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
