/****************************************************************************
* arch/arm/src/cortexm3/up_svcall.c
*
* Copyright (C) 2009 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 <stdint.h>
#include <string.h>
#include <assert.h>
#include <debug.h>
#include <arch/irq.h>
#include "os_internal.h"
#include "up_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Debug output from this file may interfere with context switching! */
#undef DEBUG_SVCALL /* Define to debug SVCall */
#ifdef DEBUG_HARDFAULTS
# define svcdbg(format, arg...) lldbg(format, ##arg)
#else
# define svcdbg(x...)
#endif
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Public Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_svcall
*
* Description:
* This is SVCall exception handler that performs context switching
*
****************************************************************************/
int up_svcall(int irq, FAR void *context)
{
uint32_t *regs = (uint32_t*)context;
DEBUGASSERT(regs && regs == current_regs);
DEBUGASSERT(regs[REG_R1] != 0);
/* The SVCall software interrupt is called with R0 = SVC command and R1 =
* the TCB register save area.
*/
svcdbg("Command: %d regs: %p R1: %08x R2: %08x\n",
regs[REG_R0], regs, regs[REG_R1], regs[REG_R2]);
svcdbg("SVCall Entry:\n");
svcdbg(" R0: %08x %08x %08x %08x %08x %08x %08x %08x\n",
regs[REG_R0], regs[REG_R1], regs[REG_R2], regs[REG_R3],
regs[REG_R4], regs[REG_R5], regs[REG_R6], regs[REG_R7]);
svcdbg(" R8: %08x %08x %08x %08x %08x %08x %08x %08x\n",
regs[REG_R8], regs[REG_R9], regs[REG_R10], regs[REG_R11],
regs[REG_R12], regs[REG_R13], regs[REG_R14], regs[REG_R15]);
svcdbg(" PSR=%08x\n", regs[REG_XPSR]);
/* Handle the SVCall according to the command in R0 */
switch (regs[REG_R0])
{
/* R0=0: This is a save context command:
*
* int up_saveusercontext(uint32_t *saveregs);
*
* At this point, the following values are saved in context:
*
* R0 = 0
* R1 = saveregs
*
* In this case, we simply need to copy the current regsters to the
* save regiser space references in the saved R1 and return.
*/
case 0:
{
memcpy((uint32_t*)regs[REG_R1], regs, XCPTCONTEXT_SIZE);
}
break;
/* R0=1: This a restore context command:
*
* void up_fullcontextrestore(uint32_t *restoreregs) __attribute__ ((noreturn));
*
* At this point, the following values are saved in context:
*
* R0 = 1
* R1 = restoreregs
*
* In this case, we simply need to set current_regs to restore register
* area referenced in the saved R1. context == current_regs is the normal
* exception return. By setting current_regs = context[R1], we force
* the return to the saved context referenced in R1.
*/
case 1:
{
current_regs = (uint32_t*)regs[REG_R1];
}
break;
/* R0=2: This a switch context command:
*
* void up_switchcontext(uint32_t *saveregs, uint32_t *restoreregs);
*
* At this point, the following values are saved in context:
*
* R0 = 1
* R1 = saveregs
* R2 = restoreregs
*
* In this case, we do both: We save the context registers to the save
* register area reference by the saved contents of R1 nad then set
* current_regs to to the save register area referenced by the saved
* contents of R2.
*/
case 2:
{
DEBUGASSERT(regs[REG_R2] != 0);
memcpy((uint32_t*)regs[REG_R1], regs, XCPTCONTEXT_SIZE);
current_regs = (uint32_t*)regs[REG_R2];
}
break;
default:
PANIC(OSERR_INTERNAL);
break;
}
svcdbg("SVCall Return:\n");
svcdbg(" R0: %08x %08x %08x %08x %08x %08x %08x %08x\n",
current_regs[REG_R0], current_regs[REG_R1], current_regs[REG_R2], current_regs[REG_R3],
current_regs[REG_R4], current_regs[REG_R5], current_regs[REG_R6], current_regs[REG_R7]);
svcdbg(" R8: %08x %08x %08x %08x %08x %08x %08x %08x\n",
current_regs[REG_R8], current_regs[REG_R9], current_regs[REG_R10], current_regs[REG_R11],
current_regs[REG_R12], current_regs[REG_R13], current_regs[REG_R14], current_regs[REG_R15]);
svcdbg(" PSR=%08x\n", current_regs[REG_XPSR]);
return OK;
}
