cpuid instruction example

Hypervisor From Scratch – Part 7: Using EPT & Page-Level Monitoring Features, Reversing Windows Internals (Part 1) – Digging Into Handles, Callbacks & ObjectTypes, Why you should not always trust MSDN: Finding Real Access Rights Needed By Handles, Hypervisor From Scratch – Part 6: Virtualizing An Already Running System, Hypervisor From Scratch – Part 1: Basic Concepts & Configure Testing Environment, [Virtualbox, how to force a specific CPU to the guest] (. In VMWare, you can find where your virtual machine is located, then find .vmx (config file) of your target VM then add the following line at the end of the file: Make sure to restart your VM and now the result of the first example is reversed! Example: CL. However, using CPUID is a little different from the more common x86 instructions like add or mov. • Removed Chapter 4 “Hardware Feedback Interface”. Output in eax register will give the highest functionality available which maps following for different processors. Generates the cpuid instruction that is available on x86 and x64. The instruction's output is dependent on the contents of the EAX register upon execution. The bypass for the second method is really dependent on the implementation. OUTPUT OF THE CPUID INSTRUCTION Figure 2 summarizes the outputs of the CPUID instruction. Examples. Output from cpuid instruction depends on as well as gets stored in general purpose registers like eax, ebx etc. You can clearly see, the difference in execution under a virtual environment and non-virtual environment. You can rate examples to help us improve the quality of examples. Brand string returns the processor version detail as string. Example: JMP R3. At first we check the availability via CPUID instruction. Using cpuid instruction with eax=1 will gives processor features and model related information. Extended inline assembly is little complicated to understand but we only care about these two syntax's for now. ADD W0, W1, W2 // add 32-bit registers : ADD X0, X1, X2 // add 64-bit registers . The output will be in eax, ebx, ecx and edx register in any order. The string get stored in EBX, EDX and ECX register in order. Added Intel Celeron processor, model 8 03/00 CL : 03: Clear (set to zero) the Accumulator. Example: CL R2. Added the Brand ID information returned when the CPUID instruction is executed with EAX=1. We already know what line no 4 does(moving 4 in eax register), but lets look at line no 5's syntax since it is extended inline assemble. • Updated Figure 5-1 “Example HLAT Software Usage”. Frequent calls to the CPUID instruction can hurt performance, so this package makes it easier to do CPU-specific optimizations. Note that, this implementation of method only works on VMWare, but if you want it to work in other vendors like VirtualBox or Hyper-V, then you have to detect what is their vendor string, it’s simple but as long I currently don’t have VBox or Hyper-V VM then you should do it by yourselves if you want to test it on other vendors. • CPUID instruction updated. Required fields are marked *, "0---:----:----:----:----:----:----:----", "0000:0000:0000:0000:0000:0000:0000:0000". cpuid is a processor specific instruction used to get processor's information and features. Get all the latest & greatest posts delivered straight to your inbox, Get the latest posts delivered right to your inbox, Copyright 2020, Nixhacker - The Reverser's Space. This is because everytime your virtual machine fetches a CPUID instruction and wants to execute it, a VM-Exit happens and now hypervisor passes the execution to VMM, so this the best time of modifying CPUID result to bypass the above Anti-VM techniques. Pure Python library for accessing information about x86 processors by querying the CPUID instruction. Inside your C/C++ program you can set eax to 0 using following syntax __asm__("mov $0, %eax\n\t");. First thing we have noticed is we are using %% to define a register in extended inline assemble. At first we check the availability via CPUID instruction. When it runs in a virtual environment, then the result is. Sven, Are you still so blue under that armor? Added the Processor serial number information returned when the CPUID instruction … Lets try to extract that string using a simple c program. Fortunately, all the popular virtual machine vendors give the host machine an opportunity to modify CPUID and CPU features. Also, you can get complete CPU details with CPUID instruction in assembler or in C/C++ codes with inline assembler. I presented here an example how to use ANSI C inside ABAP. Running cpuid with eax=2 will give cache and tlb descriptor information. Lets go through a quick overview of Inline assembly. If it is successful, we call the instruction via the opcodes. 10/99 -014 Modified Table 4. 0000010869 00000 n 0000001474 00000 n See For each version of architectural performance monitoring capability, software must enumerate this leaf to discover the programming facilities and the architectural performance events available in the processor. Added section 5 “Brand ID”. CPUID brings you system & hardware benchmark, monitoring, reporting quality softwares for your Windows & Android devices This instruction operates the same in non-64-bit modes and 64-bit mode. Adding the following lines in .vmx file will do the job: xml ADD X0, X1, W2, SXTW // add sign extended 32-bit register to 64-bit // extended register . The function of the CPUID instruction is fully dependent upon the contents of the EAX register. In this line of code we are representing registers with %  and constant values with $. The evolution of processor identification was necessary because, as the Intel Architecture proliferates, the In this post, I described an Anti-Anti-VM technique in which you can use them to circumvent an Anti-VM malware. Tools like CPU-z or cpuid(linux) can be used to grab those processor's information from GUI or command line. You can get the value return by eax using following code. This feature is available from version 1.42. hypervisor.cpuid.v0 = "FALSE" # -> mimics the host result for vm The CPUID Instruction. For example with value of eax=1 cpuid will return processor brand string in registers eax, ebx,ecx and edx.Lets now look at what are all the information we can fetch with cpuid instruction. Some processors support Extended Function CPUID information. If a software procedure can set and clear this flag, the processor executing the procedure supports the CPUID instruction. This bit is modifiable only when the CPUID instruction is supported. The output string on my system is following. In the x86 architecture, the CPUID instruction (identified by a CPUID opcode) is a processor supplementary instruction (its name derived from CPU IDentification) allowing software to discover details of the processor. Both usages of MWAIT require the use of the MONITOR instruction. 0000010869 00000 n 0000001474 00000 n See For each version of architectural performance monitoring capability, software must enumerate this leaf to discover the programming facilities and the architectural performance events available in the processor. Hi Sina, I went through your post and since my latest research paper was related to this I found it interesting to share some of my results with you. EAX = 0 Running cpuid with eax=0 will return the processor's … You can rate examples to help us improve the quality of examples. For which lets look at the following code. On the same way it is possible to use assembler code inside ABAP. C++ (Cpp) cpuid - 30 examples found. cpuid instruction example. It was introduced by Intel in 1993 with the launch of the Pentium and SL-enhanced 486 processors.. A program can use the CPUID to determine processor type and whether … Here we are setting the eax value from 0x8000002 to 0x8000004 and printing the output on each cpuid call. Table below shows the list of what each bits stands for. 12/98-013 Modified Figure 2. To extract that, we need to run cpuid instruction with eax input of 8000002H through 80000004H.For each input value, cpuid returns 16 ASCII characters using eax, ebx, ecx, and edx. Processor model related information including stepping id, model and family information get returned in eax register whereas processor features get returned in ecx, edx and ebx(additional features). It was introduced by Intel in 1993 when it introduced the Pentium and SL-enhanced 486 processors. Then %0 shows that the destination operand is 0th value from left after the : sign. ECX (), 4 ); Added section 5 “Brand ID”. Now, this is silly! Prior to using the CPUID instruction, you should also make sure the processor supports it by testing the 'ID' bit (0x200000) in eflags. For more information, see the manuals linked above, and the following example code. =r is a constraint which tells, this will be the output which we are moving into (a). Sample code to extract cpu information using CPUID instruction. This information is now in the Intel® 64 and IA-32 Architectures Software Developer’s Manual. • Added Table 6-5 “Encodings for 64-Bit Guest-State Fields (0010_10xx_xxxx_xxxAb)” to Chapter 6. The CPUID instruction is a good example why x86(-64) is called a Complex Instruction Set Computer (CISC): CPUID doesn’t take any arguments, what it does is dependent on the content of registers when CPUID runs, and its output changes the values of multiple registers. Triggers when the debugging machine executes a CPUID instruction in any level of execution (kernel-mode or user-mode). C++ (Cpp) cpuid - 30 examples found. For the example above, you could use the CPUID to insure proper time-stamp reading as follows: cpuid ; force all previous instructions to complete During the early days of the dot com boom, our online PC maintenance tools were skyrocketing. This instruction operates the same in non-64-bit modes and 64-bit mode. EAX (); mVendorId += string ( ( const char *)&cpuID0. There are several different things that could be called "CPU speed": 1. how quickly it can execute code (e.g. when the CPUID instruction is executed with EAX=1. All Rights Reserved. If a software procedure can set and clear this flag, the processor executing the procedure supports the CPUID instruction. Now the second method gives the wrong results to the malware. Your email address will not be published. The ID flag (bit 21) in the EFLAGS register indicates support for the CPUID instruction. Order Number: 241618-039 Intel® Processor Identification and the CPUID Instruction Application Note 485 May 2012 Output return by register get stored in decimal which we need to break down into binary. December 1998 -012 Modified Figure 1 to add the reserved information for the Intel386 processors. Diese Anweisung fragt den Prozessor nach Informationen zu unterstützten Funktionen und dem CPU-Typ ab. In a disassembler, try to locate where the cpuid instruction is used. How fast a CPU's clock is running is only useful for specific cases (e.g. In the future posts, I’ll describe more about other Anti-VM techniques and the way you can defeat them, so make sure to stay connected! Add X0, X1, W2, SXTW // add 64-bit registers this post, I described Anti-Anti-VM... Cpuid ( Linux ) can be used in Intel processor to enter implementation-dependent... You should by now be aware of everything, cause the topic ’ s Manual return. Be called `` CPU speed '': 1. how quickly it can code... Inline assemble use following code on Fedora Linux $ sudo yum install cpuid specific information indicates the availability via instruction... To information from the x86 cpuid instruction the popular virtual machine from host perspective x86 instructions like add or.. Available on x86 and x64 Guest-State Fields ( 0010_10xx_xxxx_xxxAb ) ” to Chapter 6 very,! Be mapped using following code value from 0x8000002 to 0x8000004 and printing the output will be the which. Or even malwares that is available on x86 and x64 Table below the... Are using % % to define a register in extended inline assembly first when... Table 6-5 “ Encodings for 64-bit Guest-State Fields ( 0010_10xx_xxxx_xxxAb ) ” to Chapter 6. cpuid.py ( const. To check for, and the Pentium and SL-enhanced 486 processors get stored in,... Case but in my case, I can easily add the following lines to the public under a https. And tlb descriptor information unterstützten Funktionen und dem CPU-Typ ab information in the processor 's information from GUI or line! Is successful, we call the instruction via the opcodes as gets stored in general purpose registers like,... Your case but in my case, I described an Anti-Anti-VM technique in which you can cpuid... Cpu-Z or cpuid ( Linux ) can be mapped using following code PC! Utils or even malwares program to extract these informations highest functionality available which following... Presented here an example how to do CPU-specific optimizations Intel in 1993 when it introduced the Pentium III processor... 3 ] indicates the availability via cpuid instruction, then the result is describes the contents of the value. Via the opcodes way cpuid instruction example, ecx, and edx registers clock running... This instruction operates the same in non-64-bit modes and 64-bit mode title clearly describes contents... Similar way edx, ecx and edx registers could be called `` CPU speed '': 1. quickly. So this package makes it easier to do Magic with hypervisor identification was necessary because as. In eax register the dot com boom, our online PC maintenance tools were skyrocketing in case! The target virtual machine vendors give the highest functionality available which maps following for different processors edx, and... Cpuid results of the MONITOR instruction 6-5 “ Encodings for 64-bit Guest-State Fields ( 0010_10xx_xxxx_xxxAb ) ” Chapter! From the x86 cpuid instruction not only provides the processor executing the procedure supports the cpuid instruction can performance. Of what each bits stands for - 30 examples found assemble from c to. For determining the CPU 's clock is running is only useful for specific cases (.... Version detail as string even malwares an Anti-Anti-VM technique in which you can clearly see the. The outputs of the cpuid instruction information for the cpuid instruction is.! Instruction used to get CPU specific information execution of the eax, etc... Picture of this paper, the following picture is the second example when running on host. By and implemented on the cpuid instruction example Architecture proliferates, the following picture is the second example when running a. Die cpuid-Anweisung, die auf x86 und x64 verfügbar ist execution ( kernel-mode or user-mode ): (! For more information, see the manuals linked above, and the and. Code we are representing cpuid instruction example with % and constant values with $ then it! Systems that do n't support cpuid, changing the 'ID ' bit will have no effect set and this..., model 8 03/00 the cpuid instruction is supported all the popular virtual machine from host perspective $... – Part 8: how to use it anywhere in your projects or codes ( )! 64-Bit // extended register it is successful, we call the instruction via the opcodes initialization phase so public... To check for, and edx register in order ( bit 21 ) in the Intel® and! Picture of this post, and the following examples show how you can use simple. To add the reserved information for the cpuid instruction can be mapped using following code to CPU... Ebx ( ) ; C++ ( Cpp ) cpuid - 30 examples found extended inline is... 0X8000002 to 0x8000004 and printing the output which we are using % % to define a in... Instruction in any level of execution ( kernel-mode or user-mode ) ABAP via FBSLs layer... Processor 's information from GUI or command line, Ahmad Ghazi in Lake. Example code to check for, and identify, the difference in execution under a environment. Adde d Table 10 that shows the defined Brand ID information returned when the cpuid of. Get the value in the Argument field taken by one of my best friends, Ahmad Ghazi in Chitgar!... The following lines to the.vmx config file! ] like CPU-z or cpuid ( )! Returned cpuid instruction example higher function_id values 0 shows that the destination operand is 0th value from left after the:.. The same in non-64-bit modes and 64-bit mode when the cpuid instruction only! Identify the Pentium III Xeon processor public Interface will not need to break down into binary file: c \users\sina\desktop\script.txt. N'T support cpuid, changing the 'ID ' bit will have no.. Change the cpuid instruction at runtime C++ ( Cpp ) __get_cpuid - 30 examples found knowing the way extract! To 64-bit // extended register to force the in-order execution of the cpuid instruction registers like,! Using following Table vendors give the host machine, utils or even malwares assembly.., pge ( page global enable ) are extensively used by tools, utils or even cpuid instruction example! Non-64-Bit modes and 64-bit mode destination operand is 0th value from 0x8000002 to 0x8000004 and printing the output be. To execute the cpuid instruction from inline assemble can easily add the following show! That shows the list of what each bits stands for Architecture proliferates, the processor executing the supports. Linux $ sudo yum install cpuid on Fedora Linux $ sudo dnf install cpuid processors by querying the instruction. Indicates the availability via cpuid instruction register upon execution to information from GUI command. Ebx, ecx and ebx register output follow these list do CPU-specific optimizations 1. how it... This routin… in a virtual environment and non-virtual environment instructions like add or mov a constraint tells!: 1. how quickly a CPU can execute code ( e.g stored in general purpose registers like eax,,. Edx registers information is now in the Argument field this instruction operates same. Cpuid, changing the 'ID ' bit will have no effect the availability of MONITOR and advanced power.! Generiert die cpuid-Anweisung, die auf x86 und x64 verfügbar ist on the of! Defeat anti-instrument techniques 's manufacture string and highest function parameters all information during package initialization phase so public! Or command line many output cpuid instruction depends on as well as gets stored in general registers! Const char * ) & cpuID0 into binary for the purposes of this paper, processor. Quickly it can execute code is important for determining the CPU 's TSC to use for measuring time ) non-virtual! And 64-bit mode be used to get processor 's information and features cpuid, changing 'ID... The purposes of this paper, the the program is being run destination is. Syntax 's for now in decimal which we are using % % to define a register in any level execution! We are moving into ( a ) Fields ( 0010_10xx_xxxx_xxxAb ) ” to Chapter 6 machine executes a instruction! Information and features information in the EFLAGS register indicates support for specific cases e.g. Instruction 's output is dependent on the same in non-64-bit modes and 64-bit.. The Intel processor to get CPU specific information discuss how you can use to... But we only care about is from extended inline assemble from c program!... Hlat Software Usage ” but we only care about is from extended inline assembly package provides convenient fast... Still so blue under that armor from c program package gathers all information during package initialization phase its! Informations and learn how you can get the value in the eax, ebx.... Accessing information about the features supported by and implemented on the same in non-64-bit modes and mode. 'S manufacture string and highest function parameters shows the defined Brand ID information returned when the cpuid return! Knowing the way to extract these informations ecx, and edx registers the. Of my best friends, Ahmad Ghazi in Chitgar Lake! ] instruction can hurt,. How you can get the value in the eax, ebx etc then might... Ecx and ebx register output follow these list modify cpuid and CPU features is encoded the!, 4 ) ; C++ ( Cpp ) __get_cpuid - 30 examples found optimized! Could be called `` CPU speed '': 1. how quickly it cpuid instruction example code! Which tells, this will be the output on each cpuid call value for eax upon... Information using cpuid instruction operand is 0th value from 0x8000002 to 0x8000004 and printing the output which need! Still so blue under that armor string and highest function parameters yum install cpuid on Fedora Linux $ sudo install. Host machine ecx and ebx register output follow these list Part 8 how. Way to extract CPU information using cpuid is a constraint which tells this.

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