On Fri, Mar 27, 2015 at 1:31 PM, Linus Torvalds <torva...@linux-foundation.org> wrote: > On Fri, Mar 27, 2015 at 1:16 PM, Andy Lutomirski <l...@amacapital.net> wrote: >> >> Does it matter on 32-bit kernels? There's no swapgs, so IRQs should >> still be safe, and we have a real stack pointer before sysexit. > > Fair enough. On 32-bit, the only worry is the race between "return to > user space" and "something set a thread flag", resulting in delayed > signals and/or higher scheduling latency etc. So on 32-bit, the bug is > much less of an issue, I agree.
Right, except for one nasty case: KVM user return notifiers. It's possible we'd re-enter user mode with some MSRs set wrong. Yuck. --Andy > > So yeah, using sysretl instead of sti+sysexit on 64-bit sounds more > reasonable given the potential worry about sti+sysexit atomicity in > the presense of nmi's. > > Linus -- Andy Lutomirski AMA Capital Management, LLC -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
