review request: 7184394: add intrinsics to use AES instructions

Vladimir Kozlov vladimir.kozlov at oracle.com
Fri Jul 27 12:54:03 PDT 2012


This looks good.

Thanks,
Vladimir

Deneau, Tom wrote:
> http://cr.openjdk.java.net/~tdeneau/aes-intrinsics/webrev.04
> 
> has been posted which addresses the issues that Vladimir raised.
> 
> Not sure why webrev.sh was including files that had no changes, I just
> removed them from the index.html
> 
> -- Tom
> 
> -----Original Message-----
> From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com] 
> Sent: Thursday, July 26, 2012 5:49 PM
> To: Deneau, Tom
> Cc: hotspot-compiler-dev at openjdk.java.net
> Subject: Re: review request: 7184394: add intrinsics to use AES instructions
> 
> I only glanced on changed, I will look more on stubs code later.
> 
> Use VM_Version::supports_aes() instead of UseAES in asserts in Assembler::aes*() 
> methods.
> 
> I see dependency on AVX in stubGenerator_x86_*.cpp but I don't see UseAVX check 
> for UseAESIntrinsics flag setting. Also you should check UseAESIntrinsics flag 
> instead in this code:
> 
> +    // don't bother generating these AES intrinsic stubs unless AES support in 
> processor
> +    // note that these also require AVX mode for misaligned SSE access
> +    if (UseAES && (UseAVX > 0)) {
> 
> 
> Changes are empty in systemDictionary.hpp, compile.cpp and c2_globals.hpp files.
> 
> 
> Few comments about codding style:
> 
> Use one line accessors definition as other methods in stubRoutines_*.hpp:
> 
> +  static address aescrypt_encryptBlock()
> +  {
> +    return _aescrypt_encryptBlock;
> +  }
> 
> Use one line " } else {" in stubGenerator_x86_*.cpp:
> 
> +    }
> +    else {
> 
> Thanks,
> Vladimir
> 
> Deneau, Tom wrote:
>> I have submitted
>> http://cr.openjdk.java.net/~tdeneau/aes-intrinsics/webrev.03
>>
>> which
>>
>>    * incorporates some feedback from Vladimir regarding  the
>>      global flags I was using
>>
>>    * corrects some misunderstanding on my part about xmm register
>>      saving requirements on 32-bit windows.
>>
>> -- Tom
>>
>> -----Original Message-----
>> From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com] 
>> Sent: Thursday, July 19, 2012 6:07 PM
>> To: Deneau, Tom
>> Cc: hotspot-compiler-dev at openjdk.java.net
>> Subject: Re: review request: add intrinsics to use AES instructions
>>
>> I will ask my colleagues to look on this changes.
>>
>> Thanks,
>> Vladimir
>>
>> Deneau, Tom wrote:
>>> The 32-bit stubs have been added, the new webrev is at
>>> http://cr.openjdk.java.net/~tdeneau/aes-intrinsics/webrev.02  
>>>
>>> The stubGenerator files were basically the only changes.
>>>
>>> While adding the 32-bit stubs, I noticed that the 64-bit stubs
>>> could be cleaned up quite a bit, I used symbolic names rather
>>> than raw names for registers, etc.
>>>
>>> -- Tom
>>>
>>>
>>> -----Original Message-----
>>> From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com] 
>>> Sent: Monday, July 16, 2012 6:14 PM
>>> To: Deneau, Tom
>>> Cc: hotspot-compiler-dev at openjdk.java.net
>>> Subject: Re: review request: add intrinsics to use AES instructions
>>>
>>> Deneau, Tom wrote:
>>>> Vladimir --
>>>>
>>>> OK I see now that the stubroutines_x86_xxx are bitness-dependent.
>>>> And are you saying that you would prefer that the intrinsics actually
>>>> be supported on 32-bit, not just that it builds and runs without support on 32-bit?
>>> Yes, please, add the support on 32-bit (when AES is present). The stubs code 
>>> should be the same except incoming arguments.
>>>
>>> Vladimir
>>>
>>>> -- Tom
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com] 
>>>> Sent: Monday, July 16, 2012 2:08 PM
>>>> To: Deneau, Tom
>>>> Cc: hotspot-compiler-dev at openjdk.java.net
>>>> Subject: Re: review request: add intrinsics to use AES instructions
>>>>
>>>> You can't execute 32bit VM with missing 32bit changes because flags are set but 
>>>> stubs are missing. And, yes, 32 bit VM is still used.
>>>>
>>>> Vladimir
>>>>
>>>> Deneau, Tom wrote:
>>>>> Vladimir --
>>>>>
>>>>> Right I didn't include 32-bit changes thinking that the majority
>>>>> of users of AES encryption/decryption would be 64-bit servers.
>>>>>
>>>>> But there is no technical reason why 32-bit couldn't be added.
>>>>> Do you feel 32-bit support is important?
>>>>>
>>>>> -- Tom
>>>>>
>>>>>
>>>>>
>>>>> -----Original Message-----
>>>>> From: Vladimir Kozlov [mailto:vladimir.kozlov at oracle.com] 
>>>>> Sent: Monday, July 16, 2012 12:40 PM
>>>>> To: Deneau, Tom
>>>>> Cc: hotspot-compiler-dev at openjdk.java.net
>>>>> Subject: Re: review request: add intrinsics to use AES instructions
>>>>>
>>>>> Thank you, Tom
>>>>>
>>>>> I created next RFE and will sponsor changes. But I don't see 32 bit changes.
>>>>>
>>>>> 7184394: add intrinsics to use AES instructions
>>>>>
>>>>> Vladimir
>>>>>
>>>>> Deneau, Tom wrote:
>>>>>> Please review the following webrev which adds intrinsic support to
>>>>>> allow some of the com/sun/crypto/provider methods to use AES
>>>>>> instructions when a processor supports such instructions.
>>>>>>
>>>>>> http://cr.openjdk.java.net/~tdeneau/aes-intrinsics/webrev.01/
>>>>>>
>>>>>> I do not have a bug number for this change but a description would be
>>>>>> something like the following:
>>>>>>
>>>>>>    Modern x86 processors have AES instructions to accelerate AES
>>>>>>    encryption and decryption but Hotspot does not have a way to
>>>>>>    generate such instructions. There is a way to hook in a native
>>>>>>    crypto library using PKCS11 and there are a few native libraries
>>>>>>    that support hardware AES instructions. However, these native
>>>>>>    PKCS11 libraries
>>>>>>
>>>>>>       * do not scale well with multiple threads
>>>>>>       * are not supported on all platforms, for instance Hotspot does
>>>>>>         not have PKCS11 support on 64-bit Windows.
>>>>>>       * can be confusing to configure. 
>>>>>>
>>>>>> Since this webrev adds intrinsic support for the default
>>>>>> com/sun/crypto/provider classes, they are supported on all platforms
>>>>>> and there is no additional configuration required. Measurements have
>>>>>> shown that they scale very well will multiple threads.
>>>>>>
>>>>>> The rest of this mail describes the scope of the intrinsics and
>>>>>> summarizes the source file changes.
>>>>>>
>>>>>> -- Tom Deneau
>>>>>>
>>>>>> Scope of the Intrinsics
>>>>>> -----------------------
>>>>>> When creating a cipher the application specifies a "transformation"
>>>>>> consisting of "algorithm/mode/padding". For more details see
>>>>>> http://docs.oracle.com/javase/7/docs/api/javax/crypto/Cipher.html
>>>>>>
>>>>>>    * These intrinsics kick in only when the algorithm part is "AES". A
>>>>>>      single block in AES is always 16 bytes and there are intrinsics
>>>>>>      for encrypting or decrypting a single block. These single-block
>>>>>>      intrinsics can work with any mode that uses AES and with any of
>>>>>>      the three AES key sizes (128, 192 or 256 bit).
>>>>>>
>>>>>>    * A more optimized multi-block intrinsic can kick in if the
>>>>>>      algorithm/mode is "AES/CBC" (Cipher Block Chaining). Again all
>>>>>>      three AES key sizes are supported. There is no technical reason
>>>>>>      why we couldn't do multi-block intrinsics for the other modes
>>>>>>      (eg, ECB) but I want to get some feedback from the reviewers on
>>>>>>      the implementation before charging off on this path.
>>>>>>
>>>>>>    * The padding part is handled by java routines outside of these
>>>>>>      intrinsics.
>>>>>>
>>>>>> Summary of Changes
>>>>>> ------------------
>>>>>> src/cpu/x86/vm/assembler_x86.cpp, hpp
>>>>>>    Defined the aes instructions which are used by the stub routines.
>>>>>>
>>>>>> src/cpu/x86/vm/stubGenerator_x86_64.cpp,
>>>>>>    Actual stub code for the aes intrinsics. As described earlier there
>>>>>>    are both single-block and multi-block intrinsic stubs.
>>>>>>
>>>>>>    Note that the stubs make use of the "expanded key" which gets
>>>>>>    created each time the key changes. The expanded key is used by both
>>>>>>    the java code and the intrinsic AES instructions.
>>>>>>
>>>>>>    The java code stores the "expanded key" in big-endian 32-bit
>>>>>>    integers. The x86 AES instructions require the expanded key to be
>>>>>>    in little-endian 128-bit words. Hence the pshufb instructions to
>>>>>>    get the key into the little-endian format
>>>>>>
>>>>>> src/cpu/x86/vm/vm_version_x86.cpp, hpp
>>>>>>    Detect and store the aes capability bit in cpuid. A global boolean
>>>>>>    command line flag UseAES can be used to turn off AES even if the
>>>>>>    hardware supports it.
>>>>>>
>>>>>> src/share/vm/classfile/vmSymbols.hpp
>>>>>> src/share/vm/opto/runtime.cpp, hpp
>>>>>>    The usual definitions of class names, method names and signatures
>>>>>>    for the java methods that are being intrinsified and the signatures
>>>>>>    for the stubs
>>>>>>
>>>>>> src/share/vm/oops/methodOop.cpp
>>>>>>    Up until now, every intrinsic was replacing a routine that was
>>>>>>    loaded by the "default" (NULL) class  loader.
>>>>>>    com/sun/crypto/provider is not loaded by the default class
>>>>>>    loader so we had to add a check here.
>>>>>>
>>>>>> src/share/vm/opto/escape.cpp
>>>>>>    escape analysis knows about certain stubs, but if it sees a leaf
>>>>>>    stub it also checks against a predefined list. So the new intrinsic
>>>>>>    names were added to the list.
>>>>>>
>>>>>> src/share/vm/opto/library_call.cpp
>>>>>> src/share/vm/opto/callGenerator.cpp
>>>>>> src/share/vm/opto/doCall.cpp
>>>>>>
>>>>>>    The main logic for building up the calls to the stubs at compile
>>>>>>    time, assuming the platform has a stub and the global flags have
>>>>>>    not turned these intrinsics off.
>>>>>>
>>>>>>    A new helper routine to load a field from an object was added since
>>>>>>    we ended up loading fields in a few places.
>>>>>>
>>>>>>    For best performance, we wanted to hook into the multi-block
>>>>>>    encrypt and decrypt methods such as in CipherBlockChaining.java.
>>>>>>    This code is not AES-specific but handles CBC mode for any
>>>>>>    algorithm. (The algorithm part is handled by the enclosed
>>>>>>    "embeddedCipher" object).
>>>>>>
>>>>>>    Thus at runtime we want to do the equivalent of an instanceof check
>>>>>>    on embeddedCipher and either call the stub (if it is AESCrypt) or
>>>>>>    call the original java code (if it is some other algorithm
>>>>>>    type). For the CipherBlockChaining.decrypt there is a further
>>>>>>    runtime check that the source and destination are not the same
>>>>>>    array which, because of the way CBC works would require cloning the
>>>>>>    source (cipher).
>>>>>>
>>>>>>    Vladimir added some infrastructure to generate predicated
>>>>>>    intrinsics to solve the above problem. A particular intrinsic need
>>>>>>    only specify that it is predicated, and generate the particular
>>>>>>    guard node which if false will take the Java path. This
>>>>>>    infrastructure can be used for future intrinsics that have to make
>>>>>>    such a runtime choice. These changes from Vladimir are in
>>>>>>    callGenerator.cpp, doCall.cpp, and a small bit in library_call.cpp.
>>>>>>
>>>>>> src/share/vm/runtime/globals.hpp
>>>>>>    global flags were added to
>>>>>>       * turn off either AES encryption or AES decryption intrinsics separately
>>>>>>       * turn off the multi-block CBC/AES intrinsics. 
>>>>>>
>>>>>>    By default all of the above are on. These are really there for
>>>>>>    testing, for example one could encrypt using Java and decrypt using
>>>>>>    the intrinsics.
>>>>>>
>>>>>>    Also, a UseAES flag to ignore the hardware capability as described above.
>>>>>>
>>
> 
> 


More information about the hotspot-compiler-dev mailing list