Re: [Qemu-devel] [qemu-s390x] linux-user: s390x issue on Fedora 30 (dynamic library loader?)

[David Hildenbrand]

On 17.08.19 18:22, Laurent Vivier wrote:
> Le 17/08/2019 à 18:14, David Hildenbrand a écrit :
>> On 17.08.19 17:59, David Hildenbrand wrote:
>>> Hi everybody,
>>>
>>> I was just trying to run qemu-s390x (linux-user) with a very simple
>>> binary (gzip + lib/ld64.so.1, compiled under Fedora 27). This used to
>>> work just fine a while ago (especially when I was working on vector
>>> instructions using QEMU v3.1). However, now I can't get past a SEGFAULT
>>> in the dynamic library loader (I assume it is trying to locate glibc). I
>>> tried a couple of other binaries that definitely used to work (from
>>> Fedora 30).
>>>
>>> I checked QEMU v4.1, v4.0 and v3.1. All are broken for me. Which is
>>> weird - because it used to work :/
>>>
>>> I remember that I was running Fedora 29 the last time I had it running,
>>> so my gut feeling is that this is related to some other system library
>>> (but which?). I am running on an up-to-date Fedora 30 x86-64 now.
>>>
>>> Any ideas? Has this been reported already? (not sure if this is a Fedora
>>> 30 issue)
>>>
>>> LANG=C ~/git/qemu/s390x-linux-user/qemu-s390x -d in_asm -L . gzip --help
>>>
>>> ----------------
>>> IN: _dl_load_cache_lookup
>>> 0x00000040008854c2:  larl       %r1,0x4000895030
>>> 0x00000040008854c8:  lg %r8,264(%r11)
>>> 0x00000040008854ce:  mvghi      0(%r1),-1
>>> 0x00000040008854d4:  la %r3,0(%r3,%r8)
>>> 0x00000040008854d8:  l  %r7,12(%r8)
>>> 0x00000040008854dc:  llgfr      %r2,%r7
>>> 0x00000040008854e0:  sllg       %r1,%r2,1
>>> 0x00000040008854e6:  agr        %r1,%r2
>>> 0x00000040008854ea:  sllg       %r1,%r1,2
>>> 0x00000040008854f0:  la %r6,16(%r1,%r8)
>>> 0x00000040008854f4:  sgr        %r3,%r6
>>> 0x00000040008854f8:  stg        %r3,256(%r11)
>>> 0x00000040008854fe:  ahi        %r7,-1
>>> 0x0000004000885502:  jl 0x40008850f0
>>>
>>> ----------------
>>> IN: _dl_load_cache_lookup
>>> 0x0000004000885506:  srak       %r10,%r7,1
>>> 0x000000400088550c:  lgfr       %r2,%r10
>>> 0x0000004000885510:  sllg       %r1,%r2,1
>>> 0x0000004000885516:  agr        %r1,%r2
>>> 0x000000400088551a:  sllg       %r1,%r1,2
>>> 0x0000004000885520:  l  %r1,20(%r1,%r8)
>>> 0x0000004000885524:  clrjhe     %r1,%r3,0x40008850f0
>>>
>>> Segmentation fault (Speicherabzug geschrieben)
>>>
>>>
>>> Core was generated by
>>> `/home/dhildenb/git/qemu/s390x-linux-user/qemu-s390x -d in_asm -L . gzip
>>> --help'.
>>> Program terminated with signal SIGSEGV, Segmentation fault.
>>> #0  0x00007fdc5d7c3232 in sigsuspend () from /lib64/libc.so.6
>>> [Current thread is 1 (Thread 0x7fdc5d7127c0 (LWP 31072))]
>>> Missing separate debuginfos, use: dnf debuginfo-install
>>> glib2-2.60.6-1.fc30.x86_64 glibc-2.29-15.fc30.x86_64
>>> libgcc-9.1.1-1.fc30.x86_64 libstdc++-9.1.1-1.fc30.x86_64
>>> pcre-8.43-2.fc30.x86_64 zlib-1.2.11-16.fc30.x86_64
>>> (gdb) bt
>>> #0  0x00007fdc5d7c3232 in sigsuspend () from /lib64/libc.so.6
>>> #1  0x000055f826135a9c in dump_core_and_abort
>>> (target_sig=target_sig@entry=11)
>>>     at /home/dhildenb/git/qemu/linux-user/signal.c:613
>>> #2  0x000055f826135e37 in handle_pending_signal
>>> (cpu_env=cpu_env@entry=0x55f8292cec48, sig=sig@entry=11,
>>>     k=k@entry=0x55f8292d7df0) at
>>> /home/dhildenb/git/qemu/linux-user/signal.c:877
>>> #3  0x000055f826136edd in process_pending_signals
>>> (cpu_env=cpu_env@entry=0x55f8292cec48)
>>>     at /home/dhildenb/git/qemu/linux-user/signal.c:953
>>> #4  0x000055f82613a13a in cpu_loop (env=0x55f8292cec48) at
>>> /home/dhildenb/git/qemu/linux-user/s390x/cpu_loop.c:150
>>> #5  0x000055f8260ce2ba in main (argc=<optimized out>,
>>> argv=0x7fff587a69d8, envp=<optimized out>)
>>>     at /home/dhildenb/git/qemu/linux-user/main.c:819
>>>
>>> Thanks!
>>>
>>
>> CCing QEMU-devel + use my proper dev mail address (I need more coffee :))
>>
> 
> I generally test qemu-s390x before my PR. Last time, I have tested with
> Fedora 30 x86_64 but my target are always debian.

What puzzles me is that it used to work just fine about 3-4 months ago.
I still have the binaries/libs lying around that I used back then (when
debugging a vector instruction-related issue). Whatever binary/QEMU
version I try now, it keeps segfaulting.

Via qemu-system-s390x, inside a Fedora guest, the binaries work
perfectly fine. So I really suspect that this has to do with my host system.

> 
> So I guess the problem is with the target.
> 
> I will have a look on Monday.

Thanks!

> 
> Thanks,
> Laurent
> 


-- 

Thanks,

David / dhildenb