From e95c204297607d3e81aa2d8d964fc84a0015b333 Mon Sep 17 00:00:00 2001
From: andrew <andrew@FreeBSD.org>
Date: Thu, 21 Nov 2019 13:22:23 +0000
Subject: [PATCH] Add kcsan_md_unsupported from NetBSD.

It's used to ignore virtual addresses that may have a different physical
address depending on the CPU.

Sponsored by:	DARPA, AFRL
---
 sys/amd64/include/csan.h | 6 ++++++
 sys/arm64/include/csan.h | 6 ++++++
 sys/kern/subr_csan.c     | 2 ++
 3 files changed, 14 insertions(+)

diff --git a/sys/amd64/include/csan.h b/sys/amd64/include/csan.h
index 43c37dd1a541..c886daa12f69 100644
--- a/sys/amd64/include/csan.h
+++ b/sys/amd64/include/csan.h
@@ -35,6 +35,12 @@
 #include <machine/stack.h>
 #include <machine/vmparam.h>
 
+static inline bool
+kcsan_md_unsupported(vm_offset_t addr)
+{
+	return false;
+}
+
 static inline bool
 kcsan_md_is_avail(void)
 {
diff --git a/sys/arm64/include/csan.h b/sys/arm64/include/csan.h
index ddcd5972d06f..bace3866eb66 100644
--- a/sys/arm64/include/csan.h
+++ b/sys/arm64/include/csan.h
@@ -35,6 +35,12 @@
 #include <machine/stack.h>
 #include <machine/vmparam.h>
 
+static inline bool
+kcsan_md_unsupported(vm_offset_t addr)
+{
+	return false;
+}
+
 static inline bool
 kcsan_md_is_avail(void)
 {
diff --git a/sys/kern/subr_csan.c b/sys/kern/subr_csan.c
index b53bf4d74f01..e01dfb1c6293 100644
--- a/sys/kern/subr_csan.c
+++ b/sys/kern/subr_csan.c
@@ -151,6 +151,8 @@ kcsan_access(uintptr_t addr, size_t size, bool write, bool atomic, uintptr_t pc)
 
 	if (__predict_false(!kcsan_enabled))
 		return;
+	if (__predict_false(kcsan_md_unsupported((vm_offset_t)addr)))
+		return;
 
 	new.addr = addr;
 	new.size = size;