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Groups > linux.kernel > #1272387

[PATCH 1/5] arm64: cpufeature: Add helpers for extracting unsigned values

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The cpuid_feature_extract_field() extracts the feature value
as a signed integer. This could be problematic for features
whose values are unsigned. e.g, ID_AA64DFR0_EL1:BRPs. Add
an unsigned variant for the unsigned fields.

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reported-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
---
 arch/arm64/include/asm/cpufeature.h |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 11d5bb0f..7a16102 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -123,6 +123,18 @@ cpuid_feature_extract_field(u64 features, int field)
 	return cpuid_feature_extract_field_width(features, field, 4);
 }
 
+static inline unsigned int __attribute_const__
+cpuid_feature_extract_unsigned_field_width(u64 features, int field, int width)
+{
+	return (u64)(features << (64 - width - field)) >> (64 - width);
+}
+
+static inline unsigned int __attribute_const__
+cpuid_feature_extract_unsigned_field(u64 features, int field)
+{
+	return cpuid_feature_extract_unsigned_field_width(features, field, 4);
+}
+
 static inline u64 arm64_ftr_mask(struct arm64_ftr_bits *ftrp)
 {
 	return (u64)GENMASK(ftrp->shift + ftrp->width - 1, ftrp->shift);
-- 
1.7.9.5

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Thread

[PATCH 0/5] arm64: cpufeature: Fixes for 4.4-rc1 "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-11-18 18:10 +0100
  [PATCH 1/5] arm64: cpufeature: Add helpers for extracting unsigned values "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-11-18 18:10 +0100
    [PATCH 4/5] arm64: Make fail_incapable_cpu reusable "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-11-18 18:10 +0100
    [PATCH 2/5] arm64: cpufeature: Track unsigned fields "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-11-18 18:10 +0100
      Re: [PATCH 2/5] arm64: cpufeature: Track unsigned fields AKASHI Takahiro <takahiro.akashi@linaro.org> - 2015-11-19 06:00 +0100
        Re: [PATCH 2/5] arm64: cpufeature: Track unsigned fields "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-11-19 11:10 +0100
          Re: [PATCH 2/5] arm64: cpufeature: Track unsigned fields "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-11-19 11:10 +0100
          Re: [PATCH 2/5] arm64: cpufeature: Track unsigned fields Catalin Marinas <catalin.marinas@arm.com> - 2015-11-19 19:50 +0100
            Re: [PATCH 2/5] arm64: cpufeature: Track unsigned fields "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-11-20 14:40 +0100
    [PATCH 5/5] arm64: Ensure the secondary CPUs have safe ASIDBits size "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-11-18 18:10 +0100
      Re: [PATCH 5/5] arm64: Ensure the secondary CPUs have safe ASIDBits  size Will Deacon <will.deacon@arm.com> - 2015-11-23 18:30 +0100
        Re: [PATCH 5/5] arm64: Ensure the secondary CPUs have safe ASIDBits  size "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-11-24 00:50 +0100
    [PATCH 3/5] arm64: debug: Treat the BRPs/WRPs as unsigned "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-11-18 18:20 +0100
      Re: [PATCH 3/5] arm64: debug: Treat the BRPs/WRPs as unsigned Will Deacon <will.deacon@arm.com> - 2015-11-23 18:40 +0100
  Re: [PATCH 0/5] arm64: cpufeature: Fixes for 4.4-rc1 Catalin Marinas <catalin.marinas@arm.com> - 2015-11-26 19:20 +0100

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