s390/decompressor: trim the kernel image up to 1M

Move head64.S main kernel entry point "startup_continue" to 0x100000 and
trim everything which is below 1M during build. So, that the decompressor
would unpack the main kernel image, move it to 0x100000 and jump to
startup_continue.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/boot/compressed/Makefile

@@ -24,7 +24,7 @@ LDFLAGS_vmlinux := --oformat $(LD_BFD) -e startup -T
 $(obj)/vmlinux: $(obj)/vmlinux.lds $(OBJECTS)
 	$(call if_changed,ld)
 
-TRIM_HEAD_SIZE := 0x11000
+TRIM_HEAD_SIZE := 0x100000
 
 sed-sizes := -e 's/^\([0-9a-fA-F]*\) . \(__bss_start\|_end\)$$/\#define SZ\2 (0x\1 - $(TRIM_HEAD_SIZE))/p'
 

arch/s390/boot/compressed/head.S

@@ -23,7 +23,7 @@ ENTRY(startup_continue)
 	aghi	%r15,-160
 	brasl	%r14,decompress_kernel
 	# Set up registers for memory mover. We move the decompressed image to
-	# 0x11000, where startup_continue of the decompressed image is supposed
+	# 0x100000, where startup_continue of the decompressed image is supposed
 	# to be.
 	lgr	%r4,%r2
 	lg	%r2,.Loffset-.LPG1(%r13)
@@ -33,7 +33,7 @@ ENTRY(startup_continue)
 	la	%r1,0x200
 	mvc	0(mover_end-mover,%r1),mover-.LPG1(%r13)
 	# When the memory mover is done we pass control to
-	# arch/s390/kernel/head64.S:startup_continue which lives at 0x11000 in
+	# arch/s390/kernel/head64.S:startup_continue which lives at 0x100000 in
 	# the decompressed image.
 	lgr	%r6,%r2
 	br	%r1
@@ -47,6 +47,6 @@ mover_end:
 .Lstack:
 	.quad	0x8000 + (1<<(PAGE_SHIFT+THREAD_SIZE_ORDER))
 .Loffset:
-	.quad	0x11000
+	.quad	0x100000
 .Lmvsize:
 	.quad	SZ__bss_start

arch/s390/kernel/head64.S

@@ -16,6 +16,7 @@
 #include <asm/page.h>
 
 __HEAD
+	.org	0x100000 - 0x11000		# head.o ends at 0x11000
 ENTRY(startup_continue)
 	tm	__LC_STFLE_FAC_LIST+5,0x80	# LPP available ?
 	jz	0f
@@ -88,7 +89,6 @@ ENTRY(startup_continue)
 
 ENTRY(_ehead)
 
-	.org	0x100000 - 0x11000	# head.o ends at 0x11000
 #
 # startup-code, running in absolute addressing mode
 #