[PATCH] arm64: Fix bit-shifting UB in MIDR_AMPERE1

[D Scott Phillips]

CONFIG_UBSAN_SHIFT with gcc-5 complains that shifting ARM_CPU_IMP_AMPERE
(0xC0) into bits [31:24] is undefined behavior. Well, sort of, it actually
spells the error as:

 /kisskb/src/arch/arm64/kernel/proton-pack.c: In function 'spectre_bhb_loop_affected':
 /kisskb/src/arch/arm64/include/asm/cputype.h:44:2: error: initializer element is not constant
   (((imp)   << MIDR_IMPLEMENTOR_SHIFT) | \
   ^

This isn't an issue for other Implementor codes, as all the other codes
have zero in the top bit.

Fixes: 0e5d5ae837c8ce04 ("arm64: Add AMPERE1 to the Spectre-BHB affected list")
Reported-by: Geert Uytterhoeven <geert at linux-m68k.org>
Signed-off-by: D Scott Phillips <scott at os.amperecomputing.com>
---
 arch/arm64/include/asm/cputype.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/include/asm/cputype.h b/arch/arm64/include/asm/cputype.h
index abc418650fec..b28db64799eb 100644
--- a/arch/arm64/include/asm/cputype.h
+++ b/arch/arm64/include/asm/cputype.h
@@ -60,7 +60,7 @@
 #define ARM_CPU_IMP_FUJITSU		0x46
 #define ARM_CPU_IMP_HISI		0x48
 #define ARM_CPU_IMP_APPLE		0x61
-#define ARM_CPU_IMP_AMPERE		0xC0
+#define ARM_CPU_IMP_AMPERE		0xC0u
 
 #define ARM_CPU_PART_AEM_V8		0xD0F
 #define ARM_CPU_PART_FOUNDATION		0xD00
-- 
2.37.3