copyvirtualspace.c

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/*****************************************************************************************
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 $Id: copyvirtualspace_8c-source.html 88 2016-01-12 00:11:29Z reddawg $

*****************************************************************************************/

#include <vmm/vmm.h>
#include <sys/kern_sysctl.h>
#include <ubixos/spinlock.h>
#include <ubixos/kpanic.h>
#include <string.h>

static spinLock_t cvsSpinLock = SPIN_LOCK_INITIALIZER;

/************************************************************************

Function: void *vmmCopyVirtualSpace(pidType pid);

Description: Creates A Copy Of A Virtual Space And Set All NON Kernel
             Space To COW For A Fork This Will Also Alter The Parents
             VM Space To Make That COW As Well

Notes:

08/02/02 - Added Passing Of pidType pid So We Can Better Keep Track Of
           Which Task Has Which Physical Pages

************************************************************************/
void           *
vmmCopyVirtualSpace(pidType pid)
{
  void           *newPageDirectoryAddress = 0x0;
  uInt32         *parentPageDirectory = 0x0, *newPageDirectory = 0x0;
  uInt32         *parentPageTable = 0x0, *newPageTable = 0x0;
  uInt32         *parentStackPage = 0x0, *newStackPage = 0x0;
  uInt16          x = 0, i = 0, s = 0;

  spinLock(&cvsSpinLock);
  
  /* Set Address Of Parent Page Directory */
  parentPageDirectory = (uInt32 *) parentPageDirAddr;
  /* Allocate A New Page For The New Page Directory */
  if ((newPageDirectory = (uInt32 *) vmmGetFreeKernelPage(pid,1)) == 0x0)
    kpanic("Error: newPageDirectory == NULL, File: %s, Line: %i\n",__FILE__,__LINE__);
    
  /* Set newPageDirectoryAddress To The Newly Created Page Directories Page */
  newPageDirectoryAddress = (void *)vmm_getPhysicalAddr((uInt32) newPageDirectory);
  
  /* First Set Up A Flushed Page Directory */
  memset(newPageDirectory,0x0,0x1000);

  /* Map The Top 1GB Region Of The VM Space */
  for (x = 768; x < pageEntries; x++) {
    newPageDirectory[x] = parentPageDirectory[x];
    }
    
  /*
   * Now For The Fun Stuff For Page Tables 1-766 We Must Map These And Set
   * The Permissions On Every Mapped Pages To COW This Will Conserve Memory
   * Because The Two VM Spaces Will Be Sharing Some Pages
   */
  for (x = 0x1; x <= 766; x++) {
    /* If Page Table Exists Map It */
    if (parentPageDirectory[x] != 0) {
      /* Set Parent  To Propper Page Table */
      parentPageTable = (uInt32 *) (tablesBaseAddress + (0x1000 * x));
      /* Allocate A New Page Table */
      if ((newPageTable = (uInt32 *) vmmGetFreeKernelPage(pid,1)) == 0x0)
        kpanic("Error: newPageTable == NULL, File: %s, Line: %i\n",__FILE__,__LINE__);

      /* Set Parent And New Pages To COW */
      for (i = 0; i < pageEntries; i++) {
      
        /* If Page Is Mapped */
        if ((parentPageTable[i] & 0xFFFFF000) != 0x0) {
          /* Check To See If Its A Stack Page */
          if (((uInt32) parentPageTable[i] & PAGE_STACK) == PAGE_STACK) {
            /* Alloc A New Page For This Stack Page */
            if ((newStackPage = (uInt32 *) vmmGetFreeKernelPage(pid,1)) == 0x0)
              kpanic("Error: newStackPage == NULL, File: %s, Line: %i\n",__FILE__,__LINE__);
              
            /* Set Pointer To Parents Stack Page */
            parentStackPage = (uInt32 *) (((1024 * 4096) * x) + (4096 * i));
            
            /* Copy The Tack Byte For Byte (I Should Find A Faster Way) */
            for (s = 0x0; s < pageEntries; s++) {
              newStackPage[s] = parentStackPage[s];
              }
            /* Insert New Stack Into Page Table */
            newPageTable[i] = (vmm_getPhysicalAddr((uInt32) newStackPage) | PAGE_DEFAULT | PAGE_STACK);
            /* Unmap From Kernel Space */
            vmmUnmapPage((uInt32) newStackPage, 1);
            }
          else {
            /* Set Page To COW In Parent And Child Space */
            newPageTable[i] = (((uInt32) parentPageTable[i] & 0xFFFFF000) | (PAGE_DEFAULT | PAGE_COW));
            /* Increment The COW Counter For This Page */
            if (((uInt32) parentPageTable[i] & PAGE_COW) == PAGE_COW) {
              adjustCowCounter(((uInt32) parentPageTable[i] & 0xFFFFF000), 1);
              }
            else {
              adjustCowCounter(((uInt32) parentPageTable[i] & 0xFFFFF000), 2);
              parentPageTable[i] = newPageTable[i];
              }
            }
          }
        else {
          newPageTable[i] = (uInt32) 0x0;
          }
        }

      /* Put New Page Table Into New Page Directory */
      newPageDirectory[x] = (vmm_getPhysicalAddr((uInt32) newPageTable) | PAGE_DEFAULT);
      /* Unmap Page From Kernel Space But Keep It Marked As Not Avail */
      vmmUnmapPage((uInt32) newPageTable, 1);
    } else {
      newPageDirectory[x] = (uInt32) 0x0;
    }
  }
  /*
   * Allocate A New Page For The The First Page Table Where We Will Map The
   * Lower Region
   */
  if ((newPageTable = (uInt32 *) vmmGetFreeKernelPage(pid,1)) == 0x0)
    kpanic("Error: newPageTable == NULL, File: %s, Line: %i\n",__FILE__,__LINE__);
    
  /* Flush The Page From Garbage In Memory */
  memset(newPageTable,0x0,0x1000);

  /* Map This Into The Page Directory */
  newPageDirectory[0] = (vmm_getPhysicalAddr((uInt32) newPageTable) | PAGE_DEFAULT);
  /* Set Address Of Parents Page Table */
  parentPageTable = (uInt32 *) tablesBaseAddress;
  /* Map The First 1MB Worth Of Pages */
  for (x = 0; x < (pageEntries / 4); x++) {
    newPageTable[x] = parentPageTable[x];
  }
  /* Map The Next 3MB Worth Of Pages But Make Them COW */
  for (x = (pageEntries / 4) + 1; x < pageEntries; x++) {
    /* If Page Is Avaiable Map It */
    if ((parentPageTable[x] & 0xFFFFF000) != 0x0) {
      /* Set Pages To COW */
      newPageTable[x] = (((uInt32) parentPageTable[x] & 0xFFFFF000) | (PAGE_DEFAULT | PAGE_COW));
      /* Increment The COW Counter For This Page */
      if (((uInt32) parentPageTable[x] & PAGE_COW) == PAGE_COW) {
        adjustCowCounter(((uInt32) parentPageTable[x] & 0xFFFFF000), 1);
      } else {
        adjustCowCounter(((uInt32) parentPageTable[x] & 0xFFFFF000), 2);
        parentPageTable[x] = newPageTable[x];
      }
    } else {
      newPageTable[x] = (uInt32) 0x0;
    }
  }
  /* Set Virtual Mapping For Page Directory */
  newPageTable[256] = (vmm_getPhysicalAddr((uInt32) newPageDirectory) | PAGE_DEFAULT);

  /*
   * Now The Fun Stuff Build The Initial Virtual Page Space So We Don't Have
   * To Worry About Mapping Them In Later How Ever I'm Concerned This May
   * Become A Security Issue
   */
  /* First Lets Unmap The Previously Allocated Page Table */
  vmmUnmapPage((uInt32) newPageTable, 1);
  /* Allocate A New Page Table */
  if ((newPageTable = (uInt32 *) vmmGetFreeKernelPage(pid,1)) == 0x0)
    kpanic("Error: newPageTable == NULL, File: %s, Line: %i\n",__FILE__,__LINE__);
  /* First Set Our Page Directory To Contain This */
  newPageDirectory[767] = vmm_getPhysicalAddr((uInt32) newPageTable) | PAGE_DEFAULT;
  /* Now Lets Build The Page Table */
  for (x = 0; x < pageEntries; x++) {
    newPageTable[x] = newPageDirectory[x];
  }
  /* Now We Are Done So Lets Unmap This Page */
  vmmUnmapPage((uInt32) newPageTable, 1);
  /* Now We Are Done With The Page Directory So Lets Unmap That Too */
  vmmUnmapPage((uInt32) newPageDirectory, 1);
  
  spinUnlock(&cvsSpinLock);
  
  /* Return Physical Address Of Page Directory */
  return (newPageDirectoryAddress);
}

/***
 $Log: copyvirtualspace_8c-source.html,v $
 Revision 1.7  2006/12/15 17:47:04  reddawg
 Updates

 Revision 1.4  2006/12/05 14:10:21  reddawg
 Workign Distro

 Revision 1.3  2006/12/01 05:12:35  reddawg
 We're almost there... :)

 Revision 1.2  2006/11/06 19:10:12  reddawg
 Lots Of Updates... Still having issues with brk();

 Revision 1.1.1.1  2006/06/01 12:46:13  reddawg
 ubix2

 Revision 1.2  2005/10/12 00:13:38  reddawg
 Removed

 Revision 1.1.1.1  2005/09/26 17:24:49  reddawg
 no message

 Revision 1.7  2004/07/28 15:05:43  reddawg
 Major:
   Pages now have strict security enforcement.
   Many null dereferences have been resolved.
   When apps loaded permissions set for pages rw and ro

 Revision 1.6  2004/07/26 19:15:49  reddawg
 test code, fixes and the like

 Revision 1.5  2004/07/25 06:04:00  reddawg
 Last of my fixes for the morning

 Revision 1.4  2004/07/20 22:29:55  reddawg
 assert: remade assert

 Revision 1.3  2004/07/19 01:58:12  reddawg
 vmmCopyVirtualSpace: cleaned up one full page memory leak we were still using old sysID over pid

 Revision 1.2  2004/06/15 12:35:05  reddawg
 Cleaned Up

 Revision 1.1.1.1  2004/04/15 12:06:51  reddawg
 UbixOS v1.0

 Revision 1.14  2004/04/13 16:36:34  reddawg
 Changed our copyright, it is all now under a BSD-Style license

 END
 ***/

---