elf: Do not run IFUNC resolvers for LD_DEBUG=unused [BZ #24214]

This commit adds missing skip_ifunc checks to aarch64, arm, i386,
sparc, and x86_64.  A new test case ensures that IRELATIVE IFUNC
resolvers do not run in various diagnostic modes of the dynamic
loader.

Reviewed-By: Szabolcs Nagy <szabolcs.nagy@arm.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/elf/tst-ifunc-fault-lazy.c b/elf/tst-ifunc-fault-lazy.c
new file mode 100644
index 0000000000..3389de273f
--- /dev/null
+++ b/elf/tst-ifunc-fault-lazy.c
@@ -0,0 +1,57 @@
+/* Program with local IFUNC resolver which crashes, for testing bug 24214.
+   Copyright (C) 2019 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
+   <https://www.gnu.org/licenses/>.  */
+
+/* The construct below is expected to produce an IRELATIVE relocation
+   with an IFUNC resolver that crashes. ldd should not performs such
+   relocations.  */
+
+#include <config.h>
+
+#ifdef HAVE_GCC_IFUNC
+
+# include <stddef.h>
+
+static void
+implementation (void)
+{
+  /* Produce a crash, without depending on any relocations.  */
+  volatile char *volatile p = NULL;
+  *p = 0;
+}
+
+static __typeof__ (implementation) *
+resolver (void)
+{
+  /* Produce a crash, without depending on any relocations.  */
+  volatile char *volatile p = NULL;
+  *p = 0;
+  return implementation;
+}
+
+static void magic (void) __attribute__ ((ifunc ("resolver")));
+
+void (*magic_ptr) (void) = magic;
+
+#endif /* HAVE_GCC_IFUNC */
+
+/* The program is expected not to run.  */
+int
+main (void)
+{
+  return 1;
+}