Index: head/lib/libc/sys/shm_open.c
===================================================================
--- head/lib/libc/sys/shm_open.c	(revision 359864)
+++ head/lib/libc/sys/shm_open.c	(revision 359865)
@@ -1,107 +1,93 @@
 /*
  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
  *
  * Copyright (c) 2019 Kyle Evans <kevans@FreeBSD.org>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice(s), this list of conditions and the following disclaimer as
  *    the first lines of this file unmodified other than the possible
  *    addition of one or more copyright notices.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice(s), this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
  * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
  * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
  * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <sys/mman.h>
-#include <sys/syscall.h>
 
 #include <errno.h>
 #include <fcntl.h>
 #include <limits.h>
-#include <unistd.h>
 #include <stdio.h>
 #include <string.h>
 
 #include "libc_private.h"
 
 __weak_reference(shm_open, _shm_open);
 __weak_reference(shm_open, __sys_shm_open);
 
-#define	SHM_OPEN2_OSREL		1300048
-
 #define	MEMFD_NAME_PREFIX	"memfd:"
 
 int
 shm_open(const char *path, int flags, mode_t mode)
 {
 
-	if (__getosreldate() >= SHM_OPEN2_OSREL)
-		return (__sys_shm_open2(path, flags | O_CLOEXEC, mode, 0,
-		    NULL));
-
-	/*
-	 * Fallback to shm_open(2) on older kernels.  The kernel will enforce
-	 * O_CLOEXEC in this interface, unlike the newer shm_open2 which does
-	 * not enforce it.  The newer interface allows memfd_create(), for
-	 * instance, to not have CLOEXEC on the returned fd.
-	 */
-	return (syscall(SYS_freebsd12_shm_open, path, flags, mode));
+	return (__sys_shm_open2(path, flags | O_CLOEXEC, mode, 0, NULL));
 }
 
 /*
  * The path argument is passed to the kernel, but the kernel doesn't currently
  * do anything with it.  Linux exposes it in linprocfs for debugging purposes
  * only, but our kernel currently will not do the same.
  */
 int
 memfd_create(const char *name, unsigned int flags)
 {
 	char memfd_name[NAME_MAX + 1];
 	size_t namelen;
 	int oflags, shmflags;
 
 	if (name == NULL)
 		return (EBADF);
 	namelen = strlen(name);
 	if (namelen + sizeof(MEMFD_NAME_PREFIX) - 1 > NAME_MAX)
 		return (EINVAL);
 	if ((flags & ~(MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB |
 	    MFD_HUGE_MASK)) != 0)
 		return (EINVAL);
 	/* Size specified but no HUGETLB. */
 	if ((flags & MFD_HUGE_MASK) != 0 && (flags & MFD_HUGETLB) == 0)
 		return (EINVAL);
 	/* We don't actually support HUGETLB. */
 	if ((flags & MFD_HUGETLB) != 0)
 		return (ENOSYS);
 
 	/* We've already validated that we're sufficiently sized. */
 	snprintf(memfd_name, NAME_MAX + 1, "%s%s", MEMFD_NAME_PREFIX, name);
 	oflags = O_RDWR;
 	shmflags = 0;
 	if ((flags & MFD_CLOEXEC) != 0)
 		oflags |= O_CLOEXEC;
 	if ((flags & MFD_ALLOW_SEALING) != 0)
 		shmflags |= SHM_ALLOW_SEALING;
 	return (__sys_shm_open2(SHM_ANON, oflags, 0, shmflags, memfd_name));
 }