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Commit 15426ca4 authored by Vasily Gorbik's avatar Vasily Gorbik Committed by Martin Schwidefsky
Browse files

s390: rescue initrd as early as possible 



To avoid multi-stage initrd rescue operation and to simplify
assumptions during early memory allocations move initrd at some final
safe destination as early as possible. This would also allow us to
drop .bss usage restrictions for some files.

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 3b076dca

arch/s390/boot/compressed/decompressor.h

+2 −0
Original line number Diff line number Diff line
@@ -7,11 +7,13 @@ static inline void *decompress_kernel(void) {} 
#else

void *decompress_kernel(void);

#endif

unsigned long mem_safe_offset(void);



struct vmlinux_info {

	unsigned long default_lma;

	void (*entry)(void);

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

	unsigned long bss_size;		/* uncompressed image .bss size */

};



extern char _vmlinux_info[];

arch/s390/boot/compressed/misc.c

+13 −16
Original line number Diff line number Diff line
@@ -83,25 +83,22 @@ static void error(char *x) 
	asm volatile("lpsw %0" : : "Q" (psw));

}



void *decompress_kernel(void)

{

	void *output, *kernel_end;

#define decompress_offset ALIGN((unsigned long)_end + HEAP_SIZE, PAGE_SIZE)



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

	kernel_end = output + vmlinux.image_size;



#ifdef CONFIG_BLK_DEV_INITRD

unsigned long mem_safe_offset(void)

{

	/*

	 * Move the initrd right behind the end of the decompressed

	 * kernel image. This also prevents initrd corruption caused by

	 * bss clearing since kernel_end will always be located behind the

	 * current bss section..

	 * due to 4MB HEAD_SIZE for bzip2

	 * 'decompress_offset + vmlinux.image_size' could be larger than

	 * kernel at final position + its .bss, so take the larger of two

	 */

	if (INITRD_START && INITRD_SIZE && kernel_end > (void *) INITRD_START) {

		memmove(kernel_end, (void *) INITRD_START, INITRD_SIZE);

		INITRD_START = (unsigned long) kernel_end;

	return max(decompress_offset + vmlinux.image_size,

		   vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size);

}

#endif



void *decompress_kernel(void)

{

	void *output = (void *)decompress_offset;



	__decompress(_compressed_start, _compressed_end - _compressed_start,

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

arch/s390/boot/startup.c

+24 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

#include <linux/string.h>

#include <asm/setup.h>

#include "compressed/decompressor.h"

#include "boot.h"



#ifdef CONFIG_KERNEL_UNCOMPRESSED

unsigned long mem_safe_offset(void)

{

	return vmlinux.default_lma + vmlinux.image_size + vmlinux.bss_size;

}

#endif



static void rescue_initrd(void)

{

	unsigned long min_initrd_addr;



	if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))

		return;

	if (!INITRD_START || !INITRD_SIZE)

		return;

	min_initrd_addr = mem_safe_offset();

	if (min_initrd_addr <= INITRD_START)

		return;

	memmove((void *)min_initrd_addr, (void *)INITRD_START, INITRD_SIZE);

	INITRD_START = min_initrd_addr;

}



void startup_kernel(void)

{

	void *img;



	rescue_initrd();

	if (!IS_ENABLED(CONFIG_KERNEL_UNCOMPRESSED)) {

		img = decompress_kernel();

		memmove((void *)vmlinux.default_lma, img, vmlinux.image_size);

arch/s390/kernel/early_nobss.c

+0 −22
Original line number Diff line number Diff line
@@ -13,7 +13,6 @@ 
#include <linux/string.h>

#include <asm/sections.h>

#include <asm/lowcore.h>

#include <asm/setup.h>

#include <asm/timex.h>

#include "entry.h"
@@ -32,26 +31,6 @@ static void __init reset_tod_clock(void) 
	S390_lowcore.last_update_clock = TOD_UNIX_EPOCH;

}



static void __init rescue_initrd(void)

{

	unsigned long min_initrd_addr = (unsigned long) _end + (4UL << 20);



	/*

	 * Just like in case of IPL from VM reader we make sure there is a

	 * gap of 4MB between end of kernel and start of initrd.

	 * That way we can also be sure that saving an NSS will succeed,

	 * which however only requires different segments.

	 */

	if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))

		return;

	if (!INITRD_START || !INITRD_SIZE)

		return;

	if (INITRD_START >= min_initrd_addr)

		return;

	memmove((void *) min_initrd_addr, (void *) INITRD_START, INITRD_SIZE);

	INITRD_START = min_initrd_addr;

}



static void __init clear_bss_section(void)

{

	memset(__bss_start, 0, __bss_stop - __bss_start);
@@ -60,6 +39,5 @@ static void __init clear_bss_section(void) 
void __init startup_init_nobss(void)

{

	reset_tod_clock();

	rescue_initrd();

	clear_bss_section();

}

arch/s390/kernel/vmlinux.lds.S

+1 −0
Original line number Diff line number Diff line
@@ -154,6 +154,7 @@ SECTIONS 
		QUAD(_stext)			/* default_lma */

		QUAD(startup_continue)		/* entry */

		QUAD(__bss_start - _stext)	/* image_size */

		QUAD(__bss_stop - __bss_start)	/* bss_size */

	}



	/* Debugging sections.	*/