Struct x86_64::instructions::segmentation::CS

pub struct CS;

Code Segment

The segment base and limit are unused in 64-bit mode. Only the L (long), D (default operation size), and DPL (descriptor privilege-level) fields of the descriptor are recognized. So changing the segment register can be used to change privilege level or enable/disable long mode.

Trait Implementations

impl Debug for CS

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

Formats the value using the given formatter.

impl Segment for CS

unsafe fn set_reg(sel: SegmentSelector)

Note this is special since we cannot directly move to CS; x86 requires the instruction pointer and CS to be set at the same time. To do this, we push the new segment selector and return value onto the stack and use a “far return” (retfq) to reload CS and continue at the end of our function.

Note we cannot use a “far call” (lcall) or “far jmp” (ljmp) to do this because then we would only be able to jump to 32-bit instruction pointers. Only Intel implements support for 64-bit far calls/jumps in long-mode, AMD does not.

fn get_reg() -> SegmentSelector

Returns the current value of the segment register.