nptl: Add C11 threads thrd_* functions

This patch adds the thrd_* definitions from C11 threads (ISO/IEC 9899:2011),
more specifically thrd_create, thrd_curent, rhd_detach, thrd_equal,
thrd_exit, thrd_join, thrd_sleep, thrd_yield, and required types.

Mostly of the definitions are composed based on POSIX conterparts, such as
thrd_t (using pthread_t).  For thrd_* function internally direct
POSIX pthread call are used with the exceptions:

  1. thrd_start uses pthread_create internal implementation, but changes
     how to actually calls the start routine.  This is due the difference
     in signature between POSIX and C11, where former return a 'void *'
     and latter 'int'.
     To avoid calling convention issues due 'void *' to int cast, routines
     from C11 threads are started slight different than default pthread one.
     Explicit cast to expected return are used internally on pthread_create
     and the result is stored back to void also with an explicit cast.

  2. thrd_sleep uses nanosleep internal direct syscall to avoid clobbering
     errno and to handle expected standard return codes.  It is a
     cancellation entrypoint to be consistent with both thrd_join and
     cnd_{timed}wait.

  3. thrd_yield also uses internal direct syscall to avoid errno clobbering.

Checked with a build for all major ABI (aarch64-linux-gnu, alpha-linux-gnu,
arm-linux-gnueabi, i386-linux-gnu, ia64-linux-gnu, m68k-linux-gnu,
microblaze-linux-gnu [1], mips{64}-linux-gnu, nios2-linux-gnu,
powerpc{64le}-linux-gnu, s390{x}-linux-gnu, sparc{64}-linux-gnu,
and x86_64-linux-gnu).

Also ran a full check on aarch64-linux-gnu, x86_64-linux-gnu, i686-linux-gnu,
arm-linux-gnueabhf, and powerpc64le-linux-gnu.

	[BZ #14092]
	* conform/Makefile (conformtest-headers-ISO11): Add threads.h.
	(linknamespace-libs-ISO11): Add libpthread.a.
	* conform/data/threads.h-data: New file: add C11 thrd_* types and
	functions.
	* include/stdc-predef.h (__STDC_NO_THREADS__): Remove definition.
	* nptl/Makefile (headers): Add threads.h.
	(libpthread-routines): Add new C11 thread thrd_create, thrd_current,
	thrd_detach, thrd_equal, thrd_exit, thrd_join, thrd_sleep, and
	thrd_yield.
	* nptl/Versions (libpthread) [GLIBC_2.28]): Add new C11 thread
	thrd_create, thrd_current, thrd_detach, thrd_equal, thrd_exit,
	thrd_join, thrd_sleep, and thrd_yield symbols.
	* nptl/descr.h (struct pthread): Add c11 field.
	* nptl/pthreadP.h (ATTR_C11_THREAD): New define.
	* nptl/pthread_create.c (START_THREAD_DEFN): Call C11 thread start
	routine with expected function prototype.
	(__pthread_create_2_1): Add C11 threads check based on attribute
	value.
	* sysdeps/unix/sysdep.h (INTERNAL_SYSCALL_CANCEL): New macro.
	* nptl/thrd_create.c: New file.
	* nptl/thrd_current.c: Likewise.
	* nptl/thrd_detach.c: Likewise.
	* nptl/thrd_equal.c: Likewise.
	* nptl/thrd_exit.c: Likewise.
	* nptl/thrd_join.c: Likewise.
	* nptl/thrd_priv.h: Likewise.
	* nptl/thrd_sleep.c: Likewise.
	* nptl/thrd_yield.c: Likewise.
	* include/threads.h: Likewise.

1 files changed, 90 insertions, 0 deletions

diff --git a/nptl/threads.h b/nptl/threads.h
new file mode 100644
index 0000000000..5258e23919
--- /dev/null
+++ b/nptl/threads.h
@@ -0,0 +1,90 @@
+/* ISO C11 Standard: 7.26 - Thread support library  <threads.h>.
+   Copyright (C) 2018 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/>.  */
+
+#ifndef _THREADS_H
+#define _THREADS_H	1
+
+#include <features.h>
+#include <time.h>
+
+__BEGIN_DECLS
+
+#include <bits/types/struct_timespec.h>
+
+typedef unsigned long int thrd_t;
+typedef int (*thrd_start_t) (void*);
+
+/* Exit and error codes.  */
+enum
+{
+  thrd_success  = 0,
+  thrd_busy     = 1,
+  thrd_error    = 2,
+  thrd_nomem    = 3,
+  thrd_timedout = 4
+};
+
+/* Threads functions.  */
+
+/* Create a new thread executing the function __FUNC.  Arguments for __FUNC
+   are passed through __ARG.  If succesful, __THR is set to new thread
+   identifier.  */
+extern int thrd_create (thrd_t *__thr, thrd_start_t __func, void *__arg);
+
+/* Check if __LHS and __RHS point to the same thread.  */
+extern int thrd_equal (thrd_t __lhs, thrd_t __rhs);
+
+/* Return current thread identifier.  */
+extern thrd_t thrd_current (void);
+
+/* Block current thread execution for at least the time pointed by
+   __TIME_POINT.  The current thread may resume if receives a signal.  In
+   that case, if __REMAINING is not NULL, the remaining time is stored in
+   the object pointed by it.  */
+extern int thrd_sleep (const struct timespec *__time_point,
+		       struct timespec *__remaining);
+
+/* Terminate current thread execution, cleaning up any thread local
+   storage and freeing resources.  Returns the value specified in __RES.  */
+extern void thrd_exit (int __res) __attribute__ ((__noreturn__));
+
+/* Detach the thread identified by __THR from the current environment
+   (it does not allow join or wait for it).  */
+extern int thrd_detach (thrd_t __thr);
+
+/* Block current thread until execution of __THR is complete.  In case that
+   __RES is not NULL, will store the return value of __THR when exiting.  */
+extern int thrd_join (thrd_t __thr, int *__res);
+
+/* Stop current thread execution and call the scheduler to decide which
+   thread should execute next.  The current thread may be selected by the
+   scheduler to keep running.  */
+extern void thrd_yield (void);
+
+#ifdef __USE_EXTERN_INLINES
+/* Optimizations.  */
+__extern_inline int
+thrd_equal (thrd_t __thread1, thrd_t __thread2)
+{
+  return __thread1 == __thread2;
+}
+#endif
+
+__END_DECLS
+
+#endif /* _THREADS_H */