qemu/pc-bios/s390-ccw/start.S
Christian Borntraeger 339686a358 pc-bios/s390-ccw: zero out bss section
The QEMU ELF loader does not zero the bss segment.
This resulted in several bugs, e.g. see

commit 5d739a4787 (s390-ccw.img: Fix sporadic errors with ccw boot image - initialize css)
commit 6a40fa2669d3 (s390-ccw.img: Initialize next_idx)
commit 8775d91a0f (pc-bios/s390-ccw: Fix problem with invalid virtio-scsi LUN when rebooting)

Let's fix this once and forever by letting the BIOS zero the bss itself.

Suggested-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Message-Id: <20171122142627.73170-3-borntraeger@de.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
2017-12-14 17:56:54 +01:00

88 lines
1.9 KiB
ArmAsm

/*
* First stage boot loader for virtio devices. The compiled output goes
* into the pc-bios directory of qemu.
*
* Copyright (c) 2013 Alexander Graf <agraf@suse.de>
* Copyright IBM Corp. 2013, 2017
*
* This work is licensed under the terms of the GNU GPL, version 2 or (at
* your option) any later version. See the COPYING file in the top-level
* directory.
*/
.globl _start
_start:
larl %r15, stack + 0x8000 /* Set up stack */
/* clear bss */
larl %r2, __bss_start
larl %r3, _end
slgr %r3, %r2 /* get sizeof bss */
ltgr %r3,%r3 /* bss emtpy? */
jz done
aghi %r3,-1
srlg %r4,%r3,8 /* how many 256 byte chunks? */
ltgr %r4,%r4
lgr %r1,%r2
jz remainder
loop:
xc 0(256,%r1),0(%r1)
la %r1,256(%r1)
brctg %r4,loop
remainder:
larl %r2,memsetxc
ex %r3,0(%r2)
done:
j main /* And call C */
memsetxc:
xc 0(1,%r1),0(%r1)
/*
* void disabled_wait(void)
*
* stops the current guest cpu.
*/
.globl disabled_wait
disabled_wait:
larl %r1,disabled_wait_psw
lpswe 0(%r1)
/*
* void consume_sclp_int(void)
*
* eats one sclp interrupt
*/
.globl consume_sclp_int
consume_sclp_int:
/* enable service interrupts in cr0 */
stctg 0,0,0(15)
oi 6(15), 0x2
lctlg 0,0,0(15)
/* prepare external call handler */
larl %r1, external_new_code
stg %r1, 0x1b8
larl %r1, external_new_mask
mvc 0x1b0(8),0(%r1)
/* load enabled wait PSW */
larl %r1, enabled_wait_psw
lpswe 0(%r1)
external_new_code:
/* disable service interrupts in cr0 */
stctg 0,0,0(15)
ni 6(15), 0xfd
lctlg 0,0,0(15)
br 14
.align 8
disabled_wait_psw:
.quad 0x0002000180000000,0x0000000000000000
enabled_wait_psw:
.quad 0x0302000180000000,0x0000000000000000
external_new_mask:
.quad 0x0000000180000000