On Thu, 2018-01-04 at 06:46 -0800, Dave Hansen wrote: > On 01/04/2018 06:37 AM, David Woodhouse wrote: > > KPTI complicates this a little; the one in entry_SYSCALL_64_trampoline > > can't just jump to the thunk because the thunk isn't mapped. So it gets > > its own copy of the thunk, inline. > > This one call site isn't too painful, of course. > > But, is there anything keeping us from just sticking the thunk in the > entry text section where it would be available while still in the > trampoline?
Not really. Since we have a thunk per register and the trampoline is limited in size, if you wanted to put just the *one* thunk that's needed into the trampoline then it's slightly icky, but all perfectly feasible.
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