review request: add intrinsics to use AES instructions

Vladimir Kozlov vladimir.kozlov at
Mon Jul 16 16:13:57 PDT 2012

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.


> -- Tom
> -----Original Message-----
> From: Vladimir Kozlov [mailto:vladimir.kozlov at] 
> Sent: Monday, July 16, 2012 2:08 PM
> To: Deneau, Tom
> Cc: hotspot-compiler-dev at
> 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] 
>> Sent: Monday, July 16, 2012 12:40 PM
>> To: Deneau, Tom
>> Cc: hotspot-compiler-dev at
>> 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.
>>> 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
>>>    * 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
>>>    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.

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