482 lines
10 KiB
C
482 lines
10 KiB
C
#include "types.h"
|
|
#include "defs.h"
|
|
#include "param.h"
|
|
#include "mmu.h"
|
|
#include "x86.h"
|
|
#include "proc.h"
|
|
#include "spinlock.h"
|
|
|
|
struct {
|
|
struct spinlock lock;
|
|
struct proc proc[NPROC];
|
|
} ptable;
|
|
|
|
static struct proc *initproc;
|
|
|
|
int nextpid = 1;
|
|
extern void forkret(void);
|
|
extern void trapret(void);
|
|
|
|
void
|
|
pinit(void)
|
|
{
|
|
initlock(&ptable.lock, "ptable");
|
|
}
|
|
|
|
//PAGEBREAK: 36
|
|
// Print a process listing to console. For debugging.
|
|
// Runs when user types ^P on console.
|
|
// No lock to avoid wedging a stuck machine further.
|
|
void
|
|
procdump(void)
|
|
{
|
|
static char *states[] = {
|
|
[UNUSED] "unused",
|
|
[EMBRYO] "embryo",
|
|
[SLEEPING] "sleep ",
|
|
[RUNNABLE] "runble",
|
|
[RUNNING] "run ",
|
|
[ZOMBIE] "zombie"
|
|
};
|
|
int i;
|
|
struct proc *p;
|
|
char *state;
|
|
uint pc[10];
|
|
|
|
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
|
|
if(p->state == UNUSED)
|
|
continue;
|
|
if(p->state >= 0 && p->state < NELEM(states) && states[p->state])
|
|
state = states[p->state];
|
|
else
|
|
state = "???";
|
|
cprintf("%d %s %s", p->pid, state, p->name);
|
|
if(p->state == SLEEPING){
|
|
getcallerpcs((uint*)p->context->ebp+2, pc);
|
|
for(i=0; i<10 && pc[i] != 0; i++)
|
|
cprintf(" %p", pc[i]);
|
|
}
|
|
cprintf("\n");
|
|
}
|
|
}
|
|
|
|
// Set up CPU's kernel segment descriptors.
|
|
// Run once at boot time on each CPU.
|
|
void
|
|
ksegment(void)
|
|
{
|
|
struct cpu *c;
|
|
|
|
c = &cpus[cpunum()];
|
|
c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0x100000 + 64*1024-1, 0);
|
|
c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
|
|
c->gdt[SEG_KCPU] = SEG(STA_W, &c->tlsstruct, 0xffffffff, 0);
|
|
lgdt(c->gdt, sizeof(c->gdt));
|
|
loadfsgs(SEG_KCPU << 3);
|
|
|
|
// Initialize cpu-local storage.
|
|
c->tlsstruct = &c->tlsstruct;
|
|
asm volatile(""); // Do not let gcc reorder across this line.
|
|
cpu = c;
|
|
proc = 0;
|
|
}
|
|
|
|
// Set up CPU's segment descriptors and current process task state.
|
|
void
|
|
usegment(void)
|
|
{
|
|
pushcli();
|
|
cpu->gdt[SEG_UCODE] = SEG(STA_X|STA_R, proc->mem, proc->sz-1, DPL_USER);
|
|
cpu->gdt[SEG_UDATA] = SEG(STA_W, proc->mem, proc->sz-1, DPL_USER);
|
|
cpu->gdt[SEG_TSS] = SEG16(STS_T32A, &cpu->ts, sizeof(cpu->ts)-1, 0);
|
|
cpu->gdt[SEG_TSS].s = 0;
|
|
cpu->ts.ss0 = SEG_KDATA << 3;
|
|
cpu->ts.esp0 = (uint)proc->kstack + KSTACKSIZE;
|
|
ltr(SEG_TSS << 3);
|
|
popcli();
|
|
}
|
|
|
|
//PAGEBREAK: 15
|
|
// Look in the process table for an UNUSED proc.
|
|
// If found, change state to EMBRYO and return it.
|
|
// Otherwise return 0.
|
|
static struct proc*
|
|
allocproc(void)
|
|
{
|
|
struct proc *p;
|
|
char *sp;
|
|
|
|
acquire(&ptable.lock);
|
|
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
|
|
if(p->state == UNUSED)
|
|
goto found;
|
|
release(&ptable.lock);
|
|
return 0;
|
|
|
|
found:
|
|
p->state = EMBRYO;
|
|
p->pid = nextpid++;
|
|
release(&ptable.lock);
|
|
|
|
// Allocate kernel stack if necessary.
|
|
if((p->kstack = kalloc(KSTACKSIZE)) == 0){
|
|
p->state = UNUSED;
|
|
return 0;
|
|
}
|
|
sp = p->kstack + KSTACKSIZE;
|
|
|
|
// Leave room for trap frame.
|
|
sp -= sizeof *p->tf;
|
|
p->tf = (struct trapframe*)sp;
|
|
|
|
// Set up new context to start executing at forkret,
|
|
// which returns to trapret (see below).
|
|
sp -= 4;
|
|
*(uint*)sp = (uint)trapret;
|
|
|
|
sp -= sizeof *p->context;
|
|
p->context = (struct context*)sp;
|
|
memset(p->context, 0, sizeof *p->context);
|
|
p->context->eip = (uint)forkret;
|
|
return p;
|
|
}
|
|
|
|
// Set up first user process.
|
|
void
|
|
userinit(void)
|
|
{
|
|
struct proc *p;
|
|
extern char _binary_initcode_start[], _binary_initcode_size[];
|
|
|
|
p = allocproc();
|
|
initproc = p;
|
|
|
|
// Initialize memory from initcode.S
|
|
p->sz = PAGE;
|
|
p->mem = kalloc(p->sz);
|
|
memset(p->mem, 0, p->sz);
|
|
memmove(p->mem, _binary_initcode_start, (int)_binary_initcode_size);
|
|
|
|
memset(p->tf, 0, sizeof(*p->tf));
|
|
p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
|
|
p->tf->ds = (SEG_UDATA << 3) | DPL_USER;
|
|
p->tf->es = p->tf->ds;
|
|
p->tf->ss = p->tf->ds;
|
|
p->tf->eflags = FL_IF;
|
|
p->tf->esp = p->sz;
|
|
p->tf->eip = 0; // beginning of initcode.S
|
|
|
|
safestrcpy(p->name, "initcode", sizeof(p->name));
|
|
p->cwd = namei("/");
|
|
|
|
p->state = RUNNABLE;
|
|
}
|
|
|
|
// Grow current process's memory by n bytes.
|
|
// Return 0 on success, -1 on failure.
|
|
int
|
|
growproc(int n)
|
|
{
|
|
char *newmem;
|
|
|
|
newmem = kalloc(proc->sz + n);
|
|
if(newmem == 0)
|
|
return -1;
|
|
memmove(newmem, proc->mem, proc->sz);
|
|
memset(newmem + proc->sz, 0, n);
|
|
kfree(proc->mem, proc->sz);
|
|
proc->mem = newmem;
|
|
proc->sz += n;
|
|
usegment();
|
|
return 0;
|
|
}
|
|
|
|
// Create a new process copying p as the parent.
|
|
// Sets up stack to return as if from system call.
|
|
// Caller must set state of returned proc to RUNNABLE.
|
|
int
|
|
fork(void)
|
|
{
|
|
int i, pid;
|
|
struct proc *np;
|
|
|
|
// Allocate process.
|
|
if((np = allocproc()) == 0)
|
|
return -1;
|
|
|
|
// Copy process state from p.
|
|
np->sz = proc->sz;
|
|
if((np->mem = kalloc(np->sz)) == 0){
|
|
kfree(np->kstack, KSTACKSIZE);
|
|
np->kstack = 0;
|
|
np->state = UNUSED;
|
|
return -1;
|
|
}
|
|
memmove(np->mem, proc->mem, np->sz);
|
|
np->parent = proc;
|
|
*np->tf = *proc->tf;
|
|
|
|
// Clear %eax so that fork returns 0 in the child.
|
|
np->tf->eax = 0;
|
|
|
|
for(i = 0; i < NOFILE; i++)
|
|
if(proc->ofile[i])
|
|
np->ofile[i] = filedup(proc->ofile[i]);
|
|
np->cwd = idup(proc->cwd);
|
|
|
|
pid = np->pid;
|
|
np->state = RUNNABLE;
|
|
|
|
return pid;
|
|
}
|
|
|
|
//PAGEBREAK: 42
|
|
// Per-CPU process scheduler.
|
|
// Each CPU calls scheduler() after setting itself up.
|
|
// Scheduler never returns. It loops, doing:
|
|
// - choose a process to run
|
|
// - swtch to start running that process
|
|
// - eventually that process transfers control
|
|
// via swtch back to the scheduler.
|
|
void
|
|
scheduler(void)
|
|
{
|
|
struct proc *p;
|
|
|
|
for(;;){
|
|
// Enable interrupts on this processor.
|
|
sti();
|
|
|
|
// Loop over process table looking for process to run.
|
|
acquire(&ptable.lock);
|
|
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
|
|
if(p->state != RUNNABLE)
|
|
continue;
|
|
|
|
// Switch to chosen process. It is the process's job
|
|
// to release ptable.lock and then reacquire it
|
|
// before jumping back to us.
|
|
proc = p;
|
|
usegment();
|
|
p->state = RUNNING;
|
|
swtch(&cpu->scheduler, proc->context);
|
|
|
|
// Process is done running for now.
|
|
// It should have changed its p->state before coming back.
|
|
proc = 0;
|
|
}
|
|
release(&ptable.lock);
|
|
|
|
}
|
|
}
|
|
|
|
// Enter scheduler. Must hold only ptable.lock
|
|
// and have changed proc->state.
|
|
void
|
|
sched(void)
|
|
{
|
|
int intena;
|
|
|
|
if(!holding(&ptable.lock))
|
|
panic("sched ptable.lock");
|
|
if(cpu->ncli != 1)
|
|
panic("sched locks");
|
|
if(proc->state == RUNNING)
|
|
panic("sched running");
|
|
if(readeflags()&FL_IF)
|
|
panic("sched interruptible");
|
|
|
|
intena = cpu->intena;
|
|
swtch(&proc->context, cpu->scheduler);
|
|
cpu->intena = intena;
|
|
}
|
|
|
|
// Give up the CPU for one scheduling round.
|
|
void
|
|
yield(void)
|
|
{
|
|
acquire(&ptable.lock); //DOC: yieldlock
|
|
proc->state = RUNNABLE;
|
|
sched();
|
|
release(&ptable.lock);
|
|
}
|
|
|
|
// A fork child's very first scheduling by scheduler()
|
|
// will swtch here. "Return" to user space.
|
|
void
|
|
forkret(void)
|
|
{
|
|
// Still holding ptable.lock from scheduler.
|
|
release(&ptable.lock);
|
|
|
|
// Return to "caller", actually trapret (see allocproc).
|
|
}
|
|
|
|
// Atomically release lock and sleep on chan.
|
|
// Reacquires lock when awakened.
|
|
void
|
|
sleep(void *chan, struct spinlock *lk)
|
|
{
|
|
if(proc == 0)
|
|
panic("sleep");
|
|
|
|
if(lk == 0)
|
|
panic("sleep without lk");
|
|
|
|
// Must acquire ptable.lock in order to
|
|
// change p->state and then call sched.
|
|
// Once we hold ptable.lock, we can be
|
|
// guaranteed that we won't miss any wakeup
|
|
// (wakeup runs with ptable.lock locked),
|
|
// so it's okay to release lk.
|
|
if(lk != &ptable.lock){ //DOC: sleeplock0
|
|
acquire(&ptable.lock); //DOC: sleeplock1
|
|
release(lk);
|
|
}
|
|
|
|
// Go to sleep.
|
|
proc->chan = chan;
|
|
proc->state = SLEEPING;
|
|
sched();
|
|
|
|
// Tidy up.
|
|
proc->chan = 0;
|
|
|
|
// Reacquire original lock.
|
|
if(lk != &ptable.lock){ //DOC: sleeplock2
|
|
release(&ptable.lock);
|
|
acquire(lk);
|
|
}
|
|
}
|
|
|
|
//PAGEBREAK!
|
|
// Wake up all processes sleeping on chan.
|
|
// The ptable lock must be held.
|
|
static void
|
|
wakeup1(void *chan)
|
|
{
|
|
struct proc *p;
|
|
|
|
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
|
|
if(p->state == SLEEPING && p->chan == chan)
|
|
p->state = RUNNABLE;
|
|
}
|
|
|
|
// Wake up all processes sleeping on chan.
|
|
void
|
|
wakeup(void *chan)
|
|
{
|
|
acquire(&ptable.lock);
|
|
wakeup1(chan);
|
|
release(&ptable.lock);
|
|
}
|
|
|
|
// Kill the process with the given pid.
|
|
// Process won't exit until it returns
|
|
// to user space (see trap in trap.c).
|
|
int
|
|
kill(int pid)
|
|
{
|
|
struct proc *p;
|
|
|
|
acquire(&ptable.lock);
|
|
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
|
|
if(p->pid == pid){
|
|
p->killed = 1;
|
|
// Wake process from sleep if necessary.
|
|
if(p->state == SLEEPING)
|
|
p->state = RUNNABLE;
|
|
release(&ptable.lock);
|
|
return 0;
|
|
}
|
|
}
|
|
release(&ptable.lock);
|
|
return -1;
|
|
}
|
|
|
|
// Exit the current process. Does not return.
|
|
// An exited process remains in the zombie state
|
|
// until its parent calls wait() to find out it exited.
|
|
void
|
|
exit(void)
|
|
{
|
|
struct proc *p;
|
|
int fd;
|
|
|
|
if(proc == initproc)
|
|
panic("init exiting");
|
|
|
|
// Close all open files.
|
|
for(fd = 0; fd < NOFILE; fd++){
|
|
if(proc->ofile[fd]){
|
|
fileclose(proc->ofile[fd]);
|
|
proc->ofile[fd] = 0;
|
|
}
|
|
}
|
|
|
|
iput(proc->cwd);
|
|
proc->cwd = 0;
|
|
|
|
acquire(&ptable.lock);
|
|
|
|
// Parent might be sleeping in wait().
|
|
wakeup1(proc->parent);
|
|
|
|
// Pass abandoned children to init.
|
|
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
|
|
if(p->parent == proc){
|
|
p->parent = initproc;
|
|
if(p->state == ZOMBIE)
|
|
wakeup1(initproc);
|
|
}
|
|
}
|
|
|
|
// Jump into the scheduler, never to return.
|
|
proc->state = ZOMBIE;
|
|
sched();
|
|
panic("zombie exit");
|
|
}
|
|
|
|
// Wait for a child process to exit and return its pid.
|
|
// Return -1 if this process has no children.
|
|
int
|
|
wait(void)
|
|
{
|
|
struct proc *p;
|
|
int havekids, pid;
|
|
|
|
acquire(&ptable.lock);
|
|
for(;;){
|
|
// Scan through table looking for zombie children.
|
|
havekids = 0;
|
|
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
|
|
if(p->parent != proc)
|
|
continue;
|
|
havekids = 1;
|
|
if(p->state == ZOMBIE){
|
|
// Found one.
|
|
pid = p->pid;
|
|
kfree(p->mem, p->sz);
|
|
kfree(p->kstack, KSTACKSIZE);
|
|
p->state = UNUSED;
|
|
p->pid = 0;
|
|
p->parent = 0;
|
|
p->name[0] = 0;
|
|
p->killed = 0;
|
|
release(&ptable.lock);
|
|
return pid;
|
|
}
|
|
}
|
|
|
|
// No point waiting if we don't have any children.
|
|
if(!havekids || proc->killed){
|
|
release(&ptable.lock);
|
|
return -1;
|
|
}
|
|
|
|
// Wait for children to exit. (See wakeup1 call in proc_exit.)
|
|
sleep(proc, &ptable.lock); //DOC: wait-sleep
|
|
}
|
|
}
|
|
|