Linking and MM Fiddling (mm now handles large pages - well, partially)

diff --git a/Kernel/arch/x86_64/link.ld b/Kernel/arch/x86_64/link.ld
index eb84fcd..f5e7355 100644 (file)
--- a/Kernel/arch/x86_64/link.ld
+++ b/Kernel/arch/x86_64/link.ld
@@ -34,8 +34,7 @@ SECTIONS {
        
        .rodata ALIGN(0x1000): AT(ADDR(.rodata) - _kernel_base) {
                *(.initpd)
-               *(.rodata)
-               *(.rodata.*)
+               *(.rodata .rodata.*)
                *(.rdata)
                
                . = ALIGN(0x10);

diff --git a/Kernel/arch/x86_64/mm_virt.c b/Kernel/arch/x86_64/mm_virt.c
index bc9e8f6..2605a86 100644 (file)
--- a/Kernel/arch/x86_64/mm_virt.c
+++ b/Kernel/arch/x86_64/mm_virt.c
@@ -23,6 +23,7 @@
 #define        PF_PRESENT      0x1
 #define        PF_WRITE        0x2
 #define        PF_USER         0x4
+#define        PF_LARGE        0x0
 #define        PF_COW          0x200
 #define        PF_PAGED        0x400
 #define        PF_NX           0x80000000##00000000
@@ -41,6 +42,7 @@ void  MM_FinishVirtualInit(void);
 void   MM_PageFault(tVAddr Addr, Uint ErrorCode, tRegs *Regs);
 void   MM_DumpTables(tVAddr Start, tVAddr End);
  int   MM_Map(tVAddr VAddr, tPAddr PAddr);
+ int   MM_GetPageEntry(tVAddr Addr, tPAddr *Phys, Uint *Flags);
 
 // === GLOBALS ===
 
@@ -226,16 +228,25 @@ int MM_Map(tVAddr VAddr, tPAddr PAddr)
        
        ENTER("xVAddr xPAddr", VAddr, PAddr);
        
+       // Check that the page hasn't been mapped already
+       {
+               Uint    flags;
+                int    ret;
+               ret = MM_GetPageEntry(VAddr, &tmp, &flags);
+               if( flags & PF_PRESENT ) {
+                       LEAVE('i', 0);
+                       return 0;
+               }
+       }
+       
        // Check PML4
-       //Log(" MM_Map: &PAGEMAPLVL4(%x) = %x", VAddr >> 39, &PAGEMAPLVL4(VAddr >> 39));
-       //Log(" MM_Map: &PAGEDIRPTR(%x) = %x", VAddr >> 30, &PAGEDIRPTR(VAddr >> 30));
-       //Log(" MM_Map: &PAGEDIR(%x) = %x", VAddr >> 21, &PAGEDIR(VAddr >> 21));
-       //Log(" MM_Map: &PAGETABLE(%x) = %x", VAddr >> 12, &PAGETABLE(VAddr >> 12));
-       //Log(" MM_Map: &PAGETABLE(0) = %x", &PAGETABLE(0));
        if( !(PAGEMAPLVL4(VAddr >> 39) & 1) )
        {
                tmp = MM_AllocPhys();
-               if(!tmp)        return 0;
+               if(!tmp) {
+                       LEAVE('i', 0);
+                       return 0;
+               }
                PAGEMAPLVL4(VAddr >> 39) = tmp | 3;
                INVLPG( &PAGEDIRPTR( (VAddr>>39)<<9 ) );
                memset( &PAGEDIRPTR( (VAddr>>39)<<9 ), 0, 4096 );
@@ -245,7 +256,10 @@ int MM_Map(tVAddr VAddr, tPAddr PAddr)
        if( !(PAGEDIRPTR(VAddr >> 30) & 1) )
        {
                tmp = MM_AllocPhys();
-               if(!tmp)        return 0;
+               if(!tmp) {
+                       LEAVE('i', 0);
+                       return 0;
+               }
                PAGEDIRPTR(VAddr >> 30) = tmp | 3;
                INVLPG( &PAGEDIR( (VAddr>>30)<<9 ) );
                memset( &PAGEDIR( (VAddr>>30)<<9 ), 0, 0x1000 );
@@ -255,15 +269,20 @@ int MM_Map(tVAddr VAddr, tPAddr PAddr)
        if( !(PAGEDIR(VAddr >> 21) & 1) )
        {
                tmp = MM_AllocPhys();
-               if(!tmp)        return 0;
+               if(!tmp) {
+                       LEAVE('i', 0);
+                       return 0;
+               }
                PAGEDIR(VAddr >> 21) = tmp | 3;
                INVLPG( &PAGETABLE( (VAddr>>21)<<9 ) );
                memset( &PAGETABLE( (VAddr>>21)<<9 ), 0, 4096 );
        }
        
        // Check if this virtual address is already mapped
-       if( PAGETABLE(VAddr >> PTAB_SHIFT) & 1 )
+       if( PAGETABLE(VAddr >> PTAB_SHIFT) & 1 ) {
+               LEAVE('i', 0);
                return 0;
+       }
        
        PAGETABLE(VAddr >> PTAB_SHIFT) = PAddr | 3;
        
@@ -340,21 +359,79 @@ void MM_Deallocate(tVAddr VAddr)
        MM_DerefPhys(phys);
 }
 
+/**
+ * \brief Get the page table entry of a virtual address
+ * \param Addr Virtual Address
+ * \param Phys Location to put the physical address
+ * \param Flags        Flags on the entry (set to zero if unmapped)
+ * \return Size of the entry (in address bits) - 12 = 4KiB page
+ */
+int MM_GetPageEntry(tVAddr Addr, tPAddr *Phys, Uint *Flags)
+{
+       if(!Phys || !Flags)     return 0;
+       
+       // Check if the PML4 entry is present
+       if( !(PAGEMAPLVL4(Addr >> 39) & 1) ) {
+               *Phys = 0;
+               *Flags = 0;
+               return 39;
+       }
+       // - Check for large page
+       if( PAGEMAPLVL4(Addr >> 39) & PF_LARGE ) {
+               *Phys = PAGEMAPLVL4(Addr >> 39) & ~0xFFF;
+               *Flags = PAGEMAPLVL4(Addr >> 39) & 0xFFF;
+               return 39;
+       }
+       
+       // Check the PDP entry
+       if( !(PAGEDIRPTR(Addr >> 30) & 1) ) {
+               *Phys = 0;
+               *Flags = 0;
+               return 30;
+       }
+       // - Check for large page
+       if( PAGEDIRPTR(Addr >> 30) & PF_LARGE ) {
+               *Phys = PAGEDIRPTR(Addr >> 30) & ~0xFFF;
+               *Flags = PAGEDIRPTR(Addr >> 30) & 0xFFF;
+               return 30;
+       }
+       
+       // Check PDIR Entry
+       if( !(PAGEDIR(Addr >> 21) & 1) ) {
+               *Phys = 0;
+               *Flags = 0;
+               return 21;
+       }
+       // - Check for large page
+       if( PAGEDIR(Addr >> 21) & PF_LARGE ) {
+               *Phys = PAGEDIR(Addr >> 21) & ~0xFFF;
+               *Flags = PAGEDIR(Addr >> 21) & 0xFFF;
+               return 21;
+       }
+       
+       // And, check the page table entry
+       if( !(PAGETABLE(Addr >> PTAB_SHIFT) & 1) ) {
+               *Phys = 0;
+               *Flags = 0;
+       }
+       else {
+               *Phys = PAGETABLE(Addr >> PTAB_SHIFT) & ~0xFFF;
+               *Flags = PAGETABLE(Addr >> PTAB_SHIFT) & 0xFFF;
+       }
+       return 12;
+}
+
 /**
  * \brief Get the physical address of a virtual location
  */
 tPAddr MM_GetPhysAddr(tVAddr Addr)
 {
-       if( !(PAGEMAPLVL4(Addr >> 39) & 1) )
-               return 0;
-       if( !(PAGEDIRPTR(Addr >> 30) & 1) )
-               return 0;
-       if( !(PAGEDIR(Addr >> 21) & 1) )
-               return 0;
-       if( !(PAGETABLE(Addr >> PTAB_SHIFT) & 1) )
-               return 0;
+       tPAddr  ret;
+       Uint    flags;
+       
+       MM_GetPageEntry(Addr, &ret, &flags);
        
-       return (PAGETABLE(Addr >> PTAB_SHIFT) & ~0xFFF) | (Addr & 0xFFF);
+       return ret | (Addr & 0xFFF);
 }
 
 /**
@@ -577,7 +654,7 @@ tVAddr MM_NewKStack(void)
                if(MM_GetPhysAddr(base) != 0)
                        continue;
                
-               Log("MM_NewKStack: Found one at %p", base + KERNEL_STACK_SIZE);
+               //Log("MM_NewKStack: Found one at %p", base + KERNEL_STACK_SIZE);
                for( i = 0; i < KERNEL_STACK_SIZE; i += 0x1000)
                        MM_Allocate(base+i);