nptl: Add rseq registration

The rseq area is placed directly into struct pthread.  rseq
registration failure is not treated as an error, so it is possible
that threads run with inconsistent registration status.

<sys/rseq.h> is not yet installed as a public header.

Co-Authored-By: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

1 files changed, 260 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/tst-rseq-nptl.c b/sysdeps/unix/sysv/linux/tst-rseq-nptl.c
new file mode 100644
index 0000000000..d31d94445c
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/tst-rseq-nptl.c
@@ -0,0 +1,260 @@
+/* Restartable Sequences NPTL test.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+
+   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/>.  */
+
+/* These tests validate that rseq is registered from various execution
+   contexts (main thread, destructor, other threads, other threads created
+   from destructor, forked process (without exec), pthread_atfork handlers,
+   pthread setspecific destructors, signal handlers, atexit handlers).
+
+   See the Linux kernel selftests for extensive rseq stress-tests.  */
+
+#include <stdio.h>
+#include <support/check.h>
+#include <support/xthread.h>
+#include <sys/rseq.h>
+#include <unistd.h>
+
+#ifdef RSEQ_SIG
+# include <array_length.h>
+# include <errno.h>
+# include <error.h>
+# include <pthread.h>
+# include <signal.h>
+# include <stdlib.h>
+# include <string.h>
+# include <support/namespace.h>
+# include <support/xsignal.h>
+# include <syscall.h>
+# include <sys/types.h>
+# include <sys/wait.h>
+# include "tst-rseq.h"
+
+static pthread_key_t rseq_test_key;
+
+static void
+atfork_prepare (void)
+{
+  if (!rseq_thread_registered ())
+    {
+      printf ("error: rseq not registered in pthread atfork prepare\n");
+      support_record_failure ();
+    }
+}
+
+static void
+atfork_parent (void)
+{
+  if (!rseq_thread_registered ())
+    {
+      printf ("error: rseq not registered in pthread atfork parent\n");
+      support_record_failure ();
+    }
+}
+
+static void
+atfork_child (void)
+{
+  if (!rseq_thread_registered ())
+    {
+      printf ("error: rseq not registered in pthread atfork child\n");
+      support_record_failure ();
+    }
+}
+
+static void
+rseq_key_destructor (void *arg)
+{
+  /* Cannot use deferred failure reporting after main returns.  */
+  if (!rseq_thread_registered ())
+    FAIL_EXIT1 ("rseq not registered in pthread key destructor");
+}
+
+static void
+atexit_handler (void)
+{
+  /* Cannot use deferred failure reporting after main returns.  */
+  if (!rseq_thread_registered ())
+    FAIL_EXIT1 ("rseq not registered in atexit handler");
+}
+
+/* Used to avoid -Werror=stringop-overread warning with
+   pthread_setspecific and GCC 11.  */
+static char one = 1;
+
+static void
+do_rseq_main_test (void)
+{
+  TEST_COMPARE (atexit (atexit_handler), 0);
+  rseq_test_key = xpthread_key_create (rseq_key_destructor);
+  TEST_COMPARE (pthread_atfork (atfork_prepare, atfork_parent, atfork_child), 0);
+  xraise (SIGUSR1);
+  TEST_COMPARE (pthread_setspecific (rseq_test_key, &one), 0);
+  TEST_VERIFY_EXIT (rseq_thread_registered ());
+}
+
+static void
+cancel_routine (void *arg)
+{
+  if (!rseq_thread_registered ())
+    {
+      printf ("error: rseq not registered in cancel routine\n");
+      support_record_failure ();
+    }
+}
+
+static pthread_barrier_t cancel_thread_barrier;
+static pthread_cond_t cancel_thread_cond = PTHREAD_COND_INITIALIZER;
+static pthread_mutex_t cancel_thread_mutex = PTHREAD_MUTEX_INITIALIZER;
+
+static void
+test_cancel_thread (void)
+{
+  pthread_cleanup_push (cancel_routine, NULL);
+  (void) xpthread_barrier_wait (&cancel_thread_barrier);
+  /* Wait forever until cancellation.  */
+  xpthread_cond_wait (&cancel_thread_cond, &cancel_thread_mutex);
+  pthread_cleanup_pop (0);
+}
+
+static void *
+thread_function (void * arg)
+{
+  int i = (int) (intptr_t) arg;
+
+  xraise (SIGUSR1);
+  if (i == 0)
+    test_cancel_thread ();
+  TEST_COMPARE (pthread_setspecific (rseq_test_key, &one), 0);
+  return rseq_thread_registered () ? NULL : (void *) 1l;
+}
+
+static void
+sighandler (int sig)
+{
+  if (!rseq_thread_registered ())
+    {
+      printf ("error: rseq not registered in signal handler\n");
+      support_record_failure ();
+    }
+}
+
+static void
+setup_signals (void)
+{
+  struct sigaction sa;
+
+  sigemptyset (&sa.sa_mask);
+  sigaddset (&sa.sa_mask, SIGUSR1);
+  sa.sa_flags = 0;
+  sa.sa_handler = sighandler;
+  xsigaction (SIGUSR1, &sa, NULL);
+}
+
+static int
+do_rseq_threads_test (int nr_threads)
+{
+  pthread_t th[nr_threads];
+  int i;
+  int result = 0;
+
+  xpthread_barrier_init (&cancel_thread_barrier, NULL, 2);
+
+  for (i = 0; i < nr_threads; ++i)
+    th[i] = xpthread_create (NULL, thread_function,
+                             (void *) (intptr_t) i);
+
+  (void) xpthread_barrier_wait (&cancel_thread_barrier);
+
+  xpthread_cancel (th[0]);
+
+  for (i = 0; i < nr_threads; ++i)
+    {
+      void *v;
+
+      v = xpthread_join (th[i]);
+      if (i != 0 && v != NULL)
+        {
+          printf ("error: join %d successful, but child failed\n", i);
+          result = 1;
+        }
+      else if (i == 0 && v == NULL)
+        {
+          printf ("error: join %d successful, child did not fail as expected\n", i);
+          result = 1;
+        }
+    }
+
+  xpthread_barrier_destroy (&cancel_thread_barrier);
+
+  return result;
+}
+
+static void
+subprocess_callback (void *closure)
+{
+  do_rseq_main_test ();
+}
+
+static void
+do_rseq_fork_test (void)
+{
+  support_isolate_in_subprocess (subprocess_callback, NULL);
+}
+
+static int
+do_rseq_test (void)
+{
+  int t[] = { 1, 2, 6, 5, 4, 3, 50 };
+  int i, result = 0;
+
+  if (!rseq_available ())
+    FAIL_UNSUPPORTED ("kernel does not support rseq, skipping test");
+  setup_signals ();
+  xraise (SIGUSR1);
+  do_rseq_main_test ();
+  for (i = 0; i < array_length (t); i++)
+    if (do_rseq_threads_test (t[i]))
+      result = 1;
+  do_rseq_fork_test ();
+  return result;
+}
+
+static void __attribute__ ((destructor))
+do_rseq_destructor_test (void)
+{
+  /* Cannot use deferred failure reporting after main returns.  */
+  if (do_rseq_test ())
+    FAIL_EXIT1 ("rseq not registered within destructor");
+  xpthread_key_delete (rseq_test_key);
+}
+
+#else /* RSEQ_SIG */
+static int
+do_rseq_test (void)
+{
+  FAIL_UNSUPPORTED ("glibc does not define RSEQ_SIG, skipping test");
+  return 0;
+}
+#endif /* RSEQ_SIG */
+
+static int
+do_test (void)
+{
+  return do_rseq_test ();
+}
+
+#include <support/test-driver.c>