* [Qemu-devel] [Bug 1843795] [NEW] 'mtfsf' instruction can clear FI incorrectly
@ 2019-09-12 16:52 Paul Clarke
2019-09-12 18:32 ` [Qemu-devel] [Bug 1843795] " Alex Bennée
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Paul Clarke @ 2019-09-12 16:52 UTC (permalink / raw)
To: qemu-devel
Public bug reported:
Using mtfsf instruction can clear the FPSCR FI bit incorrectly. This code snippet exhibits the issue:
--
fpscr.ll = 0x1fffffff;
__builtin_mtfsf (0b11111111, fpscr.d);
fpscr.d = __builtin_mffs ();
--
On POWER9 hardware:
mffs : FPSCR = 0x000000007ffff7ff
On qemu (git master; "-cpu POWER9"):
--
$ ./mtfsf
mffs : FPSCR = 0x000000007ffdffff
--
Two differences:
bit 52: "reserved", so maybe a "don't care" case
bit 46: "FI"
$ git log -1 master
commit 89ea03a7dc83ca36b670ba7f787802791fcb04b1
Merge: 019217c 2531164
Author: Peter Maydell <peter.maydell@linaro.org>
Date: Mon Sep 9 09:48:34 2019 +0100
I tracked the clear is coming from do_float_check_status, likely the one
in gen_mtfsf, but then I get lost figuring out what _should_ be
happening. :-/
Test attached.
** Affects: qemu
Importance: Undecided
Status: New
** Attachment added: "test case - mtfsf clears FI"
https://bugs.launchpad.net/bugs/1843795/+attachment/5288363/+files/mtfsf.c
--
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https://bugs.launchpad.net/bugs/1843795
Title:
'mtfsf' instruction can clear FI incorrectly
Status in QEMU:
New
Bug description:
Using mtfsf instruction can clear the FPSCR FI bit incorrectly. This code snippet exhibits the issue:
--
fpscr.ll = 0x1fffffff;
__builtin_mtfsf (0b11111111, fpscr.d);
fpscr.d = __builtin_mffs ();
--
On POWER9 hardware:
mffs : FPSCR = 0x000000007ffff7ff
On qemu (git master; "-cpu POWER9"):
--
$ ./mtfsf
mffs : FPSCR = 0x000000007ffdffff
--
Two differences:
bit 52: "reserved", so maybe a "don't care" case
bit 46: "FI"
$ git log -1 master
commit 89ea03a7dc83ca36b670ba7f787802791fcb04b1
Merge: 019217c 2531164
Author: Peter Maydell <peter.maydell@linaro.org>
Date: Mon Sep 9 09:48:34 2019 +0100
I tracked the clear is coming from do_float_check_status, likely the
one in gen_mtfsf, but then I get lost figuring out what _should_ be
happening. :-/
Test attached.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1843795/+subscriptions
^ permalink raw reply [flat|nested] 5+ messages in thread* [Qemu-devel] [Bug 1843795] Re: 'mtfsf' instruction can clear FI incorrectly
2019-09-12 16:52 [Qemu-devel] [Bug 1843795] [NEW] 'mtfsf' instruction can clear FI incorrectly Paul Clarke
@ 2019-09-12 18:32 ` Alex Bennée
2021-04-22 7:32 ` Thomas Huth
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Alex Bennée @ 2019-09-12 18:32 UTC (permalink / raw)
To: qemu-devel
** Tags added: fpu ppc testcase
--
You received this bug notification because you are a member of qemu-
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https://bugs.launchpad.net/bugs/1843795
Title:
'mtfsf' instruction can clear FI incorrectly
Status in QEMU:
New
Bug description:
Using mtfsf instruction can clear the FPSCR FI bit incorrectly. This code snippet exhibits the issue:
--
fpscr.ll = 0x1fffffff;
__builtin_mtfsf (0b11111111, fpscr.d);
fpscr.d = __builtin_mffs ();
--
On POWER9 hardware:
mffs : FPSCR = 0x000000007ffff7ff
On qemu (git master; "-cpu POWER9"):
--
$ ./mtfsf
mffs : FPSCR = 0x000000007ffdffff
--
Two differences:
bit 52: "reserved", so maybe a "don't care" case
bit 46: "FI"
$ git log -1 master
commit 89ea03a7dc83ca36b670ba7f787802791fcb04b1
Merge: 019217c 2531164
Author: Peter Maydell <peter.maydell@linaro.org>
Date: Mon Sep 9 09:48:34 2019 +0100
I tracked the clear is coming from do_float_check_status, likely the
one in gen_mtfsf, but then I get lost figuring out what _should_ be
happening. :-/
Test attached.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1843795/+subscriptions
^ permalink raw reply [flat|nested] 5+ messages in thread* [Bug 1843795] Re: 'mtfsf' instruction can clear FI incorrectly
2019-09-12 16:52 [Qemu-devel] [Bug 1843795] [NEW] 'mtfsf' instruction can clear FI incorrectly Paul Clarke
2019-09-12 18:32 ` [Qemu-devel] [Bug 1843795] " Alex Bennée
@ 2021-04-22 7:32 ` Thomas Huth
2021-04-22 15:27 ` Paul Clarke
2021-05-11 5:37 ` Thomas Huth
3 siblings, 0 replies; 5+ messages in thread
From: Thomas Huth @ 2021-04-22 7:32 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-
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https://bugs.launchpad.net/bugs/1843795
Title:
'mtfsf' instruction can clear FI incorrectly
Status in QEMU:
Incomplete
Bug description:
Using mtfsf instruction can clear the FPSCR FI bit incorrectly. This code snippet exhibits the issue:
--
fpscr.ll = 0x1fffffff;
__builtin_mtfsf (0b11111111, fpscr.d);
fpscr.d = __builtin_mffs ();
--
On POWER9 hardware:
mffs : FPSCR = 0x000000007ffff7ff
On qemu (git master; "-cpu POWER9"):
--
$ ./mtfsf
mffs : FPSCR = 0x000000007ffdffff
--
Two differences:
bit 52: "reserved", so maybe a "don't care" case
bit 46: "FI"
$ git log -1 master
commit 89ea03a7dc83ca36b670ba7f787802791fcb04b1
Merge: 019217c 2531164
Author: Peter Maydell <peter.maydell@linaro.org>
Date: Mon Sep 9 09:48:34 2019 +0100
I tracked the clear is coming from do_float_check_status, likely the
one in gen_mtfsf, but then I get lost figuring out what _should_ be
happening. :-/
Test attached.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1843795/+subscriptions
^ permalink raw reply [flat|nested] 5+ messages in thread* [Bug 1843795] Re: 'mtfsf' instruction can clear FI incorrectly
2019-09-12 16:52 [Qemu-devel] [Bug 1843795] [NEW] 'mtfsf' instruction can clear FI incorrectly Paul Clarke
2019-09-12 18:32 ` [Qemu-devel] [Bug 1843795] " Alex Bennée
2021-04-22 7:32 ` Thomas Huth
@ 2021-04-22 15:27 ` Paul Clarke
2021-05-11 5:37 ` Thomas Huth
3 siblings, 0 replies; 5+ messages in thread
From: Paul Clarke @ 2021-04-22 15:27 UTC (permalink / raw)
To: qemu-devel
** 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/1843795
Title:
'mtfsf' instruction can clear FI incorrectly
Status in QEMU:
New
Bug description:
Using mtfsf instruction can clear the FPSCR FI bit incorrectly. This code snippet exhibits the issue:
--
fpscr.ll = 0x1fffffff;
__builtin_mtfsf (0b11111111, fpscr.d);
fpscr.d = __builtin_mffs ();
--
On POWER9 hardware:
mffs : FPSCR = 0x000000007ffff7ff
On qemu (git master; "-cpu POWER9"):
--
$ ./mtfsf
mffs : FPSCR = 0x000000007ffdffff
--
Two differences:
bit 52: "reserved", so maybe a "don't care" case
bit 46: "FI"
$ git log -1 master
commit 89ea03a7dc83ca36b670ba7f787802791fcb04b1
Merge: 019217c 2531164
Author: Peter Maydell <peter.maydell@linaro.org>
Date: Mon Sep 9 09:48:34 2019 +0100
I tracked the clear is coming from do_float_check_status, likely the
one in gen_mtfsf, but then I get lost figuring out what _should_ be
happening. :-/
Test attached.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1843795/+subscriptions
^ permalink raw reply [flat|nested] 5+ messages in thread* [Bug 1843795] Re: 'mtfsf' instruction can clear FI incorrectly
2019-09-12 16:52 [Qemu-devel] [Bug 1843795] [NEW] 'mtfsf' instruction can clear FI incorrectly Paul Clarke
` (2 preceding siblings ...)
2021-04-22 15:27 ` Paul Clarke
@ 2021-05-11 5:37 ` Thomas Huth
3 siblings, 0 replies; 5+ messages in thread
From: Thomas Huth @ 2021-05-11 5:37 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/266
** Changed in: qemu
Status: New => Expired
** Bug watch added: gitlab.com/qemu-project/qemu/-/issues #266
https://gitlab.com/qemu-project/qemu/-/issues/266
--
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1843795
Title:
'mtfsf' instruction can clear FI incorrectly
Status in QEMU:
Expired
Bug description:
Using mtfsf instruction can clear the FPSCR FI bit incorrectly. This code snippet exhibits the issue:
--
fpscr.ll = 0x1fffffff;
__builtin_mtfsf (0b11111111, fpscr.d);
fpscr.d = __builtin_mffs ();
--
On POWER9 hardware:
mffs : FPSCR = 0x000000007ffff7ff
On qemu (git master; "-cpu POWER9"):
--
$ ./mtfsf
mffs : FPSCR = 0x000000007ffdffff
--
Two differences:
bit 52: "reserved", so maybe a "don't care" case
bit 46: "FI"
$ git log -1 master
commit 89ea03a7dc83ca36b670ba7f787802791fcb04b1
Merge: 019217c 2531164
Author: Peter Maydell <peter.maydell@linaro.org>
Date: Mon Sep 9 09:48:34 2019 +0100
I tracked the clear is coming from do_float_check_status, likely the
one in gen_mtfsf, but then I get lost figuring out what _should_ be
happening. :-/
Test attached.
To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1843795/+subscriptions
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-05-11 5:56 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-09-12 16:52 [Qemu-devel] [Bug 1843795] [NEW] 'mtfsf' instruction can clear FI incorrectly Paul Clarke
2019-09-12 18:32 ` [Qemu-devel] [Bug 1843795] " Alex Bennée
2021-04-22 7:32 ` Thomas Huth
2021-04-22 15:27 ` Paul Clarke
2021-05-11 5:37 ` Thomas Huth
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