107 lines
3.5 KiB
Rust
107 lines
3.5 KiB
Rust
use core::sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering};
|
|
|
|
/// This must be used by the kernel to ensure that context switches are done atomically
|
|
/// Compare and exchange this to true when beginning a context switch on any CPU
|
|
/// The Context::switch_to function will set it back to false, allowing other CPU's to switch
|
|
/// This must be done, as no locks can be held on the stack during switch
|
|
pub static CONTEXT_SWITCH_LOCK: AtomicBool = ATOMIC_BOOL_INIT;
|
|
|
|
#[derive(Clone, Debug)]
|
|
pub struct Context {
|
|
/// Page table pointer
|
|
cr3: usize,
|
|
/// RFLAGS register
|
|
rflags: usize,
|
|
/// RBX register
|
|
rbx: usize,
|
|
/// R12 register
|
|
r12: usize,
|
|
/// R13 register
|
|
r13: usize,
|
|
/// R14 register
|
|
r14: usize,
|
|
/// R15 register
|
|
r15: usize,
|
|
/// Base pointer
|
|
rbp: usize,
|
|
/// Stack pointer
|
|
rsp: usize
|
|
}
|
|
|
|
impl Context {
|
|
pub fn new() -> Context {
|
|
Context {
|
|
cr3: 0,
|
|
rflags: 0,
|
|
rbx: 0,
|
|
r12: 0,
|
|
r13: 0,
|
|
r14: 0,
|
|
r15: 0,
|
|
rbp: 0,
|
|
rsp: 0
|
|
}
|
|
}
|
|
|
|
pub fn set_page_table(&mut self, address: usize) {
|
|
self.cr3 = address;
|
|
}
|
|
|
|
pub fn set_stack(&mut self, address: usize) {
|
|
self.rsp = address;
|
|
}
|
|
|
|
/// Switch to the next context by restoring its stack and registers
|
|
#[cold]
|
|
#[inline(never)]
|
|
#[naked]
|
|
pub unsafe fn switch_to(&mut self, next: &mut Context) {
|
|
/*
|
|
asm!("fxsave [$0]" : : "r"(self.fx) : "memory" : "intel", "volatile");
|
|
self.loadable = true;
|
|
if next.loadable {
|
|
asm!("fxrstor [$0]" : : "r"(next.fx) : "memory" : "intel", "volatile");
|
|
}else{
|
|
asm!("fninit" : : : "memory" : "intel", "volatile");
|
|
}
|
|
*/
|
|
|
|
asm!("mov $0, cr3" : "=r"(self.cr3) : : "memory" : "intel", "volatile");
|
|
if next.cr3 != self.cr3 {
|
|
asm!("mov cr3, $0" : : "r"(next.cr3) : "memory" : "intel", "volatile");
|
|
}
|
|
|
|
asm!("pushfq ; pop $0" : "=r"(self.rflags) : : "memory" : "intel", "volatile");
|
|
asm!("push $0 ; popfq" : : "r"(next.rflags) : "memory" : "intel", "volatile");
|
|
|
|
asm!("mov $0, rbx" : "=r"(self.rbx) : : "memory" : "intel", "volatile");
|
|
asm!("mov rbx, $0" : : "r"(next.rbx) : "memory" : "intel", "volatile");
|
|
|
|
asm!("mov $0, r12" : "=r"(self.r12) : : "memory" : "intel", "volatile");
|
|
asm!("mov r12, $0" : : "r"(next.r12) : "memory" : "intel", "volatile");
|
|
|
|
asm!("mov $0, r13" : "=r"(self.r13) : : "memory" : "intel", "volatile");
|
|
asm!("mov r13, $0" : : "r"(next.r13) : "memory" : "intel", "volatile");
|
|
|
|
asm!("mov $0, r14" : "=r"(self.r14) : : "memory" : "intel", "volatile");
|
|
asm!("mov r14, $0" : : "r"(next.r14) : "memory" : "intel", "volatile");
|
|
|
|
asm!("mov $0, r15" : "=r"(self.r15) : : "memory" : "intel", "volatile");
|
|
asm!("mov r15, $0" : : "r"(next.r15) : "memory" : "intel", "volatile");
|
|
|
|
asm!("mov $0, rsp" : "=r"(self.rsp) : : "memory" : "intel", "volatile");
|
|
asm!("mov rsp, $0" : : "r"(next.rsp) : "memory" : "intel", "volatile");
|
|
|
|
asm!("mov $0, rbp" : "=r"(self.rbp) : : "memory" : "intel", "volatile");
|
|
asm!("mov rbp, $0" : : "r"(next.rbp) : "memory" : "intel", "volatile");
|
|
|
|
asm!("call context_switch_unlock" : : : "memory" : "intel", "volatile");
|
|
}
|
|
}
|
|
|
|
/// Unset global lock, set inside of kernel
|
|
#[no_mangle]
|
|
extern fn context_switch_unlock(){
|
|
CONTEXT_SWITCH_LOCK.store(false, Ordering::SeqCst);
|
|
}
|