s390: remove 31 bit support

Remove the 31 bit support in order to reduce maintenance cost and
effectively remove dead code. Since a couple of years there is no
distribution left that comes with a 31 bit kernel.

The 31 bit kernel also has been broken since more than a year before
anybody noticed. In addition I added a removal warning to the kernel
shown at ipl for 5 minutes: a960062e58 ("s390: add 31 bit warning
message") which let everybody know about the plan to remove 31 bit
code. We didn't get any response.

Given that the last 31 bit only machine was introduced in 1999 let's
remove the code.
Anybody with 31 bit user space code can still use the compat mode.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/boot/compressed/Makefile

@@ -4,13 +4,11 @@
 # create a compressed vmlinux image from the original vmlinux
 #
 
-BITS := $(if $(CONFIG_64BIT),64,31)
-
 targets	:= vmlinux.lds vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2
 targets += vmlinux.bin.xz vmlinux.bin.lzma vmlinux.bin.lzo vmlinux.bin.lz4
-targets += misc.o piggy.o sizes.h head$(BITS).o
+targets += misc.o piggy.o sizes.h head64.o
 
-KBUILD_CFLAGS := -m$(BITS) -D__KERNEL__ $(LINUX_INCLUDE) -O2
+KBUILD_CFLAGS := -m64 -D__KERNEL__ $(LINUX_INCLUDE) -O2
 KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
 KBUILD_CFLAGS += $(cflags-y) -fno-delete-null-pointer-checks
 KBUILD_CFLAGS += $(call cc-option,-mpacked-stack)
@@ -19,7 +17,7 @@ KBUILD_CFLAGS += $(call cc-option,-ffreestanding)
 GCOV_PROFILE := n
 
 OBJECTS := $(addprefix $(objtree)/arch/s390/kernel/, head.o sclp.o ebcdic.o)
-OBJECTS += $(obj)/head$(BITS).o $(obj)/misc.o $(obj)/piggy.o
+OBJECTS += $(obj)/head64.o $(obj)/misc.o $(obj)/piggy.o
 
 LDFLAGS_vmlinux := --oformat $(LD_BFD) -e startup -T
 $(obj)/vmlinux: $(obj)/vmlinux.lds $(OBJECTS)
@@ -34,8 +32,8 @@ quiet_cmd_sizes = GEN $@
 $(obj)/sizes.h: vmlinux
 	$(call if_changed,sizes)
 
-AFLAGS_head$(BITS).o += -I$(obj)
-$(obj)/head$(BITS).o: $(obj)/sizes.h
+AFLAGS_head64.o += -I$(obj)
+$(obj)/head64.o: $(obj)/sizes.h
 
 CFLAGS_misc.o += -I$(obj)
 $(obj)/misc.o: $(obj)/sizes.h

arch/s390/boot/compressed/head31.S

@@ -1,51 +0,0 @@
-/*
- * Startup glue code to uncompress the kernel
- *
- * Copyright IBM Corp. 2010
- *
- *   Author(s):	Martin Schwidefsky <schwidefsky@de.ibm.com>
- */
-
-#include <linux/init.h>
-#include <linux/linkage.h>
-#include <asm/asm-offsets.h>
-#include <asm/thread_info.h>
-#include <asm/page.h>
-#include "sizes.h"
-
-__HEAD
-ENTRY(startup_continue)
-	basr	%r13,0			# get base
-.LPG1:
-	# setup stack
-	l	%r15,.Lstack-.LPG1(%r13)
-	ahi	%r15,-96
-	l	%r1,.Ldecompress-.LPG1(%r13)
-	basr	%r14,%r1
-	# setup registers for memory mover & branch to target
-	lr	%r4,%r2
-	l	%r2,.Loffset-.LPG1(%r13)
-	la	%r4,0(%r2,%r4)
-	l	%r3,.Lmvsize-.LPG1(%r13)
-	lr	%r5,%r3
-	# move the memory mover someplace safe
-	la	%r1,0x200
-	mvc	0(mover_end-mover,%r1),mover-.LPG1(%r13)
-	# decompress image is started at 0x11000
-	lr	%r6,%r2
-	br	%r1
-mover:
-	mvcle	%r2,%r4,0
-	jo	mover
-	br	%r6
-mover_end:
-
-	.align	8
-.Lstack:
-	.long	0x8000 + (1<<(PAGE_SHIFT+THREAD_ORDER))
-.Ldecompress:
-	.long	decompress_kernel
-.Loffset:
-	.long	0x11000
-.Lmvsize:
-	.long	SZ__bss_start

arch/s390/boot/compressed/vmlinux.lds.S

@@ -1,12 +1,7 @@
 #include <asm-generic/vmlinux.lds.h>
 
-#ifdef CONFIG_64BIT
 OUTPUT_FORMAT("elf64-s390", "elf64-s390", "elf64-s390")
 OUTPUT_ARCH(s390:64-bit)
-#else
-OUTPUT_FORMAT("elf32-s390", "elf32-s390", "elf32-s390")
-OUTPUT_ARCH(s390:31-bit)
-#endif
 
 ENTRY(startup)