RFC: Should x86-64 support arbitrary calling conventions?

[Alexander Monakov]

On Fri, 24 Mar 2017, Florian Weimer wrote:
> > There are also "foreign calls" in ld.so, where functions in libc.so are
> > used and vector registers may be cloberred.
> 
> Right.  But the _dl_fixup path relevant to the trampoline should not
> do that much work.  (Not sure if audit modules come into play here.)
> 
> The largest problem probably is this: IFUNC resolvers would have to be
> compiled in that special way, too, and those can reside in
> applications.

The libc can save vector register as-needed, just before calling external code
(such as ifunc resolvers and audit callbacks).

Alexander