707 lines
15 KiB
C
707 lines
15 KiB
C
#include "types.h"
|
||
#include "param.h"
|
||
#include "memlayout.h"
|
||
#include "riscv.h"
|
||
#include "spinlock.h"
|
||
#include "proc.h"
|
||
#include "defs.h"
|
||
|
||
struct cpu cpus[NCPU];
|
||
|
||
struct proc proc[NPROC];
|
||
|
||
struct proc *initproc;
|
||
|
||
int nextpid = 1;
|
||
struct spinlock pid_lock;
|
||
|
||
extern void forkret(void);
|
||
static void freeproc(struct proc *p);
|
||
|
||
extern char trampoline[]; // trampoline.S
|
||
|
||
// helps ensure that wakeups of wait()ing
|
||
// parents are not lost. helps obey the
|
||
// memory model when using p->parent.
|
||
// must be acquired before any p->lock.
|
||
struct spinlock wait_lock;
|
||
|
||
// Allocate a page for each process's kernel stack.
|
||
// Map it high in memory, followed by an invalid
|
||
// guard page.
|
||
void
|
||
proc_mapstacks(pagetable_t kpgtbl)
|
||
{
|
||
struct proc *p;
|
||
|
||
for(p = proc; p < &proc[NPROC]; p++) {
|
||
char *pa = kalloc();
|
||
if(pa == 0)
|
||
panic("kalloc");
|
||
uint64 va = KSTACK((int) (p - proc));
|
||
kvmmap(kpgtbl, va, (uint64)pa, PGSIZE, PTE_R | PTE_W);
|
||
}
|
||
}
|
||
|
||
// initialize the proc table.
|
||
void
|
||
procinit(void)
|
||
{
|
||
struct proc *p;
|
||
|
||
initlock(&pid_lock, "nextpid");
|
||
initlock(&wait_lock, "wait_lock");
|
||
for(p = proc; p < &proc[NPROC]; p++) {
|
||
initlock(&p->lock, "proc");
|
||
p->state = UNUSED;
|
||
p->kstack = KSTACK((int) (p - proc));
|
||
}
|
||
}
|
||
|
||
// Must be called with interrupts disabled,
|
||
// to prevent race with process being moved
|
||
// to a different CPU.
|
||
int
|
||
cpuid()
|
||
{
|
||
int id = r_tp();
|
||
return id;
|
||
}
|
||
|
||
// Return this CPU's cpu struct.
|
||
// Interrupts must be disabled.
|
||
struct cpu*
|
||
mycpu(void)
|
||
{
|
||
int id = cpuid();
|
||
struct cpu *c = &cpus[id];
|
||
return c;
|
||
}
|
||
|
||
// Return the current struct proc *, or zero if none.
|
||
struct proc*
|
||
myproc(void)
|
||
{
|
||
push_off();
|
||
struct cpu *c = mycpu();
|
||
struct proc *p = c->proc;
|
||
pop_off();
|
||
return p;
|
||
}
|
||
|
||
int
|
||
allocpid()
|
||
{
|
||
int pid;
|
||
|
||
acquire(&pid_lock);
|
||
pid = nextpid;
|
||
nextpid = nextpid + 1;
|
||
release(&pid_lock);
|
||
|
||
return pid;
|
||
}
|
||
|
||
// Look in the process table for an UNUSED proc.
|
||
// If found, initialize state required to run in the kernel,
|
||
// and return with p->lock held.
|
||
// If there are no free procs, or a memory allocation fails, return 0.
|
||
static struct proc*
|
||
allocproc(void)
|
||
{
|
||
struct proc *p;
|
||
|
||
for(p = proc; p < &proc[NPROC]; p++) {
|
||
acquire(&p->lock);
|
||
if(p->state == UNUSED) {
|
||
goto found;
|
||
} else {
|
||
release(&p->lock);
|
||
}
|
||
}
|
||
return 0;
|
||
|
||
found:
|
||
p->pid = allocpid();
|
||
p->state = USED;
|
||
|
||
// Allocate a trapframe page.
|
||
if((p->trapframe = (struct trapframe *)kalloc()) == 0){
|
||
freeproc(p);
|
||
release(&p->lock);
|
||
return 0;
|
||
}
|
||
|
||
// 为进程分配 pre_trapframe 空间，分配失败则释放进程资源并返回 0
|
||
if((p->pre_trapframe = (struct trapframe *)kalloc()) == 0){
|
||
freeproc(p);
|
||
release(&p->lock);
|
||
return 0;
|
||
}
|
||
|
||
// An empty user page table.
|
||
p->pagetable = proc_pagetable(p);
|
||
if(p->pagetable == 0){
|
||
freeproc(p);
|
||
release(&p->lock);
|
||
return 0;
|
||
}
|
||
|
||
// Set up new context to start executing at forkret,
|
||
// which returns to user space.
|
||
memset(&p->context, 0, sizeof(p->context));
|
||
p->context.ra = (uint64)forkret;
|
||
p->context.sp = p->kstack + PGSIZE;
|
||
|
||
return p;
|
||
}
|
||
|
||
// free a proc structure and the data hanging from it,
|
||
// including user pages.
|
||
// p->lock must be held.
|
||
static void
|
||
freeproc(struct proc *p)
|
||
{
|
||
if(p->trapframe)
|
||
kfree((void*)p->trapframe);
|
||
p->trapframe = 0;
|
||
if(p->pagetable)
|
||
proc_freepagetable(p->pagetable, p->sz);
|
||
// 如果进程的 pre_trapframe 存在，则释放其占用的内存，并将指针置为 0，防止悬空指针。
|
||
if(p->pre_trapframe)
|
||
kfree((void*)p->pre_trapframe);
|
||
p->pre_trapframe = 0;
|
||
p->pagetable = 0;
|
||
p->sz = 0;
|
||
p->pid = 0;
|
||
p->parent = 0;
|
||
p->name[0] = 0;
|
||
p->chan = 0;
|
||
p->killed = 0;
|
||
p->xstate = 0;
|
||
p->state = UNUSED;
|
||
}
|
||
|
||
// Create a user page table for a given process, with no user memory,
|
||
// but with trampoline and trapframe pages.
|
||
pagetable_t
|
||
proc_pagetable(struct proc *p)
|
||
{
|
||
pagetable_t pagetable;
|
||
|
||
// An empty page table.
|
||
pagetable = uvmcreate();
|
||
if(pagetable == 0)
|
||
return 0;
|
||
|
||
// map the trampoline code (for system call return)
|
||
// at the highest user virtual address.
|
||
// only the supervisor uses it, on the way
|
||
// to/from user space, so not PTE_U.
|
||
if(mappages(pagetable, TRAMPOLINE, PGSIZE,
|
||
(uint64)trampoline, PTE_R | PTE_X) < 0){
|
||
uvmfree(pagetable, 0);
|
||
return 0;
|
||
}
|
||
|
||
// map the trapframe page just below the trampoline page, for
|
||
// trampoline.S.
|
||
if(mappages(pagetable, TRAPFRAME, PGSIZE,
|
||
(uint64)(p->trapframe), PTE_R | PTE_W) < 0){
|
||
uvmunmap(pagetable, TRAMPOLINE, 1, 0);
|
||
uvmfree(pagetable, 0);
|
||
return 0;
|
||
}
|
||
|
||
return pagetable;
|
||
}
|
||
|
||
// Free a process's page table, and free the
|
||
// physical memory it refers to.
|
||
void
|
||
proc_freepagetable(pagetable_t pagetable, uint64 sz)
|
||
{
|
||
uvmunmap(pagetable, TRAMPOLINE, 1, 0);
|
||
uvmunmap(pagetable, TRAPFRAME, 1, 0);
|
||
uvmfree(pagetable, sz);
|
||
}
|
||
|
||
// a user program that calls exec("/init")
|
||
// assembled from ../user/initcode.S
|
||
// od -t xC ../user/initcode
|
||
uchar initcode[] = {
|
||
0x17, 0x05, 0x00, 0x00, 0x13, 0x05, 0x45, 0x02,
|
||
0x97, 0x05, 0x00, 0x00, 0x93, 0x85, 0x35, 0x02,
|
||
0x93, 0x08, 0x70, 0x00, 0x73, 0x00, 0x00, 0x00,
|
||
0x93, 0x08, 0x20, 0x00, 0x73, 0x00, 0x00, 0x00,
|
||
0xef, 0xf0, 0x9f, 0xff, 0x2f, 0x69, 0x6e, 0x69,
|
||
0x74, 0x00, 0x00, 0x24, 0x00, 0x00, 0x00, 0x00,
|
||
0x00, 0x00, 0x00, 0x00
|
||
};
|
||
|
||
// Set up first user process.
|
||
void
|
||
userinit(void)
|
||
{
|
||
struct proc *p;
|
||
|
||
p = allocproc();
|
||
initproc = p;
|
||
|
||
// allocate one user page and copy initcode's instructions
|
||
// and data into it.
|
||
uvmfirst(p->pagetable, initcode, sizeof(initcode));
|
||
p->sz = PGSIZE;
|
||
|
||
// prepare for the very first "return" from kernel to user.
|
||
p->trapframe->epc = 0; // user program counter
|
||
p->trapframe->sp = PGSIZE; // user stack pointer
|
||
|
||
safestrcpy(p->name, "initcode", sizeof(p->name));
|
||
p->cwd = namei("/");
|
||
|
||
p->state = RUNNABLE;
|
||
|
||
release(&p->lock);
|
||
}
|
||
|
||
// Grow or shrink user memory by n bytes.
|
||
// Return 0 on success, -1 on failure.
|
||
int
|
||
growproc(int n)
|
||
{
|
||
uint64 sz;
|
||
struct proc *p = myproc();
|
||
|
||
sz = p->sz;
|
||
if(n > 0){
|
||
if((sz = uvmalloc(p->pagetable, sz, sz + n, PTE_W)) == 0) {
|
||
return -1;
|
||
}
|
||
} else if(n < 0){
|
||
sz = uvmdealloc(p->pagetable, sz, sz + n);
|
||
}
|
||
p->sz = sz;
|
||
return 0;
|
||
}
|
||
|
||
// Create a new process, copying the parent.
|
||
// Sets up child kernel stack to return as if from fork() system call.
|
||
int
|
||
fork(void)
|
||
{
|
||
int i, pid;
|
||
struct proc *np;
|
||
struct proc *p = myproc();
|
||
|
||
// Allocate process.
|
||
if((np = allocproc()) == 0){
|
||
return -1;
|
||
}
|
||
|
||
// Copy user memory from parent to child.
|
||
if(uvmcopy(p->pagetable, np->pagetable, p->sz) < 0){
|
||
freeproc(np);
|
||
release(&np->lock);
|
||
return -1;
|
||
}
|
||
np->sz = p->sz;
|
||
|
||
// copy saved user registers.
|
||
*(np->trapframe) = *(p->trapframe);
|
||
|
||
// Cause fork to return 0 in the child.
|
||
np->trapframe->a0 = 0;
|
||
|
||
// increment reference counts on open file descriptors.
|
||
for(i = 0; i < NOFILE; i++)
|
||
if(p->ofile[i])
|
||
np->ofile[i] = filedup(p->ofile[i]);
|
||
np->cwd = idup(p->cwd);
|
||
|
||
safestrcpy(np->name, p->name, sizeof(p->name));
|
||
|
||
pid = np->pid;
|
||
|
||
release(&np->lock);
|
||
|
||
acquire(&wait_lock);
|
||
np->parent = p;
|
||
release(&wait_lock);
|
||
|
||
acquire(&np->lock);
|
||
np->state = RUNNABLE;
|
||
release(&np->lock);
|
||
|
||
return pid;
|
||
}
|
||
|
||
// Pass p's abandoned children to init.
|
||
// Caller must hold wait_lock.
|
||
void
|
||
reparent(struct proc *p)
|
||
{
|
||
struct proc *pp;
|
||
|
||
for(pp = proc; pp < &proc[NPROC]; pp++){
|
||
if(pp->parent == p){
|
||
pp->parent = initproc;
|
||
wakeup(initproc);
|
||
}
|
||
}
|
||
}
|
||
|
||
// Exit the current process. Does not return.
|
||
// An exited process remains in the zombie state
|
||
// until its parent calls wait().
|
||
void
|
||
exit(int status)
|
||
{
|
||
struct proc *p = myproc();
|
||
|
||
if(p == initproc)
|
||
panic("init exiting");
|
||
|
||
// Close all open files.
|
||
for(int fd = 0; fd < NOFILE; fd++){
|
||
if(p->ofile[fd]){
|
||
struct file *f = p->ofile[fd];
|
||
fileclose(f);
|
||
p->ofile[fd] = 0;
|
||
}
|
||
}
|
||
|
||
begin_op();
|
||
iput(p->cwd);
|
||
end_op();
|
||
p->cwd = 0;
|
||
|
||
acquire(&wait_lock);
|
||
|
||
// Give any children to init.
|
||
reparent(p);
|
||
|
||
// Parent might be sleeping in wait().
|
||
wakeup(p->parent);
|
||
|
||
acquire(&p->lock);
|
||
|
||
p->xstate = status;
|
||
p->state = ZOMBIE;
|
||
|
||
release(&wait_lock);
|
||
|
||
// Jump into the scheduler, never to return.
|
||
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(uint64 addr)
|
||
{
|
||
struct proc *pp;
|
||
int havekids, pid;
|
||
struct proc *p = myproc();
|
||
|
||
acquire(&wait_lock);
|
||
|
||
for(;;){
|
||
// Scan through table looking for exited children.
|
||
havekids = 0;
|
||
for(pp = proc; pp < &proc[NPROC]; pp++){
|
||
if(pp->parent == p){
|
||
// make sure the child isn't still in exit() or swtch().
|
||
acquire(&pp->lock);
|
||
|
||
havekids = 1;
|
||
if(pp->state == ZOMBIE){
|
||
// Found one.
|
||
pid = pp->pid;
|
||
if(addr != 0 && copyout(p->pagetable, addr, (char *)&pp->xstate,
|
||
sizeof(pp->xstate)) < 0) {
|
||
release(&pp->lock);
|
||
release(&wait_lock);
|
||
return -1;
|
||
}
|
||
freeproc(pp);
|
||
release(&pp->lock);
|
||
release(&wait_lock);
|
||
return pid;
|
||
}
|
||
release(&pp->lock);
|
||
}
|
||
}
|
||
|
||
// No point waiting if we don't have any children.
|
||
if(!havekids || killed(p)){
|
||
release(&wait_lock);
|
||
return -1;
|
||
}
|
||
|
||
// Wait for a child to exit.
|
||
sleep(p, &wait_lock); //DOC: wait-sleep
|
||
}
|
||
}
|
||
|
||
// 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;
|
||
struct cpu *c = mycpu();
|
||
|
||
c->proc = 0;
|
||
for(;;){
|
||
// The most recent process to run may have had interrupts
|
||
// turned off; enable them to avoid a deadlock if all
|
||
// processes are waiting.
|
||
intr_on();
|
||
|
||
int found = 0;
|
||
for(p = proc; p < &proc[NPROC]; p++) {
|
||
acquire(&p->lock);
|
||
if(p->state == RUNNABLE) {
|
||
// Switch to chosen process. It is the process's job
|
||
// to release its lock and then reacquire it
|
||
// before jumping back to us.
|
||
p->state = RUNNING;
|
||
c->proc = p;
|
||
swtch(&c->context, &p->context);
|
||
|
||
// Process is done running for now.
|
||
// It should have changed its p->state before coming back.
|
||
c->proc = 0;
|
||
found = 1;
|
||
}
|
||
release(&p->lock);
|
||
}
|
||
if(found == 0) {
|
||
// nothing to run; stop running on this core until an interrupt.
|
||
intr_on();
|
||
asm volatile("wfi");
|
||
}
|
||
}
|
||
}
|
||
|
||
// Switch to scheduler. Must hold only p->lock
|
||
// and have changed proc->state. Saves and restores
|
||
// intena because intena is a property of this
|
||
// kernel thread, not this CPU. It should
|
||
// be proc->intena and proc->noff, but that would
|
||
// break in the few places where a lock is held but
|
||
// there's no process.
|
||
void
|
||
sched(void)
|
||
{
|
||
int intena;
|
||
struct proc *p = myproc();
|
||
|
||
if(!holding(&p->lock))
|
||
panic("sched p->lock");
|
||
if(mycpu()->noff != 1)
|
||
panic("sched locks");
|
||
if(p->state == RUNNING)
|
||
panic("sched running");
|
||
if(intr_get())
|
||
panic("sched interruptible");
|
||
|
||
intena = mycpu()->intena;
|
||
swtch(&p->context, &mycpu()->context);
|
||
mycpu()->intena = intena;
|
||
}
|
||
|
||
// Give up the CPU for one scheduling round.
|
||
void
|
||
yield(void)
|
||
{
|
||
struct proc *p = myproc();
|
||
acquire(&p->lock);
|
||
p->state = RUNNABLE;
|
||
sched();
|
||
release(&p->lock);
|
||
}
|
||
|
||
// A fork child's very first scheduling by scheduler()
|
||
// will swtch to forkret.
|
||
void
|
||
forkret(void)
|
||
{
|
||
static int first = 1;
|
||
|
||
// Still holding p->lock from scheduler.
|
||
release(&myproc()->lock);
|
||
|
||
if (first) {
|
||
// File system initialization must be run in the context of a
|
||
// regular process (e.g., because it calls sleep), and thus cannot
|
||
// be run from main().
|
||
fsinit(ROOTDEV);
|
||
|
||
first = 0;
|
||
// ensure other cores see first=0.
|
||
__sync_synchronize();
|
||
}
|
||
|
||
usertrapret();
|
||
}
|
||
|
||
// Atomically release lock and sleep on chan.
|
||
// Reacquires lock when awakened.
|
||
void
|
||
sleep(void *chan, struct spinlock *lk)
|
||
{
|
||
struct proc *p = myproc();
|
||
|
||
// Must acquire p->lock in order to
|
||
// change p->state and then call sched.
|
||
// Once we hold p->lock, we can be
|
||
// guaranteed that we won't miss any wakeup
|
||
// (wakeup locks p->lock),
|
||
// so it's okay to release lk.
|
||
|
||
acquire(&p->lock); //DOC: sleeplock1
|
||
release(lk);
|
||
|
||
// Go to sleep.
|
||
p->chan = chan;
|
||
p->state = SLEEPING;
|
||
|
||
sched();
|
||
|
||
// Tidy up.
|
||
p->chan = 0;
|
||
|
||
// Reacquire original lock.
|
||
release(&p->lock);
|
||
acquire(lk);
|
||
}
|
||
|
||
// Wake up all processes sleeping on chan.
|
||
// Must be called without any p->lock.
|
||
void
|
||
wakeup(void *chan)
|
||
{
|
||
struct proc *p;
|
||
|
||
for(p = proc; p < &proc[NPROC]; p++) {
|
||
if(p != myproc()){
|
||
acquire(&p->lock);
|
||
if(p->state == SLEEPING && p->chan == chan) {
|
||
p->state = RUNNABLE;
|
||
}
|
||
release(&p->lock);
|
||
}
|
||
}
|
||
}
|
||
|
||
// Kill the process with the given pid.
|
||
// The victim won't exit until it tries to return
|
||
// to user space (see usertrap() in trap.c).
|
||
int
|
||
kill(int pid)
|
||
{
|
||
struct proc *p;
|
||
|
||
for(p = proc; p < &proc[NPROC]; p++){
|
||
acquire(&p->lock);
|
||
if(p->pid == pid){
|
||
p->killed = 1;
|
||
if(p->state == SLEEPING){
|
||
// Wake process from sleep().
|
||
p->state = RUNNABLE;
|
||
}
|
||
release(&p->lock);
|
||
return 0;
|
||
}
|
||
release(&p->lock);
|
||
}
|
||
return -1;
|
||
}
|
||
|
||
void
|
||
setkilled(struct proc *p)
|
||
{
|
||
acquire(&p->lock);
|
||
p->killed = 1;
|
||
release(&p->lock);
|
||
}
|
||
|
||
int
|
||
killed(struct proc *p)
|
||
{
|
||
int k;
|
||
|
||
acquire(&p->lock);
|
||
k = p->killed;
|
||
release(&p->lock);
|
||
return k;
|
||
}
|
||
|
||
// Copy to either a user address, or kernel address,
|
||
// depending on usr_dst.
|
||
// Returns 0 on success, -1 on error.
|
||
int
|
||
either_copyout(int user_dst, uint64 dst, void *src, uint64 len)
|
||
{
|
||
struct proc *p = myproc();
|
||
if(user_dst){
|
||
return copyout(p->pagetable, dst, src, len);
|
||
} else {
|
||
memmove((char *)dst, src, len);
|
||
return 0;
|
||
}
|
||
}
|
||
|
||
// Copy from either a user address, or kernel address,
|
||
// depending on usr_src.
|
||
// Returns 0 on success, -1 on error.
|
||
int
|
||
either_copyin(void *dst, int user_src, uint64 src, uint64 len)
|
||
{
|
||
struct proc *p = myproc();
|
||
if(user_src){
|
||
return copyin(p->pagetable, dst, src, len);
|
||
} else {
|
||
memmove(dst, (char*)src, len);
|
||
return 0;
|
||
}
|
||
}
|
||
|
||
// 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",
|
||
[USED] "used",
|
||
[SLEEPING] "sleep ",
|
||
[RUNNABLE] "runble",
|
||
[RUNNING] "run ",
|
||
[ZOMBIE] "zombie"
|
||
};
|
||
struct proc *p;
|
||
char *state;
|
||
|
||
printf("\n");
|
||
for(p = proc; p < &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 = "???";
|
||
printf("%d %s %s", p->pid, state, p->name);
|
||
printf("\n");
|
||
}
|
||
}
|