1 files changed, 48 insertions, 0 deletions
diff --git a/third_party/crc32c/src/src/crc32c_arm64_linux_check.h b/third_party/crc32c/src/src/crc32c_arm64_linux_check.h
new file mode 100644
index 0000000000..6817979aac
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+++ b/third_party/crc32c/src/src/crc32c_arm64_linux_check.h
@@ -0,0 +1,48 @@
+// Copyright 2017 The CRC32C Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+// ARM Linux-specific code checking for the availability of CRC32C instructions.
+
+#ifndef CRC32C_CRC32C_ARM_LINUX_CHECK_H_
+#define CRC32C_CRC32C_ARM_LINUX_CHECK_H_
+
+// X86-specific code checking for the availability of SSE4.2 instructions.
+
+#include <cstddef>
+#include <cstdint>
+
+#include "crc32c/crc32c_config.h"
+
+#if HAVE_ARM64_CRC32C
+
+#if HAVE_STRONG_GETAUXVAL
+#include <sys/auxv.h>
+#elif HAVE_WEAK_GETAUXVAL
+// getauxval() is not available on Android until API level 20. Link it as a weak
+// symbol.
+extern "C" unsigned long getauxval(unsigned long type) __attribute__((weak));
+
+#define AT_HWCAP 16
+#endif  // HAVE_STRONG_GETAUXVAL || HAVE_WEAK_GETAUXVAL
+
+namespace crc32c {
+
+inline bool CanUseArm64Linux() {
+#if HAVE_STRONG_GETAUXVAL || HAVE_WEAK_GETAUXVAL
+  // From 'arch/arm64/include/uapi/asm/hwcap.h' in Linux kernel source code.
+  constexpr unsigned long kHWCAP_PMULL = 1 << 4;
+  constexpr unsigned long kHWCAP_CRC32 = 1 << 7;
+  unsigned long hwcap = (&getauxval != nullptr) ? getauxval(AT_HWCAP) : 0;
+  return (hwcap & (kHWCAP_PMULL | kHWCAP_CRC32)) ==
+         (kHWCAP_PMULL | kHWCAP_CRC32);
+#else
+  return false;
+#endif  // HAVE_STRONG_GETAUXVAL || HAVE_WEAK_GETAUXVAL
+}
+
+}  // namespace crc32c
+
+#endif  // HAVE_ARM64_CRC32C
+
+#endif  // CRC32C_CRC32C_ARM_LINUX_CHECK_H_