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From f73b18e03c6758500bf367b1575205772d1f878f Mon Sep 17 00:00:00 2001
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From: Thomas Huth <thuth@redhat.com>
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Date: Fri, 29 May 2020 05:53:52 -0400
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Subject: [PATCH 10/42] tests/boot-sector: Fix the bad s390x assembler code
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RH-Author: Thomas Huth <thuth@redhat.com>
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Message-id: <20200529055420.16855-11-thuth@redhat.com>
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Patchwork-id: 97031
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O-Subject: [RHEL-8.3.0 qemu-kvm PATCH v2 10/38] tests/boot-sector: Fix the bad s390x assembler code
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Bugzilla: 1828317
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RH-Acked-by: Claudio Imbrenda <cimbrend@redhat.com>
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RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
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RH-Acked-by: David Hildenbrand <david@redhat.com>
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There are currently two bugs in s390x_code[]: First, the initial jump
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uses the wrong offset, so it was jumping to 0x10014 instead of 0x10010.
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Second, LHI only loads the lower 32-bit of the register.
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Everything worked fine as long as the s390-ccw bios code was jumping
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here with r3 containing zeroes in the uppermost 48 bit - which just
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happened to be the case so far by accident. But we can not rely on this
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fact, and indeed one of the recent suggested patches to jump2ipl.c cause
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the newer GCCs to put different values into r3. In that case the code
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from s390x_code[] crashes very ungracefully.
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Thus let's make sure to jump to the right instruction, and use LGHI
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instead of LHI to make sure that we always zero out the upper bits
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of the register.
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Signed-off-by: Thomas Huth <thuth@redhat.com>
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Message-Id: <20191217150642.27946-1-thuth@redhat.com>
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Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
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Signed-off-by: Cornelia Huck <cohuck@redhat.com>
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(cherry picked from commit 5afec76fbe2c07d03fd8c9ac525140059499637a)
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Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
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---
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tests/boot-sector.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/tests/boot-sector.c b/tests/boot-sector.c
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index 7824286b9a..9e66c6d013 100644
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--- a/tests/boot-sector.c
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+++ b/tests/boot-sector.c
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@@ -75,11 +75,11 @@ static const uint8_t s390x_psw_and_magic[] = {
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0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40, 0x40 /* in the s390-ccw bios */
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};
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static const uint8_t s390x_code[] = {
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- 0xa7, 0xf4, 0x00, 0x0a, /* j 0x10010 */
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+ 0xa7, 0xf4, 0x00, 0x08, /* j 0x10010 */
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0x00, 0x00, 0x00, 0x00,
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'S', '3', '9', '0',
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'E', 'P', 0x00, 0x01,
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- 0xa7, 0x38, HIGH(SIGNATURE_ADDR), LOW(SIGNATURE_ADDR), /* lhi r3,0x7c10 */
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+ 0xa7, 0x39, HIGH(SIGNATURE_ADDR), LOW(SIGNATURE_ADDR), /* lghi r3,0x7c10 */
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0xa7, 0x48, LOW(SIGNATURE), HIGH(SIGNATURE), /* lhi r4,0xadde */
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0x40, 0x40, 0x30, 0x00, /* sth r4,0(r3) */
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0xa7, 0xf4, 0xff, 0xfa /* j 0x10010 */
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--
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2.27.0
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