* [Qemu-devel] [Bug 1828867] [NEW] QEmu translation is incorrect when using REX in combination with LAHF/SAHF
@ 2019-05-13 17:30 Sonicadvance1
2019-05-13 17:31 ` [Qemu-devel] [Bug 1828867] " Sonicadvance1
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: Sonicadvance1 @ 2019-05-13 17:30 UTC (permalink / raw)
To: qemu-devel
Public bug reported:
When translating code that is using LAHF and SAHF in combination with the REX prefix then qemu translates incorrectly.
These two instructions only ever use the AH register. Contrary to other instructions where if you use REX + high bit offsets then it'll pull in rsp and a few other registers.
On hardware the REX prefix doesn't effect behaviour of these instructions at all.
QEMU incorrectly selects RSP as the register of choice here due to this combination of REX + AH register usage.
I've attached a patch that is super terrible just so I can work around
the issue locally and to sort of show off how it is to be "fixed"
** Affects: qemu
Importance: Undecided
Status: New
** Patch added: "Terrible terrible patch"
https://bugs.launchpad.net/bugs/1828867/+attachment/5263494/+files/lahf_sahf.diff
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https://bugs.launchpad.net/bugs/1828867
Title:
QEmu translation is incorrect when using REX in combination with
LAHF/SAHF
Status in QEMU:
New
Bug description:
When translating code that is using LAHF and SAHF in combination with the REX prefix then qemu translates incorrectly.
These two instructions only ever use the AH register. Contrary to other instructions where if you use REX + high bit offsets then it'll pull in rsp and a few other registers.
On hardware the REX prefix doesn't effect behaviour of these instructions at all.
QEMU incorrectly selects RSP as the register of choice here due to this combination of REX + AH register usage.
I've attached a patch that is super terrible just so I can work around
the issue locally and to sort of show off how it is to be "fixed"
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1828867/+subscriptions
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Qemu-devel] [Bug 1828867] Re: QEmu translation is incorrect when using REX in combination with LAHF/SAHF
2019-05-13 17:30 [Qemu-devel] [Bug 1828867] [NEW] QEmu translation is incorrect when using REX in combination with LAHF/SAHF Sonicadvance1
@ 2019-05-13 17:31 ` Sonicadvance1
2019-05-13 20:24 ` Alex Bennée
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Sonicadvance1 @ 2019-05-13 17:31 UTC (permalink / raw)
To: qemu-devel
Here's also a basic test that can be run on hardware and have rflags and
rsp inspected after each instruction just to see how hardware doesn't
effect it.
** Attachment added: "a.cpp"
https://bugs.launchpad.net/qemu/+bug/1828867/+attachment/5263495/+files/a.cpp
--
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1828867
Title:
QEmu translation is incorrect when using REX in combination with
LAHF/SAHF
Status in QEMU:
New
Bug description:
When translating code that is using LAHF and SAHF in combination with the REX prefix then qemu translates incorrectly.
These two instructions only ever use the AH register. Contrary to other instructions where if you use REX + high bit offsets then it'll pull in rsp and a few other registers.
On hardware the REX prefix doesn't effect behaviour of these instructions at all.
QEMU incorrectly selects RSP as the register of choice here due to this combination of REX + AH register usage.
I've attached a patch that is super terrible just so I can work around
the issue locally and to sort of show off how it is to be "fixed"
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1828867/+subscriptions
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Qemu-devel] [Bug 1828867] Re: QEmu translation is incorrect when using REX in combination with LAHF/SAHF
2019-05-13 17:30 [Qemu-devel] [Bug 1828867] [NEW] QEmu translation is incorrect when using REX in combination with LAHF/SAHF Sonicadvance1
2019-05-13 17:31 ` [Qemu-devel] [Bug 1828867] " Sonicadvance1
@ 2019-05-13 20:24 ` Alex Bennée
2021-04-22 6:15 ` Thomas Huth
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Alex Bennée @ 2019-05-13 20:24 UTC (permalink / raw)
To: qemu-devel
** Tags added: tcg testcase x86
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1828867
Title:
QEmu translation is incorrect when using REX in combination with
LAHF/SAHF
Status in QEMU:
New
Bug description:
When translating code that is using LAHF and SAHF in combination with the REX prefix then qemu translates incorrectly.
These two instructions only ever use the AH register. Contrary to other instructions where if you use REX + high bit offsets then it'll pull in rsp and a few other registers.
On hardware the REX prefix doesn't effect behaviour of these instructions at all.
QEMU incorrectly selects RSP as the register of choice here due to this combination of REX + AH register usage.
I've attached a patch that is super terrible just so I can work around
the issue locally and to sort of show off how it is to be "fixed"
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1828867/+subscriptions
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug 1828867] Re: QEmu translation is incorrect when using REX in combination with LAHF/SAHF
2019-05-13 17:30 [Qemu-devel] [Bug 1828867] [NEW] QEmu translation is incorrect when using REX in combination with LAHF/SAHF Sonicadvance1
2019-05-13 17:31 ` [Qemu-devel] [Bug 1828867] " Sonicadvance1
2019-05-13 20:24 ` Alex Bennée
@ 2021-04-22 6:15 ` Thomas Huth
2021-04-22 6:46 ` Ryan Houdek
2021-05-04 15:46 ` Thomas Huth
4 siblings, 0 replies; 6+ messages in thread
From: Thomas Huth @ 2021-04-22 6:15 UTC (permalink / raw)
To: qemu-devel
The QEMU project is currently considering to move its bug tracking to
another system. For this we need to know which bugs are still valid
and which could be closed already. Thus we are setting older bugs to
"Incomplete" now.
If you still think this bug report here is valid, then please switch
the state back to "New" within the next 60 days, otherwise this report
will be marked as "Expired". Or please mark it as "Fix Released" if
the problem has been solved with a newer version of QEMU already.
Thank you and sorry for the inconvenience.
** Changed in: qemu
Status: New => Incomplete
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1828867
Title:
QEmu translation is incorrect when using REX in combination with
LAHF/SAHF
Status in QEMU:
Incomplete
Bug description:
When translating code that is using LAHF and SAHF in combination with the REX prefix then qemu translates incorrectly.
These two instructions only ever use the AH register. Contrary to other instructions where if you use REX + high bit offsets then it'll pull in rsp and a few other registers.
On hardware the REX prefix doesn't effect behaviour of these instructions at all.
QEMU incorrectly selects RSP as the register of choice here due to this combination of REX + AH register usage.
I've attached a patch that is super terrible just so I can work around
the issue locally and to sort of show off how it is to be "fixed"
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1828867/+subscriptions
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug 1828867] Re: QEmu translation is incorrect when using REX in combination with LAHF/SAHF
2019-05-13 17:30 [Qemu-devel] [Bug 1828867] [NEW] QEmu translation is incorrect when using REX in combination with LAHF/SAHF Sonicadvance1
` (2 preceding siblings ...)
2021-04-22 6:15 ` Thomas Huth
@ 2021-04-22 6:46 ` Ryan Houdek
2021-05-04 15:46 ` Thomas Huth
4 siblings, 0 replies; 6+ messages in thread
From: Ryan Houdek @ 2021-04-22 6:46 UTC (permalink / raw)
To: qemu-devel
This is still relevant.
** Changed in: qemu
Status: Incomplete => New
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1828867
Title:
QEmu translation is incorrect when using REX in combination with
LAHF/SAHF
Status in QEMU:
New
Bug description:
When translating code that is using LAHF and SAHF in combination with the REX prefix then qemu translates incorrectly.
These two instructions only ever use the AH register. Contrary to other instructions where if you use REX + high bit offsets then it'll pull in rsp and a few other registers.
On hardware the REX prefix doesn't effect behaviour of these instructions at all.
QEMU incorrectly selects RSP as the register of choice here due to this combination of REX + AH register usage.
I've attached a patch that is super terrible just so I can work around
the issue locally and to sort of show off how it is to be "fixed"
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1828867/+subscriptions
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Bug 1828867] Re: QEmu translation is incorrect when using REX in combination with LAHF/SAHF
2019-05-13 17:30 [Qemu-devel] [Bug 1828867] [NEW] QEmu translation is incorrect when using REX in combination with LAHF/SAHF Sonicadvance1
` (3 preceding siblings ...)
2021-04-22 6:46 ` Ryan Houdek
@ 2021-05-04 15:46 ` Thomas Huth
4 siblings, 0 replies; 6+ messages in thread
From: Thomas Huth @ 2021-05-04 15:46 UTC (permalink / raw)
To: qemu-devel
This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'expired' now.
Please continue with the discussion here:
https://gitlab.com/qemu-project/qemu/-/issues/130
** Changed in: qemu
Status: New => Expired
** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #130
https://gitlab.com/qemu-project/qemu/-/issues/130
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1828867
Title:
QEmu translation is incorrect when using REX in combination with
LAHF/SAHF
Status in QEMU:
Expired
Bug description:
When translating code that is using LAHF and SAHF in combination with the REX prefix then qemu translates incorrectly.
These two instructions only ever use the AH register. Contrary to other instructions where if you use REX + high bit offsets then it'll pull in rsp and a few other registers.
On hardware the REX prefix doesn't effect behaviour of these instructions at all.
QEMU incorrectly selects RSP as the register of choice here due to this combination of REX + AH register usage.
I've attached a patch that is super terrible just so I can work around
the issue locally and to sort of show off how it is to be "fixed"
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1828867/+subscriptions
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-05-04 15:57 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
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2019-05-13 17:30 [Qemu-devel] [Bug 1828867] [NEW] QEmu translation is incorrect when using REX in combination with LAHF/SAHF Sonicadvance1
2019-05-13 17:31 ` [Qemu-devel] [Bug 1828867] " Sonicadvance1
2019-05-13 20:24 ` Alex Bennée
2021-04-22 6:15 ` Thomas Huth
2021-04-22 6:46 ` Ryan Houdek
2021-05-04 15:46 ` Thomas Huth
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