s390/sclp: do not use static sccbs

The sccbs for init/read/sdias/early have to be located below 2 GB, and
they are currently defined as a static buffer.

With a relocatable kernel that could reside at any place in memory, this
will no longer guarantee the location below 2 GB, so use a dynamic
GFP_DMA allocation instead.

The sclp_early_sccb buffer needs special handling, as it can be used
very early, and by both the decompressor and also the decompressed
kernel. Therefore, a fixed 4 KB buffer is introduced at 0x11000, the
former PARMAREA_END. The new PARMAREA_END is now 0x12000, and it is
renamed to HEAD_END, as it is rather the end of head.S and not the end
of the parmarea.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S
index d585c4dbdac7..c6b4b4c5dd58 100644
--- a/arch/s390/boot/head.S
+++ b/arch/s390/boot/head.S
@@ -336,4 +336,7 @@ ENTRY(startup_kdump)
         .byte   "root=/dev/ram0 ro"
         .byte   0
 
-        .org    0x11000
+        .org    EARLY_SCCB_OFFSET
+        .fill   4096
+
+        .org    HEAD_END