** Changed in: linux (Ubuntu)
Status: In Progress => Incomplete
** Changed in: linux (Ubuntu Bionic)
Status: In Progress => Incomplete
** Changed in: linux (Ubuntu Cosmic)
Status: In Progress => Incomplete
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https://bugs.launchpad.net/bugs/1799388
Title:
TM (Hardware Transactional Memory) instructions halt application on
baremetal POWER9 DD2.1
Status in The Ubuntu-power-systems project:
Incomplete
Status in linux package in Ubuntu:
Incomplete
Status in linux source package in Bionic:
Incomplete
Status in linux source package in Cosmic:
Incomplete
Bug description:
== Comment: #0 - Michael Ranweiler <[email protected]> - 2018-10-15
08:55:55 ==
+++ This bug was initially created as a clone of Bug #167756 +++
---Problem Description---
TM (Hardware Transactional Memory) instructions halt application on baremetal
POWER9 DD2.1
Contact Information = [email protected]
---Additional Hardware Info---
POWER9 DD2.1 (pvr 004e 1201) baremetal. Witherspoon.
Machine Type = POWER9 DD2.1 (pvr 004e 1201) baremetal
---Debugger---
A debugger is not configured
---Steps to Reproduce---
Currently TM (Hardware Transactional Memory) on baremetal POWER9 DD2.1 (pvr
004e 1201) with the latest firmware [1] (Firmware level [2] was also tested
with the same result) and running Linux from Linus' upstream tree [3] or
powerpc/next branch [4] is not working as expected. Once a TM instruction is
executed in a process (any instruction), the process halts completely and has
to be killed.
A simple test case is to execute a 'tend.' which accordingly to POWER8
behaviour and the ISA v3.00 if executed "in Non-transactional state is
treated as a no-op." [5]. It means that the instruction in the test
case below should be treated simply as a 'nop' instruction and the
process would terminate normally but instead it halts and the process
never terminates:
root@io83:~/gromero# cat t.c
int main() { asm ("tend.;"); }
root@io83:~/gromero# make t
make: 't' is up to date.
root@io83:~/gromero# ./t
^C
<CTRL-C was pressed to kill the process since PC got stuck at 'tend.'
instruction forever>
Ubuntu stock kernel 4.15.0-20-generic was also tested with the same
result.
I confirmed with Erich Hauptli (FW team) that FW stack levels [1]
contain all the TM fixes we have at the moment.
Thus, that issue affects any application that uses TM on a baremetal
POWER9 DD2.1 (pvr 004e 1201).
[1]
IBM-witherspoon-ibm-OP9_v1.19_1.160
op-build-v1.21.2-255-g6ad1636-dirty
buildroot-2017.11-5-g65679be
skiboot-v5.10.5-op910-1
hostboot-ed53939
linux-4.14.24-openpower1-paed97e8
petitboot-v1.6.6-p41a158a
machine-xml-22224af
occ-ef5d466
hostboot-binaries-6a92b6d
capp-ucode-p9-dd2-v3
sbe-7e02c23
[2]
open-power-witherspoon-v1.22-82-gebe1295-dirty
buildroot-2018.02.1-6-ga8d11267c2
skiboot-v6.0-rc1
hostboot-d9bf361-p6755b85
occ-f741c41
linux-4.16.7-openpower1-p945838d
petitboot-v1.7.1-pd695626
machine-xml-7cd20a6
hostboot-binaries-53aece6
capp-ucode-p9-dd2-v4
sbe-8e0105e
hcode-hw050318a.op920
[3] https://github.com/torvalds/linux.git (master)
[4] https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git (next)
[5] Power ISA - Book II, p. 894
Stack trace output:
no
Oops output:
no
Userspace tool common name: any tool using TM instruction set
Userspace rpm: not relevant
The userspace tool has the following bit modes: 64-bit
System Dump Info:
The system is not configured to capture a system dump.
Userspace tool obtained from project website: na
*Additional Instructions for [email protected]:
-Attach sysctl -a output output to the bug.
-Attach ltrace and strace of userspace application.
The following patch fixes this issue:
http://patchwork.ozlabs.org/patch/968375/
Author: Michael Neuling <[email protected]>
Date: Tue Sep 11 13:07:56 2018 +1000
powerpc/tm: Fix HFSCR bit for no suspend case
Currently on P9N DD2.1 we end up taking infinite TM facility
unavailable exceptions on the first TM usage by userspace.
In the special case of TM no suspend (P9N DD2.1), Linux is told TM is
off via CPU dt-ftrs but told to (partially) use it via
OPAL_REINIT_CPUS_TM_SUSPEND_DISABLED. So HFSCR[TM] will be off from
dt-ftrs but we need to turn it on for the no suspend case.
This patch fixes this by enabling HFSCR TM in this case.
Cc: [email protected] # 4.15+
Signed-off-by: Michael Neuling <[email protected]>
== Comment: #2 - Michael Ranweiler <[email protected]> - 2018-10-15
13:52:13 ==
This is in the powerpc -next branch:
https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=next&id=dd9a8c5a87395b6f05552c3b44e42fdc95760552
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