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-rw-r--r--proc.c141
1 files changed, 82 insertions, 59 deletions
diff --git a/proc.c b/proc.c
index c86f88f..fd58dec 100644
--- a/proc.c
+++ b/proc.c
@@ -11,7 +11,7 @@ struct spinlock proc_table_lock;
struct proc proc[NPROC];
struct proc *curproc[NCPU];
-int next_pid = 1;
+int nextpid = 1;
extern void forkret(void);
extern void forkret1(struct trapframe*);
@@ -21,37 +21,27 @@ pinit(void)
initlock(&proc_table_lock, "proc_table");
}
-// Set up CPU's segment descriptors and task state for a
-// given process.
-// If p==0, set up for "idle" state for when scheduler()
-// is idling, not running any process.
-void
-setupsegs(struct proc *p)
+// 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 cpu *c = &cpus[cpu()];
-
- c->ts.ss0 = SEG_KDATA << 3;
- if(p){
- c->ts.esp0 = (uint)(p->kstack + KSTACKSIZE);
- } else {
- c->ts.esp0 = 0xffffffff;
- }
+ int i;
+ struct proc *p;
- c->gdt[0] = SEG_NULL;
- 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_TSS] = SEG16(STS_T32A, (uint)&c->ts, sizeof(c->ts)-1, 0);
- c->gdt[SEG_TSS].s = 0;
- if(p){
- c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, (uint)p->mem, p->sz-1, DPL_USER);
- c->gdt[SEG_UDATA] = SEG(STA_W, (uint)p->mem, p->sz-1, DPL_USER);
- } else {
- c->gdt[SEG_UCODE] = SEG_NULL;
- c->gdt[SEG_UDATA] = SEG_NULL;
+ acquire(&proc_table_lock);
+ for(i = 0; i < NPROC; i++){
+ p = &proc[i];
+ if(p->state == UNUSED){
+ p->state = EMBRYO;
+ p->pid = nextpid++;
+ release(&proc_table_lock);
+ return p;
+ }
}
-
- lgdt(c->gdt, sizeof c->gdt);
- ltr(SEG_TSS << 3);
+ release(&proc_table_lock);
+ return 0;
}
// Grow current process's memory by n bytes.
@@ -73,29 +63,41 @@ growproc(int n)
return cp->sz - n;
}
-// Look in the process table for an UNUSED proc.
-// If found, change state to EMBRYO and return it.
-// Otherwise return 0.
-struct proc*
-allocproc(void)
+// Set up CPU's segment descriptors and task state for a
+// given process.
+// If p==0, set up for "idle" state for when scheduler()
+// is idling, not running any process.
+void
+setupsegs(struct proc *p)
{
- int i;
- struct proc *p;
+ struct cpu *c = &cpus[cpu()];
- for(i = 0; i < NPROC; i++){
- p = &proc[i];
- if(p->state == UNUSED){
- p->state = EMBRYO;
- return p;
- }
+ c->ts.ss0 = SEG_KDATA << 3;
+ if(p)
+ c->ts.esp0 = (uint)(p->kstack + KSTACKSIZE);
+ else
+ c->ts.esp0 = 0xffffffff;
+
+ c->gdt[0] = SEG_NULL;
+ 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_TSS] = SEG16(STS_T32A, (uint)&c->ts, sizeof(c->ts)-1, 0);
+ c->gdt[SEG_TSS].s = 0;
+ if(p){
+ c->gdt[SEG_UCODE] = SEG(STA_X|STA_R, (uint)p->mem, p->sz-1, DPL_USER);
+ c->gdt[SEG_UDATA] = SEG(STA_W, (uint)p->mem, p->sz-1, DPL_USER);
+ } else {
+ c->gdt[SEG_UCODE] = SEG_NULL;
+ c->gdt[SEG_UDATA] = SEG_NULL;
}
- return 0;
+
+ lgdt(c->gdt, sizeof(c->gdt));
+ ltr(SEG_TSS << 3);
}
// Create a new process copying p as the parent.
-// Does not copy the kernel stack.
-// Instead, sets up stack to return as if from system call.
-// Caller must arrange for process to run (set state to RUNNABLE).
+// Sets up stack to return as if from system call.
+// Caller must set state of returned proc to RUNNABLE.
struct proc*
copyproc(struct proc *p)
{
@@ -103,13 +105,8 @@ copyproc(struct proc *p)
struct proc *np;
// Allocate process.
- acquire(&proc_table_lock);
- if((np = allocproc()) == 0){
- release(&proc_table_lock);
+ if((np = allocproc()) == 0)
return 0;
- }
- np->pid = next_pid++;
- release(&proc_table_lock);
// Allocate kernel stack.
if((np->kstack = kalloc(KSTACKSIZE)) == 0){
@@ -120,7 +117,7 @@ copyproc(struct proc *p)
if(p){ // Copy process state from p.
np->ppid = p->pid;
- memmove(np->tf, p->tf, sizeof *np->tf);
+ memmove(np->tf, p->tf, sizeof(*np->tf));
np->sz = p->sz;
if((np->mem = kalloc(np->sz)) == 0){
@@ -132,24 +129,49 @@ copyproc(struct proc *p)
memmove(np->mem, p->mem, np->sz);
for(i = 0; i < NOFILE; i++){
- np->ofile[i] = p->ofile[i];
- if(np->ofile[i])
+ if((np->ofile[i] = p->ofile[i]) != 0)
fileincref(np->ofile[i]);
}
- np->cwd = iincref(p->cwd);
+ np->cwd = idup(p->cwd);
}
// Set up new jmpbuf to start executing at forkret (see below).
- memset(&np->jmpbuf, 0, sizeof np->jmpbuf);
+ memset(&np->jmpbuf, 0, sizeof(np->jmpbuf));
np->jmpbuf.eip = (uint)forkret;
np->jmpbuf.esp = (uint)np->tf - 4;
// Clear %eax so that fork system call returns 0 in child.
np->tf->eax = 0;
-
return np;
}
+// Set up first user process.
+void
+userinit(void)
+{
+ struct proc *p;
+ extern uchar _binary_initcode_start[], _binary_initcode_size[];
+
+ p = copyproc(0);
+ p->sz = PAGE;
+ p->mem = kalloc(p->sz);
+ p->cwd = namei("/");
+ memset(&p->tf, 0, sizeof(p->tf));
+ p->tf->es = p->tf->ds = p->tf->ss = (SEG_UDATA << 3) | DPL_USER;
+ p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
+ p->tf->eflags = FL_IF;
+ p->tf->esp = p->sz;
+
+ // Push dummy return address to placate gcc.
+ p->tf->esp -= 4;
+ *(uint*)(p->mem + p->tf->esp) = 0xefefefef;
+
+ p->tf->eip = 0;
+ memmove(p->mem, _binary_initcode_start, (int)_binary_initcode_size);
+ safestrcpy(p->name, "initcode", sizeof(p->name));
+ p->state = RUNNABLE;
+}
+
//PAGEBREAK: 42
// Per-CPU process scheduler.
// Each CPU calls scheduler() after setting itself up.
@@ -269,6 +291,7 @@ sleep(void *chan, struct spinlock *lk)
}
}
+//PAGEBREAK!
// Wake up all processes sleeping on chan.
// Proc_table_lock must be held.
void
@@ -334,7 +357,7 @@ proc_exit(void)
}
}
- idecref(cp->cwd);
+ iput(cp->cwd);
cp->cwd = 0;
acquire(&proc_table_lock);
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