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

   $ 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 r...@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

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