destroyed at this point,
+        // neither is the kernel stack.
+        drop(self);
+        scheduler::exit_current();
+        unreachable!()
+    }
+}
+
+/// Options to create or spawn a new task.
+pub struct TaskOptions {
+    func: Option<Box<dyn Fn() + Send + Sync>>,
+    data: Option<Box<dyn Any + Send + Sync>>,
+    user_space: Option<Arc<UserSpace>>,
+    priority: Priority,
+    cpu_affinity: CpuSet,
+}
+
+impl TaskOptions {
+    /// Creates a set of options for a task.
+    pub fn new<F>(func: F) -> Self
+    where
+        F: Fn() + Send + Sync + 'static,
+    {
+        Self {
+            func: Some(Box::new(func)),
+            data: None,
+            user_space: None,
+            priority: Priority::normal(),
+            cpu_affinity: CpuSet::new_full(),
+        }
+    }
+
+    /// Sets the function that represents the entry point of the task.
+    pub fn func<F>(mut self, func: F) -> Self
+    where
+        F: Fn() + Send + Sync + 'static,
+    {
+        self.func = Some(Box::new(func));
+        self
+    }
+
+    /// Sets the data associated with the task.
+    pub fn data<T>(mut self, data: T) -> Self
+    where
+        T: Any + Send + Sync,
+    {
+        self.data = Some(Box::new(data));
+        self
+    }
+
+    /// Sets the user space associated with the task.
+    pub fn user_space(mut self, user_space: Option<Arc<UserSpace>>) -> Self {
+        self.user_space = user_space;
+        self
+    }
+
+    /// Sets the priority of the task.
+    pub fn priority(mut self, priority: Priority) -> Self {
+        self.priority = priority;
+        self
+    }
+
+    /// Sets the CPU affinity mask for the task.
+    ///
+    /// The `cpu_affinity` parameter represents
+    /// the desired set of CPUs to run the task on.
+    pub fn cpu_affinity(mut self, cpu_affinity: CpuSet) -> Self {
+        self.cpu_affinity = cpu_affinity;
+        self
+    }
+
+    /// Builds a new task without running it immediately.
+    pub fn build(self) -> Result<Arc<Task>> {
+        /// all task will entering this function
+        /// this function is mean to executing the task_fn in Task
+        extern "C" fn kernel_task_entry() {
+            let current_task = current_task()
+                .expect("no current task, it should have current task in kernel task entry");
+            current_task.func.call(());
+            current_task.exit();
+        }
+
+        let mut new_task = Task {
+            func: self.func.unwrap(),
+            data: self.data.unwrap(),
+            user_space: self.user_space,
+            ctx: UnsafeCell::new(TaskContext::default()),
+            kstack: KernelStack::new_with_guard_page()?,
+            schedule_info: TaskScheduleInfo {
+                cpu: AtomicCpuId::default(),
+                priority: self.priority,
+                cpu_affinity: self.cpu_affinity,
+            },
+        };
+
+        let ctx = new_task.ctx.get_mut();
+        ctx.set_instruction_pointer(kernel_task_entry as usize);
+        // We should reserve space for the return address in the stack, otherwise
+        // we will write across the page boundary due to the implementation of
+        // the context switch.
+        //
+        // According to the System V AMD64 ABI, the stack pointer should be aligned
+        // to at least 16 bytes. And a larger alignment is needed if larger arguments
+        // are passed to the function. The `kernel_task_entry` function does not
+        // have any arguments, so we only need to align the stack pointer to 16 bytes.
+        ctx.set_stack_pointer(crate::mm::paddr_to_vaddr(new_task.kstack.end_paddr() - 16));
+
+        Ok(Arc::new(new_task))
+    }
+
+    /// Builds a new task and run it immediately.
+    pub fn spawn(self) -> Result<Arc<Task>> {
+        let task = self.build()?;
+        task.run();
+        Ok(task)
+    }
+}
+
+/// Trait for manipulating the task context.
+pub trait TaskContextApi {
+    /// Sets instruction pointer
+    fn set_instruction_pointer(&mut self, ip: usize);
+
+    /// Gets instruction pointer
+    fn instruction_pointer(&self) -> usize;
+
+    /// Sets stack pointer
+    fn set_stack_pointer(&mut self, sp: usize);
+
+    /// Gets stack pointer
+    fn stack_pointer(&self) -> usize;
+}
+
+#[cfg(ktest)]
+mod test {
+    use crate::prelude::*;
+
+    #[ktest]
+    fn create_task() {
+        #[allow(clippy::eq_op)]
+        let task = || {
+            assert_eq!(1, 1);
+        };
+        let task_option = crate::task::TaskOptions::new(task)
+            .data(())
+            .build()
+            .unwrap();
+        task_option.run();
+    }
+
+    #[ktest]
+    fn spawn_task() {
+        #[allow(clippy::eq_op)]
+        let task = || {
+            assert_eq!(1, 1);
+        };
+        let _ = crate::task::TaskOptions::new(task).data(()).spawn();
+    }
+}

ostd/src/task/processor.rs

@@ -2,7 +2,7 @@
 
 use alloc::sync::Arc;
 
-use super::task::{context_switch, Task, TaskContext};
+use super::{context_switch, Task, TaskContext};
 use crate::cpu_local_cell;
 
 cpu_local_cell! {

ostd/src/task/scheduler/fifo_scheduler.rs

@@ -122,7 +122,7 @@ impl Default for FifoScheduler<Task> {
 
 impl FifoSchedInfo for Task {
     fn cpu(&self) -> &AtomicCpuId {
-        self.cpu()
+        &self.schedule_info().cpu
     }
 }
 

ostd/src/task/scheduler/info.rs

@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: MPL-2.0
+
+//! Scheduling related information in a task.
+
+use core::sync::atomic::{AtomicU32, Ordering};
+
+use crate::cpu::CpuSet;
+
+/// Fields of a task that OSTD will never touch.
+///
+/// The type ought to be defined by the OSTD user and injected into the task.
+/// They are not part of the dynamic task data because it's slower there for
+/// the user-defined scheduler to access. The better ways to let the user
+/// define them, such as
+/// [existential types](https://github.com/rust-lang/rfcs/pull/2492) do not
+/// exist yet. So we decide to define them in OSTD.
+pub struct TaskScheduleInfo {
+    /// Priority of the task.
+    pub priority: Priority,
+    /// The CPU that the task would like to be running on.
+    pub cpu: AtomicCpuId,
+    /// The CPUs that this task can run on.
+    pub cpu_affinity: CpuSet,
+}
+
+/// The priority of a real-time task.
+pub const REAL_TIME_TASK_PRIORITY: u16 = 100;
+
+/// The priority of a task.
+///
+/// Similar to Linux, a larger value represents a lower priority,
+/// with a range of 0 to 139. Priorities ranging from 0 to 99 are considered real-time,
+/// while those ranging from 100 to 139 are considered normal.
+#[derive(Copy, Clone, Eq, Ord, PartialEq, PartialOrd)]
+pub struct Priority(u16);
+
+impl Priority {
+    /// Creates a new `Priority` with the specified value.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the `val` is greater than 139.
+    pub const fn new(val: u16) -> Self {
+        assert!(val <= 139);
+        Self(val)
+    }
+
+    /// Returns a `Priority` representing the lowest priority (139).
+    pub const fn lowest() -> Self {
+        Self::new(139)
+    }
+
+    /// Returns a `Priority` representing a low priority.
+    pub const fn low() -> Self {
+        Self::new(110)
+    }
+
+    /// Returns a `Priority` representing a normal priority.
+    pub const fn normal() -> Self {
+        Self::new(100)
+    }
+
+    /// Returns a `Priority` representing a high priority.
+    pub const fn high() -> Self {
+        Self::new(10)
+    }
+
+    /// Returns a `Priority` representing the highest priority (0).
+    pub const fn highest() -> Self {
+        Self::new(0)
+    }
+
+    /// Sets the value of the `Priority`.
+    pub const fn set(&mut self, val: u16) {
+        self.0 = val;
+    }
+
+    /// Returns the value of the `Priority`.
+    pub const fn get(self) -> u16 {
+        self.0
+    }
+
+    /// Checks if the `Priority` is considered a real-time priority.
+    pub const fn is_real_time(&self) -> bool {
+        self.0 < REAL_TIME_TASK_PRIORITY
+    }
+}
+
+/// An atomic CPUID container.
+pub struct AtomicCpuId(AtomicU32);
+
+impl AtomicCpuId {
+    /// The null value of CPUID.
+    ///
+    /// An `AtomicCpuId` with `AtomicCpuId::NONE` as its inner value is empty.
+    const NONE: u32 = u32::MAX;
+
+    fn new(cpu_id: u32) -> Self {
+        Self(AtomicU32::new(cpu_id))
+    }
+
+    /// Sets the inner value of an `AtomicCpuId` if it's empty.
+    ///
+    /// The return value is a result indicating whether the new value was written
+    /// and containing the previous value.
+    pub fn set_if_is_none(&self, cpu_id: u32) -> core::result::Result<u32, u32> {
+        self.0
+            .compare_exchange(Self::NONE, cpu_id, Ordering::Relaxed, Ordering::Relaxed)
+    }
+
+    /// Sets the inner value of an `AtomicCpuId` to `AtomicCpuId::NONE`, i.e. makes
+    /// an `AtomicCpuId` empty.
+    pub fn set_to_none(&self) {
+        self.0.store(Self::NONE, Ordering::Relaxed);
+    }
+
+    /// Gets the inner value of an `AtomicCpuId`.
+    pub fn get(&self) -> Option<u32> {
+        let val = self.0.load(Ordering::Relaxed);
+        if val == Self::NONE {
+            None
+        } else {
+            Some(val)
+        }
+    }
+}
+
+impl Default for AtomicCpuId {
+    fn default() -> Self {
+        Self::new(Self::NONE)
+    }
+}

ostd/src/task/scheduler/mod.rs

@@ -6,12 +6,13 @@
 //! and provides useful functions for controlling the execution flow.
 
 mod fifo_scheduler;
+pub mod info;
 
 use core::sync::atomic::{AtomicBool, Ordering};
 
 use spin::Once;
 
-use super::{preempt::cpu_local, processor, task::Task};
+use super::{preempt::cpu_local, processor, Task};
 use crate::{arch::timer, cpu::PinCurrentCpu, prelude::*, task::disable_preempt};
 
 /// Injects a scheduler implementation into framework.

ostd/src/task/task/mod.rs

@@ -1,405 +0,0 @@
-// SPDX-License-Identifier: MPL-2.0
-
-// FIXME: the `intrusive_adapter` macro will generate methods without docs.
-// So we temporary allow missing_docs for this module.
-#![allow(missing_docs)]
-
-mod priority;
-
-use core::{
-    any::Any,
-    cell::UnsafeCell,
-    sync::atomic::{AtomicU32, Ordering},
-};
-
-use intrusive_collections::{intrusive_adapter, LinkedListAtomicLink};
-pub use priority::Priority;
-
-use super::{processor::current_task, scheduler};
-pub(crate) use crate::arch::task::{context_switch, TaskContext};
-use crate::{
-    cpu::CpuSet,
-    mm::{kspace::KERNEL_PAGE_TABLE, FrameAllocOptions, Paddr, PageFlags, Segment, PAGE_SIZE},
-    prelude::*,
-    user::UserSpace,
-};
-
-/// The kernel stack size of a task, specified in pages.
-///
-/// By default, we choose a rather large stack size.
-/// OSTD users can choose a smaller size by specifying
-/// the `OSTD_TASK_STACK_SIZE_IN_PAGES` environment variable
-/// at build time.
-pub static STACK_SIZE_IN_PAGES: u32 = parse_u32_or_default(
-    option_env!("OSTD_TASK_STACK_SIZE_IN_PAGES"),
-    DEFAULT_STACK_SIZE_IN_PAGES,
-);
-
-/// The default kernel stack size of a task, specified in pages.
-pub const DEFAULT_STACK_SIZE_IN_PAGES: u32 = 128;
-
-const fn parse_u32_or_default(size: Option<&str>, default: u32) -> u32 {
-    match size {
-        Some(value) => parse_u32(value),
-        None => default,
-    }
-}
-
-const fn parse_u32(input: &str) -> u32 {
-    let mut output: u32 = 0;
-    let bytes = input.as_bytes();
-    let mut i = 0;
-    while i < bytes.len() {
-        let digit = (bytes[i] - b'0') as u32;
-        output = output * 10 + digit;
-        i += 1;
-    }
-    output
-}
-
-/// Trait for manipulating the task context.
-pub trait TaskContextApi {
-    /// Sets instruction pointer
-    fn set_instruction_pointer(&mut self, ip: usize);
-
-    /// Gets instruction pointer
-    fn instruction_pointer(&self) -> usize;
-
-    /// Sets stack pointer
-    fn set_stack_pointer(&mut self, sp: usize);
-
-    /// Gets stack pointer
-    fn stack_pointer(&self) -> usize;
-}
-
-#[derive(Debug)]
-pub struct KernelStack {
-    segment: Segment,
-    has_guard_page: bool,
-}
-
-impl KernelStack {
-    pub fn new() -> Result<Self> {
-        Ok(Self {
-            segment: FrameAllocOptions::new(STACK_SIZE_IN_PAGES as usize).alloc_contiguous()?,
-            has_guard_page: false,
-        })
-    }
-
-    /// Generates a kernel stack with a guard page.
-    /// An additional page is allocated and be regarded as a guard page, which should not be accessed.  
-    pub fn new_with_guard_page() -> Result<Self> {
-        let stack_segment =
-            FrameAllocOptions::new(STACK_SIZE_IN_PAGES as usize + 1).alloc_contiguous()?;
-        // FIXME: modifying the the linear mapping is bad.
-        let page_table = KERNEL_PAGE_TABLE.get().unwrap();
-        let guard_page_vaddr = {
-            let guard_page_paddr = stack_segment.start_paddr();
-            crate::mm::paddr_to_vaddr(guard_page_paddr)
-        };
-        // SAFETY: the segment allocated is not used by others so we can protect it.
-        unsafe {
-            let vaddr_range = guard_page_vaddr..guard_page_vaddr + PAGE_SIZE;
-            page_table
-                .protect_flush_tlb(&vaddr_range, |p| p.flags -= PageFlags::RW)
-                .unwrap();
-        }
-        Ok(Self {
-            segment: stack_segment,
-            has_guard_page: true,
-        })
-    }
-
-    pub fn end_paddr(&self) -> Paddr {
-        self.segment.end_paddr()
-    }
-}
-
-impl Drop for KernelStack {
-    fn drop(&mut self) {
-        if self.has_guard_page {
-            // FIXME: modifying the the linear mapping is bad.
-            let page_table = KERNEL_PAGE_TABLE.get().unwrap();
-            let guard_page_vaddr = {
-                let guard_page_paddr = self.segment.start_paddr();
-                crate::mm::paddr_to_vaddr(guard_page_paddr)
-            };
-            // SAFETY: the segment allocated is not used by others so we can protect it.
-            unsafe {
-                let vaddr_range = guard_page_vaddr..guard_page_vaddr + PAGE_SIZE;
-                page_table
-                    .protect_flush_tlb(&vaddr_range, |p| p.flags |= PageFlags::RW)
-                    .unwrap();
-            }
-        }
-    }
-}
-
-/// An atomic CPUID container.
-pub struct AtomicCpuId(AtomicU32);
-
-impl AtomicCpuId {
-    /// The null value of CPUID.
-    ///
-    /// An `AtomicCpuId` with `AtomicCpuId::NONE` as its inner value is empty.
-    const NONE: u32 = u32::MAX;
-
-    fn new(cpu_id: u32) -> Self {
-        Self(AtomicU32::new(cpu_id))
-    }
-
-    /// Sets the inner value of an `AtomicCpuId` if it's empty.
-    ///
-    /// The return value is a result indicating whether the new value was written
-    /// and containing the previous value.
-    pub fn set_if_is_none(&self, cpu_id: u32) -> core::result::Result<u32, u32> {
-        self.0
-            .compare_exchange(Self::NONE, cpu_id, Ordering::Relaxed, Ordering::Relaxed)
-    }
-
-    /// Sets the inner value of an `AtomicCpuId` to `AtomicCpuId::NONE`, i.e. makes
-    /// an `AtomicCpuId` empty.
-    pub fn set_to_none(&self) {
-        self.0.store(Self::NONE, Ordering::Relaxed);
-    }
-}
-
-impl Default for AtomicCpuId {
-    fn default() -> Self {
-        Self::new(Self::NONE)
-    }
-}
-
-/// A task that executes a function to the end.
-///
-/// Each task is associated with per-task data and an optional user space.
-/// If having a user space, the task can switch to the user space to
-/// execute user code. Multiple tasks can share a single user space.
-pub struct Task {
-    func: Box<dyn Fn() + Send + Sync>,
-    data: Box<dyn Any + Send + Sync>,
-    user_space: Option<Arc<UserSpace>>,
-    ctx: UnsafeCell<TaskContext>,
-    /// kernel stack, note that the top is SyscallFrame/TrapFrame
-    kstack: KernelStack,
-    link: LinkedListAtomicLink,
-    cpu: AtomicCpuId,
-    priority: Priority,
-    // TODO: add multiprocessor support
-    #[allow(dead_code)]
-    cpu_affinity: CpuSet,
-}
-
-// TaskAdapter struct is implemented for building relationships between doubly linked list and Task struct
-intrusive_adapter!(pub TaskAdapter = Arc<Task>: Task { link: LinkedListAtomicLink });
-
-// SAFETY: `UnsafeCell<TaskContext>` is not `Sync`. However, we only use it in `schedule()` where
-// we have exclusive access to the field.
-unsafe impl Sync for Task {}
-
-impl Task {
-    /// Gets the current task.
-    ///
-    /// It returns `None` if the function is called in the bootstrap context.
-    pub fn current() -> Option<Arc<Task>> {
-        current_task()
-    }
-
-    pub(super) fn ctx(&self) -> &UnsafeCell<TaskContext> {
-        &self.ctx
-    }
-
-    /// Yields execution so that another task may be scheduled.
-    ///
-    /// Note that this method cannot be simply named "yield" as the name is
-    /// a Rust keyword.
-    pub fn yield_now() {
-        scheduler::yield_now()
-    }
-
-    /// Runs the task.
-    ///
-    /// BUG: This method highly depends on the current scheduling policy.
-    pub fn run(self: &Arc<Self>) {
-        scheduler::run_new_task(self.clone());
-    }
-
-    /// Returns the task data.
-    pub fn data(&self) -> &Box<dyn Any + Send + Sync> {
-        &self.data
-    }
-
-    /// Returns the user space of this task, if it has.
-    pub fn user_space(&self) -> Option<&Arc<UserSpace>> {
-        if self.user_space.is_some() {
-            Some(self.user_space.as_ref().unwrap())
-        } else {
-            None
-        }
-    }
-
-    // Returns the cpu of this task.
-    pub fn cpu(&self) -> &AtomicCpuId {
-        &self.cpu
-    }
-
-    /// Returns the priority.
-    pub fn priority(&self) -> Priority {
-        self.priority
-    }
-
-    /// Exits the current task.
-    ///
-    /// The task `self` must be the task that is currently running.
-    ///
-    /// **NOTE:** If there is anything left on the stack, it will be forgotten. This behavior may
-    /// lead to resource leakage.
-    fn exit(self: Arc<Self>) -> ! {
-        // `current_task()` still holds a strong reference, so nothing is destroyed at this point,
-        // neither is the kernel stack.
-        drop(self);
-        scheduler::exit_current();
-        unreachable!()
-    }
-
-    /// Checks if the task has a real-time priority.
-    pub fn is_real_time(&self) -> bool {
-        self.priority.is_real_time()
-    }
-}
-
-/// Options to create or spawn a new task.
-pub struct TaskOptions {
-    func: Option<Box<dyn Fn() + Send + Sync>>,
-    data: Option<Box<dyn Any + Send + Sync>>,
-    user_space: Option<Arc<UserSpace>>,
-    priority: Priority,
-    cpu_affinity: CpuSet,
-}
-
-impl TaskOptions {
-    /// Creates a set of options for a task.
-    pub fn new<F>(func: F) -> Self
-    where
-        F: Fn() + Send + Sync + 'static,
-    {
-        Self {
-            func: Some(Box::new(func)),
-            data: None,
-            user_space: None,
-            priority: Priority::normal(),
-            cpu_affinity: CpuSet::new_full(),
-        }
-    }
-
-    /// Sets the function that represents the entry point of the task.
-    pub fn func<F>(mut self, func: F) -> Self
-    where
-        F: Fn() + Send + Sync + 'static,
-    {
-        self.func = Some(Box::new(func));
-        self
-    }
-
-    /// Sets the data associated with the task.
-    pub fn data<T>(mut self, data: T) -> Self
-    where
-        T: Any + Send + Sync,
-    {
-        self.data = Some(Box::new(data));
-        self
-    }
-
-    /// Sets the user space associated with the task.
-    pub fn user_space(mut self, user_space: Option<Arc<UserSpace>>) -> Self {
-        self.user_space = user_space;
-        self
-    }
-
-    /// Sets the priority of the task.
-    pub fn priority(mut self, priority: Priority) -> Self {
-        self.priority = priority;
-        self
-    }
-
-    /// Sets the CPU affinity mask for the task.
-    ///
-    /// The `cpu_affinity` parameter represents
-    /// the desired set of CPUs to run the task on.
-    pub fn cpu_affinity(mut self, cpu_affinity: CpuSet) -> Self {
-        self.cpu_affinity = cpu_affinity;
-        self
-    }
-
-    /// Builds a new task without running it immediately.
-    pub fn build(self) -> Result<Arc<Task>> {
-        /// all task will entering this function
-        /// this function is mean to executing the task_fn in Task
-        extern "C" fn kernel_task_entry() {
-            let current_task = current_task()
-                .expect("no current task, it should have current task in kernel task entry");
-            current_task.func.call(());
-            current_task.exit();
-        }
-
-        let mut new_task = Task {
-            func: self.func.unwrap(),
-            data: self.data.unwrap(),
-            user_space: self.user_space,
-            ctx: UnsafeCell::new(TaskContext::default()),
-            kstack: KernelStack::new_with_guard_page()?,
-            cpu: AtomicCpuId::default(),
-            link: LinkedListAtomicLink::new(),
-            priority: self.priority,
-            cpu_affinity: self.cpu_affinity,
-        };
-
-        let ctx = new_task.ctx.get_mut();
-        ctx.set_instruction_pointer(kernel_task_entry as usize);
-        // We should reserve space for the return address in the stack, otherwise
-        // we will write across the page boundary due to the implementation of
-        // the context switch.
-        //
-        // According to the System V AMD64 ABI, the stack pointer should be aligned
-        // to at least 16 bytes. And a larger alignment is needed if larger arguments
-        // are passed to the function. The `kernel_task_entry` function does not
-        // have any arguments, so we only need to align the stack pointer to 16 bytes.
-        ctx.set_stack_pointer(crate::mm::paddr_to_vaddr(new_task.kstack.end_paddr() - 16));
-
-        Ok(Arc::new(new_task))
-    }
-
-    /// Builds a new task and run it immediately.
-    pub fn spawn(self) -> Result<Arc<Task>> {
-        let task = self.build()?;
-        task.run();
-        Ok(task)
-    }
-}
-
-#[cfg(ktest)]
-mod test {
-    use crate::prelude::*;
-
-    #[ktest]
-    fn create_task() {
-        #[allow(clippy::eq_op)]
-        let task = || {
-            assert_eq!(1, 1);
-        };
-        let task_option = crate::task::TaskOptions::new(task)
-            .data(())
-            .build()
-            .unwrap();
-        task_option.run();
-    }
-
-    #[ktest]
-    fn spawn_task() {
-        #[allow(clippy::eq_op)]
-        let task = || {
-            assert_eq!(1, 1);
-        };
-        let _ = crate::task::TaskOptions::new(task).data(()).spawn();
-    }
-}

ostd/src/task/task/priority.rs

@@ -1,63 +0,0 @@
-// SPDX-License-Identifier: MPL-2.0
-
-pub const REAL_TIME_TASK_PRIORITY: u16 = 100;
-
-/// The priority of a task.
-///
-/// Similar to Linux, a larger value represents a lower priority,
-/// with a range of 0 to 139. Priorities ranging from 0 to 99 are considered real-time,
-/// while those ranging from 100 to 139 are considered normal.
-#[derive(Copy, Clone, Eq, Ord, PartialEq, PartialOrd)]
-pub struct Priority(u16);
-
-impl Priority {
-    /// Creates a new `Priority` with the specified value.
-    ///
-    /// # Panics
-    ///
-    /// Panics if the `val` is greater than 139.
-    pub const fn new(val: u16) -> Self {
-        assert!(val <= 139);
-        Self(val)
-    }
-
-    /// Returns a `Priority` representing the lowest priority (139).
-    pub const fn lowest() -> Self {
-        Self::new(139)
-    }
-
-    /// Returns a `Priority` representing a low priority.
-    pub const fn low() -> Self {
-        Self::new(110)
-    }
-
-    /// Returns a `Priority` representing a normal priority.
-    pub const fn normal() -> Self {
-        Self::new(100)
-    }
-
-    /// Returns a `Priority` representing a high priority.
-    pub const fn high() -> Self {
-        Self::new(10)
-    }
-
-    /// Returns a `Priority` representing the highest priority (0).
-    pub const fn highest() -> Self {
-        Self::new(0)
-    }
-
-    /// Sets the value of the `Priority`.
-    pub const fn set(&mut self, val: u16) {
-        self.0 = val;
-    }
-
-    /// Returns the value of the `Priority`.
-    pub const fn get(self) -> u16 {
-        self.0
-    }
-
-    /// Checks if the `Priority` is considered a real-time priority.
-    pub const fn is_real_time(&self) -> bool {
-        self.0 < REAL_TIME_TASK_PRIORITY
-    }
-}