Retain libc.so.6 debuglink section, remove ld.so debuginfo file (#2090744)

This commit fixes wrap-find-debuginfo.sh so that:
* the .gnu_debuglink section of libc.so.6 is retained, and
* the redundant debuginfo file generated for ld.so is removed

Co-Authored-By: Benjamin Herrenschmidt <benh@amazon.com>
Reviewed-by: Florian Weimer <fweimer@redhat.com>

Rawhide commit: 8e2d77f734

glibc.spec

@@ -152,7 +152,7 @@ end \
 Summary: The GNU libc libraries
 Name: glibc
 Version: %{glibcversion}
-Release: 16%{?dist}
+Release: 17%{?dist}
 
 # In general, GPLv2+ is used by programs, LGPLv2+ is used for
 # libraries.
@@ -2171,6 +2171,11 @@ update_gconv_modules_cache ()
 %files -f compat-libpthread-nonshared.filelist -n compat-libpthread-nonshared
 
 %changelog
+* Tue Sep 06 2022 Arjun Shankar <arjun@redhat.com> - 2.35-17
+- Co-Authored-By: Benjamin Herrenschmidt <benh@amazon.com>
+- Retain .gnu_debuglink section in libc.so.6 (#2090744)
+- Remove redundant ld.so debuginfo file (#2090744)
+
 * Tue Aug 23 2022 Arjun Shankar <arjun@redhat.com> - 2.35-16
 - Auto-sync with upstream branch release/2.35/master,
   commit 83f1d9851e0b143991448d41ff50744d9972cb6e:

wrap-find-debuginfo.sh

@@ -17,6 +17,7 @@ set -ex
 
 ldso_tmp="$(mktemp)"
 libc_tmp="$(mktemp)"
+libc_dlink_tmp="$(mktemp)"
 
 # Prefer a separately installed debugedit over the RPM-integrated one.
 if command -v debugedit >/dev/null ; then
@@ -26,7 +27,7 @@ else
 fi
 
 cleanup () {
-    rm -f "$ldso_tmp" "$libc_tmp"
+    rm -f "$ldso_tmp" "$libc_tmp" "$libc_dlink_tmp"
 }
 trap cleanup 0
 
@@ -66,6 +67,10 @@ cp "$libc_path" "$libc_tmp"
 # Run the debuginfo extraction.
 "$script_path" "$@"
 
+# libc.so.6: Extract the .gnu_debuglink section
+objcopy -j.gnu_debuglink --set-section-flags .gnu_debuglink=alloc \
+  -O binary "$libc_path" "$libc_dlink_tmp"
+
 # Restore the original files.
 cp "$ldso_tmp" "$ldso_path"
 cp "$libc_tmp" "$libc_path"
@@ -74,6 +79,23 @@ cp "$libc_tmp" "$libc_path"
 objcopy --merge-notes "$ldso_path"
 objcopy --merge-notes "$libc_path"
 
+# libc.so.6: Restore the .gnu_debuglink section
+objcopy --add-section .gnu_debuglink="$libc_dlink_tmp" "$libc_path"
+
+# ld.so does not have separated debuginfo and so the debuginfo file
+# generated by find-debuginfo is redundant.  Therefore, remove it.
+ldso_debug=
+for ldso_debug_candidate in `find "$sysroot_path" -regextype posix-extended \
+  -regex '.*/ld(-.*|64|)\.so\.[0-9]+.*debug$' -type f` ; do
+    if test -z "$ldso_debug" ; then
+	ldso_debug="$ldso_debug_candidate"
+    else
+	echo "error: multiple ld.so debug candidates: $ldso_debug, $ldso_debug_candidate"
+	exit 1
+    fi
+done
+rm -f "$ldso_debug"
+
 # libc.so.6: Reduce to valuable symbols.  Eliminate file symbols,
 # annobin symbols, and symbols used by the glibc build to implement
 # hidden aliases (__EI_*).  We would also like to remove __GI_*