Messages in this thread | | | Date | Tue, 9 Nov 1999 11:35:44 -0700 (MST) | From | Mark Jackson <> | Subject | Page directory entries for kernel page tables marked User - bug? |
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Hello,
I've been looking at kernel page directory/page tables on iX86 platforms. I noticed that when the PSE flag is 1 (page size extensions) the kernel is mapped using 4Meg pages and they are marked with the User/Supervisor flag set to Supervisor. This seems to be correct, since the kernel pages are protected.
However, when the PSE flag is 0 on processors that can't handle the large page extensions, the directory entries which point to page tables that correspond to kernel memory are marked as User. This would seem to be incorrect, since a task can then change the page table mappings from any priveledge level.
I don't know why this would be, and I'm not knowledgable in the kernel code enough to know where to look to fix it. But it seems to be a bug unless there is a reason for this (which I can't think of)
Please CC: me on any responses since I don't subscribe to the kernel mailing list.
Thanks,
Mark Jackson
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