** Description changed:
+ SRU Bug Template:
+ =================
+
+ [Impact]
+
+ * There is an endianess problem in pid_memory_read that impacts s390x.
+
+ * Due to this elfutils biarch test fails on s390x doing unwinding for a
+ 32 bit process.
+
+ [Fix]
+
+ * e4d985a3c1c873f77d20fa0cd421458cc2824996 e4d985a3 "IBM Z: Fix endianess
problem in pid_memory_read"
+
+ [Test Case]
+
+ * Have an Ubuntu Server 20.10 system or newer installed on LPAR, z/VM or KVM
that comes with elfutils 0.181 or 0.182.
+
+ * Run the test script: 'run-backtrace-native-biarch.sh'
+
+ * It either core dumps without the patch in place - look for
"/test-subr.sh: line 84: 376822 Aborted (core dumped)" or succeeds.
+
+ [Where problems could occur]
+
+ * If the translation is not done right (shift of the upper 4 bytes + down on
big endian 64 bit targets) the situation is broken in the same way, and things
stay the same.
+
+ * But in worst case the changes in 'pid_memory_read' of
/libdwfl/linux-pid-attach.c could have a negative impact even on architectures
other than s390x, in case the check for the endiness is wrong.
+
+ * But the changes are quite traceable and the additional code that fixes the
endianess problem is really only active on a big endian architecture.
+
+ [Other]
+
+ * The fix is upstream accepted with elfutils > 0.182.
+ __________
+
---Problem Description---
libdw unwinding fails for 32 bit binaries.
-
- Elfutils biarch test currently fails on s390x doing unwinding for a 32 bit
process.
+
+ Elfutils biarch test currently fails on s390x doing unwinding for a 32
+ bit process.
FAIL: run-backtrace-native-biarch.sh
====================================
0x557e7000 0x557eb000 /root/elfutils/tests/backtrace-child-biarch
0x7dba4000 0x7dd51000 /usr/lib/libc-2.32.so
0x7dd53000 0x7dd70000 /usr/lib/libpthread-2.32.so
0x7dd7f000 0x7dda6000 /usr/lib/ld-2.32.so
TID 376858:
# 0 0x7dd6668a raise
# 1 0x7fd0ef60 - 1 <null>
/root/elfutils/tests/backtrace: dwfl_thread_getframes: No DWARF information
found
backtrace: backtrace.c:114: callback_verify: Assertion `symname != NULL &&
strcmp (symname, "sigusr2") == 0' failed.
./test-subr.sh: line 84: 376822 Aborted (core dumped)
LD_LIBRARY_PATH="${built_library_path}${LD_LIBRARY_PATH:+:}$LD_LIBRARY_PATH"
$VALGRIND_CMD "$@"
backtrace-child-biarch: no main
FAIL run-backtrace-native-biarch.sh (exit status: 1)
Patch has already been posted and upstream committed:
https://sourceware.org/pipermail/elfutils-devel/2020q4/003149.html
Please pick up the following commit for the next release:
commit e4d985a3c1c873f77d20fa0cd421458cc2824996
Author: Andreas Krebbel <[email protected]>
Date: Thu Nov 19 20:32:24 2020 +0100
- IBM Z: Fix endianess problem in pid_memory_read
-
- The cached reads lack the big endian adjustments done in the fallback
- path.
-
- Signed-off-by: Andreas Krebbel <[email protected]>
+ IBM Z: Fix endianess problem in pid_memory_read
+ The cached reads lack the big endian adjustments done in the fallback
+ path.
+
+ Signed-off-by: Andreas Krebbel <[email protected]>
The patch applies cleanly ontop of elfutils_0.181-1.
====
strace right now is not built with unwinding support for IBM Z although both
variants should work - libdw and libunwind.
Other distros use libdw from elfutils while Ubuntu on x86 appears to use
libunwind. libdw and libunwind do support IBM Z.
It would be good to build strace with unwinding support for Z.
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/1908756
Title:
Ubuntu 20.10 - elfutils unwinding broken for s390 compat
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu-z-systems/+bug/1908756/+subscriptions
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
