Messages in this thread | | | Date | Mon, 03 Mar 2008 14:55:30 -0800 | From | "H. Peter Anvin" <> | Subject | Re: bisected boot regression post 2.6.25-rc3.. please revert |
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Segher Boessenkool wrote: >>> so (on 32-bit) ~_PAGE_PSE is ~0x80L is 0xffffff7f, which when cast to >>> 64-bit is 0x00000000ffffff7f, >> >> Actually, it is signed, so this isn't true. Comments about unsafeness >> still apply. > > It turns out that PAGE_SIZE is unsigned. So this gives us for > > (~PAGE_MASK & ~_PAGE_USER & ~_PAGE_PSE & ~_PAGE_NX) > > the types UL, L, L, ULL resp. > > The associativity of & is left-to-right, so this in turn becomes > > UL, L, ULL > > UL, ULL > > ULL > > and that cast from UL to ULL doesn't sign-extend. >
All the masks either need to be the proper size or signed.
-hpa
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