On Thu, 12 Jun 2003, David Mosberger wrote:
>
> Is it possible to constrain the FIXADDR range on x86/x86-64
> (FIXADDR_START-FIXADDR_TOP) such that the entire range is read-only by
> user-level? If so, we could simplify the permission test like this:
Well, you could replace the uses of FIXADDR_START/FIXADDR_TOP with
something like FIXADDR_USER_START/FIXADDR_USER_TOP, and then force those
to cover only the _one_ user-accessible page.
Something like
#define FIXADDR_USER_START (fix_to_virt(FIX_VSYSCALL))
#define FIXADDR_USER_END (FIXADDR_USER_START + PAGE_SIZE)
should work. In that case you can drop the page table testing, since we
"know" it is safe.
But I'm too lazy to test, so please send a tested patch,
Linus
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This archive was generated by hypermail 2b29 : Sun Jun 15 2003 - 22:00:35 EST