PageEntry SectionMethodList::GetPageListEntry(UInt32 idx)
{
ASSERT(idx < m_uPageListCountDEBUG);
if (m_uFlags & SmallPageListEntriesFlag)
return PageEntry(dac_cast<ArrayDPTR(UInt16)>(m_pbPageList)[idx]);
return PageEntry((dac_cast<PTR_UInt32>(m_pbPageList))[idx]);
}
PageTable MMU::getOrCreateTable(uint16_t directoryIndex)
{
if (directoryIndex > 1023) {
kernel->panic("MMU::getOrCreateTable: invalid directoryIndex");
}
PageEntry pde = _pageDirectory.entryAtIndex(directoryIndex);
PageTable table{PageTableForDirectoryIndex(directoryIndex)};
if (!pde.getFlag(kPresentBit)) { // no page table here, create one
pde = PageEntry(_pageFrameAllocator.alloc());
pde.setFlags(kPresentBit | kReadWriteBit);
_pageDirectory.setEntry(directoryIndex, pde);
table.clear();
_flush();
}
return table;
}
int MMU::pfree(void *startOfMemoryRange, size_t numberOfPages)
{
uint32_t virtualAddress = (uint32_t) startOfMemoryRange;
if (!numberOfPages) return -1;
while (numberOfPages--) {
uint32_t pdeIndex = virtualAddress >> 22;
uint32_t pteIndex = virtualAddress >> 12 & 0x03FF;
PageTable table = PageTableForDirectoryIndex(pdeIndex);
PageEntry pte = table.entryAtIndex(pteIndex);
_pageFrameAllocator.free(pte.address());
table.setEntry(pteIndex, PageEntry(0));
virtualAddress += 0x1000;
}
_flush();
return 0;
}
void MMU::allocatePages(void *address, size_t numberOfPages)
{
uintptr_t virtualAddress = reinterpret_cast<uintptr_t>(address);
uint32_t currpde = virtualAddress >> 22;
uint32_t currpte = virtualAddress >> 12 & 0x03FF;
size_t pagesLeft = numberOfPages;
while (pagesLeft > 0) { // map the pages
PageTable table = PageTableForDirectoryIndex(currpde);
PageEntry entry = PageEntry(_pageFrameAllocator.alloc());
entry.setFlags(kPresentBit | kReadWriteBit);
table.setEntry(currpte, entry);
++currpte;
--pagesLeft;
// move to next PDE if needed
if (currpte > 1023) {
++currpde;
currpte = 0;
}
}
_flush();
}
