Messages in this thread Patch in this message | | | From | Lin Yujun <> | Subject | [PATCH -next] arm64: Optimize the comparison of unsigned expressions to avoid compiling error | Date | Tue, 21 Feb 2023 09:27:40 +0800 |
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while compile arch/arm64/include/asm/cpufeature.h with -Werror=type-limits enabled, errors shown as below:
./arch/arm64/include/asm/cpufeature.h: In function 'system_supports_4kb_granule': ./arch/arm64/include/asm/cpufeature.h:653:14: error: comparison of unsigned expression >= 0 is always true [-Werror=type-limits] return (val >= ID_AA64MMFR0_TGRAN4_SUPPORTED_MIN) && ^~ ./arch/arm64/include/asm/cpufeature.h: In function 'system_supports_64kb_granule': ./arch/arm64/include/asm/cpufeature.h:666:14: error: comparison of unsigned expression >= 0 is always true [-Werror=type-limits] return (val >= ID_AA64MMFR0_TGRAN64_SUPPORTED_MIN) && ^~ Modify the return judgment statement, use "((val - min) < (val - max - 1))" to confirm that returns true in “min <= val <= max” cases, false in other cases.
Fixes: 79d82cbcbb3d ("arm64/kexec: Test page size support with new TGRAN range values") Signed-off-by: Lin Yujun <linyujun809@huawei.com> --- arch/arm64/include/asm/cpufeature.h | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 03d1c9d7af82..0a6bda025141 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -54,6 +54,9 @@ enum ftr_type { #define FTR_VISIBLE_IF_IS_ENABLED(config) \ (IS_ENABLED(config) ? FTR_VISIBLE : FTR_HIDDEN) +#define IN_RANGE_INCLUSIVE(val, min, max) \ + (((val) - (min)) < ((val) - (max) - 1)) + struct arm64_ftr_bits { bool sign; /* Value is signed ? */ bool visible; @@ -693,8 +696,9 @@ static inline bool system_supports_4kb_granule(void) val = cpuid_feature_extract_unsigned_field(mmfr0, ID_AA64MMFR0_EL1_TGRAN4_SHIFT); - return (val >= ID_AA64MMFR0_EL1_TGRAN4_SUPPORTED_MIN) && - (val <= ID_AA64MMFR0_EL1_TGRAN4_SUPPORTED_MAX); + return IN_RANGE_INCLUSIVE(val, + ID_AA64MMFR0_EL1_TGRAN4_SUPPORTED_MIN, + ID_AA64MMFR0_EL1_TGRAN4_SUPPORTED_MAX); } static inline bool system_supports_64kb_granule(void) @@ -706,8 +710,9 @@ static inline bool system_supports_64kb_granule(void) val = cpuid_feature_extract_unsigned_field(mmfr0, ID_AA64MMFR0_EL1_TGRAN64_SHIFT); - return (val >= ID_AA64MMFR0_EL1_TGRAN64_SUPPORTED_MIN) && - (val <= ID_AA64MMFR0_EL1_TGRAN64_SUPPORTED_MAX); + return IN_RANGE_INCLUSIVE(val, + ID_AA64MMFR0_EL1_TGRAN64_SUPPORTED_MIN, + ID_AA64MMFR0_EL1_TGRAN64_SUPPORTED_MAX); } static inline bool system_supports_16kb_granule(void) @@ -719,8 +724,9 @@ static inline bool system_supports_16kb_granule(void) val = cpuid_feature_extract_unsigned_field(mmfr0, ID_AA64MMFR0_EL1_TGRAN16_SHIFT); - return (val >= ID_AA64MMFR0_EL1_TGRAN16_SUPPORTED_MIN) && - (val <= ID_AA64MMFR0_EL1_TGRAN16_SUPPORTED_MAX); + return IN_RANGE_INCLUSIVE(val, + ID_AA64MMFR0_EL1_TGRAN16_SUPPORTED_MIN, + ID_AA64MMFR0_EL1_TGRAN16_SUPPORTED_MAX); } static inline bool system_supports_mixed_endian_el0(void) -- 2.34.1
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