eaea18cb9c
Various changes made while offline. + bwrite sector argument is redundant; use b->sector. + reformatting of files for nicer PDF page breaks + distinguish between locked, unlocked inodes in type signatures + change FD_FILE to FD_INODE + move userinit (nee proc0init) to proc.c + move ROOTDEV to param.h + always parenthesize sizeof argument
464 lines
10 KiB
C
464 lines
10 KiB
C
#include "types.h"
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#include "mmu.h"
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#include "x86.h"
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#include "param.h"
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#include "file.h"
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#include "proc.h"
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#include "defs.h"
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#include "spinlock.h"
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struct spinlock proc_table_lock;
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struct proc proc[NPROC];
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struct proc *curproc[NCPU];
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int nextpid = 1;
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extern void forkret(void);
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extern void forkret1(struct trapframe*);
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void
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pinit(void)
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{
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initlock(&proc_table_lock, "proc_table");
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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 return it.
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// Otherwise return 0.
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static struct proc*
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allocproc(void)
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{
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int i;
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struct proc *p;
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acquire(&proc_table_lock);
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for(i = 0; i < NPROC; i++){
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p = &proc[i];
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if(p->state == UNUSED){
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p->state = EMBRYO;
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p->pid = nextpid++;
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release(&proc_table_lock);
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return p;
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}
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}
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release(&proc_table_lock);
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return 0;
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}
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// Grow current process's memory by n bytes.
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// Return old size on success, -1 on failure.
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int
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growproc(int n)
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{
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char *newmem, *oldmem;
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newmem = kalloc(cp->sz + n);
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if(newmem == 0)
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return 0xffffffff;
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memmove(newmem, cp->mem, cp->sz);
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memset(newmem + cp->sz, 0, n);
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oldmem = cp->mem;
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cp->mem = newmem;
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kfree(oldmem, cp->sz);
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cp->sz += n;
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return cp->sz - n;
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}
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// Set up CPU's segment descriptors and task state for a
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// given process.
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// If p==0, set up for "idle" state for when scheduler()
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// is idling, not running any process.
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void
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setupsegs(struct proc *p)
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{
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struct cpu *c = &cpus[cpu()];
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c->ts.ss0 = SEG_KDATA << 3;
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if(p)
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c->ts.esp0 = (uint)(p->kstack + KSTACKSIZE);
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else
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c->ts.esp0 = 0xffffffff;
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c->gdt[0] = SEG_NULL;
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c->gdt[SEG_KCODE] = SEG(STA_X|STA_R, 0, 0x100000 + 64*1024-1, 0);
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c->gdt[SEG_KDATA] = SEG(STA_W, 0, 0xffffffff, 0);
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c->gdt[SEG_TSS] = SEG16(STS_T32A, (uint)&c->ts, sizeof(c->ts)-1, 0);
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c->gdt[SEG_TSS].s = 0;
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if(p){
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c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, (uint)p->mem, p->sz-1, DPL_USER);
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c->gdt[SEG_UDATA] = SEG(STA_W, (uint)p->mem, p->sz-1, DPL_USER);
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} else {
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c->gdt[SEG_UCODE] = SEG_NULL;
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c->gdt[SEG_UDATA] = SEG_NULL;
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}
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lgdt(c->gdt, sizeof(c->gdt));
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ltr(SEG_TSS << 3);
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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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struct proc*
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copyproc(struct proc *p)
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{
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int i;
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struct proc *np;
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// Allocate process.
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if((np = allocproc()) == 0)
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return 0;
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// Allocate kernel stack.
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if((np->kstack = kalloc(KSTACKSIZE)) == 0){
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np->state = UNUSED;
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return 0;
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}
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np->tf = (struct trapframe*)(np->kstack + KSTACKSIZE) - 1;
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if(p){ // Copy process state from p.
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np->ppid = p->pid;
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memmove(np->tf, p->tf, sizeof(*np->tf));
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np->sz = p->sz;
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if((np->mem = kalloc(np->sz)) == 0){
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kfree(np->kstack, KSTACKSIZE);
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np->kstack = 0;
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np->state = UNUSED;
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return 0;
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}
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memmove(np->mem, p->mem, np->sz);
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for(i = 0; i < NOFILE; i++){
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if((np->ofile[i] = p->ofile[i]) != 0)
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fileincref(np->ofile[i]);
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}
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np->cwd = idup(p->cwd);
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}
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// Set up new jmpbuf to start executing at forkret (see below).
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memset(&np->jmpbuf, 0, sizeof(np->jmpbuf));
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np->jmpbuf.eip = (uint)forkret;
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np->jmpbuf.esp = (uint)np->tf - 4;
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// Clear %eax so that fork system call returns 0 in child.
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np->tf->eax = 0;
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return np;
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}
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// Set up first user process.
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void
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userinit(void)
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{
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struct proc *p;
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extern uchar _binary_initcode_start[], _binary_initcode_size[];
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p = copyproc(0);
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p->sz = PAGE;
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p->mem = kalloc(p->sz);
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p->cwd = namei("/");
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memset(&p->tf, 0, sizeof(p->tf));
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p->tf->es = p->tf->ds = p->tf->ss = (SEG_UDATA << 3) | DPL_USER;
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p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
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p->tf->eflags = FL_IF;
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p->tf->esp = p->sz;
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// Push dummy return address to placate gcc.
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p->tf->esp -= 4;
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*(uint*)(p->mem + p->tf->esp) = 0xefefefef;
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p->tf->eip = 0;
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memmove(p->mem, _binary_initcode_start, (int)_binary_initcode_size);
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safestrcpy(p->name, "initcode", sizeof(p->name));
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p->state = RUNNABLE;
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}
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//PAGEBREAK: 42
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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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// - longjmp to start running that process
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// - eventually that process transfers control back
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// via longjmp back to the scheduler.
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void
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scheduler(void)
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{
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struct proc *p;
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int i;
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for(;;){
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// Loop over process table looking for process to run.
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acquire(&proc_table_lock);
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for(i = 0; i < NPROC; i++){
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p = &proc[i];
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if(p->state != RUNNABLE)
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continue;
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// Switch to chosen process. It is the process's job
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// to release proc_table_lock and then reacquire it
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// before jumping back to us.
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setupsegs(p);
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cp = p;
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p->state = RUNNING;
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if(setjmp(&cpus[cpu()].jmpbuf) == 0)
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longjmp(&p->jmpbuf);
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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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cp = 0;
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setupsegs(0);
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}
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release(&proc_table_lock);
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}
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}
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// Enter scheduler. Must already hold proc_table_lock
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// and have changed curproc[cpu()]->state.
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void
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sched(void)
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{
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if(cp->state == RUNNING)
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panic("sched running");
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if(!holding(&proc_table_lock))
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panic("sched proc_table_lock");
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if(cpus[cpu()].nlock != 1)
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panic("sched locks");
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if(setjmp(&cp->jmpbuf) == 0)
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longjmp(&cpus[cpu()].jmpbuf);
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}
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// Give up the CPU for one scheduling round.
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void
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yield(void)
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{
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acquire(&proc_table_lock);
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cp->state = RUNNABLE;
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sched();
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release(&proc_table_lock);
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}
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// A fork child's very first scheduling by scheduler()
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// will longjmp here. "Return" to user space.
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void
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forkret(void)
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{
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// Still holding proc_table_lock from scheduler.
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release(&proc_table_lock);
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// Jump into assembly, never to return.
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forkret1(cp->tf);
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}
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// Atomically release lock and sleep on chan.
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// Reacquires lock when reawakened.
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void
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sleep(void *chan, struct spinlock *lk)
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{
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if(cp == 0)
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panic("sleep");
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if(lk == 0)
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panic("sleep without lk");
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// Must acquire proc_table_lock in order to
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// change p->state and then call sched.
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// Once we hold proc_table_lock, we can be
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// guaranteed that we won't miss any wakeup
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// (wakeup runs with proc_table_lock locked),
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// so it's okay to release lk.
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if(lk != &proc_table_lock){
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acquire(&proc_table_lock);
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release(lk);
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}
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// Go to sleep.
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cp->chan = chan;
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cp->state = SLEEPING;
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sched();
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// Tidy up.
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cp->chan = 0;
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// Reacquire original lock.
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if(lk != &proc_table_lock){
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release(&proc_table_lock);
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acquire(lk);
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}
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}
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//PAGEBREAK!
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// Wake up all processes sleeping on chan.
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// Proc_table_lock must be held.
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void
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wakeup1(void *chan)
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{
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struct proc *p;
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for(p = proc; p < &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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// Wake up all processes sleeping on chan.
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// Proc_table_lock is acquired and released.
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void
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wakeup(void *chan)
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{
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acquire(&proc_table_lock);
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wakeup1(chan);
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release(&proc_table_lock);
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}
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// Kill the process with the given pid.
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// Process won't actually exit until it returns
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// to user space (see trap in trap.c).
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int
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proc_kill(int pid)
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{
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struct proc *p;
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acquire(&proc_table_lock);
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for(p = proc; p < &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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release(&proc_table_lock);
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return 0;
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}
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}
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release(&proc_table_lock);
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return -1;
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}
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// Exit the current process. Does not return.
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// Exited processes remain in the zombie state
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// until their parent calls wait() to find out they exited.
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void
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proc_exit(void)
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{
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struct proc *p;
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int fd;
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if(cp->pid == 1)
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panic("init exiting");
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// Close all open files.
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for(fd = 0; fd < NOFILE; fd++){
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if(cp->ofile[fd]){
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fileclose(cp->ofile[fd]);
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cp->ofile[fd] = 0;
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}
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}
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iput(cp->cwd);
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cp->cwd = 0;
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acquire(&proc_table_lock);
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// Wake up our parent.
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for(p = proc; p < &proc[NPROC]; p++)
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if(p->pid == cp->ppid)
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wakeup1(p);
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// Reparent our children to process 1.
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for(p = proc; p < &proc[NPROC]; p++)
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if(p->ppid == cp->pid){
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p->ppid = 1;
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wakeup1(&proc[1]); // init
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}
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// Jump into the scheduler, never to return.
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cp->killed = 0;
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cp->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
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proc_wait(void)
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{
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struct proc *p;
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int i, havekids, pid;
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acquire(&proc_table_lock);
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for(;;){
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// Scan through table looking for zombie children.
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havekids = 0;
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for(i = 0; i < NPROC; i++){
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p = &proc[i];
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if(p->state == UNUSED)
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continue;
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if(p->ppid == cp->pid){
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if(p->state == ZOMBIE){
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// Found one.
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kfree(p->mem, p->sz);
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kfree(p->kstack, KSTACKSIZE);
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pid = p->pid;
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p->state = UNUSED;
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p->pid = 0;
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p->ppid = 0;
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p->name[0] = 0;
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release(&proc_table_lock);
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return pid;
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}
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havekids = 1;
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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 || cp->killed){
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release(&proc_table_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(cp, &proc_table_lock);
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}
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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
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procdump(void)
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{
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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, j;
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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(i = 0; i < NPROC; i++) {
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p = &proc[i];
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if(p->state == UNUSED)
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continue;
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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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else
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state = "???";
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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->jmpbuf.ebp+2, pc);
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for(j=0; j<10 && pc[j] != 0; j++)
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cprintf(" %p", pc[j]);
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}
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cprintf("\n");
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}
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}
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