mem.c

Simple Operating Systems （简称SOS）是一个可以运行在X86平台上（包括QEMU

/* Copyright (C) 2005 David Decotigny

   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. 
*/

#include <sos/assert.h>
#include <sos/kmalloc.h>
#include <sos/physmem.h>
#include <hwcore/paging.h>
#include <sos/kmem_slab.h>
#include <sos/list.h>
#include <hwcore/paging.h>

#include "mem.h"


/**
 * A mapped mem/kmem resource
 */
struct kernel_remapped_resource
{
  int ref_cnt;
  struct sos_umem_vmm_mapped_resource mr;
};


/** Called after the virtual region has been inserted inside its
    address space */
static void resource_ref(struct sos_umem_vmm_vr * vr)
{
  /* Retrieve the mem/kmem structure associated with the mapped resource */
  struct kernel_remapped_resource * resource;
  resource
    = (struct kernel_remapped_resource*)
    sos_umem_vmm_get_mapped_resource_of_vr(vr)->custom_data;

  /* Increment ref counter */
  resource->ref_cnt ++;
}


/** Called when the virtual region is removed from its address
    space */
static void resource_unref(struct sos_umem_vmm_vr * vr)
{
  /* Retrieve the mem/kmem structure associated with the mapped resource */
  struct kernel_remapped_resource * resource;
  resource
    = (struct kernel_remapped_resource*)
    sos_umem_vmm_get_mapped_resource_of_vr(vr)->custom_data;
  
  /* Decrement ref coutner */
  SOS_ASSERT_FATAL(resource->ref_cnt > 0);
  resource->ref_cnt --;

  /* Free the resource if it becomes unused */
  if (resource->ref_cnt == 0)
    sos_kfree((sos_vaddr_t)resource);
}


/** MOST IMPORTANT callback ! Called when a thread page faults on the
    resource's mapping */
static sos_ret_t kmem_page_in(struct sos_umem_vmm_vr * vr,
			      sos_uaddr_t uaddr,
			      sos_bool_t write_access)
{
  sos_vaddr_t vaddr;
  sos_ret_t retval = SOS_OK;
  sos_paddr_t ppage_paddr;

  /* Compute address of kernel page */
  vaddr = uaddr - sos_umem_vmm_get_start_of_vr(vr)
    + sos_umem_vmm_get_offset_in_resource(vr);

  /* Don't allow demand paging of non kernel pages */
  if (vaddr >= SOS_PAGING_BASE_USER_ADDRESS)
    return -SOS_EFAULT;

  /* Lookup physical kernel page */
  ppage_paddr = sos_paging_get_paddr(SOS_PAGE_ALIGN_INF(vaddr));

  /* Cannot access unmapped kernel pages */
  if (! ppage_paddr)
    return -SOS_EFAULT;
  
  /* Remap it in user space */
  retval = sos_paging_map(ppage_paddr,
			  SOS_PAGE_ALIGN_INF(uaddr),
			  TRUE,
			  sos_umem_vmm_get_prot_of_vr(vr));

  return retval;
}


/** The callbacks for a mapped kmem resource */
static struct sos_umem_vmm_vr_ops kmem_ops = (struct sos_umem_vmm_vr_ops)
{
  .ref     = resource_ref,
  .unref   = resource_unref,
  .page_in = kmem_page_in,
};


/** The callback that gets called when the resource gets mapped */
static sos_ret_t kmem_mmap(struct sos_umem_vmm_vr *vr)
{
  return sos_umem_vmm_set_ops_of_vr(vr, &kmem_ops);
}


/** The function responsible for mapping the /dev/kmem resource in
    user space */
sos_ret_t sos_dev_kmem_map(struct sos_umem_vmm_as * dest_as,
			   sos_uaddr_t *uaddr,
			   sos_size_t size,
			   sos_vaddr_t offset,
			   sos_ui32_t access_rights,
			   sos_ui32_t flags)
{
  sos_ret_t retval;
  struct kernel_remapped_resource * kmem_resource;

  /* Allocate a new "descriptor" for the resource */
  kmem_resource
    = (struct kernel_remapped_resource*) sos_kmalloc(sizeof(*kmem_resource),
						     0);
  if (! kmem_resource)
    return -SOS_ENOMEM;

  memset(kmem_resource, 0x0, sizeof(*kmem_resource));
  kmem_resource->mr.allowed_access_rights 
    = SOS_VM_MAP_PROT_READ
    | SOS_VM_MAP_PROT_WRITE
    | SOS_VM_MAP_PROT_EXEC;
  kmem_resource->mr.custom_data    = kmem_resource;
  kmem_resource->mr.mmap           = kmem_mmap;

  /* Map it in user space */
  retval = sos_umem_vmm_map(dest_as, uaddr, size,
			    access_rights, flags,
			    & kmem_resource->mr, offset);
  if (SOS_OK != retval)
    {
      sos_kfree((sos_vaddr_t)kmem_resource);
      return retval;
    }

  return SOS_OK;
}


/** MOST IMPORTANT callback ! Called when a thread page faults on the
    resource's mapping */
static sos_ret_t physmem_page_in(struct sos_umem_vmm_vr * vr,
				 sos_uaddr_t uaddr,
				 sos_bool_t write_access)
{
  sos_ret_t retval = SOS_OK;
  sos_paddr_t ppage_paddr;

  /* Compute address of kernel page */
  ppage_paddr = uaddr - sos_umem_vmm_get_start_of_vr(vr)
    + sos_umem_vmm_get_offset_in_resource(vr);

  /* Remap page in user space */
  retval = sos_paging_map(SOS_PAGE_ALIGN_INF(ppage_paddr),
			  SOS_PAGE_ALIGN_INF(uaddr),
			  TRUE,
			  sos_umem_vmm_get_prot_of_vr(vr));
  return retval;
}


/** The callbacks for a mapped physmem resource */
static struct sos_umem_vmm_vr_ops physmem_ops = (struct sos_umem_vmm_vr_ops)
{
  .ref     = resource_ref,
  .unref   = resource_unref,
  .page_in = physmem_page_in,
};


/** The callback that gets called when the resource gets mapped */
static sos_ret_t physmem_mmap(struct sos_umem_vmm_vr *vr)
{
  return sos_umem_vmm_set_ops_of_vr(vr, &physmem_ops);
}


/** The function responsible for mapping the /dev/mem resource in
    user space */
sos_ret_t sos_dev_physmem_map(struct sos_umem_vmm_as * dest_as,
			      sos_uaddr_t *uaddr,
			      sos_size_t size,
			      sos_paddr_t offset,
			      sos_ui32_t access_rights,
			      sos_ui32_t flags)
{
  sos_ret_t retval;
  struct kernel_remapped_resource * physmem_resource;

  physmem_resource
    = (struct kernel_remapped_resource*) sos_kmalloc(sizeof(*physmem_resource),
						     0);
  if (! physmem_resource)
    return -SOS_ENOMEM;

  memset(physmem_resource, 0x0, sizeof(*physmem_resource));
  physmem_resource->mr.allowed_access_rights 
    = SOS_VM_MAP_PROT_READ
    | SOS_VM_MAP_PROT_WRITE
    | SOS_VM_MAP_PROT_EXEC;
  physmem_resource->mr.custom_data    = physmem_resource;
  physmem_resource->mr.mmap           = physmem_mmap;

  retval = sos_umem_vmm_map(dest_as, uaddr, size,
			    access_rights, flags,
			    & physmem_resource->mr, offset);
  if (SOS_OK != retval)
    {
      sos_kfree((sos_vaddr_t)physmem_resource);
      return retval;
    }

  return SOS_OK;
}