compat/linux/linux_fork.c

/*-
 * Copyright (c) 2004 Tim J. Robbins
 * Copyright (c) 2002 Doug Rabson
 * Copyright (c) 2000 Marcel Moolenaar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer
 *    in this position and unchanged.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: stable/10/sys/compat/linux/linux_fork.c 293554 2016-01-09 16:58:03Z dchagin $");

#include "opt_compat.h"
#include "opt_kdtrace.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/imgact.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/racct.h>
#include <sys/sched.h>
#include <sys/syscallsubr.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/wait.h>

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>

#ifdef COMPAT_LINUX32
#include <machine/../linux32/linux.h>
#include <machine/../linux32/linux32_proto.h>
#else
#include <machine/../linux/linux.h>
#include <machine/../linux/linux_proto.h>
#endif
#include <compat/linux/linux_signal.h>
#include <compat/linux/linux_emul.h>
#include <compat/linux/linux_futex.h>
#include <compat/linux/linux_misc.h>
#include <compat/linux/linux_util.h>

int
linux_fork(struct thread *td, struct linux_fork_args *args)
{
	int error;
	struct proc *p2;
	struct thread *td2;

#ifdef DEBUG
	if (ldebug(fork))
		printf(ARGS(fork, ""));
#endif

	if ((error = fork1(td, RFFDG | RFPROC | RFSTOPPED, 0, &p2, NULL, 0))
	    != 0)
		return (error);

	td2 = FIRST_THREAD_IN_PROC(p2);

	linux_proc_init(td, td2, 0);

	td->td_retval[0] = p2->p_pid;

	/*
	 * Make this runnable after we are finished with it.
	 */
	thread_lock(td2);
	TD_SET_CAN_RUN(td2);
	sched_add(td2, SRQ_BORING);
	thread_unlock(td2);

	return (0);
}

int
linux_vfork(struct thread *td, struct linux_vfork_args *args)
{
	int error;
	struct proc *p2;
	struct thread *td2;

#ifdef DEBUG
	if (ldebug(vfork))
		printf(ARGS(vfork, ""));
#endif

	/* Exclude RFPPWAIT */
	if ((error = fork1(td, RFFDG | RFPROC | RFMEM | RFSTOPPED, 0, &p2,
	    NULL, 0)) != 0)
		return (error);


	td2 = FIRST_THREAD_IN_PROC(p2);

	linux_proc_init(td, td2, 0);

	PROC_LOCK(p2);
	p2->p_flag |= P_PPWAIT;
	PROC_UNLOCK(p2);

   	td->td_retval[0] = p2->p_pid;

	/*
	 * Make this runnable after we are finished with it.
	 */
	thread_lock(td2);
	TD_SET_CAN_RUN(td2);
	sched_add(td2, SRQ_BORING);
	thread_unlock(td2);

	/* wait for the children to exit, ie. emulate vfork */
	PROC_LOCK(p2);
	while (p2->p_flag & P_PPWAIT)
		cv_wait(&p2->p_pwait, &p2->p_mtx);
	PROC_UNLOCK(p2);

	return (0);
}

static int
linux_clone_proc(struct thread *td, struct linux_clone_args *args)
{
	int error, ff = RFPROC | RFSTOPPED;
	struct proc *p2;
	struct thread *td2;
	int exit_signal;
	struct linux_emuldata *em;

#ifdef DEBUG
	if (ldebug(clone)) {
		printf(ARGS(clone, "flags %x, stack %p, parent tid: %p, "
		    "child tid: %p"), (unsigned)args->flags,
		    args->stack, args->parent_tidptr, args->child_tidptr);
	}
#endif

	exit_signal = args->flags & 0x000000ff;
	if (LINUX_SIG_VALID(exit_signal)) {
		if (exit_signal <= LINUX_SIGTBLSZ)
			exit_signal =
			    linux_to_bsd_signal[_SIG_IDX(exit_signal)];
	} else if (exit_signal != 0)
		return (EINVAL);

	if (args->flags & LINUX_CLONE_VM)
		ff |= RFMEM;
	if (args->flags & LINUX_CLONE_SIGHAND)
		ff |= RFSIGSHARE;
	/*
	 * XXX: In Linux, sharing of fs info (chroot/cwd/umask)
	 * and open files is independant.  In FreeBSD, its in one
	 * structure but in reality it does not cause any problems
	 * because both of these flags are usually set together.
	 */
	if (!(args->flags & (LINUX_CLONE_FILES | LINUX_CLONE_FS)))
		ff |= RFFDG;

	if (args->flags & LINUX_CLONE_PARENT_SETTID)
		if (args->parent_tidptr == NULL)
			return (EINVAL);

	error = fork1(td, ff, 0, &p2, NULL, 0);
	if (error)
		return (error);

	td2 = FIRST_THREAD_IN_PROC(p2);

	/* create the emuldata */
	linux_proc_init(td, td2, args->flags);

	em = em_find(td2);
	KASSERT(em != NULL, ("clone_proc: emuldata not found.\n"));

	if (args->flags & LINUX_CLONE_CHILD_SETTID)
		em->child_set_tid = args->child_tidptr;
	else
	   	em->child_set_tid = NULL;

	if (args->flags & LINUX_CLONE_CHILD_CLEARTID)
		em->child_clear_tid = args->child_tidptr;
	else
	   	em->child_clear_tid = NULL;

	if (args->flags & LINUX_CLONE_PARENT_SETTID) {
		error = copyout(&p2->p_pid, args->parent_tidptr,
		    sizeof(p2->p_pid));
		if (error)
			printf(LMSG("copyout failed!"));
	}

	PROC_LOCK(p2);
	p2->p_sigparent = exit_signal;
	PROC_UNLOCK(p2);
	/*
	 * In a case of stack = NULL, we are supposed to COW calling process
	 * stack. This is what normal fork() does, so we just keep tf_rsp arg
	 * intact.
	 */
	linux_set_upcall_kse(td2, PTROUT(args->stack));

	if (args->flags & LINUX_CLONE_SETTLS)
		linux_set_cloned_tls(td2, args->tls);

#ifdef DEBUG
	if (ldebug(clone))
		printf(LMSG("clone: successful rfork to %d, "
		    "stack %p sig = %d"), (int)p2->p_pid, args->stack,
		    exit_signal);
#endif

	if (args->flags & LINUX_CLONE_VFORK) {
	   	PROC_LOCK(p2);
	   	p2->p_flag |= P_PPWAIT;
	   	PROC_UNLOCK(p2);
	}

	/*
	 * Make this runnable after we are finished with it.
	 */
	thread_lock(td2);
	TD_SET_CAN_RUN(td2);
	sched_add(td2, SRQ_BORING);
	thread_unlock(td2);

	td->td_retval[0] = p2->p_pid;

	if (args->flags & LINUX_CLONE_VFORK) {
		/* wait for the children to exit, ie. emulate vfork */
		PROC_LOCK(p2);
		while (p2->p_flag & P_PPWAIT)
			cv_wait(&p2->p_pwait, &p2->p_mtx);
		PROC_UNLOCK(p2);
	}

	return (0);
}

static int
linux_clone_thread(struct thread *td, struct linux_clone_args *args)
{
	struct linux_emuldata *em;
	struct thread *newtd;
	struct proc *p;
	int error;

#ifdef DEBUG
	if (ldebug(clone)) {
		printf(ARGS(clone, "thread: flags %x, stack %p, parent tid: %p, "
		    "child tid: %p"), (unsigned)args->flags,
		    args->stack, args->parent_tidptr, args->child_tidptr);
	}
#endif

	LINUX_CTR4(clone, "thread(%d) flags %x ptid %p ctid %p",
	    td->td_tid, (unsigned)args->flags,
	    args->parent_tidptr, args->child_tidptr);

	if (args->flags & LINUX_CLONE_PARENT_SETTID)
		if (args->parent_tidptr == NULL)
			return (EINVAL);

	/* Threads should be created with own stack */
	if (args->stack == NULL)
		return (EINVAL);

	p = td->td_proc;

	/* Initialize our td */
	error = kern_thr_alloc(p, 0, &newtd);
	if (error)
		return (error);

	cpu_set_upcall(newtd, td);

	bzero(&newtd->td_startzero,
	    __rangeof(struct thread, td_startzero, td_endzero));
	bcopy(&td->td_startcopy, &newtd->td_startcopy,
	    __rangeof(struct thread, td_startcopy, td_endcopy));

	newtd->td_proc = p;
	newtd->td_ucred = crhold(td->td_ucred);

	/* create the emuldata */
	linux_proc_init(td, newtd, args->flags);

	em = em_find(newtd);
	KASSERT(em != NULL, ("clone_thread: emuldata not found.\n"));

	if (args->flags & LINUX_CLONE_SETTLS)
		linux_set_cloned_tls(newtd, args->tls);

	if (args->flags & LINUX_CLONE_CHILD_SETTID)
		em->child_set_tid = args->child_tidptr;
	else
	   	em->child_set_tid = NULL;

	if (args->flags & LINUX_CLONE_CHILD_CLEARTID)
		em->child_clear_tid = args->child_tidptr;
	else
	   	em->child_clear_tid = NULL;

	cpu_thread_clean(newtd);

	linux_set_upcall_kse(newtd, PTROUT(args->stack));

	PROC_LOCK(p);
	p->p_flag |= P_HADTHREADS;
	bcopy(p->p_comm, newtd->td_name, sizeof(newtd->td_name));

	if (args->flags & LINUX_CLONE_PARENT)
		thread_link(newtd, p->p_pptr);
	else
		thread_link(newtd, p);

	thread_lock(td);
	/* let the scheduler know about these things. */
	sched_fork_thread(td, newtd);
	thread_unlock(td);
	if (P_SHOULDSTOP(p))
		newtd->td_flags |= TDF_ASTPENDING | TDF_NEEDSUSPCHK;
	PROC_UNLOCK(p);

	tidhash_add(newtd);

#ifdef DEBUG
	if (ldebug(clone))
		printf(ARGS(clone, "successful clone to %d, stack %p"),
		(int)newtd->td_tid, args->stack);
#endif

	LINUX_CTR2(clone, "thread(%d) successful clone to %d",
	    td->td_tid, newtd->td_tid);

	if (args->flags & LINUX_CLONE_PARENT_SETTID) {
		error = copyout(&newtd->td_tid, args->parent_tidptr,
		    sizeof(newtd->td_tid));
		if (error)
			printf(LMSG("clone_thread: copyout failed!"));
	}

	/*
	 * Make this runnable after we are finished with it.
	 */
	thread_lock(newtd);
	TD_SET_CAN_RUN(newtd);
	sched_add(newtd, SRQ_BORING);
	thread_unlock(newtd);

	td->td_retval[0] = newtd->td_tid;

	return (0);
}

int
linux_clone(struct thread *td, struct linux_clone_args *args)
{

	if (args->flags & LINUX_CLONE_THREAD)
		return (linux_clone_thread(td, args));
	else
		return (linux_clone_proc(td, args));
}

int
linux_exit(struct thread *td, struct linux_exit_args *args)
{
	struct linux_emuldata *em;

	em = em_find(td);
	KASSERT(em != NULL, ("exit: emuldata not found.\n"));

	LINUX_CTR2(exit, "thread(%d) (%d)", em->em_tid, args->rval);

	linux_thread_detach(td);

	/*
	 * XXX. When the last two threads of a process
	 * exit via pthread_exit() try thr_exit() first.
	 */
	kern_thr_exit(td);
	exit1(td, W_EXITCODE(args->rval, 0));
		/* NOTREACHED */
}

int
linux_set_tid_address(struct thread *td, struct linux_set_tid_address_args *args)
{
	struct linux_emuldata *em;

	em = em_find(td);
	KASSERT(em != NULL, ("set_tid_address: emuldata not found.\n"));

	em->child_clear_tid = args->tidptr;

	td->td_retval[0] = em->em_tid;

	LINUX_CTR3(set_tid_address, "tidptr(%d) %p, returns %d",
	    em->em_tid, args->tidptr, td->td_retval[0]);

	return (0);
}

void
linux_thread_detach(struct thread *td)
{
	struct linux_sys_futex_args cup;
	struct linux_emuldata *em;
	int *child_clear_tid;
	int error;

	em = em_find(td);
	KASSERT(em != NULL, ("thread_detach: emuldata not found.\n"));

	LINUX_CTR1(exit, "thread detach(%d)", em->em_tid);

	release_futexes(td, em);

	child_clear_tid = em->child_clear_tid;

	if (child_clear_tid != NULL) {

		LINUX_CTR2(exit, "thread detach(%d) %p",
		    em->em_tid, child_clear_tid);

		error = suword32(child_clear_tid, 0);
		if (error != 0)
			return;

		cup.uaddr = child_clear_tid;
		cup.op = LINUX_FUTEX_WAKE;
		cup.val = 1;		/* wake one */
		cup.timeout = NULL;
		cup.uaddr2 = NULL;
		cup.val3 = 0;
		error = linux_sys_futex(td, &cup);
		/*
		 * this cannot happen at the moment and if this happens it
		 * probably means there is a user space bug
		 */
		if (error != 0)
			linux_msg(td, "futex stuff in thread_detach failed.");
	}
}