static void
racctd(void)
{
	struct thread *td;
	struct proc *p;
	struct timeval wallclock;
	uint64_t runtime;

	for (;;) {
		sx_slock(&allproc_lock);

		FOREACH_PROC_IN_SYSTEM(p) {
			if (p->p_state != PRS_NORMAL)
				continue;
			if (p->p_flag & P_SYSTEM)
				continue;

			microuptime(&wallclock);
			timevalsub(&wallclock, &p->p_stats->p_start);
			PROC_LOCK(p);
			PROC_SLOCK(p);
			FOREACH_THREAD_IN_PROC(p, td) {
				ruxagg(p, td);
				thread_lock(td);
				thread_unlock(td);
			}
			runtime = cputick2usec(p->p_rux.rux_runtime);
			PROC_SUNLOCK(p);
#ifdef notyet
			KASSERT(runtime >= p->p_prev_runtime,
			    ("runtime < p_prev_runtime"));
#else
			if (runtime < p->p_prev_runtime)
				runtime = p->p_prev_runtime;
#endif
			p->p_prev_runtime = runtime;
			mtx_lock(&racct_lock);
			racct_set_locked(p, RACCT_CPU, runtime);
			racct_set_locked(p, RACCT_WALLCLOCK,
			    wallclock.tv_sec * 1000000 + wallclock.tv_usec);
			mtx_unlock(&racct_lock);
			PROC_UNLOCK(p);
		}
		sx_sunlock(&allproc_lock);
		pause("-", hz);
	}

int
freebsd32_getcontext(struct thread *td, struct freebsd32_getcontext_args *uap)
{
	ucontext32_t uc;
	int ret;

	if (uap->ucp == NULL)
		ret = EINVAL;
	else {
		get_mcontext32(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
		PROC_LOCK(td->td_proc);
		uc.uc_sigmask = td->td_sigmask;
		PROC_UNLOCK(td->td_proc);
		ret = copyout(&uc, uap->ucp, UC32_COPY_SIZE);
	}
	return (ret);
}

/*
 * Get machine context.
 */
static int
ia32_get_mcontext(struct thread *td, struct ia32_mcontext *mcp, int flags)
{
	struct pcb *pcb;
	struct trapframe *tp;

	pcb = td->td_pcb;
	tp = td->td_frame;

	PROC_LOCK(curthread->td_proc);
	mcp->mc_onstack = sigonstack(tp->tf_rsp);
	PROC_UNLOCK(curthread->td_proc);
	/* Entry into kernel always sets TF_HASSEGS */
	mcp->mc_gs = tp->tf_gs;
	mcp->mc_fs = tp->tf_fs;
	mcp->mc_es = tp->tf_es;
	mcp->mc_ds = tp->tf_ds;
	mcp->mc_edi = tp->tf_rdi;
	mcp->mc_esi = tp->tf_rsi;
	mcp->mc_ebp = tp->tf_rbp;
	mcp->mc_isp = tp->tf_rsp;
	mcp->mc_eflags = tp->tf_rflags;
	if (flags & GET_MC_CLEAR_RET) {
		mcp->mc_eax = 0;
		mcp->mc_edx = 0;
		mcp->mc_eflags &= ~PSL_C;
	} else {
		mcp->mc_eax = tp->tf_rax;
		mcp->mc_edx = tp->tf_rdx;
	}
	mcp->mc_ebx = tp->tf_rbx;
	mcp->mc_ecx = tp->tf_rcx;
	mcp->mc_eip = tp->tf_rip;
	mcp->mc_cs = tp->tf_cs;
	mcp->mc_esp = tp->tf_rsp;
	mcp->mc_ss = tp->tf_ss;
	mcp->mc_len = sizeof(*mcp);
	mcp->mc_flags = tp->tf_flags;
	ia32_get_fpcontext(td, mcp, NULL, 0);
	mcp->mc_fsbase = pcb->pcb_fsbase;
	mcp->mc_gsbase = pcb->pcb_gsbase;
	mcp->mc_xfpustate = 0;
	mcp->mc_xfpustate_len = 0;
	bzero(mcp->mc_spare2, sizeof(mcp->mc_spare2));
	return (0);
}

int
freebsd32_getcontext(struct thread *td, struct freebsd32_getcontext_args *uap)
{
	struct ia32_ucontext uc;
	int ret;

	if (uap->ucp == NULL)
		ret = EINVAL;
	else {
		ia32_get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
		PROC_LOCK(td->td_proc);
		uc.uc_sigmask = td->td_sigmask;
		PROC_UNLOCK(td->td_proc);
		bzero(&uc.__spare__, sizeof(uc.__spare__));
		ret = copyout(&uc, uap->ucp, UC_COPY_SIZE);
	}
	return (ret);
}

/*
 * System call to enter capability mode for the process.
 */
int
sys_cap_enter(struct thread *td, struct cap_enter_args *uap)
{
	struct ucred *newcred, *oldcred;
	struct proc *p;

	if (IN_CAPABILITY_MODE(td))
		return (0);

	newcred = crget();
	p = td->td_proc;
	PROC_LOCK(p);
	oldcred = crcopysafe(p, newcred);
	newcred->cr_flags |= CRED_FLAG_CAPMODE;
	proc_set_cred(p, newcred);
	PROC_UNLOCK(p);
	crfree(oldcred);
	return (0);
}

static void
pagezero_start(void __unused *arg)
{
	int error;

	error = kthread_create(vm_pagezero, NULL, &pagezero_proc, RFSTOPPED, 0,
	    "pagezero");
	if (error)
		panic("pagezero_start: error %d\n", error);
	/*
	 * We're an idle task, don't count us in the load.
	 */
	PROC_LOCK(pagezero_proc);
	pagezero_proc->p_flag |= P_NOLOAD;
	PROC_UNLOCK(pagezero_proc);
	mtx_lock_spin(&sched_lock);
	setrunqueue(FIRST_THREAD_IN_PROC(pagezero_proc), SRQ_BORING);
	mtx_unlock_spin(&sched_lock);
}

/*
 * Called by events that want to shut down.. e.g  <CTL><ALT><DEL> on a PC
 */
void
shutdown_nice(int howto)
{

	if (initproc != NULL) {
		/* Send a signal to init(8) and have it shutdown the world. */
		PROC_LOCK(initproc);
		if (howto & RB_POWEROFF)
			kern_psignal(initproc, SIGUSR2);
		else if (howto & RB_HALT)
			kern_psignal(initproc, SIGUSR1);
		else
			kern_psignal(initproc, SIGINT);
		PROC_UNLOCK(initproc);
	} else {
		/* No init(8) running, so simply reboot. */
		kern_reboot(howto | RB_NOSYNC);
	}
}

void debugger_writemem_callback(struct allocation_t* ref)
{
	struct message_t* message = __get(ref);
	if (!message)
		return;

	if (message->header.request != 1)
		goto cleanup;

	if (message->socket < 0)
		goto cleanup;

	if (!message->payload)
		goto cleanup;

	struct debugger_writemem_t* request = (struct debugger_writemem_t*)message->payload;
	if (request->process_id < 0)
		goto cleanup;

	if (request->address == 0)
		goto cleanup;

	if (request->dataLength == 0)
		goto cleanup;

	struct  proc* (*pfind)(pid_t) = kdlsym(pfind);

	struct proc* process = pfind(request->process_id);
	if (process == 0)
		goto cleanup;

	void(*_mtx_unlock_flags)(struct mtx *m, int opts, const char *file, int line) = kdlsym(_mtx_unlock_flags);

	int result = proc_rw_mem(process, (void*)request->address, request->dataLength, request->data, &request->dataLength, 1);
	// You need to unlock the process, or the kernel will assert and hang
	PROC_UNLOCK(process);

	WriteLog(LL_Debug, "proc_rw_mem returned %d", result);


cleanup:
	__dec(ref);
}

static int
filemon_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag __unused,
    struct thread *td)
{
	int error = 0;
	struct filemon *filemon;
	struct proc *p;
#if __FreeBSD_version >= 900041
	cap_rights_t rights;
#endif

	devfs_get_cdevpriv((void **) &filemon);

	switch (cmd) {
	/* Set the output file descriptor. */
	case FILEMON_SET_FD:
		error = fget_write(td, *(int *)data,
#if __FreeBSD_version >= 900041
		    cap_rights_init(&rights, CAP_PWRITE),
#endif
		    &filemon->fp);
		if (error == 0)
			/* Write the file header. */
			filemon_comment(filemon);
		break;

	/* Set the monitored process ID. */
	case FILEMON_SET_PID:
		error = pget(*((pid_t *)data), PGET_CANDEBUG | PGET_NOTWEXIT,
		    &p);
		if (error == 0) {
			filemon->pid = p->p_pid;
			PROC_UNLOCK(p);
		}
		break;

	default:
		error = EINVAL;
		break;
	}

	return (error);
}

void
uhid_intr(usbd_xfer_handle xfer, usbd_private_handle addr, usbd_status status)
{
	struct uhid_softc *sc = addr;

#ifdef USB_DEBUG
	if (uhiddebug > 5) {
		u_int32_t cc, i;
		
		usbd_get_xfer_status(xfer, NULL, NULL, &cc, NULL);
		DPRINTF(("uhid_intr: status=%d cc=%d\n", status, cc));
		DPRINTF(("uhid_intr: data ="));
		for (i = 0; i < cc; i++)
			DPRINTF((" %02x", sc->sc_ibuf[i]));
		DPRINTF(("\n"));
	}
#endif

	if (status == USBD_CANCELLED)
		return;

	if (status != USBD_NORMAL_COMPLETION) {
		DPRINTF(("uhid_intr: status=%d\n", status));
		if (status == USBD_STALLED)
		    sc->sc_state |= UHID_NEEDCLEAR;
		return;
	}

	(void) b_to_q(sc->sc_ibuf, sc->sc_isize, &sc->sc_q);
		
	if (sc->sc_state & UHID_ASLP) {
		sc->sc_state &= ~UHID_ASLP;
		DPRINTFN(5, ("uhid_intr: waking %p\n", &sc->sc_q));
		wakeup(&sc->sc_q);
	}
	selwakeup(&sc->sc_rsel);
	if (sc->sc_async != NULL) {
		DPRINTFN(3, ("uhid_intr: sending SIGIO %p\n", sc->sc_async));
		PROC_LOCK(sc->sc_async);
		psignal(sc->sc_async, SIGIO);
		PROC_UNLOCK(sc->sc_async);
	}
}

int
pre_execve(struct thread *td, struct vmspace **oldvmspace)
{
	struct proc *p;
	int error;

	KASSERT(td == curthread, ("non-current thread %p", td));
	error = 0;
	p = td->td_proc;
	if ((p->p_flag & P_HADTHREADS) != 0) {
		PROC_LOCK(p);
		if (thread_single(p, SINGLE_BOUNDARY) != 0)
			error = ERESTART;
		PROC_UNLOCK(p);
	}
	KASSERT(error != 0 || (td->td_pflags & TDP_EXECVMSPC) == 0,
	    ("nested execve"));
	*oldvmspace = p->p_vmspace;
	return (error);
}

/*
 * Acquire the proc's p_filemon reference and lock the filemon.
 * The proc's p_filemon may not match this filemon on return.
 */
static struct filemon *
filemon_proc_get(struct proc *p)
{
	struct filemon *filemon;

	if (p->p_filemon == NULL)
		return (NULL);
	PROC_LOCK(p);
	filemon = filemon_acquire(p->p_filemon);
	PROC_UNLOCK(p);

	if (filemon == NULL)
		return (NULL);
	/*
	 * The p->p_filemon may have changed by now.  That case is handled
	 * by the exit and fork hooks and filemon_attach_proc specially.
	 */
	sx_xlock(&filemon->lock);
	return (filemon);
}

static int
soo_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
    int flags, struct thread *td)
{
	struct socket *so = fp->f_data;
	int error;

#ifdef MAC
	error = mac_socket_check_send(active_cred, so);
	if (error)
		return (error);
#endif
	error = sosend(so, 0, uio, 0, 0, 0, uio->uio_td);
	if (error == EPIPE && (so->so_options & SO_NOSIGPIPE) == 0) {
		PROC_LOCK(uio->uio_td->td_proc);
		tdsignal(uio->uio_td, SIGPIPE);
		PROC_UNLOCK(uio->uio_td->td_proc);
	}
	return (error);
}

/*
 * Filler function for proc/pid/self
 */
int
procfs_doprocfile(PFS_FILL_ARGS)
{
	char *fullpath;
	char *freepath;
	struct vnode *textvp;
	int error;

	freepath = NULL;
	PROC_LOCK(p);
	textvp = p->p_textvp;
	vhold(textvp);
	PROC_UNLOCK(p);
	error = vn_fullpath(td, textvp, &fullpath, &freepath);
	vdrop(textvp);
	if (error == 0)
		sbuf_printf(sb, "%s", fullpath);
	if (freepath != NULL)
		free(freepath, M_TEMP);
	return (error);
}

//2. Define syscall(struct thread *td, struct syscall_args *arg){...}
static int 
getProcessTickets(struct thread *td, struct getProcessTickets_args *arg)
{
    //getProcessTickets logic here
    //if PID exists, get tickets from such process
    //if PID does not exists, return error code (-1)
    struct proc *process1;
    int procTickets;
    process1 = pfind(arg->pid);
    if(process1 == NULL){
        td->td_retval[0] = -1;
        return 0;
    }
    else{
        procTickets = process1->tickets;
        td->td_retval[0] = procTickets;
        PROC_UNLOCK(process1);
        return 0;
    }
    
}

//2. Define syscall(struct thread *td, struct syscall_args *arg){...}
static int
setSocialInfo(struct thread *td, struct setSocialInfo_args *arg)
{
 
     //setSocialInfo logic:
     //if PID exists, set social_info to such process
     //if PID does not exists, return error code (-1)
    
    struct proc *process2;
    process2 = pfind(arg->pid);
    if(process2 == NULL){
        td->td_retval[0] = -1;
        return 0;
    }
    else{
        process2->social_info = arg->social_info; //set process's social_info with arg's social_info
        PROC_UNLOCK(process2);
        return 0;
    }
    
}

/* Remove and release the filemon on the given process. */
static void
filemon_proc_drop(struct proc *p)
{
	struct filemon *filemon;

	KASSERT(p->p_filemon != NULL, ("%s: proc %p NULL p_filemon",
	    __func__, p));
	sx_assert(&p->p_filemon->lock, SA_XLOCKED);
	PROC_LOCK(p);
	filemon = p->p_filemon;
	p->p_filemon = NULL;
	--filemon->proccnt;
	PROC_UNLOCK(p);
	/*
	 * This should not be the last reference yet.  filemon_release()
	 * cannot be called with filemon locked, which the caller expects
	 * will stay locked.
	 */
	KASSERT(filemon->refcnt > 1, ("%s: proc %p dropping filemon %p "
	    "with last reference", __func__, p, filemon));
	filemon_release(filemon);
}

int
setcontext(struct thread *td, struct setcontext_args *uap)
{
	ucontext_t uc;
	int ret;	

	if (uap->ucp == NULL)
		ret = EINVAL;
	else {
		ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
		if (ret == 0) {
			ret = set_mcontext(td, &uc.uc_mcontext);
			if (ret == 0) {
				SIG_CANTMASK(uc.uc_sigmask);
				PROC_LOCK(td->td_proc);
				td->td_sigmask = uc.uc_sigmask;
				PROC_UNLOCK(td->td_proc);
			}
		}
	}
	return (ret == 0 ? EJUSTRETURN : ret);
}

/* ARGSUSED */
int
sys_setloginclass(struct thread *td, struct setloginclass_args *uap)
{
	struct proc *p = td->td_proc;
	int error;
	char lcname[MAXLOGNAME];
	struct loginclass *newlc;
	struct ucred *newcred, *oldcred;

	error = priv_check(td, PRIV_PROC_SETLOGINCLASS);
	if (error != 0)
		return (error);
	error = copyinstr(uap->namebuf, lcname, sizeof(lcname), NULL);
	if (error != 0)
		return (error);

	newlc = loginclass_find(lcname);
	if (newlc == NULL)
		return (EINVAL);
	newcred = crget();

	PROC_LOCK(p);
	oldcred = crcopysafe(p, newcred);
	newcred->cr_loginclass = newlc;
	proc_set_cred(p, newcred);
#ifdef RACCT
	racct_proc_ucred_changed(p, oldcred, newcred);
	crhold(newcred);
#endif
	PROC_UNLOCK(p);
#ifdef RCTL
	rctl_proc_ucred_changed(p, newcred);
	crfree(newcred);
#endif
	loginclass_free(oldcred->cr_loginclass);
	crfree(oldcred);

	return (0);
}

int
sys_thr_exit(struct thread *td, struct thr_exit_args *uap)
    /* long *state */
{
	struct proc *p;

	p = td->td_proc;

	/* Signal userland that it can free the stack. */
	if ((void *)uap->state != NULL) {
		suword_lwpid(uap->state, 1);
		kern_umtx_wake(td, uap->state, INT_MAX, 0);
	}

	rw_wlock(&tidhash_lock);

	PROC_LOCK(p);

	if (p->p_numthreads != 1) {
		racct_sub(p, RACCT_NTHR, 1);
		LIST_REMOVE(td, td_hash);
		rw_wunlock(&tidhash_lock);
		tdsigcleanup(td);
		PROC_SLOCK(p);
		thread_stopped(p);
		thread_exit();
		/* NOTREACHED */
	}

	/*
	 * Ignore attempts to shut down last thread in the proc.  This
	 * will actually call _exit(2) in the usermode trampoline when
	 * it returns.
	 */
	PROC_UNLOCK(p);
	rw_wunlock(&tidhash_lock);
	return (0);
}