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SubjectRe: [PATCH] pstore: use ktime_get_real_fast_ns() instead of __getnstimeofday()
On Thu, Nov 9, 2017 at 4:46 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> On Fri, 10 Nov 2017, Arnd Bergmann wrote:
>> On Fri, Nov 10, 2017 at 12:00 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
>> > Hmm, no. None of the regular accessor functions can be called from NMI
>> > context safely.
>>
>> Right, that's what I mean: it must not get called from NMI context, but it
>> currently is, at least for this case:
>>
>> NMI handler:
>> something bad
>> panic()
>> kmsg_dump()
>> pstore_dump()
>> pstore_record_init()
>> __getnstimeofday()
>>
>> I should probably add that to the changelog text ;-)
>
> Indeed.

Er, so, is this safe to call there? I've had to fix this a few times
now, so if using ktime_get_real_fast_ns() can be used here (and
doesn't return 0) then this is easily an improvement over the existing
"maybe read 0" case pstore has now.

-Kees


--
Kees Cook
Pixel Security

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