Re: [PATCH 00/11] (v2) Mitigation against unsafe data speculation (CVE-2017-5753)

[Jeff Law <law@redhat.com>]

On 08/02/2018 02:19 PM, John David Anglin wrote:
> On 2018-08-02 2:40 PM, Jeff Law wrote:
>> It's been eons.   I think there's enough building blocks on the PA to
>> mount a spectre v1 attack.  They've got branch prediction with varying
>> degress of speculative execution, caches and user accessable cycle
>> timers.
> Yes.
>>
>> There's varying degrees of out of order execution all the way back in
>> the PA7xxx processors (hit-under-miss) to full o-o-o execution in the
>> PA8xxx series (including the PA8900 that's in the rp3440).
> However, as far as I know, loads and stores are always ordered.
I'm pretty sure that's not true on PA8000 class machines:

You can get the details here:

http://web.archive.org/web/20040214092531/http://www.cpus.hp.com/technical_references/advperf.shtml

It describes in reasonable detail how the load/store reorder buffer and
the address reorder buffer works as well as the tag checking to detect
when a speculative load was executed and its results had to be thrown
away due to a store-to-load dependency check in the ARB.

But again, given the state of the target, I'm not at all concerned about
mitigating spectre v1.

Jeff