[PATCH][BZ #21779] Resolve non-relocatable branch in MicroBlaze pt-vfork.S

[Nathan Rossi]

The relative branch directly to __libc_vfork results in an relocation
that cannot be resolved. Specifically a R_MICROBLAZE_64_PCREL relocation
is created for this branch, however for MicroBlaze R_MICROBLAZE_64_PCREL
type relocations symbols are not resolved. Additionally due to the
branch being located in the .text section the instruction cannot be
rewritten as the section is not writable, and causes a segfault at
runtime when loading libpthread.

To resolve this issue, ensure the branch is done using PLT. This removes
the need to modify the instruction and trades the R_MICROBLAZE_64_PCREL
for a more common R_MICROBLAZE_JUMP via the PLT.

2017-07-17  Nathan Rossi  <nathan@nathanrossi.com>

        [BZ #21779]
        * sysdeps/unix/sysv/linux/microblaze/pt-vfork.S: Branch using PLT
---
 sysdeps/unix/sysv/linux/microblaze/pt-vfork.S | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/unix/sysv/linux/microblaze/pt-vfork.S b/sysdeps/unix/sysv/linux/microblaze/pt-vfork.S
index f201f0429f..d8339f21f7 100644
--- a/sysdeps/unix/sysv/linux/microblaze/pt-vfork.S
+++ b/sysdeps/unix/sysv/linux/microblaze/pt-vfork.S
@@ -34,7 +34,7 @@
        || SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_20))
 
 ENTRY (vfork_compat)
-	bri	__libc_vfork
+	bri	__libc_vfork@PLT
 END (vfork_compat)
 
 #endif
-- 
2.13.2