diff options
| -rw-r--r-- | src/core/idt.c | 2 | ||||
| -rw-r--r-- | src/core/scheduler.c | 35 | ||||
| -rw-r--r-- | src/core/scheduler.h | 1 | ||||
| -rw-r--r-- | src/core/scheduler_asm.S | 28 |
4 files changed, 49 insertions, 17 deletions
diff --git a/src/core/idt.c b/src/core/idt.c index 861927a..30bb113 100644 --- a/src/core/idt.c +++ b/src/core/idt.c @@ -26,7 +26,7 @@ void idt_init(){ if(i==33) idt_write_entry((IDT_ENTRY){0x08,(u32)&INT_KEYPRESS,IDT_INT_GATE|IDT_P},i); if(i==48) - idt_write_entry((IDT_ENTRY){0x08,(u32)&INT_SYSCALL,IDT_INT_GATE|IDT_P|IDT_PRVL_3},i); + idt_write_entry((IDT_ENTRY){0x08,(u32)&INT_SYSCALL,IDT_TRAP_GATE|IDT_P|IDT_PRVL_3},i); } // Load IDT asm("lidtl (IDTR)"); diff --git a/src/core/scheduler.c b/src/core/scheduler.c index 59f3b9d..0c1d255 100644 --- a/src/core/scheduler.c +++ b/src/core/scheduler.c @@ -37,8 +37,19 @@ void schedule(u32 *stack){ p->regs.eip=stack[12]; p->regs.cs=stack[13]; p->regs.eflags=stack[14]; - p->regs.esp=stack[15]; - p->regs.ss=stack[16]; + + // If clock occurs during a syscall (another interrupt) + if(p->regs.cs==0x08){ + // Since we where already in kernel mode + // the CPU did not push ss and esp + // thus esp point to + p->regs.esp=&stack[15]; // Since we came from another interrupt this value will be restore by the last interrupt + p->regs.ss=TSS.ss0; + } + else { + p->regs.esp=stack[15]; + p->regs.ss=stack[16]; + } // Get the next task to run current_id++; @@ -46,9 +57,9 @@ void schedule(u32 *stack){ current_id=0; p=&procs[current_id]; - // Have a clean stack on next interrupt - TSS.esp0=(u32)stack+17; - asm("mov %%ss, %0": "=m" (TSS.ss0)); + // Use kernel stack of the next task + TSS.ss0=p->regs.ss0; + TSS.esp0=p->regs.esp0; // Ensure interrupts are activated and NT flag is clear p->regs.eflags|=0x200; @@ -90,6 +101,8 @@ void task_create(void *task, int task_size){ void *entry_point=PAGING_ENTRY_POINT_VIRT; // User stack start at the end of last allocated page (since addresses are going down) void *ustack=(void*)(PAGING_ENTRY_POINT_VIRT+allocated*4096); + // Kernel stack start at the end of last allocated page +1 (see paging_allocate() implementation) + void *kstack=(void*)(PAGING_ENTRY_POINT_VIRT+(allocated+1)*4096); // Load the task into memory memcpy(task,PAGING_ENTRY_POINT_PHY(page_dir), task_size); @@ -105,6 +118,8 @@ void task_create(void *task, int task_size){ p->regs.ebx=0; p->regs.ecx=0; p->regs.edx=0; + p->regs.ss0=0x18; + p->regs.esp0=kstack; // Manage eflags u32 eflags; @@ -135,19 +150,15 @@ void scheduler_start(){ // Enable scheduling scheduler_on=1; - // Save kernel stack state - u32 *stack; - asm("mov %%ebp, %0":"=r" (stack)); - // Remove ebp from the (c call convention) and return address (call) - TSS.esp0=(u32)stack+2; - asm("mov %%ss, %0": "=m" (TSS.ss0)); - // Get first stack current_id=0; PROC *p=&procs[current_id]; // Ensure interrupts are activated and NT flag is clear p->regs.eflags|=0x200; p->regs.eflags&=0xffffbfff; + // Use task kernel stack + TSS.ss0=p->regs.ss0; + TSS.esp0=p->regs.esp0; // Switch to user task asm( "push %0 \n\t" diff --git a/src/core/scheduler.h b/src/core/scheduler.h index 3410ba1..9678470 100644 --- a/src/core/scheduler.h +++ b/src/core/scheduler.h @@ -14,6 +14,7 @@ typedef struct REGISTERS { u32 esi, edi; u32 ds, es, fs, gs; u32 eflags; + u32 ss0, esp0; } __attribute__((packed)) REGISTERS; // If you change the following struct diff --git a/src/core/scheduler_asm.S b/src/core/scheduler_asm.S index 1f916ec..2fdf3e5 100644 --- a/src/core/scheduler_asm.S +++ b/src/core/scheduler_asm.S @@ -5,6 +5,24 @@ // to this process task_switch: pop %esi + + // Switch to the new task kernel stack + mov 72(%esi), %ss + mov 76(%esi), %esp + + // If we where in kernel mode we should keep using the same + // stack which is stored in regs.ss and regs.esp by schedule + mov 24(%esi), %eax + cmp $0x08, %eax # Check if we were in kernel mode + jne skip_kernel_stack + mov 32(%esi), %ss + mov 36(%esi), %esp + skip_kernel_stack: + + // Setup process page directory to be able to use task stack + mov 4(%esi), %eax + mov %eax, %cr3 + push 8(%esi) # eax (cf PROC struct) push 12(%esi) # ebx push 16(%esi) # ecx @@ -20,10 +38,6 @@ task_switch: movb $0x20, %al outb %al, $0x20 - // Setup process page directory - mov 4(%esi), %eax - mov %eax, %cr3 - // Setup registers pop %gs pop %fs @@ -37,8 +51,14 @@ task_switch: pop %eax // Perform the task switch + push %eax + mov 24(%esi), %eax + cmp $0x08, %eax # Check if we were in kernel mode + pop %eax + je skip_stack push 32(%esi) # ss push 36(%esi) # esp + skip_stack: push 68(%esi) # eflags push 24(%esi) # cs push 28(%esi) # eip |