On Wed, Jul 10, 2019 at 04:37:41PM -0700, Xing, Cedric wrote: > On 7/10/2019 4:15 PM, Jarkko Sakkinen wrote: > > On Thu, Jul 11, 2019 at 01:46:28AM +0300, Jarkko Sakkinen wrote: > > > On Wed, Jul 10, 2019 at 11:08:37AM -0700, Xing, Cedric wrote: > > > > > With these conclusions I think the current vDSO API is sufficient for > > > > > Linux. > > > > > > > > The new vDSO API is to support data exchange on stack. It has nothing > > > > to do > > > > with debugging. BTW, the community has closed on this. > > > > > > And how that is useful? > > > > > > > The CFI directives are for stack unwinding. They don't affect what the > > > > code > > > > does so you can just treat them as NOPs if you don't understand what > > > > they > > > > do. However, they are useful to not only debuggers but also exception > > > > handling code. libunwind also has a setjmp()/longjmp() implementation > > > > based > > > > on CFI directives. > > > > > > Of course I won't merge code of which usefulness I don't understand. > > > > I re-read the cover letter [1] because it usually is the place > > to "pitch" a feature. > > > > It fails to address two things: > > > > 1. How and in what circumstances is an untrusted stack is a better > > vessel for handling exceptions than the register based approach > > that we already have? > > We are not judging which vessel is better (or the best) among all possible > vessels. We are trying to enable more vessels. Every vessel has its pros and > cons so there's *no* single best vessel.
I think reasonable metric is actually the coverage of the Intel SDK based enclaves. How widely are they in the wild? If the user base is large, it should be reasonable to support this just based on that. /Jarkko
