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/*
 * Copyright (c) 2005 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup ia32
 * @{
 */
/** @file
 */

#include <userspace.h>
#include <arch/pm.h>
#include <arch/types.h>
#include <arch.h>
#include <proc/uarg.h>
#include <mm/as.h>


/** Enter userspace
 *
 * Change CPU protection level to 3, enter userspace.
 *
 */
void userspace(uspace_arg_t *kernel_uarg)
{
    ipl_t ipl = interrupts_disable();
    
    asm volatile (
        /*
         * Clear nested task flag.
         */
        "pushfl\n"
        "pop %%eax\n"
        "and $0xffffbfff, %%eax\n"
        "push %%eax\n"
        "popfl\n"
        
        /* Set up GS register (TLS) */
        "movl %[tls_des], %%gs\n"
        
        "pushl %[udata_des]\n"
        "pushl %[stack_size]\n"
        "pushl %[ipl]\n"
        "pushl %[utext_des]\n"
        "pushl %[entry]\n"
        "movl %[uarg], %%eax\n"
        
        /* %ebx is defined to hold pcb_ptr - set it to 0 */
        "xorl %%ebx, %%ebx\n"
        
        "iret\n"
        :
        : [udata_des] "i" (selector(UDATA_DES) | PL_USER),
          [stack_size] "r" ((uint8_t *) kernel_uarg->uspace_stack + THREAD_STACK_SIZE),
          [ipl] "r" (ipl),
          [utext_des] "i" (selector(UTEXT_DES) | PL_USER),
          [entry] "r" (kernel_uarg->uspace_entry),
          [uarg] "r" (kernel_uarg->uspace_uarg),
          [tls_des] "r" (selector(TLS_DES))
        : "eax");
    
    /* Unreachable */
    while (1);
}

/** @}
 */