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| author | Vasily Gorbik <gor@linux.vnet.ibm.com> | 2018-03-05 09:58:00 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2018-03-18 23:02:07 -0700 |
| commit | 81796a3c6a4ad3ba0408c807ec14f50e6270ec23 (patch) | |
| tree | f0906b8ea616d35acf2421c69bb9f25c58b080a5 /arch/s390/boot/compressed/Makefile | |
| parent | c7260ca335a09fb186885c80bd6022318c10c541 (diff) | |
s390/decompressor: trim uncompressed image head during the build
It seems to be suboptimal to compress the entire image, so that we
could decompress and throw away the first 68k (0x11000) during the boot
process. This patch trims 0x11000 bytes during the build process and
adjusts symbols in size.h accordingly.
Besides making bzImage smaller, this change would also be a benefit
for kaslr. It allows to decompress the kernel right to desired offset,
without worrying about dead weight in front of the decompressed image.
Signed-off-by: Vasily Gorbik <gor@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/boot/compressed/Makefile')
| -rw-r--r-- | arch/s390/boot/compressed/Makefile | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/arch/s390/boot/compressed/Makefile b/arch/s390/boot/compressed/Makefile index 26d6a94f40f6..5766f7b9b271 100644 --- a/arch/s390/boot/compressed/Makefile +++ b/arch/s390/boot/compressed/Makefile @@ -29,11 +29,16 @@ LDFLAGS_vmlinux := --oformat $(LD_BFD) -e startup -T $(obj)/vmlinux: $(obj)/vmlinux.lds $(OBJECTS) $(call if_changed,ld) -sed-sizes := -e 's/^\([0-9a-fA-F]*\) . \(__bss_start\|_end\)$$/\#define SZ\2 0x\1/p' +TRIM_HEAD_SIZE := 0x11000 -quiet_cmd_sizes = GEN $@ +sed-sizes := -e 's/^\([0-9a-fA-F]*\) . \(__bss_start\|_end\)$$/\#define SZ\2 (0x\1 - $(TRIM_HEAD_SIZE))/p' + +quiet_cmd_sizes = GEN $@ cmd_sizes = $(NM) $< | sed -n $(sed-sizes) > $@ +quiet_cmd_trim_head = TRIM $@ + cmd_trim_head = tail -c +$$(($(TRIM_HEAD_SIZE) + 1)) $< > $@ + $(obj)/sizes.h: vmlinux $(call if_changed,sizes) @@ -43,10 +48,13 @@ $(obj)/head.o: $(obj)/sizes.h CFLAGS_misc.o += -I$(objtree)/$(obj) $(obj)/misc.o: $(obj)/sizes.h -OBJCOPYFLAGS_vmlinux.bin := -R .comment -S -$(obj)/vmlinux.bin: vmlinux +OBJCOPYFLAGS_vmlinux.bin.full := -R .comment -S +$(obj)/vmlinux.bin.full: vmlinux $(call if_changed,objcopy) +$(obj)/vmlinux.bin: $(obj)/vmlinux.bin.full + $(call if_changed,trim_head) + vmlinux.bin.all-y := $(obj)/vmlinux.bin suffix-$(CONFIG_KERNEL_GZIP) := gz |