Kernel - MMap fixed (non-fixed mappings, bad search), SHM mmap only working

[tpg/acess2.git] / KernelLand / Kernel / vfs / mmap.c

diff --git a/KernelLand/Kernel/vfs/mmap.c b/KernelLand/Kernel/vfs/mmap.c
index 9a7fa44..9016d56 100644 (file)
--- a/KernelLand/Kernel/vfs/mmap.c
+++ b/KernelLand/Kernel/vfs/mmap.c
@@ -10,6 +10,7 @@
 #include <vfs.h>
 #include <vfs_ext.h>
 #include <vfs_int.h>
+#include <mm_virt.h>   // MM_USER_MAX
 
 #define MMAP_PAGES_PER_BLOCK   16
 
@@ -27,17 +28,19 @@ struct sVFS_MMapPageBlock
 void   *VFS_MMap_Anon(void *Destination, size_t Length, Uint FlagsSet, Uint FlagsMask);
 int    VFS_MMap_MapPage(tVFS_Node *Node, unsigned int PageNum, tVFS_MMapPageBlock *pb, void *mapping_dest, unsigned int Protection);
 //int  VFS_MUnmap(void *Addr, size_t Length);
+bool   _range_free(const tPage *Base, Uint NumPages);
 
 // === CODE ===
 void *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset)
 {
-       ENTER("pDestHint iLength xProtection xFlags xFD XOffset", DestHint, Length, Protection, Flags, FD, Offset);
+       ENTER("pDestHint xLength xProtection xFlags xFD XOffset", DestHint, Length, Protection, Flags, FD, Offset);
 
        if( Flags & MMAP_MAP_ANONYMOUS )
                Offset = (tVAddr)DestHint & 0xFFF;
        
        unsigned int npages = ((Offset & (PAGE_SIZE-1)) + Length + (PAGE_SIZE - 1)) / PAGE_SIZE;
        unsigned int pagenum = Offset / PAGE_SIZE;
+       LOG("npages=%u,pagenum=%u", npages, pagenum);
 
        tVAddr mapping_base = (tVAddr)DestHint;
 
@@ -50,16 +53,38 @@ void *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD,
        else
        {
                Log_Warning("VFS", "MMap: TODO Handle non-fixed mappings");
-               if( DestHint == NULL )
+               
+               // Locate a free location in the address space (between brk and MM_USER_MAX)
+               // TODO: Prefer first location after DestHint, but can go below
+               
+               // Search downwards from the top of user memory
+               mapping_base = 0;
+               for( tPage *dst = (tPage*)MM_USER_MAX - npages; dst > (tPage*)PAGE_SIZE; dst -- )
+               {
+                       if( _range_free(dst, npages) ) {
+                               mapping_base = (tVAddr)dst;
+                               break;
+                       }
+               }
+               if( mapping_base == 0 )
                {
-                       // TODO: Locate space for the allocation
-                       Log_Warning("VFS", "Mmap: Handle NULL destination hint");
+                       Log_Warning("VFS", "MMap: Out of address space");
+                       errno = ENOMEM;
                        LEAVE('n');
                        return NULL;
                }
        }
        tPage   *mapping_dest = (void*)(mapping_base & ~(PAGE_SIZE-1));
 
+       if( !_range_free(mapping_dest, npages) )
+       {
+               LOG("Specified range is not free");
+               //errno = EINVAL;
+               //LEAVE('n');
+               //return NULL;
+               Log_Warning("VFS", "MMap: Overwriting/replacing maps at %p+%x", mapping_base, Length);
+       }
+
        // Handle anonymous mappings
        if( Flags & MMAP_MAP_ANONYMOUS )
        {
@@ -80,7 +105,7 @@ void *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD,
        // - Sorted list of 16 page blocks
        for( pb = h->Node->MMapInfo; pb; pb_pnp = &pb->Next, pb = pb->Next )
        {
-               if( pb->BaseOffset + MMAP_PAGES_PER_BLOCK <= pagenum )
+               if( pb->BaseOffset + MMAP_PAGES_PER_BLOCK > pagenum )
                        break;
        }
 
@@ -283,5 +308,19 @@ int VFS_MMap_MapPage(tVFS_Node *Node, unsigned int pagenum, tVFS_MMapPageBlock *
 
 int VFS_MUnmap(void *Addr, size_t Length)
 {
+       UNIMPLEMENTED();
        return 0;
 }
+
+bool _range_free(const tPage *Base, Uint NumPages)
+{
+       for( int i = 0; i < NumPages; i ++ )
+       {
+               if( MM_GetPhysAddr(Base + i) )
+               {
+                       // Oh.
+                       return false;
+               }
+       }
+       return true;
+}