#
# ====================================================================
# Written by Andy Polyakov <appro@fy.chalmers.se> for the OpenSSL
# project. The module is, however, dual licensed under OpenSSL and
# CRYPTOGAMS licenses depending on where you obtain it. For further
# details see http://www.openssl.org/~appro/cryptogams/.
# ====================================================================
#
# 2.22x RC4 tune-up:-) It should be noted though that my hand [as in
# "hand-coded assembler"] doesn't stand for the whole improvement
# coefficient. It turned out that eliminating RC4_CHAR from config
# line results in ~40% improvement (yes, even for C implementation).
# Presumably it has everything to do with AMD cache architecture and
# RAW or whatever penalties. Once again! The module *requires* config
# line *without* RC4_CHAR! As for coding "secret," I bet on partial
# register arithmetics. For example instead of 'inc %r8; and $255,%r8'
# I simply 'inc %r8b'. Even though optimization manual discourages
# to operate on partial registers, it turned out to be the best bet.
# At least for AMD... How IA32E would perform remains to be seen...
# As was shown by Marc Bevand reordering of couple of load operations
# results in even higher performance gain of 3.3x:-) At least on
# Opteron... For reference, 1x in this case is RC4_CHAR C-code
# compiled with gcc 3.3.2, which performs at ~54MBps per 1GHz clock.
# Latter means that if you want to *estimate* what to expect from
# *your* Opteron, then multiply 54 by 3.3 and clock frequency in GHz.
# Intel P4 EM64T core was found to run the AMD64 code really slow...
# The only way to achieve comparable performance on P4 was to keep
# RC4_CHAR. Kind of ironic, huh? As it's apparently impossible to
# compose blended code, which would perform even within 30% marginal
# on either AMD and Intel platforms, I implement both cases. See
# rc4_skey.c for further details...
# loop...
# As was shown by Zou Nanhai loop unrolling can improve Intel EM64T
# performance by >30% [unlike P4 32-bit case that is]. But this is
# provided that loads are reordered even more aggressively! Both code
# pathes, AMD64 and EM64T, reorder loads in essentially same manner
# as my IA-64 implementation. On Opteron this resulted in modest 5%
# improvement [I had to test it], while final Intel P4 performance
# achieves respectful 432MBps on 2.8GHz processor now. For reference.
# If executed on Xeon, current RC4_CHAR code-path is 2.7x faster than
# RC4_INT code-path. While if executed on Opteron, it's only 25%
# slower than the RC4_INT one [meaning that if CPU �-arch detection
# is not implemented, then this final RC4_CHAR code-path should be
# preferred, as it provides better *all-round* performance].
# Intel Core2 was observed to perform poorly on both code paths:-( It
# apparently suffers from some kind of partial register stall, which
# occurs in 64-bit mode only [as virtually identical 32-bit loop was
# observed to outperform 64-bit one by almost 50%]. Adding two movzb to
# cloop1 boosts its performance by 80%! This loop appears to be optimal
# fit for Core2 and therefore the code was modified to skip cloop8 on
# this CPU.
#
# OpenSolaris OS modifications
#
# Sun elects to use this software under the BSD license.
#
# This source originates from OpenSSL file rc4-x86_64.pl at
# (presumably for future OpenSSL release 0.9.8h), with these changes:
#
# 1. Added some comments, "use strict", and declared all variables.
#
# /usr/include/sys/asm_linkage.h.
#
# 3. Changed function name from RC4() to arcfour_crypt_asm() and RC4_set_key()
# to arcfour_key_init(), and changed the parameter order for both to that
# used by OpenSolaris.
#
# 4. The current method of using cpuid feature bits 20 (NX) or 28 (HTT) from
# some newer AMD64 processors, as these bits are set on both Intel EM64T
# processors and newer AMD64 processors. I replaced this with C code
# (function arcfour_crypt_on_intel()) to call cpuid_getvendor()
# when executing in the kernel and getisax() when executing in userland.
#
# 5. Set a new field in the key structure, key->flag to 0 for AMD AMD64
# and 1 for Intel EM64T. This is to select the most-efficient arcfour_crypt()
# function to use.
#
# 6. Removed x86_64-xlate.pl script (not needed for as(1) or gas(1) assemblers).
#
# 7. Removed unused RC4_CHAR, Lcloop1, and Lcloop8 code.
#
# 8. Added C function definitions for use by lint(1B).
#
use strict;
my $output = shift;
open STDOUT,">$output";
#
# Parameters
#
# OpenSSL:
# void RC4(RC4_KEY *key, unsigned long len, const unsigned char *indata,
# unsigned char *outdata);
#$dat="%rdi"; # arg1
#$len="%rsi"; # arg2
#$inp="%rdx"; # arg3
#$out="%rcx"; # arg4
# OpenSolaris:
# void arcfour_crypt_asm(ARCFour_key *key, uchar_t *in, uchar_t *out,
# size_t len);
#
# Register variables
#
# $XX[0] is key->i (aka key->x), $XX[1] is a temporary.
# $TX[0] and $TX[1] are temporaries.
# $YY is key->j (aka key->y).
# $TY is a temporary.
#
$YY="%r12";
$TY="%r13";
#if defined(lint) || defined(__lint)
#include "arcfour.h"
/* ARGSUSED */
{}
/* ARGSUSED */
{}
#else
#include <sys/asm_linkage.h>
.Lentry:
push %r12
push %r13
/
/
.align 16
.Lloop8:
for ($i=0;$i<8;$i++) {
}
sub \$8,$len
cmp \$0,$len
.Lexit:
/
/
pop %r13
pop %r12
.align 16
.Lloop1:
#
# Parameters
#
# OpenSSL:
# void RC4_set_key(RC4_KEY *key, int len, const unsigned char *data);
#$dat="%rdi"; # arg1
#$len="%rsi"; # arg2
#$inp="%rdx"; # arg3
# OpenSolaris:
# void arcfour_key_init(ARCFour_key *key, uchar_t *keyval, int keyvallen);
# Temporaries
$idx="%r8";
$ido="%r9";
/ int arcfour_crypt_on_intel(void);
.align 16
.align 16
.asciz "RC4 for x86_64, CRYPTOGAMS by <appro\@openssl.org>"
#endif /* !lint && !__lint */
$code =~ s/#([bwd])/$1/gm;
print $code;
close STDOUT;