kernel/arch/ia32xen/src/userspace.c

   1 /*
   2  * Copyright (c) 2005 Jakub Jermar
   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  *
   9  * - Redistributions of source code must retain the above copyright
  10  *   notice, this list of conditions and the following disclaimer.
  11  * - 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  * - 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 /** @addtogroup ia32xen
  30  * @{
  31  */
  32 /** @file
  33  */
  34
  35 #include <userspace.h>
  36 #include <arch/pm.h>
  37 #include <arch/types.h>
  38 #include <arch.h>
  39 #include <proc/uarg.h>
  40 #include <mm/as.h>
  41
  42
  43 /** Enter userspace
  44  *
  45  * Change CPU protection level to 3, enter userspace.
  46  *
  47  */
  48 void userspace(uspace_arg_t *kernel_uarg)
  49 {
  50         uint32_t ipl = interrupts_disable();
  51
  52         asm volatile (
  53                 /*
  54                  * Clear nested task flag.
  55                  */
  56                 "pushfl\n"
  57                 "pop %%eax\n"
  58                 "and $0xffffbfff, %%eax\n"
  59                 "push %%eax\n"
  60                 "popfl\n"
  61
  62                 /* Set up GS register (TLS) */
  63                 "movl %6, %%gs\n"
  64
  65                 "pushl %0\n"
  66                 "pushl %1\n"
  67                 "pushl %2\n"
  68                 "pushl %3\n"
  69                 "pushl %4\n"
  70                 "movl %5, %%eax\n"
  71                 "iret\n"
  72                 :
  73                 : "i" (selector(UDATA_DES) | PL_USER),
  74                   "r" (kernel_uarg->uspace_stack + THREAD_STACK_SIZE),
  75                   "r" (ipl),
  76                   "i" (selector(UTEXT_DES) | PL_USER),
  77                   "r" (kernel_uarg->uspace_entry),
  78                   "r" (kernel_uarg->uspace_uarg),
  79                   "r" (selector(TLS_DES))
  80                 : "eax"
  81         );
  82
  83         /* Unreachable */
  84         for(;;)
  85                 ;
  86 }
  87
  88 /** @}
  89  */