On Tue, Apr 22, 2014 at 2:51 PM, H. Peter Anvin <h...@zytor.com> wrote: > On 04/22/2014 11:17 AM, Brian Gerst wrote: >>> >>> That is the entry condition that we have to deal with. The fact that >>> the switch to the IST is unconditional is what makes ISTs hard to deal with. >> >> Right, that is why you switch away from the IST as soon as possible, >> copying the data that is already pushed there to another stack so it >> won't be overwritten by a recursive fault. >> > > That simply will not work if you can take a #GP due to the "safe" MSR > functions from NMI and #MC context, which would be my main concern.
In that case (#2 above), you would switch to the previous %rsp (in the NMI/MC stack), copy the exception frame from the IST, and continue with the #GP handler. That effectively is the same as it is today, where no stack switch occurs on the #GP fault. -- 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/
