The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*-
    2  * Copyright (c) 2006 Roman Divacky
    3  * Copyright (c) 2013 Dmitry Chagin
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer
   11  *    in this position and unchanged.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  * 3. The name of the author may not be used to endorse or promote products
   16  *    derived from this software without specific prior written permission
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   28  */
   29 
   30 #include <sys/cdefs.h>
   31 __FBSDID("$FreeBSD: releng/11.1/sys/compat/linux/linux_emul.c 303005 2016-07-18 16:34:11Z dchagin $");
   32 
   33 #include <sys/param.h>
   34 #include <sys/systm.h>
   35 #include <sys/imgact.h>
   36 #include <sys/kernel.h>
   37 #include <sys/ktr.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 
   46 #include <compat/linux/linux_emul.h>
   47 #include <compat/linux/linux_misc.h>
   48 #include <compat/linux/linux_persona.h>
   49 #include <compat/linux/linux_util.h>
   50 
   51 
   52 /*
   53  * This returns reference to the thread emuldata entry (if found)
   54  *
   55  * Hold PROC_LOCK when referencing emuldata from other threads.
   56  */
   57 struct linux_emuldata *
   58 em_find(struct thread *td)
   59 {
   60         struct linux_emuldata *em;
   61 
   62         em = td->td_emuldata;
   63 
   64         return (em);
   65 }
   66 
   67 /*
   68  * This returns reference to the proc pemuldata entry (if found)
   69  *
   70  * Hold PROC_LOCK when referencing proc pemuldata from other threads.
   71  * Hold LINUX_PEM_LOCK wher referencing pemuldata members.
   72  */
   73 struct linux_pemuldata *
   74 pem_find(struct proc *p)
   75 {
   76         struct linux_pemuldata *pem;
   77 
   78         pem = p->p_emuldata;
   79 
   80         return (pem);
   81 }
   82 
   83 void
   84 linux_proc_init(struct thread *td, struct thread *newtd, int flags)
   85 {
   86         struct linux_emuldata *em;
   87         struct linux_pemuldata *pem;
   88         struct epoll_emuldata *emd;
   89         struct proc *p;
   90 
   91         if (newtd != NULL) {
   92                 p = newtd->td_proc;
   93 
   94                 /* non-exec call */
   95                 em = malloc(sizeof(*em), M_TEMP, M_WAITOK | M_ZERO);
   96                 if (flags & LINUX_CLONE_THREAD) {
   97                         LINUX_CTR1(proc_init, "thread newtd(%d)",
   98                             newtd->td_tid);
   99 
  100                         em->em_tid = newtd->td_tid;
  101                 } else {
  102                         LINUX_CTR1(proc_init, "fork newtd(%d)", p->p_pid);
  103 
  104                         em->em_tid = p->p_pid;
  105 
  106                         pem = malloc(sizeof(*pem), M_LINUX, M_WAITOK | M_ZERO);
  107                         sx_init(&pem->pem_sx, "lpemlk");
  108                         p->p_emuldata = pem;
  109                 }
  110                 newtd->td_emuldata = em;
  111         } else {
  112                 p = td->td_proc;
  113 
  114                 /* exec */
  115                 LINUX_CTR1(proc_init, "exec newtd(%d)", p->p_pid);
  116 
  117                 /* lookup the old one */
  118                 em = em_find(td);
  119                 KASSERT(em != NULL, ("proc_init: emuldata not found in exec case.\n"));
  120 
  121                 em->em_tid = p->p_pid;
  122                 em->flags = 0;
  123                 em->pdeath_signal = 0;
  124                 em->robust_futexes = NULL;
  125                 em->child_clear_tid = NULL;
  126                 em->child_set_tid = NULL;
  127 
  128                  /* epoll should be destroyed in a case of exec. */
  129                 pem = pem_find(p);
  130                 KASSERT(pem != NULL, ("proc_exit: proc emuldata not found.\n"));
  131                 pem->persona = 0;
  132                 if (pem->epoll != NULL) {
  133                         emd = pem->epoll;
  134                         pem->epoll = NULL;
  135                         free(emd, M_EPOLL);
  136                 }
  137         }
  138 
  139 }
  140 
  141 void 
  142 linux_proc_exit(void *arg __unused, struct proc *p)
  143 {
  144         struct linux_pemuldata *pem;
  145         struct epoll_emuldata *emd;
  146         struct thread *td = curthread;
  147 
  148         if (__predict_false(SV_CURPROC_ABI() != SV_ABI_LINUX))
  149                 return;
  150 
  151         LINUX_CTR3(proc_exit, "thread(%d) proc(%d) p %p",
  152             td->td_tid, p->p_pid, p);
  153 
  154         pem = pem_find(p);
  155         if (pem == NULL)
  156                 return; 
  157         (p->p_sysent->sv_thread_detach)(td);
  158 
  159         p->p_emuldata = NULL;
  160 
  161         if (pem->epoll != NULL) {
  162                 emd = pem->epoll;
  163                 pem->epoll = NULL;
  164                 free(emd, M_EPOLL);
  165         }
  166 
  167         sx_destroy(&pem->pem_sx);
  168         free(pem, M_LINUX);
  169 }
  170 
  171 int 
  172 linux_common_execve(struct thread *td, struct image_args *eargs)
  173 {
  174         struct linux_pemuldata *pem;
  175         struct epoll_emuldata *emd;
  176         struct vmspace *oldvmspace;
  177         struct linux_emuldata *em;
  178         struct proc *p;
  179         int error;
  180 
  181         p = td->td_proc;
  182 
  183         error = pre_execve(td, &oldvmspace);
  184         if (error != 0)
  185                 return (error);
  186 
  187         error = kern_execve(td, eargs, NULL);
  188         post_execve(td, error, oldvmspace);
  189         if (error != 0)
  190                 return (error);
  191 
  192         /*
  193          * In a case of transition from Linux binary execing to
  194          * FreeBSD binary we destroy linux emuldata thread & proc entries.
  195          */
  196         if (SV_CURPROC_ABI() != SV_ABI_LINUX) {
  197                 PROC_LOCK(p);
  198                 em = em_find(td);
  199                 KASSERT(em != NULL, ("proc_exec: thread emuldata not found.\n"));
  200                 td->td_emuldata = NULL;
  201 
  202                 pem = pem_find(p);
  203                 KASSERT(pem != NULL, ("proc_exec: proc pemuldata not found.\n"));
  204                 p->p_emuldata = NULL;
  205                 PROC_UNLOCK(p);
  206 
  207                 if (pem->epoll != NULL) {
  208                         emd = pem->epoll;
  209                         pem->epoll = NULL;
  210                         free(emd, M_EPOLL);
  211                 }
  212 
  213                 free(em, M_TEMP);
  214                 free(pem, M_LINUX);
  215         }
  216         return (0);
  217 }
  218 
  219 void 
  220 linux_proc_exec(void *arg __unused, struct proc *p, struct image_params *imgp)
  221 {
  222         struct thread *td = curthread;
  223         struct thread *othertd;
  224 #if defined(__amd64__)
  225         struct linux_pemuldata *pem;
  226 #endif
  227 
  228         /*
  229          * In a case of execing from linux binary properly detach
  230          * other threads from the user space.
  231          */
  232         if (__predict_false(SV_PROC_ABI(p) == SV_ABI_LINUX)) {
  233                 FOREACH_THREAD_IN_PROC(p, othertd) {
  234                         if (td != othertd)
  235                                 (p->p_sysent->sv_thread_detach)(othertd);
  236                 }
  237         }
  238 
  239         /*
  240          * In a case of execing to linux binary we create linux
  241          * emuldata thread entry.
  242          */
  243         if (__predict_false((imgp->sysent->sv_flags & SV_ABI_MASK) ==
  244             SV_ABI_LINUX)) {
  245 
  246                 if (SV_PROC_ABI(p) == SV_ABI_LINUX)
  247                         linux_proc_init(td, NULL, 0);
  248                 else
  249                         linux_proc_init(td, td, 0);
  250 #if defined(__amd64__)
  251                 /*
  252                  * An IA32 executable which has executable stack will have the
  253                  * READ_IMPLIES_EXEC personality flag set automatically.
  254                  */
  255                 if (SV_PROC_FLAG(td->td_proc, SV_ILP32) &&
  256                     imgp->stack_prot & VM_PROT_EXECUTE) {
  257                         pem = pem_find(p);
  258                         pem->persona |= LINUX_READ_IMPLIES_EXEC;
  259                 }
  260 #endif
  261         }
  262 }
  263 
  264 void
  265 linux_thread_dtor(void *arg __unused, struct thread *td)
  266 {
  267         struct linux_emuldata *em;
  268 
  269         em = em_find(td);
  270         if (em == NULL)
  271                 return;
  272         td->td_emuldata = NULL;
  273 
  274         LINUX_CTR1(thread_dtor, "thread(%d)", em->em_tid);
  275 
  276         free(em, M_TEMP);
  277 }
  278 
  279 void
  280 linux_schedtail(struct thread *td)
  281 {
  282         struct linux_emuldata *em;
  283         struct proc *p;
  284         int error = 0;
  285         int *child_set_tid;
  286 
  287         p = td->td_proc;
  288 
  289         em = em_find(td);
  290         KASSERT(em != NULL, ("linux_schedtail: thread emuldata not found.\n"));
  291         child_set_tid = em->child_set_tid;
  292 
  293         if (child_set_tid != NULL) {
  294                 error = copyout(&em->em_tid, child_set_tid,
  295                     sizeof(em->em_tid));
  296                 LINUX_CTR4(schedtail, "thread(%d) %p stored %d error %d",
  297                     td->td_tid, child_set_tid, em->em_tid, error);
  298         } else
  299                 LINUX_CTR1(schedtail, "thread(%d)", em->em_tid);
  300 }

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