Struct TaskContext 

#[repr(C)]
pub struct TaskContext {
    pub ra: usize,
    pub sp: usize,
    pub s: [usize; 10],
    pub tp: usize,
    pub pgdl: usize,
    pub fpu: FpuState,
}

Saved hardware states of a task.

The context usually includes:

• Callee-saved registers
• Stack pointer register
• Thread pointer register (for thread-local storage, currently unsupported)
• FP/SIMD registers

On context switch, current task saves its context from CPU to memory, and the next task restores its context from memory to CPU.

Fields

ra: usize

Return Address

sp: usize

Stack Pointer

s: [usize; 10]

loongArch need to save 10 static registers from $r22 to $r31

tp: usize

Thread Pointer

pgdl: usize

Available on crate feature uspace only.

user page table root

fpu: FpuState

Available on crate feature fp-simd only.

Floating Point Unit states

Implementations

impl TaskContext

pub fn new() -> Self

Creates a new default context for a new task.

pub fn init(&mut self, entry: usize, kstack_top: VirtAddr, tls_area: VirtAddr)

Initializes the context for a new task, with the given entry point and kernel stack.

pub fn set_page_table_root(&mut self, pgdl: PhysAddr)

Available on crate feature uspace only.

Changes the page table root in this context.

The hardware register for user page table root (pgdl for loongarch64) will be updated to the next task’s after Self::switch_to.

pub fn switch_to(&mut self, next_ctx: &Self)

Switches to another task.

It first saves the current task’s context from CPU to this place, and then restores the next task’s context from next_ctx to CPU.

Trait Implementations

impl Debug for TaskContext

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for TaskContext

fn default() -> TaskContext

Returns the “default value” for a type.