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Date: Sat, 11 Jun 2016 22:48:08 -0600 From: Logan Gunthorpe <logang@...tatee.com> To: "Rafael J. Wysocki" <rjw@...ysocki.net> Cc: Kees Cook <keescook@...omium.org>, "Rafael J. Wysocki" <rafael@...nel.org>, Stephen Smalley <sds@...ho.nsa.gov>, Ingo Molnar <mingo@...nel.org>, Ingo Molnar <mingo@...hat.com>, the arch/x86 maintainers <x86@...nel.org>, "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Andy Lutomirski <luto@...nel.org>, Borislav Petkov <bp@...en8.de>, Denys Vlasenko <dvlasenk@...hat.com>, Brian Gerst <brgerst@...il.com> Subject: Re: PROBLEM: Resume form hibernate broken by setting NX on gap Hey, On 11/06/16 07:05 PM, Rafael J. Wysocki wrote: >> 1) Commit ab76f7b4ab only extends the NX bit between __ex_table and >> rodata; which, by my understanding, shouldn't be used by anything. And >> __ex_table and rodata are fixed by the kernel's binary so both symbols >> should be the same in both the image kernel and the boot kernel given >> that both are running from the same binary. > > Well, what if the kernel is relocated? Ah, I'm sure I don't fully grasp the implications of that but I would assume that if the image kernel were located somewhere else it would still be far away from the boot kernel's ex_table/rodata boundary. >> 2) When ab76f7b4ab is reverted, hibernation seems to work 100%. Though, >> when it's in place, it only works some of the time. Given that commit is >> only extending the NX region a bit, if there is some random mismatch, >> why does it never reach rodata? In other words, why is rodata a magic >> line that seems to work all the time -- why doesn't this random mismatch >> ever extend into the rodata region? rodata isn't _that_ far away from >> the end of ex_table. > > That's a very good question. :-) Yeah, I guess if we knew the answer we'd understand what was going on and have a fix. > Can you please check if the patch below makes any difference? I'm afraid it's no different. The kernel still freezes on resume. Though, no warnings with this one. Thanks, Logan
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