| Message ID | 20171122142627.73170-3-borntraeger@de.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | s390x fixes (post 2.11) | expand |
On Wed, 22 Nov 2017 15:26:27 +0100 Christian Borntraeger <borntraeger@de.ibm.com> wrote: > The QEMU ELF loader does not zero the bss segment. > This resulted in several bugs, e.g. see > > commit 5d739a4787a5 (s390-ccw.img: Fix sporadic errors with ccw boot image - initialize css) > commit 6a40fa2669d3 (s390-ccw.img: Initialize next_idx) > commit 8775d91a0f42 (pc-bios/s390-ccw: Fix problem with invalid virtio-scsi LUN when rebooting) > > Lets fix this once and forever by letting the BIOS zero the bss itself. s/Lets/Let's/ :) > > Suggested-by: Alexander Graf <agraf@suse.de> > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> > --- > pc-bios/s390-ccw/start.S | 30 +++++++++++++++++++++++++++--- > 1 file changed, 27 insertions(+), 3 deletions(-) > > diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S > index 43f9bd2..eb8d024 100644 > --- a/pc-bios/s390-ccw/start.S > +++ b/pc-bios/s390-ccw/start.S > @@ -3,7 +3,7 @@ > * into the pc-bios directory of qemu. > * > * Copyright (c) 2013 Alexander Graf <agraf@suse.de> > - * Copyright 2013 IBM Corp. > + * 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 > @@ -13,8 +13,32 @@ > .globl _start > _start: > > -larl %r15, stack + 0x8000 /* Set up stack */ > -j main /* And call C */ > + 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) This looks like the right thing to do.
On 22.11.2017 15:26, Christian Borntraeger wrote: > The QEMU ELF loader does not zero the bss segment. > This resulted in several bugs, e.g. see > > commit 5d739a4787a5 (s390-ccw.img: Fix sporadic errors with ccw boot image - initialize css) > commit 6a40fa2669d3 (s390-ccw.img: Initialize next_idx) > commit 8775d91a0f42 (pc-bios/s390-ccw: Fix problem with invalid virtio-scsi LUN when rebooting) > > Lets 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> > --- > pc-bios/s390-ccw/start.S | 30 +++++++++++++++++++++++++++--- > 1 file changed, 27 insertions(+), 3 deletions(-) > > diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S > index 43f9bd2..eb8d024 100644 > --- a/pc-bios/s390-ccw/start.S > +++ b/pc-bios/s390-ccw/start.S > @@ -3,7 +3,7 @@ > * into the pc-bios directory of qemu. > * > * Copyright (c) 2013 Alexander Graf <agraf@suse.de> > - * Copyright 2013 IBM Corp. > + * 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 > @@ -13,8 +13,32 @@ > .globl _start > _start: > > -larl %r15, stack + 0x8000 /* Set up stack */ > -j main /* And call C */ > + 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) Wow, with EXECUTE :-) > +done: > + j main /* And call C */ > + > +memsetxc: > + xc 0(1,%r1),0(%r1) > + > > /* > * void disabled_wait(void) > Looks good to me: Reviewed-by: Thomas Huth <thuth@redhat.com>
On 11/22/2017 03:26 PM, Christian Borntraeger wrote: > The QEMU ELF loader does not zero the bss segment. > This resulted in several bugs, e.g. see > > commit 5d739a4787a5 (s390-ccw.img: Fix sporadic errors with ccw boot image - initialize css) > commit 6a40fa2669d3 (s390-ccw.img: Initialize next_idx) > commit 8775d91a0f42 (pc-bios/s390-ccw: Fix problem with invalid virtio-scsi LUN when rebooting) > > Lets 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> > --- > pc-bios/s390-ccw/start.S | 30 +++++++++++++++++++++++++++--- > 1 file changed, 27 insertions(+), 3 deletions(-) Reviewed-by: Richard Henderson <richard.henderson@linaro.org> r~
diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S index 43f9bd2..eb8d024 100644 --- a/pc-bios/s390-ccw/start.S +++ b/pc-bios/s390-ccw/start.S @@ -3,7 +3,7 @@ * into the pc-bios directory of qemu. * * Copyright (c) 2013 Alexander Graf <agraf@suse.de> - * Copyright 2013 IBM Corp. + * 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 @@ -13,8 +13,32 @@ .globl _start _start: -larl %r15, stack + 0x8000 /* Set up stack */ -j main /* And call C */ + 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)
The QEMU ELF loader does not zero the bss segment. This resulted in several bugs, e.g. see commit 5d739a4787a5 (s390-ccw.img: Fix sporadic errors with ccw boot image - initialize css) commit 6a40fa2669d3 (s390-ccw.img: Initialize next_idx) commit 8775d91a0f42 (pc-bios/s390-ccw: Fix problem with invalid virtio-scsi LUN when rebooting) Lets 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> --- pc-bios/s390-ccw/start.S | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-)