[PATCH v2] xen/arm: Avoid overflow using MIDR_IMPLEMENTOR_MASK

[Michal Orzel <michal.orzel@xxxxxxx>]

Value of macro MIDR_IMPLEMENTOR_MASK exceeds the range of integer
and can lead to overflow. Currently there is no issue as it is used
in an expression implicitly casted to u32 in MIDR_IS_CPU_MODEL_RANGE.
To avoid possible problems, fix the macro.

Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
Link: https://lore.kernel.org/r/20220426070603.56031-1-michal.orzel@xxxxxxx
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Origin: git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git (48e6f22e25a4)
---
Changes since v1:
- add Origin tag as the patch was merged in upstream arm64 linux tree
---
 xen/arch/arm/include/asm/processor.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/arm/include/asm/processor.h 
b/xen/arch/arm/include/asm/processor.h
index 852b5f3c24..7a1c4c4410 100644
--- a/xen/arch/arm/include/asm/processor.h
+++ b/xen/arch/arm/include/asm/processor.h
@@ -39,7 +39,7 @@
 #define MIDR_VARIANT(midr) \
     (((midr) & MIDR_VARIANT_MASK) >> MIDR_VARIANT_SHIFT)
 #define MIDR_IMPLEMENTOR_SHIFT  24
-#define MIDR_IMPLEMENTOR_MASK   (0xff << MIDR_IMPLEMENTOR_SHIFT)
+#define MIDR_IMPLEMENTOR_MASK   (0xffU << MIDR_IMPLEMENTOR_SHIFT)
 #define MIDR_IMPLEMENTOR(midr) \
     (((midr) & MIDR_IMPLEMENTOR_MASK) >> MIDR_IMPLEMENTOR_SHIFT)
 
-- 
2.25.1