On Fri, Feb 04, 2022 at 01:08:25AM +0000, Edgecombe, Rick P wrote: > > So how is that going to work? altstack is not an esoteric corner > > case. > > My understanding is that the main usages for the signal stack were > handling stack overflows and corruption. Since the shadow stack only > contains return addresses rather than large stack allocations, and is > not generally writable or pivotable, I thought there was a good > possibility an alt shadow stack would not end up being especially > useful. Does it seem like reasonable guesswork? altstacks are also used in userspace threading implemenations.