Add a test of TLS support that will fail if leaky

nptl/Makefile

@@ -374,7 +374,7 @@ tests += tst-cancelx2 tst-cancelx3 tst-cancelx4 tst-cancelx5 \
 	 tst-oncex3 tst-oncex4
 ifeq ($(build-shared),yes)
 tests += tst-atfork2 tst-tls4 tst-_res1 tst-fini1 tst-compat-forwarder
-tests += tst-tls7a
+tests += tst-tls7a tst-tls7leak
 tests-internal += tst-tls3 tst-tls3-malloc tst-tls5 tst-stackguard1
 tests-nolibpthread += tst-fini1
 ifeq ($(have-z-execstack),yes)
@@ -390,7 +390,7 @@ modules-names = tst-atfork2mod tst-tls3mod tst-tls4moda tst-tls4modb \
 		tst-tls5modd tst-tls5mode tst-tls5modf tst-stack4mod \
 		tst-_res1mod1 tst-_res1mod2 tst-fini1mod \
 		tst-join7mod tst-compat-forwarder-mod
-modules-names += tst-tls7amod
+modules-names += tst-tls7amod tst-tls7leakmod
 ifneq ($(with-clang),yes)
 modules-names += tst-execstack-mod
 endif
@@ -409,6 +409,7 @@ tst-tls5modd.so-no-z-defs = yes
 tst-tls5mode.so-no-z-defs = yes
 tst-tls5modf.so-no-z-defs = yes
 tst-tls7amod.so-no-z-defs = yes
+tst-tls7leakmod.so-no-z-defs = yes
 
 ifeq ($(build-shared),yes)
 # Build all the modules even when not actually running test programs.
@@ -607,6 +608,10 @@ $(objpfx)tst-tls7a: $(libdl) $(shared-thread-library)
 $(objpfx)tst-tls7a.out: $(objpfx)tst-tls7amod.so
 $(objpfx)tst-tls7amod.so: $(shared-thread-library)
 
+$(objpfx)tst-tls7leak: $(libdl) $(shared-thread-library)
+$(objpfx)tst-tls7leak.out: $(objpfx)tst-tls7leakmod.so
+$(objpfx)tst-tls7leakmod.so: $(shared-thread-library)
+
 ifeq ($(build-shared),yes)
 $(objpfx)tst-tls6.out: tst-tls6.sh $(objpfx)tst-tls5 \
 		       $(objpfx)tst-tls5moda.so $(objpfx)tst-tls5modb.so \

nptl/tst-tls7leak.c

@@ -0,0 +1,117 @@
+/* Copyright (C) 2020 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 checks that leakage does not happen from repeated loads
+   of a module with TLS.  */
+
+#include <dlfcn.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+int (*tlsmod_fun) (void);
+
+/* Async-signal-safe TLS space is gotten via custom allocator using mmap(), so
+   it doesn't work to use functions like mtrace() or mallinfo().  */
+
+size_t get_vm_size (void)
+{
+  long result;
+  FILE *f = fopen ("/proc/self/statm", "r");
+
+  if (!f)
+    {
+      fprintf (stderr, "get_vm_size could not open /proc/self/statm\n");
+      return 0;
+    }
+  if (fscanf (f, "%lu", &result) != 1)
+    {
+      fprintf (stderr, "get_vm_size failed to read size\n");
+      return 0;
+    }
+  if (fclose (f) != 0)
+    {
+      fprintf (stderr, "get_vm_size fclose failed\n");
+      return 0;
+    }
+
+  return (size_t) result;
+}
+
+int
+do_test (void)
+{
+  int count = 0;
+
+  size_t start_size = get_vm_size ();
+
+  if (start_size == 0)
+    {
+      puts ("Cannot get vm size, test cannot run");
+      exit (0);
+    }
+
+  /* Open, use, and close a shared library repeatedly.  */
+  for (int i = 0; i < 1000; ++i)
+    {
+      void *h = dlopen ("tst-tls7leakmod.so", RTLD_NOW);
+      if (h == NULL)
+        {
+          puts ("dlopen failed");
+          exit (1);
+        }
+
+      tlsmod_fun = dlsym (h, "module_fun");
+      if (tlsmod_fun == NULL)
+        {
+          puts ("dlsym for module_fun failed");
+          exit (1);
+        }
+
+      count += tlsmod_fun ();
+
+      /* Don't leave dangling pointer after dlclose.  */
+      tlsmod_fun = NULL;
+
+      if (dlclose (h))
+        {
+          puts ("dlclose failed");
+          exit (1);
+        }
+
+    }
+
+  size_t end_size = get_vm_size ();
+  printf ("VM usage went from %ld to %ld pages", start_size, end_size);
+
+  /* Allow for some growth in usage.  */
+  if ((end_size - start_size) > 10)
+    {
+      printf (", which indicates a leak in TLS allocation\n");
+      return 1;
+    }
+  else
+    {
+      printf (", which is acceptable\n");
+      return 0;
+    }
+}
+
+#define TIMEOUT 8
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"

nptl/tst-tls7leakmod.c

@@ -0,0 +1,27 @@
+/* Copyright (C) 2020 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/>.  */
+
+/* Dynamic module that does not need to do much.  */
+
+__thread int avar;
+
+int
+module_fun (void)
+{
+  ++avar;
+  return avar;
+}