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

From: David Hildenbrand <david@redhat.com>
To: Peter Maydell <peter.maydell@linaro.org>
Cc: Cornelia Huck <cohuck@redhat.com>,
	Riku Voipio <riku.voipio@iki.fi>,
	Richard Henderson <richard.henderson@linaro.org>,
	"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
	Laurent Vivier <laurent@vivier.eu>,
	qemu-s390x <qemu-s390x@nongnu.org>
Subject: Re: [Qemu-devel] [qemu-s390x] linux-user: s390x issue on Fedora 30 (dynamic library loader?)
Date: Mon, 19 Aug 2019 14:22:23 +0200	[thread overview]
Message-ID: <dff44ac1-10e7-285e-467d-8dfe8c7a469b@redhat.com> (raw)
In-Reply-To: <CAFEAcA9xbPGSezS60cg6WzqpDR1u38aE0bXL_6pLs+H1TK3Ddw@mail.gmail.com>

On 19.08.19 14:11, Peter Maydell wrote:
> On Sat, 17 Aug 2019 at 17:14, David Hildenbrand <david@redhat.com> wrote:
>>
>> 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)
> 
> I'm pretty sure the problem you've run into is a long standing
> bug in the glibc dynamic loader. It cannot cope with the ld.so.cache
> being for the wrong endianness. (Correct endianness but incorrect
> architecture it correctly detects and ignores). The result is that
> running a linux-user QEMU dynamic binary for big-endian on little-endian
> like this will crash in the dynamic loader unless you arrange that it can't
> find the host's ld.so.cache somehow, eg:
>  (a) run inside a chroot
>  (b) create an empty /etc/ld.so.cache file inside the -L directory
> 
> The ideal fix would be if somebody cared enough to track down
> and fix the ld.so bug.
> 
> Compare:
> https://bugs.launchpad.net/qemu/+bug/1701798
> https://bugs.launchpad.net/qemu/+bug/1835693
> 
> thanks
> -- PMM
> 

Thanks, running

"ldconfig -c etc/ld.so.cache -r ."

Seems to fix the issue for me. So you are sure the bug resides in glic
and not in the qemu-user pieces of the library loader?

-- 

Thanks,

David / dhildenb