[Bug 1601836] Re: Openssl libcrypto performance issue

[Launchpad Bug Tracker]

This bug was fixed in the package openssl - 1.0.2g-1ubuntu4.2

---------------
openssl (1.0.2g-1ubuntu4.2) xenial; urgency=medium

  * Cherry-pick s390x assembly pack bugfix to cache capability query
    results for improved performance. LP: #1601836.
  * Enable asm optimisations on s390x. LP: #1602655.

 -- Dimitri John Ledkov <xnox at ubuntu.com>  Thu, 28 Jul 2016 15:37:07
+0300

** Changed in: openssl (Ubuntu Xenial)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1601836

Title:
  Openssl libcrypto performance issue

Status in Ubuntu on IBM z Systems:
  Fix Committed
Status in openssl package in Ubuntu:
  Fix Released
Status in openssl source package in Xenial:
  Fix Released

Bug description:
  == Comment: #0 - Bastian Pfeifer <Bastian.Pfeifer at de.ibm.com> - 2016-04-22 03:37:03 ==
  ---Problem Description---
  Performance problem with s390x assembly code in the openssl libcrypto library:
  CPACF functions such as SHA, AES ... queries the CPACF facility bits too often.

  Problematic code can be found here:
  https://github.com/openssl/openssl/blob/master/crypto/sha/asm/sha1-s390x.pl

  What happens is that for every e.g SHA1 call the code first tests if
  the HW function is available. That's the case for all the CPACF
  functions.

  However what the lib should do is to query only once, safe the value
  and then use the function. The problem is that the Hipervisor in
  certain scenarios is required to intercept the query instructions,
  which makes this really expensive.

   
  Contact Information = Bastian.Pfeifer at de.ibm.com 
   
  ---uname output---
  4.4.0-18-generic #34-Ubuntu SMP 
   
  Machine Type = 2964, 701 NC9 
   
  ---Debugger---
  A debugger is not configured
   
  ---Steps to Reproduce---
   n/a
   
  Userspace tool common name: OpenSSL 
   
  The userspace tool has the following bit modes: 64-bit 

  Userspace rpm: OpenSSL 1.0.2g  1 Mar 2016

  Userspace tool obtained from project website:  na 
   
  *Additional Instructions for Bastian.Pfeifer at de.ibm.com:
  -Attach ltrace and strace of userspace application.

  == Comment: #8 - Bastian Pfeifer <Bastian.Pfeifer at de.ibm.com> - 2016-06-02 07:05:00 ==
  We performed tests on the new SHA,AES and GHASH code and report performance improvements especially for SHA (up to 20%).

  Here are the links to the new s390x assembly code which should be used
  to create patches for the UBUNTU specific openssl versions.

  1)
  https://github.com/openssl/openssl/blob/master/crypto/s390xcpuid.S
  2)
  https://github.com/openssl/openssl/blob/master/crypto/s390xcap.c
  3)
  https://github.com/openssl/openssl/blob/master/crypto/sha/asm/sha1-s390x.pl
  4)
  https://github.com/openssl/openssl/blob/master/crypto/sha/asm/sha512-s390x.pl
  5)
  https://github.com/openssl/openssl/blob/master/crypto/aes/asm/aes-s390x.pl
  6)
  https://github.com/openssl/openssl/blob/master/crypto/modes/asm/ghash-s390x.pl

  In case of AES I was forced to change the following code in aes-
  s390x.pl

  .globl	AES_set_decrypt_key
  .type	AES_set_decrypt_key,\@function

  goes to

  .globl	private_AES_set_decrypt_key
  .type	        private_AES_set_decrypt_key,\@function

  This was done for 'AES_set_encrypt_key as well; to be consistent with
  the openssl code which comes with UBUNTU. For my performance tests
  this worked properly and I checked the CPACF counter with the tool
  'cpacfstats'.

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