From 90010126b03b098edc70a5a0e63c1c0a65cd47fb Mon Sep 17 00:00:00 2001
From: Mark Johnston <markj@FreeBSD.org>
Date: Thu, 8 Feb 2024 11:00:40 -0500
Subject: [PATCH] arm64: Add msan.h

This is mostly a copy of amd64's msan.h, except that we currently do not
avoid shadowing the kernel itself, and we need a more restrictive upper
bound in kmsan_md_unsupported() to avoid probing non-existent shadow
mappings of device mappings.

Reviewed by:	imp
MFC after:	2 weeks
Sponsored by:	Klara, Inc.
Sponsored by:	Juniper Networks, Inc.
Differential Revision:	https://reviews.freebsd.org/D43156
---
 sys/arm64/include/msan.h | 91 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 sys/arm64/include/msan.h

diff --git a/sys/arm64/include/msan.h b/sys/arm64/include/msan.h
new file mode 100644
index 000000000000..48be55af44b6
--- /dev/null
+++ b/sys/arm64/include/msan.h
@@ -0,0 +1,91 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2021 The FreeBSD Foundation
+ * Copyright (c) 2023 Juniper Networks, Inc.
+ *
+ * This software was developed by Mark Johnston under sponsorship from the
+ * FreeBSD Foundation.
+ *
+ * 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, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, 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 AUTHOR AND CONTRIBUTORS ``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 AUTHOR OR CONTRIBUTORS 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.
+ */
+
+#ifndef _MACHINE_MSAN_H_
+#define	_MACHINE_MSAN_H_
+
+#ifdef KMSAN
+
+#include <vm/vm.h>
+#include <vm/pmap.h>
+#include <vm/vm_page.h>
+#include <machine/vmparam.h>
+
+typedef uint32_t msan_orig_t;
+
+/*
+ * Our 32-bit origin cells encode a 2-bit type and 30-bit pointer to a kernel
+ * instruction.  The pointer is compressed by making it a positive offset
+ * relative to KERNBASE.
+ */
+#define	KMSAN_ORIG_TYPE_SHIFT	30u
+#define	KMSAN_ORIG_PTR_MASK	((1ul << KMSAN_ORIG_TYPE_SHIFT) - 1)
+
+static inline msan_orig_t
+kmsan_md_orig_encode(int type, uintptr_t ptr)
+{
+	return ((type << KMSAN_ORIG_TYPE_SHIFT) |
+	    ((ptr & KMSAN_ORIG_PTR_MASK)));
+}
+
+static inline void
+kmsan_md_orig_decode(msan_orig_t orig, int *type, uintptr_t *ptr)
+{
+	*type = orig >> KMSAN_ORIG_TYPE_SHIFT;
+	*ptr = (orig & KMSAN_ORIG_PTR_MASK) | KERNBASE;
+}
+
+static inline vm_offset_t
+kmsan_md_addr_to_shad(vm_offset_t addr)
+{
+	return (addr - VM_MIN_KERNEL_ADDRESS + KMSAN_SHAD_MIN_ADDRESS);
+}
+
+static inline vm_offset_t
+kmsan_md_addr_to_orig(vm_offset_t addr)
+{
+	return (addr - VM_MIN_KERNEL_ADDRESS + KMSAN_ORIG_MIN_ADDRESS);
+}
+
+static inline bool
+kmsan_md_unsupported(vm_offset_t addr)
+{
+	/*
+	 * It would be cheaper to use VM_MAX_KERNEL_ADDRESS as the upper bound,
+	 * but we need to exclude device mappings above kernel_vm_end but within
+	 * the kernel map.
+	 */
+	return (addr < VM_MIN_KERNEL_ADDRESS || addr >= kernel_vm_end);
+}
+
+#endif /* KMSAN */
+
+#endif /* !_MACHINE_MSAN_H_ */