New compilers use the floating-point registers as spill registers when
there is high register pressure. In the purgatory however, the afp control
bit is not set. This leads to an exception whenever a floating-point
instruction is used, which again causes an interrupt loop.
Forbid the compiler to use floating-point instructions by adding
-msoft-float to KBUILD_CFLAGS.
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com> Fixes: 840798a1f529 (s390/kexec_file: Add purgatory) Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>