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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/cpu.h"
#include <string.h>
#include <algorithm>
#include "base/basictypes.h"
#include "build/build_config.h"
#if defined(ARCH_CPU_ARM_FAMILY) && (defined(OS_ANDROID) || defined(OS_LINUX))
#include "base/file_util.h"
#include "base/lazy_instance.h"
#endif
#if defined(ARCH_CPU_X86_FAMILY)
#if defined(_MSC_VER)
#include <intrin.h>
#include <immintrin.h> // For _xgetbv()
#endif
#endif
namespace base {
CPU::CPU()
: signature_(0),
type_(0),
family_(0),
model_(0),
stepping_(0),
ext_model_(0),
ext_family_(0),
has_mmx_(false),
has_sse_(false),
has_sse2_(false),
has_sse3_(false),
has_ssse3_(false),
has_sse41_(false),
has_sse42_(false),
has_avx_(false),
has_avx_hardware_(false),
has_aesni_(false),
has_non_stop_time_stamp_counter_(false),
cpu_vendor_("unknown") {
Initialize();
}
namespace {
#if defined(ARCH_CPU_X86_FAMILY)
#ifndef _MSC_VER
#if defined(__pic__) && defined(__i386__)
void __cpuid(int cpu_info[4], int info_type) {
__asm__ volatile (
"mov %%ebx, %%edi\n"
"cpuid\n"
"xchg %%edi, %%ebx\n"
: "=a"(cpu_info[0]), "=D"(cpu_info[1]), "=c"(cpu_info[2]), "=d"(cpu_info[3])
: "a"(info_type)
);
}
#else
void __cpuid(int cpu_info[4], int info_type) {
__asm__ volatile (
"cpuid \n\t"
: "=a"(cpu_info[0]), "=b"(cpu_info[1]), "=c"(cpu_info[2]), "=d"(cpu_info[3])
: "a"(info_type)
);
}
#endif
// _xgetbv returns the value of an Intel Extended Control Register (XCR).
// Currently only XCR0 is defined by Intel so |xcr| should always be zero.
uint64 _xgetbv(uint32 xcr) {
uint32 eax, edx;
__asm__ volatile ("xgetbv" : "=a" (eax), "=d" (edx) : "c" (xcr));
return (static_cast<uint64>(edx) << 32) | eax;
}
#endif // !_MSC_VER
#endif // ARCH_CPU_X86_FAMILY
#if defined(ARCH_CPU_ARM_FAMILY) && (defined(OS_ANDROID) || defined(OS_LINUX))
// Returns the string found in /proc/cpuinfo under the key "model name" or
// "Processor". "model name" is used in Linux 3.8 and later (3.7 and later for
// arm64) and is shown once per CPU. "Processor" is used in earler versions and
// is shown only once at the top of /proc/cpuinfo regardless of the number CPUs.
std::string ParseCpuInfo() {
const char kModelNamePrefix[] = "model name\t: ";
const char kProcessorPrefix[] = "Processor\t: ";
std::string contents;
ReadFileToString(FilePath("/proc/cpuinfo"), &contents);
DCHECK(!contents.empty());
std::string cpu_brand;
if (!contents.empty()) {
std::istringstream iss(contents);
std::string line;
while (std::getline(iss, line)) {
if (line.compare(0, strlen(kModelNamePrefix), kModelNamePrefix) == 0) {
cpu_brand.assign(line.substr(strlen(kModelNamePrefix)));
break;
}
if (line.compare(0, strlen(kProcessorPrefix), kProcessorPrefix) == 0) {
cpu_brand.assign(line.substr(strlen(kProcessorPrefix)));
break;
}
}
}
return cpu_brand;
}
class LazyCpuInfoValue {
public:
LazyCpuInfoValue() : value_(ParseCpuInfo()) {}
const std::string& value() { return value_; }
private:
const std::string value_;
DISALLOW_COPY_AND_ASSIGN(LazyCpuInfoValue);
};
base::LazyInstance<LazyCpuInfoValue> g_lazy_cpu_brand =
LAZY_INSTANCE_INITIALIZER;
const std::string& CpuBrandInfo() {
return g_lazy_cpu_brand.Get().value();
}
#endif // defined(ARCH_CPU_ARM_FAMILY) && (defined(OS_ANDROID) ||
// defined(OS_LINUX))
} // anonymous namespace
void CPU::Initialize() {
#if defined(ARCH_CPU_X86_FAMILY)
int cpu_info[4] = {-1};
char cpu_string[48];
// __cpuid with an InfoType argument of 0 returns the number of
// valid Ids in CPUInfo[0] and the CPU identification string in
// the other three array elements. The CPU identification string is
// not in linear order. The code below arranges the information
// in a human readable form. The human readable order is CPUInfo[1] |
// CPUInfo[3] | CPUInfo[2]. CPUInfo[2] and CPUInfo[3] are swapped
// before using memcpy to copy these three array elements to cpu_string.
__cpuid(cpu_info, 0);
int num_ids = cpu_info[0];
std::swap(cpu_info[2], cpu_info[3]);
memcpy(cpu_string, &cpu_info[1], 3 * sizeof(cpu_info[1]));
cpu_vendor_.assign(cpu_string, 3 * sizeof(cpu_info[1]));
// Interpret CPU feature information.
if (num_ids > 0) {
__cpuid(cpu_info, 1);
signature_ = cpu_info[0];
stepping_ = cpu_info[0] & 0xf;
model_ = ((cpu_info[0] >> 4) & 0xf) + ((cpu_info[0] >> 12) & 0xf0);
family_ = (cpu_info[0] >> 8) & 0xf;
type_ = (cpu_info[0] >> 12) & 0x3;
ext_model_ = (cpu_info[0] >> 16) & 0xf;
ext_family_ = (cpu_info[0] >> 20) & 0xff;
has_mmx_ = (cpu_info[3] & 0x00800000) != 0;
has_sse_ = (cpu_info[3] & 0x02000000) != 0;
has_sse2_ = (cpu_info[3] & 0x04000000) != 0;
has_sse3_ = (cpu_info[2] & 0x00000001) != 0;
has_ssse3_ = (cpu_info[2] & 0x00000200) != 0;
has_sse41_ = (cpu_info[2] & 0x00080000) != 0;
has_sse42_ = (cpu_info[2] & 0x00100000) != 0;
has_avx_hardware_ =
(cpu_info[2] & 0x10000000) != 0;
// AVX instructions will generate an illegal instruction exception unless
// a) they are supported by the CPU,
// b) XSAVE is supported by the CPU and
// c) XSAVE is enabled by the kernel.
// See http://software.intel.com/en-us/blogs/2011/04/14/is-avx-enabled
//
// In addition, we have observed some crashes with the xgetbv instruction
// even after following Intel's example code. (See crbug.com/375968.)
// Because of that, we also test the XSAVE bit because its description in
// the CPUID documentation suggests that it signals xgetbv support.
has_avx_ =
has_avx_hardware_ &&
(cpu_info[2] & 0x04000000) != 0 /* XSAVE */ &&
(cpu_info[2] & 0x08000000) != 0 /* OSXSAVE */ &&
(_xgetbv(0) & 6) == 6 /* XSAVE enabled by kernel */;
has_aesni_ = (cpu_info[2] & 0x02000000) != 0;
}
// Get the brand string of the cpu.
__cpuid(cpu_info, 0x80000000);
const int parameter_end = 0x80000004;
int max_parameter = cpu_info[0];
if (cpu_info[0] >= parameter_end) {
char* cpu_string_ptr = cpu_string;
for (int parameter = 0x80000002; parameter <= parameter_end &&
cpu_string_ptr < &cpu_string[sizeof(cpu_string)]; parameter++) {
__cpuid(cpu_info, parameter);
memcpy(cpu_string_ptr, cpu_info, sizeof(cpu_info));
cpu_string_ptr += sizeof(cpu_info);
}
cpu_brand_.assign(cpu_string, cpu_string_ptr - cpu_string);
}
const int parameter_containing_non_stop_time_stamp_counter = 0x80000007;
if (max_parameter >= parameter_containing_non_stop_time_stamp_counter) {
__cpuid(cpu_info, parameter_containing_non_stop_time_stamp_counter);
has_non_stop_time_stamp_counter_ = (cpu_info[3] & (1 << 8)) != 0;
}
#elif defined(ARCH_CPU_ARM_FAMILY) && (defined(OS_ANDROID) || defined(OS_LINUX))
cpu_brand_.assign(CpuBrandInfo());
#endif
}
CPU::IntelMicroArchitecture CPU::GetIntelMicroArchitecture() const {
if (has_avx()) return AVX;
if (has_sse42()) return SSE42;
if (has_sse41()) return SSE41;
if (has_ssse3()) return SSSE3;
if (has_sse3()) return SSE3;
if (has_sse2()) return SSE2;
if (has_sse()) return SSE;
return PENTIUM;
}
} // namespace base
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