nuclear@52: #include <stdio.h>
nuclear@47: #include <string.h>
nuclear@52: #include <assert.h>
nuclear@55: #include "config.h"
nuclear@42: #include "proc.h"
nuclear@42: #include "tss.h"
nuclear@45: #include "vm.h"
nuclear@47: #include "segm.h"
nuclear@47: #include "intr.h"
nuclear@47: #include "panic.h"
nuclear@51: #include "syscall.h"
nuclear@51: #include "sched.h"
nuclear@54: #include "tss.h"
nuclear@47: 
nuclear@55: #define	FLAGS_INTR_BIT	(1 << 9)
nuclear@47: 
nuclear@54: static void start_first_proc(void);
nuclear@54: 
nuclear@55: /* defined in proc-asm.S */
nuclear@55: uint32_t switch_stack(uint32_t new_stack);
nuclear@54: 
nuclear@47: /* defined in test_proc.S */
nuclear@47: void test_proc(void);
nuclear@47: void test_proc_end(void);
nuclear@42: 
nuclear@42: static struct process proc[MAX_PROC];
nuclear@56: 
nuclear@56: /* cur_pid:  pid of the currently executing process.
nuclear@56:  *           when we're in the idle process cur_pid will be 0.
nuclear@56:  * last_pid: pid of the last real process that was running, this should
nuclear@56:  *           never become 0. Essentially this defines the active kernel stack.
nuclear@56:  */
nuclear@56: static int cur_pid, last_pid;
nuclear@42: 
nuclear@54: static struct task_state *tss;
nuclear@54: 
nuclear@54: 
nuclear@42: void init_proc(void)
nuclear@42: {
nuclear@54: 	int tss_page;
nuclear@51: 
nuclear@54: 	/* allocate a page for the task state segment, to make sure
nuclear@54: 	 * it doesn't cross page boundaries
nuclear@54: 	 */
nuclear@54: 	if((tss_page = pgalloc(1, MEM_KERNEL)) == -1) {
nuclear@54: 		panic("failed to allocate memory for the task state segment\n");
nuclear@54: 	}
nuclear@55: 	tss = (struct task_state*)PAGE_TO_ADDR(tss_page);
nuclear@54: 
nuclear@54: 	/* the kernel stack segment never changes so we might as well set it now
nuclear@54: 	 * the only other thing that we use in the tss is the kernel stack pointer
nuclear@54: 	 * which is different for each process, and thus managed by context_switch
nuclear@54: 	 */
nuclear@54: 	memset(tss, 0, sizeof *tss);
nuclear@54: 	tss->ss0 = selector(SEGM_KDATA, 0);
nuclear@54: 
nuclear@55: 	set_tss((uint32_t)tss);
nuclear@54: 
nuclear@54: 	/* initialize system call handler (see syscall.c) */
nuclear@51: 	init_syscall();
nuclear@42: 
nuclear@54: 	start_first_proc(); /* XXX never returns */
nuclear@54: }
nuclear@54: 
nuclear@54: 
nuclear@54: static void start_first_proc(void)
nuclear@54: {
nuclear@54: 	struct process *p;
nuclear@54: 	int proc_size_pg, img_start_pg, stack_pg;
nuclear@55: 	uint32_t img_start_addr;
nuclear@54: 	struct intr_frame ifrm;
nuclear@54: 
nuclear@42: 	/* prepare the first process */
nuclear@54: 	p = proc + 1;
nuclear@54: 	p->id = 1;
nuclear@54: 	p->parent = 0;	/* no parent for init */
nuclear@42: 
nuclear@55: 	p->ticks_left = TIMESLICE_TICKS;
nuclear@55: 	p->next = p->prev = 0;
nuclear@55: 
nuclear@55: 	/* the first process may keep this existing page table */
nuclear@55: 	p->ctx.pgtbl_paddr = get_pgdir_addr();
nuclear@55: 
nuclear@42: 	/* allocate a chunk of memory for the process image
nuclear@42: 	 * and copy the code of test_proc there.
nuclear@42: 	 */
nuclear@51: 	proc_size_pg = (test_proc_end - test_proc) / PGSIZE + 1;
nuclear@45: 	if((img_start_pg = pgalloc(proc_size_pg, MEM_USER)) == -1) {
nuclear@45: 		panic("failed to allocate space for the init process image\n");
nuclear@45: 	}
nuclear@54: 	img_start_addr = PAGE_TO_ADDR(img_start_pg);
nuclear@54: 	memcpy((void*)img_start_addr, test_proc, proc_size_pg * PGSIZE);
nuclear@54: 	printf("copied init process at: %x\n", img_start_addr);
nuclear@47: 
nuclear@47: 	/* allocate the first page of the process stack */
nuclear@47: 	stack_pg = ADDR_TO_PAGE(KMEM_START) - 1;
nuclear@47: 	if(pgalloc_vrange(stack_pg, 1) == -1) {
nuclear@47: 		panic("failed to allocate user stack page\n");
nuclear@47: 	}
nuclear@54: 	p->user_stack_pg = stack_pg;
nuclear@52: 
nuclear@54: 	/* allocate a kernel stack for this process */
nuclear@54: 	if((p->kern_stack_pg = pgalloc(KERN_STACK_SIZE / PGSIZE, MEM_KERNEL)) == -1) {
nuclear@54: 		panic("failed to allocate kernel stack for the init process\n");
nuclear@54: 	}
nuclear@54: 	/* when switching from user space to kernel space, the ss0:esp0 from TSS
nuclear@54: 	 * will be used to switch to the per-process kernel stack, so we need to
nuclear@54: 	 * set it correctly before switching to user space.
nuclear@54: 	 * tss->ss0 is already set in init_proc above.
nuclear@54: 	 */
nuclear@54: 	tss->esp0 = PAGE_TO_ADDR(p->kern_stack_pg) + KERN_STACK_SIZE;
nuclear@45: 
nuclear@45: 
nuclear@54: 	/* now we need to fill in the fake interrupt stack frame */
nuclear@54: 	memset(&ifrm, 0, sizeof ifrm);
nuclear@54: 	/* after the priviledge switch, this ss:esp will be used in userspace */
nuclear@54: 	ifrm.esp = PAGE_TO_ADDR(stack_pg) + PGSIZE;
nuclear@54: 	ifrm.ss = selector(SEGM_UDATA, 3);
nuclear@54: 	/* instruction pointer at the beginning of the process image */
nuclear@55: 	ifrm.eip = img_start_addr;
nuclear@54: 	ifrm.cs = selector(SEGM_UCODE, 3);
nuclear@54: 	/* make sure the user will run with interrupts enabled */
nuclear@54: 	ifrm.eflags = FLAGS_INTR_BIT;
nuclear@54: 	/* user data selectors should all be the same */
nuclear@54: 	ifrm.ds = ifrm.es = ifrm.fs = ifrm.gs = ifrm.ss;
nuclear@42: 
nuclear@51: 	/* add it to the scheduler queues */
nuclear@55: 	add_proc(p->id);
nuclear@55: 
nuclear@56: 	/* make it current */
nuclear@56: 	set_current_pid(p->id);
nuclear@42: 
nuclear@54: 	/* execute a fake return from interrupt with the fake stack frame */
nuclear@54: 	intr_ret(ifrm);
nuclear@42: }
nuclear@42: 
nuclear@47: 
nuclear@47: void context_switch(int pid)
nuclear@42: {
nuclear@56: 	static struct process *prev, *new;
nuclear@49: 
nuclear@55: 	assert(get_intr_state() == 0);
nuclear@56: 	assert(pid > 0);
nuclear@56: 	assert(last_pid > 0);
nuclear@55: 
nuclear@56: 	prev = proc + last_pid;
nuclear@54: 	new = proc + pid;
nuclear@52: 
nuclear@56: 	if(last_pid != pid) {
nuclear@56: 		/* push all registers onto the stack before switching stacks */
nuclear@56: 		push_regs();
nuclear@47: 
nuclear@56: 		prev->ctx.stack_ptr = switch_stack(new->ctx.stack_ptr);
nuclear@47: 
nuclear@56: 		/* restore registers from the new stack */
nuclear@56: 		pop_regs();
nuclear@47: 
nuclear@56: 		/* switch to the new process' address space */
nuclear@56: 		set_pgdir_addr(new->ctx.pgtbl_paddr);
nuclear@47: 
nuclear@56: 		/* make sure we'll return to the correct kernel stack next time
nuclear@56: 		 * we enter from userspace
nuclear@56: 		 */
nuclear@56: 		tss->esp0 = PAGE_TO_ADDR(new->kern_stack_pg) + KERN_STACK_SIZE;
nuclear@56: 	}
nuclear@56: 
nuclear@56: 	set_current_pid(new->id);
nuclear@56: }
nuclear@56: 
nuclear@56: 
nuclear@56: void set_current_pid(int pid)
nuclear@56: {
nuclear@56: 	cur_pid = pid;
nuclear@56: 	if(pid > 0) {
nuclear@56: 		last_pid = pid;
nuclear@56: 	}
nuclear@47: }
nuclear@51: 
nuclear@51: int get_current_pid(void)
nuclear@51: {
nuclear@51: 	return cur_pid;
nuclear@51: }
nuclear@51: 
nuclear@51: struct process *get_current_proc(void)
nuclear@51: {
nuclear@56: 	return cur_pid > 0 ? &proc[cur_pid] : 0;
nuclear@51: }
nuclear@51: 
nuclear@51: struct process *get_process(int pid)
nuclear@51: {
nuclear@51: 	return &proc[pid];
nuclear@51: }