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/*
* Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file is distributed
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
* express or implied. See the License for the specific language governing
* permissions and limitations under the License.
*/
#include "s2n_pq.h"
#include "crypto/s2n_openssl.h"
static bool kyber512r3_avx2_bmi2_enabled = false;
#if defined(S2N_CPUID_AVAILABLE)
/* https://en.wikipedia.org/wiki/CPUID */
#include <cpuid.h>
#define PROCESSOR_INFO_AND_FEATURES 1
#define EXTENDED_FEATURES_LEAF 7
#define EXTENDED_FEATURES_SUBLEAF_ZERO 0
/* The cpuid.h header included with older versions of gcc and
* clang doesn't include definitions for bit_ADX, bit_BMI2, or
* __get_cpuid_count(). */
#if !defined(bit_BMI2)
#define bit_BMI2 (1 << 8)
#endif
#define EBX_BIT_AVX2 (1 << 5)
bool s2n_get_cpuid_count(uint32_t leaf, uint32_t sub_leaf, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx) {
/* 0x80000000 probes for extended cpuid info */
uint32_t max_level = __get_cpuid_max(leaf & 0x80000000, 0);
if (max_level == 0 || max_level < leaf) {
return false;
}
__cpuid_count(leaf, sub_leaf, *eax, *ebx, *ecx, *edx);
return true;
}
/* https://en.wikipedia.org/wiki/Bit_manipulation_instruction_set#BMI2_(Bit_Manipulation_Instruction_Set_2) */
bool s2n_cpu_supports_bmi2() {
uint32_t eax, ebx, ecx, edx;
if (!s2n_get_cpuid_count(EXTENDED_FEATURES_LEAF, EXTENDED_FEATURES_SUBLEAF_ZERO, &eax, &ebx, &ecx, &edx)) {
return false;
}
return (ebx & bit_BMI2);
}
bool s2n_cpu_supports_avx2() {
uint32_t eax, ebx, ecx, edx;
if (!s2n_get_cpuid_count(EXTENDED_FEATURES_LEAF, EXTENDED_FEATURES_SUBLEAF_ZERO, &eax, &ebx, &ecx, &edx)) {
return false;
}
return (ebx & EBX_BIT_AVX2);
}
bool s2n_cpu_supports_kyber512r3_avx2_bmi2() {
#if defined(S2N_KYBER512R3_AVX2_BMI2)
return s2n_cpu_supports_bmi2() && s2n_cpu_supports_avx2();
#else
return false;
#endif
}
#else /* defined(S2N_CPUID_AVAILABLE) */
/* If CPUID is not available, we cannot perform necessary run-time checks. */
bool s2n_cpu_supports_kyber512r3_avx2_bmi2() {
return false;
}
#endif /* defined(S2N_CPUID_AVAILABLE) */
bool s2n_kyber512r3_is_avx2_bmi2_enabled() {
return kyber512r3_avx2_bmi2_enabled;
}
bool s2n_pq_is_enabled() {
#if defined(S2N_NO_PQ)
return false;
#else
/* aws-lc is currently the only supported FIPS library known to support PQ. */
return s2n_libcrypto_is_awslc() || (!s2n_is_in_fips_mode());
#endif
}
S2N_RESULT s2n_disable_kyber512r3_opt_avx2_bmi2() {
kyber512r3_avx2_bmi2_enabled = false;
return S2N_RESULT_OK;
}
S2N_RESULT s2n_try_enable_kyber512r3_opt_avx2_bmi2() {
if (s2n_pq_is_enabled() && s2n_cpu_supports_kyber512r3_avx2_bmi2()) {
kyber512r3_avx2_bmi2_enabled = true;
}
return S2N_RESULT_OK;
}
S2N_RESULT s2n_pq_init() {
RESULT_ENSURE_OK(s2n_try_enable_kyber512r3_opt_avx2_bmi2(), S2N_ERR_SAFETY);
return S2N_RESULT_OK;
}
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