[glibc] nptl_db: disable DT_RELR on libthread_db.so

[glibc] nptl_db: disable DT_RELR on libthread_db.so

[Paul E. Murphy]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=aa13fd16183949bbc40b010552e2e42003ebee62

commit aa13fd16183949bbc40b010552e2e42003ebee62
Author: Paul E. Murphy <murphyp@linux.ibm.com>
Date:   Wed Jun 1 16:19:49 2022 +0000

    nptl_db: disable DT_RELR on libthread_db.so
    
    Some nptl tests inadvertently use the host's gdb to verify
    libthread_db.so, which is loaded with the host's runtime.  This causes
    a couple of test failures when the host glibc does not support DT_RELR.
    
    The not correct, but simple, workaround is to build without DT_RELR
    as this library is otherwise likely to load on glibc 2.17 and newer
    today.
    
    This allows tst-pthread-gdb-attach{,-static} to continue working
    when testing on a gdb loaded with an older glibc.
    
    This avoids a failure in tst-pthread-gdb-attach similar to:
    
      Trying host libthread_db library: .../build/glibc/nptl_db/libthread_db.so.1.
      dlopen failed: /lib64/libc.so.6: version `GLIBC_ABI_DT_RELR' not found (required by .../build/glibc/nptl_db/libthread_db.so.1).
    
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>

Diff:
---
 nptl_db/Makefile | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/nptl_db/Makefile b/nptl_db/Makefile
index ed923a41e5..2360e53c88 100644
--- a/nptl_db/Makefile
+++ b/nptl_db/Makefile
@@ -49,6 +49,12 @@ libthread_db-inhibit-o = $(filter-out .os,$(object-suffixes))
 # The ps_* callback functions are not defined.
 libthread_db.so-no-z-defs = yes
 
+# This is a hack.  This is not the correct solution.  When this glibc
+# is tested, the gdb used could be loaded by the host glibc, which
+# may not support DT_RELR, and report a failure instead of unsupported.
+# For now, build this without DT_RELR support to avoid this situation.
+libthread_db.so-no-dt-relr = yes
+
 tests-special += $(objpfx)db-symbols.out
 
 include ../Rules