detect broken linker handling of __ehdr_start

Older versions of ld on ia64 support __ehdr_start, but generate relocs
when they shouldn't.  This causes the ld.so to not run because it tries
to resolve the __ehdr_start symbol (but it's not exported).

1 files changed, 18 insertions, 5 deletions

diff --git a/configure.ac b/configure.ac
index e89faa0dfe..255339983a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1880,7 +1880,10 @@ if test $libc_cv_predef_stack_protector = yes; then
 fi
 libc_extra_cppflags=
 
-AC_CACHE_CHECK([whether the linker provides __ehdr_start],
+# Some linkers on some architectures support __ehdr_start but with
+# bugs.  Make sure usage of it does not create relocations in the
+# output (as the linker should resolve them all for us).
+AC_CACHE_CHECK([whether the linker provides working __ehdr_start],
 	       libc_cv_ehdr_start, [
 old_CFLAGS="$CFLAGS"
 old_LDFLAGS="$LDFLAGS"
@@ -1889,16 +1892,26 @@ CFLAGS="$CFLAGS -fPIC"
 LDFLAGS="$LDFLAGS -nostdlib -nostartfiles -shared"
 LIBS=
 AC_LINK_IFELSE([AC_LANG_SOURCE([
-extern const char __ehdr_start __attribute__ ((visibility ("hidden")));
-const char *ehdr (void) { return &__ehdr_start; }
+typedef struct {
+  char foo;
+  long val;
+} Ehdr;
+extern const Ehdr __ehdr_start __attribute__ ((visibility ("hidden")));
+long ehdr (void) { return __ehdr_start.val; }
 ])],
-	       [libc_cv_ehdr_start=yes], [libc_cv_ehdr_start=no])
+	       [if $READELF -r conftest | fgrep __ehdr_start >/dev/null; then
+		  libc_cv_ehdr_start=broken
+		else
+		  libc_cv_ehdr_start=yes
+		fi], [libc_cv_ehdr_start=no])
 CFLAGS="$old_CFLAGS"
 LDFLAGS="$old_LDFLAGS"
 LIBS="$old_LIBS"
 ])
-if test $libc_cv_ehdr_start = yes; then
+if test "$libc_cv_ehdr_start" = yes; then
   AC_DEFINE([HAVE_EHDR_START])
+elif test "$libc_cv_ehdr_start" = broken; then
+  AC_MSG_WARN([linker is broken -- you should upgrade])
 fi
 
 AC_CACHE_CHECK(for __builtin_trap with no external dependencies,