[openssl-dev] [openssl.org #4509] ECC key generation under valgrind reports: impossible has happened

[Nikos Mavrogiannopoulos]

On Wed, 2016-04-27 at 14:38 +0000, Andy Polyakov via RT wrote:
> > 
> > > 
> > > > 
> > > > Valgrind does not necessarily support all instructions, if
> > > > there’s
> > > > any optimized assembly, you might run into problems.
> > > > Are you able to compile a non-assembly version of the OpenSSL
> > > > library?
> > > > Are you able to update to a newer Valgrind?
> > > Or at least tell valgrind version, because I can't reproduce the
> > > problem
> > > with 3.10.1. At any event you can also see if it's problem with
> > > unsupported instructions, unsupported by [your version of]
> > > valgrind
> > > that
> > > is, by manipulating OPENSSL_ia32cap environment variable. You can
> > > disable AVX2 code paths by setting it to :~0x20 or simply :0 if
> > > it
> > > runs into more "too-new-to-be-possible" instructions.
> > I tried with valgrind-3.11.0.
> Tough break... One can actually wonder if valgrind tampers with
> processor capability vector... And it totally does! I.e. even though
> my
> processor is AVX2-capable, when executed under my valgrind openssl
> doesn't see it as AVX2-capable. I suppose your valgrind passed AVX2
> flag, but failed to recognize all the instructions it should have...

I believe that's the case too. The same tests succeed without valgrind
on the same CPU.

regards,
Nikos