librt symbol versioning breakage (was Re: Build failure, undefined reference to __mq_oshandle)

[Daniel Eischen]

On Mon, 30 Nov 2015, Konstantin Belousov wrote:

> On Sun, Nov 29, 2015 at 12:27:40PM -0500, Daniel Eischen wrote:
>> On Sun, 29 Nov 2015, Konstantin Belousov wrote:
>>
>>> On Sun, Nov 29, 2015 at 01:23:04AM -0500, Daniel Eischen wrote:
>>>>
>>>> So I found out that sometime in the last year or so, symbol versioning
>>>> for librt was broken and leaking symbols that shouldn't have been
>>>> leaked.  I've just committed a fix for this.
>>>>
>>>> Do a 'readelf -sw /usr/lib/librt.so.1 | grep GLOBAL | grep -v UND'
>>>> and see the non FBSD_foo symbols that shouldn't be there.
>>>
>>> I did the following on the librt from the HEAD of about month ago:
>>>
>>> pooma% ls -l netboot/sandy/usr/lib/librt.so.1
>>> -r--r--r--  1 root  wheel  23704 Oct 24 23:35 netboot/sandy/usr/lib/librt.so.1
>>>
>>> pooma% readelf -sw netboot/sandy/usr/lib/librt.so.1 | grep GLOBAL | grep -v UND | grep -v FBSDpriv | grep FBSD
>>>    97: 0000000000000000     0 OBJECT  GLOBAL DEFAULT  ABS FBSD_1.0
>>>
>>> But I think that your commit is the good change.
>>
>>
>> Can you check librt.so.1 in your buildworld temporary build
>> environment?
>>
>>    $ readelf -sW /usr/obj/usr/FreeBSD/svn/src/tmp/usr/lib/librt.so.1 \
>>       grep -v UND | grep GLOBAL
>>
>> There has to be a reason that tests/sys/mqueue/mqtest[3-4].c build
>> without error when they reference __mq_oshandle.  That symbol is
>> not exported from librt.
>>
>> Hmm, looks like libc and libthr are also the same (leaky) in the
>> temporary build environment (TBE).  So something broke when building
>> the TBE libraries.
>>
>> For r277320 on my system Jan 19, 2015, the TBE libraries must have
>> been built correctly because mqtests[3-4] failed with unresolved
>> references to __mq_oshandle.
>
> In fact, my command was wrong.  I see that there are indeed a lot of symbols
> exported which are not versioned (this is where my command was wrong, the
> grep FBSD part), even for the installed librt.

Arrgh, this bug also seems to have slipped into 10-stable.

$ uname -a
FreeBSD <elided> 10.1-RELEASE-p9 FreeBSD 10.1-RELEASE-p9 #0: Tue Apr  7 
01:09:46 UTC 2015 
root at amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC  amd64
$ readelf -sW /usr/lib/librt.so.1 | grep -v UND | grep GLOBAL \
   | grep -v FBSD
     71: 0000000000003ac0   432 FUNC    GLOBAL DEFAULT   12 __sigev_alloc
     ...
$ readelf -sW /usr/lib/librt.so.1 | grep -v UND | grep GLOBAL \
   | grep -v FBSD | wc -l
       22

-- 
DE