armulmem.c

/*
  This file is a compy of armvirt.c, which is part of the ARMulator distributed 
  e.g. with gdb and skyeye. In order to overwrite GetWord and PutWord, 
  we had to copy the whole file.
  ReLoadInstr is also changed, in order to implement execution 
  prevention despite instruction prefetching.
*/
#include "GdbARMPlugin.h"

/*  armvirt.c -- ARMulator virtual memory interace:  ARM6 Instruction Emulator.
    Copyright (C) 1994 Advanced RISC Machines Ltd.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */

/* This file contains a complete ARMulator memory model, modelling a
"virtual memory" system. A much simpler model can be found in armfast.c,
and that model goes faster too, but has a fixed amount of memory. This
model's memory has 64K pages, allocated on demand from a 64K entry page
table. The routines PutWord and GetWord implement this. Pages are never
freed as they might be needed again. A single area of memory may be
defined to generate aborts. */

#include "armopts.h"
#include "armos.h"
#include "armdefs.h"
#include "ansidecl.h"

#ifdef VALIDATE			/* for running the validate suite */
#define TUBE 48 * 1024 * 1024	/* write a char on the screen */
#define ABORTS 1
#endif

/* #define ABORTS */

#ifdef ABORTS			/* the memory system will abort */
/* For the old test suite Abort between 32 Kbytes and 32 Mbytes
   For the new test suite Abort between 8 Mbytes and 26 Mbytes */
/* #define LOWABORT 32 * 1024
#define HIGHABORT 32 * 1024 * 1024 */
#define LOWABORT 8 * 1024 * 1024
#define HIGHABORT 26 * 1024 * 1024

#endif

#define NUMPAGES 64 * 1024
#define PAGESIZE 64 * 1024
#define PAGEBITS 16
#define OFFSETBITS 0xffff

int SWI_vector_installed = FALSE;

#include <stdio.h>

/***************************************************************************\
*        Get a Word from Memory          *
\***************************************************************************/

static ARMword
GetWord (ARMul_State * state, ARMword address, int check)
{
  if(address < minReadAddress || address + 4 > (state->MemSize))
  {
    //raise memory access error
    state->Emulate = FALSE;
    state->EndCondition = MemoryBoundsError;
    gdb_log_printf(NULL, "Illegal memory read at %#p. ", address);
    return 0;
  }
  else
  {
    return *((ARMword*) (state->MemDataPtr + address));
  }
}

/***************************************************************************\
*        Put a Word into Memory          *
\***************************************************************************/

static void
PutWord (ARMul_State * state, ARMword address, ARMword data, int check)
{
  if(address < minWriteAddress || address + 4 > (state->MemSize))
  {
    //raise memory access error
    state->Emulate = FALSE;
    state->EndCondition = MemoryBoundsError;
    gdb_log_printf(NULL, "Illegal memory write at %#p. ", address);
  } 
  else
  {
    *((ARMword*) (state->MemDataPtr + address)) = data;
  }
}

/***************************************************************************\
*                   ReLoad Instruction                                     *
\***************************************************************************/

ARMword
ARMul_ReLoadInstr (ARMul_State * state, ARMword address, ARMword isize)
{
#ifdef ABORTS
  if (address >= LOWABORT && address < HIGHABORT)
    {
      ARMul_PREFETCHABORT (address);
      return ARMul_ABORTWORD;
    }
  else
    {
      ARMul_CLEARABORT;
    }
#endif

  if (address < minReadAddress 
  	  || address >= (state->MemSize) 
  	  || (address >= minWriteAddress && minWriteAddress != 0))
  {
  	  // Custom SWI, defined in the wrapper of ARMul_OSHandleSWI
  	  return 0xEF000000 | 0x200000;
  	  //      ^ SWI         ^ SWI number
  }
  
  if ((isize == 2) && (address & 0x2))
    {
      /* We return the next two halfwords: */
      ARMword lo = GetWord (state, address, FALSE);
      ARMword hi = GetWord (state, address + 4, FALSE);

      if (state->bigendSig == HIGH)
	return (lo << 16) | (hi >> 16);
      else
	return ((hi & 0xFFFF) << 16) | (lo >> 16);
    }

  return GetWord (state, address, TRUE);
}

/***************************************************************************\
*                      Initialise the memory interface                      *
\***************************************************************************/

unsigned
ARMul_MemoryInit (ARMul_State * state, unsigned long initmemsize)
{
  ARMword **pagetable;
  unsigned page;

  if (initmemsize)
    state->MemSize = initmemsize;

  pagetable = (ARMword **) malloc (sizeof (ARMword *) * NUMPAGES);

  if (pagetable == NULL)
    return FALSE;

  for (page = 0; page < NUMPAGES; page++)
    *(pagetable + page) = NULL;

  state->MemDataPtr = (unsigned char *) pagetable;

  ARMul_ConsolePrint (state, ", 4 Gb memory");

  return TRUE;
}

/***************************************************************************\
*                         Remove the memory interface                       *
\***************************************************************************/

void
ARMul_MemoryExit (ARMul_State * state)
{
  ARMword page;
  ARMword **pagetable;
  ARMword *pageptr;

  pagetable = (ARMword **) state->MemDataPtr;
  for (page = 0; page < NUMPAGES; page++)
    {
      pageptr = *(pagetable + page);
      if (pageptr != NULL)
	free ((char *) pageptr);
    }
  free ((char *) pagetable);
  return;
}

/***************************************************************************\
*                   Load Instruction, Sequential Cycle                      *
\***************************************************************************/

ARMword ARMul_LoadInstrS (ARMul_State * state, ARMword address, ARMword isize)
{
  state->NumScycles++;

#ifdef HOURGLASS
  if ((state->NumScycles & HOURGLASS_RATE) == 0)
    {
      HOURGLASS;
    }
#endif

  return ARMul_ReLoadInstr (state, address, isize);
}

/***************************************************************************\
*                 Load Instruction, Non Sequential Cycle                    *
\***************************************************************************/

ARMword ARMul_LoadInstrN (ARMul_State * state, ARMword address, ARMword isize)
{
  state->NumNcycles++;

  return ARMul_ReLoadInstr (state, address, isize);
}

/***************************************************************************\
*                      Read Word (but don't tell anyone!)                   *
\***************************************************************************/

ARMword ARMul_ReadWord (ARMul_State * state, ARMword address)
{
#ifdef ABORTS
  if (address >= LOWABORT && address < HIGHABORT)
    {
      ARMul_DATAABORT (address);
      return ARMul_ABORTWORD;
    }
  else
    {
      ARMul_CLEARABORT;
    }
#endif

  return GetWord (state, address, TRUE);
}

/***************************************************************************\
*                        Load Word, Sequential Cycle                        *
\***************************************************************************/

ARMword ARMul_LoadWordS (ARMul_State * state, ARMword address)
{
  state->NumScycles++;

  return ARMul_ReadWord (state, address);
}

/***************************************************************************\
*                      Load Word, Non Sequential Cycle                      *
\***************************************************************************/

ARMword ARMul_LoadWordN (ARMul_State * state, ARMword address)
{
  state->NumNcycles++;

  return ARMul_ReadWord (state, address);
}

/***************************************************************************\
*                     Load Halfword, (Non Sequential Cycle)                 *
\***************************************************************************/

ARMword ARMul_LoadHalfWord (ARMul_State * state, ARMword address)
{
  ARMword temp, offset;

  state->NumNcycles++;

  temp = ARMul_ReadWord (state, address);
  offset = (((ARMword) state->bigendSig * 2) ^ (address & 2)) << 3;	/* bit offset into the word */

  return (temp >> offset) & 0xffff;
}

/***************************************************************************\
*                      Read Byte (but don't tell anyone!)                   *
\***************************************************************************/

ARMword ARMul_ReadByte (ARMul_State * state, ARMword address)
{
  ARMword temp, offset;

  temp = ARMul_ReadWord (state, address);
  offset = (((ARMword) state->bigendSig * 3) ^ (address & 3)) << 3;	/* bit offset into the word */

  return (temp >> offset & 0xffL);
}

/***************************************************************************\
*                     Load Byte, (Non Sequential Cycle)                     *
\***************************************************************************/

ARMword ARMul_LoadByte (ARMul_State * state, ARMword address)
{
  state->NumNcycles++;

  return ARMul_ReadByte (state, address);
}

/***************************************************************************\
*                     Write Word (but don't tell anyone!)                   *
\***************************************************************************/

void
ARMul_WriteWord (ARMul_State * state, ARMword address, ARMword data)
{
#ifdef ABORTS
  if (address >= LOWABORT && address < HIGHABORT)
    {
      ARMul_DATAABORT (address);
      return;
    }
  else
    {
      ARMul_CLEARABORT;
    }
#endif

  PutWord (state, address, data, TRUE);
}

/***************************************************************************\
*                       Store Word, Sequential Cycle                        *
\***************************************************************************/

void
ARMul_StoreWordS (ARMul_State * state, ARMword address, ARMword data)
{
  state->NumScycles++;

  ARMul_WriteWord (state, address, data);
}

/***************************************************************************\
*                       Store Word, Non Sequential Cycle                        *
\***************************************************************************/

void
ARMul_StoreWordN (ARMul_State * state, ARMword address, ARMword data)
{
  state->NumNcycles++;

  ARMul_WriteWord (state, address, data);
}

/***************************************************************************\
*                    Store HalfWord, (Non Sequential Cycle)                 *
\***************************************************************************/

void
ARMul_StoreHalfWord (ARMul_State * state, ARMword address, ARMword data)
{
  ARMword temp, offset;

  state->NumNcycles++;

#ifdef VALIDATE
  if (address == TUBE)
    {
      if (data == 4)
	state->Emulate = FALSE;
      else
	(void) putc ((char) data, stderr);	/* Write Char */
      return;
    }
#endif

  temp = ARMul_ReadWord (state, address);
  offset = (((ARMword) state->bigendSig * 2) ^ (address & 2)) << 3;	/* bit offset into the word */

  PutWord (state, address,
	   (temp & ~(0xffffL << offset)) | ((data & 0xffffL) << offset),
	   TRUE);
}

/***************************************************************************\
*                     Write Byte (but don't tell anyone!)                   *
\***************************************************************************/

void
ARMul_WriteByte (ARMul_State * state, ARMword address, ARMword data)
{
  ARMword temp, offset;

  temp = ARMul_ReadWord (state, address);
  offset = (((ARMword) state->bigendSig * 3) ^ (address & 3)) << 3;	/* bit offset into the word */

  PutWord (state, address,
	   (temp & ~(0xffL << offset)) | ((data & 0xffL) << offset),
	   TRUE);
}

/***************************************************************************\
*                    Store Byte, (Non Sequential Cycle)                     *
\***************************************************************************/

void
ARMul_StoreByte (ARMul_State * state, ARMword address, ARMword data)
{
  state->NumNcycles++;

#ifdef VALIDATE
  if (address == TUBE)
    {
      if (data == 4)
	state->Emulate = FALSE;
      else
	(void) putc ((char) data, stderr);	/* Write Char */
      return;
    }
#endif

  ARMul_WriteByte (state, address, data);
}

/***************************************************************************\
*                   Swap Word, (Two Non Sequential Cycles)                  *
\***************************************************************************/

ARMword ARMul_SwapWord (ARMul_State * state, ARMword address, ARMword data)
{
  ARMword temp;

  state->NumNcycles++;

  temp = ARMul_ReadWord (state, address);

  state->NumNcycles++;

  PutWord (state, address, data, TRUE);

  return temp;
}

/***************************************************************************\
*                   Swap Byte, (Two Non Sequential Cycles)                  *
\***************************************************************************/

ARMword ARMul_SwapByte (ARMul_State * state, ARMword address, ARMword data)
{
  ARMword temp;

  temp = ARMul_LoadByte (state, address);
  ARMul_StoreByte (state, address, data);

  return temp;
}

/***************************************************************************\
*                             Count I Cycles                                *
\***************************************************************************/

void
ARMul_Icycles (ARMul_State * state, unsigned number, ARMword address ATTRIBUTE_UNUSED)
{
  state->NumIcycles += number;
  ARMul_CLEARABORT;
}

/***************************************************************************\
*                             Count C Cycles                                *
\***************************************************************************/

void
ARMul_Ccycles (ARMul_State * state, unsigned number, ARMword address ATTRIBUTE_UNUSED)
{
  state->NumCcycles += number;
  ARMul_CLEARABORT;
}


/* Read a byte.  Do not check for alignment or access errors.  */

ARMword
ARMul_SafeReadByte (ARMul_State * state, ARMword address)
{
  ARMword temp, offset;

  temp = GetWord (state, address, FALSE);
  offset = (((ARMword) state->bigendSig * 3) ^ (address & 3)) << 3;

  return (temp >> offset & 0xffL);
}

void
ARMul_SafeWriteByte (ARMul_State * state, ARMword address, ARMword data)
{
  ARMword temp, offset;

  temp = GetWord (state, address, FALSE);
  offset = (((ARMword) state->bigendSig * 3) ^ (address & 3)) << 3;

  PutWord (state, address,
	   (temp & ~(0xffL << offset)) | ((data & 0xffL) << offset),
	   FALSE);
}