Multitasking works!

src/bringelle.c

@@ -9,14 +9,26 @@ extern void interrupt_enable();
 
 void utask(){
   char *msg=(char*)4206592+10;
-  msg[0]='T';
+  msg[0]='A';
-  msg[1]='a';
+  msg[1]='\0';
-  msg[2]='s';
+  while(1){
-  msg[3]='k';
-  msg[4]='1';
-  msg[5]='\0';
       asm("mov $0x1, %%eax;int $0x30"::"b"(msg));
-  while(1);
+      for(int i=0;i<10000;i++){
+
+      }
+  }
+}
+
+void utask2(){
+  char *msg=(char*)4206592+10;
+  msg[0]='B';
+  msg[1]='\0';
+  while(1){
+      asm("mov $0x1, %%eax;int $0x30"::"b"(msg));
+      for(int i=0;i<10000;i++){
+        
+      }
+  }
 }
 
 void bringelle(){
@@ -34,10 +46,15 @@ void bringelle(){
   show_tics=1;
 
   // Utask
-  print("Launch user task \n");
+  print("Launch user tasks \n");
-  int* page_dir=paging_allocate(2);
-  run_task(page_dir, utask,100);
 
+  int* page_dir=paging_allocate(2);
+  task_create(page_dir, utask,100);
+
+  int* page_dir2=paging_allocate(2);
+  task_create(page_dir2, utask2,100);
+
+  scheduler_start();
 
   while(1);
 }

src/core/idt.c

@@ -25,7 +25,7 @@ void idt_init(){
         if(i==33)
             idt_write_entry((IDT_ENTRY){0x08,(u32)&INT_KEYPRESS,IDT_INT_GATE},i);
         if(i==48)
-            idt_write_entry((IDT_ENTRY){0x08,(u32)&INT_SYSCALL,IDT_TRAP_GATE},i);
+            idt_write_entry((IDT_ENTRY){0x08,(u32)&INT_SYSCALL,IDT_INT_GATE|0x6000},i);
     }
     // Load IDT
     asm("lidtl (IDTR)");

src/core/paging.h

@@ -9,7 +9,13 @@
 #else
     #define PAGING_MAX_DIR_ENTRY PAGING_MAX_PAGES/1024
 #endif
-#define PADDR(entry) (((u32)entry)&0xFFFFF000)
+#define PAGING_PADDR(entry) ((int*)(((u32)entry)&0xFFFFF000))
+#define PAGING_ENTRY_POINT_VIRT (1024*PAGING_PAGE_SIZE+3*PAGING_PAGE_SIZE)
+#define PAGING_ENTRY_POINT_PHY(page_dir) ((int*)(((int*)((((int*)page_dir)[1])&0xFFFFF000))[3]&0xFFFFF000))
+
+
+
+
 
 /**
  * Configure and enable paging

src/core/scheduler.c

@@ -9,15 +9,13 @@ PROC procs[MAX_PROC];
 u16 current_id;
 u16 nproc;
 
-void schedule(){
+void schedule(u32 *stack){
   // Note that this function is called by clock
   // clock is called by INT_CLOCK (core/int.S)
   // which store all the process information on
   // the stack. Thus, knowing the C calling conventions
   // and that schedule() is call by two functions with no parameters,
   // the first process register can be accessed by ebp+2
-  u32 *stack;
-  asm("mov %%ebp, %0":"=r" (stack));
 
   // No proc to schedule
   if(nproc<2)
@@ -47,6 +45,7 @@ void schedule(){
   current_id++;
   if(current_id>=nproc)
     current_id=0;
+  p=&procs[current_id];
  
   // Have a clean stack on next interrupt
   TSS.esp0=(u32)stack+19;
@@ -58,13 +57,16 @@ void schedule(){
 
   // Perform task switch
   asm(
-    "mov %0, %%esi    \n\t"
+    "push %0          \n\t"
     "jmp task_switch  \n\t"
     :: "a" (p)
   );
 }
 
 void clock(){
+  u32* stack;
+  asm("mov %%ebp, %0":"=r" (stack));
+
   static int tic=0;
   static int sec=0;
   tic++;
@@ -75,46 +77,69 @@ void clock(){
       putchar('.');
   }
   if(scheduler_on==1)
-    schedule();
+    schedule(stack);
 }
 
-void run_task(int *page_dir, void *task, int task_size){
+void task_create(int *page_dir, void *task, int task_size){
+  if(nproc<=MAX_PROC){
     // Compute various addresses
-    int*pt_addr=(int*)PADDR(page_dir[1]);
+    void *entry_point=PAGING_ENTRY_POINT_VIRT;
-    void *entry_point=(void*)(PADDR(pt_addr[3]));
+    void *ustack=(void*)(PAGING_ENTRY_POINT_VIRT+0xFF);
-    void *ustack=(void*)((int)entry_point+0xFF);
 
     // Load the task into memory
-    memcpy(task,entry_point, task_size);
+    memcpy(task,PAGING_ENTRY_POINT_PHY(page_dir), task_size);
 
-    // Load page directory
+    // Setup process registers
+    PROC *p=&procs[nproc];
+    p->regs.cs=0x23; // Task cs which is 0x30 along with prlv which is 0x3
+    p->regs.eip=entry_point;
+    p->regs.ss=0x33; // Task ss which is 0x20 along with prlv which is 0x3
+    p->regs.esp=ustack; // Stack is here for now...
+    p->regs.ds=0x2B; // GDT entry 0x28 along with prlv which is 0x3
+    p->regs.eax=0;
+    p->regs.ebx=0;
+    p->regs.ecx=0;
+    p->regs.edx=0;
+
+    // Manage eflags
+    u32 eflags;
     asm (
-      "mov %0, %%eax           \n\t"
-      "mov %%eax,%%cr3         \n\t"
-    :: "b"(page_dir)
-    );
-
-     // Setup users adresses
- 
-    // Switch to user task
-    asm (
-    "cli                      \n\t" // Ensure we do not get interrupted
-    "movl %%ss, %%eax         \n\t"
-    "movl %%eax, %0           \n\t" // Save kernel ss segment into the TSS
-    "movl %%esp, %1           \n\t" // Save kernel esp into the TSS BEFORE setting up the stack
-    "pushl $0x33              \n\t" // Push task ss which is 0x30 along with prlv which is 0x3
-    "pushl %2                 \n\t" // Push task esp
     "pushfl                   \n\t" // Retrieve flags
     "popl %%eax               \n\t"
     "orl $0x200, %%eax        \n\t" // Enable interrupt for the user task
     "and $0xffffbfff, %%eax   \n\t" // Clear the NT flags
-    "push %%eax               \n\t" // Push task flags
+    "mov %%eax, %0            \n\t" // Get flags into eflag
-    "push $0x23               \n\t" // Push task cs which is 0x20 along with prlv which is 0x3
+    : "=m" (eflags)
-    "push %3                  \n\t" // Push task entry point
+    );
-    "mov $0x2B, %%eax         \n\t" // GDT entry 0x28 along with prlv which is 0x3
+    p->regs.eflags=eflags;
-    "mov %%eax, %%ds          \n\t" // Setting up user data segment
+
-    "iret                     \n\t" // Launch user task
+    // Setup other attributes
-    : "=m" (TSS.ss0), "=m" (TSS.esp0)
+    p->id=nproc;
-    : "b" (ustack), "c" (entry_point)
+    p->pid=nproc;
+    p->page_dir=page_dir;
+    nproc++;
+  }
+}
+
+void scheduler_start(){
+  if(nproc>0){
+    asm("cli");
+    scheduler_on=1; // Enable scheduling
+    u32 *stack;
+    asm("mov %%ebp, %0":"=r" (stack));
+    TSS.esp0=(u32)stack+1; // Remove ebp (c call convention)
+    asm("mov %%ss, %0": "=m" (TSS.ss0));
+
+    current_id=1;
+    PROC *p=&procs[current_id];
+
+    // Ensure interrupts are activated and NT flag is clear
+    p->regs.eflags|=0x200;
+    p->regs.eflags&=0xffffbfff;
+    asm(
+      "push %0    \n\t"
+      "jmp task_switch"
+      :: "a" (p)
       );
   }
+}

src/core/scheduler.h

@@ -34,6 +34,6 @@ extern u16 nproc;
 
 void clock();
 void schedule();
-void run_task(int *page_dir, void *task, int task_size);
+void task_create(int *page_dir, void *task, int task_size);
-
+void scheduler_start();
 #endif

src/core/scheduler_asm.S

@@ -4,24 +4,24 @@
 // to a PROC structure and jump
 // to this process
 task_switch:
-    push 12(%esi)  # eax (cf PROC struct)
+    pop %esi
-    push 16(%esi)  # ebx
+    push 8(%esi)  # eax (cf PROC struct)
-    push 20(%esi)  # ecx
+    push 12(%esi)  # ebx
-    push 24(%esi)  # edx
+    push 16(%esi)  # ecx
-    push 44(%esi)  # ebp
+    push 20(%esi)  # edx
-    push 48(%esi)  # esi
+    push 40(%esi)  # ebp
-    push 52(%esi)  # edi
+    push 48(%esi)  # edi
-    push 56(%esi)  # ds
+    push 52(%esi)  # ds
-    push 60(%esi)  # es
+    push 56(%esi)  # es
-    push 64(%esi)  # fs
+    push 60(%esi)  # fs
-    push 68(%esi)  # gs
+    push 64(%esi)  # gs
 
     // Don't forget to clear the interrupt
     movb $0x20, %al
     outb %al, $0x20
 
     // Setup process page directory
-    mov 8(%esi), %eax
+    mov 4(%esi), %eax
     mov %eax, %cr3
 
     // Setup registers
@@ -30,7 +30,6 @@ task_switch:
     pop %es
     pop %ds
     pop %edi
-    pop %esi
     pop %ebp
     pop %edx
     pop %ecx
@@ -38,9 +37,11 @@ task_switch:
     pop %eax
 
     // Perform the task switch
-    push 36(%esi)  # ss
+    push 32(%esi)  # ss
-    push 40(%esi)  # esp
+    push 36(%esi)  # esp
-    push 72(%esi)  # eflags
+    push 68(%esi)  # eflags
-    push 28(%esi)  # cs
+    push 24(%esi)  # cs
-    push 32(%esi)  # eip
+    push 28(%esi)  # eip
-    iret
+    mov 52(%esi), %ds # Choose the right data segment
+    mov 44(%esi), %esi # Now restore task esi
+    iret # Launch task