On Thu, Jul 23, 2015 at 1:52 PM, Willy Tarreau <w...@1wt.eu> wrote: > On Thu, Jul 23, 2015 at 01:38:33PM -0700, Linus Torvalds wrote: >> On Thu, Jul 23, 2015 at 1:21 PM, Andy Lutomirski <l...@amacapital.net> wrote: >> > >> > 2. Forbid IRET inside NMIs. Doable but maybe not that pretty. >> > >> > We haven't considered: >> > >> > 3. Forbid faults (other than MCE) inside NMI. >> >> I'd really prefer #2. #3 depends on us getting many things right, and >> never introducing new cases in the future. >> >> #2, in contrast, seems to be fairly localized. Yes, RF is an issue, >> but returning to user space with RF clear doesn't really seem to be >> all that problematic. > > What's the worst case that can happen with RF cleared when returing > to user space ? My understanding is that it's just that we risk to > break again on an instruction that had a break point set and which > already triggered the breakpoint, right ?
I assume Linus meant returning to kernel space with RF clear. Returns to userspace have their own fancy logic here, and it's survived for a couple of releases, including through an explicit test of RF handling :) --Andy -- 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/
