posix: Consolidate Linux pause syscall

This patch consolidates the pause Linux implementation on
sysdeps/unix/sysv/linux/pause.c.  If defined the pause syscall
(__NR_pause) will be used, other ppoll with 0 arguments will be
used instead.

It has the small advantage of generic pause implementation with
uses rt_sigprocmask plus rt_sigsuspend because it requires only
one syscall and the pause is done atomically regarding signal
handling (for instance, pause may not be interrupted if the
signal arrives between the rt_sigprocmask and rt_sigsuspend
syscall).

Checked on i686-linux-gnu, x86_64-linux-gnu, x86_64-linux-gnux32,
arch64-linux-gnu, arm-linux-gnueabihf, powerpc64le-linux-gnu,
sparc64-linux-gnu, and sparcv9-linux-gnu.

	* sysdeps/unix/sysv/linux/generic/pause.c: Remove file.
	* sysdeps/unix/sysv/linux/sparc/sparc64/pause.c: Likewise.
	* sysdeps/unix/sysv/linux/sparc/kernel-features.h [__arch64__]
	(__NR_pause): Undefine.
	* sysdeps/unix/sysv/linux/pause.c: New file.
	* sysdeps/unix/sysv/linux/syscalls.list: Remove pause from
	auto-generation list.

1 files changed, 35 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/pause.c b/sysdeps/unix/sysv/linux/pause.c
new file mode 100644
index 0000000000..4ccce9ebd8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/pause.c
@@ -0,0 +1,35 @@
+/* Linux pause syscall implementation.
+   Copyright (C) 2017 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/>.  */
+
+#include <signal.h>
+#include <unistd.h>
+#include <sysdep-cancel.h>
+
+/* Suspend the process until a signal arrives.
+   This always returns -1 and sets errno to EINTR.  */
+
+int
+__libc_pause (void)
+{
+#ifdef __NR_pause
+  return SYSCALL_CANCEL (pause);
+#else
+  return SYSCALL_CANCEL (ppoll, NULL, 0, NULL, NULL);
+#endif
+}
+weak_alias (__libc_pause, pause)