cpuid_arm32.cpp

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/*
* Runtime CPU detection for 32-bit ARM
* (C) 2009,2010,2013,2017,2024 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/internal/cpuid.h>
 
#include <botan/internal/target_info.h>
 
#if defined(BOTAN_HAS_OS_UTILS)
   #include <botan/internal/os_utils.h>
#endif
 
namespace Botan {
 
uint32_t CPUID::CPUID_Data::detect_cpu_features(uint32_t allowed) {
   uint32_t feat = 0;
 
#if defined(BOTAN_HAS_OS_UTILS)
 
   if(auto auxval = OS::get_auxval_hwcap()) {
      const auto [hwcap_neon, hwcap_crypto] = *auxval;
 
      /*
      * On systems with getauxval these bits should normally be defined
      * in bits/auxv.h but some buggy? glibc installs seem to miss them.
      * These following values are all fixed, for the Linux ELF format,
      * so we just hardcode them in ARM_hwcap_bit enum.
      */
 
      enum class ARM_hwcap_bit : uint64_t {
         NEON_bit = (1 << 12),
         AES_bit = (1 << 0),
         PMULL_bit = (1 << 1),
         SHA1_bit = (1 << 2),
         SHA2_bit = (1 << 3),
      };
 
      feat |= if_set(hwcap_neon, ARM_hwcap_bit::NEON_bit, CPUFeature::Bit::NEON, allowed);
 
      if(feat & CPUFeature::Bit::NEON) {
         feat |= if_set(hwcap_crypto, ARM_hwcap_bit::AES_bit, CPUFeature::Bit::AES, allowed);
         feat |= if_set(hwcap_crypto, ARM_hwcap_bit::PMULL_bit, CPUFeature::Bit::PMULL, allowed);
         feat |= if_set(hwcap_crypto, ARM_hwcap_bit::SHA1_bit, CPUFeature::Bit::SHA1, allowed);
         feat |= if_set(hwcap_crypto, ARM_hwcap_bit::SHA2_bit, CPUFeature::Bit::SHA2, allowed);
      }
   }
#endif
 
   return feat;
}
 
}  // namespace Botan