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pub struct Msr(u32);
impl Msr {
pub unsafe fn read(&self) -> u64 {
let (high, low): (u32, u32);
asm!("rdmsr" : "={eax}" (low), "={edx}" (high) : "{ecx}" (self.0) : "memory" : "volatile");
((high as u64) << 32) | (low as u64)
}
pub unsafe fn write(&mut self, value: u64) {
let low = value as u32;
let high = (value >> 32) as u32;
asm!("wrmsr" :: "{ecx}" (self.0), "{eax}" (low), "{edx}" (high) : "memory" : "volatile" );
}
}
pub struct Efer;
impl Efer {
pub const MSR: Msr = Msr(0xC0000080);
pub fn read() -> EferFlags {
EferFlags::from_bits_truncate(unsafe { Self::MSR.read() })
}
pub unsafe fn write(flags: EferFlags) {
let mut value = Self::MSR.read();
value |= flags.bits();
Self::MSR.write(value);
}
pub unsafe fn update<F>(f: F) where F: FnOnce(&mut EferFlags) {
let mut flags = Self::read();
f(&mut flags);
Self::write(flags);
}
}
bitflags! {
pub struct EferFlags: u64 {
const SYSTEM_CALL_EXTENSIONS = 1 << 0;
const LONG_MODE_ENABLE = 1 << 8;
const LONG_MODE_ACTIVE = 1 << 10;
const NO_EXECUTE_ENABLE = 1 << 11;
const SECURE_VIRTUAL_MACHINE_ENABLE = 1 << 12;
const LONG_MODE_SEGMENT_LIMIT_ENABLE = 1 << 13;
const FAST_FXSAVE_FXRSTOR = 1 << 14;
const TRANSLATION_CACHE_EXTENSION = 1 << 15;
}
}