Re: ktime_get_ts64() splat during resume

[chenyu <yu.chen.surf@gmail.com>]

On Fri, Jun 17, 2016 at 11:28 PM, Rafael J. Wysocki <rafael@kernel.org> wrote:
> On Fri, Jun 17, 2016 at 4:33 PM, Borislav Petkov <bp@alien8.de> wrote:
>> Ok,
>>
>> bisect is done, full log below.
>>
>> Rafael, that fix
>>
>>   70595b479ce1 ("x86/power/64: Fix crash whan the hibernation code passes control to the image kernel")
>>
>> breaks s2disk here. It explodes during resume and a statically allocated
>> struct's member is NULL. See
>>
>> https://lkml.kernel.org/r/20160617105435.GB15997@pd.tnic
>>
>> for the splat and some debugging attempts.
>>
>> Reverting 70595b479ce1 fixes the issue here.
>
> Quite evidently, memory is corrupted in the image kernel, but this
> particular commit only affects the boot kernel, so it can't really
> corrupt anything in the image one.
>
In previous patch,
before we jump to the new kernel entry, we add the
text mapping to temp_level4_pgt,

         /* switch over to the temporary kernel text mapping */
        movq    %r8, (%r9)
If I understand correctly,  r9 contains the virtual address
of restore_pgd_addr, since the page table for restore_pgd_addr might be
incoherent across hibernation(as NX patch changes the kernel text mapping
to dynamically mapping), so we might write pmd entry to an incorrect place in
temp_level4_pgt?

Yu