y2038: nptl: Convert pthread_cond_{clock|timed}wait to support 64 bit time

The pthread_cond_clockwait and pthread_cond_timedwait have been converted
to support 64 bit time.

This change introduces new futex_abstimed_wait_cancelable64 function in
./sysdeps/nptl/futex-helpers.c, which uses futex_time64 where possible
and tries to replace low-level preprocessor macros from
lowlevellock-futex.h
The pthread_cond_{clock|timed}wait only accepts absolute time. Moreover,
there is no need to check for NULL passed as *abstime pointer as
__pthread_cond_wait_common() always passes non-NULL struct __timespec64
pointer to futex_abstimed_wait_cancellable64().

For systems with __TIMESIZE != 64 && __WORDSIZE == 32:
- Conversions between 64 bit time to 32 bit are necessary
- Redirection to __pthread_cond_{clock|timed}wait64 will provide support
  for 64 bit time

The futex_abstimed_wait_cancelable64 function has been put into a separate
file on the purpose - to avoid issues apparent on the m68k architecture
related to small number of available registers (there is not enough
registers to put all necessary arguments in them if the above function
would be added to futex-internal.h with __always_inline attribute).

In fact - new function - namely __futex_abstimed_wait_cancellable32 is
used to reduce number of needed registers (as some in-register values are
stored on the stack when function call is made).

Build tests:
./src/scripts/build-many-glibcs.py glibcs

Run-time tests:
- Run specific tests on ARM/x86 32bit systems (qemu):
  https://github.com/lmajewski/meta-y2038 and run tests:
  https://github.com/lmajewski/y2038-tests/commits/master

Above tests were performed with Y2038 redirection applied as well as without
to test the proper usage of both __pthread_cond_{clock|timed}wait64 and
__pthread_cond_{clock|timed}wait.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

3 files changed, 106 insertions, 1 deletions

diff --git a/sysdeps/nptl/Makefile b/sysdeps/nptl/Makefile
index 0631a870c8..a65be3b7ea 100644
--- a/sysdeps/nptl/Makefile
+++ b/sysdeps/nptl/Makefile
@@ -17,7 +17,7 @@
 # <https://www.gnu.org/licenses/>.
 
 ifeq ($(subdir),nptl)
-libpthread-sysdep_routines += errno-loc
+libpthread-sysdep_routines += errno-loc futex-internal
 endif
 
 ifeq ($(subdir),rt)
diff --git a/sysdeps/nptl/futex-internal.c b/sysdeps/nptl/futex-internal.c
new file mode 100644
index 0000000000..5e52f17dee
--- /dev/null
+++ b/sysdeps/nptl/futex-internal.c
@@ -0,0 +1,95 @@
+/* futex helper functions for glibc-internal use.
+   Copyright (C) 2020 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <errno.h>
+#include <sysdep.h>
+#include <time.h>
+#include <futex-internal.h>
+#include <kernel-features.h>
+
+#ifndef __ASSUME_TIME64_SYSCALLS
+static int
+__futex_abstimed_wait_cancellable32 (unsigned int* futex_word,
+                                     unsigned int expected, clockid_t clockid,
+                                     const struct __timespec64* abstime,
+                                     int private)
+{
+  if (! in_time_t_range (abstime->tv_sec))
+    return -EOVERFLOW;
+
+  unsigned int clockbit = (clockid == CLOCK_REALTIME)
+	  ? FUTEX_CLOCK_REALTIME : 0;
+  int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
+
+  struct timespec ts32 = valid_timespec64_to_timespec (*abstime);
+  return INTERNAL_SYSCALL_CANCEL (futex, futex_word, op, expected,
+                                  &ts32, NULL /* Unused.  */,
+                                  FUTEX_BITSET_MATCH_ANY);
+}
+#endif
+
+int
+__futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
+                                    unsigned int expected, clockid_t clockid,
+                                    const struct __timespec64* abstime,
+                                    int private)
+{
+  unsigned int clockbit;
+  int err;
+
+  /* Work around the fact that the kernel rejects negative timeout values
+     despite them being valid.  */
+  if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
+    return ETIMEDOUT;
+
+  if (! lll_futex_supported_clockid (clockid))
+    return EINVAL;
+
+  clockbit = (clockid == CLOCK_REALTIME) ? FUTEX_CLOCK_REALTIME : 0;
+  int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
+
+  err = INTERNAL_SYSCALL_CANCEL (futex_time64, futex_word, op, expected,
+                                 abstime, NULL /* Unused.  */,
+                                 FUTEX_BITSET_MATCH_ANY);
+#ifndef __ASSUME_TIME64_SYSCALLS
+if (err == -ENOSYS)
+	err = __futex_abstimed_wait_cancellable32 (futex_word, expected,
+	                                           clockid, abstime, private);
+#endif
+
+  switch (err)
+    {
+    case 0:
+    case -EAGAIN:
+    case -EINTR:
+    case -ETIMEDOUT:
+    case -EOVERFLOW:  /* Passed absolute timeout uses 64 bit time_t type, but
+                         underlying kernel does not support 64 bit time_t futex
+                         syscalls.  */
+      return -err;
+
+    case -EFAULT: /* Must have been caused by a glibc or application bug.  */
+    case -EINVAL: /* Either due to wrong alignment or due to the timeout not
+		     being normalized.  Must have been caused by a glibc or
+		     application bug.  */
+    case -ENOSYS: /* Must have been caused by a glibc bug.  */
+    /* No other errors are documented at this time.  */
+    default:
+      futex_fatal_error ();
+    }
+}
diff --git a/sysdeps/nptl/futex-internal.h b/sysdeps/nptl/futex-internal.h
index 159aae82dc..84ab3f3853 100644
--- a/sysdeps/nptl/futex-internal.h
+++ b/sysdeps/nptl/futex-internal.h
@@ -519,4 +519,14 @@ futex_timed_wait_cancel64 (pid_t *tidp,  pid_t tid,
       futex_fatal_error ();
     }
 }
+
+/* The futex_abstimed_wait_cancelable64 has been moved to a separate file
+   to avoid problems with exhausting available registers on some architectures
+   - e.g. on m68k architecture.  */
+int
+__futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
+                                    unsigned int expected, clockid_t clockid,
+                                    const struct __timespec64* abstime,
+                                    int private) attribute_hidden;
+
 #endif  /* futex-internal.h */