cpuinfo.c File Reference

#include <ntoskrnl.h>
#include <x86x64/Cpuid.h>
#include <debug.h>

Include dependency graph for cpuinfo.c:

Go to the source code of this file.

Macros
#define	NDEBUG

Functions
VOID NTAPI	KiGetCpuVendorString (_Out_writes_z_(CPU_VENDOR_STR_LEN) CHAR VendorString[CPU_VENDOR_STR_LEN])
	Get the CPUID information for a given CPU.
CPU_VENDORS NTAPI	KiIdentifyCpuVendor (_In_reads_z_(CPU_VENDOR_STR_LEN) const CHAR VendorString[CPU_VENDOR_STR_LEN])
	Identify the CPU vendor by the vendor string.
VOID NTAPI	KiGetCpuSignature (_Out_ PUSHORT Family, _Out_ PUSHORT Model, _Out_ PUSHORT Stepping)
	Get the CPU signature.

Macro Definition Documentation

NDEBUG

#define NDEBUG

Definition at line 12 of file cpuinfo.c.

Function Documentation

KiGetCpuSignature()

VOID NTAPI KiGetCpuSignature	(	_Out_ PUSHORT	Family,
		_Out_ PUSHORT	Model,
		_Out_ PUSHORT	Stepping
	)

Get the CPU signature.

Parameters

[out]	Family	- Pointer to a USHORT to receive the family
[out]	Model	- Pointer to a USHORT to receive the model
[out]	Stepping	- Pointer to a USHORT to receive the stepping

\See

• https://www.sandpile.org/x86/cpuid.htm#level_0000_0001h
• https://github.com/InstLatx64/InstLatx64
• Intel:
  • https://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-vol-2a-manual.pdf#G5.876260
  • https://www.scss.tcd.ie/Jeremy.Jones/CS4021/processor-identification-cpuid-instruction-note.pdf
  • https://web.archive.org/web/20250907014024/https://en.wikichip.org/wiki/intel/cpuid
• AMD:
  • https://docs.amd.com/v/u/en-US/24594_3.37 (Appendix E)
  • https://ia803100.us.archive.org/29/items/advancedmicrodevices_24594_3.28/24594.pdf
  • https://kib.kiev.ua/x86docs/AMD/AMD-CPUID-Spec/20734-r3.13.pdf
  • https://web.archive.org/web/20251208232456/https://en.wikichip.org/wiki/amd/cpuid
• Cyrix:
  • http://bitsavers.computerhistory.org/components/cyrix/appnotes/Cyrix_CPU_Detection_Guide_1997.pdf

Definition at line 118 of file cpuinfo.c.

{
    CPUID_VERSION_INFO_REGS VersionInfo;
 
    /* Get the CPUID */
    __cpuid(VersionInfo.AsInt32, 1);
 
    /* Get the family */
    *Family = VersionInfo.Eax.Bits.FamilyId;
    if (VersionInfo.Eax.Bits.FamilyId == 15)
    {
        *Family += VersionInfo.Eax.Bits.ExtendedFamilyId;
    }
 
    /* Get the model */
    *Model = VersionInfo.Eax.Bits.Model;
    if ((VersionInfo.Eax.Bits.FamilyId == 6) ||
        (VersionInfo.Eax.Bits.FamilyId == 15))
    {
        /* For Family < 15, AMD documents extended model as RAZ (reads as zero) */
        *Model |= VersionInfo.Eax.Bits.ExtendedModelId << 4;
    }
 
    /* Get the stepping */
    *Stepping = VersionInfo.Eax.Bits.SteppingId;
}

Referenced by KiSetProcessorType().

KiGetCpuVendorString()

VOID NTAPI KiGetCpuVendorString

(

_Out_writes_z_(CPU_VENDOR_STR_LEN) CHAR

VendorString[CPU_VENDOR_STR_LEN]

)

Get the CPUID information for a given CPU.

Parameters

[out]

VendorString

- Pointer to a buffer to receive the vendor string

Definition at line 24 of file cpuinfo.c.

{
    CPUID_SIGNATURE_REGS Signature;
 
    /* Get the Vendor string */
    __cpuid(&Signature.AsInt32[0], CPUID_SIGNATURE);
 
    /* Copy and null-terminate it */
    *(ULONG*)&VendorString[0] = *(ULONG*)&Signature.SignatureScrambled[0];
    *(ULONG*)&VendorString[4] = *(ULONG*)&Signature.SignatureScrambled[8];
    *(ULONG*)&VendorString[8] = *(ULONG*)&Signature.SignatureScrambled[4];
    VendorString[12] = 0;
}

Referenced by KiSetProcessorType().

KiIdentifyCpuVendor()

CPU_VENDORS NTAPI KiIdentifyCpuVendor

(

_In_reads_z_(CPU_VENDOR_STR_LEN) const CHAR

VendorString[CPU_VENDOR_STR_LEN]

)

Identify the CPU vendor by the vendor string.

Parameters

[in]

VendorString

- Pointer to a buffer containing the vendor string

Returns

The CPU_VENDOR enum value that corresponds to the vendor string

See also

• https://en.wikipedia.org/wiki/CPUID
• https://github.com/InstLatx64/InstLatx64

Remarks

This function is called very early during the boot process, before the kernel debugger is initialized, so it must not do any debug prints.

Definition at line 55 of file cpuinfo.c.

{
    /* Identify the CPU vendor */
    if (!strcmp(VendorString, "GenuineIntel") ||
        !strcmp(VendorString, "GenuineIotel")) // Intel Xeon E3-1231 v3
    {
        return CPU_INTEL;
    }
    else if (!strcmp(VendorString, "AuthenticAMD") ||
             !strcmp(VendorString, "HygonGenuine"))
    {
        return CPU_AMD;
    }
    else if (!strcmp(VendorString, "CentaurHauls") ||
             !strcmp(VendorString, "  Shanghai  "))
    {
        return CPU_VIA; // == CPU_CENTAUR
    }
#ifdef _M_I386
    else if (!strcmp(VendorString, "CyrixInstead"))
    {
        return CPU_CYRIX;
    }
    else if (!strcmp(VendorString, "GenuineTMx86"))
    {
        return CPU_TRANSMETA;
    }
    else if (!strcmp(VendorString, "RiseRiseRise"))
    {
        return CPU_RISE;
    }
#endif // _M_I386
 
    return CPU_UNKNOWN;
}

Referenced by KiGetCpuVendor(), and KiSetProcessorType().