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: releng/8.4/sys/compat/linux/linux_emul.c 222846 2011-06-08 03:45:40Z dchagin $");
   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/sysent.h>
   45 #include <sys/sysproto.h>
   46 #include <sys/unistd.h>
   47 
   48 #ifdef COMPAT_LINUX32
   49 #include <machine/../linux32/linux.h>
   50 #include <machine/../linux32/linux32_proto.h>
   51 #else
   52 #include <machine/../linux/linux.h>
   53 #include <machine/../linux/linux_proto.h>
   54 #endif
   55 
   56 #include <compat/linux/linux_emul.h>
   57 #include <compat/linux/linux_futex.h>
   58 
   59 struct sx       emul_shared_lock;
   60 struct mtx      emul_lock;
   61 
   62 /* this returns locked reference to the emuldata entry (if found) */
   63 struct linux_emuldata *
   64 em_find(struct proc *p, int locked)
   65 {
   66         struct linux_emuldata *em;
   67 
   68         if (locked == EMUL_DOLOCK)
   69                 EMUL_LOCK(&emul_lock);
   70 
   71         em = p->p_emuldata;
   72 
   73         if (em == NULL && locked == EMUL_DOLOCK)
   74                 EMUL_UNLOCK(&emul_lock);
   75 
   76         return (em);
   77 }
   78 
   79 int
   80 linux_proc_init(struct thread *td, pid_t child, int flags)
   81 {
   82         struct linux_emuldata *em, *p_em;
   83         struct proc *p;
   84 
   85         if (child != 0) {
   86                 /* non-exec call */
   87                 em = malloc(sizeof *em, M_LINUX, M_WAITOK | M_ZERO);
   88                 em->pid = child;
   89                 em->pdeath_signal = 0;
   90                 em->flags = 0;
   91                 em->robust_futexes = NULL;
   92                 if (flags & LINUX_CLONE_THREAD) {
   93                         /* handled later in the code */
   94                 } else {
   95                         struct linux_emuldata_shared *s;
   96 
   97                         s = malloc(sizeof *s, M_LINUX, M_WAITOK | M_ZERO);
   98                         s->refs = 1;
   99                         s->group_pid = child;
  100 
  101                         LIST_INIT(&s->threads);
  102                         em->shared = s;
  103                 }
  104         } else {
  105                 /* lookup the old one */
  106                 em = em_find(td->td_proc, EMUL_DOLOCK);
  107                 KASSERT(em != NULL, ("proc_init: emuldata not found in exec case.\n"));
  108         }
  109 
  110         em->child_clear_tid = NULL;
  111         em->child_set_tid = NULL;
  112 
  113         /*
  114          * allocate the shared struct only in clone()/fork cases in the case
  115          * of clone() td = calling proc and child = pid of the newly created
  116          * proc
  117          */
  118         if (child != 0) {
  119                 if (flags & LINUX_CLONE_THREAD) {
  120                         /* lookup the parent */
  121                         /* 
  122                          * we dont have to lock the p_em because
  123                          * its waiting for us in linux_clone so
  124                          * there is no chance of it changing the
  125                          * p_em->shared address
  126                          */
  127                         p_em = em_find(td->td_proc, EMUL_DONTLOCK);
  128                         KASSERT(p_em != NULL, ("proc_init: parent emuldata not found for CLONE_THREAD\n"));
  129                         em->shared = p_em->shared;
  130                         EMUL_SHARED_WLOCK(&emul_shared_lock);
  131                         em->shared->refs++;
  132                         EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  133                 } else {
  134                         /*
  135                          * handled earlier to avoid malloc(M_WAITOK) with
  136                          * rwlock held
  137                          */
  138                 }
  139         }
  140         if (child != 0) {
  141                 EMUL_SHARED_WLOCK(&emul_shared_lock);
  142                 LIST_INSERT_HEAD(&em->shared->threads, em, threads);
  143                 EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  144 
  145                 p = pfind(child);
  146                 KASSERT(p != NULL, ("process not found in proc_init\n"));
  147                 p->p_emuldata = em;
  148                 PROC_UNLOCK(p);
  149         } else
  150                 EMUL_UNLOCK(&emul_lock);
  151 
  152         return (0);
  153 }
  154 
  155 void
  156 linux_proc_exit(void *arg __unused, struct proc *p)
  157 {
  158         struct linux_emuldata *em;
  159         int error, shared_flags, shared_xstat;
  160         struct thread *td = FIRST_THREAD_IN_PROC(p);
  161         int *child_clear_tid;
  162         struct proc *q, *nq;
  163 
  164         if (__predict_true(p->p_sysent != &elf_linux_sysvec))
  165                 return;
  166 
  167         release_futexes(p);
  168 
  169         /* find the emuldata */
  170         em = em_find(p, EMUL_DOLOCK);
  171 
  172         KASSERT(em != NULL, ("proc_exit: emuldata not found.\n"));
  173 
  174         /* reparent all procs that are not a thread leader to initproc */
  175         if (em->shared->group_pid != p->p_pid) {
  176                 child_clear_tid = em->child_clear_tid;
  177                 EMUL_UNLOCK(&emul_lock);
  178                 sx_xlock(&proctree_lock);
  179                 wakeup(initproc);
  180                 PROC_LOCK(p);
  181                 proc_reparent(p, initproc);
  182                 p->p_sigparent = SIGCHLD;
  183                 PROC_UNLOCK(p);
  184                 sx_xunlock(&proctree_lock);
  185         } else {
  186                 child_clear_tid = em->child_clear_tid;
  187                 EMUL_UNLOCK(&emul_lock);        
  188         }
  189 
  190         EMUL_SHARED_WLOCK(&emul_shared_lock);
  191         shared_flags = em->shared->flags;
  192         shared_xstat = em->shared->xstat;
  193         LIST_REMOVE(em, threads);
  194 
  195         em->shared->refs--;
  196         if (em->shared->refs == 0) {
  197                 EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  198                 free(em->shared, M_LINUX);
  199         } else  
  200                 EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  201 
  202         if ((shared_flags & EMUL_SHARED_HASXSTAT) != 0)
  203                 p->p_xstat = shared_xstat;
  204 
  205         if (child_clear_tid != NULL) {
  206                 struct linux_sys_futex_args cup;
  207                 int null = 0;
  208 
  209                 error = copyout(&null, child_clear_tid, sizeof(null));
  210                 if (error) {
  211                         free(em, M_LINUX);
  212                         return;
  213                 }
  214 
  215                 /* futexes stuff */
  216                 cup.uaddr = child_clear_tid;
  217                 cup.op = LINUX_FUTEX_WAKE;
  218                 cup.val = 0x7fffffff;   /* Awake everyone */
  219                 cup.timeout = NULL;
  220                 cup.uaddr2 = NULL;
  221                 cup.val3 = 0;
  222                 error = linux_sys_futex(FIRST_THREAD_IN_PROC(p), &cup);
  223                 /*
  224                  * this cannot happen at the moment and if this happens it
  225                  * probably means there is a user space bug
  226                  */
  227                 if (error)
  228                         printf(LMSG("futex stuff in proc_exit failed.\n"));
  229         }
  230 
  231         /* clean the stuff up */
  232         free(em, M_LINUX);
  233 
  234         /* this is a little weird but rewritten from exit1() */
  235         sx_xlock(&proctree_lock);
  236         q = LIST_FIRST(&p->p_children);
  237         for (; q != NULL; q = nq) {
  238                 nq = LIST_NEXT(q, p_sibling);
  239                 if (q->p_flag & P_WEXIT)
  240                         continue;
  241                 if (__predict_false(q->p_sysent != &elf_linux_sysvec))
  242                         continue;
  243                 em = em_find(q, EMUL_DOLOCK);
  244                 KASSERT(em != NULL, ("linux_reparent: emuldata not found: %i\n", q->p_pid));
  245                 PROC_LOCK(q);
  246                 if ((q->p_flag & P_WEXIT) == 0 && em->pdeath_signal != 0) {
  247                         psignal(q, em->pdeath_signal);
  248                 }
  249                 PROC_UNLOCK(q);
  250                 EMUL_UNLOCK(&emul_lock);
  251         }
  252         sx_xunlock(&proctree_lock);
  253 }
  254 
  255 /*
  256  * This is used in a case of transition from FreeBSD binary execing to linux binary
  257  * in this case we create linux emuldata proc entry with the pid of the currently running
  258  * process.
  259  */
  260 void 
  261 linux_proc_exec(void *arg __unused, struct proc *p, struct image_params *imgp)
  262 {
  263         if (__predict_false(imgp->sysent == &elf_linux_sysvec
  264             && p->p_sysent != &elf_linux_sysvec))
  265                 linux_proc_init(FIRST_THREAD_IN_PROC(p), p->p_pid, 0);
  266         if (__predict_false((p->p_sysent->sv_flags & SV_ABI_MASK) ==
  267             SV_ABI_LINUX))
  268                 /* Kill threads regardless of imgp->sysent value */
  269                 linux_kill_threads(FIRST_THREAD_IN_PROC(p), SIGKILL);
  270         if (__predict_false(imgp->sysent != &elf_linux_sysvec
  271             && p->p_sysent == &elf_linux_sysvec)) {
  272                 struct linux_emuldata *em;
  273 
  274                 /* 
  275                  * XXX:There's a race because here we assign p->p_emuldata NULL
  276                  * but the process is still counted as linux one for a short
  277                  * time so some other process might reference it and try to
  278                  * access its p->p_emuldata and panicing on a NULL reference.
  279                  */
  280                 em = em_find(p, EMUL_DONTLOCK);
  281 
  282                 KASSERT(em != NULL, ("proc_exec: emuldata not found.\n"));
  283 
  284                 EMUL_SHARED_WLOCK(&emul_shared_lock);
  285                 LIST_REMOVE(em, threads);
  286 
  287                 PROC_LOCK(p);
  288                 p->p_emuldata = NULL;
  289                 PROC_UNLOCK(p);
  290 
  291                 em->shared->refs--;
  292                 if (em->shared->refs == 0) {
  293                         EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  294                         free(em->shared, M_LINUX);
  295                 } else
  296                         EMUL_SHARED_WUNLOCK(&emul_shared_lock);
  297 
  298                 free(em, M_LINUX);
  299         }
  300 }
  301 
  302 void
  303 linux_schedtail(struct thread *td)
  304 {
  305         struct linux_emuldata *em;
  306         struct proc *p;
  307         int error = 0;
  308         int *child_set_tid;
  309 
  310         p = td->td_proc;
  311 
  312         /* find the emuldata */
  313         em = em_find(p, EMUL_DOLOCK);
  314 
  315         KASSERT(em != NULL, ("linux_schedtail: emuldata not found.\n"));
  316         child_set_tid = em->child_set_tid;
  317         EMUL_UNLOCK(&emul_lock);
  318 
  319         if (child_set_tid != NULL)
  320                 error = copyout(&p->p_pid, (int *)child_set_tid,
  321                     sizeof(p->p_pid));
  322 
  323         return;
  324 }
  325 
  326 int
  327 linux_set_tid_address(struct thread *td, struct linux_set_tid_address_args *args)
  328 {
  329         struct linux_emuldata *em;
  330 
  331 #ifdef DEBUG
  332         if (ldebug(set_tid_address))
  333                 printf(ARGS(set_tid_address, "%p"), args->tidptr);
  334 #endif
  335 
  336         /* find the emuldata */
  337         em = em_find(td->td_proc, EMUL_DOLOCK);
  338 
  339         KASSERT(em != NULL, ("set_tid_address: emuldata not found.\n"));
  340 
  341         em->child_clear_tid = args->tidptr;
  342         td->td_retval[0] = td->td_proc->p_pid;
  343 
  344         EMUL_UNLOCK(&emul_lock);
  345         return 0;
  346 }
  347 
  348 void
  349 linux_kill_threads(struct thread *td, int sig)
  350 {
  351         struct linux_emuldata *em, *td_em, *tmp_em;
  352         struct proc *sp;
  353 
  354         td_em = em_find(td->td_proc, EMUL_DONTLOCK);
  355 
  356         KASSERT(td_em != NULL, ("linux_kill_threads: emuldata not found.\n"));
  357 
  358         EMUL_SHARED_RLOCK(&emul_shared_lock);
  359         LIST_FOREACH_SAFE(em, &td_em->shared->threads, threads, tmp_em) {
  360                 if (em->pid == td_em->pid)
  361                         continue;
  362 
  363                 sp = pfind(em->pid);
  364                 if ((sp->p_flag & P_WEXIT) == 0)
  365                         psignal(sp, sig);
  366                 PROC_UNLOCK(sp);
  367 #ifdef DEBUG
  368                 printf(LMSG("linux_kill_threads: kill PID %d\n"), em->pid);
  369 #endif
  370         }
  371         EMUL_SHARED_RUNLOCK(&emul_shared_lock);
  372 }
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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
