glibc: Fix up MicroBlaze pt-vfork compat symbols

A bug has been present in glibc for a while where a symbol is emitted in
libpthread.so which is corrupt. Whilst previously this has not been an
issue due to how binutils has handled it, recent binutils behaviour has
changed enough to make this bug surface as a linker error.

Depending on the host (behaviour and native dependencies) the cross
binutils that is built may emit different values for the corrupt symbol.
This appears as an error similar to the following when linking against
libpthread.so (e.g. librt links against libpthread in glibc):

    invalid string offset 1843814912 >= 4913 for section `.dynstr'

This patch fixes up the symbols emitted for libpthread.so without
breaking any libpthread or libc ABI. See the glibc patch for more
specifics.

Signed-off-by: Nathan Rossi <nathan@nathanrossi.com>

3 files changed, 113 insertions, 0 deletions

diff --git a/recipes-microblaze/glibc/files/MicroBlaze-fix-up-pt-vfork-symbol-definitions.patch b/recipes-microblaze/glibc/files/MicroBlaze-fix-up-pt-vfork-symbol-definitions.patch
new file mode 100644
index 00000000..ed37d634
--- /dev/null
+++ b/recipes-microblaze/glibc/files/MicroBlaze-fix-up-pt-vfork-symbol-definitions.patch
@@ -0,0 +1,105 @@
+From 873fc4bf58d6cc8d579a65224350ce3adddc6c2a Mon Sep 17 00:00:00 2001
+From: Nathan Rossi <nathan@nathanrossi.com>
+Date: Wed, 23 Nov 2016 22:30:29 +1000
+Subject: [PATCH] MicroBlaze: fix up pt-vfork symbol definitions
+
+Due to the reuse of the alpha/pt-vfork.S implementation additional
+symbols are emitted for libpthread which are invalid due to the
+non-existence of a '__libc_vfork' symbol/implementation. A symbol is
+emitted which references __libc_vfork and is invalid which causes the
+linker to emit a corrupt symbol entry:
+
+    180: 00000000 0x24a91 NOTYPE  LOCAL  DEFAULT  UND <corrupt>
+
+Depending on the internals of the linker this corrupt symbol is either a
+valid symbol as above or an completely invalid symbol that causes issues
+when linking against libpthread.so:
+
+    179: 0000564b 0x825fd688 <OS specific>: 11 <unknown>: 4 HIDDEN
+        [<other>: 54]   UND <corrupt>
+
+In both cases this is the 'vfork@GLIBC_2.18' compat_symbol which is
+aliased as the local '__libc_vfork'. (in libpthread.so)
+
+    12: 00000000     0 NOTYPE  GLOBAL DEFAULT  UND vfork@GLIBC_2.18
+
+Due to how MicroBlaze differs from other architectures, it is special in
+that it only implements '__vfork' and due to the weak_alias in vfork.S
+also defines 'vfork' for both libc and libpthread. No other symbols
+(e.g. '__vfork_compat') are part of the ABI.
+
+This change removes the compatible symbol generation provided by
+alpha/pt-vfork.S and sets up the 'vfork' and '__vfork' symbols to be
+provided in libpthread based on SHLIB_COMPAT. This avoids the generation
+of invalid symbols but maintains the expected libc and libpthread vfork
+ABIs.
+
+Signed-off-by: Nathan Rossi <nathan@nathanrossi.com>
+Upstream-Status: Pending
+---
+ sysdeps/unix/sysv/linux/microblaze/pt-vfork.S | 40 ++++++++++++++++++++++++++-
+ sysdeps/unix/sysv/linux/microblaze/vfork.S    |  4 ++-
+ 2 files changed, 42 insertions(+), 2 deletions(-)
+
+diff --git a/sysdeps/unix/sysv/linux/microblaze/pt-vfork.S b/sysdeps/unix/sysv/linux/microblaze/pt-vfork.S
+index 65cc3823ac..82bc36eecc 100644
+--- a/sysdeps/unix/sysv/linux/microblaze/pt-vfork.S
++++ b/sysdeps/unix/sysv/linux/microblaze/pt-vfork.S
+@@ -1 +1,39 @@
+-#include <sysdeps/unix/sysv/linux/alpha/pt-vfork.S>
++/* vfork ABI-compatibility entry points for libpthread.
++   Copyright (C) 2014-2016 Free Software Foundation, Inc.
++   This file is part of the GNU C Library.
++
++   The GNU C Library is free software; you can redistribute it and/or
++   modify it under the terms of the GNU Lesser General Public
++   License as published by the Free Software Foundation; either
++   version 2.1 of the License, or (at your option) any later version.
++
++   The GNU C Library is distributed in the hope that it will be useful,
++   but WITHOUT ANY WARRANTY; without even the implied warranty of
++   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
++   Lesser General Public License for more details.
++
++   You should have received a copy of the GNU Lesser General Public
++   License along with the GNU C Library; if not, see
++   <http://www.gnu.org/licenses/>.  */
++
++#include <shlib-compat.h>
++
++/* libpthread used to have its own vfork implementation that differed
++   from libc's only in having a pointless micro-optimization.  There
++   is no longer any use to having a separate copy in libpthread, but
++   the historical ABI requires it.  For static linking, there is no
++   need to provide anything here--the libc version will be linked in.
++   For shared library ABI compatibility, there must be __vfork and
++   vfork symbols in libpthread.so.  */
++
++#if (SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_20) \
++     || SHLIB_COMPAT (libpthread, GLIBC_2_1_2, GLIBC_2_20))
++
++#include <vfork.S>
++
++#endif
++
++#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_20)
++weak_alias (__vfork, vfork)
++#endif
++
+diff --git a/sysdeps/unix/sysv/linux/microblaze/vfork.S b/sysdeps/unix/sysv/linux/microblaze/vfork.S
+index 9592cb4f28..b537f1ce34 100644
+--- a/sysdeps/unix/sysv/linux/microblaze/vfork.S
++++ b/sysdeps/unix/sysv/linux/microblaze/vfork.S
+@@ -40,6 +40,8 @@ ENTRY (__vfork)
+        nop
+ 
+ PSEUDO_END (__vfork)
+-libc_hidden_def (__vfork)
+ 
++#if IS_IN (libc)
+ weak_alias (__vfork, vfork)
++libc_hidden_def (__vfork)
++#endif
+-- 
+2.10.2
+
diff --git a/recipes-microblaze/glibc/glibc-initial_2.24.bbappend b/recipes-microblaze/glibc/glibc-initial_2.24.bbappend
new file mode 100644
index 00000000..a4beb0b8
--- /dev/null
+++ b/recipes-microblaze/glibc/glibc-initial_2.24.bbappend
@@ -0,0 +1,4 @@
+
+FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
+SRC_URI += "file://MicroBlaze-fix-up-pt-vfork-symbol-definitions.patch"
+
diff --git a/recipes-microblaze/glibc/glibc_2.24.bbappend b/recipes-microblaze/glibc/glibc_2.24.bbappend
new file mode 100644
index 00000000..a4beb0b8
--- /dev/null
+++ b/recipes-microblaze/glibc/glibc_2.24.bbappend
@@ -0,0 +1,4 @@
+
+FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
+SRC_URI += "file://MicroBlaze-fix-up-pt-vfork-symbol-definitions.patch"
+