linux: Add time64 pselect support

The syscall __NR_pselect6_time64 (32-bit) or __NR_pselect6 (64-bit)
is used as default.  For architectures with __ASSUME_TIME64_SYSCALLS
the 32-bit fallback uses __NR_pselec6.

To accomodate microblaze missing pselect6 support on kernel older
than 3.15 the fallback is moved to its own function to the microblaze
specific implementation can override it.

Checked on x86_64-linux-gnu and i686-linux-gnu (on 5.4 and on 4.15
kernel).

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/microblaze/pselect32.c b/sysdeps/unix/sysv/linux/microblaze/pselect32.c
new file mode 100644
index 0000000..fe9dac8
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/microblaze/pselect32.c
@@ -0,0 +1,61 @@
+/* Synchronous I/O multiplexing.  Linux/microblaze version.
+   Copyright (C) 2019-2020 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 <signal.h>
+#include <time.h>
+#include <sys/poll.h>
+#include <sysdep-cancel.h>
+
+#ifndef __ASSUME_PSELECT
+int
+__pselect32 (int nfds, fd_set *readfds, fd_set *writefds,
+	     fd_set *exceptfds, const struct __timespec64 *timeout,
+	     const sigset_t *sigmask)
+{
+  /* The fallback uses 'select' which shows the race condition regarding
+     signal mask set/restore, requires two additional syscalls, and has
+     a worse timeout precision (microseconds instead of nanoseconds).  */
+
+  struct timeval tv32, *ptv32 = NULL;
+  if (timeout != NULL)
+    {
+      if (! in_time_t_range (timeout->tv_sec)
+	  || ! valid_nanoseconds (timeout->tv_nsec))
+	{
+	  __set_errno (EINVAL);
+	  return -1;
+	}
+
+      tv32 = valid_timespec64_to_timeval (*timeout);
+      ptv32 = &tv32;
+    }
+
+  sigset_t savemask;
+  if (sigmask != NULL)
+    __sigprocmask (SIG_SETMASK, sigmask, &savemask);
+
+  /* select itself is a cancellation entrypoint.  */
+  int ret = __select (nfds, readfds, writefds, exceptfds, ptv32);
+
+  if (sigmask != NULL)
+    __sigprocmask (SIG_SETMASK, &savemask, NULL);
+
+  return ret;
+}
+#endif /* __ASSUME_PSELECT  */