RFR: 8135097: Unmap failure for executable memory on windows

[Jiangli Zhou]

Hi,

Please review the following bug fix for windows os::pd_unmap_memory(). The windows os::pd_map_memory() and os::pd_unmap_memory() have incompatible implementations. The windows os::pd_map_memory() uses VirtualAlloc/VirtualProtect to create executable mapping and CreateFileMapping/MapViewOfFileEx for non-executable memory mapping, while os::pd_unmap_memory() just calls UnmapViewOfFile(). For executable mapping, UnmapViewOfFile() call fails because the memory was not mapped using CreateFileMapping/MapViewOfFileEx. The failure was observed with CDS when it tries to unmap shared executable 'mc’ region on windows-32 platform.

bug: JDK-8135097 <https://bugs.openjdk.java.net/browse/JDK-8135097>
webrev: http://cr.openjdk.java.net/~jiangli/8135097/webrev.00/

Tested with JPRT, unit test.

Thanks,
Jiangli