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Re: PROBLEM: Resume form hibernate broken by setting NX on gap

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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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Re: PROBLEM: Resume form hibernate broken by setting NX on gap Kees Cook <keescook@chromium.org> - 2016-06-10 20:10 +0200
  Re: PROBLEM: Resume form hibernate broken by setting NX on gap Kees Cook <keescook@chromium.org> - 2016-06-10 20:20 +0200
  Re: PROBLEM: Resume form hibernate broken by setting NX on gap Logan Gunthorpe <logang@deltatee.com> - 2016-06-10 20:20 +0200
  Re: PROBLEM: Resume form hibernate broken by setting NX on gap "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-10 23:30 +0200
    Re: PROBLEM: Resume form hibernate broken by setting NX on gap "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-11 00:30 +0200
      Re: PROBLEM: Resume form hibernate broken by setting NX on gap "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-11 00:30 +0200
        Re: PROBLEM: Resume form hibernate broken by setting NX on gap "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-11 02:10 +0200
          Re: PROBLEM: Resume form hibernate broken by setting NX on gap "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-11 03:50 +0200
            Re: PROBLEM: Resume form hibernate broken by setting NX on gap "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-11 13:50 +0200
              Re: PROBLEM: Resume form hibernate broken by setting NX on gap Logan Gunthorpe <logang@deltatee.com> - 2016-06-11 18:40 +0200
            Re: PROBLEM: Resume form hibernate broken by setting NX on gap Logan Gunthorpe <logang@deltatee.com> - 2016-06-11 19:50 +0200
              Re: PROBLEM: Resume form hibernate broken by setting NX on gap "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-12 03:10 +0200
                Re: PROBLEM: Resume form hibernate broken by setting NX on gap Logan Gunthorpe <logang@deltatee.com> - 2016-06-12 06:50 +0200
                Re: PROBLEM: Resume form hibernate broken by setting NX on gap "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-12 16:30 +0200
                Re: PROBLEM: Resume form hibernate broken by setting NX on gap Logan Gunthorpe <logang@deltatee.com> - 2016-06-12 18:20 +0200
                Re: PROBLEM: Resume form hibernate broken by setting NX on gap "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-06-13 15:40 +0200
      Re: PROBLEM: Resume form hibernate broken by setting NX on gap Logan Gunthorpe <logang@deltatee.com> - 2016-06-11 00:30 +0200

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