linux_emul.c

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    1 /*-
    2  * Copyright (c) 2006 Roman Divacky
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer
   10  *    in this position and unchanged.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  * 3. The name of the author may not be used to endorse or promote products
   15  *    derived from this software without specific prior written permission
   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 
   34 #include <sys/param.h>
   35 #include <sys/systm.h>
   36 #include <sys/imgact.h>
   37 #include <sys/kernel.h>
   38 #include <sys/lock.h>
   39 #include <sys/malloc.h>
   40 #include <sys/mutex.h>
   41 #include <sys/sx.h>
   42 #include <sys/proc.h>
   43 #include <sys/syscallsubr.h>
   44 #include <sys/sysproto.h>
   45 #include <sys/unistd.h>
   46 
   47 #include <compat/linux/linux_emul.h>
   48 #include <compat/linux/linux_futex.h>
   49 
   50 #ifdef COMPAT_LINUX32
   51 #include <machine/../linux32/linux.h>
   52 #include <machine/../linux32/linux32_proto.h>
   53 #else
   54 #include <machine/../linux/linux.h>
   55 #include <machine/../linux/linux_proto.h>
   56 #endif
   57 
   58 struct sx       emul_shared_lock;
   59 struct mtx      emul_lock;
   60 
   61 /* this returns locked reference to the emuldata entry (if found) */
   62 struct linux_emuldata *
   63 em_find(struct proc *p, int locked)
   64 {
   65         struct linux_emuldata *em;
   66 
   67         if (locked == EMUL_DOLOCK)
   68                 EMUL_LOCK(&emul_lock);
   69 
   70         em = p->p_emuldata;
   71 
   72         if (em == NULL && locked == EMUL_DOLOCK)
   73                 EMUL_UNLOCK(&emul_lock);
   74 
   75         return (em);
   76 }
   77 
   78 int
   79 linux_proc_init(struct thread *td, pid_t child, int flags)
   80 {
   81         struct linux_emuldata *em, *p_em;
   82         struct proc *p;
   83 
   84         if (child != 0) {
   85                 /* non-exec call */
   86                 em = malloc(sizeof *em, M_LINUX, M_WAITOK | M_ZERO);
   87                 em->pid = child;
   88                 em->pdeath_signal = 0;
   89                 if (flags & LINUX_CLONE_THREAD) {
   90                         /* handled later in the code */
   91                 } else {
   92                         struct linux_emuldata_shared *s;
   93 
   94                         s = malloc(sizeof *s, M_LINUX, M_WAITOK | M_ZERO);
   95                         s->refs = 1;
   96                         s->group_pid = child;
   97 
   98                         LIST_INIT(&s->threads);
   99                         em->shared = s;
  100                 }
  101         } else {
  102                 /* lookup the old one */
  103                 em = em_find(td->td_proc, EMUL_DOLOCK);
  104                 KASSERT(em != NULL, ("proc_init: emuldata not found in exec case.\n"));
  105         }
  106 
  107         em->child_clear_tid = NULL;
  108         em->child_set_tid = NULL;
  109 
  110         /*
  111          * allocate the shared struct only in clone()/fork cases in the case
  112          * of clone() td = calling proc and child = pid of the newly created
  113          * proc
  114          */
  115         if (child != 0) {
  116                 if (flags & LINUX_CLONE_THREAD) {
  117                         /* lookup the parent */
  118                         /* 
  119                          * we dont have to lock the p_em because
  120                          * its waiting for us in linux_clone so
  121                          * there is no chance of it changing the
  122                          * p_em->shared address
  123                          */
  124                         p_em = em_find(td->td_proc, EMUL_DONTLOCK);
  125                         KASSERT(p_em != NULL, ("proc_init: parent emuldata not found for CLONE_THREAD\n"));
  126                         em->shared = p_em->shared;
  127                         EMUL_SHARED_WLOCK(&emul_shared_lock);
  128                         em->shared->refs++;
  129                         EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  130                 } else {
  131                         /*
  132                          * handled earlier to avoid malloc(M_WAITOK) with
  133                          * rwlock held
  134                          */
  135                 }
  136         }
  137         if (child != 0) {
  138                 EMUL_SHARED_WLOCK(&emul_shared_lock);
  139                 LIST_INSERT_HEAD(&em->shared->threads, em, threads);
  140                 EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  141 
  142                 p = pfind(child);
  143                 KASSERT(p != NULL, ("process not found in proc_init\n"));
  144                 p->p_emuldata = em;
  145                 PROC_UNLOCK(p);
  146         } else
  147                 EMUL_UNLOCK(&emul_lock);
  148 
  149         return (0);
  150 }
  151 
  152 void
  153 linux_proc_exit(void *arg __unused, struct proc *p)
  154 {
  155         struct linux_emuldata *em;
  156         int error;
  157         struct thread *td = FIRST_THREAD_IN_PROC(p);
  158         int *child_clear_tid;
  159         struct proc *q, *nq;
  160 
  161         if (__predict_true(p->p_sysent != &elf_linux_sysvec))
  162                 return;
  163 
  164         /* find the emuldata */
  165         em = em_find(p, EMUL_DOLOCK);
  166 
  167         KASSERT(em != NULL, ("proc_exit: emuldata not found.\n"));
  168 
  169         /* reparent all procs that are not a thread leader to initproc */
  170         if (em->shared->group_pid != p->p_pid) {
  171                 child_clear_tid = em->child_clear_tid;
  172                 EMUL_UNLOCK(&emul_lock);
  173                 sx_xlock(&proctree_lock);
  174                 wakeup(initproc);
  175                 PROC_LOCK(p);
  176                 proc_reparent(p, initproc);
  177                 p->p_sigparent = SIGCHLD;
  178                 PROC_UNLOCK(p);
  179                 sx_xunlock(&proctree_lock);
  180         } else {
  181                 child_clear_tid = em->child_clear_tid;
  182                 EMUL_UNLOCK(&emul_lock);        
  183         }
  184 
  185         EMUL_SHARED_WLOCK(&emul_shared_lock);
  186         LIST_REMOVE(em, threads);
  187 
  188         em->shared->refs--;
  189         if (em->shared->refs == 0) {
  190                 EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  191                 free(em->shared, M_LINUX);
  192         } else  
  193                 EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  194 
  195         if (child_clear_tid != NULL) {
  196                 struct linux_sys_futex_args cup;
  197                 int null = 0;
  198 
  199                 error = copyout(&null, child_clear_tid, sizeof(null));
  200                 if (error) {
  201                         free(em, M_LINUX);
  202                         return;
  203                 }
  204 
  205                 /* futexes stuff */
  206                 cup.uaddr = child_clear_tid;
  207                 cup.op = LINUX_FUTEX_WAKE;
  208                 cup.val = 0x7fffffff;   /* Awake everyone */
  209                 cup.timeout = NULL;
  210                 cup.uaddr2 = NULL;
  211                 cup.val3 = 0;
  212                 error = linux_sys_futex(FIRST_THREAD_IN_PROC(p), &cup);
  213                 /*
  214                  * this cannot happen at the moment and if this happens it
  215                  * probably means there is a user space bug
  216                  */
  217                 if (error)
  218                         printf(LMSG("futex stuff in proc_exit failed.\n"));
  219         }
  220 
  221         /* clean the stuff up */
  222         free(em, M_LINUX);
  223 
  224         /* this is a little weird but rewritten from exit1() */
  225         sx_xlock(&proctree_lock);
  226         q = LIST_FIRST(&p->p_children);
  227         for (; q != NULL; q = nq) {
  228                 nq = LIST_NEXT(q, p_sibling);
  229                 if (q->p_flag & P_WEXIT)
  230                         continue;
  231                 if (__predict_false(q->p_sysent != &elf_linux_sysvec))
  232                         continue;
  233                 em = em_find(q, EMUL_DOLOCK);
  234                 KASSERT(em != NULL, ("linux_reparent: emuldata not found: %i\n", q->p_pid));
  235                 PROC_LOCK(q);
  236                 if ((q->p_flag & P_WEXIT) == 0 && em->pdeath_signal != 0) {
  237                         psignal(q, em->pdeath_signal);
  238                 }
  239                 PROC_UNLOCK(q);
  240                 EMUL_UNLOCK(&emul_lock);
  241         }
  242         sx_xunlock(&proctree_lock);
  243 }
  244 
  245 /*
  246  * This is used in a case of transition from FreeBSD binary execing to linux binary
  247  * in this case we create linux emuldata proc entry with the pid of the currently running
  248  * process.
  249  */
  250 void 
  251 linux_proc_exec(void *arg __unused, struct proc *p, struct image_params *imgp)
  252 {
  253         if (__predict_false(imgp->sysent == &elf_linux_sysvec
  254             && p->p_sysent != &elf_linux_sysvec))
  255                 linux_proc_init(FIRST_THREAD_IN_PROC(p), p->p_pid, 0);
  256         if (__predict_false(imgp->sysent != &elf_linux_sysvec
  257             && p->p_sysent == &elf_linux_sysvec)) {
  258                 struct linux_emuldata *em;
  259 
  260                 /* 
  261                  * XXX:There's a race because here we assign p->p_emuldata NULL
  262                  * but the process is still counted as linux one for a short
  263                  * time so some other process might reference it and try to
  264                  * access its p->p_emuldata and panicing on a NULL reference.
  265                  */
  266                 em = em_find(p, EMUL_DONTLOCK);
  267 
  268                 KASSERT(em != NULL, ("proc_exec: emuldata not found.\n"));
  269 
  270                 EMUL_SHARED_WLOCK(&emul_shared_lock);
  271                 LIST_REMOVE(em, threads);
  272 
  273                 PROC_LOCK(p);
  274                 p->p_emuldata = NULL;
  275                 PROC_UNLOCK(p);
  276 
  277                 em->shared->refs--;
  278                 if (em->shared->refs == 0) {
  279                         EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  280                         free(em->shared, M_LINUX);
  281                 } else
  282                         EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  283 
  284                 free(em, M_LINUX);
  285         }
  286 }
  287 
  288 void
  289 linux_schedtail(void *arg __unused, struct proc *p)
  290 {
  291         struct linux_emuldata *em;
  292         int error = 0;
  293         int *child_set_tid;
  294 
  295         if (__predict_true(p->p_sysent != &elf_linux_sysvec))
  296                 return;
  297 
  298         /* find the emuldata */
  299         em = em_find(p, EMUL_DOLOCK);
  300 
  301         KASSERT(em != NULL, ("linux_schedtail: emuldata not found.\n"));
  302         child_set_tid = em->child_set_tid;
  303         EMUL_UNLOCK(&emul_lock);
  304 
  305         if (child_set_tid != NULL)
  306                 error = copyout(&p->p_pid, (int *)child_set_tid,
  307                     sizeof(p->p_pid));
  308 
  309         return;
  310 }
  311 
  312 int
  313 linux_set_tid_address(struct thread *td, struct linux_set_tid_address_args *args)
  314 {
  315         struct linux_emuldata *em;
  316 
  317 #ifdef DEBUG
  318         if (ldebug(set_tid_address))
  319                 printf(ARGS(set_tid_address, "%p"), args->tidptr);
  320 #endif
  321 
  322         /* find the emuldata */
  323         em = em_find(td->td_proc, EMUL_DOLOCK);
  324 
  325         KASSERT(em != NULL, ("set_tid_address: emuldata not found.\n"));
  326 
  327         em->child_clear_tid = args->tidptr;
  328         td->td_retval[0] = td->td_proc->p_pid;
  329 
  330         EMUL_UNLOCK(&emul_lock);
  331         return 0;
  332 }
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FreeBSD/Linux Kernel Cross Reference sys/compat/linux/linux_emul.c

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