cpuid_arm.hpp

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#include <nil/crypto3/utilities/cpuid/cpuid.hpp>
 
#if defined(BOOST_ARCH_ARM)
 
#if defined(CRYPTO3_TARGET_OS_HAS_GETAUXVAL)
#include <sys/auxv.h>
 
#elif defined(CRYPTO3_TARGET_OS_IS_IOS)
#include <sys/types.h>
#include <sys/sysctl.h>
 
#else
#include <nil/crypto3/utilities/os_utils.h>
 
#endif
 
#endif
 
namespace nil {
    namespace crypto3 {
 
#if defined(BOOST_ARCH_ARM)
 
#if defined(CRYPTO3_TARGET_OS_IS_IOS)
 
        namespace {
 
            uint64_t flags_by_ios_machine_type(const std::string &machine) {
                /*
                 * This relies on a map of known machine names to features. This
                 * will quickly grow out of date as new products are introduced, but
                 * is apparently the best we can do for iOS.
                 */
 
                struct version_info {
                    std::string name;
                    size_t min_version_neon;
                    size_t min_version_armv8;
                };
 
                static const version_info min_versions[] = {
                    {"iPhone", 2, 6},
                    {"iPad", 1, 4},
                    {"iPod", 4, 7},
                    {"AppleTV", 2, 5},
                };
 
                if (machine.size() < 3)
                    return 0;
 
                auto comma = machine.find(',');
 
                // Simulator, or something we don't know about
                if (comma == std::string::npos)
                    return 0;
 
                std::string product = machine.substr(0, comma);
 
                size_t version = 0;
                size_t place = 1;
                while (product.size() > 1 && ::isdigit(product.back())) {
                    const size_t digit = product.back() - '0';
                    version += digit * place;
                    place *= 10;
                    product.pop_back();
                }
 
                if (version == 0)
                    return 0;
 
                for (const version_info &info : min_versions) {
                    if (info.name != product)
                        continue;
 
                    if (version >= info.min_version_armv8) {
                        return cpuid::CPUID_ARM_RIJNDAEL_BIT | cpuid::CPUID_ARM_PMULL_BIT | cpuid::CPUID_ARM_SHA1_BIT |
                               cpuid::CPUID_ARM_SHA2_BIT | cpuid::CPUID_ARM_NEON_BIT;
                    }
 
                    if (version >= info.min_version_neon)
                        return cpuid::CPUID_ARM_NEON_BIT;
                }
 
                // Some other product we don't know about
                return 0;
            }
 
        }    // namespace
 
#endif
 
        uint64_t cpuid::detect_cpu_features(size_t *cache_line_size) {
            uint64_t detected_features = 0;
 
#if defined(CRYPTO3_TARGET_OS_HAS_GETAUXVAL)
            /*
             * 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 ARM_hwcap_bit {
#if defined(CRYPTO3_TARGET_ARCHITECTURE_IS_ARM32)
                NEON_bit = (1 << 12),
                AES_bit = (1 << 0),
                PMULL_bit = (1 << 1),
                SHA1_bit = (1 << 2),
                SHA2_bit = (1 << 3),
 
                ARCH_hwcap_neon = 16,      // AT_HWCAP
                ARCH_hwcap_crypto = 26,    // AT_HWCAP2
#elif defined(CRYPTO3_TARGET_ARCHITECTURE_IS_ARM64)
                NEON_bit = (1 << 1),
                AES_bit = (1 << 3),
                PMULL_bit = (1 << 4),
                SHA1_bit = (1 << 5),
                SHA2_bit = (1 << 6),
 
                ARCH_hwcap_neon = 16,      // AT_HWCAP
                ARCH_hwcap_crypto = 16,    // AT_HWCAP
#endif
            };
 
#if defined(AT_DCACHEBSIZE)
            const unsigned long dcache_line = ::getauxval(AT_DCACHEBSIZE);
 
            // plausibility check
            if (dcache_line == 32 || dcache_line == 64 || dcache_line == 128)
                *cache_line_size = static_cast<size_t>(dcache_line);
#endif
 
            const unsigned long hwcap_neon = ::getauxval(ARM_hwcap_bit::ARCH_hwcap_neon);
            if (hwcap_neon & ARM_hwcap_bit::NEON_bit)
                detected_features |= cpuid::CPUID_ARM_NEON_BIT;
 
            /*
            On aarch64 this ends up calling getauxval twice with AT_HWCAP
            It doesn't seem worth optimizing this out, since getauxval is
            just reading a field in the ELF header.
            */
            const unsigned long hwcap_crypto = ::getauxval(ARM_hwcap_bit::ARCH_hwcap_crypto);
            if (hwcap_crypto & ARM_hwcap_bit::AES_bit)
                detected_features |= cpuid::CPUID_ARM_RIJNDAEL_BIT;
            if (hwcap_crypto & ARM_hwcap_bit::PMULL_bit)
                detected_features |= cpuid::CPUID_ARM_PMULL_BIT;
            if (hwcap_crypto & ARM_hwcap_bit::SHA1_bit)
                detected_features |= cpuid::CPUID_ARM_SHA1_BIT;
            if (hwcap_crypto & ARM_hwcap_bit::SHA2_bit)
                detected_features |= cpuid::CPUID_ARM_SHA2_BIT;
 
#elif defined(CRYPTO3_TARGET_OS_IS_IOS)
 
            char machine[64] = {0};
            size_t size = sizeof(machine) - 1;
            ::sysctlbyname("hw.machine", machine, &size, nullptr, 0);
 
            detected_features = flags_by_ios_machine_type(machine);
 
#elif defined(CRYPTO3_USE_GCC_INLINE_ASM) && defined(CRYPTO3_TARGET_ARCHITECTURE_IS_ARM64)
 
            /*
            No getauxval API available, fall back on probe functions. We only
            bother with Aarch64 here to simplify the code and because going to
            extreme contortions to support detect NEON on devices that probably
            don't support it doesn't seem worthwhile.
 
            NEON registers v0-v7 are caller saved in Aarch64
            */
 
            auto neon_probe = []() -> int {
                asm("and v0.16b, v0.16b, v0.16b");
                return 1;
            };
            auto aes_probe = []() -> int {
                asm(".word 0x4e284800");
                return 1;
            };
            auto pmull_probe = []() -> int {
                asm(".word 0x0ee0e000");
                return 1;
            };
            auto sha1_probe = []() -> int {
                asm(".word 0x5e280800");
                return 1;
            };
            auto sha2_probe = []() -> int {
                asm(".word 0x5e282800");
                return 1;
            };
 
            // Only bother running the crypto3 detection if we found NEON
 
            if (run_cpu_instruction_probe(neon_probe) == 1) {
                detected_features |= cpuid::CPUID_ARM_NEON_BIT;
 
                if (run_cpu_instruction_probe(aes_probe) == 1)
                    detected_features |= cpuid::CPUID_ARM_RIJNDAEL_BIT;
                if (run_cpu_instruction_probe(pmull_probe) == 1)
                    detected_features |= cpuid::CPUID_ARM_PMULL_BIT;
                if (run_cpu_instruction_probe(sha1_probe) == 1)
                    detected_features |= cpuid::CPUID_ARM_SHA1_BIT;
                if (run_cpu_instruction_probe(sha2_probe) == 1)
                    detected_features |= cpuid::CPUID_ARM_SHA2_BIT;
            }
 
#endif
 
            return detected_features;
        }
 
#endif
    }    // namespace crypto3
}    // namespace nil