[S390] fix boot failures with compressed kernels

Fix two bugs with the kernel image compression:
1) reset the bss section of the compressed vmlinux
2) clear the high half of the registers for 64 bit early enough
   for the decompression step

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/s390/kernel/head.S b/arch/s390/kernel/head.S
index ca4a62bd862f..9d1f76702d47 100644
--- a/arch/s390/kernel/head.S
+++ b/arch/s390/kernel/head.S
@@ -517,7 +517,10 @@ startup:
         lhi     %r1,2                   # mode 2 = esame (dump)
         sigp    %r1,%r0,0x12            # switch to esame mode
         sam64                           # switch to 64 bit mode
+        larl    %r13,4f
+        lmh     %r0,%r15,0(%r13)        # clear high-order half
         jg      startup_continue
+4:      .fill   16,4,0x0
 #else
         mvi     __LC_AR_MODE_ID,0       # set ESA flag (mode 0)
         l       %r13,4f-.LPG0(%r13)