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[PATCH] x86: Correct index_cpu_LZCNT [BZ # 23456]
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: libc-alpha at sourceware dot org
- Date: Thu, 26 Jul 2018 09:46:50 -0700
- Subject: [PATCH] x86: Correct index_cpu_LZCNT [BZ # 23456]
cpu-features.h has
#define bit_cpu_LZCNT (1 << 5)
#define index_cpu_LZCNT COMMON_CPUID_INDEX_1
#define reg_LZCNT
But the LZCNT feature bit is in COMMON_CPUID_INDEX_80000001:
Initial EAX Value: 80000001H
ECX Extended Processor Signature and Feature Bits:
Bit 05: LZCNT available
index_cpu_LZCNT should be COMMON_CPUID_INDEX_80000001, not
COMMON_CPUID_INDEX_1. The VMX feature bit is in COMMON_CPUID_INDEX_1:
Initial EAX Value: 01H
Feature Information Returned in the ECX Register:
5 VMX
[BZ # 23456]
* sysdeps/x86/cpu-features.h (index_cpu_LZCNT): Set to
COMMON_CPUID_INDEX_80000001.
---
sysdeps/x86/cpu-features.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sysdeps/x86/cpu-features.h b/sysdeps/x86/cpu-features.h
index 624e681e96..3807a9d611 100644
--- a/sysdeps/x86/cpu-features.h
+++ b/sysdeps/x86/cpu-features.h
@@ -204,7 +204,7 @@ extern const struct cpu_features *__get_cpu_features (void)
# define index_cpu_HTT COMMON_CPUID_INDEX_1
# define index_cpu_BMI1 COMMON_CPUID_INDEX_7
# define index_cpu_BMI2 COMMON_CPUID_INDEX_7
-# define index_cpu_LZCNT COMMON_CPUID_INDEX_1
+# define index_cpu_LZCNT COMMON_CPUID_INDEX_80000001
# define index_cpu_MOVBE COMMON_CPUID_INDEX_1
# define index_cpu_POPCNT COMMON_CPUID_INDEX_1
# define index_cpu_IBT COMMON_CPUID_INDEX_7
--
2.17.1