X-Git-Url: https://git.ucc.asn.au/?a=blobdiff_plain;f=Kernel%2Farch%2Fx86%2Fmm_virt.c;h=a022da2b9e9f92f24b414e520d1051eb2b7e11fa;hb=df4e449c0972a703ce403332668a7bb3366d126a;hp=b4fd2225a3d90616c3c7d4883efb8f137ff4a0a7;hpb=cf00ee7fb53960fabd8b3c1072a54605118adf9c;p=tpg%2Facess2.git

diff --git a/Kernel/arch/x86/mm_virt.c b/Kernel/arch/x86/mm_virt.c
index b4fd2225..a022da2b 100644
--- a/Kernel/arch/x86/mm_virt.c
+++ b/Kernel/arch/x86/mm_virt.c
@@ -28,8 +28,6 @@
 #define	TEMP_MAP_ADDR	0xFEFF0000	// Allows 16 "temp" pages
 #define	NUM_TEMP_PAGES	16
 
-#define	USE_COW	1
-
 #define	PF_PRESENT	0x1
 #define	PF_WRITE	0x2
 #define	PF_USER		0x4
@@ -99,7 +97,7 @@ void MM_InstallVirtual()
  */
 void MM_PageFault(Uint Addr, Uint ErrorCode, tRegs *Regs)
 {
-	ENTER("xAddr bErrorCode", Addr, ErrorCode);
+	//ENTER("xAddr bErrorCode", Addr, ErrorCode);
 	
 	// -- Check for COW --
 	if( gaPageDir  [Addr>>22] & PF_PRESENT
@@ -107,12 +105,20 @@ void MM_PageFault(Uint Addr, Uint ErrorCode, tRegs *Regs)
 	 && gaPageTable[Addr>>12] & PF_COW )
 	{
 		tPAddr	paddr;
-		paddr = MM_DuplicatePage( Addr );
-		MM_DerefPhys( gaPageTable[Addr>>12] & ~0xFFF );
-		gaPageTable[Addr>>12] &= PF_USER;
-		gaPageTable[Addr>>12] |= paddr|PF_PRESENT|PF_WRITE;
+		if(MM_GetRefCount( gaPageTable[Addr>>12] & ~0xFFF ) == 0)
+		{
+			gaPageTable[Addr>>12] &= ~PF_COW;
+			gaPageTable[Addr>>12] |= PF_PRESENT|PF_WRITE;
+		}
+		else
+		{
+			paddr = MM_DuplicatePage( Addr );
+			MM_DerefPhys( gaPageTable[Addr>>12] & ~0xFFF );
+			gaPageTable[Addr>>12] &= PF_USER;
+			gaPageTable[Addr>>12] |= paddr|PF_PRESENT|PF_WRITE;
+		}
 		INVLPG( Addr & ~0xFFF );
-		LEAVE('-');
+		//LEAVE('-')
 		return;
 	}
 	
@@ -136,7 +142,6 @@ void MM_PageFault(Uint Addr, Uint ErrorCode, tRegs *Regs)
 	MM_DumpTables(0, -1);	
 	
 	Panic("Page Fault at 0x%x\n", Regs->eip);
-	LEAVE('-');
 }
 
 /**
@@ -200,11 +205,18 @@ void MM_DumpTables(tVAddr Start, tVAddr End)
  */
 tPAddr MM_Allocate(Uint VAddr)
 {
+	tPAddr	paddr;
 	// Check if the directory is mapped
 	if( gaPageDir[ VAddr >> 22 ] == 0 )
 	{
 		// Allocate directory
-		gaPageDir[ VAddr >> 22 ] = MM_AllocPhys() | 3;
+		paddr = MM_AllocPhys();
+		if( paddr == 0 ) {
+			Warning("MM_Allocate - Out of Memory (Called by %p)", __builtin_return_address(0));
+			return 0;
+		}
+		// Map
+		gaPageDir[ VAddr >> 22 ] = paddr | 3;
 		// Mark as user
 		if(VAddr < MM_USER_MAX)	gaPageDir[ VAddr >> 22 ] |= PF_USER;
 		
@@ -213,18 +225,25 @@ tPAddr MM_Allocate(Uint VAddr)
 	}
 	// Check if the page is already allocated
 	else if( gaPageTable[ VAddr >> 12 ] != 0 ) {
-		Warning("MM_Allocate - Allocating to used address");
+		Warning("MM_Allocate - Allocating to used address (%p)", VAddr);
 		return gaPageTable[ VAddr >> 12 ] & ~0xFFF;
 	}
 	
 	// Allocate
-	gaPageTable[ VAddr >> 12 ] = MM_AllocPhys() | 3;
+	paddr = MM_AllocPhys();
+	if( paddr == 0 ) {
+		Warning("MM_Allocate - Out of Memory when allocating at %p (Called by %p)",
+			VAddr, __builtin_return_address(0));
+		return 0;
+	}
+	// Map
+	gaPageTable[ VAddr >> 12 ] = paddr | 3;
 	// Mark as user
 	if(VAddr < MM_USER_MAX)	gaPageTable[ VAddr >> 12 ] |= PF_USER;
 	// Invalidate Cache for address
 	INVLPG( VAddr & ~0xFFF );
 	
-	return gaPageTable[ VAddr >> 12 ] & ~0xFFF;
+	return paddr;
 }
 
 /**
@@ -393,7 +412,6 @@ Uint MM_Clone()
 				continue;
 			}
 			
-			#if USE_COW
 			// Refrence old page
 			MM_RefPhys( gaPageTable[i*1024+j] & ~0xFFF );
 			// Add to new table
@@ -403,10 +421,6 @@ Uint MM_Clone()
 			}
 			else
 				gaTmpTable[i*1024+j] = gaPageTable[i*1024+j];
-			LOG("gaTmpTable[0x%x] = 0x%x", i*1024+j, gaTmpTable[i*1024+j]);
-			#else
-			gaTmpTable[i*1024+j] = MM_DuplicatePage( (i*1024+j)<<12 ) | (gaPageTable[i*1024+j]&7);
-			#endif
 		}
 	}
 	
@@ -524,6 +538,19 @@ void MM_SetFlags(Uint VAddr, Uint Flags, Uint Mask)
 		if( Flags & MM_PFLAG_KERNEL )	*ent &= ~PF_USER;
 		else	*ent |= PF_USER;
 	}
+	
+	// Copy-On-Write
+	if( Mask & MM_PFLAG_COW )
+	{
+		if( Flags & MM_PFLAG_COW ) {
+			*ent &= ~PF_WRITE;
+			*ent |= PF_COW;
+		}
+		else {
+			*ent &= ~PF_COW;
+			*ent |= PF_WRITE;
+		}
+	}
 }
 
 /**