Merge pull request #10876 from shuffle2/cpudetect

CPUDetect: improve win/arm64 support

1 files changed, 248 insertions, 66 deletions

diff --git a/Source/Core/Common/ArmCPUDetect.cpp b/Source/Core/Common/ArmCPUDetect.cpp
index a12deac71a..7fe2d14220 100644
--- a/Source/Core/Common/ArmCPUDetect.cpp
+++ b/Source/Core/Common/ArmCPUDetect.cpp
@@ -9,45 +9,209 @@
 #include <string>
 #include <thread>
 
-#if !defined(_WIN32) && !defined(__APPLE__)
+#ifdef __APPLE__
+#include <sys/sysctl.h>
+#elif defined(_WIN32)
+#include <Windows.h>
+#include <arm64intr.h>
+#else
 #ifndef __FreeBSD__
 #include <asm/hwcap.h>
 #endif
 #include <sys/auxv.h>
-#include <unistd.h>
 #endif
 
 #include <fmt/format.h>
 
 #include "Common/CommonTypes.h"
 #include "Common/FileUtil.h"
+#include "Common/StringUtil.h"
+
+#if defined(__APPLE__) || defined(__FreeBSD__)
+
+static bool SysctlByName(std::string* value, const std::string& name)
+{
+  size_t value_len = 0;
+  if (sysctlbyname(name.c_str(), nullptr, &value_len, nullptr, 0))
+    return false;
 
-#ifndef WIN32
+  value->resize(value_len);
+  if (sysctlbyname(name.c_str(), value->data(), &value_len, nullptr, 0))
+    return false;
 
-const char procfile[] = "/proc/cpuinfo";
+  TruncateToCString(value);
+  return true;
+}
+
+#endif
 
-static std::string GetCPUString()
+#if defined(_WIN32)
+
+static constexpr char SUBKEY_CORE0[] = R"(HARDWARE\DESCRIPTION\System\CentralProcessor\0)";
+
+// Identifier: human-readable version of CPUID
+// ProcessorNameString: marketing name of the processor
+// VendorIdentifier: vendor company name
+// There are some other maybe-interesting values nearby, BIOS info etc.
+static bool ReadProcessorString(std::string* value, const std::string& name)
 {
-  const std::string marker = "Hardware\t: ";
-  std::string cpu_string = "Unknown";
+  const DWORD flags = RRF_RT_REG_SZ | RRF_NOEXPAND;
+  DWORD value_len = 0;
+  auto status = RegGetValueA(HKEY_LOCAL_MACHINE, SUBKEY_CORE0, name.c_str(), flags, nullptr,
+                             nullptr, &value_len);
+  if (status != ERROR_SUCCESS && status != ERROR_MORE_DATA)
+    return false;
 
-  std::string line;
+  value->resize(value_len);
+  status = RegGetValueA(HKEY_LOCAL_MACHINE, SUBKEY_CORE0, name.c_str(), flags, nullptr,
+                        value->data(), &value_len);
+  if (status != ERROR_SUCCESS)
+  {
+    value->clear();
+    return false;
+  }
+
+  TruncateToCString(value);
+  return true;
+}
+
+// Read cached register values from the registry
+static bool ReadPrivilegedCPReg(u64* value, u32 reg)
+{
+  DWORD value_len = sizeof(*value);
+  // Not sure if the value name is padded or not
+  return RegGetValueA(HKEY_LOCAL_MACHINE, SUBKEY_CORE0, fmt::format("CP {:x}", reg).c_str(),
+                      RRF_RT_REG_QWORD, nullptr, value, &value_len) == ERROR_SUCCESS;
+}
+
+static bool Read_MIDR_EL1(u64* value)
+{
+  return ReadPrivilegedCPReg(value, ARM64_SYSREG(0b11, 0, 0, 0b0000, 0));
+}
+
+static bool Read_ID_AA64ISAR0_EL1(u64* value)
+{
+  return ReadPrivilegedCPReg(value, ARM64_SYSREG(0b11, 0, 0, 0b0110, 0));
+}
+
+static bool Read_ID_AA64MMFR1_EL1(u64* value)
+{
+  return ReadPrivilegedCPReg(value, ARM64_SYSREG(0b11, 0, 0, 0b0111, 1));
+}
+
+#endif
+
+#if defined(__linux__)
+
+static bool ReadDeviceTree(std::string* value, const std::string& name)
+{
+  const std::string path = std::string("/proc/device-tree/") + name;
   std::ifstream file;
-  File::OpenFStream(file, procfile, std::ios_base::in);
+  File::OpenFStream(file, path.c_str(), std::ios_base::in);
+  if (!file)
+    return false;
 
+  file >> *value;
+  return true;
+}
+
+static std::string ReadCpuinfoField(const std::string& field)
+{
+  std::string line;
+  std::ifstream file;
+  File::OpenFStream(file, "/proc/cpuinfo", std::ios_base::in);
   if (!file)
-    return cpu_string;
+    return {};
 
   while (std::getline(file, line))
   {
-    if (line.find(marker) != std::string::npos)
-    {
-      cpu_string = line.substr(marker.length());
-      break;
-    }
+    if (!StringBeginsWith(line, field))
+      continue;
+    auto non_tab = line.find_first_not_of("\t", field.length());
+    if (non_tab == line.npos)
+      continue;
+    if (line[non_tab] != ':')
+      continue;
+    auto value_start = line.find_first_not_of(" ", non_tab + 1);
+    if (value_start == line.npos)
+      continue;
+    return line.substr(value_start);
   }
+  return {};
+}
 
-  return cpu_string;
+static bool Read_MIDR_EL1_Sysfs(u64* value)
+{
+  std::ifstream file;
+  File::OpenFStream(file, "/sys/devices/system/cpu/cpu0/regs/identification/midr_el1",
+                    std::ios_base::in);
+  if (!file)
+    return false;
+
+  file >> std::hex >> *value;
+  return true;
+}
+
+#endif
+
+#if defined(__linux__) || defined(__FreeBSD__)
+
+static u32 ReadHwCap(u32 type)
+{
+#if defined(__linux__)
+  return getauxval(type);
+#elif defined(__FreeBSD__)
+  u_long hwcap = 0;
+  elf_aux_info(type, &hwcap, sizeof(hwcap));
+  return hwcap;
+#endif
+}
+
+// For "Direct" reads, value gets filled via emulation, hence:
+// "there is no guarantee that the value reflects the processor that it is currently executing on"
+// On big.LITTLE systems, the value may be unrelated to the core this is invoked on, and unless
+// other measures are taken, executing the instruction may cause the caller to be switched onto a
+// different core when it resumes (and of course, caller could be preempted at any other time as
+// well).
+static inline u64 Read_MIDR_EL1_Direct()
+{
+  u64 value;
+  __asm__ __volatile__("mrs %0, MIDR_EL1" : "=r"(value));
+  return value;
+}
+
+static bool Read_MIDR_EL1(u64* value)
+{
+#ifdef __linux__
+  if (Read_MIDR_EL1_Sysfs(value))
+    return true;
+#endif
+
+  bool id_reg_user_access = ReadHwCap(AT_HWCAP) & HWCAP_CPUID;
+#ifdef __FreeBSD__
+  // FreeBSD kernel has support but doesn't seem to indicate it?
+  // see user_mrs_handler
+  id_reg_user_access = true;
+#endif
+  if (!id_reg_user_access)
+    return false;
+  *value = Read_MIDR_EL1_Direct();
+  return true;
+}
+
+#endif
+
+#ifndef __APPLE__
+
+static std::string MIDRToString(u64 midr)
+{
+  u8 implementer = (midr >> 24) & 0xff;
+  u8 variant = (midr >> 20) & 0xf;
+  u8 arch = (midr >> 16) & 0xf;
+  u16 part_num = (midr >> 4) & 0xfff;
+  u8 revision = midr & 0xf;
+  return fmt::format("{:02X}:{:X}:{:04b}:{:03X}:{:X}", implementer, variant, arch, part_num,
+                     revision);
 }
 
 #endif
@@ -59,82 +223,100 @@ CPUInfo::CPUInfo()
   Detect();
 }
 
-// Detects the various CPU features
 void CPUInfo::Detect()
 {
-  // Set some defaults here
-  HTT = false;
-  OS64bit = true;
-  CPU64bit = true;
-  Mode64bit = true;
   vendor = CPUVendor::ARM;
   bFMA = true;
   bFlushToZero = true;
-  bAFP = false;
+
+  num_cores = std::max(static_cast<int>(std::thread::hardware_concurrency()), 1);
 
 #ifdef __APPLE__
-  num_cores = std::thread::hardware_concurrency();
+  SysctlByName(&model_name, "machdep.cpu.brand_string");
 
   // M-series CPUs have all of these
-  bFP = true;
-  bASIMD = true;
+  // Apparently the world has accepted that these can be assumed supported "for all time".
+  // see https://github.com/golang/go/issues/42747
   bAES = true;
   bSHA1 = true;
   bSHA2 = true;
   bCRC32 = true;
 #elif defined(_WIN32)
-  num_cores = std::thread::hardware_concurrency();
-
-  // Windows does not provide any mechanism for querying the system registers on ARMv8, unlike Linux
-  // which traps the register reads and emulates them in the kernel. There are environment variables
-  // containing some of the CPU-specific values, which we could use for a lookup table in the
-  // future. For now, assume all features are present as all known devices which are Windows-on-ARM
-  // compatible also support these extensions.
-  bFP = true;
-  bASIMD = true;
-  bAES = true;
-  bCRC32 = true;
-  bSHA1 = true;
-  bSHA2 = true;
-#else
-  // Get the information about the CPU
-  num_cores = sysconf(_SC_NPROCESSORS_CONF);
-  strncpy(cpu_string, GetCPUString().c_str(), sizeof(cpu_string));
+  // NOTE All this info is from cpu core 0 only.
 
-#ifdef __FreeBSD__
-  u_long hwcaps = 0;
-  elf_aux_info(AT_HWCAP, &hwcaps, sizeof(u_long));
+  ReadProcessorString(&model_name, "ProcessorNameString");
+
+  u64 reg = 0;
+  // Attempt to be forward-compatible: perform inverted check against disabled feature states.
+  if (Read_ID_AA64ISAR0_EL1(&reg))
+  {
+    bAES = ((reg >> 4) & 0xf) != 0;
+    bSHA1 = ((reg >> 8) & 0xf) != 0;
+    bSHA2 = ((reg >> 12) & 0xf) != 0;
+    bCRC32 = ((reg >> 16) & 0xf) != 0;
+  }
+  if (Read_ID_AA64MMFR1_EL1(&reg))
+  {
+    // Introduced in Armv8.7, where AFP must be supported if AdvSIMD and FP both are.
+    bAFP = ((reg >> 44) & 0xf) != 0;
+  }
+  // Pre-decoded MIDR_EL1 could be read with ReadProcessorString(.., "Identifier"),
+  // but we want format to match across all platforms where possible.
+  if (Read_MIDR_EL1(&reg))
+  {
+    cpu_id = MIDRToString(reg);
+  }
 #else
-  unsigned long hwcaps = getauxval(AT_HWCAP);
+  // Linux, Android, and FreeBSD
+
+#if defined(__FreeBSD__)
+  SysctlByName(&model_name, "hw.model");
+#elif defined(__linux__)
+  if (!ReadDeviceTree(&model_name, "model"))
+  {
+    // This doesn't seem to work on modern arm64 kernels
+    model_name = ReadCpuinfoField("Hardware");
+  }
 #endif
-  bFP = hwcaps & HWCAP_FP;
-  bASIMD = hwcaps & HWCAP_ASIMD;
-  bAES = hwcaps & HWCAP_AES;
-  bCRC32 = hwcaps & HWCAP_CRC32;
-  bSHA1 = hwcaps & HWCAP_SHA1;
-  bSHA2 = hwcaps & HWCAP_SHA2;
+
+  const u32 hwcap = ReadHwCap(AT_HWCAP);
+  bAES = hwcap & HWCAP_AES;
+  bCRC32 = hwcap & HWCAP_CRC32;
+  bSHA1 = hwcap & HWCAP_SHA1;
+  bSHA2 = hwcap & HWCAP_SHA2;
+
+#if defined(AT_HWCAP2) && defined(HWCAP2_AFP)
+  const u32 hwcap2 = ReadHwCap(AT_HWCAP2);
+  bAFP = hwcap2 & HWCAP2_AFP;
 #endif
+
+  u64 midr = 0;
+  if (Read_MIDR_EL1(&midr))
+  {
+    cpu_id = MIDRToString(midr);
+  }
+#endif
+
+  model_name = ReplaceAll(model_name, ",", "_");
+  cpu_id = ReplaceAll(cpu_id, ",", "_");
 }
 
-// Turn the CPU info into a string we can show
 std::string CPUInfo::Summarize()
 {
-  std::string sum;
-  if (num_cores == 1)
-    sum = fmt::format("{}, 1 core", cpu_string);
-  else
-    sum = fmt::format("{}, {} cores", cpu_string, num_cores);
+  std::vector<std::string> sum;
+  sum.push_back(model_name);
+  sum.push_back(cpu_id);
 
+  if (bAFP)
+    sum.push_back("AFP");
   if (bAES)
-    sum += ", AES";
+    sum.push_back("AES");
   if (bCRC32)
-    sum += ", CRC32";
+    sum.push_back("CRC32");
   if (bSHA1)
-    sum += ", SHA1";
+    sum.push_back("SHA1");
   if (bSHA2)
-    sum += ", SHA2";
-  if (CPU64bit)
-    sum += ", 64-bit";
+    sum.push_back("SHA2");
 
-  return sum;
+  return JoinStrings(sum, ",");
 }