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413 lines
8.0 KiB
413 lines
8.0 KiB
/*
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* linux/kernel/sched.c
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*
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* (C) 1991 Linus Torvalds
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*/
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/*
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* 'sched.c' is the main kernel file. It contains scheduling primitives
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* (sleep_on, wakeup, schedule etc) as well as a number of simple system
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* call functions (type getpid(), which just extracts a field from
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* current-task
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*/
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/sys.h>
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#include <linux/fdreg.h>
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#include <asm/system.h>
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#include <asm/io.h>
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#include <asm/segment.h>
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#include <signal.h>
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#define _S(nr) (1<<((nr)-1))
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#define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
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void show_task(int nr,struct task_struct * p)
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{
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int i,j = 4096-sizeof(struct task_struct);
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printk("%d: pid=%d, state=%d, ",nr,p->pid,p->state);
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i=0;
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while (i<j && !((char *)(p+1))[i])
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i++;
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printk("%d (of %d) chars free in kernel stack\n\r",i,j);
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}
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void show_stat(void)
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{
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int i;
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for (i=0;i<NR_TASKS;i++)
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if (task[i])
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show_task(i,task[i]);
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}
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#define LATCH (1193180/HZ)
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extern void mem_use(void);
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extern int timer_interrupt(void);
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extern int system_call(void);
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union task_union {
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struct task_struct task;
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char stack[PAGE_SIZE];
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};
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static union task_union init_task = {INIT_TASK,};
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long volatile jiffies=0;
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long startup_time=0;
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struct task_struct *current = &(init_task.task);
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struct task_struct *last_task_used_math = NULL;
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struct task_struct * task[NR_TASKS] = {&(init_task.task), };
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long user_stack [ PAGE_SIZE>>2 ] ;
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struct {
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long * a;
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short b;
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} stack_start = { & user_stack [PAGE_SIZE>>2] , 0x10 };
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/*
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* 'math_state_restore()' saves the current math information in the
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* old math state array, and gets the new ones from the current task
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*/
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void math_state_restore()
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{
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if (last_task_used_math == current)
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return;
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__asm__("fwait");
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if (last_task_used_math) {
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__asm__("fnsave %0"::"m" (last_task_used_math->tss.i387));
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}
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last_task_used_math=current;
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if (current->used_math) {
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__asm__("frstor %0"::"m" (current->tss.i387));
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} else {
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__asm__("fninit"::);
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current->used_math=1;
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}
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}
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/*
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* 'schedule()' is the scheduler function. This is GOOD CODE! There
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* probably won't be any reason to change this, as it should work well
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* in all circumstances (ie gives IO-bound processes good response etc).
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* The one thing you might take a look at is the signal-handler code here.
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*
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* NOTE!! Task 0 is the 'idle' task, which gets called when no other
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* tasks can run. It can not be killed, and it cannot sleep. The 'state'
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* information in task[0] is never used.
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*/
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void schedule(void)
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{
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int i,next,c;
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struct task_struct ** p;
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/* check alarm, wake up any interruptible tasks that have got a signal */
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for(p = &LAST_TASK ; p > &FIRST_TASK ; --p)
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if (*p) {
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if ((*p)->alarm && (*p)->alarm < jiffies) {
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(*p)->signal |= (1<<(SIGALRM-1));
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(*p)->alarm = 0;
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}
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if (((*p)->signal & ~(_BLOCKABLE & (*p)->blocked)) &&
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(*p)->state==TASK_INTERRUPTIBLE)
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(*p)->state=TASK_RUNNING;
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}
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/* this is the scheduler proper: */
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while (1) {
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c = -1;
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next = 0;
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i = NR_TASKS;
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p = &task[NR_TASKS];
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while (--i) {
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if (!*--p)
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continue;
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if ((*p)->state == TASK_RUNNING && (*p)->counter > c)
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c = (*p)->counter, next = i;
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}
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if (c) break;
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for(p = &LAST_TASK ; p > &FIRST_TASK ; --p)
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if (*p)
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(*p)->counter = ((*p)->counter >> 1) +
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(*p)->priority;
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}
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switch_to(next);
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}
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int sys_pause(void)
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{
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current->state = TASK_INTERRUPTIBLE;
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schedule();
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return 0;
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}
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void sleep_on(struct task_struct **p)
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{
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struct task_struct *tmp;
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if (!p)
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return;
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if (current == &(init_task.task))
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panic("task[0] trying to sleep");
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tmp = *p;
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*p = current;
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current->state = TASK_UNINTERRUPTIBLE;
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schedule();
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if (tmp)
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tmp->state=0;
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}
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void interruptible_sleep_on(struct task_struct **p)
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{
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struct task_struct *tmp;
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if (!p)
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return;
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if (current == &(init_task.task))
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panic("task[0] trying to sleep");
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tmp=*p;
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*p=current;
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repeat: current->state = TASK_INTERRUPTIBLE;
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schedule();
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if (*p && *p != current) {
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(**p).state=0;
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goto repeat;
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}
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*p=NULL;
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if (tmp)
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tmp->state=0;
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}
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void wake_up(struct task_struct **p)
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{
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if (p && *p) {
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(**p).state=0;
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*p=NULL;
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}
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}
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/*
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* OK, here are some floppy things that shouldn't be in the kernel
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* proper. They are here because the floppy needs a timer, and this
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* was the easiest way of doing it.
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*/
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static struct task_struct * wait_motor[4] = {NULL,NULL,NULL,NULL};
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static int mon_timer[4]={0,0,0,0};
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static int moff_timer[4]={0,0,0,0};
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unsigned char current_DOR = 0x0C;
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int ticks_to_floppy_on(unsigned int nr)
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{
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extern unsigned char selected;
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unsigned char mask = 0x10 << nr;
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if (nr>3)
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panic("floppy_on: nr>3");
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moff_timer[nr]=10000; /* 100 s = very big :-) */
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cli(); /* use floppy_off to turn it off */
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mask |= current_DOR;
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if (!selected) {
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mask &= 0xFC;
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mask |= nr;
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}
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if (mask != current_DOR) {
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outb(mask,FD_DOR);
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if ((mask ^ current_DOR) & 0xf0)
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mon_timer[nr] = HZ/2;
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else if (mon_timer[nr] < 2)
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mon_timer[nr] = 2;
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current_DOR = mask;
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}
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sti();
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return mon_timer[nr];
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}
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void floppy_on(unsigned int nr)
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{
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cli();
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while (ticks_to_floppy_on(nr))
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sleep_on(nr+wait_motor);
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sti();
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}
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void floppy_off(unsigned int nr)
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{
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moff_timer[nr]=3*HZ;
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}
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void do_floppy_timer(void)
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{
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int i;
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unsigned char mask = 0x10;
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for (i=0 ; i<4 ; i++,mask <<= 1) {
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if (!(mask & current_DOR))
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continue;
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if (mon_timer[i]) {
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if (!--mon_timer[i])
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wake_up(i+wait_motor);
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} else if (!moff_timer[i]) {
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current_DOR &= ~mask;
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outb(current_DOR,FD_DOR);
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} else
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moff_timer[i]--;
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}
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}
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#define TIME_REQUESTS 64
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static struct timer_list {
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long jiffies;
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void (*fn)();
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struct timer_list * next;
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} timer_list[TIME_REQUESTS], * next_timer = NULL;
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void add_timer(long jiffies, void (*fn)(void))
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{
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struct timer_list * p;
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if (!fn)
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return;
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cli();
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if (jiffies <= 0)
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(fn)();
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else {
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for (p = timer_list ; p < timer_list + TIME_REQUESTS ; p++)
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if (!p->fn)
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break;
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if (p >= timer_list + TIME_REQUESTS)
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panic("No more time requests free");
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p->fn = fn;
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p->jiffies = jiffies;
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p->next = next_timer;
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next_timer = p;
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while (p->next && p->next->jiffies < p->jiffies) {
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p->jiffies -= p->next->jiffies;
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fn = p->fn;
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p->fn = p->next->fn;
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p->next->fn = fn;
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jiffies = p->jiffies;
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p->jiffies = p->next->jiffies;
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p->next->jiffies = jiffies;
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p = p->next;
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}
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}
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sti();
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}
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void do_timer(long cpl)
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{
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extern int beepcount;
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extern void sysbeepstop(void);
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if (beepcount)
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if (!--beepcount)
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sysbeepstop();
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if (cpl)
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current->utime++;
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else
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current->stime++;
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if (next_timer) {
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next_timer->jiffies--;
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while (next_timer && next_timer->jiffies <= 0) {
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void (*fn)(void);
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fn = next_timer->fn;
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next_timer->fn = NULL;
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next_timer = next_timer->next;
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(fn)();
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}
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}
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if (current_DOR & 0xf0)
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do_floppy_timer();
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if ((--current->counter)>0) return;
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current->counter=0;
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if (!cpl) return;
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schedule();
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}
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int sys_alarm(long seconds)
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{
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int old = current->alarm;
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if (old)
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old = (old - jiffies) / HZ;
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current->alarm = (seconds>0)?(jiffies+HZ*seconds):0;
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return (old);
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}
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int sys_getpid(void)
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{
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return current->pid;
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}
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int sys_getppid(void)
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{
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return current->father;
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}
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int sys_getuid(void)
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{
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return current->uid;
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}
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int sys_geteuid(void)
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{
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return current->euid;
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}
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int sys_getgid(void)
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{
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return current->gid;
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}
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int sys_getegid(void)
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{
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return current->egid;
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}
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int sys_nice(long increment)
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{
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if (current->priority-increment>0)
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current->priority -= increment;
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return 0;
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}
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void sched_init(void)
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{
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int i;
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struct desc_struct * p;
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if (sizeof(struct sigaction) != 16)
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panic("Struct sigaction MUST be 16 bytes");
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set_tss_desc(gdt+FIRST_TSS_ENTRY,&(init_task.task.tss));
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set_ldt_desc(gdt+FIRST_LDT_ENTRY,&(init_task.task.ldt));
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p = gdt+2+FIRST_TSS_ENTRY;
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for(i=1;i<NR_TASKS;i++) {
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task[i] = NULL;
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p->a=p->b=0;
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p++;
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p->a=p->b=0;
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p++;
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}
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/* Clear NT, so that we won't have troubles with that later on */
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__asm__("pushfl ; andl $0xffffbfff,(%esp) ; popfl");
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ltr(0);
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lldt(0);
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outb_p(0x36,0x43); /* binary, mode 3, LSB/MSB, ch 0 */
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outb_p(LATCH & 0xff , 0x40); /* LSB */
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outb(LATCH >> 8 , 0x40); /* MSB */
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set_intr_gate(0x20,&timer_interrupt);
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outb(inb_p(0x21)&~0x01,0x21);
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set_system_gate(0x80,&system_call);
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}
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