Re: proposal for meltdown-workaround with low overhead

2018-01-05 Thread Alexander Kleinsorge
Hi Tony, at least in the original Paper ( meltdownattack.com/meltdown.pdf ) and in Wikipedia ( en.wikipedia.org/wiki/Meltdown_(security_vulnerability) ) indicate, that the exception variant is the preferred choice (even if it is also possible via branch prediction bending). (I assume, that the

Re: proposal for meltdown-workaround with low overhead

2018-01-04 Thread Alan Cox
On Thu, 4 Jan 2018 15:09:28 -0800 Tony Luck wrote: > On Thu, Jan 4, 2018 at 11:45 AM, Alexander Kleinsorge > wrote: > > As Meltdown-Issue depends on allowing to cause many exceptions (usually : > > accessing an invalid address), we could restrict this misusage easy. > > The accesses to the in

Re: proposal for meltdown-workaround with low overhead

2018-01-04 Thread Tony Luck
On Thu, Jan 4, 2018 at 11:45 AM, Alexander Kleinsorge wrote: > As Meltdown-Issue depends on allowing to cause many exceptions (usually : > accessing an invalid address), we could restrict this misusage easy. The accesses to the invalid address are performed speculatively by the CPU in a code bran