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/**************************************************************************
* arch/x86/src/qemu/qemu_fullcontextrestore.S
*
* Copyright (C) 2011-2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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
* COPYRIGHT OWNER OR CONTRIBUTORS 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.
*
**************************************************************************/
/**************************************************************************
* Conditional Compilation Options
**************************************************************************/
/**************************************************************************
* Included Files
**************************************************************************/
#include <nuttx/config.h>
#include <arch/irq.h>
#include "up_internal.h"
.file "qemu_fullcontextrestore.S"
/**************************************************************************
* Pre-processor Definitions
**************************************************************************/
/**************************************************************************
* Global Variables
**************************************************************************/
/****************************************************************************
* Macros
****************************************************************************/
/* Trace macros, use like trace 'i' to print char to serial port. */
.macro chout, addr, ch
#ifdef CONFIG_DEBUG
mov $\addr, %dx
mov $\ch, %al
out %al, %dx
#endif
.endm
.macro trace, ch
#ifdef CONFIG_DEBUG
push %eax
push %edx
chout 0x3f8, \ch
pop %edx
pop %eax
#endif
.endm
/**************************************************************************
* Public Functions
**************************************************************************/
.text
/**************************************************************************
* Name: up_fullcontextrestore
*
* Full C prototype:
* void up_fullcontextrestore(uint32_t *regs) noreturn_function;
*
**************************************************************************/
.globl up_fullcontextrestore
.type up_fullcontextrestore, @function
up_fullcontextrestore:
/* Fetch the pointer to the register save array in EAX. */
movl 4(%esp), %eax
/* Disable interrupts now (the correct EFLAGS will be restored before we
* return
*/
cli
/* Get the value of the stack pointer as it was when the pusha was
* executed the interrupt handler.
*/
movl (4*REG_SP)(%eax), %esp
/* Create an interrupt stack frame for the final iret.
*
*
* IRET STACK
* PRIO CHANGE No PRIO CHANGE
* --------------- -----------------
* SP Before ->
* SS EFLAGS
* ESP CS
* EFLAGS -> EIP
* CS ...
* SP After -> EIP
*
* So, first check for a priority change.
*/
movl (4*REG_CS)(%eax), %edx
andl $3, %edx
mov %cs, %ebx
andl $3, %ebx
cmpb %bl, %dl
je .Lnopriochange
/* The priority will change... put SS and ESP on the stack */
mov (4*REG_SS)(%eax), %ebx
push %ebx
movl (4*REG_SP)(%eax), %ebx
push %ebx
.Lnopriochange:
movl (4*REG_EFLAGS)(%eax), %ebx
push %ebx
mov (4*REG_CS)(%eax), %ebx
push %ebx
movl (4*REG_EIP)(%eax), %ebx
push %ebx
/* Save the value of EAX on the stack too */
movl (4*REG_EAX)(%eax), %ebx
push %ebx
/* Now restore the remaining registers */
movl (4*REG_ESI)(%eax), %esi
movl (4*REG_EDI)(%eax), %edi
movl (4*REG_EBP)(%eax), %ebp
movl (4*REG_EBX)(%eax), %ebx
movl (4*REG_EDX)(%eax), %edx
movl (4*REG_ECX)(%eax), %ecx
/* Restore the data segment register. I think there is an issue that will
* need to be address here at some time: If the register save area is in
* one data segment and the stack is in another, then the above would not
* work (and, conversely, if they are in the same data segment, the
* following is unnecessary and redundant).
*/
mov (4*REG_DS)(%eax), %ds
/* Restore the correct value of EAX and then return */
popl %eax
iret
.size up_fullcontextrestore, . - up_fullcontextrestore
.end
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