Downstream adjustment: Change return type of
rseq_register_current_thread to bool.  Upstream, this was part of the
commit that introduced the ABI symbols.

commit a41c8e92350e744a4bc639df5025153d05263e7f
Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu Dec 9 09:49:32 2021 +0100

    nptl: rseq failure after registration on main thread is fatal

    This simplifies the application programming model.

    Browser sandboxes have already been fixed:

      Sandbox is incompatible with rseq registration
      <https://bugzilla.mozilla.org/show_bug.cgi?id=1651701>

      Allow rseq in the Linux sandboxes. r=gcp
      <https://hg.mozilla.org/mozilla-central/rev/042425712eb1>

      Sandbox needs to support rseq system call
      <https://bugs.chromium.org/p/chromium/issues/detail?id=1104160>

      Linux sandbox: Allow rseq(2)
      <https://chromium.googlesource.com/chromium/src.git/+/230675d9ac8f1>

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

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index f405fa356c2955ce..109c5e3dc78c9aa2 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -371,7 +371,8 @@ start_thread (void *arg)
   /* Register rseq TLS to the kernel.  */
   {
     bool do_rseq = THREAD_GETMEM (pd, flags) & ATTR_FLAG_DO_RSEQ;
-    rseq_register_current_thread (pd, do_rseq);
+    if (!rseq_register_current_thread (pd, do_rseq) && do_rseq)
+      __libc_fatal ("Fatal glibc error: rseq registration failed\n");
   }
 
 #ifndef __ASSUME_SET_ROBUST_LIST
diff --git a/sysdeps/unix/sysv/linux/rseq-internal.h b/sysdeps/unix/sysv/linux/rseq-internal.h
index 15bc7ffd6eda632d..6a3441f2cc49e7c4 100644
--- a/sysdeps/unix/sysv/linux/rseq-internal.h
+++ b/sysdeps/unix/sysv/linux/rseq-internal.h
@@ -26,7 +26,7 @@
 #include <sys/rseq.h>
 
 #ifdef RSEQ_SIG
-static inline void
+static inline bool
 rseq_register_current_thread (struct pthread *self, bool do_rseq)
 {
   if (do_rseq)
@@ -35,15 +35,17 @@ rseq_register_current_thread (struct pthread *self, bool do_rseq)
                                        sizeof (self->rseq_area),
                                        0, RSEQ_SIG);
       if (!INTERNAL_SYSCALL_ERROR_P (ret))
-        return;
+        return true;
     }
   THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
+  return false;
 }
 #else /* RSEQ_SIG */
 static inline void
 rseq_register_current_thread (struct pthread *self, bool do_rseq)
 {
   THREAD_SETMEM (self, rseq_area.cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
+  return false;
 }
 #endif /* RSEQ_SIG */