On Mon, Mar 9, 2020 at 3:19 PM Dave Hansen <dave.hansen@xxxxxxxxx> wrote: > > On 3/9/20 2:12 PM, H.J. Lu wrote: > >> But what are the rules for clone()? Should there be rules for > >> mismatches for CET enabling between threads if a process (not child > >> processes)? > > What did you mean? A threaded application is either CET enabled or not > > CET enabled. A new thread from clone makes no difference. > > Stacks are fundamentally thread-local resources. The registers that > point to them and MSRs that manage shadow stacks are all CPU-thread > local. Nothing is fundamentally tied to the address space shared across > the process. > > A thread might also share *no* control flow with its child. It might > ask the thread to start in code that the parent can never even reach. > > It sounds like you've picked a Linux implementation that has > restrictions on top of the fundamentals. That's not wrong per se, but > it does deserve explanation and deliberate, not experimental design. > > Could you go back to the folks at Intel and try to figure out what this > was designed to *do*? Yes, I'm probably one of those folks. You know > where to find me. :) A threaded application is loaded from disk. The object file on disk is either CET enabled or not CET enabled. -- H.J.
