Pull s390 fixes from Heiko Carstens:
- fix incorrect dereference of the ext_params2 external interrupt
parameter, which leads to an instant kernel crash if a pfault
interrupt occurs.
- add forgotten stack unwinder support, and fix memory leak for the
new machine check handler stack.
- fix inline assembly register clobbering due to KASAN code
instrumentation.
* tag 's390-5.12-6' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
s390/setup: use memblock_free_late() to free old stack
s390/irq: fix reading of ext_params2 field from lowcore
s390/unwind: add machine check handler stack
s390/cpcmd: fix inline assembly register clobbering