review request: 7184394: add intrinsics to use AES instructions
Vladimir Kozlov
vladimir.kozlov at oracle.com
Thu Jul 26 15:49:11 PDT 2012
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.
>>>>>
>>
>
>
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