Messages in this thread | | | Subject | Re: [PATCH v7 03/14] x86/cet/ibt: Add IBT legacy code bitmap setup function | From | Dave Hansen <> | Date | Fri, 7 Jun 2019 10:59:37 -0700 |
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On 6/7/19 10:43 AM, Peter Zijlstra wrote: > I've no idea what the kernel should do; since you failed to answer the > question what happens when you point this to garbage. > > Does it then fault or what?
Yeah, I think you'll fault with a rather mysterious CR2 value since you'll go look at the instruction that faulted and not see any references to the CR2 value.
I think this new MSR probably needs to get included in oops output when CET is enabled.
Why don't we require that a VMA be in place for the entire bitmap? Don't we need a "get" prctl function too in case something like a JIT is running and needs to find the location of this bitmap to set bits itself?
Or, do we just go whole-hog and have the kernel manage the bitmap itself. Our interface here could be:
prctl(PR_MARK_CODE_AS_LEGACY, start, size);
and then have the kernel allocate and set the bitmap for those code locations.
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