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--- third_party/crc32c/src/src/crc32c_arm64_linux_check.h.orig 2019-04-05 02:55:11.000000000 +0200
+++ third_party/crc32c/src/src/crc32c_arm64_linux_check.h 2019-04-15 08:43:01.276910000 +0200
@@ -7,8 +7,6 @@
#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>
@@ -16,30 +14,19 @@
#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
-
+#include <machine/armreg.h>
+#include <sys/types.h>
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
-}
+ inline bool CanUseArm64Linux() {
+ uint64_t id_aa64isar0;
+
+ id_aa64isar0 = READ_SPECIALREG(ID_AA64ISAR0_EL1);
+ if ((ID_AA64ISAR0_AES(id_aa64isar0) == ID_AA64ISAR0_AES_PMULL) && \
+ (ID_AA64ISAR0_CRC32(id_aa64isar0) == ID_AA64ISAR0_CRC32_BASE))
+ return true;
+ return false;
+ }
} // namespace crc32c
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