Esempio n. 1
0
/*
 * Implement fork's actions on an address space.
 * Here we arrange for the address space to be copied or referenced,
 * allocate a user struct (pcb and kernel stack), then call the
 * machine-dependent layer to fill those in and make the new process
 * ready to run.  The new process is set up so that it returns directly
 * to user mode to avoid stack copying and relocation problems.
 *
 * No requirements.
 */
void
vm_fork(struct proc *p1, struct proc *p2, int flags)
{
	if ((flags & RFPROC) == 0) {
		/*
		 * Divorce the memory, if it is shared, essentially
		 * this changes shared memory amongst threads, into
		 * COW locally.
		 */
		if ((flags & RFMEM) == 0) {
			if (p1->p_vmspace->vm_sysref.refcnt > 1) {
				vmspace_unshare(p1);
			}
		}
		cpu_fork(ONLY_LWP_IN_PROC(p1), NULL, flags);
		return;
	}

	if (flags & RFMEM) {
		vmspace_ref(p1->p_vmspace);
		p2->p_vmspace = p1->p_vmspace;
	}

	while (vm_page_count_severe()) {
		vm_wait(0);
	}

	if ((flags & RFMEM) == 0) {
		p2->p_vmspace = vmspace_fork(p1->p_vmspace);

		pmap_pinit2(vmspace_pmap(p2->p_vmspace));

		if (p1->p_vmspace->vm_shm)
			shmfork(p1, p2);
	}

	pmap_init_proc(p2);
}
Esempio n. 2
0
/*
 * forkproc
 *
 * Description:	Create a new process structure, given a parent process
 *		structure.
 *
 * Parameters:	parent_proc		The parent process
 *
 * Returns:	!NULL			The new process structure
 *		NULL			Error (insufficient free memory)
 *
 * Note:	When successful, the newly created process structure is
 *		partially initialized; if a caller needs to deconstruct the
 *		returned structure, they must call forkproc_free() to do so.
 */
proc_t
forkproc(proc_t parent_proc)
{
	proc_t child_proc;	/* Our new process */
	static int nextpid = 0, pidwrap = 0, nextpidversion = 0;
	int error = 0;
	struct session *sessp;
	uthread_t parent_uthread = (uthread_t)get_bsdthread_info(current_thread());

	MALLOC_ZONE(child_proc, proc_t , sizeof *child_proc, M_PROC, M_WAITOK);
	if (child_proc == NULL) {
		printf("forkproc: M_PROC zone exhausted\n");
		goto bad;
	}
	/* zero it out as we need to insert in hash */
	bzero(child_proc, sizeof *child_proc);

	MALLOC_ZONE(child_proc->p_stats, struct pstats *,
			sizeof *child_proc->p_stats, M_PSTATS, M_WAITOK);
	if (child_proc->p_stats == NULL) {
		printf("forkproc: M_SUBPROC zone exhausted (p_stats)\n");
		FREE_ZONE(child_proc, sizeof *child_proc, M_PROC);
		child_proc = NULL;
		goto bad;
	}
	MALLOC_ZONE(child_proc->p_sigacts, struct sigacts *,
			sizeof *child_proc->p_sigacts, M_SIGACTS, M_WAITOK);
	if (child_proc->p_sigacts == NULL) {
		printf("forkproc: M_SUBPROC zone exhausted (p_sigacts)\n");
		FREE_ZONE(child_proc->p_stats, sizeof *child_proc->p_stats, M_PSTATS);
		FREE_ZONE(child_proc, sizeof *child_proc, M_PROC);
		child_proc = NULL;
		goto bad;
	}

	/* allocate a callout for use by interval timers */
	child_proc->p_rcall = thread_call_allocate((thread_call_func_t)realitexpire, child_proc);
	if (child_proc->p_rcall == NULL) {
		FREE_ZONE(child_proc->p_sigacts, sizeof *child_proc->p_sigacts, M_SIGACTS);
		FREE_ZONE(child_proc->p_stats, sizeof *child_proc->p_stats, M_PSTATS);
		FREE_ZONE(child_proc, sizeof *child_proc, M_PROC);
		child_proc = NULL;
		goto bad;
	}


	/*
	 * Find an unused PID.  
	 */

	proc_list_lock();

	nextpid++;
retry:
	/*
	 * If the process ID prototype has wrapped around,
	 * restart somewhat above 0, as the low-numbered procs
	 * tend to include daemons that don't exit.
	 */
	if (nextpid >= PID_MAX) {
		nextpid = 100;
		pidwrap = 1;
	}
	if (pidwrap != 0) {

		/* if the pid stays in hash both for zombie and runniing state */
		if  (pfind_locked(nextpid) != PROC_NULL) {
			nextpid++;
			goto retry;
		}

		if (pgfind_internal(nextpid) != PGRP_NULL) {
			nextpid++;
			goto retry;
		}	
		if (session_find_internal(nextpid) != SESSION_NULL) {
			nextpid++;
			goto retry;
		}	
	}
	nprocs++;
	child_proc->p_pid = nextpid;
	child_proc->p_idversion = nextpidversion++;
#if 1
	if (child_proc->p_pid != 0) {
		if (pfind_locked(child_proc->p_pid) != PROC_NULL)
			panic("proc in the list already\n");
	}
#endif
	/* Insert in the hash */
	child_proc->p_listflag |= (P_LIST_INHASH | P_LIST_INCREATE);
	LIST_INSERT_HEAD(PIDHASH(child_proc->p_pid), child_proc, p_hash);
	proc_list_unlock();


	/*
	 * We've identified the PID we are going to use; initialize the new
	 * process structure.
	 */
	child_proc->p_stat = SIDL;
	child_proc->p_pgrpid = PGRPID_DEAD;

	/*
	 * The zero'ing of the proc was at the allocation time due to need
	 * for insertion to hash.  Copy the section that is to be copied
	 * directly from the parent.
	 */
	bcopy(&parent_proc->p_startcopy, &child_proc->p_startcopy,
	    (unsigned) ((caddr_t)&child_proc->p_endcopy - (caddr_t)&child_proc->p_startcopy));

	/*
	 * Some flags are inherited from the parent.
	 * Duplicate sub-structures as needed.
	 * Increase reference counts on shared objects.
	 * The p_stats and p_sigacts substructs are set in vm_fork.
	 */
	child_proc->p_flag = (parent_proc->p_flag & (P_LP64 | P_TRANSLATED | P_AFFINITY));
	if (parent_proc->p_flag & P_PROFIL)
		startprofclock(child_proc);
	/*
	 * Note that if the current thread has an assumed identity, this
	 * credential will be granted to the new process.
	 */
	child_proc->p_ucred = kauth_cred_get_with_ref();

#ifdef CONFIG_EMBEDDED
	lck_mtx_init(&child_proc->p_mlock, proc_lck_grp, proc_lck_attr);
	lck_mtx_init(&child_proc->p_fdmlock, proc_lck_grp, proc_lck_attr);
#if CONFIG_DTRACE
	lck_mtx_init(&child_proc->p_dtrace_sprlock, proc_lck_grp, proc_lck_attr);
#endif
	lck_spin_init(&child_proc->p_slock, proc_lck_grp, proc_lck_attr);
#else /* !CONFIG_EMBEDDED */
	lck_mtx_init(&child_proc->p_mlock, proc_mlock_grp, proc_lck_attr);
	lck_mtx_init(&child_proc->p_fdmlock, proc_fdmlock_grp, proc_lck_attr);
#if CONFIG_DTRACE
	lck_mtx_init(&child_proc->p_dtrace_sprlock, proc_lck_grp, proc_lck_attr);
#endif
	lck_spin_init(&child_proc->p_slock, proc_slock_grp, proc_lck_attr);
#endif /* !CONFIG_EMBEDDED */
	klist_init(&child_proc->p_klist);

	if (child_proc->p_textvp != NULLVP) {
		/* bump references to the text vnode */
		/* Need to hold iocount across the ref call */
		if (vnode_getwithref(child_proc->p_textvp) == 0) {
			error = vnode_ref(child_proc->p_textvp);
			vnode_put(child_proc->p_textvp);
			if (error != 0)
				child_proc->p_textvp = NULLVP;
		}
	}

	/*
	 * Copy the parents per process open file table to the child; if
	 * there is a per-thread current working directory, set the childs
	 * per-process current working directory to that instead of the
	 * parents.
	 *
	 * XXX may fail to copy descriptors to child
	 */
	child_proc->p_fd = fdcopy(parent_proc, parent_uthread->uu_cdir);

#if SYSV_SHM
	if (parent_proc->vm_shm) {
		/* XXX may fail to attach shm to child */
		(void)shmfork(parent_proc, child_proc);
	}
#endif
	/*
	 * inherit the limit structure to child
	 */
	proc_limitfork(parent_proc, child_proc);

	if (child_proc->p_limit->pl_rlimit[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
		uint64_t rlim_cur = child_proc->p_limit->pl_rlimit[RLIMIT_CPU].rlim_cur;
		child_proc->p_rlim_cpu.tv_sec = (rlim_cur > __INT_MAX__) ? __INT_MAX__ : rlim_cur;
	}

	/* Intialize new process stats, including start time */
	/* <rdar://6640543> non-zeroed portion contains garbage AFAICT */
	bzero(&child_proc->p_stats->pstat_startzero,
	    (unsigned) ((caddr_t)&child_proc->p_stats->pstat_endzero -
	    (caddr_t)&child_proc->p_stats->pstat_startzero));
	bzero(&child_proc->p_stats->user_p_prof, sizeof(struct user_uprof));
	microtime(&child_proc->p_start);
	child_proc->p_stats->p_start = child_proc->p_start;     /* for compat */

	if (parent_proc->p_sigacts != NULL)
		(void)memcpy(child_proc->p_sigacts,
				parent_proc->p_sigacts, sizeof *child_proc->p_sigacts);
	else
		(void)memset(child_proc->p_sigacts, 0, sizeof *child_proc->p_sigacts);

	sessp = proc_session(parent_proc);
	if (sessp->s_ttyvp != NULL && parent_proc->p_flag & P_CONTROLT)
		OSBitOrAtomic(P_CONTROLT, &child_proc->p_flag);
	session_rele(sessp);

	/*
	 * block all signals to reach the process.
	 * no transition race should be occuring with the child yet,
	 * but indicate that the process is in (the creation) transition.
	 */
	proc_signalstart(child_proc, 0);
	proc_transstart(child_proc, 0);

	child_proc->p_pcaction = (parent_proc->p_pcaction) & P_PCMAX;
	TAILQ_INIT(&child_proc->p_uthlist);
	TAILQ_INIT(&child_proc->p_aio_activeq);
	TAILQ_INIT(&child_proc->p_aio_doneq);

	/* Inherit the parent flags for code sign */
	child_proc->p_csflags = parent_proc->p_csflags;

	/*
	 * All processes have work queue locks; cleaned up by
	 * reap_child_locked()
	 */
	workqueue_init_lock(child_proc);

	/*
	 * Copy work queue information
	 *
	 * Note: This should probably only happen in the case where we are
	 *	creating a child that is a copy of the parent; since this
	 *	routine is called in the non-duplication case of vfork()
	 *	or posix_spawn(), then this information should likely not
	 *	be duplicated.
	 *
	 * <rdar://6640553> Work queue pointers that no longer point to code
	 */
	child_proc->p_wqthread = parent_proc->p_wqthread;
	child_proc->p_threadstart = parent_proc->p_threadstart;
	child_proc->p_pthsize = parent_proc->p_pthsize;
	child_proc->p_targconc = parent_proc->p_targconc;
	if ((parent_proc->p_lflag & P_LREGISTER) != 0) {
		child_proc->p_lflag |= P_LREGISTER;
	}
	child_proc->p_dispatchqueue_offset = parent_proc->p_dispatchqueue_offset;
#if PSYNCH
	pth_proc_hashinit(child_proc);
#endif /* PSYNCH */

#if CONFIG_LCTX
	child_proc->p_lctx = NULL;
	/* Add new process to login context (if any). */
	if (parent_proc->p_lctx != NULL) {
		/*
		 * <rdar://6640564> This should probably be delayed in the
		 * vfork() or posix_spawn() cases.
		 */
		LCTX_LOCK(parent_proc->p_lctx);
		enterlctx(child_proc, parent_proc->p_lctx, 0);
	}
#endif

bad:
	return(child_proc);
}