Struct UspaceContext

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pub struct UspaceContext(/* private fields */);

Available on crate feature uspace only.

Expand description

Context to enter user space.

Implementations§

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impl UspaceContext

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pub const fn empty() -> Self

Creates an empty context with all registers set to zero.

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pub fn new(entry: usize, ustack_top: VirtAddr, arg0: usize) -> Self

Creates a new context with the given entry point, user stack pointer, and the argument.

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pub const fn from(tf: &TrapFrame) -> Self

Creates a new context from the given TrapFrame.

It copies almost all registers except CS and SS which need to be set to the user segment selectors.

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pub unsafe fn enter_uspace(&self, kstack_top: VirtAddr) -> !

Enters user space.

It restores the user registers and jumps to the user entry point (saved in rip). When an exception or syscall occurs, the kernel stack pointer is switched to kstack_top.

§Safety

This function is unsafe because it changes processor mode and the stack.

Methods from Deref<Target = TrapFrame>§

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pub fn arg0(&self) -> usize

Gets the 0th syscall argument.

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pub fn set_arg0(&mut self, rdi: usize)

Sets the 0th syscall argument.

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pub fn arg1(&self) -> usize

Gets the 1st syscall argument.

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pub fn set_arg1(&mut self, rsi: usize)

Sets the 1st syscall argument.

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pub fn arg2(&self) -> usize

Gets the 2nd syscall argument.

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pub fn set_arg2(&mut self, rdx: usize)

Sets the 2nd syscall argument.

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pub fn arg3(&self) -> usize

Gets the 3rd syscall argument.

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pub fn set_arg3(&mut self, r10: usize)

Sets the 3rd syscall argument.

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pub fn arg4(&self) -> usize

Gets the 4th syscall argument.

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pub fn set_arg4(&mut self, r8: usize)

Sets the 4th syscall argument.

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pub fn arg5(&self) -> usize

Gets the 5th syscall argument.

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pub fn set_arg5(&mut self, r9: usize)

Sets the 5th syscall argument.

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pub fn is_user(&self) -> bool

Whether the trap is from userspace.

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pub fn ip(&self) -> usize

Gets the instruction pointer.

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pub fn set_ip(&mut self, rip: usize)

Sets the instruction pointer.

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pub fn sp(&self) -> usize

Gets the stack pointer.

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pub fn set_sp(&mut self, rsp: usize)

Sets the stack pointer.

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pub fn retval(&self) -> usize

Gets the return value register.

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pub fn set_retval(&mut self, rax: usize)

Sets the return value register.

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pub fn push_ra(&mut self, addr: usize)

Push the return address.

On x86_64, return address is stored in stack, so we need to modify the stack in order to change the return address. This function uses a separate name (rather than set_ra) to avoid confusion and misuse.

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