[glibc] powerpc64le: guarantee a .gnu.attributes section [BZ #26220]

[glibc] powerpc64le: guarantee a .gnu.attributes section [BZ #26220]

[Paul E. Murphy]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c79607a474439d50e9f0bcae59709817112900cc

commit c79607a474439d50e9f0bcae59709817112900cc
Author: Paul E. Murphy <murphyp@linux.vnet.ibm.com>
Date:   Wed Jul 8 16:49:34 2020 -0500

    powerpc64le: guarantee a .gnu.attributes section [BZ #26220]
    
    Upstream GCC 11 development is now building the ibm128 runtime
    support (in libgcc) without a .gnu.attributes section on ppc64le.
    Ensure we have one to replace by building one ibm128 file in
    libc and libm with attributes.
    
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>
    Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>

Diff:
---
 sysdeps/powerpc/powerpc64/le/Makefile | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sysdeps/powerpc/powerpc64/le/Makefile b/sysdeps/powerpc/powerpc64/le/Makefile
index 05ab13d85c..033dc77b01 100644
--- a/sysdeps/powerpc/powerpc64/le/Makefile
+++ b/sysdeps/powerpc/powerpc64/le/Makefile
@@ -38,6 +38,14 @@ if [ ! -z "$(filter libm.so libc.so,$(notdir $1))" ]; then \
 fi
 endef
 
+# Ensure a .gnu.attributes section is present by building an ibm128 file with
+# -mgnu-attribute in both libm and libc shared libraries.  Prior to GCC 11 this
+# section was implicitly included via static libgcc ibm128 routines.
+ifeq ($(subdir),math)
+$(objpfx)m_ldexpl.os: CFLAGS += -mgnu-attribute
+$(objpfx)s_ldexpl.os: CFLAGS += -mgnu-attribute
+endif
+
 endif # ifeq ($(build-shared),yes)
 endif # ifeq ($(ibm128-fcts),yes)