Debug GDT enable multitasking

1 files changed, 79 insertions, 12 deletions

diff --git a/src/core/scheduler.cc b/src/core/scheduler.cc
index 00741fe..fee5716 100644
--- a/src/core/scheduler.cc
+++ b/src/core/scheduler.cc
@@ -1,40 +1,107 @@
 #include "scheduler.hpp"
+#include "boucane.hpp"
+#include "core/apic.hpp"
 
-TASK tasks[MAX_TASK];
-u32 ntasks=0;
+PROC procs[MAX_TASK];
+u32 nproc=0;
 char show_ticks=0;
+char scheduling=0;
+u32 active_process=0;
 
 extern "C" void clock(){
     if(show_ticks)
         print(".");
+    if(scheduling)
+        schedule();
 }
 void schedule(){
+    // First get a pointer to the first process saved register.
+    // Since this is called by clock(), %rbp contains a pointer
+    // to the clock() %rbp value and then we access to the registers SAVE_REGS in int.S
+    u64* stack;
+    asm("mov %%rbp, %%rax;mov (%%rax), %%rbx; add $16, %%rbx; mov %%rbx,%0": "=m"(stack)::"rax","rbx");
+    
+    // Save current task
+    PROC *t=&procs[active_process];
+    t->registers.r8=stack[0];
+    t->registers.r9=stack[1];
+    t->registers.r10=stack[2];
+    t->registers.r11=stack[3];
+    t->registers.r12=stack[4];
+    t->registers.r13=stack[5];
+    t->registers.r14=stack[6];
+    t->registers.r15=stack[7];
+    t->registers.rdi=stack[8];
+    t->registers.rsi=stack[9];
+    t->registers.rbp=stack[10];
+    t->registers.rdx=stack[11];
+    t->registers.rcx=stack[12];
+    t->registers.rbx=stack[13];
+    t->registers.rax=stack[14];
+    t->registers.rip=stack[15];
+    t->registers.cs=stack[16];
+    t->registers.eflags=stack[17];
+    t->registers.rsp=stack[18];
+    t->registers.ds=stack[19];
 
+    // Goto next task
+    active_process++;
+    if(active_process>=nproc)
+        active_process=0;
+
+    t=&procs[active_process];
+    kvar_tss.rsp0=t->registers.rsp0;
+
+    // Clock acknownledgement
+    apic_ack();
+    
+    asm volatile(
+        "mov %0, %%rdi       \n\t"  
+        "jmp switch          \n\t"
+        :: "a" (t)
+    );
 }
 
 
 void create_task(void* task, u32 size){
-    if(ntasks>=MAX_TASK){
+    if(nproc>=MAX_TASK){
         printk("Could not create more tasks.");
         return;
     }
 
-    TASK *t=&tasks[ntasks];
-    t->id=ntasks;
-    t->pid=ntasks;
+    PROC *t=&procs[nproc];
+    t->id=nproc;
+    t->pid=nproc;
     t->size=size;
-    t->pml4=paging_create_task(size/4096+1);
+
+    u32 npages=size%4096 ? size/4096 + 1 : size/4096;
+    // Note that paging_create_task() allocate 2 more pages (one for the user stack and
+    // the other for the kernel stack)
+    t->pml4=paging_create_task(npages);
+    t->registers.rsp=TASK_VMA+npages*4096+4096;   // User stack
+    t->registers.rsp0=TASK_VMA+npages*4096+4096*2;  // Kernel stack on the last page
+
+    t->registers.rip=TASK_VMA;
+    t->registers.cs=0x1B; // 0x18 and 0x3 privilege
+    t->registers.ds=0x23; // 0x20 and 0x3 privilege
 
     // Load task using
     lpml4(t->pml4);
     memcpy(task, TASK_VMA, size);
     lpml4(kpml4);
-
-    ntasks++;
+    
+    nproc++;
 }
 
 void scheduler_start(){
-    TASK *t=&tasks[0];
-    lpml4(t->pml4);
-    asm("jmp switch");
+    scheduling=1;
+    active_process=0;
+    PROC *t=&procs[active_process];
+    kvar_tss.rsp0=t->registers.rsp0;
+    asm(
+        "cli             \n\t"
+        "mov %0, %%rdi   \n\t"    
+        "jmp switch      \n\t"
+        :: "r" (t)
+    );
 }
\ No newline at end of file