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1 jermar 1 
/*
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 * Copyright (c) 2005 Jakub Jermar
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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/** @addtogroup ia32
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 * @{
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 */
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/** @file
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 */
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#include <userspace.h>
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#include <arch/pm.h>
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#include <arch/types.h>
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#include <arch.h>
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#include <proc/uarg.h>
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#include <mm/as.h>
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/** Enter userspace
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 *
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 * Change CPU protection level to 3, enter userspace.
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 *
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 */
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void userspace(uspace_arg_t *kernel_uarg)
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{
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    ipl_t ipl = interrupts_disable();
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    asm volatile (
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        /*
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         * Clear nested task flag.
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         */
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        "pushfl\n"
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        "pop %%eax\n"
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        "and $0xffffbfff, %%eax\n"
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        "push %%eax\n"
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        "popfl\n"
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        /* Set up GS register (TLS) */
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        "movl %[tls_des], %%gs\n"
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        "pushl %[udata_des]\n"
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        "pushl %[stack_size]\n"
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        "pushl %[ipl]\n"
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        "pushl %[utext_des]\n"
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        "pushl %[entry]\n"
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        "movl %[uarg], %%eax\n"
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        /* %ebx is defined to hold pcb_ptr - set it to 0 */
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        "xorl %%ebx, %%ebx\n"
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        "iret\n"
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        :
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        : [udata_des] "i" (gdtselector(UDATA_DES) | PL_USER),
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          [stack_size] "r" ((uint8_t *) kernel_uarg->uspace_stack + THREAD_STACK_SIZE),
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          [ipl] "r" (ipl),
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          [utext_des] "i" (gdtselector(UTEXT_DES) | PL_USER),
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          [entry] "r" (kernel_uarg->uspace_entry),
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          [uarg] "r" (kernel_uarg->uspace_uarg),
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          [tls_des] "r" (gdtselector(TLS_DES))
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        : "eax");
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    /* Unreachable */
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    while (1);
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}
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/** @}
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 */