Function MapTitlePhysicalPages

projects/WinDurango.KernelX/src/kernelx.cpp:497–543

    // Mappable memory requires special handling because of placeholder splits.
    // VirtualProtect will normally only work on pages that belong to the same allocation.
    if (AllocationBase)
    {
        // TODO: Validate all pages are committed before changing protections
        ULONG_PTR PageSize = Mappable.Is4MBPages ? PAGE_SIZE_2MB : PAGE_SIZE_4KB;
        ULONG_PTR BasePage = (ULONG_PTR)lpAddress & ~(PageSize - 1);
        ULONG_PTR LastPage = ((ULONG_PTR)lpAddress + dwSize) & ~(PageSize - 1);
        BOOL Status = VirtualProtectEx(hProcess, (LPVOID)BasePage, PageSize, flNewProtect,
                                       lpflOldProtect ? lpflOldProtect : &flOldProtect);

        for (ULONG_PTR Page = BasePage + PageSize; Page <= LastPage; Page += PageSize)
            Status |= VirtualProtectEx(hProcess, (LPVOID)Page, PageSize, flNewProtect, &flOldProtect);

        return Status;
    }

    return VirtualProtectEx(hProcess, lpAddress, dwSize, flNewProtect, lpflOldProtect ? lpflOldProtect : &flOldProtect);
}

EXTERN_C BOOL __stdcall EraVirtualProtect(LPVOID lpAddress, SIZE_T dwSize, DWORD flNewProtect, PDWORD lpflOldProtect)
{
    return EraVirtualProtectEx(GetCurrentProcess(), lpAddress, dwSize, flNewProtect, lpflOldProtect);
}

EXTERN_C PVOID __stdcall MapTitlePhysicalPages(PVOID VirtualAddress, ULONG_PTR NumberOfPages, DWORD flAllocationType,
                                               DWORD flProtect, PULONG_PTR PageArray)
{
    // TODO: Validate that PageArray contains contiguous 4MB blocks of 64K pages for MEM_4MB_PAGES

    if (!PageArray || (flAllocationType & (MEM_LARGE_PAGES | MEM_4MB_PAGES)) == 0 ||
        (flAllocationType & (MEM_LARGE_PAGES | MEM_4MB_PAGES)) == (MEM_LARGE_PAGES | MEM_4MB_PAGES) ||
        ((flAllocationType & MEM_4MB_PAGES) && (NumberOfPages & 63)))
    {
        SetLastError(ERROR_INVALID_PARAMETER);
        return nullptr;
    }

    ULONG_PTR dwPageSize = (flAllocationType & MEM_LARGE_PAGES) ? PAGE_SIZE_64K : PAGE_SIZE_4MB;
    ULONG_PTR RegionSize = (flAllocationType & MEM_4MB_PAGES) ? 64 : 1;

    if (VirtualAddress && ((ULONG_PTR)VirtualAddress & (dwPageSize - 1)))
    {
        SetLastError(ERROR_INVALID_PARAMETER);
        return nullptr;
    }

    if (MEMORY_BASIC_INFORMATION mbi;
        !VirtualAddress || !VirtualQuery(VirtualAddress, &mbi, sizeof(mbi)) || mbi.State == MEM_FREE)
    {
        VirtualAddress = EraVirtualAlloc(VirtualAddress, NumberOfPages * PAGE_SIZE_64K, MEM_RESERVE | flAllocationType,
                                         PAGE_NOACCESS);