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s390/decompressor: support uncompressed kernel

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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: 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>
This commit is contained in:
Vasily Gorbik 2018-06-13 00:00:25 +02:00 committed by Martin Schwidefsky
parent f16466af38
commit 89b5202e81
5 changed files with 19 additions and 6 deletions
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1
arch/s390/Kconfig
View File

@ -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

4
arch/s390/boot/compressed/Makefile
View File

@ -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)

12
arch/s390/boot/compressed/vmlinux.lds.S
View File

@ -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 = . ;

4
arch/s390/boot/compressed/vmlinux.scr.lds.S
View File

@ -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
}
}

4
arch/s390/boot/head.S
View File

@ -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))