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s390/boot: block uncompressed vmlinux booting attempts

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Since the plain vmlinux ELF file no longer carries all necessary parts
for starting up (like the entry point and decompressor), add a check
which would block boot process and encourage users to use bzImage or
arch/s390/boot/compressed/vmlinux instead.

The check relies on s390 linux entry point ABI definition, which is only
present in bzImage and arch/s390/boot/compressed/vmlinux.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
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 2018-06-25 13:59:35 +02:00 committed by Martin Schwidefsky
parent 9acdb3bb07
commit 627c9b6205
3 changed files with 16 additions and 3 deletions
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4
arch/s390/boot/head.S
View File

@ -272,14 +272,14 @@ iplstart:
.org 0x10000
ENTRY(startup)
j .Lep_startup_normal
.org 0x10008
.org EP_OFFSET
#
# This is a list of s390 kernel entry points. At address 0x1000f the number of
# valid entry points is stored.
#
# IMPORTANT: Do not change this table, it is s390 kernel ABI!
#
.ascii "S390EP"
.ascii EP_STRING
.byte 0x00,0x01
#
# kdump startup-code at 0x10010, running in 64 bit absolute addressing mode

3
arch/s390/include/asm/setup.h
View File

@ -9,7 +9,8 @@
#include <linux/const.h>
#include <uapi/asm/setup.h>
#define EP_OFFSET 0x10008
#define EP_STRING "S390EP"
#define PARMAREA 0x10400
#define PARMAREA_END 0x11000

12
arch/s390/kernel/early.c
View File

@ -331,8 +331,20 @@ static void __init setup_boot_command_line(void)
append_to_cmdline(append_ipl_scpdata);
}
static void __init check_image_bootable(void)
{
if (!memcmp(EP_STRING, (void *)EP_OFFSET, strlen(EP_STRING)))
return;
sclp_early_printk("Linux kernel boot failure: An attempt to boot a vmlinux ELF image failed.\n");
sclp_early_printk("This image does not contain all parts necessary for starting up. Use\n");
sclp_early_printk("bzImage or arch/s390/boot/compressed/vmlinux instead.\n");
disabled_wait(0xbadb007);
}
void __init startup_init(void)
{
check_image_bootable();
time_early_init();
init_kernel_storage_key();
lockdep_off();