x86[_64]cpuid.pl: handle new extensions.
This commit is contained in:
@@ -2,7 +2,7 @@
|
||||
|
||||
=head1 NAME
|
||||
|
||||
OPENSSL_ia32cap - finding the IA-32 processor capabilities
|
||||
OPENSSL_ia32cap - the IA-32 processor capabilities vector
|
||||
|
||||
=head1 SYNOPSIS
|
||||
|
||||
@@ -18,30 +18,52 @@ input value (see Intel Application Note #241618). Naturally it's
|
||||
meaningful on x86 and x86_64 platforms only. The variable is normally
|
||||
set up automatically upon toolkit initialization, but can be
|
||||
manipulated afterwards to modify crypto library behaviour. For the
|
||||
moment of this writing seven bits are significant, namely:
|
||||
moment of this writing following bits are significant:
|
||||
|
||||
1. bit #4 denoting presence of Time-Stamp Counter.
|
||||
2. bit #20, reserved by Intel, is used to choose among RC4 code
|
||||
paths;
|
||||
3. bit #23 denoting MMX support;
|
||||
4. bit #25 denoting SSE support;
|
||||
5. bit #26 denoting SSE2 support;
|
||||
6. bit #28 denoting Hyperthreading, which is used to distiguish
|
||||
cores with shared cache;
|
||||
7. bit #30, reserved by Intel, is used to choose among RC4 code
|
||||
paths;
|
||||
8. bit #57 denoting Intel AES instruction set extension;
|
||||
=item bit #4 denoting presence of Time-Stamp Counter.
|
||||
|
||||
=item bit #19 denoting availability of CLFLUSH instruction;
|
||||
|
||||
=item bit #20, reserved by Intel, is used to choose among RC4 code paths;
|
||||
|
||||
=item bit #23 denoting MMX support;
|
||||
|
||||
=item bit #24, FXSR bit, denoting availability of XMM registers;
|
||||
|
||||
=item bit #25 denoting SSE support;
|
||||
|
||||
=item bit #26 denoting SSE2 support;
|
||||
|
||||
=item bit #28 denoting Hyperthreading, which is used to distiguish
|
||||
cores with shared cache;
|
||||
|
||||
=item bit #30, reserved by Intel, is used to choose among RC4 code
|
||||
paths;
|
||||
|
||||
=item bit #33 denoting availability of PCLMULQDQ instruction;
|
||||
|
||||
=item bit #41 denoting SSSE3, Supplemental SSE3, support;
|
||||
|
||||
=item bit #43 denoting AMD XOP support (forced to zero on Intel);
|
||||
|
||||
=item bit #57 denoting AES-NI instruction set extension;
|
||||
|
||||
=item bit #59, OSXSAVE bit, denoting availability of YMM registers;
|
||||
|
||||
=item bit #60 denoting AVX extension;
|
||||
|
||||
For example, clearing bit #26 at run-time disables high-performance
|
||||
SSE2 code present in the crypto library. You might have to do this if
|
||||
target OpenSSL application is executed on SSE2 capable CPU, but under
|
||||
control of OS which does not support SSE2 extentions. Even though you
|
||||
can manipulate the value programmatically, you most likely will find it
|
||||
more appropriate to set up an environment variable with the same name
|
||||
prior starting target application, e.g. on Intel P4 processor 'env
|
||||
OPENSSL_ia32cap=0x12900010 apps/openssl', to achieve same effect
|
||||
without modifying the application source code. Alternatively you can
|
||||
reconfigure the toolkit with no-sse2 option and recompile.
|
||||
SSE2 code present in the crypto library, while clearing bit #24
|
||||
disables SSE2 code operating on 128-bit XMM register bank. You might
|
||||
have to do the latter if target OpenSSL application is executed on SSE2
|
||||
capable CPU, but under control of OS that does not enable XMM
|
||||
registers. Even though you can manipulate the value programmatically,
|
||||
you most likely will find it more appropriate to set up an environment
|
||||
variable with the same name prior starting target application, e.g. on
|
||||
Intel P4 processor 'env OPENSSL_ia32cap=0x16980010 apps/openssl', to
|
||||
achieve same effect without modifying the application source code.
|
||||
Alternatively you can reconfigure the toolkit with no-sse2 option and
|
||||
recompile.
|
||||
|
||||
Less intuituve is clearing bit #28. The truth is that it's not copied
|
||||
from CPUID output verbatim, but is adjusted to reflect whether or not
|
||||
@@ -49,4 +71,3 @@ the data cache is actually shared between logical cores. This in turn
|
||||
affects the decision on whether or not expensive countermeasures
|
||||
against cache-timing attacks are applied, most notably in AES assembler
|
||||
module.
|
||||
=cut
|
||||
|
||||
Reference in New Issue
Block a user