On Fri, Feb 09, 2024 at 08:18:11PM +0000, Edgecombe, Rick P wrote: > On Sat, 2024-02-03 at 00:05 +0000, Mark Brown wrote: > > + if (write_user_shstk_64((u64 __user *)addr, 0)) > > + return false; > > + > > + return true; > > +} > So, don't we want to consume the token on the *new* task's MM, which > was already duplicated but still unmapped? In which case I think the > other arch's would need to GUP regardless of the existence of shadow > stack atomic ops. Yes, that would be better - if nothing else it allows reuse of the same shadow stack for multiple !CLONE_VM clone3()s. > I wonder about adding a shstk_post_fork() to make it easier to think > about and maintain, even if there are no issues today. I agree.
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