Add a syscall test for [BZ #25810]

Add a test to pass 64-bit long arguments to syscall with undefined upper
32 bits on x32.

Tested on i386, x86-64 and x32 as well as with build-many-glibcs.py.

misc/Makefile

@@ -87,7 +87,7 @@ tests := tst-dirname tst-tsearch tst-fdset tst-mntent tst-hsearch \
 	 tst-preadvwritev tst-preadvwritev64 tst-makedev tst-empty \
 	 tst-preadvwritev2 tst-preadvwritev64v2 tst-warn-wide \
 	 tst-ldbl-warn tst-ldbl-error tst-dbl-efgcvt tst-ldbl-efgcvt \
-	 tst-mntent-autofs
+	 tst-mntent-autofs tst-syscalls
 
 # Tests which need libdl.
 ifeq (yes,$(build-shared))

misc/tst-syscalls.c

@@ -0,0 +1,167 @@
+/* Test for syscall interfaces.
+   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/>.  */
+
+/* This test verifies that the x32 system call handling zero-extends
+   unsigned 32-bit arguments to the 64-bit argument registers for
+   system calls (bug 25810).  The bug is specific to x32, but the test
+   should pass on all architectures.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <support/check.h>
+#include <support/xunistd.h>
+
+/* On x32, this can be passed in a single 64-bit integer register.  */
+struct Array
+{
+  size_t length;
+  void *ptr;
+};
+
+static int error_count;
+
+__attribute__ ((noclone, noinline))
+struct Array
+allocate (size_t bytes)
+{
+  if (!bytes)
+    return __extension__ (struct Array) {0, 0};
+
+  void *p = mmap (0x0, bytes, PROT_READ | PROT_WRITE,
+		  MAP_PRIVATE | MAP_ANON, -1, 0);
+  if (p == MAP_FAILED)
+    return __extension__ (struct Array) {0, 0};
+
+  return __extension__ (struct Array) {bytes, p};
+}
+
+__attribute__ ((noclone, noinline))
+void
+deallocate (struct Array b)
+{
+  /* On x32, the 64-bit integer register containing `b' may be copied
+     to another 64-bit integer register to pass the second argument to
+     munmap.  */
+  if (b.length && munmap (b.ptr, b.length))
+    {
+      printf ("munmap error: %m\n");
+      error_count++;
+    }
+}
+
+__attribute__ ((noclone, noinline))
+void *
+do_mmap (void *addr, size_t length)
+{
+  return mmap (addr, length, PROT_READ | PROT_WRITE,
+	       MAP_PRIVATE | MAP_ANON, -1, 0);
+}
+
+__attribute__ ((noclone, noinline))
+void *
+reallocate (struct Array b)
+{
+  /* On x32, the 64-bit integer register containing `b' may be copied
+     to another 64-bit integer register to pass the second argument to
+     do_mmap.  */
+  if (b.length)
+    return do_mmap (b.ptr, b.length);
+  return NULL;
+}
+
+__attribute__ ((noclone, noinline))
+void
+protect (struct Array b)
+{
+  if (b.length)
+    {
+      /* On x32, the 64-bit integer register containing `b' may be copied
+	 to another 64-bit integer register to pass the second argument
+	 to mprotect.  */
+      if (mprotect (b.ptr, b.length,
+		    PROT_READ | PROT_WRITE | PROT_EXEC))
+	{
+	  printf ("mprotect error: %m\n");
+	  error_count++;
+	}
+    }
+}
+
+__attribute__ ((noclone, noinline))
+ssize_t
+do_read (int fd, void *ptr, struct Array b)
+{
+  /* On x32, the 64-bit integer register containing `b' may be copied
+     to another 64-bit integer register to pass the second argument to
+     read.  */
+  if (b.length)
+    return read (fd, ptr, b.length);
+  return 0;
+}
+
+__attribute__ ((noclone, noinline))
+ssize_t
+do_write (int fd, void *ptr, struct Array b)
+{
+  /* On x32, the 64-bit integer register containing `b' may be copied
+     to another 64-bit integer register to pass the second argument to
+     write.  */
+  if (b.length)
+    return write (fd, ptr, b.length);
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  struct Array array;
+
+  array = allocate (1);
+  protect (array);
+  deallocate (array);
+  void *p = reallocate (array);
+  if (p == MAP_FAILED)
+    {
+      printf ("mmap error: %m\n");
+      error_count++;
+    }
+  array.ptr = p;
+  protect (array);
+  deallocate (array);
+
+  int fd = xopen ("/dev/null", O_RDWR, 0);
+  char buf[2];
+  array.ptr = buf;
+  if (do_read (fd, array.ptr, array) == -1)
+    {
+      printf ("read error: %m\n");
+      error_count++;
+    }
+  if (do_write (fd, array.ptr, array) == -1)
+    {
+      printf ("write error: %m\n");
+      error_count++;
+    }
+  xclose (fd);
+
+  return error_count ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+#include <support/test-driver.c>