aarch64: Add aarch64-specific files for memory tagging support

This final patch provides the architecture-specific implementation of
the memory-tagging support hooks for aarch64.

1 files changed, 51 insertions, 0 deletions

diff --git a/sysdeps/aarch64/__mtag_tag_region.S b/sysdeps/aarch64/__mtag_tag_region.S
new file mode 100644
index 0000000000..7af4f0fa0a
--- /dev/null
+++ b/sysdeps/aarch64/__mtag_tag_region.S
@@ -0,0 +1,51 @@
+/* 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+#ifdef USE_MTAG
+
+/* Use the same register names and assignments as memset.  */
+
+	.arch armv8.5-a
+	.arch_extension memtag
+
+/* NB, only supported on variants with 64-bit pointers.  */
+
+/* FIXME: This is a minimal implementation.  We could do better than
+   this for larger values of COUNT.  */
+
+#define dstin x0
+#define count x1
+#define dst   x2
+
+ENTRY_ALIGN(__libc_mtag_tag_region, 6)
+
+	mov	dst, dstin
+L(loop):
+	stg	dst, [dst], #16
+	subs	count, count, 16
+	bne	L(loop)
+#if 0
+	/* This is not currently needed, since for now we are only called
+	   to tag memory that is taggable.  */
+	ldg	dstin, [dstin] // Recover the tag created (might be untagged).
+#endif
+	ret
+END (__libc_mtag_tag_region)
+#endif /* USE_MTAG */