On Tue, 2024-10-01 at 18:33 +0100, Mark Brown wrote: > > > A shadow stack size is more symmetric on the surface, but I'm not sure it > > > will > > > be easier for userspace to handle. So I think we should just have a > > > pointer to > > > the token. But it will be a usable implementation either way. > > My suspicion would be that if we're doing the pivot to a previously used > shadow stack we'd also be pivoting the regular stack along with it which > would face similar issues with having an unusual method for specifying > the stack top so I don't know how much we're really winning.
I'm not so sure. The thing is a regular stack can be re-used in full - just set the RSP to the end and take advantage of the whole stack. A shadow stack can only be used where there is a token. > Like we > both keep saying either of the interfaces works though, it's just a > taste question with both having downsides. Fair enough.
