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Commit 89b5202e authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Martin Schwidefsky
Browse files

s390/decompressor: support uncompressed kernel 



Implement uncompressed kernel support (when "None" is picked in kernel
compression mode list). In that case an actual decompression code is
skipped and control is passed from boot/head.S to startup_continue in
kernel/head64.S. To achieve that uncompressed kernel payload is
conditionally put at 0x100000 in bzImage.

In reality this is very close to classic uncompressed kernel "image",
but the decompressor has its own build and link process,
kernel/head64.S lives at 0x100000 rather than at 0x11000, and .bss
section is reused for both stages.

Reviewed-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent f16466af

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -146,6 +146,7 @@ config S390 
	select HAVE_KERNEL_LZ4

	select HAVE_KERNEL_LZMA

	select HAVE_KERNEL_LZO

	select HAVE_KERNEL_UNCOMPRESSED

	select HAVE_KERNEL_XZ

	select HAVE_KPROBES

	select HAVE_KRETPROBES

arch/s390/boot/compressed/Makefile

+2 −2
Original line number Diff line number Diff line
@@ -9,10 +9,10 @@ KCOV_INSTRUMENT := n 
GCOV_PROFILE := n

UBSAN_SANITIZE := n



obj-y	:= head.o misc.o piggy.o

obj-y	:= $(if $(CONFIG_KERNEL_UNCOMPRESSED),,head.o misc.o) piggy.o

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 += vmlinux.scr.lds sizes.h $(obj-y)

targets += vmlinux.scr.lds $(obj-y) $(if $(CONFIG_KERNEL_UNCOMPRESSED),,sizes.h)



KBUILD_AFLAGS := $(KBUILD_AFLAGS_DECOMPRESSOR)

KBUILD_CFLAGS := $(KBUILD_CFLAGS_DECOMPRESSOR)

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

+8 −4
Original line number Diff line number Diff line
@@ -23,13 +23,10 @@ SECTIONS 
		*(.text.*)

		_etext = . ;

	}

	.rodata.compressed : {

		*(.rodata.compressed)

	}

	.rodata : {

		_rodata = . ;

		*(.rodata)	 /* read-only data */

		*(.rodata.*)

		EXCLUDE_FILE (*piggy.o) *(.rodata.*)

		_erodata = . ;

	}

	.data :	{
@@ -38,6 +35,13 @@ SECTIONS 
		*(.data.*)

		_edata = . ;

	}

	startup_continue = 0x100000;

#ifdef CONFIG_KERNEL_UNCOMPRESSED

	. = 0x100000;

#endif

	.rodata.compressed : {

		*(.rodata.compressed)

	}

	. = ALIGN(256);

	.bss : {

		_bss = . ;

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

+4 −0
Original line number Diff line number Diff line
@@ -2,10 +2,14 @@ 
SECTIONS

{

  .rodata.compressed : {

#ifndef CONFIG_KERNEL_UNCOMPRESSED

	input_len = .;

	LONG(input_data_end - input_data) input_data = .;

#endif

	*(.data)

#ifndef CONFIG_KERNEL_UNCOMPRESSED

	output_len = . - 4;

	input_data_end = .;

#endif

	}

}

arch/s390/boot/head.S

+4 −0
Original line number Diff line number Diff line
@@ -310,7 +310,11 @@ ENTRY(startup_kdump) 
	l	%r15,.Lstack-.LPG0(%r13)

	ahi	%r15,-STACK_FRAME_OVERHEAD

	brasl	%r14,verify_facilities

#ifdef CONFIG_KERNEL_UNCOMPRESSED

	jg	startup_continue

#else

	jg	startup_decompressor

#endif



.Lstack:

	.long	0x8000 + (1<<(PAGE_SHIFT+THREAD_SIZE_ORDER))