Hi,
On 12/08/2025 14:23, Maciej Wieczor-Retman wrote:
From: Samuel Holland <samuel.holland@xxxxxxxxxx>
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.
Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@xxxxxxxxx>
---
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
Building CONFIG_KASAN_HW_TAGS with -Werror on arm64 fails here
due to a warning about KASAN_TAG_MIN being redefined.
On my side the error got triggered when compiling
arch/arm64/kernel/asm-offsets.c due to the ordering of some includes :
from <asm/processor.h>, <linux/kasan-tags.h> ends up being included
(by <asm/cpufeatures.h> including <asm/sysreg.h>) before <asm/kasan.h>.
(Build trace at the end for reference)
Adding `#undef KASAN_TAG_MIN` before redefining the arch version
allows building CONFIG_KASAN_HW_TAGS on arm64 without
further issues, but I don't know if this is most appropriate fix.Thanks,
Ada ---
CC arch/arm64/kernel/asm-offsets.s
In file included from ./arch/arm64/include/asm/processor.h:42,
from ./include/asm-generic/qrwlock.h:18,
from ./arch/arm64/include/generated/asm/qrwlock.h:1,
from ./arch/arm64/include/asm/spinlock.h:9,
from ./include/linux/spinlock.h:95,
from ./include/linux/mmzone.h:8,
from ./include/linux/gfp.h:7,
from ./include/linux/slab.h:16,
from ./include/linux/resource_ext.h:11,
from ./include/linux/acpi.h:13,
from ./include/acpi/apei.h:9,
from ./include/acpi/ghes.h:5,
from ./include/linux/arm_sdei.h:8,
from ./arch/arm64/kernel/asm-offsets.c:10:
./arch/arm64/include/asm/kasan.h:11: error: "KASAN_TAG_MIN" redefined [-Werror]
11 | #define KASAN_TAG_MIN 0xF0 /* minimum value for random tags */
|
In file included from ./arch/arm64/include/asm/sysreg.h:14,
from ./arch/arm64/include/asm/cputype.h:250,
from ./arch/arm64/include/asm/cache.h:43,
from ./include/vdso/cache.h:5,
from ./include/linux/cache.h:6,
from ./include/linux/slab.h:15:
./include/linux/kasan-tags.h:23: note: this is the location of the previous definition
23 | #define KASAN_TAG_MIN 0x00 /* minimum value for random tags */
|
