#!/usr/bin/env perl
# Ascetic x86_64 AT&T to MASM assembler translator by <appro>.
#
# Why AT&T to MASM and not vice versa? Several reasons. Because AT&T
# format is way easier to parse. Because it's simpler to "gear" from
# Unix ABI to Windows one [see cross-reference "card" at the end of
# file]. Because Linux targets were available first...
#
# In addition the script also "distills" code suitable for GNU
# assembler, so that it can be compiled with more rigid assemblers,
# such as Solaris /usr/ccs/bin/as.
#
# This translator is not designed to convert *arbitrary* assembler
# code from AT&T format to MASM one. It's designed to convert just
# enough to provide for dual-ABI OpenSSL modules development...
# There *are* limitations and you might have to modify your assembler
# code or this script to achieve the desired result...
#
# Currently recognized limitations:
#
# - can't use multiple ops per line;
# - indirect calls and jumps are not supported;
#
# Dual-ABI styling rules.
#
# 1. Adhere to Unix register and stack layout [see the end for
# explanation].
# 2. Forget about "red zone," stick to more traditional blended
# stack frame allocation. If volatile storage is actually required
# that is. If not, just leave the stack as is.
# 3. Functions tagged with ".type name,@function" get crafted with
# unified Win64 prologue and epilogue automatically. If you want
# to take care of ABI differences yourself, tag functions as
# ".type name,@abi-omnipotent" instead.
# 4. To optimize the Win64 prologue you can specify number of input
# arguments as ".type name,@function,N." Keep in mind that if N is
# larger than 6, then you *have to* write "abi-omnipotent" code,
# because >6 cases can't be addressed with unified prologue.
# 5. Name local labels as .L*, do *not* use dynamic labels such as 1:
# (sorry about latter).
# 6. Don't use [or hand-code with .byte] "rep ret." "ret" mnemonic is
# required to identify the spots, where to inject Win64 epilogue!
# But on the pros, it's then prefixed with rep automatically:-)
# 7. Due to MASM limitations [and certain general counter-intuitivity
# of ip-relative addressing] generation of position-independent
# code is assisted by synthetic directive, .picmeup, which puts
# address of the *next* instruction into target register.
#
# Example 1:
# .picmeup %rax
# lea .Label-.(%rax),%rax
# Example 2:
# .picmeup %rcx
# .Lpic_point:
# ...
# lea .Label-.Lpic_point(%rcx),%rbp
my $output = shift;
open STDOUT,">$output" || die "can't open $output: $!";
my $masm=1 if ($output =~ /\.asm/);
my $current_segment;
my $current_function;
{ package opcode; # pick up opcodes
sub re {
my $self = shift; # single instance in enough...
local *line = shift;
undef $ret;
if ($line =~ /^([a-z]+)/i) {
$self->{op} = $1;
$ret = $self;
$line = substr($line,@+[0]); $line =~ s/^\s+//;
undef $self->{sz};
if ($self->{op} =~ /(movz)b.*/) { # movz is pain...
$self->{op} = $1;
$self->{sz} = "b";
} elsif ($self->{op} =~ /([a-z]{3,})([qlwb])/) {
$self->{op} = $1;
$self->{sz} = $2;
}
}
$ret;
}
sub size {
my $self = shift;
my $sz = shift;
$self->{sz} = $sz if (defined($sz) && !defined($self->{sz}));
$self->{sz};
}
sub out {
my $self = shift;
if (!$masm) {
if ($self->{op} eq "movz") { # movz in pain...
sprintf "%s%s%s",$self->{op},$self->{sz},shift;
} elsif ($self->{op} eq "ret") {
".byte 0xf3,0xc3";
} else {
"$self->{op}$self->{sz}";
}
} else {
$self->{op} =~ s/movz/movzx/;
if ($self->{op} eq "ret") {
$self->{op} = "";
if ($current_function->{abi} eq "svr4") {
$self->{op} = "mov rdi,QWORD PTR 8[rsp]\t;WIN64 epilogue\n\t".
"mov rsi,QWORD PTR 16[rsp]\n\t";
}
$self->{op} .= "DB\t0F3h,0C3h\t\t;repret";
}
$self->{op};
}
}
}
{ package const; # pick up constants, which start with $
sub re {
my $self = shift; # single instance in enough...
local *line = shift;
undef $ret;
if ($line =~ /^\$([^,]+)/) {
$self->{value} = $1;
$ret = $self;
$line = substr($line,@+[0]); $line =~ s/^\s+//;
}
$ret;
}
sub out {
my $self = shift;
if (!$masm) {
sprintf "\$%s",$self->{value};
} else {
$self->{value} =~ s/0x([0-9a-f]+)/0$1h/ig;
sprintf "%s",$self->{value};
}
}
}
{ package ea; # pick up effective addresses: expr(%reg,%reg,scale)
sub re {
my $self = shift; # single instance in enough...
local *line = shift;
undef $ret;
if ($line =~ /^([^\(,]*)\(([%\w,]+)\)/) {
$self->{label} = $1;
($self->{base},$self->{index},$self->{scale})=split(/,/,$2);
$self->{scale} = 1 if (!defined($self->{scale}));
$ret = $self;
$line = substr($line,@+[0]); $line =~ s/^\s+//;
$self->{base} =~ s/^%//;
$self->{index} =~ s/^%// if (defined($self->{index}));
}
$ret;
}
sub size {}
sub out {
my $self = shift;
my $sz = shift;
if (!$masm) {
# elder GNU assembler insists on 64-bit EAs:-(
# on pros side, this results in more compact code:-)
$self->{index} =~ s/^[er](.?[0-9xp])[d]?$/r\1/;
$self->{base} =~ s/^[er](.?[0-9xp])[d]?$/r\1/;
# Solaris /usr/ccs/bin/as can't handle multiplications
# in $self->{label}
$self->{label} =~ s/(?<![0-9a-f])(0[x0-9a-f]+)/oct($1)/eg;
$self->{label} =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg;
if (defined($self->{index})) {
sprintf "%s(%%%s,%%%s,%d)",
$self->{label},$self->{base},
$self->{index},$self->{scale};
} else {
sprintf "%s(%%%s)", $self->{label},$self->{base};
}
} else {
%szmap = ( b=>"BYTE", w=>"WORD", l=>"DWORD", q=>"QWORD" );
$self->{label} =~ s/\./\$/g;
$self->{label} =~ s/0x([0-9a-f]+)/0$1h/ig;
$self->{label} = "($self->{label})" if ($self->{label} =~ /[\*\+\-\/]/);
if (defined($self->{index})) {
sprintf "%s PTR %s[%s*%d+%s]",$szmap{$sz},
$self->{label},
$self->{index},$self->{scale},
$self->{base};
} else {
sprintf "%s PTR %s[%s]",$szmap{$sz},
$self->{label},$self->{base};
}
}
}
}
{ package register; # pick up registers, which start with %.
sub re {
my $class = shift; # muliple instances...
my $self = {};
local *line = shift;
undef $ret;
if ($line =~ /^%(\w+)/) {
bless $self,$class;
$self->{value} = $1;
$ret = $self;
$line = substr($line,@+[0]); $line =~ s/^\s+//;
}
$ret;
}
sub size {
my $self = shift;
undef $ret;
if ($self->{value} =~ /^r[\d]+b$/i) { $ret="b"; }
elsif ($self->{value} =~ /^r[\d]+w$/i) { $ret="w"; }
elsif ($self->{value} =~ /^r[\d]+d$/i) { $ret="l"; }
elsif ($self->{value} =~ /^r[\w]+$/i) { $ret="q"; }
elsif ($self->{value} =~ /^[a-d][hl]$/i){ $ret="b"; }
elsif ($self->{value} =~ /^[\w]{2}l$/i) { $ret="b"; }
elsif ($self->{value} =~ /^[\w]{2}$/i) { $ret="w"; }
elsif ($self->{value} =~ /^e[a-z]{2}$/i){ $ret="l"; }
$ret;
}
sub out {
my $self = shift;
sprintf $masm?"%s":"%%%s",$self->{value};
}
}
{ package label; # pick up labels, which end with :
sub re {
my $self = shift; # single instance is enough...
local *line = shift;
undef $ret;
if ($line =~ /(^[\.\w]+\:)/) {
$self->{value} = $1;
$ret = $self;
$line = substr($line,@+[0]); $line =~ s/^\s+//;
$self->{value} =~ s/\.L/\$L/ if ($masm);
}
$ret;
}
sub out {
my $self = shift;
if (!$masm) {
$self->{value};
} elsif ($self->{value} ne "$current_function->{name}:") {
$self->{value};
} elsif ($current_function->{abi} eq "svr4") {
my $func = "$current_function->{name} PROC\n".
" mov QWORD PTR 8[rsp],rdi\t;WIN64 prologue\n".
" mov QWORD PTR 16[rsp],rsi\n";
my $narg = $current_function->{narg};
$narg=6 if (!defined($narg));
$func .= " mov rdi,rcx\n" if ($narg>0);
$func .= " mov rsi,rdx\n" if ($narg>1);
$func .= " mov rdx,r8\n" if ($narg>2);
$func .= " mov rcx,r9\n" if ($narg>3);
$func .= " mov r8,QWORD PTR 40[rsp]\n" if ($narg>4);
$func .= " mov r9,QWORD PTR 48[rsp]\n" if ($narg>5);
$func .= "\n";
} else {
"$current_function->{name} PROC";
}
}
}
{ package expr; # pick up expressioins
sub re {
my $self = shift; # single instance is enough...
local *line = shift;
undef $ret;
if ($line =~ /(^[^,]+)/) {
$self->{value} = $1;
$ret = $self;
$line = substr($line,@+[0]); $line =~ s/^\s+//;
$self->{value} =~ s/\.L/\$L/g if ($masm);
}
$ret;
}
sub out {
my $self = shift;
$self->{value};
}
}
{ package directive; # pick up directives, which start with .
sub re {
my $self = shift; # single instance is enough...
local *line = shift;
undef $ret;
my $dir;
my %opcode = # lea 2f-1f(%rip),%dst; 1: nop; 2:
( "%rax"=>0x01058d48, "%rcx"=>0x010d8d48,
"%rdx"=>0x01158d48, "%rbx"=>0x011d8d48,
"%rsp"=>0x01258d48, "%rbp"=>0x012d8d48,
"%rsi"=>0x01358d48, "%rdi"=>0x013d8d48,
"%r8" =>0x01058d4c, "%r9" =>0x010d8d4c,
"%r10"=>0x01158d4c, "%r11"=>0x011d8d4c,
"%r12"=>0x01258d4c, "%r13"=>0x012d8d4c,
"%r14"=>0x01358d4c, "%r15"=>0x013d8d4c );
if ($line =~ /^\s*(\.\w+)/) {
if (!$masm) {
$self->{value} = $1;
$line =~ s/\@abi\-omnipotent/\@function/;
$line =~ s/\@function.*/\@function/;
if ($line =~ /\.picmeup\s+(%r[\w]+)/i) {
$self->{value} = sprintf "\t.long\t0x%x,0x90000000",$opcode{$1};
} else {
$self->{value} = $line;
}
$line = "";
return $self;
}
$dir = $1;
$ret = $self;
undef $self->{value};
$line = substr($line,@+[0]); $line =~ s/^\s+//;
SWITCH: for ($dir) {
/\.(text)/
&& do { my $v=undef;
$v="$current_segment\tENDS\n" if ($current_segment);
$current_segment = "_$1\$";
$current_segment =~ tr/[a-z]/[A-Z]/;
$v.="$current_segment\tSEGMENT ALIGN(64) 'CODE'";
$self->{value} = $v;
last;
};
/\.globl/ && do { $self->{value} = "PUBLIC\t".$line; last; };
/\.type/ && do { ($sym,$type,$narg) = split(',',$line);
if ($type eq "\@function") {
undef $current_function;
$current_function->{name} = $sym;
$current_function->{abi} = "svr4";
$current_function->{narg} = $narg;
} elsif ($type eq "\@abi-omnipotent") {
undef $current_function;
$current_function->{name} = $sym;
}
last;
};
/\.size/ && do { if (defined($current_function)) {
$self->{value}="$current_function->{name}\tENDP";
undef $current_function;
}
last;
};
/\.align/ && do { $self->{value} = "ALIGN\t".$line; last; };
/\.(byte|value|long|quad)/
&& do { my @arr = split(',',$line);
my $sz = substr($1,0,1);
my $last = pop(@arr);
$sz =~ tr/bvlq/BWDQ/;
$self->{value} = "\tD$sz\t";
for (@arr) { $self->{value} .= sprintf"0%Xh,",oct; }
$self->{value} .= sprintf"0%Xh",oct($last);
last;
};
/\.picmeup/ && do { $self->{value} = sprintf"\tDD\t 0%Xh,090000000h",$opcode{$line};
last;
};
}
$line = "";
}
$ret;
}
sub out {
my $self = shift;
$self->{value};
}
}
while($line=<>) {
chomp($line);
$line =~ s|[#!].*$||; # get rid of asm-style comments...
$line =~ s|/\*.*\*/||; # ... and C-style comments...
$line =~ s|^\s+||; # ... and skip white spaces in beginning
undef $label;
undef $opcode;
undef $dst;
undef $src;
undef $sz;
if ($label=label->re(\$line)) { print $label->out(); }
if (directive->re(\$line)) {
printf "%s",directive->out();
} elsif ($opcode=opcode->re(\$line)) { ARGUMENT: {
if ($src=register->re(\$line)) { opcode->size($src->size()); }
elsif ($src=const->re(\$line)) { }
elsif ($src=ea->re(\$line)) { }
elsif ($src=expr->re(\$line)) { }
last ARGUMENT if ($line !~ /^,/);
$line = substr($line,1); $line =~ s/^\s+//;
if ($dst=register->re(\$line)) { opcode->size($dst->size()); }
elsif ($dst=const->re(\$line)) { }
elsif ($dst=ea->re(\$line)) { }
} # ARGUMENT:
$sz=opcode->size();
if (defined($dst)) {
if (!$masm) {
printf "\t%s\t%s,%s", $opcode->out($dst->size()),
$src->out($sz),$dst->out($sz);
} else {
printf "\t%s\t%s,%s", $opcode->out(),
$dst->out($sz),$src->out($sz);
}
} elsif (defined($src)) {
printf "\t%s\t%s",$opcode->out(),$src->out($sz);
} else {
printf "\t%s",$opcode->out();
}
}
print $line,"\n";
}
print "\n$current_segment\tENDS\nEND\n" if ($masm);
close STDOUT;
#################################################
# Cross-reference x86_64 ABI "card"
#
# Unix Win64
# %rax * *
# %rbx - -
# %rcx #4 #1
# %rdx #3 #2
# %rsi #2 -
# %rdi #1 -
# %rbp - -
# %rsp - -
# %r8 #5 #3
# %r9 #6 #4
# %r10 * *
# %r11 * *
# %r12 - -
# %r13 - -
# %r14 - -
# %r15 - -
#
# (*) volatile register
# (-) preserved by callee
# (#) Nth argument, volatile
#
# In Unix terms top of stack is argument transfer area for arguments
# which could not be accomodated in registers. Or in other words 7th
# [integer] argument resides at 8(%rsp) upon function entry point.
# 128 bytes above %rsp constitute a "red zone" which is not touched
# by signal handlers and can be used as temporal storage without
# allocating a frame.
#
# In Win64 terms N*8 bytes on top of stack is argument transfer area,
# which belongs to/can be overwritten by callee. N is the number of
# arguments passed to callee, *but* not less than 4! This means that
# upon function entry point 5th argument resides at 40(%rsp), as well
# as that 32 bytes from 8(%rsp) can always be used as temporal
# storage [without allocating a frame].
#
# All the above means that if assembler programmer adheres to Unix
# register and stack layout, but disregards the "red zone" existense,
# it's possible to use following prologue and epilogue to "gear" from
# Unix to Win64 ABI in leaf functions with not more than 6 arguments.
#
# omnipotent_function:
# ifdef WIN64
# movq %rdi,8(%rsp)
# movq %rsi,16(%rsp)
# movq %rcx,%rdi ; if 1st argument is actually present
# movq %rdx,%rsi ; if 2nd argument is actually ...
# movq %r8,%rdx ; if 3rd argument is ...
# movq %r9,%rcx ; if 4th argument ...
# movq 40(%rsp),%r8 ; if 5th ...
# movq 48(%rsp),%r9 ; if 6th ...
# endif
# ...
# ifdef WIN64
# movq 8(%rsp),%rdi
# movq 16(%rsp),%rsi
# endif
# ret
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