On Wed, Aug 14, 2019 at 04:20:18PM +0100, Mark Rutland wrote:

Hi Steve,

Hi Mark,

On Wed, Aug 07, 2019 at 04:55:15PM +0100, Steve Capper wrote:

quoted

+config KASAN_SHADOW_OFFSET
+	hex
+	depends on KASAN
+	default 0xdfffa00000000000 if (ARM64_VA_BITS_48 || ARM64_USER_VA_BITS_52) && !KASAN_SW_TAGS
+	default 0xdfffd00000000000 if ARM64_VA_BITS_47 && !KASAN_SW_TAGS
+	default 0xdffffe8000000000 if ARM64_VA_BITS_42 && !KASAN_SW_TAGS
+	default 0xdfffffd000000000 if ARM64_VA_BITS_39 && !KASAN_SW_TAGS
+	default 0xdffffffa00000000 if ARM64_VA_BITS_36 && !KASAN_SW_TAGS
+	default 0xefff900000000000 if (ARM64_VA_BITS_48 || ARM64_USER_VA_BITS_52) && KASAN_SW_TAGS
+	default 0xefffc80000000000 if ARM64_VA_BITS_47 && KASAN_SW_TAGS
+	default 0xeffffe4000000000 if ARM64_VA_BITS_42 && KASAN_SW_TAGS
+	default 0xefffffc800000000 if ARM64_VA_BITS_39 && KASAN_SW_TAGS
+	default 0xeffffff900000000 if ARM64_VA_BITS_36 && KASAN_SW_TAGS
+	default 0xffffffffffffffff
+
 source "arch/arm64/Kconfig.platforms"
 
 menu "Kernel Features"

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index b2400f9c1213..2b7db0d41498 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile

@@ -126,14 +126,6 @@ KBUILD_CFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
 KBUILD_CPPFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
 KBUILD_AFLAGS += -DKASAN_SHADOW_SCALE_SHIFT=$(KASAN_SHADOW_SCALE_SHIFT)
 
-# KASAN_SHADOW_OFFSET = VA_START + (1 << (VA_BITS - KASAN_SHADOW_SCALE_SHIFT))
-#				 - (1 << (64 - KASAN_SHADOW_SCALE_SHIFT))
-# in 32-bit arithmetic
-KASAN_SHADOW_OFFSET := $(shell printf "0x%08x00000000\n" $$(( \
-	(0xffffffff & (-1 << ($(CONFIG_ARM64_VA_BITS) - 1 - 32))) \
-	+ (1 << ($(CONFIG_ARM64_VA_BITS) - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) \
-	- (1 << (64 - 32 - $(KASAN_SHADOW_SCALE_SHIFT))) )) )
-
 export	TEXT_OFFSET GZFLAGS
 
 core-y		+= arch/arm64/kernel/ arch/arm64/mm/

I've just spotted this breaks build using CONFIG_KASAN_SW_TAGS &&
CONFIG_KASAN_INLINE, as scripts/Makefile.kasan only propagates
CONFIG_KASAN_SHADOW_OFFSET into KASAN_SHADOW_OFFSET when
CONFIG_KASAN_GENERIC is selected, but consumes KASAN_SHADOW_OFFSET
regardless.

I think that's by accident rather than by design, but to
minimize/localize the fixup, how about the below? I can send a cleanup
patch for scripts/Makefile.kasan later.

Build and boot tested with CONFIG_KASAN_{SW_TAGS,GENERIC} and
VA_BITS_52 (on a 48-bit VA system).

I've tested this with VA_BITS_52 (booted with 52-bit) with inline
SW_TAGS and generic KASAN.

FWIW:
Tested-by: Steve Capper <redacted>
Reviewed-by: Steve Capper <redacted>

Agreed for this small fix now and a bigger fix in Makefile.kasan later.

Cheers,
-- 
Steve

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