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.

6 files changed, 235 insertions, 0 deletions

diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile
index d8e06d27b2..d3ab37a40a 100644
--- a/sysdeps/aarch64/Makefile
+++ b/sysdeps/aarch64/Makefile
@@ -40,4 +40,9 @@ endif
 
 ifeq ($(subdir),misc)
 sysdep_headers += sys/ifunc.h
+sysdep_routines += __mtag_address_get_tag \
+		   __mtag_memset_tag \
+		   __mtag_new_tag \
+		   __mtag_tag_region
+
 endif
diff --git a/sysdeps/aarch64/__mtag_address_get_tag.S b/sysdeps/aarch64/__mtag_address_get_tag.S
new file mode 100644
index 0000000000..4ffe884c95
--- /dev/null
+++ b/sysdeps/aarch64/__mtag_address_get_tag.S
@@ -0,0 +1,32 @@
+/* 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
+#define ptr x0
+
+	.arch armv8.5-a
+	.arch_extension memtag
+
+ENTRY (__libc_mtag_address_get_tag)
+
+	ldg	ptr, [ptr]
+	ret
+END (__libc_mtag_address_get_tag)
+#endif /* USE_MTAG */
diff --git a/sysdeps/aarch64/__mtag_memset_tag.S b/sysdeps/aarch64/__mtag_memset_tag.S
new file mode 100644
index 0000000000..6f78d91b79
--- /dev/null
+++ b/sysdeps/aarch64/__mtag_memset_tag.S
@@ -0,0 +1,53 @@
+/* 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.  */
+#include "memset-reg.h"
+
+	.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 much better than
+   this for large values of COUNT.  */
+
+ENTRY(__libc_mtag_memset_with_tag)
+
+	and	valw, valw, 255
+	orr	valw, valw, valw, lsl 8
+	orr	valw, valw, valw, lsl 16
+	orr	val, val, val, lsl 32
+	mov	dst, dstin
+
+L(loop):
+	stgp	val, val, [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_memset_with_tag)
+#endif /* USE_MTAG */
diff --git a/sysdeps/aarch64/__mtag_new_tag.S b/sysdeps/aarch64/__mtag_new_tag.S
new file mode 100644
index 0000000000..663e3a484f
--- /dev/null
+++ b/sysdeps/aarch64/__mtag_new_tag.S
@@ -0,0 +1,37 @@
+/* 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
+
+	.arch armv8.5-a
+	.arch_extension memtag
+
+/* NB, only supported on variants with 64-bit pointers.  */
+
+#define ptr x0
+#define xset x1
+
+ENTRY(__libc_mtag_new_tag)
+	// Guarantee that the new tag is not the same as now.
+	gmi	xset, ptr, xzr
+	irg	ptr, ptr, xset
+	ret
+END (__libc_mtag_new_tag)
+#endif /* USE_MTAG */
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 */
diff --git a/sysdeps/aarch64/libc-mtag.h b/sysdeps/aarch64/libc-mtag.h
new file mode 100644
index 0000000000..a60c623777
--- /dev/null
+++ b/sysdeps/aarch64/libc-mtag.h
@@ -0,0 +1,57 @@
+/* libc-internal interface for tagged (colored) memory support.
+   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/>.  */
+
+#ifndef _AARCH64_LIBC_MTAG_H
+#define _AARCH64_LIBC_MTAG_H 1
+
+#ifndef USE_MTAG
+/* Generic bindings for systems that do not support memory tagging.  */
+#include_next "libc-mtag.h"
+#else
+
+/* Used to ensure additional alignment when objects need to have distinct
+   tags.  */
+#define __MTAG_GRANULE_SIZE 16
+
+/* Non-zero if memory obtained via morecore (sbrk) is not tagged.  */
+#define __MTAG_SBRK_UNTAGGED 1
+
+/* Extra flags to pass to mmap to get tagged pages.  */
+#define __MTAG_MMAP_FLAGS PROT_MTE
+
+/* Set the tags for a region of memory, which must have size and alignment
+   that are multiples of __MTAG_GRANULE_SIZE.  Size cannot be zero.
+   void *__libc_mtag_tag_region (const void *, size_t)  */
+void *__libc_mtag_tag_region (void *, size_t);
+
+/* Optimized equivalent to __libc_mtag_tag_region followed by memset.  */
+void *__libc_mtag_memset_with_tag (void *, int, size_t);
+
+/* Convert address P to a pointer that is tagged correctly for that
+   location.
+   void *__libc_mtag_address_get_tag (void*)  */
+void *__libc_mtag_address_get_tag (void *);
+
+/* Assign a new (random) tag to a pointer P (does not adjust the tag on
+   the memory addressed).
+   void *__libc_mtag_new_tag (void*)  */
+void *__libc_mtag_new_tag (void *);
+
+#endif /* USE_MTAG */
+
+#endif /* _AARCH64_LIBC_MTAG_H */