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

[Konstantin Belousov]

On Thu, Dec 03, 2015 at 10:34:10PM -0500, Daniel Eischen wrote:
> 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

Yes, I did my check on stable/10 FWIW.