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("$FreeBSD$");
   31 
   32 #include "opt_compat.h"
   33 #include "opt_kdtrace.h"
   34 
   35 #include <sys/param.h>
   36 #include <sys/systm.h>
   37 #include <sys/imgact.h>
   38 #include <sys/lock.h>
   39 #include <sys/mutex.h>
   40 #include <sys/proc.h>
   41 #include <sys/sched.h>
   42 #include <sys/sdt.h>
   43 #include <sys/sx.h>
   44 #include <sys/unistd.h>
   45 
   46 #ifdef COMPAT_LINUX32
   47 #include <machine/../linux32/linux.h>
   48 #include <machine/../linux32/linux32_proto.h>
   49 #else
   50 #include <machine/../linux/linux.h>
   51 #include <machine/../linux/linux_proto.h>
   52 #endif
   53 #include <compat/linux/linux_dtrace.h>
   54 #include <compat/linux/linux_signal.h>
   55 #include <compat/linux/linux_emul.h>
   56 
   57 /* DTrace init */
   58 LIN_SDT_PROVIDER_DECLARE(LINUX_DTRACE);
   59 
   60 /* Linuxulator-global DTrace probes */
   61 LIN_SDT_PROBE_DECLARE(locks, emul_lock, locked);
   62 LIN_SDT_PROBE_DECLARE(locks, emul_lock, unlock);
   63 
   64 
   65 int
   66 linux_fork(struct thread *td, struct linux_fork_args *args)
   67 {
   68         int error;
   69         struct proc *p2;
   70         struct thread *td2;
   71 
   72 #ifdef DEBUG
   73         if (ldebug(fork))
   74                 printf(ARGS(fork, ""));
   75 #endif
   76 
   77         if ((error = fork1(td, RFFDG | RFPROC | RFSTOPPED, 0, &p2, NULL, 0))
   78             != 0)
   79                 return (error);
   80 
   81         td->td_retval[0] = p2->p_pid;
   82         td->td_retval[1] = 0;
   83 
   84         error = linux_proc_init(td, td->td_retval[0], 0);
   85         if (error)
   86                 return (error);
   87 
   88         td2 = FIRST_THREAD_IN_PROC(p2);
   89 
   90         /*
   91          * Make this runnable after we are finished with it.
   92          */
   93         thread_lock(td2);
   94         TD_SET_CAN_RUN(td2);
   95         sched_add(td2, SRQ_BORING);
   96         thread_unlock(td2);
   97 
   98         return (0);
   99 }
  100 
  101 int
  102 linux_vfork(struct thread *td, struct linux_vfork_args *args)
  103 {
  104         int error;
  105         struct proc *p2;
  106         struct thread *td2;
  107 
  108 #ifdef DEBUG
  109         if (ldebug(vfork))
  110                 printf(ARGS(vfork, ""));
  111 #endif
  112 
  113         if ((error = fork1(td, RFFDG | RFPROC | RFMEM | RFPPWAIT | RFSTOPPED,
  114             0, &p2, NULL, 0)) != 0)
  115                 return (error);
  116 
  117         td->td_retval[0] = p2->p_pid;
  118 
  119         error = linux_proc_init(td, td->td_retval[0], 0);
  120         if (error)
  121                 return (error);
  122 
  123         td2 = FIRST_THREAD_IN_PROC(p2);
  124 
  125         /*
  126          * Make this runnable after we are finished with it.
  127          */
  128         thread_lock(td2);
  129         TD_SET_CAN_RUN(td2);
  130         sched_add(td2, SRQ_BORING);
  131         thread_unlock(td2);
  132 
  133         return (0);
  134 }
  135 
  136 int
  137 linux_clone(struct thread *td, struct linux_clone_args *args)
  138 {
  139         int error, ff = RFPROC | RFSTOPPED;
  140         struct proc *p2;
  141         struct thread *td2;
  142         int exit_signal;
  143         struct linux_emuldata *em;
  144 
  145 #ifdef DEBUG
  146         if (ldebug(clone)) {
  147                 printf(ARGS(clone, "flags %x, stack %p, parent tid: %p, "
  148                     "child tid: %p"), (unsigned)args->flags,
  149                     args->stack, args->parent_tidptr, args->child_tidptr);
  150         }
  151 #endif
  152 
  153         exit_signal = args->flags & 0x000000ff;
  154         if (LINUX_SIG_VALID(exit_signal)) {
  155                 if (exit_signal <= LINUX_SIGTBLSZ)
  156                         exit_signal =
  157                             linux_to_bsd_signal[_SIG_IDX(exit_signal)];
  158         } else if (exit_signal != 0)
  159                 return (EINVAL);
  160 
  161         if (args->flags & LINUX_CLONE_VM)
  162                 ff |= RFMEM;
  163         if (args->flags & LINUX_CLONE_SIGHAND)
  164                 ff |= RFSIGSHARE;
  165         /*
  166          * XXX: In Linux, sharing of fs info (chroot/cwd/umask)
  167          * and open files is independant.  In FreeBSD, its in one
  168          * structure but in reality it does not cause any problems
  169          * because both of these flags are usually set together.
  170          */
  171         if (!(args->flags & (LINUX_CLONE_FILES | LINUX_CLONE_FS)))
  172                 ff |= RFFDG;
  173 
  174         /*
  175          * Attempt to detect when linux_clone(2) is used for creating
  176          * kernel threads. Unfortunately despite the existence of the
  177          * CLONE_THREAD flag, version of linuxthreads package used in
  178          * most popular distros as of beginning of 2005 doesn't make
  179          * any use of it. Therefore, this detection relies on
  180          * empirical observation that linuxthreads sets certain
  181          * combination of flags, so that we can make more or less
  182          * precise detection and notify the FreeBSD kernel that several
  183          * processes are in fact part of the same threading group, so
  184          * that special treatment is necessary for signal delivery
  185          * between those processes and fd locking.
  186          */
  187         if ((args->flags & 0xffffff00) == LINUX_THREADING_FLAGS)
  188                 ff |= RFTHREAD;
  189 
  190         if (args->flags & LINUX_CLONE_PARENT_SETTID)
  191                 if (args->parent_tidptr == NULL)
  192                         return (EINVAL);
  193 
  194         if (args->flags & LINUX_CLONE_VFORK)
  195                 ff |= RFPPWAIT;
  196 
  197         error = fork1(td, ff, 0, &p2, NULL, 0);
  198         if (error)
  199                 return (error);
  200 
  201         if (args->flags & (LINUX_CLONE_PARENT | LINUX_CLONE_THREAD)) {
  202                 sx_xlock(&proctree_lock);
  203                 PROC_LOCK(p2);
  204                 proc_reparent(p2, td->td_proc->p_pptr);
  205                 PROC_UNLOCK(p2);
  206                 sx_xunlock(&proctree_lock);
  207         }
  208 
  209         /* create the emuldata */
  210         error = linux_proc_init(td, p2->p_pid, args->flags);
  211         /* reference it - no need to check this */
  212         em = em_find(p2, EMUL_DOLOCK);
  213         KASSERT(em != NULL, ("clone: emuldata not found."));
  214         /* and adjust it */
  215 
  216         if (args->flags & LINUX_CLONE_THREAD) {
  217 #ifdef notyet
  218                 PROC_LOCK(p2);
  219                 p2->p_pgrp = td->td_proc->p_pgrp;
  220                 PROC_UNLOCK(p2);
  221 #endif
  222                 exit_signal = 0;
  223         }
  224 
  225         if (args->flags & LINUX_CLONE_CHILD_SETTID)
  226                 em->child_set_tid = args->child_tidptr;
  227         else
  228                 em->child_set_tid = NULL;
  229 
  230         if (args->flags & LINUX_CLONE_CHILD_CLEARTID)
  231                 em->child_clear_tid = args->child_tidptr;
  232         else
  233                 em->child_clear_tid = NULL;
  234 
  235         EMUL_UNLOCK(&emul_lock);
  236 
  237         if (args->flags & LINUX_CLONE_PARENT_SETTID) {
  238                 error = copyout(&p2->p_pid, args->parent_tidptr,
  239                     sizeof(p2->p_pid));
  240                 if (error)
  241                         printf(LMSG("copyout failed!"));
  242         }
  243 
  244         PROC_LOCK(p2);
  245         p2->p_sigparent = exit_signal;
  246         PROC_UNLOCK(p2);
  247         td2 = FIRST_THREAD_IN_PROC(p2);
  248         /*
  249          * In a case of stack = NULL, we are supposed to COW calling process
  250          * stack. This is what normal fork() does, so we just keep tf_rsp arg
  251          * intact.
  252          */
  253         if (args->stack)
  254                 linux_set_upcall_kse(td2, PTROUT(args->stack));
  255 
  256         if (args->flags & LINUX_CLONE_SETTLS)
  257                 linux_set_cloned_tls(td2, args->tls);
  258 
  259 #ifdef DEBUG
  260         if (ldebug(clone))
  261                 printf(LMSG("clone: successful rfork to %d, "
  262                     "stack %p sig = %d"), (int)p2->p_pid, args->stack,
  263                     exit_signal);
  264 #endif
  265         /*
  266          * Make this runnable after we are finished with it.
  267          */
  268         thread_lock(td2);
  269         TD_SET_CAN_RUN(td2);
  270         sched_add(td2, SRQ_BORING);
  271         thread_unlock(td2);
  272 
  273         td->td_retval[0] = p2->p_pid;
  274         td->td_retval[1] = 0;
  275 
  276         return (0);
  277 }

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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