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Fix the kernel stack alignment
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commit
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@ -1,5 +1,4 @@
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// SPDX-License-Identifier: MPL-2.0
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use core::mem::size_of;
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use intrusive_collections::{intrusive_adapter, LinkedListAtomicLink};
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@ -101,6 +100,10 @@ impl Drop for KernelStack {
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}
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/// A task that executes a function to the end.
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///
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/// Each task is associated with per-task data and an optional user space.
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/// If having a user space, the task can switch to the user space to
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/// execute user code. Multiple tasks can share a single user space.
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pub struct Task {
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func: Box<dyn Fn() + Send + Sync>,
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data: Box<dyn Any + Send + Sync>,
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@ -251,11 +254,11 @@ impl TaskOptions {
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self
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}
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/// Builds a new task but not run it immediately.
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/// Build a new task without running it immediately.
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pub fn build(self) -> Result<Arc<Task>> {
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/// all task will entering this function
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/// this function is mean to executing the task_fn in Task
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fn kernel_task_entry() {
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extern "sysv64" fn kernel_task_entry() {
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let current_task = current_task()
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.expect("no current task, it should have current task in kernel task entry");
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current_task.func.call(());
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@ -278,52 +281,23 @@ impl TaskOptions {
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result.task_inner.lock().task_status = TaskStatus::Runnable;
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result.task_inner.lock().ctx.rip = kernel_task_entry as usize;
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// Subtract 8 bytes to reserve space for the return address, otherwise
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// we will write across the page bondary.
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// We should reserve space for the return address in the stack, otherwise
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// we will write across the page boundary due to the implementation of
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// the context switch.
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// According to the System V AMD64 ABI, the stack pointer should be aligned
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// to at least 16 bytes. And a larger alignment is needed if larger arguments
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// are passed to the function. The `kernel_task_entry` function does not
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// have any arguments, so we only need to align the stack pointer to 16 bytes.
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result.task_inner.lock().ctx.regs.rsp =
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(crate::vm::paddr_to_vaddr(result.kstack.end_paddr() - size_of::<u64>())) as u64;
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(crate::vm::paddr_to_vaddr(result.kstack.end_paddr() - 16)) as u64;
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Ok(Arc::new(result))
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}
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/// Builds a new task and run it immediately.
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///
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/// Each task is associated with a per-task data and an optional user space.
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/// If having a user space, then the task can switch to the user space to
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/// execute user code. Multiple tasks can share a single user space.
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/// Build a new task and run it immediately.
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pub fn spawn(self) -> Result<Arc<Task>> {
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/// all task will entering this function
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/// this function is mean to executing the task_fn in Task
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fn kernel_task_entry() {
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let current_task = current_task()
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.expect("no current task, it should have current task in kernel task entry");
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current_task.func.call(());
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current_task.exit();
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}
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let result = Task {
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func: self.func.unwrap(),
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data: self.data.unwrap(),
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user_space: self.user_space,
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task_inner: SpinLock::new(TaskInner {
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task_status: TaskStatus::Runnable,
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ctx: TaskContext::default(),
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}),
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exit_code: 0,
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kstack: KernelStack::new_with_guard_page()?,
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link: LinkedListAtomicLink::new(),
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priority: self.priority,
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cpu_affinity: self.cpu_affinity,
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};
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result.task_inner.lock().task_status = TaskStatus::Runnable;
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result.task_inner.lock().ctx.rip = kernel_task_entry as usize;
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// Subtract 8 bytes to reserve space for the return address, otherwise
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// we will write across the page bondary.
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result.task_inner.lock().ctx.regs.rsp =
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(crate::vm::paddr_to_vaddr(result.kstack.end_paddr() - size_of::<u64>())) as u64;
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let arc_self = Arc::new(result);
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arc_self.run();
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Ok(arc_self)
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let task = self.build()?;
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task.run();
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Ok(task)
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}
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}
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