vm.c

一个微型操作系统源码

/** vm.c
 **
 ** Description:
 ** Virtual Memory Management - regions
 ** based ot Roadrunner/pk vm code
 **
 **/

#include <asm/system.h> /* for flush_tlb() */
#include <asm/io.h>
#include <asm/errno.h>
#include <string.h>	/* bzero() etc. */
#include <mm.h> 

void vmMapInit(pagedir *pd, ulong pages)
{
   int   i;
   pagetable *pde = NULL;

   bzero(pd, sizeof(pagedir));
   for (i=0; i < pages; i++) {
      if ((i & 0x3ff) == 0) {
         /* PageDir entry absolute address */
         pde = (pagetable *) ((ulong)pd  + ((i>>10) + 1) * PAGE_SIZE);
         bzero(pde, sizeof(pagetable));
         make_pde(pd, i>>10, (ulong)pde >> PAGE_SHIFT,VMM_FREE);
      }
      make_pte(pde, i & 0x3ff, i, VMM_FREE);
   }
   flush_tlb();
}


int vmMap(pagedir *pd, void *page, ulong attr)
{
   pagetable *pde;
   int   idx;
   ulong addr,pte;

   if (pd == NULL || page == NULL) return EINVAL;

   /* get table entry. PDE_SHIFT = 22 */
   idx = (int) (((ulong)page >> PDE_SHIFT) & PAGE_MASK);
   pde = (pagetable *)((pd->entry[idx].address) << PAGE_SHIFT);

   /* get page entry. PTE_SHIFT = 12 */
   idx = (int) (((ulong)page >> PTE_SHIFT) & PAGE_MASK);
   addr = (ulong)(pde->entry[idx].address);
   pte = (ulong)page >> PAGE_SHIFT;

   if (addr == pte) return 0; 
   if (addr != 0L) return EPERM; /* already mapped */
   
   make_pte(pde,idx,pte,attr);
   return 0;
}


int vmUnmap(pagedir *pd, void *page)
{
   pagetable *pde;
   int   idx;
   ulong addr,pte;

   if (pd == NULL || page == NULL) return EINVAL;

   /* get table entry. PDE_SHIFT = 22 */
   idx = (int) (((ulong)page >> PDE_SHIFT) & PAGE_MASK);
   pde = (pagetable *)((pd->entry[idx].address) << PAGE_SHIFT);

   /* get page entry. PTE_SHIFT = 12 */
   idx = (int) (((ulong)page >> PTE_SHIFT) & PAGE_MASK);
   addr = (ulong)(pde->entry[idx].address);
   pte = (ulong)page >> PAGE_SHIFT;

   if (addr != pte) {
#ifdef DEBUG
   kprintf("unmap: pde=0x%08lx, idx=%ld, addr=0x%08lx, page=0x%08lx(0x%08lx)\n",
              pde,idx,addr,page,pte);
#endif      
      return EPERM;
   }

   make_pte(pde,idx,(ulong)0,VMM_FREE);

   return 0;
}


int vmMapRange(pagedir *pd, void *start, size_t len, ulong attr)
{
   ulong  addr, end;
   int    result;
   size_t length;

   length = PAGE_ROUND_UP(len);
   addr = (ulong) start;
   end = addr + length;

   for (; addr < end; addr += PAGE_SIZE)
      if ((result = vmMap(pd, (void *) addr, attr)) > 0)
         return result;
#ifdef DEBUG
/*      kprintf("Map Range: 0x%08lx - 0x%08lx (%ld)\n",
              start,end,length); */
#endif
   return 0;
}


int vmUnmapRange(pagedir *pd, void *start, size_t len)
{
   ulong  addr, end;
   size_t length;
   int    result;

   length = PAGE_ROUND_UP(len);
   addr = (ulong) start;
   end = addr + length;
   for (; addr < end; addr += PAGE_SIZE)
      if ((result = vmUnmap(pd, (void *) addr)) > 0)
         return result;
#ifdef DEBUG
/*      kprintf("UnMap Range: 0x%08lx - 0x%08lx (%ld)\n",
              start,end,length); */
#endif
   return 0;
}


#ifdef DEBUG
void dumpPageDir(pagedir *pd, ulong pdes)
{
   int i, j, idx;
   ulong addr;

   idx = 0;
   for (i=0;i<16;i++) {
      for (j=0;j<6;j++) {
         addr = (ulong)(pd->entry[idx].address);
         kprintf("%08lx  ",addr);
         idx++;
         if (idx > pdes) { kprintf("\n"); return; }
      }
      kprintf("\n");
   }
}

#endif

int vmKernelMap(pagedir *pd)
{
   int result;
   extern void _end;
   if ((result = vmMapRange(pd,
        (void *)PAGING_CR3,
        PAGE_ROUND_UP((ulong)&_end-PAGING_CR3),
        VMM_BUSY))>0) {
#ifdef DEBUG
      kprintf("[!!!] Kernel Memory Map Problem: %ld\n",result);
#endif
      return result;
   }
   return 0;
}