[PATCH v1 06/16] khwasan, arm64: untag virt address in __kimg_to_phys

[Andrey Konovalov <andreyknvl@google.com>]

__kimg_to_phys (which is used by virt_to_phys) assumes that the top byte
of the address is 0xff, which isn't always the case with KHWASAN enabled.
The solution is to reset the tag in __kimg_to_phys.

__lm_to_phys doesn't require any fixups, as it zeroes out the top byte
with the current implementation.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
 arch/arm64/include/asm/memory.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 6d084431b7f7..f206273469b5 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -92,6 +92,12 @@
 #define KASAN_THREAD_SHIFT	0
 #endif
 
+#ifdef CONFIG_KASAN_HW
+#define KASAN_TAG_SHIFTED(tag)		((unsigned long)(tag) << 56)
+#define KASAN_SET_TAG(addr, tag)	(((addr) & ~KASAN_TAG_SHIFTED(0xff)) | \
+						KASAN_TAG_SHIFTED(tag))
+#endif
+
 #define MIN_THREAD_SHIFT	(14 + KASAN_THREAD_SHIFT)
 
 /*
@@ -225,7 +231,12 @@ 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)
+
+#ifdef CONFIG_KASAN_HW
+#define __kimg_to_phys(addr)	(KASAN_SET_TAG((addr), 0xff) - kimage_voffset)
+#else
 #define __kimg_to_phys(addr)	((addr) - kimage_voffset)
+#endif
 
 #define __virt_to_phys_nodebug(x) ({					\
 	phys_addr_t __x = (phys_addr_t)(x);				\
-- 
2.17.0.441.gb46fe60e1d-goog