sys/kern/kern_context.c

   1 /*-
   2  * Copyright (c) 2002 Daniel M. Eischen <deischen@freebsd.org>
   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  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  29
  30 #include <sys/param.h>
  31 #include <sys/kernel.h>
  32 #include <sys/lock.h>
  33 #include <sys/mutex.h>
  34 #include <sys/proc.h>
  35 #include <sys/sysent.h>
  36 #include <sys/systm.h>
  37 #include <sys/sysproto.h>
  38 #include <sys/signalvar.h>
  39 #include <sys/ucontext.h>
  40
  41 /*
  42  * The first two fields of a ucontext_t are the signal mask and the machine
  43  * context.  The next field is uc_link; we want to avoid destroying the link
  44  * when copying out contexts.
  45  */
  46 #define UC_COPY_SIZE    offsetof(ucontext_t, uc_link)
  47
  48 #ifndef _SYS_SYSPROTO_H_
  49 struct getcontext_args {
  50         struct __ucontext *ucp;
  51 }
  52 struct setcontext_args {
  53         const struct __ucontext_t *ucp;
  54 }
  55 struct swapcontext_args {
  56         struct __ucontext *oucp;
  57         const struct __ucontext_t *ucp;
  58 }
  59 #endif
  60
  61 int
  62 getcontext(struct thread *td, struct getcontext_args *uap)
  63 {
  64         ucontext_t uc;
  65         int ret;
  66
  67         if (uap->ucp == NULL)
  68                 ret = EINVAL;
  69         else {
  70                 get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
  71                 PROC_LOCK(td->td_proc);
  72                 uc.uc_sigmask = td->td_sigmask;
  73                 PROC_UNLOCK(td->td_proc);
  74                 ret = copyout(&uc, uap->ucp, UC_COPY_SIZE);
  75         }
  76         return (ret);
  77 }
  78
  79 int
  80 setcontext(struct thread *td, struct setcontext_args *uap)
  81 {
  82         ucontext_t uc;
  83         int ret;
  84
  85         if (uap->ucp == NULL)
  86                 ret = EINVAL;
  87         else {
  88                 ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
  89                 if (ret == 0) {
  90                         ret = set_mcontext(td, &uc.uc_mcontext);
  91                         if (ret == 0) {
  92                                 SIG_CANTMASK(uc.uc_sigmask);
  93                                 PROC_LOCK(td->td_proc);
  94                                 td->td_sigmask = uc.uc_sigmask;
  95                                 PROC_UNLOCK(td->td_proc);
  96                         }
  97                 }
  98         }
  99         return (ret == 0 ? EJUSTRETURN : ret);
 100 }
 101
 102 int
 103 swapcontext(struct thread *td, struct swapcontext_args *uap)
 104 {
 105         ucontext_t uc;
 106         int ret;
 107
 108         if (uap->oucp == NULL || uap->ucp == NULL)
 109                 ret = EINVAL;
 110         else {
 111                 get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
 112                 PROC_LOCK(td->td_proc);
 113                 uc.uc_sigmask = td->td_sigmask;
 114                 PROC_UNLOCK(td->td_proc);
 115                 ret = copyout(&uc, uap->oucp, UC_COPY_SIZE);
 116                 if (ret == 0) {
 117                         ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
 118                         if (ret == 0) {
 119                                 ret = set_mcontext(td, &uc.uc_mcontext);
 120                                 if (ret == 0) {
 121                                         SIG_CANTMASK(uc.uc_sigmask);
 122                                         PROC_LOCK(td->td_proc);
 123                                         td->td_sigmask = uc.uc_sigmask;
 124                                         PROC_UNLOCK(td->td_proc);
 125                                 }
 126                         }
 127                 }
 128         }
 129         return (ret == 0 ? EJUSTRETURN : ret);
 130 }