Subversion Repositories openrisc_2011-10-31

/*  This file is part of the program psim.

    Copyright (C) 1994-1996, Andrew Cagney <cagney@highland.com.au>

    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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

    */

#ifndef _HW_VM_C_

#define _HW_VM_C_

#include "device_table.h"

#include "cpu.h"

#include <signal.h>

/* DEVICE

   vm - virtual memory device for user simulation modes

   DESCRIPTION

   In user mode, mapped text, data and stack addresses are managed by

   the core.  Unmapped addresses are passed onto this device (because

   it establishes its self as the fallback device) for processing.

   During initialization, children of this device will request the

   mapping of the initial text and data segments.  Those requests are

   passed onto the core device so that that may establish the initial

   memory regions.

   Once the simulation has started (as noted above) any access to an

   unmapped address range will be passed down to this device as an IO

   access.  This device will then either attach additional memory to

   the core device or signal the access as being invalid.

   The IOCTL function is used to notify this device of any changes to

   the users `brk' point.

   PROPERTIES

   stack-base = <number>

   Specifies the lower address of the stack segment in the users

   virtual address space.  The initial stack page is defined by

   stack-base + nr-bytes.

   nr-bytes = <number>

   Specifies the maximum size of the stack segment in the users

   address space.

   */

typedef struct _hw_vm_device {

  /* area of memory valid for stack addresses */

  unsigned_word stack_base; /* min possible stack value */

  unsigned_word stack_bound;

  unsigned_word stack_lower_limit;

  /* area of memory valid for heap addresses */

  unsigned_word heap_base;

  unsigned_word heap_bound;

  unsigned_word heap_upper_limit;

} hw_vm_device;

static void

hw_vm_init_address_callback(device *me)

{

  hw_vm_device *vm = (hw_vm_device*)device_data(me);

  /* revert the stack/heap variables to their defaults */

  vm->stack_base = device_find_integer_property(me, "stack-base");

  vm->stack_bound = (vm->stack_base

                     + device_find_integer_property(me, "nr-bytes"));

  vm->stack_lower_limit = vm->stack_bound;

  vm->heap_base = 0;

  vm->heap_bound = 0;

  vm->heap_upper_limit = 0;

  /* establish this device as the default memory handler */

  device_attach_address(device_parent(me),

                        attach_callback + 1,

                        (((unsigned)0)-1) /*nr_bytes - ignore*/,

                        access_read_write /*access*/,

                        me);

}

static void

hw_vm_attach_address(device *me,

                     attach_type attach,

                     int space,

                     unsigned_word addr,

                     unsigned nr_bytes,

                     access_type access,

                     device *client) /*callback/default*/

{

  hw_vm_device *vm = (hw_vm_device*)device_data(me);

  /* update end of bss if necessary */

  if (vm->heap_base < addr + nr_bytes) {

    vm->heap_base = addr + nr_bytes;

    vm->heap_bound = addr + nr_bytes;

    vm->heap_upper_limit = addr + nr_bytes;

  }

  device_attach_address(device_parent(me),

                        attach_raw_memory,

                        addr,

                        nr_bytes,

                        access,

                        me);

}

static unsigned

hw_vm_add_space(device *me,

                unsigned_word addr,

                unsigned nr_bytes,

                cpu *processor,

                unsigned_word cia)

{

  hw_vm_device *vm = (hw_vm_device*)device_data(me);

  unsigned_word block_addr;

  unsigned block_nr_bytes;

  /* an address in the stack area, allocate just down to the addressed

     page */

  if (addr >= vm->stack_base && addr < vm->stack_lower_limit) {

    block_addr = FLOOR_PAGE(addr);

    block_nr_bytes = vm->stack_lower_limit - block_addr;

    vm->stack_lower_limit = block_addr;

  }

  /* an address in the heap area, allocate all of the required heap */

  else if (addr >= vm->heap_upper_limit && addr < vm->heap_bound) {

    block_addr = vm->heap_upper_limit;

    block_nr_bytes = vm->heap_bound - vm->heap_upper_limit;

    vm->heap_upper_limit = vm->heap_bound;

  }

  /* oops - an invalid address - abort the cpu */

  else if (processor != NULL) {

    cpu_halt(processor, cia, was_signalled, SIGSEGV);

    return 0;

  }

  /* 2*oops - an invalid address and no processor */

  else {

    return 0;

  }

  /* got the parameters, allocate the space */

  device_attach_address(device_parent(me),

                        attach_raw_memory,

                        block_addr,

                        block_nr_bytes,

                        access_read_write,

                        me);

  return block_nr_bytes;

}

static unsigned

hw_vm_io_read_buffer_callback(device *me,

                           void *dest,

                           int space,

                           unsigned_word addr,

                           unsigned nr_bytes,

                           cpu *processor,

                           unsigned_word cia)

{

  if (hw_vm_add_space(me, addr, nr_bytes, processor, cia) >= nr_bytes) {

    memset(dest, 0, nr_bytes); /* always initialized to zero */

    return nr_bytes;

  }

  else

    return 0;

}

static unsigned

hw_vm_io_write_buffer_callback(device *me,

                            const void *source,

                            int space,

                            unsigned_word addr,

                            unsigned nr_bytes,

                            cpu *processor,

                            unsigned_word cia)

{

  if (hw_vm_add_space(me, addr, nr_bytes, processor, cia) >= nr_bytes) {

    return device_dma_write_buffer(device_parent(me), source,

                                   space, addr,

                                   nr_bytes,

                                   0/*violate_read_only*/);

  }

  else

    return 0;

}

static int

hw_vm_ioctl(device *me,

            cpu *processor,

            unsigned_word cia,

            device_ioctl_request request,

            va_list ap)

{

  /* While the caller is notified that the heap has grown by the

     requested amount, the heap is actually extended out to a page

     boundary. */

  hw_vm_device *vm = (hw_vm_device*)device_data(me);

  switch (request) {

  case device_ioctl_break:

    {

      unsigned_word requested_break = va_arg(ap, unsigned_word);

      unsigned_word new_break = ALIGN_8(requested_break);

      unsigned_word old_break = vm->heap_bound;

      signed_word delta = new_break - old_break;

      if (delta > 0)

        vm->heap_bound = ALIGN_PAGE(new_break);

      break;

    }

  default:

    device_error(me, "Unsupported ioctl request");

    break;

  }

  return 0;

}

static device_callbacks const hw_vm_callbacks = {

  { hw_vm_init_address_callback, },

  { hw_vm_attach_address,

    passthrough_device_address_detach, },

  { hw_vm_io_read_buffer_callback,

    hw_vm_io_write_buffer_callback, },

  { NULL, passthrough_device_dma_write_buffer, },

  { NULL, }, /* interrupt */

  { generic_device_unit_decode,

    generic_device_unit_encode, },

  NULL, /* instance */

  hw_vm_ioctl,

};

static void *

hw_vm_create(const char *name,

             const device_unit *address,

             const char *args)

{

  hw_vm_device *vm = ZALLOC(hw_vm_device);

  return vm;

}

const device_descriptor hw_vm_device_descriptor[] = {

  { "vm", hw_vm_create, &hw_vm_callbacks },

  { NULL },

};

#endif /* _HW_VM_C_ */