Initial Upload
This commit is contained in:
iDunnoDev
527
proc.c
Normal file
527
proc.c
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@ -0,0 +1,527 @@
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#include "types.h"
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#include "defs.h"
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#include "param.h"
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#include "memlayout.h"
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#include "mmu.h"
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#include "x86.h"
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#include "proc.h"
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#include "spinlock.h"
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struct {
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struct spinlock lock;
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struct proc proc[NPROC];
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} ptable;
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static struct proc *initproc;
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int nextpid = 1;
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extern void forkret(void);
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extern void trapret(void);
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static void wakeup1(void *chan);
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void pinit(void) {
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initlock(&ptable.lock, "ptable");
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}
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// Must be called with interrupts disabled
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int cpuid() {
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return mycpu() - cpus;
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}
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// Must be called with interrupts disabled to avoid the caller being
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// rescheduled between reading lapicid and running through the loop.
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struct cpu*mycpu(void) {
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int apicid, i;
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if (readeflags() & FL_IF) {
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panic("mycpu called with interrupts enabled\n");
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}
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apicid = lapicid();
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// APIC IDs are not guaranteed to be contiguous. Maybe we should have
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// a reverse map, or reserve a register to store &cpus[i].
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for (i = 0; i < ncpu; ++i) {
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if (cpus[i].apicid == apicid) {
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return &cpus[i];
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}
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}
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panic("unknown apicid\n");
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}
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// Disable interrupts so that we are not rescheduled
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// while reading proc from the cpu structure
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struct proc*myproc(void) {
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struct cpu *c;
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struct proc *p;
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pushcli();
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c = mycpu();
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p = c->proc;
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popcli();
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return p;
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}
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// Look in the process table for an UNUSED proc.
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// If found, change state to EMBRYO and initialize
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// state required to run in the kernel.
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// Otherwise return 0.
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static struct proc* allocproc(void) {
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struct proc *p;
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char *sp;
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int found = 0;
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acquire(&ptable.lock);
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p = ptable.proc;
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while (p < &ptable.proc[NPROC] && !found) {
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if (p->state == UNUSED) {
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found = 1;
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}
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else {
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p++;
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}
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}
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if (!found) {
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release(&ptable.lock);
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return 0;
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}
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p->state = EMBRYO;
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p->pid = nextpid++;
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release(&ptable.lock);
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// Allocate kernel stack.
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if ((p->kstack = kalloc()) == 0) {
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p->state = UNUSED;
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return 0;
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}
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sp = p->kstack + KSTACKSIZE;
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// Leave room for trap frame.
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sp -= sizeof *p->tf;
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p->tf = (struct trapframe*)sp;
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// Set up new context to start executing at forkret,
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// which returns to trapret.
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sp -= 4;
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*(uint*)sp = (uint)trapret;
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sp -= sizeof *p->context;
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p->context = (struct context*)sp;
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memset(p->context, 0, sizeof *p->context);
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p->context->eip = (uint)forkret;
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return p;
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}
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// Set up first user process.
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void userinit(void) {
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struct proc *p;
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extern char _binary_initcode_start[], _binary_initcode_size[];
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p = allocproc();
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initproc = p;
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if ((p->pgdir = setupkvm()) == 0) {
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panic("userinit: out of memory?");
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}
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inituvm(p->pgdir, _binary_initcode_start, (int)_binary_initcode_size);
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p->sz = PGSIZE;
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memset(p->tf, 0, sizeof(*p->tf));
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p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
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p->tf->ds = (SEG_UDATA << 3) | DPL_USER;
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p->tf->es = p->tf->ds;
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p->tf->ss = p->tf->ds;
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p->tf->eflags = FL_IF;
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p->tf->esp = PGSIZE;
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p->tf->eip = 0; // beginning of initcode.S
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safestrcpy(p->name, "initcode", sizeof(p->name));
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p->cwd = namei("/");
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// this assignment to p->state lets other cores
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// run this process. the acquire forces the above
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// writes to be visible, and the lock is also needed
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// because the assignment might not be atomic.
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acquire(&ptable.lock);
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p->state = RUNNABLE;
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release(&ptable.lock);
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}
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// Grow current process's memory by n bytes.
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// Return 0 on success, -1 on failure.
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int growproc(int n) {
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uint sz;
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struct proc *curproc = myproc();
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sz = curproc->sz;
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if (n > 0) {
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if ((sz = allocuvm(curproc->pgdir, sz, sz + n)) == 0) {
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return -1;
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}
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}
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else if (n < 0) {
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if ((sz = deallocuvm(curproc->pgdir, sz, sz + n)) == 0) {
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return -1;
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}
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}
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curproc->sz = sz;
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switchuvm(curproc);
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return 0;
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}
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// Create a new process copying p as the parent.
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// Sets up stack to return as if from system call.
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// Caller must set state of returned proc to RUNNABLE.
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int fork(void) {
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int i, pid;
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struct proc *np;
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struct proc *curproc = myproc();
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// Allocate process.
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if ((np = allocproc()) == 0) {
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return -1;
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}
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// Copy process state from proc.
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if ((np->pgdir = copyuvm(curproc->pgdir, curproc->sz)) == 0) {
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kfree(np->kstack);
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np->kstack = 0;
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np->state = UNUSED;
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return -1;
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}
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np->sz = curproc->sz;
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np->parent = curproc;
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*np->tf = *curproc->tf;
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// Clear %eax so that fork returns 0 in the child.
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np->tf->eax = 0;
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for (i = 0; i < NOFILE; i++) {
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if (curproc->ofile[i]) {
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np->ofile[i] = filedup(curproc->ofile[i]);
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}
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}
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np->cwd = idup(curproc->cwd);
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safestrcpy(np->name, curproc->name, sizeof(curproc->name));
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pid = np->pid;
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acquire(&ptable.lock);
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np->state = RUNNABLE;
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release(&ptable.lock);
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return pid;
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}
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// Exit the current process. Does not return.
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// An exited process remains in the zombie state
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// until its parent calls wait() to find out it exited.
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void exit(void) {
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struct proc *curproc = myproc();
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struct proc *p;
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int fd;
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if (curproc == initproc) {
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panic("init exiting");
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}
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// Close all open files.
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for (fd = 0; fd < NOFILE; fd++) {
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if (curproc->ofile[fd]) {
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fileclose(curproc->ofile[fd]);
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curproc->ofile[fd] = 0;
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}
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}
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begin_op();
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iput(curproc->cwd);
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end_op();
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curproc->cwd = 0;
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acquire(&ptable.lock);
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// Parent might be sleeping in wait().
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wakeup1(curproc->parent);
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// Pass abandoned children to init.
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for (p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
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if (p->parent == curproc) {
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p->parent = initproc;
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if (p->state == ZOMBIE) {
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wakeup1(initproc);
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}
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}
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}
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// Jump into the scheduler, never to return.
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curproc->state = ZOMBIE;
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sched();
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panic("zombie exit");
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}
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// Wait for a child process to exit and return its pid.
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// Return -1 if this process has no children.
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int wait(void) {
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struct proc *p;
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int havekids, pid;
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struct proc *curproc = myproc();
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acquire(&ptable.lock);
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for (;;) {
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// Scan through table looking for exited children.
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havekids = 0;
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for (p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
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if (p->parent != curproc) {
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continue;
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}
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havekids = 1;
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if (p->state == ZOMBIE) {
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// Found one.
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pid = p->pid;
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kfree(p->kstack);
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p->kstack = 0;
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freevm(p->pgdir);
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p->pid = 0;
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p->parent = 0;
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p->name[0] = 0;
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p->killed = 0;
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p->state = UNUSED;
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release(&ptable.lock);
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return pid;
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}
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}
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// No point waiting if we don't have any children.
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if (!havekids || curproc->killed) {
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release(&ptable.lock);
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return -1;
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}
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// Wait for children to exit. (See wakeup1 call in proc_exit.)
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sleep(curproc, &ptable.lock); //DOC: wait-sleep
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}
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}
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// Per-CPU process scheduler.
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// Each CPU calls scheduler() after setting itself up.
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// Scheduler never returns. It loops, doing:
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// - choose a process to run
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// - swtch to start running that process
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// - eventually that process transfers control
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// via swtch back to the scheduler.
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void scheduler(void) {
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struct proc *p;
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struct cpu *c = mycpu();
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c->proc = 0;
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for (;;) {
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// Enable interrupts on this processor.
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sti();
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// Loop over process table looking for process to run.
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acquire(&ptable.lock);
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for (p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
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if (p->state != RUNNABLE) {
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continue;
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}
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// Switch to chosen process. It is the process's job
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// to release ptable.lock and then reacquire it
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// before jumping back to us.
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c->proc = p;
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switchuvm(p);
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p->state = RUNNING;
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swtch(&(c->scheduler), p->context);
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switchkvm();
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// Process is done running for now.
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// It should have changed its p->state before coming back.
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c->proc = 0;
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}
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release(&ptable.lock);
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}
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}
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// Enter scheduler. Must hold only ptable.lock
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// and have changed proc->state. Saves and restores
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// intena because intena is a property of this
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// kernel thread, not this CPU. It should
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// be proc->intena and proc->ncli, but that would
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// break in the few places where a lock is held but
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// there's no process.
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void sched(void) {
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int intena;
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struct proc *p = myproc();
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if (!holding(&ptable.lock)) {
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panic("sched ptable.lock");
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}
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if (mycpu()->ncli != 1) {
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panic("sched locks");
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}
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if (p->state == RUNNING) {
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panic("sched running");
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}
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if (readeflags() & FL_IF) {
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panic("sched interruptible");
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}
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intena = mycpu()->intena;
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swtch(&p->context, mycpu()->scheduler);
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mycpu()->intena = intena;
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}
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// Give up the CPU for one scheduling round.
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void yield(void) {
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acquire(&ptable.lock); //DOC: yieldlock
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myproc()->state = RUNNABLE;
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sched();
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release(&ptable.lock);
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}
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// A fork child's very first scheduling by scheduler()
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// will swtch here. "Return" to user space.
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void forkret(void) {
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static int first = 1;
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// Still holding ptable.lock from scheduler.
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release(&ptable.lock);
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if (first) {
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// Some initialization functions must be run in the context
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// of a regular process (e.g., they call sleep), and thus cannot
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// be run from main().
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first = 0;
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iinit(ROOTDEV);
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initlog(ROOTDEV);
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}
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// Return to "caller", actually trapret (see allocproc).
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}
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// Atomically release lock and sleep on chan.
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// Reacquires lock when awakened.
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void sleep(void *chan, struct spinlock *lk) {
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struct proc *p = myproc();
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if (p == 0) {
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panic("sleep");
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}
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if (lk == 0) {
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panic("sleep without lk");
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}
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// Must acquire ptable.lock in order to
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// change p->state and then call sched.
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// Once we hold ptable.lock, we can be
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// guaranteed that we won't miss any wakeup
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// (wakeup runs with ptable.lock locked),
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// so it's okay to release lk.
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if (lk != &ptable.lock) { //DOC: sleeplock0
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acquire(&ptable.lock); //DOC: sleeplock1
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release(lk);
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}
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// Go to sleep.
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p->chan = chan;
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p->state = SLEEPING;
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sched();
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// Tidy up.
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p->chan = 0;
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// Reacquire original lock.
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if (lk != &ptable.lock) { //DOC: sleeplock2
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release(&ptable.lock);
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acquire(lk);
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}
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}
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// Wake up all processes sleeping on chan.
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// The ptable lock must be held.
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static void wakeup1(void *chan) {
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struct proc *p;
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for (p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
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if (p->state == SLEEPING && p->chan == chan) {
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p->state = RUNNABLE;
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}
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}
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}
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// Wake up all processes sleeping on chan.
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void wakeup(void *chan) {
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acquire(&ptable.lock);
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wakeup1(chan);
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release(&ptable.lock);
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}
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// Kill the process with the given pid.
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// Process won't exit until it returns
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// to user space (see trap in trap.c).
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int kill(int pid) {
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struct proc *p;
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acquire(&ptable.lock);
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for (p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
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if (p->pid == pid) {
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p->killed = 1;
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// Wake process from sleep if necessary.
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if (p->state == SLEEPING) {
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p->state = RUNNABLE;
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}
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release(&ptable.lock);
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return 0;
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}
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}
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release(&ptable.lock);
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return -1;
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}
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// Print a process listing to console. For debugging.
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// Runs when user types ^P on console.
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// No lock to avoid wedging a stuck machine further.
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void procdump(void) {
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static char *states[] = {
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[UNUSED] "unused",
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[EMBRYO] "embryo",
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[SLEEPING] "sleep ",
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[RUNNABLE] "runble",
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[RUNNING] "run ",
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[ZOMBIE] "zombie"
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};
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int i;
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struct proc *p;
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char *state;
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uint pc[10];
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for (p = ptable.proc; p < &ptable.proc[NPROC]; p++) {
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if (p->state == UNUSED) {
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continue;
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}
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if (p->state >= 0 && p->state < NELEM(states) && states[p->state]) {
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state = states[p->state];
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}
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else {
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state = "???";
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}
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cprintf("%d %s %s", p->pid, state, p->name);
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if (p->state == SLEEPING) {
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getcallerpcs((uint*)p->context->ebp + 2, pc);
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for (i = 0; i < 10 && pc[i] != 0; i++) {
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cprintf(" %p", pc[i]);
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}
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}
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cprintf("\n");
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}
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}
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