[BISECTED] kexec regression on PowerBook G4

[Aaro Koskinen]

Hi,

I was trying to upgrade from v5.0 -> v5.1 on PowerBook G4, but when trying
to kexec a kernel the system gets stuck (no errors seen on the console).

Bisected to: 93c4a162b014 ("powerpc/6xx: Store PGDIR physical address
in a SPRG"). This commit doesn't revert cleanly anymore but I tested
that the one before works OK.

With current Linus HEAD (9c7db5004280), it gets a bit further but still
doesn't work: now I get an error on the console after kexec "Starting
new kernel! ... Bye!":

	kernel tried to execute exec-protected page (...) - exploit attempt?

A.