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freebsd-dev/sys/compat/linux/linux_fork.c
Dmitry Chagin 81338031c4 Switch linuxulator to use the native 1:1 threads. 
The reasons:
1. Get rid of the stubs/quirks with process dethreading,
   process reparent when the process group leader exits and close
   to this problems on wait(), waitpid(), etc.
2. Reuse our kernel code instead of writing excessive thread
   managment routines in Linuxulator.

Implementation details:

1. The thread is created via kern_thr_new() in the clone() call with
   the CLONE_THREAD parameter. Thus, everything else is a process.
2. The test that the process has a threads is done via P_HADTHREADS
   bit p_flag of struct proc.
3. Per thread emulator state data structure is now located in the
   struct thread and freed in the thread_dtor() hook.
   Mandatory holdig of the p_mtx required when referencing emuldata
   from the other threads.
4. PID mangling has changed. Now Linux pid is the native tid
   and Linux tgid is the native pid, with the exception of the first
   thread in the process where tid and pid are one and the same.

Ugliness:

   In case when the Linux thread is the initial thread in the thread
   group thread id is equal to the process id. Glibc depends on this
   magic (assert in pthread_getattr_np.c). So for system calls that
   take thread id as a parameter we should use the special method
   to reference struct thread.

Differential Revision:	https://reviews.freebsd.org/D1039
2015-05-24 14:53:16 +00:00

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/*-
* 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("$FreeBSD$");
#include "opt_compat.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_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;
newtd->td_sigmask = td->td_sigmask;
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 */
}
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