text: // Copyright 2017 Google LLC
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //    http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License 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 "cpuinfo_arm.h"
  
  #include <assert.h>
  #include <ctype.h>
  
  #include "internal/bit_utils.h"
  #include "internal/filesystem.h"
  #include "internal/hwcaps.h"
  #include "internal/stack_line_reader.h"
  #include "internal/string_view.h"
  
  // Generation of feature's getters/setters functions and kGetters, kSetters,
  // kCpuInfoFlags and kHardwareCapabilities global tables.
  #define DEFINE_TABLE_FEATURES                                         \
    FEATURE(ARM_SWP, swp, "swp", ARM_HWCAP_SWP, 0)                      \
    FEATURE(ARM_HALF, half, "half", ARM_HWCAP_HALF, 0)                  \
    FEATURE(ARM_THUMB, thumb, "thumb", ARM_HWCAP_THUMB, 0)              \
    FEATURE(ARM_26BIT, _26bit, "26bit", ARM_HWCAP_26BIT, 0)             \
    FEATURE(ARM_FASTMULT, fastmult, "fastmult", ARM_HWCAP_FAST_MULT, 0) \
    FEATURE(ARM_FPA, fpa, "fpa", ARM_HWCAP_FPA, 0)                      \
    FEATURE(ARM_VFP, vfp, "vfp", ARM_HWCAP_VFP, 0)                      \
    FEATURE(ARM_EDSP, edsp, "edsp", ARM_HWCAP_EDSP, 0)                  \
    FEATURE(ARM_JAVA, java, "java", ARM_HWCAP_JAVA, 0)                  \
    FEATURE(ARM_IWMMXT, iwmmxt, "iwmmxt", ARM_HWCAP_IWMMXT, 0)          \
    FEATURE(ARM_CRUNCH, crunch, "crunch", ARM_HWCAP_CRUNCH, 0)          \
    FEATURE(ARM_THUMBEE, thumbee, "thumbee", ARM_HWCAP_THUMBEE, 0)      \
    FEATURE(ARM_NEON, neon, "neon", ARM_HWCAP_NEON, 0)                  \
    FEATURE(ARM_VFPV3, vfpv3, "vfpv3", ARM_HWCAP_VFPV3, 0)              \
    FEATURE(ARM_VFPV3D16, vfpv3d16, "vfpv3d16", ARM_HWCAP_VFPV3D16, 0)  \
    FEATURE(ARM_TLS, tls, "tls", ARM_HWCAP_TLS, 0)                      \
    FEATURE(ARM_VFPV4, vfpv4, "vfpv4", ARM_HWCAP_VFPV4, 0)              \
    FEATURE(ARM_IDIVA, idiva, "idiva", ARM_HWCAP_IDIVA, 0)              \
    FEATURE(ARM_IDIVT, idivt, "idivt", ARM_HWCAP_IDIVT, 0)              \
    FEATURE(ARM_VFPD32, vfpd32, "vfpd32", ARM_HWCAP_VFPD32, 0)          \
    FEATURE(ARM_LPAE, lpae, "lpae", ARM_HWCAP_LPAE, 0)                  \
    FEATURE(ARM_EVTSTRM, evtstrm, "evtstrm", ARM_HWCAP_EVTSTRM, 0)      \
    FEATURE(ARM_AES, aes, "aes", 0, ARM_HWCAP2_AES)                     \
    FEATURE(ARM_PMULL, pmull, "pmull", 0, ARM_HWCAP2_PMULL)             \
    FEATURE(ARM_SHA1, sha1, "sha1", 0, ARM_HWCAP2_SHA1)                 \
    FEATURE(ARM_SHA2, sha2, "sha2", 0, ARM_HWCAP2_SHA2)                 \
    FEATURE(ARM_CRC32, crc32, "crc32", 0, ARM_HWCAP2_CRC32)
  #define DEFINE_TABLE_FEATURE_TYPE ArmFeatures
  #include "define_tables.h"
  
  typedef struct {
    bool processor_reports_armv6;
    bool hardware_reports_goldfish;
  } ProcCpuInfoData;
  
  static int IndexOfNonDigit(StringView str) {
    size_t index = 0;
    while (str.size && isdigit(CpuFeatures_StringView_Front(str))) {
      str = CpuFeatures_StringView_PopFront(str, 1);
      ++index;
    }
    return index;
  }
  
  static bool HandleArmLine(const LineResult result, ArmInfo* const info,
                            ProcCpuInfoData* const proc_info) {
    StringView line = result.line;
    StringView key, value;
    if (CpuFeatures_StringView_GetAttributeKeyValue(line, &key, &value)) {
      if (CpuFeatures_StringView_IsEquals(key, str("Features"))) {
        for (size_t i = 0; i < ARM_LAST_; ++i) {
          kSetters[i](&info->features,
                      CpuFeatures_StringView_HasWord(value, kCpuInfoFlags[i]));
        }
      } else if (CpuFeatures_StringView_IsEquals(key, str("CPU implementer"))) {
        info->implementer = CpuFeatures_StringView_ParsePositiveNumber(value);
      } else if (CpuFeatures_StringView_IsEquals(key, str("CPU variant"))) {
        info->variant = CpuFeatures_StringView_ParsePositiveNumber(value);
      } else if (CpuFeatures_StringView_IsEquals(key, str("CPU part"))) {
        info->part = CpuFeatures_StringView_ParsePositiveNumber(value);
      } else if (CpuFeatures_StringView_IsEquals(key, str("CPU revision"))) {
        info->revision = CpuFeatures_StringView_ParsePositiveNumber(value);
      } else if (CpuFeatures_StringView_IsEquals(key, str("CPU architecture"))) {
        // CPU architecture is a number that may be followed by letters. e.g.
        // "6TEJ", "7".
        const StringView digits =
            CpuFeatures_StringView_KeepFront(value, IndexOfNonDigit(value));
        info->architecture = CpuFeatures_StringView_ParsePositiveNumber(digits);
      } else if (CpuFeatures_StringView_IsEquals(key, str("Processor")) ||
                 CpuFeatures_StringView_IsEquals(key, str("model name"))) {
        // Android reports this in a non-Linux standard "Processor" but sometimes
        // also in "model name", Linux reports it only in "model name"
        // see RaspberryPiZero (Linux) vs InvalidArmv7 (Android) test-cases
        proc_info->processor_reports_armv6 =
            CpuFeatures_StringView_IndexOf(value, str("(v6l)")) >= 0;
      } else if (CpuFeatures_StringView_IsEquals(key, str("Hardware"))) {
        proc_info->hardware_reports_goldfish =
            CpuFeatures_StringView_IsEquals(value, str("Goldfish"));
      }
    }
    return !result.eof;
  }
  
  uint32_t GetArmCpuId(const ArmInfo* const info) {
    return (ExtractBitRange(info->implementer, 7, 0) << 24) |
           (ExtractBitRange(info->variant, 3, 0) << 20) |
           (ExtractBitRange(info->part, 11, 0) << 4) |
           (ExtractBitRange(info->revision, 3, 0) << 0);
  }
  
  static void FixErrors(ArmInfo* const info,
                        ProcCpuInfoData* const proc_cpu_info_data) {
    // Fixing Samsung kernel reporting invalid cpu architecture.
    // http://code.google.com/p/android/issues/detail?id=10812
    if (proc_cpu_info_data->processor_reports_armv6 && info->architecture >= 7) {
      info->architecture = 6;
    }
  
    // Handle kernel configuration bugs that prevent the correct reporting of CPU
    // features.
    switch (GetArmCpuId(info)) {
      case 0x4100C080:
        // Special case: The emulator-specific Android 4.2 kernel fails to report
        // support for the 32-bit ARM IDIV instruction. Technically, this is a
        // feature of the virtual CPU implemented by the emulator. Note that it
        // could also support Thumb IDIV in the future, and this will have to be
        // slightly updated.
        if (info->architecture >= 7 &&
            proc_cpu_info_data->hardware_reports_goldfish) {
          info->features.idiva = true;
        }
        break;
      case 0x511004D0:
        // https://crbug.com/341598.
        info->features.neon = false;
        break;
      case 0x510006F2:
      case 0x510006F3:
        // The Nexus 4 (Qualcomm Krait) kernel configuration forgets to report
        // IDIV support.
        info->features.idiva = true;
        info->features.idivt = true;
        break;
    }
  
    // Propagate cpu features.
    if (info->features.vfpv4) info->features.vfpv3 = true;
    if (info->features.neon) info->features.vfpv3 = true;
    if (info->features.vfpv3) info->features.vfp = true;
  }
  
  static void FillProcCpuInfoData(ArmInfo* const info,
                                  ProcCpuInfoData* proc_cpu_info_data) {
    const int fd = CpuFeatures_OpenFile("/proc/cpuinfo");
    if (fd >= 0) {
      StackLineReader reader;
      StackLineReader_Initialize(&reader, fd);
      for (;;) {
        if (!HandleArmLine(StackLineReader_NextLine(&reader), info,
                           proc_cpu_info_data)) {
          break;
        }
      }
      CpuFeatures_CloseFile(fd);
    }
  }
  
  static const ArmInfo kEmptyArmInfo;
  
  static const ProcCpuInfoData kEmptyProcCpuInfoData;
  
  ArmInfo GetArmInfo(void) {
    // capabilities are fetched from both getauxval and /proc/cpuinfo so we can
    // have some information if the executable is sandboxed (aka no access to
    // /proc/cpuinfo).
    ArmInfo info = kEmptyArmInfo;
    ProcCpuInfoData proc_cpu_info_data = kEmptyProcCpuInfoData;
  
    FillProcCpuInfoData(&info, &proc_cpu_info_data);
    const HardwareCapabilities hwcaps = CpuFeatures_GetHardwareCapabilities();
    for (size_t i = 0; i < ARM_LAST_; ++i) {
      if (CpuFeatures_IsHwCapsSet(kHardwareCapabilities[i], hwcaps)) {
        kSetters[i](&info.features, true);
      }
    }
  
    FixErrors(&info, &proc_cpu_info_data);
  
    return info;
  }
  
  ////////////////////////////////////////////////////////////////////////////////
  // Introspection functions
  
  int GetArmFeaturesEnumValue(const ArmFeatures* features,
                              ArmFeaturesEnum value) {
    if (value >= ARM_LAST_) return false;
    return kGetters[value](features);
  }
  
  const char* GetArmFeaturesEnumName(ArmFeaturesEnum value) {
    if (value >= ARM_LAST_) return "unknown feature";
    return kCpuInfoFlags[value];
  }
  