Commit "s390: fix handling of runtime instrumentation psw bit" (5ebf250dab)
changed the behavior of setting the runtime instrumentation psw bit. This
commit restores the original logic:
1. When returning from the signal handler, the runtime instrumentation psw bit
is restored to its saved state.
2. If the runtime instrumentation psw bit is enabled during the signal handler,
it is always turned off when leaving the signal handler. The saved state
is restored as described in 1. That also implies that turning on runtime
instrumentation in the signal handler is only effective while running in the
signal context.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
aa7e04b380