Allow architectures to override KASAN_TAG_KERNEL in asm/kasan.h. This
is needed on RISC-V, which supports 57-bit virtual addresses and 7-bit
pointer tags. For consistency, move the arm64 MTE definition of
KASAN_TAG_MIN to asm/kasan.h, since it is also architecture-dependent;
RISC-V's equivalent extension is expected to support 7-bit hardware
memory tags.

Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
---

 arch/arm64/include/asm/kasan.h   |  6 ++++--
 arch/arm64/include/asm/uaccess.h |  1 +
 include/linux/kasan-tags.h       | 13 ++++++++-----
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/include/asm/kasan.h b/arch/arm64/include/asm/kasan.h
index e1b57c13f8a4..4ab419df8b93 100644
--- a/arch/arm64/include/asm/kasan.h
+++ b/arch/arm64/include/asm/kasan.h

@@ -6,8 +6,10 @@

 #include <linux/linkage.h>
 #include <asm/memory.h>
-#include <asm/mte-kasan.h>
-#include <asm/pgtable-types.h>
+
+#ifdef CONFIG_KASAN_HW_TAGS
+#define KASAN_TAG_MIN                  0xF0 /* minimum value for random tags */
+#endif

 #define arch_kasan_set_tag(addr, tag)  __tag_set(addr, tag)
 #define arch_kasan_reset_tag(addr)     __tag_reset(addr)

diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 28f665e0975a..56a09f412272 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h

@@ -22,6 +22,7 @@
 #include <asm/cpufeature.h>
 #include <asm/mmu.h>
 #include <asm/mte.h>
+#include <asm/mte-kasan.h>
 #include <asm/ptrace.h>
 #include <asm/memory.h>
 #include <asm/extable.h>

diff --git a/include/linux/kasan-tags.h b/include/linux/kasan-tags.h
index 4f85f562512c..e07c896f95d3 100644
--- a/include/linux/kasan-tags.h
+++ b/include/linux/kasan-tags.h

@@ -2,13 +2,16 @@
 #ifndef _LINUX_KASAN_TAGS_H
 #define _LINUX_KASAN_TAGS_H

+#include <asm/kasan.h>
+
+#ifndef KASAN_TAG_KERNEL
 #define KASAN_TAG_KERNEL       0xFF /* native kernel pointers tag */
-#define KASAN_TAG_INVALID      0xFE /* inaccessible memory tag */
-#define KASAN_TAG_MAX          0xFD /* maximum value for random tags */
+#endif
+
+#define KASAN_TAG_INVALID      (KASAN_TAG_KERNEL - 1) /* inaccessible memory tag */
+#define KASAN_TAG_MAX          (KASAN_TAG_KERNEL - 2) /* maximum value for random tags */

-#ifdef CONFIG_KASAN_HW_TAGS
-#define KASAN_TAG_MIN          0xF0 /* minimum value for random tags */
-#else
+#ifndef KASAN_TAG_MIN
 #define KASAN_TAG_MIN          0x00 /* minimum value for random tags */
 #endif

--

2.45.1