From 98d524bc8acb7b19afb693afea3ac77629d6f4bf Mon Sep 17 00:00:00 2001 From: Loic Guegan Date: Fri, 16 Apr 2021 14:39:24 +0200 Subject: [PATCH] Multitasking works! --- src/bringelle.c | 39 +++++++++++----- src/core/idt.c | 2 +- src/core/paging.c | 2 +- src/core/paging.h | 8 +++- src/core/scheduler.c | 99 +++++++++++++++++++++++++--------------- src/core/scheduler.h | 4 +- src/core/scheduler_asm.S | 39 ++++++++-------- 7 files changed, 121 insertions(+), 72 deletions(-) diff --git a/src/bringelle.c b/src/bringelle.c index cb8c5e4..38c066e 100644 --- a/src/bringelle.c +++ b/src/bringelle.c @@ -9,14 +9,26 @@ extern void interrupt_enable(); void utask(){ char *msg=(char*)4206592+10; - msg[0]='T'; - msg[1]='a'; - msg[2]='s'; - msg[3]='k'; - msg[4]='1'; - msg[5]='\0'; - asm("mov $0x1, %%eax;int $0x30"::"b"(msg)); - while(1); + msg[0]='A'; + msg[1]='\0'; + while(1){ + asm("mov $0x1, %%eax;int $0x30"::"b"(msg)); + 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"); - int* page_dir=paging_allocate(2); - run_task(page_dir, utask,100); + print("Launch user tasks \n"); + 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); } diff --git a/src/core/idt.c b/src/core/idt.c index 4e08d62..5acdf8b 100644 --- a/src/core/idt.c +++ b/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)"); diff --git a/src/core/paging.c b/src/core/paging.c index 0fab46a..ab853bb 100644 --- a/src/core/paging.c +++ b/src/core/paging.c @@ -110,7 +110,7 @@ int *paging_allocate(int p){ u_page_table[1]=(int)k_page_table|7; u_page_table[2]=(int)u_page_table|7; u_page_table[3]=(int)paging_allocate_next_page()|7; - + return page_dir; } diff --git a/src/core/paging.h b/src/core/paging.h index 5329384..34eddff 100644 --- a/src/core/paging.h +++ b/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 diff --git a/src/core/scheduler.c b/src/core/scheduler.c index 0a8c5c7..fffeaf2 100644 --- a/src/core/scheduler.c +++ b/src/core/scheduler.c @@ -9,16 +9,14 @@ 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) return; @@ -47,7 +45,8 @@ 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; asm("mov %%ss, %0": "=m" (TSS.ss0)); @@ -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=(void*)(PADDR(pt_addr[3])); - void *ustack=(void*)((int)entry_point+0xFF); + void *entry_point=PAGING_ENTRY_POINT_VIRT; + void *ustack=(void*)(PAGING_ENTRY_POINT_VIRT+0xFF); // Load the task into memory - memcpy(task,entry_point, task_size); - - // Load page directory - asm( - "mov %0, %%eax \n\t" - "mov %%eax,%%cr3 \n\t" - :: "b"(page_dir) - ); + memcpy(task,PAGING_ENTRY_POINT_PHY(page_dir), task_size); - // Setup users adresses - - // Switch to user task + // 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 ( - "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 - "push $0x23 \n\t" // Push task cs which is 0x20 along with prlv which is 0x3 - "push %3 \n\t" // Push task entry point - "mov $0x2B, %%eax \n\t" // GDT entry 0x28 along with prlv which is 0x3 - "mov %%eax, %%ds \n\t" // Setting up user data segment - "iret \n\t" // Launch user task - : "=m" (TSS.ss0), "=m" (TSS.esp0) - : "b" (ustack), "c" (entry_point) - ); + "mov %%eax, %0 \n\t" // Get flags into eflag + : "=m" (eflags) + ); + p->regs.eflags=eflags; + + // Setup other attributes + p->id=nproc; + 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) + ); + } } \ No newline at end of file diff --git a/src/core/scheduler.h b/src/core/scheduler.h index 9055fda..fbcf6bd 100644 --- a/src/core/scheduler.h +++ b/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 \ No newline at end of file diff --git a/src/core/scheduler_asm.S b/src/core/scheduler_asm.S index 92e3f2e..1f916ec 100644 --- a/src/core/scheduler_asm.S +++ b/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) - push 16(%esi) # ebx - push 20(%esi) # ecx - push 24(%esi) # edx - push 44(%esi) # ebp - push 48(%esi) # esi - push 52(%esi) # edi - push 56(%esi) # ds - push 60(%esi) # es - push 64(%esi) # fs - push 68(%esi) # gs + pop %esi + push 8(%esi) # eax (cf PROC struct) + push 12(%esi) # ebx + push 16(%esi) # ecx + push 20(%esi) # edx + push 40(%esi) # ebp + push 48(%esi) # edi + push 52(%esi) # ds + push 56(%esi) # es + push 60(%esi) # fs + 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 40(%esi) # esp - push 72(%esi) # eflags - push 28(%esi) # cs - push 32(%esi) # eip - iret + push 32(%esi) # ss + push 36(%esi) # esp + push 68(%esi) # eflags + push 24(%esi) # cs + push 28(%esi) # eip + mov 52(%esi), %ds # Choose the right data segment + mov 44(%esi), %esi # Now restore task esi + iret # Launch task