More syscall preparation

kernel/src/cpu/cpu.rs

@@ -6,8 +6,9 @@ use raw_cpuid::CpuId;
 use crate::{
     cpu::{gdt::setup_gdt, idt::setup_idt},
     sys::{
-        lapic::{setup_lapic, setup_lapic_timer},
+        lapic::{get_current_lapic_id, setup_lapic, setup_lapic_timer},
         scheduler::yield_task,
+        task::{CPUData, CPUDATA},
     },
 };
 
@@ -51,6 +52,10 @@ pub fn set_cpu_flags() {
         // Clear IF and DF
         asm!("wrmsr", in("rcx") 0xc0000084_u64, in("rax") 1 << 9 | 1 << 10, in("rdx") 0);
     }
+    let cpudata_address = &CPUDATA.lock()[get_current_lapic_id()] as *const CPUData as u64;
+    unsafe {
+        asm!("wrmsr", in("rcx") 0xc0000102_u64, in("rax") cpudata_address, in("rdx") cpudata_address >> 32);
+    }
 }
 pub fn enable_user_memory_access() {
     unsafe {

kernel/src/cpu/gdt.rs

@@ -59,6 +59,7 @@ pub fn setup_gdt() {
     tss.ist[0] = allocate_stack();
     tss.ist[1] = allocate_stack();
     tss.ist[2] = allocate_stack();
+    tss.ist[3] = allocate_stack();
     let gdt = Box::leak(Box::new(GDT {
         entries: [
             GDTEntry {

kernel/src/cpu/idt.rs

@@ -2,6 +2,8 @@ use core::{arch::asm, mem::size_of};
 
 use alloc::boxed::Box;
 
+use super::isr::ISR_SCHEDULER;
+
 #[repr(C)]
 #[derive(Clone, Copy)]
 struct IDTEntry {
@@ -326,4 +328,5 @@ pub fn setup_idt() {
     idt.entries[2].ist = 1; // NMI
     idt.entries[8].ist = 2; // Double fault
     idt.entries[18].ist = 3; // Machine Check
+    idt.entries[ISR_SCHEDULER as usize].ist = 4;
 }

kernel/src/cpu/isr.rs

@@ -12,7 +12,7 @@ use crate::{
         locks::Spinlock,
         scheduler::scheduler,
         sync::{IN_ISR_HANDLER, LOCKS_HELD},
-        task::{terminate_current_task, terminate_tasks},
+        task::terminate_current_task,
     },
     BROADCASTED_PANIC,
 };
@@ -114,12 +114,14 @@ extern "C" fn isr_handler(state: &mut ISRState) {
         if state.cs == 0x23 && state.isr != 2 && state.isr != 8 && state.isr != 18 {
             warn!("Exception in usermode: {}", EXCEPTIONS[state.isr as usize]);
             terminate_current_task();
-            state.isr = ISR_SCHEDULER;
+            IN_ISR_HANDLER[lapic_id].store(false, Ordering::SeqCst);
+            unsafe {
+                asm!("int $254");
+            }
+            panic!("Failed to terminate task");
         } else {
             panic!("Exception: {}", EXCEPTIONS[state.isr as usize]);
         }
-    } else {
-        terminate_tasks();
     }
     if state.isr == ISR_SCHEDULER {
         scheduler(state);

kernel/src/cpu/syscall.s

@@ -2,4 +2,8 @@
 
 .global syscall
 syscall:
+  swapgs
+  mov %rsp, %gs:8
+  mov %gs:0, %rsp
+  swapgs
   jmp .

kernel/src/sys/task.rs

@@ -34,7 +34,7 @@ pub struct Task {
     pub id: usize,
     pub process: Arc<Spinlock<Process>>,
     state: ISRState,
-    _kernel_stack: Vec<u8>,
+    kernel_stack: Vec<u8>,
     initial_func: fn(),
     pub task_state: TaskState,
     pub sleep_until_us: usize,
@@ -42,6 +42,12 @@ pub struct Task {
     pub semaphore_requested_count: usize,
 }
 
+#[repr(C)]
+pub struct CPUData {
+    pub kernel_stack: u64,
+    pub user_stack: u64,
+}
+
 pub const STACK_SIZE: usize = 64 * 1024;
 static NEXT_TASK_ID: AtomicUsize = AtomicUsize::new(2);
 pub static CURRENT_TASKS: Spinlock<[Option<Task>; 256]> = Spinlock::new([const { None }; 256]);
@@ -49,7 +55,7 @@ static RFLAGS: AtomicU64 = AtomicU64::new(0);
 pub static MULTITASKING_ENABLED: AtomicBool = AtomicBool::new(false);
 pub static STARTING_AP_ID: AtomicI64 = AtomicI64::new(-1);
 pub static ALL_APS_STARTED: AtomicBool = AtomicBool::new(false);
-pub static TERMINATE_STASKS: [Spinlock<Vec<Task>>; 256] = [const { Spinlock::new(Vec::new()) }; 256];
+pub static CPUDATA: Spinlock<[CPUData; 256]> = Spinlock::new([const { CPUData { kernel_stack: 0, user_stack: 0 } }; 256]);
 
 pub fn allocate_stack() -> u64 {
     let stack: Vec<u8> = vec![0; STACK_SIZE];
@@ -60,14 +66,17 @@ pub fn switch_task(current_state: &mut ISRState, new_task: Task) {
     let mut current_tasks = CURRENT_TASKS.lock();
     if let Some(mut current_task) = current_tasks[lapic_id].take() {
         current_task.state = *current_state;
+        if current_task.task_state == TaskState::Terminated {
+            unsafe {
+                get_kernel_process().lock().address_space.switch();
+            }
+        }
         match current_task.task_state {
             TaskState::Ready => {
                 SCHEDULER.lock().add_task(current_task);
             }
             TaskState::Idle => IDLE_TASKS.lock().push(current_task),
-            TaskState::Terminated => {
-                TERMINATE_STASKS[lapic_id].lock().push(current_task);
-            }
+            TaskState::Terminated => {}
             TaskState::Sleeping => sleep_internal(current_task),
             TaskState::SemaphoreBlocked => lock_semaphore_internal(current_task),
         }
@@ -80,6 +89,8 @@ pub fn switch_task(current_state: &mut ISRState, new_task: Task) {
             process.address_space.switch();
         }
     }
+    let kernel_stack = new_task.kernel_stack.as_ptr() as u64 + STACK_SIZE as u64;
+    CPUDATA.lock()[lapic_id].kernel_stack = kernel_stack;
     current_tasks[get_current_lapic_id()] = Some(new_task);
     schedule_timer_interrupt();
 }
@@ -112,7 +123,7 @@ pub fn create_task(process: Arc<Spinlock<Process>>, func: fn()) -> Task {
             rsp: stack.as_ptr() as u64 + STACK_SIZE as u64,
             ss: 16,
         },
-        _kernel_stack: stack,
+        kernel_stack: stack,
         initial_func: func,
         task_state: TaskState::Ready,
         sleep_until_us: 0,
@@ -138,9 +149,7 @@ extern "C" fn task_entry() -> ! {
         func = task[get_current_lapic_id()].as_ref().unwrap().initial_func;
     }
     func();
-    {
-        terminate_current_task();
-    }
+    terminate_current_task();
     yield_task();
     panic!("Failed to terminate task");
 }
@@ -159,9 +168,6 @@ fn idle_main() {
         hlt();
     }
 }
-pub fn terminate_tasks() {
-    TERMINATE_STASKS[get_current_lapic_id()].lock().clear();
-}
 pub fn setup_multitasking() -> ! {
     let rflags = get_rflags();
     RFLAGS.store(rflags, core::sync::atomic::Ordering::SeqCst);