Messages in this thread | | | Subject | Re: [PATCH] x86/mm: Unbreak modules that rely on external PAGE_KERNEL availability | From | Tom Lendacky <> | Date | Wed, 8 Nov 2017 15:36:31 -0600 |
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On 11/8/2017 3:23 PM, Linus Torvalds wrote: > On Wed, Nov 8, 2017 at 1:15 PM, Borislav Petkov <bp@suse.de> wrote: >> >> Right, AFAIRC, the main reason for this being an export was because if >> we hid it in a function, you'd have all those function calls as part of >> the _PAGE_* macros and that's just crap. > > Yes, that would be worse. > > I was thinking that maybe we could have a fixed "encrypt" bit in our > PTE, and then replace that "software bit" with whatever the real > hardware mask is (if any). > > Because it's nasty to have these constants that _used_ to be > constants, and still _look_ like constants, suddely do stupid memory > reads from random kernel data. > > So _this_ is the underflying problem: > > #define _PAGE_ENC (_AT(pteval_t, sme_me_mask)) > > because that is simply not how the _PAGE_xyz macros should work! > > So it should have been a fixed bit to begin with, and the dynamic part > should have been elsewhere. > > The whole EXPORT_SYMBOL() thing is just a symptom of that fundamental > error. Modules - GPL or not - should _never_ have to know or care > about this _PAGE_ENC bit madness, simply because it shouldn't have > been there.
I'll look into that and see what I can come up with.
Thanks, Tom
> > Linus >
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