Messages in this thread | ![/](/images/icornerl.gif) | | From | "Edgecombe, Rick P" <> | Subject | Re: [PATCH v7 21/41] mm: Add guard pages around a shadow stack. | Date | Wed, 8 Mar 2023 22:48:16 +0000 |
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On Tue, 2023-03-07 at 11:44 +0100, David Hildenbrand wrote: > On 07.03.23 11:32, Borislav Petkov wrote: > > On Tue, Mar 07, 2023 at 01:29:50AM +0000, Edgecombe, Rick P wrote: > > > On Mon, 2023-03-06 at 09:08 +0100, Borislav Petkov wrote: > > > > Just typos: > > > > > > All seem reasonable to me. Thanks. > > > > > > For using the log verbiage for the comment, it is quite big. Does > > > something like this seem reasonable? > > > > Yeah, it does. I wouldn't want to lose that explanation in a commit > > message. > > > > However, this special aspect pertains to the shstk implementation > > in x86 > > but the code is generic mm and such arch-specific comments are > > kinda > > unfitting there. > > > > I wonder if it would be better if you could stick that explanation > > somewhere in arch/x86/ and only refer to it in a short comment > > above > > VM_SHADOW_STACK check in stack_guard_start_gap()... > > +1
I can't find a good place for it in the arch code. Basically there is no arch/x86 functionality that has to do with guard pages. The closest is pte_mkwrite() because it at least references VM_SHADOW_STACK but it doesn't really fit.
We could to add an arch version of stack_guard_start_gap() but we had that and removed it for other style reasons. Code duplication IIRC.
So I thought to just move it elsewhere in mm.h where VM_SHADOW_STACK is defined.
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