/**************************************************************************************
 Copyright (c) 2002
      The UbixOS Project

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WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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 $Id: pagefault.c,v 1.1 2003/04/20 12:11:30 reddawg Exp $
**************************************************************************************/

#include <vmm/paging.h>
#include <vmm/memory.h>
#include <ubixos/schedule.h>
#include <ubixos/panic.h>
#include <sys/video.h>

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

Function: void pageFault();
Description: This Function Is The Second Half Of The Page Fault ISR
             Currently It Handles COW However I Need To Prepar It For
             Swapping
Notes:

07/30/02 - Fixed COW However I Need To Think Of A Way To Impliment
           A Paging System Also Start To Add Security Levels

************************************************************************/
void pageFault() {
  uLong memAddr = 0,i = 0, pageTableIndex = 0,pageDirectoryIndex = 0;
  uLong *pageDir,*pageTable;
  uLong *src,*dst;
  pageDir = (uLong *)parentPageDirAddr;
  //Get Memory Address For Violation
  asm(
    "movl %%cr2,%%eax\n"
    "movl %%eax,%0\n"

    : "=g" (memAddr)
    );
  //Calculate The Page Directory Index
  pageDirectoryIndex = (memAddr/(1024*4096));
  //Calculate The Page Table Index
  pageTableIndex = ((memAddr-(pageDirectoryIndex*(1024*4096)))/4096);
  if (pageDir[pageDirectoryIndex] == 0) {
    //Creat A Routine For Non Mapped Memory
    kprintf("Segfault At Address: [0x%X][0x%X][%i]\n",memAddr,_current->tss.esp,_current->id);
    if ((uInt32)_current->tss.cr3 != (uInt32)kernelPageDirectory) {
      freeProcessPages(_current->id);
      }
    setTaskStatus(_current->id,EXITING);
    if (_current->id <= -1) {
      //kPanic("Kernel Crashed.\n");
      }
    schedule();
    while (1);
    }
  else {
    //Set pageTable To Point To Virtual Address Of Page Table
    pageTable = (uLong *)(tablesBaseAddress + (4096 * pageDirectoryIndex));
    if (((uLong)pageTable[pageTableIndex] & pageCow) == pageCow) {
      //Set Src To Base Address Of Page To Copy
      src = (uLong *) ((1024*4096*pageDirectoryIndex) + (4096*pageTableIndex));
      //Allocate A Free Page For Destination
      dst = (uLong *) getFreePage(-1);
      //Copy Memory
      for (i=0;i<pageEntries;i++) {
        dst[i] = src[i];
        }
      //Adjust The COW Counter For Physical Page
      adjustCowCounter(((uLong)pageTable[pageTableIndex] & 0xFFFFF000),-1);
      //Remap In New Page
      pageTable[pageTableIndex] = (uLong)((uLong)getPhysicalAddr((uLong)dst)|pageDefault);
      //Unlink From Memory Map Allocated Page
      unmapPage((uLong)dst,1);
      }
    else {
      //Need To Create A Routine For Attempting To Access Non Mapped Memory
      kprintf("Segfault At Address: [0x%X][0x%X][%i] Non Mapped\n",memAddr,_current->tss.esp,_current->id);
      /*
      kprintf("EAX:    [0x%X],EBX:    [0x%X]\n",_current->tss.eax,_current->tss.ebx);
      kprintf("ECX:    [0x%X],EDX:    [0x%X]\n",_current->tss.ecx,_current->tss.edx);
      kprintf("ESP:    [0x%X],EPB:    [0x%X]\n",_current->tss.esp,_current->tss.ebp);
      kprintf("EIP:    [0x%X],CR2:    [0x%X]\n",_current->tss.eip,memAddr);
      kprintf("CS:     [0x%X],DS:     [0x%X]\n",_current->tss.cs,_current->tss.ds);
      kprintf("SS:     [0x%X],ES:     [0x%X]\n",_current->tss.ss,_current->tss.es);
      kprintf("FS:     [0x%X],GS:     [0x%X]\n",_current->tss.gs,_current->tss.gs);
      kprintf("EFLAGS: [0x%X]         \n",_current->tss.eflags);
      */

      if ((uInt32)_current->tss.cr3 != (uInt32)kernelPageDirectory) {
        freeProcessPages(_current->id);
        }
      setTaskStatus(_current->id,EXITING);
      if (_current->id <= -1) {
        panic();
        }
      schedule();
      while(1);
      }
    }
  asm(
    "movl %cr3,%eax\n"
    "movl %eax,%cr3\n"
    );
  }

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

Function: void _pageFault()
Description: This Is The ASM Code That Calls The pageFault() Function
Notes:

************************************************************************/
asm(
    ".global _pageFault  \n"
    "_pageFault:         \n"
    "xchgl %eax,(%esp)   \n"
    "pushl %ecx          \n"
    "pushl %edx          \n"
    "push %ds            \n"
    "push %es            \n"
    "push %fs            \n"
    "call pageFault      \n"
    "pop %fs             \n"
    "pop %es             \n"
    "pop %ds             \n"
    "popl %edx           \n"
    "popl %ecx           \n"
    "popl %eax           \n"
    "iret                \n"
    );