metal-cos/sys/kern/thread.c

#include <stdbool.h>
#include <stdint.h>
#include <string.h>

#include <errno.h>
#include <sys/syscall.h>

#include <sys/kassert.h>
#include <sys/kconfig.h>
#include <sys/kdebug.h>
#include <sys/kmem.h>
#include <sys/ktime.h>
#include <sys/mp.h>
#include <sys/spinlock.h>
#include <sys/thread.h>

#include <machine/trap.h>
#include <machine/pmap.h>

// Special Kernel Process
Process *kernelProcess;

// Scheduler Queues
Spinlock schedLock;
ThreadQueue waitQueue;
ThreadQueue runnableQueue;
Thread *curProc[MAX_CPUS];

// Process List
Spinlock procLock;
uint64_t nextProcessID;
ProcessQueue processList;

// Memory Pools
Slab processSlab;
Slab threadSlab;

void Handle_GlobalInit();

void
Thread_Init()
{
    nextProcessID = 1;

    Slab_Init(&processSlab, "Process Objects", sizeof(Process), 16);
    Slab_Init(&threadSlab, "Thread Objects", sizeof(Thread), 16);

    Spinlock_Init(&procLock, "Process List Lock", SPINLOCK_TYPE_NORMAL);
    Spinlock_Init(&schedLock, "Scheduler Lock", SPINLOCK_TYPE_RECURSIVE);

    TAILQ_INIT(&waitQueue);
    TAILQ_INIT(&runnableQueue);
    TAILQ_INIT(&processList);

    Handle_GlobalInit();

    // Kernel Process
    kernelProcess = Process_Create(NULL, "kernel");

    // Create an thread object for current context
    Process *proc = Process_Create(NULL, "init");
    curProc[0] = Thread_Create(proc);
    curProc[0]->schedState = SCHED_STATE_RUNNING;
}

void
Thread_InitAP()
{
    Thread *apthr = Thread_Create(kernelProcess);

    apthr->schedState = SCHED_STATE_RUNNING;

    //PAlloc_Release((void *)thr->kstack);
    //thr->kstack = 0;

    curProc[CPU()] = apthr;
}

/*
 * Process
 */

Process *
Process_Create(Process *parent, const char *title)
{
    Process *proc = (Process *)Slab_Alloc(&processSlab);

    if (!proc)
	return NULL;

    memset(proc, 0, sizeof(*proc));

    proc->pid = nextProcessID++;
    proc->threads = 0;
    proc->refCount = 1;
    TAILQ_INIT(&proc->threadList);

    if (title) {
	strncpy((char *)&proc->title, title, PROCESS_TITLE_LENGTH);
    } else {
	proc->title[0] = '\0';
    }

    proc->space = PMap_NewAS();
    if (proc->space == NULL) {
	Slab_Free(&processSlab, proc);
	return NULL;
    }
    proc->ustackNext = MEM_USERSPACE_STKBASE;

    Spinlock_Init(&proc->lock, "Process Lock", SPINLOCK_TYPE_NORMAL);

    Semaphore_Init(&proc->zombieSemaphore, 0, "Zombie Semaphore");
    TAILQ_INIT(&proc->zombieQueue);

    Handle_Init(proc);

    proc->parent = parent;
    if (parent) {
	Spinlock_Lock(&parent->lock);
	TAILQ_INSERT_TAIL(&parent->childrenList, proc, siblingList);
	Spinlock_Unlock(&parent->lock);
    }
    TAILQ_INIT(&proc->childrenList);
    TAILQ_INIT(&proc->zombieProc);
    Semaphore_Init(&proc->zombieProcSemaphore, 0, "Zombie Process Semaphore");

    Spinlock_Lock(&procLock);
    TAILQ_INSERT_TAIL(&processList, proc, processList);
    Spinlock_Unlock(&procLock);

    return proc;
}

static void
Process_Destroy(Process *proc)
{
    Handle_Destroy(proc);

    Spinlock_Destroy(&proc->lock);
    Semaphore_Destroy(&proc->zombieSemaphore);
    Semaphore_Destroy(&proc->zombieProcSemaphore);
    PMap_DestroyAS(proc->space);

    // XXX: We need to promote zombie processes to our parent
    // XXX: Release the semaphore as well

    if (proc->parent) {
	Spinlock_Lock(&proc->parent->lock);
	TAILQ_REMOVE(&proc->parent->zombieProc, proc, siblingList);
	Spinlock_Unlock(&proc->parent->lock);
    }
    Spinlock_Lock(&procLock);
    TAILQ_REMOVE(&processList, proc, processList);
    Spinlock_Unlock(&procLock);

    Slab_Free(&processSlab, proc);
}

Process *
Process_Lookup(uint64_t pid)
{
    Process *p;
    Process *proc = NULL;

    Spinlock_Lock(&procLock);
    TAILQ_FOREACH(p, &processList, processList) {
	if (p->pid == pid) {
	    Process_Retain(p);
	    proc = p;
	    break;
	}
    }
    Spinlock_Unlock(&procLock);

    return proc;
}

void
Process_Retain(Process *proc)
{
    ASSERT(proc->refCount != 0);
    __sync_fetch_and_add(&proc->refCount, 1);
}

void
Process_Release(Process *proc)
{
    ASSERT(proc->refCount != 0);
    if (__sync_fetch_and_sub(&proc->refCount, 1) == 1) {
	Process_Destroy(proc);
    }
}

uint64_t
Process_Wait(Process *proc, uint64_t pid)
{
    Thread *thr;
    Thread *thr_temp;
    Process *p = NULL;
    uint64_t status;

    // XXX: Need to verify pid exists!

    while (1) {
	Semaphore_Acquire(&proc->zombieProcSemaphore);
	// XXX: Forced exit check!

	Spinlock_Lock(&proc->lock);
	p = TAILQ_FIRST(&proc->zombieProc);
	if (pid == 0 || p->pid == pid) {
	    TAILQ_REMOVE(&proc->zombieProc, p, siblingList);
	    Spinlock_Unlock(&proc->lock);
	    break;
	}
	Spinlock_Unlock(&proc->lock);

	Semaphore_Release(&proc->zombieProcSemaphore);
    }

    status = (p->pid << 16) | p->exitCode;

    // Release threads
    TAILQ_FOREACH_SAFE(thr, &p->zombieQueue, schedQueue, thr_temp) {
	Thread_Release(thr);
    }

    // Release process
    Process_Release(p);

    return status;
}

/*
 * Thread
 */

Thread *
Thread_Create(Process *proc)
{
    Thread *thr = (Thread *)Slab_Alloc(&threadSlab);

    if (!thr)
	return NULL;

    memset(thr, 0, sizeof(*thr));

    ASSERT(proc != NULL);

    thr->tid = proc->nextThreadID++;
    thr->kstack = (uintptr_t)PAlloc_AllocPage();
    if (thr->kstack == 0) {
	Slab_Free(&threadSlab, thr);
	return NULL;
    }

    Process_Retain(proc);

    Spinlock_Lock(&proc->lock);
    thr->proc = proc;
    proc->threads++;
    TAILQ_INSERT_TAIL(&proc->threadList, thr, threadList);
    thr->space = proc->space;
    thr->ustack = proc->ustackNext;
    proc->ustackNext += MEM_USERSPACE_STKLEN;
    Spinlock_Unlock(&proc->lock);

    thr->schedState = SCHED_STATE_NULL;
    thr->timerEvt = NULL;
    thr->refCount = 1;

    Thread_InitArch(thr);
    // Initialize queue

    return thr;
}

Thread *
Thread_KThreadCreate(void (*f)(void *), void *arg)
{
    Thread *thr = Thread_Create(kernelProcess);
    if (!thr)
	return NULL;

    Thread_SetupKThread(thr, f, (uintptr_t)arg, 0, 0);

    return thr;
}

Thread *
Thread_UThreadCreate(Thread *oldThr, uint64_t rip, uint64_t arg)
{
    Process *proc = oldThr->proc;
    Thread *thr = (Thread *)Slab_Alloc(&threadSlab);

    if (!thr)
	return NULL;

    memset(thr, 0, sizeof(*thr));

    thr->tid = proc->nextThreadID++;
    thr->kstack = (uintptr_t)PAlloc_AllocPage();
    if (thr->kstack == 0) {
	Slab_Free(&threadSlab, thr);
	return NULL;
    }

    thr->space = oldThr->space;
    thr->schedState = SCHED_STATE_NULL;
    thr->refCount = 1;

    Spinlock_Lock(&proc->lock);
    thr->ustack = proc->ustackNext;
    proc->ustackNext += MEM_USERSPACE_STKLEN;
    Spinlock_Unlock(&proc->lock);

    PMap_AllocMap(thr->space, thr->ustack, MEM_USERSPACE_STKLEN, PTE_W);
    // XXX: Check failure

    Thread_InitArch(thr);
    // Initialize queue

    Thread_SetupUThread(thr, rip, arg);

    Process_Retain(proc);

    Spinlock_Lock(&proc->lock);
    thr->proc = proc;
    // XXX: Process lock
    proc->threads++;
    TAILQ_INSERT_TAIL(&proc->threadList, thr, threadList);
    Spinlock_Unlock(&proc->lock);

    return thr;
}

static void
Thread_Destroy(Thread *thr)
{
    Process *proc = thr->proc;

    // Free userspace stack

    Spinlock_Lock(&proc->lock);
    proc->threads--;
    TAILQ_REMOVE(&proc->threadList, thr, threadList);
    Spinlock_Unlock(&proc->lock);

    // Free AS
    PAlloc_Release((void *)thr->kstack);
    Slab_Free(&threadSlab, thr);

    // Release process handle
    Process_Release(thr->proc);
}

Thread *
Thread_Lookup(Process *proc, uint64_t tid)
{
    Thread *t;
    Thread *thr = NULL;

    Spinlock_Lock(&proc->lock);
    TAILQ_FOREACH(t, &proc->threadList, threadList) {
	if (t->tid == tid) {
	    Thread_Retain(t);
	    thr = t;
	    break;
	}
    }
    Spinlock_Unlock(&proc->lock);

    return thr;
}

void
Thread_Retain(Thread *thr)
{
    ASSERT(thr->refCount != 0);
    __sync_fetch_and_add(&thr->refCount, 1);
}

void
Thread_Release(Thread *thr)
{
    ASSERT(thr->refCount != 0);
    if (__sync_fetch_and_sub(&thr->refCount, 1) == 1) {
	Thread_Destroy(thr);
    }
}

uint64_t
Thread_Wait(Thread *thr, uint64_t tid)
{
    Thread *t;
    uint64_t status;

    ASSERT(thr->proc != NULL);

    if (tid == 0) {
	t = TAILQ_FIRST(&thr->proc->zombieQueue);
	if (!t) {
	    return SYSCALL_PACK(EAGAIN, 0);
	}

	TAILQ_REMOVE(&thr->proc->zombieQueue, t, schedQueue);
	status = t->exitValue;
	Thread_Release(t);
	return SYSCALL_PACK(0, status);
    }

    TAILQ_FOREACH(t, &thr->proc->zombieQueue, schedQueue) {
	if (t->tid == tid) {
	    TAILQ_REMOVE(&thr->proc->zombieQueue, t, schedQueue);
	    status = t->exitValue;
	    Thread_Release(t);
	    return SYSCALL_PACK(0, status);
	}
    }

    return 0;
}

/*
 * Scheduler Functions
 */

Thread *
Sched_Current()
{
    Spinlock_Lock(&schedLock);

    Thread *thr = curProc[CPU()];
    Thread_Retain(thr);

    Spinlock_Unlock(&schedLock);

    return thr;
}

void
Sched_SetRunnable(Thread *thr)
{
    Spinlock_Lock(&schedLock);

    if (thr->schedState == SCHED_STATE_WAITING) {
	thr->waitTime += KTime_GetEpochNS() - thr->waitStart;
	thr->waitStart = 0;
	TAILQ_REMOVE(&waitQueue, thr, schedQueue);
    }
    thr->schedState = SCHED_STATE_RUNNABLE;
    TAILQ_INSERT_TAIL(&runnableQueue, thr, schedQueue);

    Spinlock_Unlock(&schedLock);
}

void
Sched_SetWaiting(Thread *thr)
{
    Spinlock_Lock(&schedLock);

    thr->schedState = SCHED_STATE_WAITING;
    TAILQ_INSERT_TAIL(&waitQueue, thr, schedQueue);
    thr->waitStart = KTime_GetEpochNS();

    Spinlock_Unlock(&schedLock);
}

void
Sched_SetZombie(Thread *thr)
{
    Process *proc = thr->proc;

    Spinlock_Lock(&schedLock);

    thr->schedState = SCHED_STATE_ZOMBIE;
    Spinlock_Lock(&proc->lock);
    TAILQ_INSERT_TAIL(&proc->zombieQueue, thr, schedQueue);
    Spinlock_Unlock(&proc->lock);

    if (proc->threads == 1) {
	// All processes have parents except 'init' and 'kernel'
	ASSERT(proc->parent != NULL);
	Spinlock_Lock(&proc->parent->lock);
	TAILQ_REMOVE(&proc->parent->childrenList, proc, siblingList);
	TAILQ_INSERT_TAIL(&proc->parent->zombieProc, proc, siblingList);
	Semaphore_Release(&proc->parent->zombieProcSemaphore);
	Spinlock_Unlock(&proc->parent->lock);
    }

    Spinlock_Unlock(&schedLock);
}

static void
Sched_Switch(Thread *oldthr, Thread *newthr)
{
    // Load AS
    PMap_LoadAS(newthr->space);

    Thread_SwitchArch(oldthr, newthr);
}

void
Sched_Scheduler()
{
    Thread *prev;
    Thread *next;

    Spinlock_Lock(&schedLock);

    // Select next thread
    next = TAILQ_FIRST(&runnableQueue);
    if (!next) {
	/*
	 * There may be no other runnable processes on this core.  This is a 
	 * good opportunity to migrate threads.  We should never hit this case 
	 * once the OS is up and running because of the idle threads, but just 
	 * in case we should assert that we never return to a zombie or waiting 
	 * thread.
	 */
	ASSERT(curProc[CPU()]->schedState == SCHED_STATE_RUNNING);
	Spinlock_Unlock(&schedLock);
	return;
    }
    TAILQ_REMOVE(&runnableQueue, next, schedQueue);

    prev = curProc[CPU()];
    curProc[CPU()] = next;
    next->schedState = SCHED_STATE_RUNNING;
    next->ctxSwitches++;

    if (prev->schedState == SCHED_STATE_RUNNING) {
	prev->schedState = SCHED_STATE_RUNNABLE;
	TAILQ_INSERT_TAIL(&runnableQueue, prev, schedQueue);
    }

    Sched_Switch(prev, next);

    Spinlock_Unlock(&schedLock);
}

extern TaskStateSegment64 TSS[MAX_CPUS];

void
ThreadKThreadEntry(TrapFrame *tf)
{
    TSS[CPU()].rsp0 = curProc[CPU()]->kstack + 4096;

    Spinlock_Unlock(&schedLock);

    Trap_Pop(tf);
}

/*
 * Debugging
 */

void
Process_Dump(Process *proc)
{
    kprintf("title      %s\n", proc->title);
    kprintf("pid        %llu\n", proc->pid);
    kprintf("space      %016llx\n", proc->space);
    kprintf("threads    %llu\n", proc->threads);
    kprintf("refCount   %d\n", proc->refCount);
    kprintf("nextFD     %llu\n", proc->nextFD);
}

void
Thread_Dump(Thread *thr)
{
    // Thread_DumpArch(thr)
    kprintf("space      %016llx\n", thr->space);
    kprintf("kstack     %016llx\n", thr->kstack);
    kprintf("tid        %llu\n", thr->tid);
    kprintf("refCount   %d\n", thr->refCount);
    kprintf("state      %d\n", thr->schedState);
    kprintf("ctxswtch   %llu\n", thr->ctxSwitches);
    kprintf("utime      %llu\n", thr->userTime);
    kprintf("ktime      %llu\n", thr->kernTime);
    kprintf("wtime      %llu\n", thr->waitTime);
    if (thr->proc) {
	Process_Dump(thr->proc);
    }
}

static void
Debug_Threads(int argc, const char *argv[])
{
    int c = CPU();
    Thread *thr;

    //Spinlock_Lock(&threadLock);

    kprintf("CPU %d\n", c);
    kprintf("Current Thread: %d(%016llx) %d\n",
	    curProc[c]->tid, curProc[c], curProc[c]->ctxSwitches);
    Thread_Dump(curProc[c]);
    TAILQ_FOREACH(thr, &runnableQueue, schedQueue)
    {
	kprintf("Runnable Thread: %d(%016llx) %d\n", thr->tid, thr, thr->ctxSwitches);
	Thread_Dump(thr);
    }
    TAILQ_FOREACH(thr, &waitQueue, schedQueue)
    {
	kprintf("Waiting Thread: %d(%016llx) %d\n", thr->tid, thr, thr->ctxSwitches);
	Thread_Dump(thr);
    }

    //Spinlock_Unlock(&threadLock);
}

REGISTER_DBGCMD(threads, "Display list of threads", Debug_Threads);

static void
Debug_Processes(int argc, const char *argv[])
{
    Process *proc;

    //Spinlock_Lock(&threadLock);

    TAILQ_FOREACH(proc, &processList, processList)
    {
	kprintf("Process: %d(%016llx)\n", proc->pid, proc);
	Process_Dump(proc);
    }

    //Spinlock_Unlock(&threadLock);
}

REGISTER_DBGCMD(processes, "Display list of processes", Debug_Processes);

static void
Debug_ThreadInfo(int argc, const char *argv[])
{
}

REGISTER_DBGCMD(threadinfo, "Display thread state", Debug_ThreadInfo);