[Bug 1674399] Re: OpenSSL CPU detection for AMD Ryzen CPUs

[Eric Desrochers]

Debian bug :
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=861145


** Bug watch added: Debian Bug tracker #861145
   http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=861145

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Title:
  OpenSSL CPU detection for AMD Ryzen CPUs

Status in openssl package in Ubuntu:
  In Progress
Status in openssl source package in Xenial:
  Triaged
Status in openssl source package in Zesty:
  Triaged
Status in openssl source package in Artful:
  In Progress

Bug description:
  * Context

  AMD added support in their processors for SHA Extensions[1] (CPU flag:
  sha_ni[2]) starting with Ryzen[3] CPU. Note that Ryzen CPU come in
  64bit only (Confirmed with AMD representative). Current OpenSSL
  version in Ryzens still calls SHA for SSSE3 routine as result a number
  of extensions were effectively masked on Ryzen and shows no
  improvement.

  [1] /proc/cpuinfo
  processor	: 0
  vendor_id	: AuthenticAMD
  cpu family	: 23
  model		: 1
  model name	: AMD Ryzen 5 1600 Six-Core Processor
  flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc extd_apicid aperfmperf eagerfpu pni pclmulqdq monitor ssse3 fma cx16 sse
  4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_l2 mwaitx hw_pstate vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflusho
  pt sha_ni xsaveopt xsavec xgetbv1 clzero arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold

  [2] - sha_ni: SHA1/SHA256 Instruction Extensions

  [3] - https://en.wikipedia.org/wiki/Ryzen
  ...
  All models support: x87, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AES, CLMUL, AVX, AVX2, FMA, CVT16/F16C, ABM, BMI1, BMI2, SHA.[5]
  ...

  * Program to performs the CPUID check

  Reference :
  https://software.intel.com/en-us/articles/intel-sha-extensions

  ... Availability of the Intel® SHA Extensions on a particular
  processor can be determined by checking the SHA CPUID bit in
  CPUID.(EAX=07H, ECX=0):EBX.SHA [bit 29]. The following C function,
  using inline assembly, performs the CPUID check:

  --
  int CheckForIntelShaExtensions() {
     int a, b, c, d;

     // Look for CPUID.7.0.EBX[29]
     // EAX = 7, ECX = 0
     a = 7;
     c = 0;

     asm volatile ("cpuid"
          :"=a"(a), "=b"(b), "=c"(c), "=d"(d)
          :"a"(a), "c"(c)
         );

     // Intel® SHA Extensions feature bit is EBX[29]
     return ((b >> 29) & 1);
  }
  --

  On CPU with sha_ni the program return "1". Otherwise it return "0".

  * Upstream work:

  - Repository : https://github.com/openssl/openssl.git

  - Commits :
  1aed5e1 crypto/x86*cpuid.pl: move extended feature detection.
  ## This fix moves extended feature detection past basic feature detection where it belongs.

  f8418d8 crypto/x86_64cpuid.pl: move extended feature detection upwards.
  ## This commit for x86_64cpuid.pl addressed the problem, but messed up processor vendor detection.

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