[PATCH v10 08/22] kasan, arm64: untag address in __kimg_to_phys and _virt_addr_is_linear

[Andrey Konovalov]

__kimg_to_phys (which is used by virt_to_phys) and _virt_addr_is_linear
(which is used by virt_addr_valid) assume that the top byte of the address
is 0xff, which isn't always the case with tag-based KASAN.

This patch resets the tag in those macros.

Reviewed-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
---
 arch/arm64/include/asm/memory.h | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 0f1e024a951f..3226a0218b0b 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -92,6 +92,15 @@
 #define KASAN_THREAD_SHIFT	0
 #endif
 
+#ifdef CONFIG_KASAN_SW_TAGS
+#define KASAN_TAG_SHIFTED(tag)		((unsigned long)(tag) << 56)
+#define KASAN_SET_TAG(addr, tag)	(((addr) & ~KASAN_TAG_SHIFTED(0xff)) | \
+						KASAN_TAG_SHIFTED(tag))
+#define KASAN_RESET_TAG(addr)		KASAN_SET_TAG(addr, 0xff)
+#else
+#define KASAN_RESET_TAG(addr)		addr
+#endif
+
 #define MIN_THREAD_SHIFT	(14 + KASAN_THREAD_SHIFT)
 
 /*
@@ -232,7 +241,7 @@ static inline unsigned long kaslr_offset(void)
 #define __is_lm_address(addr)	(!!((addr) & BIT(VA_BITS - 1)))
 
 #define __lm_to_phys(addr)	(((addr) & ~PAGE_OFFSET) + PHYS_OFFSET)
-#define __kimg_to_phys(addr)	((addr) - kimage_voffset)
+#define __kimg_to_phys(addr)	(KASAN_RESET_TAG(addr) - kimage_voffset)
 
 #define __virt_to_phys_nodebug(x) ({					\
 	phys_addr_t __x = (phys_addr_t)(x);				\
@@ -308,7 +317,8 @@ static inline void *phys_to_virt(phys_addr_t x)
 #endif
 #endif
 
-#define _virt_addr_is_linear(kaddr)	(((u64)(kaddr)) >= PAGE_OFFSET)
+#define _virt_addr_is_linear(kaddr)	(KASAN_RESET_TAG((u64)(kaddr)) >= \
+						PAGE_OFFSET)
 #define virt_addr_valid(kaddr)		(_virt_addr_is_linear(kaddr) && \
 					 _virt_addr_valid(kaddr))
 
-- 
2.19.1.930.g4563a0d9d0-goog