Detect invalid instruction masks at build time. Some versions of GCC can
warn about the situation, but not all of them, it seems.
Suggested-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
---
I couldn't manage to trigger the reported tautological-compare warning
with GCC 8.3.0, even when explicitly calling aarch64_insn_is_ldadd()
(since it's __always_inline) and even though the warning triggers when
inlining the test manually. So adding this check could be useful.
---
arch/arm64/include/asm/insn.h | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/arm64/include/asm/insn.h b/arch/arm64/include/asm/insn.h
index f71b84d9f294..87fdfba13a30 100644
--- a/arch/arm64/include/asm/insn.h
+++ b/arch/arm64/include/asm/insn.h
@@ -18,6 +18,7 @@
*/
#ifndef __ASM_INSN_H
#define __ASM_INSN_H
+#include <linux/build_bug.h>
#include <linux/types.h>
/* A64 instructions are always 32 bits. */
@@ -266,11 +267,16 @@ enum aarch64_insn_adr_type {
AARCH64_INSN_ADR_TYPE_ADR,
};
-#define __AARCH64_INSN_FUNCS(abbr, mask, val) \
-static __always_inline bool aarch64_insn_is_##abbr(u32 code) \
-{ return (code & (mask)) == (val); } \
-static __always_inline u32 aarch64_insn_get_##abbr##_value(void) \
-{ return (val); }
+#define __AARCH64_INSN_FUNCS(abbr, mask, val) \
+static __always_inline bool aarch64_insn_is_##abbr(u32 code) \
+{ \
+ BUILD_BUG_ON(~(mask) & (val)); \
+ return (code & (mask)) == (val); \
+} \
+static __always_inline u32 aarch64_insn_get_##abbr##_value(void) \
+{ \
+ return (val); \
+}
__AARCH64_INSN_FUNCS(adr, 0x9F000000, 0x10000000)
__AARCH64_INSN_FUNCS(adrp, 0x9F000000, 0x90000000)
--
2.21.0
