On Thu, Oct 27, 2016 at 10:46:38AM +0200, Pavel Machek wrote: > And actually, printk() is not needed, udelay(50msec) is. Reason is, > that DRAM becomes unreliable if about milion cache misses happen in > under 64msec -- so I'd like to slow the system down in such cases to > prevent bug from biting me. > > (Details are here > https://googleprojectzero.blogspot.cz/2015/03/exploiting-dram-rowhammer-bug-to-gain.html > ). Bug is exploitable to get local root; it is also exploitable to > gain local code execution from javascript... so it is rather severe.
Cute, a rowhammer defence. So we can do in-kernel perf events too, see for example kernel/watchdog.c:wd_hw_attr and its users. I suppose you want PERF_COUNT_HW_CACHE_MISSES as config, although depending on platform you could use better (u-arch specific) events.
