On Thu, Jun 29, 2017 at 01:54:13PM -0400, Rik van Riel wrote: > On Thu, 2017-06-29 at 10:47 -0700, Kees Cook wrote: > > On Thu, Jun 29, 2017 at 10:05 AM, Christoph Lameter <c...@linux.com> > > wrote: > > > On Sun, 25 Jun 2017, Kees Cook wrote: > > > > > > > The difference gets lost in the noise, but if the above is > > > > sensible, > > > > it's 0.07% slower. ;) > > > > > > Hmmm... These differences add up. Also in a repetative benchmark > > > like that > > > you do not see the impact that the additional cacheline use in the > > > cpu > > > cache has on larger workloads. Those may be pushed over the edge of > > > l1 or > > > l2 capacity at some point which then causes drastic regressions. > > > > Even if that is true, it may be worth it to some people to have the > > protection. Given that is significantly hampers a large class of heap > > overflow attacks[1], I think it's an important change to have. I'm > > not > > suggesting this be on by default, it's cleanly behind > > CONFIG-controlled macros, and is very limited in scope. If you can > > Ack > > it we can let system builders decide if they want to risk a possible > > performance hit. I'm pretty sure most distros would like to have this > > protection. > > I could certainly see it being useful for all kinds of portable > and network-connected systems where security is simply much > more important than performance.
Indeed, I believe we would enable this in our kernels. Cheers, Tycho
