linux_fork.c

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    1 /*-
    2  * Copyright (c) 2004 Tim J. Robbins
    3  * Copyright (c) 2002 Doug Rabson
    4  * Copyright (c) 2000 Marcel Moolenaar
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer
   12  *    in this position and unchanged.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   25  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   27  */
   28 
   29 #include <sys/cdefs.h>
   30 __FBSDID("$FreeBSD: releng/9.1/sys/compat/linux/linux_fork.c 224987 2011-08-18 22:51:30Z jonathan $");
   31 
   32 #include "opt_compat.h"
   33 
   34 #include <sys/param.h>
   35 #include <sys/systm.h>
   36 #include <sys/imgact.h>
   37 #include <sys/lock.h>
   38 #include <sys/mutex.h>
   39 #include <sys/proc.h>
   40 #include <sys/sched.h>
   41 #include <sys/sx.h>
   42 #include <sys/unistd.h>
   43 
   44 #ifdef COMPAT_LINUX32
   45 #include <machine/../linux32/linux.h>
   46 #include <machine/../linux32/linux32_proto.h>
   47 #else
   48 #include <machine/../linux/linux.h>
   49 #include <machine/../linux/linux_proto.h>
   50 #endif
   51 #include <compat/linux/linux_signal.h>
   52 #include <compat/linux/linux_emul.h>
   53 
   54 
   55 int
   56 linux_fork(struct thread *td, struct linux_fork_args *args)
   57 {
   58         int error;
   59         struct proc *p2;
   60         struct thread *td2;
   61 
   62 #ifdef DEBUG
   63         if (ldebug(fork))
   64                 printf(ARGS(fork, ""));
   65 #endif
   66 
   67         if ((error = fork1(td, RFFDG | RFPROC | RFSTOPPED, 0, &p2, NULL, 0))
   68             != 0)
   69                 return (error);
   70 
   71         td->td_retval[0] = p2->p_pid;
   72         td->td_retval[1] = 0;
   73 
   74         error = linux_proc_init(td, td->td_retval[0], 0);
   75         if (error)
   76                 return (error);
   77 
   78         td2 = FIRST_THREAD_IN_PROC(p2);
   79 
   80         /*
   81          * Make this runnable after we are finished with it.
   82          */
   83         thread_lock(td2);
   84         TD_SET_CAN_RUN(td2);
   85         sched_add(td2, SRQ_BORING);
   86         thread_unlock(td2);
   87 
   88         return (0);
   89 }
   90 
   91 int
   92 linux_vfork(struct thread *td, struct linux_vfork_args *args)
   93 {
   94         int error;
   95         struct proc *p2;
   96         struct thread *td2;
   97 
   98 #ifdef DEBUG
   99         if (ldebug(vfork))
  100                 printf(ARGS(vfork, ""));
  101 #endif
  102 
  103         /* Exclude RFPPWAIT */
  104         if ((error = fork1(td, RFFDG | RFPROC | RFMEM | RFSTOPPED, 0, &p2,
  105             NULL, 0)) != 0)
  106                 return (error);
  107 
  108         td->td_retval[0] = p2->p_pid;
  109 
  110         error = linux_proc_init(td, td->td_retval[0], 0);
  111         if (error)
  112                 return (error);
  113 
  114         PROC_LOCK(p2);
  115         p2->p_flag |= P_PPWAIT;
  116         PROC_UNLOCK(p2);
  117 
  118         td2 = FIRST_THREAD_IN_PROC(p2);
  119 
  120         /*
  121          * Make this runnable after we are finished with it.
  122          */
  123         thread_lock(td2);
  124         TD_SET_CAN_RUN(td2);
  125         sched_add(td2, SRQ_BORING);
  126         thread_unlock(td2);
  127 
  128         /* wait for the children to exit, ie. emulate vfork */
  129         PROC_LOCK(p2);
  130         while (p2->p_flag & P_PPWAIT)
  131                 cv_wait(&p2->p_pwait, &p2->p_mtx);
  132         PROC_UNLOCK(p2);
  133 
  134         return (0);
  135 }
  136 
  137 int
  138 linux_clone(struct thread *td, struct linux_clone_args *args)
  139 {
  140         int error, ff = RFPROC | RFSTOPPED;
  141         struct proc *p2;
  142         struct thread *td2;
  143         int exit_signal;
  144         struct linux_emuldata *em;
  145 
  146 #ifdef DEBUG
  147         if (ldebug(clone)) {
  148                 printf(ARGS(clone, "flags %x, stack %p, parent tid: %p, "
  149                     "child tid: %p"), (unsigned)args->flags,
  150                     args->stack, args->parent_tidptr, args->child_tidptr);
  151         }
  152 #endif
  153 
  154         exit_signal = args->flags & 0x000000ff;
  155         if (LINUX_SIG_VALID(exit_signal)) {
  156                 if (exit_signal <= LINUX_SIGTBLSZ)
  157                         exit_signal =
  158                             linux_to_bsd_signal[_SIG_IDX(exit_signal)];
  159         } else if (exit_signal != 0)
  160                 return (EINVAL);
  161 
  162         if (args->flags & LINUX_CLONE_VM)
  163                 ff |= RFMEM;
  164         if (args->flags & LINUX_CLONE_SIGHAND)
  165                 ff |= RFSIGSHARE;
  166         /*
  167          * XXX: In Linux, sharing of fs info (chroot/cwd/umask)
  168          * and open files is independant.  In FreeBSD, its in one
  169          * structure but in reality it does not cause any problems
  170          * because both of these flags are usually set together.
  171          */
  172         if (!(args->flags & (LINUX_CLONE_FILES | LINUX_CLONE_FS)))
  173                 ff |= RFFDG;
  174 
  175         /*
  176          * Attempt to detect when linux_clone(2) is used for creating
  177          * kernel threads. Unfortunately despite the existence of the
  178          * CLONE_THREAD flag, version of linuxthreads package used in
  179          * most popular distros as of beginning of 2005 doesn't make
  180          * any use of it. Therefore, this detection relies on
  181          * empirical observation that linuxthreads sets certain
  182          * combination of flags, so that we can make more or less
  183          * precise detection and notify the FreeBSD kernel that several
  184          * processes are in fact part of the same threading group, so
  185          * that special treatment is necessary for signal delivery
  186          * between those processes and fd locking.
  187          */
  188         if ((args->flags & 0xffffff00) == LINUX_THREADING_FLAGS)
  189                 ff |= RFTHREAD;
  190 
  191         if (args->flags & LINUX_CLONE_PARENT_SETTID)
  192                 if (args->parent_tidptr == NULL)
  193                         return (EINVAL);
  194 
  195         error = fork1(td, ff, 0, &p2, NULL, 0);
  196         if (error)
  197                 return (error);
  198 
  199         if (args->flags & (LINUX_CLONE_PARENT | LINUX_CLONE_THREAD)) {
  200                 sx_xlock(&proctree_lock);
  201                 PROC_LOCK(p2);
  202                 proc_reparent(p2, td->td_proc->p_pptr);
  203                 PROC_UNLOCK(p2);
  204                 sx_xunlock(&proctree_lock);
  205         }
  206 
  207         /* create the emuldata */
  208         error = linux_proc_init(td, p2->p_pid, args->flags);
  209         /* reference it - no need to check this */
  210         em = em_find(p2, EMUL_DOLOCK);
  211         KASSERT(em != NULL, ("clone: emuldata not found."));
  212         /* and adjust it */
  213 
  214         if (args->flags & LINUX_CLONE_THREAD) {
  215 #ifdef notyet
  216                 PROC_LOCK(p2);
  217                 p2->p_pgrp = td->td_proc->p_pgrp;
  218                 PROC_UNLOCK(p2);
  219 #endif
  220                 exit_signal = 0;
  221         }
  222 
  223         if (args->flags & LINUX_CLONE_CHILD_SETTID)
  224                 em->child_set_tid = args->child_tidptr;
  225         else
  226                 em->child_set_tid = NULL;
  227 
  228         if (args->flags & LINUX_CLONE_CHILD_CLEARTID)
  229                 em->child_clear_tid = args->child_tidptr;
  230         else
  231                 em->child_clear_tid = NULL;
  232 
  233         EMUL_UNLOCK(&emul_lock);
  234 
  235         if (args->flags & LINUX_CLONE_PARENT_SETTID) {
  236                 error = copyout(&p2->p_pid, args->parent_tidptr,
  237                     sizeof(p2->p_pid));
  238                 if (error)
  239                         printf(LMSG("copyout failed!"));
  240         }
  241 
  242         PROC_LOCK(p2);
  243         p2->p_sigparent = exit_signal;
  244         PROC_UNLOCK(p2);
  245         td2 = FIRST_THREAD_IN_PROC(p2);
  246         /*
  247          * In a case of stack = NULL, we are supposed to COW calling process
  248          * stack. This is what normal fork() does, so we just keep tf_rsp arg
  249          * intact.
  250          */
  251         if (args->stack)
  252                 linux_set_upcall_kse(td2, PTROUT(args->stack));
  253 
  254         if (args->flags & LINUX_CLONE_SETTLS)
  255                 linux_set_cloned_tls(td2, args->tls);
  256 
  257 #ifdef DEBUG
  258         if (ldebug(clone))
  259                 printf(LMSG("clone: successful rfork to %d, "
  260                     "stack %p sig = %d"), (int)p2->p_pid, args->stack,
  261                     exit_signal);
  262 #endif
  263         if (args->flags & LINUX_CLONE_VFORK) {
  264                 PROC_LOCK(p2);
  265                 p2->p_flag |= P_PPWAIT;
  266                 PROC_UNLOCK(p2);
  267         }
  268 
  269         /*
  270          * Make this runnable after we are finished with it.
  271          */
  272         thread_lock(td2);
  273         TD_SET_CAN_RUN(td2);
  274         sched_add(td2, SRQ_BORING);
  275         thread_unlock(td2);
  276 
  277         td->td_retval[0] = p2->p_pid;
  278         td->td_retval[1] = 0;
  279 
  280         if (args->flags & LINUX_CLONE_VFORK) {
  281                 /* wait for the children to exit, ie. emulate vfork */
  282                 PROC_LOCK(p2);
  283                 while (p2->p_flag & P_PPWAIT)
  284                         cv_wait(&p2->p_pwait, &p2->p_mtx);
  285                 PROC_UNLOCK(p2);
  286         }
  287 
  288         return (0);
  289 }

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FreeBSD/Linux Kernel Cross Reference sys/compat/linux/linux_fork.c

FreeBSD/Linux Kernel Cross Reference
sys/compat/linux/linux_fork.c