checksum.cpp
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//===-- checksum.cpp --------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "checksum.h"
#include "atomic_helpers.h"
#if defined(__x86_64__) || defined(__i386__)
#include <cpuid.h>
#elif defined(__arm__) || defined(__aarch64__)
#if SCUDO_FUCHSIA
#include <zircon/features.h>
#include <zircon/syscalls.h>
#else
#include <sys/auxv.h>
#endif
#endif
namespace scudo {
Checksum HashAlgorithm = {Checksum::BSD};
#if defined(__x86_64__) || defined(__i386__)
// i386 and x86_64 specific code to detect CRC32 hardware support via CPUID.
// CRC32 requires the SSE 4.2 instruction set.
#ifndef bit_SSE4_2
#define bit_SSE4_2 bit_SSE42 // clang and gcc have different defines.
#endif
bool hasHardwareCRC32() {
u32 Eax, Ebx = 0, Ecx = 0, Edx = 0;
__get_cpuid(0, &Eax, &Ebx, &Ecx, &Edx);
const bool IsIntel = (Ebx == signature_INTEL_ebx) &&
(Edx == signature_INTEL_edx) &&
(Ecx == signature_INTEL_ecx);
const bool IsAMD = (Ebx == signature_AMD_ebx) && (Edx == signature_AMD_edx) &&
(Ecx == signature_AMD_ecx);
if (!IsIntel && !IsAMD)
return false;
__get_cpuid(1, &Eax, &Ebx, &Ecx, &Edx);
return !!(Ecx & bit_SSE4_2);
}
#elif defined(__arm__) || defined(__aarch64__)
#ifndef AT_HWCAP
#define AT_HWCAP 16
#endif
#ifndef HWCAP_CRC32
#define HWCAP_CRC32 (1U << 7) // HWCAP_CRC32 is missing on older platforms.
#endif
bool hasHardwareCRC32() {
#if SCUDO_FUCHSIA
u32 HWCap;
const zx_status_t Status =
zx_system_get_features(ZX_FEATURE_KIND_CPU, &HWCap);
if (Status != ZX_OK)
return false;
return !!(HWCap & ZX_ARM64_FEATURE_ISA_CRC32);
#else
return !!(getauxval(AT_HWCAP) & HWCAP_CRC32);
#endif // SCUDO_FUCHSIA
}
#else
// No hardware CRC32 implemented in Scudo for other architectures.
bool hasHardwareCRC32() { return false; }
#endif // defined(__x86_64__) || defined(__i386__)
} // namespace scudo