crypto/perlasm/x86_64-xlate.pl

   1 #! /usr/bin/env perl
   2 # Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved.
   3 #
   4 # Licensed under the OpenSSL license (the "License").  You may not use
   5 # this file except in compliance with the License.  You can obtain a copy
   6 # in the file LICENSE in the source distribution or at
   7 # https://www.openssl.org/source/license.html
   8
   9
  10 # Ascetic x86_64 AT&T to MASM/NASM assembler translator by <appro>.
  11 #
  12 # Why AT&T to MASM and not vice versa? Several reasons. Because AT&T
  13 # format is way easier to parse. Because it's simpler to "gear" from
  14 # Unix ABI to Windows one [see cross-reference "card" at the end of
  15 # file]. Because Linux targets were available first...
  16 #
  17 # In addition the script also "distills" code suitable for GNU
  18 # assembler, so that it can be compiled with more rigid assemblers,
  19 # such as Solaris /usr/ccs/bin/as.
  20 #
  21 # This translator is not designed to convert *arbitrary* assembler
  22 # code from AT&T format to MASM one. It's designed to convert just
  23 # enough to provide for dual-ABI OpenSSL modules development...
  24 # There *are* limitations and you might have to modify your assembler
  25 # code or this script to achieve the desired result...
  26 #
  27 # Currently recognized limitations:
  28 #
  29 # - can't use multiple ops per line;
  30 #
  31 # Dual-ABI styling rules.
  32 #
  33 # 1. Adhere to Unix register and stack layout [see cross-reference
  34 #    ABI "card" at the end for explanation].
  35 # 2. Forget about "red zone," stick to more traditional blended
  36 #    stack frame allocation. If volatile storage is actually required
  37 #    that is. If not, just leave the stack as is.
  38 # 3. Functions tagged with ".type name,@function" get crafted with
  39 #    unified Win64 prologue and epilogue automatically. If you want
  40 #    to take care of ABI differences yourself, tag functions as
  41 #    ".type name,@abi-omnipotent" instead.
  42 # 4. To optimize the Win64 prologue you can specify number of input
  43 #    arguments as ".type name,@function,N." Keep in mind that if N is
  44 #    larger than 6, then you *have to* write "abi-omnipotent" code,
  45 #    because >6 cases can't be addressed with unified prologue.
  46 # 5. Name local labels as .L*, do *not* use dynamic labels such as 1:
  47 #    (sorry about latter).
  48 # 6. Don't use [or hand-code with .byte] "rep ret." "ret" mnemonic is
  49 #    required to identify the spots, where to inject Win64 epilogue!
  50 #    But on the pros, it's then prefixed with rep automatically:-)
  51 # 7. Stick to explicit ip-relative addressing. If you have to use
  52 #    GOTPCREL addressing, stick to mov symbol@GOTPCREL(%rip),%r??.
  53 #    Both are recognized and translated to proper Win64 addressing
  54 #    modes. To support legacy code a synthetic directive, .picmeup,
  55 #    is implemented. It puts address of the *next* instruction into
  56 #    target register, e.g.:
  57 #
  58 #               .picmeup        %rax
  59 #               lea             .Label-.(%rax),%rax
  60 #
  61 # 8. In order to provide for structured exception handling unified
  62 #    Win64 prologue copies %rsp value to %rax. For further details
  63 #    see SEH paragraph at the end.
  64 # 9. .init segment is allowed to contain calls to functions only.
  65 # a. If function accepts more than 4 arguments *and* >4th argument
  66 #    is declared as non 64-bit value, do clear its upper part.
  67 \f
  68
  69 use strict;
  70
  71 my $flavour = shift;
  72 my $output  = shift;
  73 if ($flavour =~ /\./) { $output = $flavour; undef $flavour; }
  74
  75 open STDOUT,">$output" || die "can't open $output: $!"
  76         if (defined($output));
  77
  78 my $gas=1;      $gas=0 if ($output =~ /\.asm$/);
  79 my $elf=1;      $elf=0 if (!$gas);
  80 my $win64=0;
  81 my $prefix="";
  82 my $decor=".L";
  83
  84 my $masmref=8 + 50727*2**-32;   # 8.00.50727 shipped with VS2005
  85 my $masm=0;
  86 my $PTR=" PTR";
  87
  88 my $nasmref=2.03;
  89 my $nasm=0;
  90
  91 if    ($flavour eq "mingw64")   { $gas=1; $elf=0; $win64=1;
  92                                   $prefix=`echo __USER_LABEL_PREFIX__ | $ENV{CC} -E -P -`;
  93                                   $prefix =~ s|\R$||; # Better chomp
  94                                 }
  95 elsif ($flavour eq "macosx")    { $gas=1; $elf=0; $prefix="_"; $decor="L\$"; }
  96 elsif ($flavour eq "masm")      { $gas=0; $elf=0; $masm=$masmref; $win64=1; $decor="\$L\$"; }
  97 elsif ($flavour eq "nasm")      { $gas=0; $elf=0; $nasm=$nasmref; $win64=1; $decor="\$L\$"; $PTR=""; }
  98 elsif (!$gas)
  99 {   if ($ENV{ASM} =~ m/nasm/ && `nasm -v` =~ m/version ([0-9]+)\.([0-9]+)/i)
 100     {   $nasm = $1 + $2*0.01; $PTR="";  }
 101     elsif (`ml64 2>&1` =~ m/Version ([0-9]+)\.([0-9]+)(\.([0-9]+))?/)
 102     {   $masm = $1 + $2*2**-16 + $4*2**-32;   }
 103     die "no assembler found on %PATH" if (!($nasm || $masm));
 104     $win64=1;
 105     $elf=0;
 106     $decor="\$L\$";
 107 }
 108
 109 my $current_segment;
 110 my $current_function;
 111 my %globals;
 112
 113 { package opcode;       # pick up opcodes
 114     sub re {
 115         my      ($class, $line) = @_;
 116         my      $self = {};
 117         my      $ret;
 118
 119         if ($$line =~ /^([a-z][a-z0-9]*)/i) {
 120             bless $self,$class;
 121             $self->{op} = $1;
 122             $ret = $self;
 123             $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
 124
 125             undef $self->{sz};
 126             if ($self->{op} =~ /^(movz)x?([bw]).*/) {   # movz is pain...
 127                 $self->{op} = $1;
 128                 $self->{sz} = $2;
 129             } elsif ($self->{op} =~ /call|jmp/) {
 130                 $self->{sz} = "";
 131             } elsif ($self->{op} =~ /^p/ && $' !~ /^(ush|op|insrw)/) { # SSEn
 132                 $self->{sz} = "";
 133             } elsif ($self->{op} =~ /^v/) { # VEX
 134                 $self->{sz} = "";
 135             } elsif ($self->{op} =~ /mov[dq]/ && $$line =~ /%xmm/) {
 136                 $self->{sz} = "";
 137             } elsif ($self->{op} =~ /([a-z]{3,})([qlwb])$/) {
 138                 $self->{op} = $1;
 139                 $self->{sz} = $2;
 140             }
 141         }
 142         $ret;
 143     }
 144     sub size {
 145         my ($self, $sz) = @_;
 146         $self->{sz} = $sz if (defined($sz) && !defined($self->{sz}));
 147         $self->{sz};
 148     }
 149     sub out {
 150         my $self = shift;
 151         if ($gas) {
 152             if ($self->{op} eq "movz") {        # movz is pain...
 153                 sprintf "%s%s%s",$self->{op},$self->{sz},shift;
 154             } elsif ($self->{op} =~ /^set/) {
 155                 "$self->{op}";
 156             } elsif ($self->{op} eq "ret") {
 157                 my $epilogue = "";
 158                 if ($win64 && $current_function->{abi} eq "svr4") {
 159                     $epilogue = "movq   8(%rsp),%rdi\n\t" .
 160                                 "movq   16(%rsp),%rsi\n\t";
 161                 }
 162                 $epilogue . ".byte      0xf3,0xc3";
 163             } elsif ($self->{op} eq "call" && !$elf && $current_segment eq ".init") {
 164                 ".p2align\t3\n\t.quad";
 165             } else {
 166                 "$self->{op}$self->{sz}";
 167             }
 168         } else {
 169             $self->{op} =~ s/^movz/movzx/;
 170             if ($self->{op} eq "ret") {
 171                 $self->{op} = "";
 172                 if ($win64 && $current_function->{abi} eq "svr4") {
 173                     $self->{op} = "mov  rdi,QWORD$PTR\[8+rsp\]\t;WIN64 epilogue\n\t".
 174                                   "mov  rsi,QWORD$PTR\[16+rsp\]\n\t";
 175                 }
 176                 $self->{op} .= "DB\t0F3h,0C3h\t\t;repret";
 177             } elsif ($self->{op} =~ /^(pop|push)f/) {
 178                 $self->{op} .= $self->{sz};
 179             } elsif ($self->{op} eq "call" && $current_segment eq ".CRT\$XCU") {
 180                 $self->{op} = "\tDQ";
 181             }
 182             $self->{op};
 183         }
 184     }
 185     sub mnemonic {
 186         my ($self, $op) = @_;
 187         $self->{op}=$op if (defined($op));
 188         $self->{op};
 189     }
 190 }
 191 { package const;        # pick up constants, which start with $
 192     sub re {
 193         my      ($class, $line) = @_;
 194         my      $self = {};
 195         my      $ret;
 196
 197         if ($$line =~ /^\$([^,]+)/) {
 198             bless $self, $class;
 199             $self->{value} = $1;
 200             $ret = $self;
 201             $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
 202         }
 203         $ret;
 204     }
 205     sub out {
 206         my $self = shift;
 207
 208         $self->{value} =~ s/\b(0b[0-1]+)/oct($1)/eig;
 209         if ($gas) {
 210             # Solaris /usr/ccs/bin/as can't handle multiplications
 211             # in $self->{value}
 212             my $value = $self->{value};
 213             no warnings;    # oct might complain about overflow, ignore here...
 214             $value =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi;
 215             if ($value =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg) {
 216                 $self->{value} = $value;
 217             }
 218             sprintf "\$%s",$self->{value};
 219         } else {
 220             $self->{value} =~ s/0x([0-9a-f]+)/0$1h/ig if ($masm);
 221             sprintf "%s",$self->{value};
 222         }
 223     }
 224 }
 225 { package ea;           # pick up effective addresses: expr(%reg,%reg,scale)
 226     sub re {
 227         my      ($class, $line, $opcode) = @_;
 228         my      $self = {};
 229         my      $ret;
 230
 231         # optional * ----vvv--- appears in indirect jmp/call
 232         if ($$line =~ /^(\*?)([^\(,]*)\(([%\w,]+)\)/) {
 233             bless $self, $class;
 234             $self->{asterisk} = $1;
 235             $self->{label} = $2;
 236             ($self->{base},$self->{index},$self->{scale})=split(/,/,$3);
 237             $self->{scale} = 1 if (!defined($self->{scale}));
 238             $ret = $self;
 239             $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
 240
 241             if ($win64 && $self->{label} =~ s/\@GOTPCREL//) {
 242                 die if ($opcode->mnemonic() ne "mov");
 243                 $opcode->mnemonic("lea");
 244             }
 245             $self->{base}  =~ s/^%//;
 246             $self->{index} =~ s/^%// if (defined($self->{index}));
 247             $self->{opcode} = $opcode;
 248         }
 249         $ret;
 250     }
 251     sub size {}
 252     sub out {
 253         my ($self, $sz) = @_;
 254
 255         $self->{label} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
 256         $self->{label} =~ s/\.L/$decor/g;
 257
 258         # Silently convert all EAs to 64-bit. This is required for
 259         # elder GNU assembler and results in more compact code,
 260         # *but* most importantly AES module depends on this feature!
 261         $self->{index} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/;
 262         $self->{base}  =~ s/^[er](.?[0-9xpi])[d]?$/r\1/;
 263
 264         # Solaris /usr/ccs/bin/as can't handle multiplications
 265         # in $self->{label}, new gas requires sign extension...
 266         use integer;
 267         $self->{label} =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi;
 268         $self->{label} =~ s/\b([0-9]+\s*[\*\/\%]\s*[0-9]+)\b/eval($1)/eg;
 269         $self->{label} =~ s/\b([0-9]+)\b/$1<<32>>32/eg;
 270
 271         if (!$self->{label} && $self->{index} && $self->{scale}==1 &&
 272             $self->{base} =~ /(rbp|r13)/) {
 273                 $self->{base} = $self->{index}; $self->{index} = $1;
 274         }
 275
 276         if ($gas) {
 277             $self->{label} =~ s/^___imp_/__imp__/   if ($flavour eq "mingw64");
 278
 279             if (defined($self->{index})) {
 280                 sprintf "%s%s(%s,%%%s,%d)",$self->{asterisk},
 281                                         $self->{label},
 282                                         $self->{base}?"%$self->{base}":"",
 283                                         $self->{index},$self->{scale};
 284             } else {
 285                 sprintf "%s%s(%%%s)",   $self->{asterisk},$self->{label},$self->{base};
 286             }
 287         } else {
 288             my %szmap = (       b=>"BYTE$PTR",  w=>"WORD$PTR",
 289                         l=>"DWORD$PTR", d=>"DWORD$PTR",
 290                         q=>"QWORD$PTR", o=>"OWORD$PTR",
 291                         x=>"XMMWORD$PTR", y=>"YMMWORD$PTR", z=>"ZMMWORD$PTR" );
 292
 293             $self->{label} =~ s/\./\$/g;
 294             $self->{label} =~ s/(?<![\w\$\.])0x([0-9a-f]+)/0$1h/ig;
 295             $self->{label} = "($self->{label})" if ($self->{label} =~ /[\*\+\-\/]/);
 296
 297             my $mnemonic = $self->{opcode}->mnemonic();
 298             ($self->{asterisk})                         && ($sz="q") ||
 299             ($mnemonic =~ /^v?mov([qd])$/)              && ($sz=$1)  ||
 300             ($mnemonic =~ /^v?pinsr([qdwb])$/)          && ($sz=$1)  ||
 301             ($mnemonic =~ /^vpbroadcast([qdwb])$/)      && ($sz=$1)  ||
 302             ($mnemonic =~ /^v(?!perm)[a-z]+[fi]128$/)   && ($sz="x");
 303
 304             if (defined($self->{index})) {
 305                 sprintf "%s[%s%s*%d%s]",$szmap{$sz},
 306                                         $self->{label}?"$self->{label}+":"",
 307                                         $self->{index},$self->{scale},
 308                                         $self->{base}?"+$self->{base}":"";
 309             } elsif ($self->{base} eq "rip") {
 310                 sprintf "%s[%s]",$szmap{$sz},$self->{label};
 311             } else {
 312                 sprintf "%s[%s%s]",$szmap{$sz},
 313                                         $self->{label}?"$self->{label}+":"",
 314                                         $self->{base};
 315             }
 316         }
 317     }
 318 }
 319 { package register;     # pick up registers, which start with %.
 320     sub re {
 321         my      ($class, $line, $opcode) = @_;
 322         my      $self = {};
 323         my      $ret;
 324
 325         # optional * ----vvv--- appears in indirect jmp/call
 326         if ($$line =~ /^(\*?)%(\w+)/) {
 327             bless $self,$class;
 328             $self->{asterisk} = $1;
 329             $self->{value} = $2;
 330             $opcode->size($self->size());
 331             $ret = $self;
 332             $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
 333         }
 334         $ret;
 335     }
 336     sub size {
 337         my      $self = shift;
 338         my      $ret;
 339
 340         if    ($self->{value} =~ /^r[\d]+b$/i)  { $ret="b"; }
 341         elsif ($self->{value} =~ /^r[\d]+w$/i)  { $ret="w"; }
 342         elsif ($self->{value} =~ /^r[\d]+d$/i)  { $ret="l"; }
 343         elsif ($self->{value} =~ /^r[\w]+$/i)   { $ret="q"; }
 344         elsif ($self->{value} =~ /^[a-d][hl]$/i){ $ret="b"; }
 345         elsif ($self->{value} =~ /^[\w]{2}l$/i) { $ret="b"; }
 346         elsif ($self->{value} =~ /^[\w]{2}$/i)  { $ret="w"; }
 347         elsif ($self->{value} =~ /^e[a-z]{2}$/i){ $ret="l"; }
 348
 349         $ret;
 350     }
 351     sub out {
 352         my $self = shift;
 353         if ($gas)       { sprintf "%s%%%s",$self->{asterisk},$self->{value}; }
 354         else            { $self->{value}; }
 355     }
 356 }
 357 { package label;        # pick up labels, which end with :
 358     sub re {
 359         my      ($class, $line) = @_;
 360         my      $self = {};
 361         my      $ret;
 362
 363         if ($$line =~ /(^[\.\w]+)\:/) {
 364             bless $self,$class;
 365             $self->{value} = $1;
 366             $ret = $self;
 367             $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
 368
 369             $self->{value} =~ s/^\.L/$decor/;
 370         }
 371         $ret;
 372     }
 373     sub out {
 374         my $self = shift;
 375
 376         if ($gas) {
 377             my $func = ($globals{$self->{value}} or $self->{value}) . ":";
 378             if ($win64  &&
 379                         $current_function->{name} eq $self->{value} &&
 380                         $current_function->{abi} eq "svr4") {
 381                 $func .= "\n";
 382                 $func .= "      movq    %rdi,8(%rsp)\n";
 383                 $func .= "      movq    %rsi,16(%rsp)\n";
 384                 $func .= "      movq    %rsp,%rax\n";
 385                 $func .= "${decor}SEH_begin_$current_function->{name}:\n";
 386                 my $narg = $current_function->{narg};
 387                 $narg=6 if (!defined($narg));
 388                 $func .= "      movq    %rcx,%rdi\n" if ($narg>0);
 389                 $func .= "      movq    %rdx,%rsi\n" if ($narg>1);
 390                 $func .= "      movq    %r8,%rdx\n"  if ($narg>2);
 391                 $func .= "      movq    %r9,%rcx\n"  if ($narg>3);
 392                 $func .= "      movq    40(%rsp),%r8\n" if ($narg>4);
 393                 $func .= "      movq    48(%rsp),%r9\n" if ($narg>5);
 394             }
 395             $func;
 396         } elsif ($self->{value} ne "$current_function->{name}") {
 397             # Make all labels in masm global.
 398             $self->{value} .= ":" if ($masm);
 399             $self->{value} . ":";
 400         } elsif ($win64 && $current_function->{abi} eq "svr4") {
 401             my $func =  "$current_function->{name}" .
 402                         ($nasm ? ":" : "\tPROC $current_function->{scope}") .
 403                         "\n";
 404             $func .= "  mov     QWORD$PTR\[8+rsp\],rdi\t;WIN64 prologue\n";
 405             $func .= "  mov     QWORD$PTR\[16+rsp\],rsi\n";
 406             $func .= "  mov     rax,rsp\n";
 407             $func .= "${decor}SEH_begin_$current_function->{name}:";
 408             $func .= ":" if ($masm);
 409             $func .= "\n";
 410             my $narg = $current_function->{narg};
 411             $narg=6 if (!defined($narg));
 412             $func .= "  mov     rdi,rcx\n" if ($narg>0);
 413             $func .= "  mov     rsi,rdx\n" if ($narg>1);
 414             $func .= "  mov     rdx,r8\n"  if ($narg>2);
 415             $func .= "  mov     rcx,r9\n"  if ($narg>3);
 416             $func .= "  mov     r8,QWORD$PTR\[40+rsp\]\n" if ($narg>4);
 417             $func .= "  mov     r9,QWORD$PTR\[48+rsp\]\n" if ($narg>5);
 418             $func .= "\n";
 419         } else {
 420            "$current_function->{name}".
 421                         ($nasm ? ":" : "\tPROC $current_function->{scope}");
 422         }
 423     }
 424 }
 425 { package expr;         # pick up expressioins
 426     sub re {
 427         my      ($class, $line, $opcode) = @_;
 428         my      $self = {};
 429         my      $ret;
 430
 431         if ($$line =~ /(^[^,]+)/) {
 432             bless $self,$class;
 433             $self->{value} = $1;
 434             $ret = $self;
 435             $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
 436
 437             $self->{value} =~ s/\@PLT// if (!$elf);
 438             $self->{value} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
 439             $self->{value} =~ s/\.L/$decor/g;
 440             $self->{opcode} = $opcode;
 441         }
 442         $ret;
 443     }
 444     sub out {
 445         my $self = shift;
 446         if ($nasm && $self->{opcode}->mnemonic()=~m/^j(?![re]cxz)/) {
 447             "NEAR ".$self->{value};
 448         } else {
 449             $self->{value};
 450         }
 451     }
 452 }
 453 { package directive;    # pick up directives, which start with .
 454     sub re {
 455         my      ($class, $line) = @_;
 456         my      $self = {};
 457         my      $ret;
 458         my      $dir;
 459         my      %opcode =       # lea 2f-1f(%rip),%dst; 1: nop; 2:
 460                 (       "%rax"=>0x01058d48,     "%rcx"=>0x010d8d48,
 461                         "%rdx"=>0x01158d48,     "%rbx"=>0x011d8d48,
 462                         "%rsp"=>0x01258d48,     "%rbp"=>0x012d8d48,
 463                         "%rsi"=>0x01358d48,     "%rdi"=>0x013d8d48,
 464                         "%r8" =>0x01058d4c,     "%r9" =>0x010d8d4c,
 465                         "%r10"=>0x01158d4c,     "%r11"=>0x011d8d4c,
 466                         "%r12"=>0x01258d4c,     "%r13"=>0x012d8d4c,
 467                         "%r14"=>0x01358d4c,     "%r15"=>0x013d8d4c      );
 468
 469         if ($$line =~ /^\s*(\.\w+)/) {
 470             bless $self,$class;
 471             $dir = $1;
 472             $ret = $self;
 473             undef $self->{value};
 474             $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
 475
 476             SWITCH: for ($dir) {
 477                 /\.picmeup/ && do { if ($$line =~ /(%r[\w]+)/i) {
 478                                         $dir="\t.long";
 479                                         $$line=sprintf "0x%x,0x90000000",$opcode{$1};
 480                                     }
 481                                     last;
 482                                   };
 483                 /\.global|\.globl|\.extern/
 484                             && do { $globals{$$line} = $prefix . $$line;
 485                                     $$line = $globals{$$line} if ($prefix);
 486                                     last;
 487                                   };
 488                 /\.type/    && do { my ($sym,$type,$narg) = split(',',$$line);
 489                                     if ($type eq "\@function") {
 490                                         undef $current_function;
 491                                         $current_function->{name} = $sym;
 492                                         $current_function->{abi}  = "svr4";
 493                                         $current_function->{narg} = $narg;
 494                                         $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE";
 495                                     } elsif ($type eq "\@abi-omnipotent") {
 496                                         undef $current_function;
 497                                         $current_function->{name} = $sym;
 498                                         $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE";
 499                                     }
 500                                     $$line =~ s/\@abi\-omnipotent/\@function/;
 501                                     $$line =~ s/\@function.*/\@function/;
 502                                     last;
 503                                   };
 504                 /\.asciz/   && do { if ($$line =~ /^"(.*)"$/) {
 505                                         $dir  = ".byte";
 506                                         $$line = join(",",unpack("C*",$1),0);
 507                                     }
 508                                     last;
 509                                   };
 510                 /\.rva|\.long|\.quad/
 511                             && do { $$line =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
 512                                     $$line =~ s/\.L/$decor/g;
 513                                     last;
 514                                   };
 515             }
 516
 517             if ($gas) {
 518                 $self->{value} = $dir . "\t" . $$line;
 519
 520                 if ($dir =~ /\.extern/) {
 521                     $self->{value} = ""; # swallow extern
 522                 } elsif (!$elf && $dir =~ /\.type/) {
 523                     $self->{value} = "";
 524                     $self->{value} = ".def\t" . ($globals{$1} or $1) . ";\t" .
 525                                 (defined($globals{$1})?".scl 2;":".scl 3;") .
 526                                 "\t.type 32;\t.endef"
 527                                 if ($win64 && $$line =~ /([^,]+),\@function/);
 528                 } elsif (!$elf && $dir =~ /\.size/) {
 529                     $self->{value} = "";
 530                     if (defined($current_function)) {
 531                         $self->{value} .= "${decor}SEH_end_$current_function->{name}:"
 532                                 if ($win64 && $current_function->{abi} eq "svr4");
 533                         undef $current_function;
 534                     }
 535                 } elsif (!$elf && $dir =~ /\.align/) {
 536                     $self->{value} = ".p2align\t" . (log($$line)/log(2));
 537                 } elsif ($dir eq ".section") {
 538                     $current_segment=$$line;
 539                     if (!$elf && $current_segment eq ".init") {
 540                         if      ($flavour eq "macosx")  { $self->{value} = ".mod_init_func"; }
 541                         elsif   ($flavour eq "mingw64") { $self->{value} = ".section\t.ctors"; }
 542                     }
 543                 } elsif ($dir =~ /\.(text|data)/) {
 544                     $current_segment=".$1";
 545                 } elsif ($dir =~ /\.hidden/) {
 546                     if    ($flavour eq "macosx")  { $self->{value} = ".private_extern\t$prefix$$line"; }
 547                     elsif ($flavour eq "mingw64") { $self->{value} = ""; }
 548                 } elsif ($dir =~ /\.comm/) {
 549                     $self->{value} = "$dir\t$prefix$$line";
 550                     $self->{value} =~ s|,([0-9]+),([0-9]+)$|",$1,".log($2)/log(2)|e if ($flavour eq "macosx");
 551                 }
 552                 $$line = "";
 553                 return $self;
 554             }
 555
 556             # non-gas case or nasm/masm
 557             SWITCH: for ($dir) {
 558                 /\.text/    && do { my $v=undef;
 559                                     if ($nasm) {
 560                                         $v="section     .text code align=64\n";
 561                                     } else {
 562                                         $v="$current_segment\tENDS\n" if ($current_segment);
 563                                         $current_segment = ".text\$";
 564                                         $v.="$current_segment\tSEGMENT ";
 565                                         $v.=$masm>=$masmref ? "ALIGN(256)" : "PAGE";
 566                                         $v.=" 'CODE'";
 567                                     }
 568                                     $self->{value} = $v;
 569                                     last;
 570                                   };
 571                 /\.data/    && do { my $v=undef;
 572                                     if ($nasm) {
 573                                         $v="section     .data data align=8\n";
 574                                     } else {
 575                                         $v="$current_segment\tENDS\n" if ($current_segment);
 576                                         $current_segment = "_DATA";
 577                                         $v.="$current_segment\tSEGMENT";
 578                                     }
 579                                     $self->{value} = $v;
 580                                     last;
 581                                   };
 582                 /\.section/ && do { my $v=undef;
 583                                     $$line =~ s/([^,]*).*/$1/;
 584                                     $$line = ".CRT\$XCU" if ($$line eq ".init");
 585                                     if ($nasm) {
 586                                         $v="section     $$line";
 587                                         if ($$line=~/\.([px])data/) {
 588                                             $v.=" rdata align=";
 589                                             $v.=$1 eq "p"? 4 : 8;
 590                                         } elsif ($$line=~/\.CRT\$/i) {
 591                                             $v.=" rdata align=8";
 592                                         }
 593                                     } else {
 594                                         $v="$current_segment\tENDS\n" if ($current_segment);
 595                                         $v.="$$line\tSEGMENT";
 596                                         if ($$line=~/\.([px])data/) {
 597                                             $v.=" READONLY";
 598                                             $v.=" ALIGN(".($1 eq "p" ? 4 : 8).")" if ($masm>=$masmref);
 599                                         } elsif ($$line=~/\.CRT\$/i) {
 600                                             $v.=" READONLY ";
 601                                             $v.=$masm>=$masmref ? "ALIGN(8)" : "DWORD";
 602                                         }
 603                                     }
 604                                     $current_segment = $$line;
 605                                     $self->{value} = $v;
 606                                     last;
 607                                   };
 608                 /\.extern/  && do { $self->{value}  = "EXTERN\t".$$line;
 609                                     $self->{value} .= ":NEAR" if ($masm);
 610                                     last;
 611                                   };
 612                 /\.globl|.global/
 613                             && do { $self->{value}  = $masm?"PUBLIC":"global";
 614                                     $self->{value} .= "\t".$$line;
 615                                     last;
 616                                   };
 617                 /\.size/    && do { if (defined($current_function)) {
 618                                         undef $self->{value};
 619                                         if ($current_function->{abi} eq "svr4") {
 620                                             $self->{value}="${decor}SEH_end_$current_function->{name}:";
 621                                             $self->{value}.=":\n" if($masm);
 622                                         }
 623                                         $self->{value}.="$current_function->{name}\tENDP" if($masm && $current_function->{name});
 624                                         undef $current_function;
 625                                     }
 626                                     last;
 627                                   };
 628                 /\.align/   && do { my $max = ($masm && $masm>=$masmref) ? 256 : 4096;
 629                                     $self->{value} = "ALIGN\t".($$line>$max?$max:$$line);
 630                                     last;
 631                                   };
 632                 /\.(value|long|rva|quad)/
 633                             && do { my $sz  = substr($1,0,1);
 634                                     my @arr = split(/,\s*/,$$line);
 635                                     my $last = pop(@arr);
 636                                     my $conv = sub  {   my $var=shift;
 637                                                         $var=~s/^(0b[0-1]+)/oct($1)/eig;
 638                                                         $var=~s/^0x([0-9a-f]+)/0$1h/ig if ($masm);
 639                                                         if ($sz eq "D" && ($current_segment=~/.[px]data/ || $dir eq ".rva"))
 640                                                         { $var=~s/([_a-z\$\@][_a-z0-9\$\@]*)/$nasm?"$1 wrt ..imagebase":"imagerel $1"/egi; }
 641                                                         $var;
 642                                                     };
 643
 644                                     $sz =~ tr/bvlrq/BWDDQ/;
 645                                     $self->{value} = "\tD$sz\t";
 646                                     for (@arr) { $self->{value} .= &$conv($_).","; }
 647                                     $self->{value} .= &$conv($last);
 648                                     last;
 649                                   };
 650                 /\.byte/    && do { my @str=split(/,\s*/,$$line);
 651                                     map(s/(0b[0-1]+)/oct($1)/eig,@str);
 652                                     map(s/0x([0-9a-f]+)/0$1h/ig,@str) if ($masm);
 653                                     while ($#str>15) {
 654                                         $self->{value}.="DB\t"
 655                                                 .join(",",@str[0..15])."\n";
 656                                         foreach (0..15) { shift @str; }
 657                                     }
 658                                     $self->{value}.="DB\t"
 659                                                 .join(",",@str) if (@str);
 660                                     last;
 661                                   };
 662                 /\.comm/    && do { my @str=split(/,\s*/,$$line);
 663                                     my $v=undef;
 664                                     if ($nasm) {
 665                                         $v.="common     $prefix@str[0] @str[1]";
 666                                     } else {
 667                                         $v="$current_segment\tENDS\n" if ($current_segment);
 668                                         $current_segment = "_DATA";
 669                                         $v.="$current_segment\tSEGMENT\n";
 670                                         $v.="COMM       @str[0]:DWORD:".@str[1]/4;
 671                                     }
 672                                     $self->{value} = $v;
 673                                     last;
 674                                   };
 675             }
 676             $$line = "";
 677         }
 678
 679         $ret;
 680     }
 681     sub out {
 682         my $self = shift;
 683         $self->{value};
 684     }
 685 }
 686
 687 sub rex {
 688  my $opcode=shift;
 689  my ($dst,$src,$rex)=@_;
 690
 691    $rex|=0x04 if($dst>=8);
 692    $rex|=0x01 if($src>=8);
 693    push @$opcode,($rex|0x40) if ($rex);
 694 }
 695
 696 # Upon initial x86_64 introduction SSE>2 extensions were not introduced
 697 # yet. In order not to be bothered by tracing exact assembler versions,
 698 # but at the same time to provide a bare security minimum of AES-NI, we
 699 # hard-code some instructions. Extensions past AES-NI on the other hand
 700 # are traced by examining assembler version in individual perlasm
 701 # modules...
 702
 703 my %regrm = (   "%eax"=>0, "%ecx"=>1, "%edx"=>2, "%ebx"=>3,
 704                 "%esp"=>4, "%ebp"=>5, "%esi"=>6, "%edi"=>7      );
 705
 706 my $movq = sub {        # elderly gas can't handle inter-register movq
 707   my $arg = shift;
 708   my @opcode=(0x66);
 709     if ($arg =~ /%xmm([0-9]+),\s*%r(\w+)/) {
 710         my ($src,$dst)=($1,$2);
 711         if ($dst !~ /[0-9]+/)   { $dst = $regrm{"%e$dst"}; }
 712         rex(\@opcode,$src,$dst,0x8);
 713         push @opcode,0x0f,0x7e;
 714         push @opcode,0xc0|(($src&7)<<3)|($dst&7);       # ModR/M
 715         @opcode;
 716     } elsif ($arg =~ /%r(\w+),\s*%xmm([0-9]+)/) {
 717         my ($src,$dst)=($2,$1);
 718         if ($dst !~ /[0-9]+/)   { $dst = $regrm{"%e$dst"}; }
 719         rex(\@opcode,$src,$dst,0x8);
 720         push @opcode,0x0f,0x6e;
 721         push @opcode,0xc0|(($src&7)<<3)|($dst&7);       # ModR/M
 722         @opcode;
 723     } else {
 724         ();
 725     }
 726 };
 727
 728 my $pextrd = sub {
 729     if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*(%\w+)/) {
 730       my @opcode=(0x66);
 731         my $imm=$1;
 732         my $src=$2;
 733         my $dst=$3;
 734         if ($dst =~ /%r([0-9]+)d/)      { $dst = $1; }
 735         elsif ($dst =~ /%e/)            { $dst = $regrm{$dst}; }
 736         rex(\@opcode,$src,$dst);
 737         push @opcode,0x0f,0x3a,0x16;
 738         push @opcode,0xc0|(($src&7)<<3)|($dst&7);       # ModR/M
 739         push @opcode,$imm;
 740         @opcode;
 741     } else {
 742         ();
 743     }
 744 };
 745
 746 my $pinsrd = sub {
 747     if (shift =~ /\$([0-9]+),\s*(%\w+),\s*%xmm([0-9]+)/) {
 748       my @opcode=(0x66);
 749         my $imm=$1;
 750         my $src=$2;
 751         my $dst=$3;
 752         if ($src =~ /%r([0-9]+)/)       { $src = $1; }
 753         elsif ($src =~ /%e/)            { $src = $regrm{$src}; }
 754         rex(\@opcode,$dst,$src);
 755         push @opcode,0x0f,0x3a,0x22;
 756         push @opcode,0xc0|(($dst&7)<<3)|($src&7);       # ModR/M
 757         push @opcode,$imm;
 758         @opcode;
 759     } else {
 760         ();
 761     }
 762 };
 763
 764 my $pshufb = sub {
 765     if (shift =~ /%xmm([0-9]+),\s*%xmm([0-9]+)/) {
 766       my @opcode=(0x66);
 767         rex(\@opcode,$2,$1);
 768         push @opcode,0x0f,0x38,0x00;
 769         push @opcode,0xc0|($1&7)|(($2&7)<<3);           # ModR/M
 770         @opcode;
 771     } else {
 772         ();
 773     }
 774 };
 775
 776 my $palignr = sub {
 777     if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
 778       my @opcode=(0x66);
 779         rex(\@opcode,$3,$2);
 780         push @opcode,0x0f,0x3a,0x0f;
 781         push @opcode,0xc0|($2&7)|(($3&7)<<3);           # ModR/M
 782         push @opcode,$1;
 783         @opcode;
 784     } else {
 785         ();
 786     }
 787 };
 788
 789 my $pclmulqdq = sub {
 790     if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
 791       my @opcode=(0x66);
 792         rex(\@opcode,$3,$2);
 793         push @opcode,0x0f,0x3a,0x44;
 794         push @opcode,0xc0|($2&7)|(($3&7)<<3);           # ModR/M
 795         my $c=$1;
 796         push @opcode,$c=~/^0/?oct($c):$c;
 797         @opcode;
 798     } else {
 799         ();
 800     }
 801 };
 802
 803 my $rdrand = sub {
 804     if (shift =~ /%[er](\w+)/) {
 805       my @opcode=();
 806       my $dst=$1;
 807         if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; }
 808         rex(\@opcode,0,$dst,8);
 809         push @opcode,0x0f,0xc7,0xf0|($dst&7);
 810         @opcode;
 811     } else {
 812         ();
 813     }
 814 };
 815
 816 my $rdseed = sub {
 817     if (shift =~ /%[er](\w+)/) {
 818       my @opcode=();
 819       my $dst=$1;
 820         if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; }
 821         rex(\@opcode,0,$dst,8);
 822         push @opcode,0x0f,0xc7,0xf8|($dst&7);
 823         @opcode;
 824     } else {
 825         ();
 826     }
 827 };
 828
 829 sub rxb {
 830  my $opcode=shift;
 831  my ($dst,$src1,$src2,$rxb)=@_;
 832
 833    $rxb|=0x7<<5;
 834    $rxb&=~(0x04<<5) if($dst>=8);
 835    $rxb&=~(0x01<<5) if($src1>=8);
 836    $rxb&=~(0x02<<5) if($src2>=8);
 837    push @$opcode,$rxb;
 838 }
 839
 840 my $vprotd = sub {
 841     if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
 842       my @opcode=(0x8f);
 843         rxb(\@opcode,$3,$2,-1,0x08);
 844         push @opcode,0x78,0xc2;
 845         push @opcode,0xc0|($2&7)|(($3&7)<<3);           # ModR/M
 846         my $c=$1;
 847         push @opcode,$c=~/^0/?oct($c):$c;
 848         @opcode;
 849     } else {
 850         ();
 851     }
 852 };
 853
 854 my $vprotq = sub {
 855     if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
 856       my @opcode=(0x8f);
 857         rxb(\@opcode,$3,$2,-1,0x08);
 858         push @opcode,0x78,0xc3;
 859         push @opcode,0xc0|($2&7)|(($3&7)<<3);           # ModR/M
 860         my $c=$1;
 861         push @opcode,$c=~/^0/?oct($c):$c;
 862         @opcode;
 863     } else {
 864         ();
 865     }
 866 };
 867
 868 my $endbranch = sub {
 869     (0xf3,0x0f,0x1e,0xfa);
 870 };
 871
 872 if ($nasm) {
 873     print <<___;
 874 default rel
 875 %define XMMWORD
 876 %define YMMWORD
 877 %define ZMMWORD
 878 ___
 879 } elsif ($masm) {
 880     print <<___;
 881 OPTION  DOTNAME
 882 ___
 883 }
 884 while(defined(my $line=<>)) {
 885
 886     $line =~ s|\R$||;           # Better chomp
 887
 888     $line =~ s|[#!].*$||;       # get rid of asm-style comments...
 889     $line =~ s|/\*.*\*/||;      # ... and C-style comments...
 890     $line =~ s|^\s+||;          # ... and skip white spaces in beginning
 891     $line =~ s|\s+$||;          # ... and at the end
 892
 893     if (my $label=label->re(\$line))    { print $label->out(); }
 894
 895     if (my $directive=directive->re(\$line)) {
 896         printf "%s",$directive->out();
 897     } elsif (my $opcode=opcode->re(\$line)) {
 898         my $asm = eval("\$".$opcode->mnemonic());
 899
 900         if ((ref($asm) eq 'CODE') && scalar(my @bytes=&$asm($line))) {
 901             print $gas?".byte\t":"DB\t",join(',',@bytes),"\n";
 902             next;
 903         }
 904
 905         my @args;
 906         ARGUMENT: while (1) {
 907             my $arg;
 908
 909             ($arg=register->re(\$line, $opcode))||
 910             ($arg=const->re(\$line))            ||
 911             ($arg=ea->re(\$line, $opcode))      ||
 912             ($arg=expr->re(\$line, $opcode))    ||
 913             last ARGUMENT;
 914
 915             push @args,$arg;
 916
 917             last ARGUMENT if ($line !~ /^,/);
 918
 919             $line =~ s/^,\s*//;
 920         } # ARGUMENT:
 921
 922         if ($#args>=0) {
 923             my $insn;
 924             my $sz=$opcode->size();
 925
 926             if ($gas) {
 927                 $insn = $opcode->out($#args>=1?$args[$#args]->size():$sz);
 928                 @args = map($_->out($sz),@args);
 929                 printf "\t%s\t%s",$insn,join(",",@args);
 930             } else {
 931                 $insn = $opcode->out();
 932                 foreach (@args) {
 933                     my $arg = $_->out();
 934                     # $insn.=$sz compensates for movq, pinsrw, ...
 935                     if ($arg =~ /^xmm[0-9]+$/) { $insn.=$sz; $sz="x" if(!$sz); last; }
 936                     if ($arg =~ /^ymm[0-9]+$/) { $insn.=$sz; $sz="y" if(!$sz); last; }
 937                     if ($arg =~ /^zmm[0-9]+$/) { $insn.=$sz; $sz="z" if(!$sz); last; }
 938                     if ($arg =~ /^mm[0-9]+$/)  { $insn.=$sz; $sz="q" if(!$sz); last; }
 939                 }
 940                 @args = reverse(@args);
 941                 undef $sz if ($nasm && $opcode->mnemonic() eq "lea");
 942                 printf "\t%s\t%s",$insn,join(",",map($_->out($sz),@args));
 943             }
 944         } else {
 945             printf "\t%s",$opcode->out();
 946         }
 947     }
 948
 949     print $line,"\n";
 950 }
 951
 952 print "\n$current_segment\tENDS\n"      if ($current_segment && $masm);
 953 print "END\n"                           if ($masm);
 954
 955 close STDOUT;
 956
 957 \f#################################################
 958 # Cross-reference x86_64 ABI "card"
 959 #
 960 #               Unix            Win64
 961 # %rax          *               *
 962 # %rbx          -               -
 963 # %rcx          #4              #1
 964 # %rdx          #3              #2
 965 # %rsi          #2              -
 966 # %rdi          #1              -
 967 # %rbp          -               -
 968 # %rsp          -               -
 969 # %r8           #5              #3
 970 # %r9           #6              #4
 971 # %r10          *               *
 972 # %r11          *               *
 973 # %r12          -               -
 974 # %r13          -               -
 975 # %r14          -               -
 976 # %r15          -               -
 977 #
 978 # (*)   volatile register
 979 # (-)   preserved by callee
 980 # (#)   Nth argument, volatile
 981 #
 982 # In Unix terms top of stack is argument transfer area for arguments
 983 # which could not be accommodated in registers. Or in other words 7th
 984 # [integer] argument resides at 8(%rsp) upon function entry point.
 985 # 128 bytes above %rsp constitute a "red zone" which is not touched
 986 # by signal handlers and can be used as temporal storage without
 987 # allocating a frame.
 988 #
 989 # In Win64 terms N*8 bytes on top of stack is argument transfer area,
 990 # which belongs to/can be overwritten by callee. N is the number of
 991 # arguments passed to callee, *but* not less than 4! This means that
 992 # upon function entry point 5th argument resides at 40(%rsp), as well
 993 # as that 32 bytes from 8(%rsp) can always be used as temporal
 994 # storage [without allocating a frame]. One can actually argue that
 995 # one can assume a "red zone" above stack pointer under Win64 as well.
 996 # Point is that at apparently no occasion Windows kernel would alter
 997 # the area above user stack pointer in true asynchronous manner...
 998 #
 999 # All the above means that if assembler programmer adheres to Unix
1000 # register and stack layout, but disregards the "red zone" existense,
1001 # it's possible to use following prologue and epilogue to "gear" from
1002 # Unix to Win64 ABI in leaf functions with not more than 6 arguments.
1003 #
1004 # omnipotent_function:
1005 # ifdef WIN64
1006 #       movq    %rdi,8(%rsp)
1007 #       movq    %rsi,16(%rsp)
1008 #       movq    %rcx,%rdi       ; if 1st argument is actually present
1009 #       movq    %rdx,%rsi       ; if 2nd argument is actually ...
1010 #       movq    %r8,%rdx        ; if 3rd argument is ...
1011 #       movq    %r9,%rcx        ; if 4th argument ...
1012 #       movq    40(%rsp),%r8    ; if 5th ...
1013 #       movq    48(%rsp),%r9    ; if 6th ...
1014 # endif
1015 #       ...
1016 # ifdef WIN64
1017 #       movq    8(%rsp),%rdi
1018 #       movq    16(%rsp),%rsi
1019 # endif
1020 #       ret
1021 #
1022 \f#################################################
1023 # Win64 SEH, Structured Exception Handling.
1024 #
1025 # Unlike on Unix systems(*) lack of Win64 stack unwinding information
1026 # has undesired side-effect at run-time: if an exception is raised in
1027 # assembler subroutine such as those in question (basically we're
1028 # referring to segmentation violations caused by malformed input
1029 # parameters), the application is briskly terminated without invoking
1030 # any exception handlers, most notably without generating memory dump
1031 # or any user notification whatsoever. This poses a problem. It's
1032 # possible to address it by registering custom language-specific
1033 # handler that would restore processor context to the state at
1034 # subroutine entry point and return "exception is not handled, keep
1035 # unwinding" code. Writing such handler can be a challenge... But it's
1036 # doable, though requires certain coding convention. Consider following
1037 # snippet:
1038 #
1039 # .type function,@function
1040 # function:
1041 #       movq    %rsp,%rax       # copy rsp to volatile register
1042 #       pushq   %r15            # save non-volatile registers
1043 #       pushq   %rbx
1044 #       pushq   %rbp
1045 #       movq    %rsp,%r11
1046 #       subq    %rdi,%r11       # prepare [variable] stack frame
1047 #       andq    $-64,%r11
1048 #       movq    %rax,0(%r11)    # check for exceptions
1049 #       movq    %r11,%rsp       # allocate [variable] stack frame
1050 #       movq    %rax,0(%rsp)    # save original rsp value
1051 # magic_point:
1052 #       ...
1053 #       movq    0(%rsp),%rcx    # pull original rsp value
1054 #       movq    -24(%rcx),%rbp  # restore non-volatile registers
1055 #       movq    -16(%rcx),%rbx
1056 #       movq    -8(%rcx),%r15
1057 #       movq    %rcx,%rsp       # restore original rsp
1058 #       ret
1059 # .size function,.-function
1060 #
1061 # The key is that up to magic_point copy of original rsp value remains
1062 # in chosen volatile register and no non-volatile register, except for
1063 # rsp, is modified. While past magic_point rsp remains constant till
1064 # the very end of the function. In this case custom language-specific
1065 # exception handler would look like this:
1066 #
1067 # EXCEPTION_DISPOSITION handler (EXCEPTION_RECORD *rec,ULONG64 frame,
1068 #               CONTEXT *context,DISPATCHER_CONTEXT *disp)
1069 # {     ULONG64 *rsp = (ULONG64 *)context->Rax;
1070 #       if (context->Rip >= magic_point)
1071 #       {   rsp = ((ULONG64 **)context->Rsp)[0];
1072 #           context->Rbp = rsp[-3];
1073 #           context->Rbx = rsp[-2];
1074 #           context->R15 = rsp[-1];
1075 #       }
1076 #       context->Rsp = (ULONG64)rsp;
1077 #       context->Rdi = rsp[1];
1078 #       context->Rsi = rsp[2];
1079 #
1080 #       memcpy (disp->ContextRecord,context,sizeof(CONTEXT));
1081 #       RtlVirtualUnwind(UNW_FLAG_NHANDLER,disp->ImageBase,
1082 #               dips->ControlPc,disp->FunctionEntry,disp->ContextRecord,
1083 #               &disp->HandlerData,&disp->EstablisherFrame,NULL);
1084 #       return ExceptionContinueSearch;
1085 # }
1086 #
1087 # It's appropriate to implement this handler in assembler, directly in
1088 # function's module. In order to do that one has to know members'
1089 # offsets in CONTEXT and DISPATCHER_CONTEXT structures and some constant
1090 # values. Here they are:
1091 #
1092 #       CONTEXT.Rax                             120
1093 #       CONTEXT.Rcx                             128
1094 #       CONTEXT.Rdx                             136
1095 #       CONTEXT.Rbx                             144
1096 #       CONTEXT.Rsp                             152
1097 #       CONTEXT.Rbp                             160
1098 #       CONTEXT.Rsi                             168
1099 #       CONTEXT.Rdi                             176
1100 #       CONTEXT.R8                              184
1101 #       CONTEXT.R9                              192
1102 #       CONTEXT.R10                             200
1103 #       CONTEXT.R11                             208
1104 #       CONTEXT.R12                             216
1105 #       CONTEXT.R13                             224
1106 #       CONTEXT.R14                             232
1107 #       CONTEXT.R15                             240
1108 #       CONTEXT.Rip                             248
1109 #       CONTEXT.Xmm6                            512
1110 #       sizeof(CONTEXT)                         1232
1111 #       DISPATCHER_CONTEXT.ControlPc            0
1112 #       DISPATCHER_CONTEXT.ImageBase            8
1113 #       DISPATCHER_CONTEXT.FunctionEntry        16
1114 #       DISPATCHER_CONTEXT.EstablisherFrame     24
1115 #       DISPATCHER_CONTEXT.TargetIp             32
1116 #       DISPATCHER_CONTEXT.ContextRecord        40
1117 #       DISPATCHER_CONTEXT.LanguageHandler      48
1118 #       DISPATCHER_CONTEXT.HandlerData          56
1119 #       UNW_FLAG_NHANDLER                       0
1120 #       ExceptionContinueSearch                 1
1121 #
1122 # In order to tie the handler to the function one has to compose
1123 # couple of structures: one for .xdata segment and one for .pdata.
1124 #
1125 # UNWIND_INFO structure for .xdata segment would be
1126 #
1127 # function_unwind_info:
1128 #       .byte   9,0,0,0
1129 #       .rva    handler
1130 #
1131 # This structure designates exception handler for a function with
1132 # zero-length prologue, no stack frame or frame register.
1133 #
1134 # To facilitate composing of .pdata structures, auto-generated "gear"
1135 # prologue copies rsp value to rax and denotes next instruction with
1136 # .LSEH_begin_{function_name} label. This essentially defines the SEH
1137 # styling rule mentioned in the beginning. Position of this label is
1138 # chosen in such manner that possible exceptions raised in the "gear"
1139 # prologue would be accounted to caller and unwound from latter's frame.
1140 # End of function is marked with respective .LSEH_end_{function_name}
1141 # label. To summarize, .pdata segment would contain
1142 #
1143 #       .rva    .LSEH_begin_function
1144 #       .rva    .LSEH_end_function
1145 #       .rva    function_unwind_info
1146 #
1147 # Reference to function_unwind_info from .xdata segment is the anchor.
1148 # In case you wonder why references are 32-bit .rvas and not 64-bit
1149 # .quads. References put into these two segments are required to be
1150 # *relative* to the base address of the current binary module, a.k.a.
1151 # image base. No Win64 module, be it .exe or .dll, can be larger than
1152 # 2GB and thus such relative references can be and are accommodated in
1153 # 32 bits.
1154 #
1155 # Having reviewed the example function code, one can argue that "movq
1156 # %rsp,%rax" above is redundant. It is not! Keep in mind that on Unix
1157 # rax would contain an undefined value. If this "offends" you, use
1158 # another register and refrain from modifying rax till magic_point is
1159 # reached, i.e. as if it was a non-volatile register. If more registers
1160 # are required prior [variable] frame setup is completed, note that
1161 # nobody says that you can have only one "magic point." You can
1162 # "liberate" non-volatile registers by denoting last stack off-load
1163 # instruction and reflecting it in finer grade unwind logic in handler.
1164 # After all, isn't it why it's called *language-specific* handler...
1165 #
1166 # Attentive reader can notice that exceptions would be mishandled in
1167 # auto-generated "gear" epilogue. Well, exception effectively can't
1168 # occur there, because if memory area used by it was subject to
1169 # segmentation violation, then it would be raised upon call to the
1170 # function (and as already mentioned be accounted to caller, which is
1171 # not a problem). If you're still not comfortable, then define tail
1172 # "magic point" just prior ret instruction and have handler treat it...
1173 #
1174 # (*)   Note that we're talking about run-time, not debug-time. Lack of
1175 #       unwind information makes debugging hard on both Windows and
1176 #       Unix. "Unlike" referes to the fact that on Unix signal handler
1177 #       will always be invoked, core dumped and appropriate exit code
1178 #       returned to parent (for user notification).