review request: add intrinsics to use AES instructions

[Deneau, Tom]

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.
>