Commit 369f91c3 authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Martin Schwidefsky
Browse files

s390/decompressor: rework uncompressed image info collection 



The kernel decompressor has to know several bits of information about
uncompressed image. Currently this info is collected by running "nm" on
uncompressed vmlinux + "sed" and producing sizes.h file. This method
worked well, but it has several disadvantages. Obscure symbols name
pattern matching is fragile. Adding new values makes pattern even
longer. Logic is spread across code and make file. Limited ability to
adjust symbols values (currently magic lma value of 0x100000 is always
subtracted). Apart from that same pieces of information (and more)
would be needed for early memory detection and features like KASLR
outside of boot/compressed/ folder where sizes.h is generated.

To overcome limitations new "struct vmlinux_info" has been introduced
to include values needed for the decompressor and the rest of the
boot code. The only static instance of vmlinux_info is produced during
vmlinux link step by filling in struct fields by the linker (like it is
done with input_data in boot/compressed/vmlinux.scr.lds.S). This way
individual values could be adjusted with all the knowledge linker has
and arithmetic it supports. Later .vmlinux.info section (which contains
struct vmlinux_info) is transplanted into the decompressor image and
dropped from uncompressed image altogether.

While doing that replace "compressed/vmlinux.scr.lds.S" linker
script (whose purpose is to rename .data section in piggy.o to
.rodata.compressed) with plain objcopy command. And simplify
decompressor's linker script.

Reviewed-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: default avatarVasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 8f75582a

arch/s390/boot/compressed/Makefile

+15 −18
Original line number Diff line number Diff line
@@ -9,13 +9,14 @@ KCOV_INSTRUMENT := n 
GCOV_PROFILE := n

UBSAN_SANITIZE := n



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

obj-y	:= $(if $(CONFIG_KERNEL_UNCOMPRESSED),,misc.o) piggy.o info.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 $(obj-y) $(if $(CONFIG_KERNEL_UNCOMPRESSED),,sizes.h)

targets += info.bin $(obj-y)



KBUILD_AFLAGS := $(KBUILD_AFLAGS_DECOMPRESSOR)

KBUILD_CFLAGS := $(KBUILD_CFLAGS_DECOMPRESSOR)

OBJCOPYFLAGS :=



OBJECTS := $(addprefix $(obj)/,$(obj-y))
@@ -23,20 +24,16 @@ LDFLAGS_vmlinux := --oformat $(LD_BFD) -e startup -T 
$(obj)/vmlinux: $(obj)/vmlinux.lds $(objtree)/arch/s390/boot/startup.a $(OBJECTS)

	$(call if_changed,ld)



# extract required uncompressed vmlinux symbols and adjust them to reflect offsets inside vmlinux.bin

sed-sizes := -e 's/^\([0-9a-fA-F]*\) . \(__bss_start\|_end\)$$/\#define SZ\2 (0x\1 - 0x100000)/p'



quiet_cmd_sizes = GEN     $@

      cmd_sizes = $(NM) $< | sed -n $(sed-sizes) > $@



$(obj)/sizes.h: vmlinux

	$(call if_changed,sizes)

OBJCOPYFLAGS_info.bin := -O binary --only-section=.vmlinux.info

$(obj)/info.bin: vmlinux FORCE

	$(call if_changed,objcopy)



CFLAGS_misc.o += -I$(objtree)/$(obj)

$(obj)/misc.o: $(obj)/sizes.h

OBJCOPYFLAGS_info.o := -I binary -O elf64-s390 -B s390:64-bit --rename-section .data=.vmlinux.info

$(obj)/info.o: $(obj)/info.bin FORCE

	$(call if_changed,objcopy)



OBJCOPYFLAGS_vmlinux.bin :=  -R .comment -S

$(obj)/vmlinux.bin: vmlinux

OBJCOPYFLAGS_vmlinux.bin := -O binary --remove-section=.comment --remove-section=.vmlinux.info -S

$(obj)/vmlinux.bin: vmlinux FORCE

	$(call if_changed,objcopy)



vmlinux.bin.all-y := $(obj)/vmlinux.bin
@@ -61,10 +58,10 @@ $(obj)/vmlinux.bin.lzo: $(vmlinux.bin.all-y) 
$(obj)/vmlinux.bin.xz: $(vmlinux.bin.all-y)

	$(call if_changed,xzkern)



LDFLAGS_piggy.o := -r --format binary --oformat $(LD_BFD) -T

$(obj)/piggy.o: $(obj)/vmlinux.scr.lds $(obj)/vmlinux.bin$(suffix-y)

	$(call if_changed,ld)

OBJCOPYFLAGS_piggy.o := -I binary -O elf64-s390 -B s390:64-bit --rename-section .data=.vmlinux.bin.compressed

$(obj)/piggy.o: $(obj)/vmlinux.bin$(suffix-y) FORCE

	$(call if_changed,objcopy)



chkbss := $(filter-out $(obj)/misc.o $(obj)/piggy.o,$(OBJECTS))

chkbss := $(filter-out $(obj)/misc.o $(obj)/piggy.o $(obj)/info.o,$(OBJECTS))

chkbss-target := $(obj)/vmlinux.bin

include $(srctree)/arch/s390/scripts/Makefile.chkbss

arch/s390/boot/compressed/decompressor.h

+11 −2
Original line number Diff line number Diff line
@@ -3,9 +3,18 @@ 
#define BOOT_COMPRESSED_DECOMPRESSOR_H



#ifdef CONFIG_KERNEL_UNCOMPRESSED

static inline void *decompress_kernel(unsigned long *uncompressed_size) {}

static inline void *decompress_kernel(void) {}

#else

void *decompress_kernel(unsigned long *uncompressed_size);

void *decompress_kernel(void);

#endif



struct vmlinux_info {

	unsigned long default_lma;

	void (*entry)(void);

	unsigned long image_size;	/* does not include .bss */

};



extern char _vmlinux_info[];

#define vmlinux (*(struct vmlinux_info *)_vmlinux_info)



#endif /* BOOT_COMPRESSED_DECOMPRESSOR_H */

arch/s390/boot/compressed/misc.c

+6 −9
Original line number Diff line number Diff line
@@ -11,7 +11,6 @@ 
#include <asm/page.h>

#include <asm/sclp.h>

#include <asm/ipl.h>

#include "sizes.h"

#include "decompressor.h"



/*
@@ -26,10 +25,10 @@ 
#define memzero(s, n) memset((s), 0, (n))



/* Symbols defined by linker scripts */

extern char input_data[];

extern int input_len;

extern char _end[];

extern char _bss[], _ebss[];

extern unsigned char _compressed_start[];

extern unsigned char _compressed_end[];



static void error(char *m);
@@ -83,12 +82,12 @@ static void error(char *x) 
	asm volatile("lpsw %0" : : "Q" (psw));

}



void *decompress_kernel(unsigned long *uncompressed_size)

void *decompress_kernel(void)

{

	void *output, *kernel_end;



	output = (void *) ALIGN((unsigned long) _end + HEAP_SIZE, PAGE_SIZE);

	kernel_end = output + SZ__bss_start;

	kernel_end = output + vmlinux.image_size;



#ifdef CONFIG_BLK_DEV_INITRD

	/*
@@ -111,9 +110,7 @@ void *decompress_kernel(unsigned long *uncompressed_size) 
	free_mem_ptr = (unsigned long) _end;

	free_mem_end_ptr = free_mem_ptr + HEAP_SIZE;



	__decompress(input_data, input_len, NULL, NULL, output, 0, NULL, error);

	if (uncompressed_size)

		*uncompressed_size = SZ__bss_start;

	__decompress(_compressed_start, _compressed_end - _compressed_start,

		     NULL, NULL, output, 0, NULL, error);

	return output;

}

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

+15 −6
Original line number Diff line number Diff line
@@ -8,9 +8,6 @@ ENTRY(startup) 


SECTIONS

{

	/* Be careful parts of head_64.S assume startup_32 is at

	 * address 0.

	 */

	. = 0;

	.head.text : {

		_head = . ;
@@ -26,7 +23,7 @@ SECTIONS 
	.rodata : {

		_rodata = . ;

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

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

		*(.rodata.*)

		_erodata = . ;

	}

	.data :	{
@@ -35,14 +32,26 @@ SECTIONS 
		*(.data.*)

		_edata = . ;

	}

	startup_continue = 0x100000;

	/*

	 * uncompressed image info used by the decompressor it should match

	 * struct vmlinux_info. It comes from .vmlinux.info section of

	 * uncompressed vmlinux in a form of info.o

	 */

	. = ALIGN(8);

	.vmlinux.info : {

		_vmlinux_info = .;

		*(.vmlinux.info)

	}



#ifdef CONFIG_KERNEL_UNCOMPRESSED

	. = 0x100000;

#else

	. = ALIGN(8);

#endif

	.rodata.compressed : {

		*(.rodata.compressed)

		_compressed_start = .;

		*(.vmlinux.bin.compressed)

		_compressed_end = .;

	}

	. = ALIGN(256);

	.bss : {

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

deleted100644 → 0
+0 −15
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

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

	}

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE