[PATCH v2 23/37] arm64: kasan: Add arch layer for memory tagging helpers

Andrey Konovalov andreyknvl at google.com
Tue Sep 15 17:16:05 EDT 2020

This patch add a set of arch_*() memory tagging helpers currently only
defined for arm64 when hardware tag-based KASAN is enabled. These helpers
will be used by KASAN runtime to implement the hardware tag-based mode.

The arch-level indirection level is introduced to simplify adding hardware
tag-based KASAN support for other architectures in the future by defining
the appropriate arch_*() macros.

Signed-off-by: Andrey Konovalov <andreyknvl at google.com>
Co-developed-by: Vincenzo Frascino <vincenzo.frascino at arm.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino at arm.com>
Change-Id: I42b0795a28067872f8308e00c6f0195bca435c2a
 arch/arm64/include/asm/memory.h |  8 ++++++++
 mm/kasan/kasan.h                | 19 +++++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index e424fc3a68cb..268a3b6cebd2 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -231,6 +231,14 @@ static inline const void *__tag_set(const void *addr, u8 tag)
 	return (const void *)(__addr | __tag_shifted(tag));
+#define arch_init_tags(max_tag)			mte_init_tags(max_tag)
+#define arch_get_random_tag()			mte_get_random_tag()
+#define arch_get_mem_tag(addr)			mte_get_mem_tag(addr)
+#define arch_set_mem_tag_range(addr, size, tag)	\
+			mte_set_mem_tag_range((addr), (size), (tag))
+#endif /* CONFIG_KASAN_HW_TAGS */
  * Physical vs virtual RAM address space conversion.  These are
  * private definitions which should NOT be used outside memory.h
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 1d3c7c6ce771..8b43fc163ed1 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -240,6 +240,25 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag)
 #define reset_tag(addr)		((void *)arch_kasan_reset_tag(addr))
 #define get_tag(addr)		arch_kasan_get_tag(addr)
+#ifndef arch_init_tags
+#define arch_init_tags(max_tag)
+#ifndef arch_get_random_tag
+#define arch_get_random_tag()	(0xFF)
+#ifndef arch_get_mem_tag
+#define arch_get_mem_tag(addr)	(0xFF)
+#ifndef arch_set_mem_tag_range
+#define arch_set_mem_tag_range(addr, size, tag) ((void *)(addr))
+#define init_tags(max_tag)			arch_init_tags(max_tag)
+#define get_random_tag()			arch_get_random_tag()
+#define get_mem_tag(addr)			arch_get_mem_tag(addr)
+#define set_mem_tag_range(addr, size, tag)	\
+				arch_set_mem_tag_range((addr), (size), (tag))
  * Exported functions for interfaces called from assembly or from generated
  * code. Declarations here to avoid warning about missing declarations.

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