[Bug go/89123] Too many go test failures on s390x-linux

[rdapp at linux dot ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89123

--- Comment #7 from rdapp at linux dot ibm.com ---
I did a full debug build of libgo and noticed that this changes the behavior of
the executable.  When it would segfault with default -O2 before, it now seems
to rapidly allocate gigabytes of memory.

This happens in

doInit() in cpu_s390x.go:121

where we detect the CPU facilities.

Apparently the stfle call used to be in cpu_s390x.s which does not exist
anymore. Hence, the

{ panic("not implemented for gccgo") }

gets triggers and we end up in

panic.go:133
if len(pp.deferpool) == 0 && sched.deferpool != nil {

pp is 0x0 here and "__go_runtime_error" tries to handle this by a
runtime_panicstring which itself tries to defer again and so on.

Is cpu_s390x.s missing on purpose i.e. should it have been replaced by
something else?