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/****************************************************************************
* arch/x86/src/i486/up_savestate.c
*
* Copyright (C) 2011 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <debug.h>
#include <arch/arch.h>
#include <arch/irq.h>
#include "up_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_savestate
*
* Description:
* This function saves the interrupt level context information in the
* TCB. This would just be a up_copystate but we have to handle one
* special case. In the case where the privilige level changes, the
* value of sp and ss will not be saved on stack by the interrupt handler.
* So, in that case, we will have to fudge those values here.
*
****************************************************************************/
void up_savestate(uint32_t *regs)
{
uint8_t cpl;
uint8_t rpl;
/* First, just copy all of the registers */
up_copystate(regs, (uint32_t*)current_regs);
/* The RES_SP and REG_SS values will not be saved by the interrupt handling
* logic if there is no change in privilege level. In that case, we will
* have to "fudge" those values here. For now, just overwrite the REG_SP
* and REG_SS values with what we believe to be correct. Obviously, this
* will have to change in the future to support multi-segment operation.
*
* Check for a change in privilege level.
*/
rpl = regs[REG_CS] & 3;
cpl = up_getcs() & 3;
DEBUGASSERT(rpl >= cpl);
if (rpl == cpl)
{
/* No priority change, SP and SS are not present in the stack frame.
*
* The value saved in the REG_ESP will be the stackpointer value prior to
* the execution of the PUSHA. It will point at REG_IRQNO.
*/
regs[REG_SP] = current_regs[REG_ESP] + 4*BOTTOM_NOPRIO;
regs[REG_SS] = up_getss();
}
else
{
DEBUGASSERT(regs[REG_SP] == current_regs[REG_ESP] + 4*BOTTOM_PRIO);
}
}
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