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, 16 insertions, 2 deletions

diff --git a/nptl/pthread_create.c b/nptl/pthread_create.c
index 5f5a007..fe75d04 100644
--- a/nptl/pthread_create.c
+++ b/nptl/pthread_create.c
@@ -472,7 +472,19 @@ START_THREAD_DEFN
       LIBC_PROBE (pthread_start, 3, (pthread_t) pd, pd->start_routine, pd->arg);
 
       /* Run the code the user provided.  */
-      THREAD_SETMEM (pd, result, pd->start_routine (pd->arg));
+      void *ret;
+      if (pd->c11)
+	{
+	  /* The function pointer of the c11 thread start is cast to an incorrect
+	     type on __pthread_create_2_1 call, however it is casted back to correct
+	     one so the call behavior is well-defined (it is assumed that pointers
+	     to void are able to represent all values of int.  */
+	  int (*start)(void*) = (int (*) (void*)) pd->start_routine;
+	  ret = (void*) (uintptr_t) start (pd->arg);
+	}
+      else
+	ret = pd->start_routine (pd->arg);
+      THREAD_SETMEM (pd, result, ret);
     }
 
   /* Call destructors for the thread_local TLS variables.  */
@@ -625,7 +637,8 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
   const struct pthread_attr *iattr = (struct pthread_attr *) attr;
   struct pthread_attr default_attr;
   bool free_cpuset = false;
-  if (iattr == NULL)
+  bool c11 = (attr == ATTR_C11_THREAD);
+  if (iattr == NULL || c11)
     {
       lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
       default_attr = __default_pthread_attr;
@@ -683,6 +696,7 @@ __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
      get the information from its thread descriptor.  */
   pd->start_routine = start_routine;
   pd->arg = arg;
+  pd->c11 = c11;
 
   /* Copy the thread attribute flags.  */
   struct pthread *self = THREAD_SELF;