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Simple, unsafe context switch

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This commit is contained in:
Jeremy Soller 2016-08-28 18:38:53 -06:00
parent 6715d5c534
commit 6e3f59ba8e
5 changed files with 53 additions and 7 deletions
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22
arch/x86_64/src/context.rs
View file

@ -1,3 +1,12 @@
use core::mem;
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(Debug)]
pub struct Context {
/// RFLAGS register
@ -35,6 +44,11 @@ impl Context {
}
}
pub fn set_stack(&mut self, address: usize) {
self.rsp = address;
}
/// Switch to the next context by restoring its stack and registers
#[inline(never)]
#[naked]
pub unsafe fn switch_to(&mut self, next: &mut Context) {
@ -68,15 +82,17 @@ impl Context {
asm!("mov $0, r15" : "=r"(self.r15) : : "memory" : "intel", "volatile");
asm!("mov r15, $0" : : "r"(next.r15) : "memory" : "intel", "volatile");
asm!("mov $0, rbp" : "=r"(self.rbp) : : "memory" : "intel", "volatile");
asm!("mov rbp, $0" : : "r"(next.rbp) : "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");
/* TODO
asm!("mov $0, cr3" : "=r"(self.cr3) : : "memory" : "intel", "volatile");
asm!("mov cr3, $0" : : "r"(self.cr3) : "memory" : "intel", "volatile");
*/
//CONTEXT_SWITCH_LOCK.store(false, Ordering::SeqCst);
}
}

4
arch/x86_64/src/start.rs
View file

@ -92,7 +92,7 @@ pub unsafe extern fn kstart() -> ! {
}
// Initialize display
display::init(&mut active_table);
//display::init(&mut active_table);
// Reset AP variables
AP_COUNT.store(0, Ordering::SeqCst);
@ -100,7 +100,7 @@ pub unsafe extern fn kstart() -> ! {
HEAP_FRAME.store(0, Ordering::SeqCst);
// Read ACPI tables, starts APs
acpi::init(&mut active_table);
//acpi::init(&mut active_table);
// Map heap
{