Struct SwapGsGuard 

struct SwapGsGuard {
    from_ring3: bool,
}

RAII guard: swap GS to kernel on entry if we came from Ring 3, and restore user GS automatically on drop (covers every exit path including early returns).

Why this is needed

After swapgs ; iretq in the Ring-3 trampoline:

• IA32_GS_BASE = 0 (user GS base, inactive)
• IA32_KERNEL_GS_BASE = kernel per-CPU pointer When an interrupt fires from Ring 3, the CPU does NOT automatically call swapgs. The first gs:[0] access (e.g. in current_cpu_index) would dereference virtual address 0 → page fault → double fault → triple fault.

Safety

Must be constructed before any gs:[…] access in the handler. InterruptStackFrame::code_segment is a plain memory read from the interrupt stack : it does not access GS.

Fields

from_ring3: bool

Implementations

impl SwapGsGuard

fn new(from_ring3: bool) -> Self

Construct. If from_ring3 is true, executes swapgs immediately to restore the kernel per-CPU GS base.

Trait Implementations

impl Drop for SwapGsGuard

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.