elf: Add tests with a local IFUNC resolver [BZ #23937]

The existing tests all use global symbols (but with different
visibility).  Local symbols could be treated differently by the
compiler and linker (as was the case on POWER ELFv2, causing
bug 23937), and we did not have test coverage for this.

Tested on x86-64 and POWER ELFv2 little-endian, with and without
--disable-multi-arch.  On POWER, the test cases elf/ifuncmain9,
elf/ifuncmain9pic, elf/ifuncmain9pie reproduce bug 23937 with older
binutils.

1 files changed, 107 insertions, 0 deletions

diff --git a/elf/ifuncmain9.c b/elf/ifuncmain9.c
new file mode 100644
index 0000000..a8a9c49
--- /dev/null
+++ b/elf/ifuncmain9.c
@@ -0,0 +1,107 @@
+/* Test for IFUNC handling with local definitions.
+   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
+   <http://www.gnu.org/licenses/>.  */
+
+/* This test is based on gcc.dg/attr-ifunc-4.c.  */
+
+#include <config.h>
+
+#ifdef HAVE_GCC_IFUNC
+
+# include <stdbool.h>
+# include <stdio.h>
+
+/* Do not use the test framework, so that the process setup is not
+   disturbed.  */
+
+static volatile int implementation_called;
+static volatile int resolver_called;
+
+/* Just a random constant, to check that we called the right
+   function.  */
+enum { random_constant = 0x3a88d66d };
+
+static int
+implementation (void)
+{
+  ++implementation_called;
+  return random_constant;
+}
+
+static __typeof__ (implementation) *
+resolver (void)
+{
+  ++resolver_called;
+  return implementation;
+}
+
+static int magic (void) __attribute__ ((ifunc ("resolver")));
+
+int
+main (void)
+{
+  bool errors = false;
+
+  if (implementation_called != 0)
+    {
+      printf ("error: initial value of implementation_called is not zero:"
+              " %d\n", implementation_called);
+      errors = true;
+    }
+
+  /* This can be zero if the reference is bound lazily.  */
+  printf ("info: initial value of resolver_called: %d\n", resolver_called);
+
+  int magic_value = magic ();
+  if (magic_value != random_constant)
+    {
+      printf ("error: invalid magic value: 0x%x\n", magic_value);
+      errors = true;
+    }
+
+  printf ("info: resolver_called value: %d\n", resolver_called);
+  if (resolver_called == 0)
+    {
+      /* In theory, the resolver could be called multiple times if
+         several relocations are needed.  */
+      puts ("error: invalid resolver_called value (must not be zero)");
+      errors = true;
+    }
+
+  printf ("info: implementation_called value: %d\n", implementation_called);
+  if (implementation_called != 1)
+    {
+      puts ("error: invalid implementation_called value (must be 1)");
+      errors = true;
+    }
+
+  return errors;
+}
+
+#else  /* !HAVE_GCC_IFUNC */
+
+# include <support/check.h>
+
+static int
+do_test (void)
+{
+  FAIL_UNSUPPORTED ("GCC does not support the ifunc attribute");
+  return 1;                     /* Not reachable.  */
+}
+
+# include <support/test-driver.c>
+#endif