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. 55# 56# 8. In order to provide for structured exception handling unified 57# Win64 prologue copies %rsp value to %rax. For further details 58# see SEH paragraph at the end. 59# 9. .init segment is allowed to contain calls to functions only. 60# a. If function accepts more than 4 arguments *and* >4th argument 61# is declared as non 64-bit value, do clear its upper part. 62 63 64use strict; 65 66my $flavour = shift; 67my $output = shift; 68if ($flavour =~ /\./) { $output = $flavour; undef $flavour; } 69 70open STDOUT,">$output" || die "can't open $output: $!" 71 if (defined($output)); 72 73my $gas=1; $gas=0 if ($output =~ /\.asm$/); 74my $elf=1; $elf=0 if (!$gas); 75my $win64=0; 76my $prefix=""; 77my $decor=".L"; 78 79my $masmref=8 + 50727*2**-32; # 8.00.50727 shipped with VS2005 80my $masm=0; 81my $PTR=" PTR"; 82 83my $nasmref=2.03; 84my $nasm=0; 85 86if ($flavour eq "mingw64") { $gas=1; $elf=0; $win64=1; 87 # TODO(davidben): Before supporting the 88 # mingw64 perlasm flavour, do away with this 89 # environment variable check. 90 die "mingw64 not supported"; 91 $prefix=`echo __USER_LABEL_PREFIX__ | $ENV{CC} -E -P -`; 92 $prefix =~ s|\R$||; # Better chomp 93 } 94elsif ($flavour eq "macosx") { $gas=1; $elf=0; $prefix="_"; $decor="L\$"; } 95elsif ($flavour eq "masm") { $gas=0; $elf=0; $masm=$masmref; $win64=1; $decor="\$L\$"; } 96elsif ($flavour eq "nasm") { $gas=0; $elf=0; $nasm=$nasmref; $win64=1; $decor="\$L\$"; $PTR=""; } 97elsif (!$gas) { die "unknown flavour $flavour"; } 98 99my $current_segment; 100my $current_function; 101my %globals; 102 103{ package opcode; # pick up opcodes 104 sub re { 105 my ($class, $line) = @_; 106 my $self = {}; 107 my $ret; 108 109 if ($$line =~ /^([a-z][a-z0-9]*)/i) { 110 bless $self,$class; 111 $self->{op} = $1; 112 $ret = $self; 113 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; 114 115 undef $self->{sz}; 116 if ($self->{op} =~ /^(movz)x?([bw]).*/) { # movz is pain... 117 $self->{op} = $1; 118 $self->{sz} = $2; 119 } elsif ($self->{op} =~ /call|jmp/) { 120 $self->{sz} = ""; 121 } elsif ($self->{op} =~ /^p/ && $' !~ /^(ush|op|insrw)/) { # SSEn 122 $self->{sz} = ""; 123 } elsif ($self->{op} =~ /^[vk]/) { # VEX or k* such as kmov 124 $self->{sz} = ""; 125 } elsif ($self->{op} =~ /mov[dq]/ && $$line =~ /%xmm/) { 126 $self->{sz} = ""; 127 } elsif ($self->{op} =~ /([a-z]{3,})([qlwb])$/) { 128 $self->{op} = $1; 129 $self->{sz} = $2; 130 } 131 } 132 $ret; 133 } 134 sub size { 135 my ($self, $sz) = @_; 136 $self->{sz} = $sz if (defined($sz) && !defined($self->{sz})); 137 $self->{sz}; 138 } 139 sub out { 140 my $self = shift; 141 if ($gas) { 142 if ($self->{op} eq "movz") { # movz is pain... 143 sprintf "%s%s%s",$self->{op},$self->{sz},shift; 144 } elsif ($self->{op} =~ /^set/) { 145 "$self->{op}"; 146 } elsif ($self->{op} eq "ret") { 147 my $epilogue = ""; 148 if ($win64 && $current_function->{abi} eq "svr4") { 149 $epilogue = "movq 8(%rsp),%rdi\n\t" . 150 "movq 16(%rsp),%rsi\n\t"; 151 } 152 $epilogue . ".byte 0xf3,0xc3"; 153 } elsif ($self->{op} eq "call" && !$elf && $current_segment eq ".init") { 154 ".p2align\t3\n\t.quad"; 155 } else { 156 "$self->{op}$self->{sz}"; 157 } 158 } else { 159 $self->{op} =~ s/^movz/movzx/; 160 if ($self->{op} eq "ret") { 161 $self->{op} = ""; 162 if ($win64 && $current_function->{abi} eq "svr4") { 163 $self->{op} = "mov rdi,QWORD$PTR\[8+rsp\]\t;WIN64 epilogue\n\t". 164 "mov rsi,QWORD$PTR\[16+rsp\]\n\t"; 165 } 166 $self->{op} .= "DB\t0F3h,0C3h\t\t;repret"; 167 } elsif ($self->{op} =~ /^(pop|push)f/) { 168 $self->{op} .= $self->{sz}; 169 } elsif ($self->{op} eq "call" && $current_segment eq ".CRT\$XCU") { 170 $self->{op} = "\tDQ"; 171 } 172 $self->{op}; 173 } 174 } 175 sub mnemonic { 176 my ($self, $op) = @_; 177 $self->{op}=$op if (defined($op)); 178 $self->{op}; 179 } 180} 181{ package const; # pick up constants, which start with $ 182 sub re { 183 my ($class, $line) = @_; 184 my $self = {}; 185 my $ret; 186 187 if ($$line =~ /^\$([^,]+)/) { 188 bless $self, $class; 189 $self->{value} = $1; 190 $ret = $self; 191 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; 192 } 193 $ret; 194 } 195 sub out { 196 my $self = shift; 197 198 $self->{value} =~ s/\b(0b[0-1]+)/oct($1)/eig; 199 if ($gas) { 200 # Solaris /usr/ccs/bin/as can't handle multiplications 201 # in $self->{value} 202 my $value = $self->{value}; 203 no warnings; # oct might complain about overflow, ignore here... 204 $value =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi; 205 if ($value =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg) { 206 $self->{value} = $value; 207 } 208 sprintf "\$%s",$self->{value}; 209 } else { 210 my $value = $self->{value}; 211 $value =~ s/0x([0-9a-f]+)/0$1h/ig if ($masm); 212 sprintf "%s",$value; 213 } 214 } 215} 216{ package ea; # pick up effective addresses: expr(%reg,%reg,scale) 217 218 my %szmap = ( b=>"BYTE$PTR", w=>"WORD$PTR", 219 l=>"DWORD$PTR", d=>"DWORD$PTR", 220 q=>"QWORD$PTR", o=>"OWORD$PTR", 221 x=>"XMMWORD$PTR", y=>"YMMWORD$PTR", 222 z=>"ZMMWORD$PTR" ) if (!$gas); 223 224 sub re { 225 my ($class, $line, $opcode) = @_; 226 my $self = {}; 227 my $ret; 228 229 # optional * ----vvv--- appears in indirect jmp/call 230 if ($$line =~ /^(\*?)([^\(,]*)\(([%\w,]+)\)((?:{[^}]+})*)/) { 231 bless $self, $class; 232 $self->{asterisk} = $1; 233 $self->{label} = $2; 234 ($self->{base},$self->{index},$self->{scale})=split(/,/,$3); 235 $self->{scale} = 1 if (!defined($self->{scale})); 236 $self->{opmask} = $4; 237 $ret = $self; 238 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; 239 240 if ($win64 && $self->{label} =~ s/\@GOTPCREL//) { 241 die if ($opcode->mnemonic() ne "mov"); 242 $opcode->mnemonic("lea"); 243 } 244 $self->{base} =~ s/^%//; 245 $self->{index} =~ s/^%// if (defined($self->{index})); 246 $self->{opcode} = $opcode; 247 } 248 $ret; 249 } 250 sub size {} 251 sub out { 252 my ($self, $sz) = @_; 253 254 $self->{label} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei; 255 $self->{label} =~ s/\.L/$decor/g; 256 257 # Silently convert all EAs to 64-bit. This is required for 258 # elder GNU assembler and results in more compact code, 259 # *but* most importantly AES module depends on this feature! 260 $self->{index} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/; 261 $self->{base} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/; 262 263 # Solaris /usr/ccs/bin/as can't handle multiplications 264 # in $self->{label}... 265 use integer; 266 $self->{label} =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi; 267 $self->{label} =~ s/\b([0-9]+\s*[\*\/\%]\s*[0-9]+)\b/eval($1)/eg; 268 269 # Some assemblers insist on signed presentation of 32-bit 270 # offsets, but sign extension is a tricky business in perl... 271 if ((1<<31)<<1) { 272 $self->{label} =~ s/\b([0-9]+)\b/$1<<32>>32/eg; 273 } else { 274 $self->{label} =~ s/\b([0-9]+)\b/$1>>0/eg; 275 } 276 277 # if base register is %rbp or %r13, see if it's possible to 278 # flip base and index registers [for better performance] 279 if (!$self->{label} && $self->{index} && $self->{scale}==1 && 280 $self->{base} =~ /(rbp|r13)/) { 281 $self->{base} = $self->{index}; $self->{index} = $1; 282 } 283 284 if ($gas) { 285 $self->{label} =~ s/^___imp_/__imp__/ if ($flavour eq "mingw64"); 286 287 if (defined($self->{index})) { 288 sprintf "%s%s(%s,%%%s,%d)%s", 289 $self->{asterisk},$self->{label}, 290 $self->{base}?"%$self->{base}":"", 291 $self->{index},$self->{scale}, 292 $self->{opmask}; 293 } else { 294 sprintf "%s%s(%%%s)%s", $self->{asterisk},$self->{label}, 295 $self->{base},$self->{opmask}; 296 } 297 } else { 298 $self->{label} =~ s/\./\$/g; 299 $self->{label} =~ s/(?<![\w\$\.])0x([0-9a-f]+)/0$1h/ig; 300 $self->{label} = "($self->{label})" if ($self->{label} =~ /[\*\+\-\/]/); 301 302 my $mnemonic = $self->{opcode}->mnemonic(); 303 ($self->{asterisk}) && ($sz="q") || 304 ($mnemonic =~ /^v?mov([qd])$/) && ($sz=$1) || 305 ($mnemonic =~ /^v?pinsr([qdwb])$/) && ($sz=$1) || 306 ($mnemonic =~ /^vpbroadcast([qdwb])$/) && ($sz=$1) || 307 ($mnemonic =~ /^v(?!perm)[a-z]+[fi]128$/) && ($sz="x"); 308 309 $self->{opmask} =~ s/%(k[0-7])/$1/; 310 311 if (defined($self->{index})) { 312 sprintf "%s[%s%s*%d%s]%s",$szmap{$sz}, 313 $self->{label}?"$self->{label}+":"", 314 $self->{index},$self->{scale}, 315 $self->{base}?"+$self->{base}":"", 316 $self->{opmask}; 317 } elsif ($self->{base} eq "rip") { 318 sprintf "%s[%s]",$szmap{$sz},$self->{label}; 319 } else { 320 sprintf "%s[%s%s]%s", $szmap{$sz}, 321 $self->{label}?"$self->{label}+":"", 322 $self->{base},$self->{opmask}; 323 } 324 } 325 } 326} 327{ package register; # pick up registers, which start with %. 328 sub re { 329 my ($class, $line, $opcode) = @_; 330 my $self = {}; 331 my $ret; 332 333 # optional * ----vvv--- appears in indirect jmp/call 334 if ($$line =~ /^(\*?)%(\w+)((?:{[^}]+})*)/) { 335 bless $self,$class; 336 $self->{asterisk} = $1; 337 $self->{value} = $2; 338 $self->{opmask} = $3; 339 $opcode->size($self->size()); 340 $ret = $self; 341 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; 342 } 343 $ret; 344 } 345 sub size { 346 my $self = shift; 347 my $ret; 348 349 if ($self->{value} =~ /^r[\d]+b$/i) { $ret="b"; } 350 elsif ($self->{value} =~ /^r[\d]+w$/i) { $ret="w"; } 351 elsif ($self->{value} =~ /^r[\d]+d$/i) { $ret="l"; } 352 elsif ($self->{value} =~ /^r[\w]+$/i) { $ret="q"; } 353 elsif ($self->{value} =~ /^[a-d][hl]$/i){ $ret="b"; } 354 elsif ($self->{value} =~ /^[\w]{2}l$/i) { $ret="b"; } 355 elsif ($self->{value} =~ /^[\w]{2}$/i) { $ret="w"; } 356 elsif ($self->{value} =~ /^e[a-z]{2}$/i){ $ret="l"; } 357 358 $ret; 359 } 360 sub out { 361 my $self = shift; 362 if ($gas) { sprintf "%s%%%s%s", $self->{asterisk}, 363 $self->{value}, 364 $self->{opmask}; } 365 else { $self->{opmask} =~ s/%(k[0-7])/$1/; 366 $self->{value}.$self->{opmask}; } 367 } 368} 369{ package label; # pick up labels, which end with : 370 sub re { 371 my ($class, $line) = @_; 372 my $self = {}; 373 my $ret; 374 375 if ($$line =~ /(^[\.\w]+)\:/) { 376 bless $self,$class; 377 $self->{value} = $1; 378 $ret = $self; 379 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; 380 381 $self->{value} =~ s/^\.L/$decor/; 382 } 383 $ret; 384 } 385 sub out { 386 my $self = shift; 387 388 if ($gas) { 389 my $func = ($globals{$self->{value}} or $self->{value}) . ":"; 390 if ($win64 && $current_function->{name} eq $self->{value} 391 && $current_function->{abi} eq "svr4") { 392 $func .= "\n"; 393 $func .= " movq %rdi,8(%rsp)\n"; 394 $func .= " movq %rsi,16(%rsp)\n"; 395 $func .= " movq %rsp,%rax\n"; 396 $func .= "${decor}SEH_begin_$current_function->{name}:\n"; 397 my $narg = $current_function->{narg}; 398 $narg=6 if (!defined($narg)); 399 $func .= " movq %rcx,%rdi\n" if ($narg>0); 400 $func .= " movq %rdx,%rsi\n" if ($narg>1); 401 $func .= " movq %r8,%rdx\n" if ($narg>2); 402 $func .= " movq %r9,%rcx\n" if ($narg>3); 403 $func .= " movq 40(%rsp),%r8\n" if ($narg>4); 404 $func .= " movq 48(%rsp),%r9\n" if ($narg>5); 405 } 406 $func; 407 } elsif ($self->{value} ne "$current_function->{name}") { 408 # Make all labels in masm global. 409 $self->{value} .= ":" if ($masm); 410 $self->{value} . ":"; 411 } elsif ($win64 && $current_function->{abi} eq "svr4") { 412 my $func = "$current_function->{name}" . 413 ($nasm ? ":" : "\tPROC $current_function->{scope}") . 414 "\n"; 415 $func .= " mov QWORD$PTR\[8+rsp\],rdi\t;WIN64 prologue\n"; 416 $func .= " mov QWORD$PTR\[16+rsp\],rsi\n"; 417 $func .= " mov rax,rsp\n"; 418 $func .= "${decor}SEH_begin_$current_function->{name}:"; 419 $func .= ":" if ($masm); 420 $func .= "\n"; 421 my $narg = $current_function->{narg}; 422 $narg=6 if (!defined($narg)); 423 $func .= " mov rdi,rcx\n" if ($narg>0); 424 $func .= " mov rsi,rdx\n" if ($narg>1); 425 $func .= " mov rdx,r8\n" if ($narg>2); 426 $func .= " mov rcx,r9\n" if ($narg>3); 427 $func .= " mov r8,QWORD$PTR\[40+rsp\]\n" if ($narg>4); 428 $func .= " mov r9,QWORD$PTR\[48+rsp\]\n" if ($narg>5); 429 $func .= "\n"; 430 } else { 431 "$current_function->{name}". 432 ($nasm ? ":" : "\tPROC $current_function->{scope}"); 433 } 434 } 435} 436{ package expr; # pick up expressions 437 sub re { 438 my ($class, $line, $opcode) = @_; 439 my $self = {}; 440 my $ret; 441 442 if ($$line =~ /(^[^,]+)/) { 443 bless $self,$class; 444 $self->{value} = $1; 445 $ret = $self; 446 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; 447 448 $self->{value} =~ s/\@PLT// if (!$elf); 449 $self->{value} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei; 450 $self->{value} =~ s/\.L/$decor/g; 451 $self->{opcode} = $opcode; 452 } 453 $ret; 454 } 455 sub out { 456 my $self = shift; 457 if ($nasm && $self->{opcode}->mnemonic()=~m/^j(?![re]cxz)/) { 458 "NEAR ".$self->{value}; 459 } else { 460 $self->{value}; 461 } 462 } 463} 464{ package cfi_directive; 465 # CFI directives annotate instructions that are significant for 466 # stack unwinding procedure compliant with DWARF specification, 467 # see http://dwarfstd.org/. Besides naturally expected for this 468 # script platform-specific filtering function, this module adds 469 # three auxiliary synthetic directives not recognized by [GNU] 470 # assembler: 471 # 472 # - .cfi_push to annotate push instructions in prologue, which 473 # translates to .cfi_adjust_cfa_offset (if needed) and 474 # .cfi_offset; 475 # - .cfi_pop to annotate pop instructions in epilogue, which 476 # translates to .cfi_adjust_cfa_offset (if needed) and 477 # .cfi_restore; 478 # - [and most notably] .cfi_cfa_expression which encodes 479 # DW_CFA_def_cfa_expression and passes it to .cfi_escape as 480 # byte vector; 481 # 482 # CFA expressions were introduced in DWARF specification version 483 # 3 and describe how to deduce CFA, Canonical Frame Address. This 484 # becomes handy if your stack frame is variable and you can't 485 # spare register for [previous] frame pointer. Suggested directive 486 # syntax is made-up mix of DWARF operator suffixes [subset of] 487 # and references to registers with optional bias. Following example 488 # describes offloaded *original* stack pointer at specific offset 489 # from *current* stack pointer: 490 # 491 # .cfi_cfa_expression %rsp+40,deref,+8 492 # 493 # Final +8 has everything to do with the fact that CFA is defined 494 # as reference to top of caller's stack, and on x86_64 call to 495 # subroutine pushes 8-byte return address. In other words original 496 # stack pointer upon entry to a subroutine is 8 bytes off from CFA. 497 498 # Below constants are taken from "DWARF Expressions" section of the 499 # DWARF specification, section is numbered 7.7 in versions 3 and 4. 500 my %DW_OP_simple = ( # no-arg operators, mapped directly 501 deref => 0x06, dup => 0x12, 502 drop => 0x13, over => 0x14, 503 pick => 0x15, swap => 0x16, 504 rot => 0x17, xderef => 0x18, 505 506 abs => 0x19, and => 0x1a, 507 div => 0x1b, minus => 0x1c, 508 mod => 0x1d, mul => 0x1e, 509 neg => 0x1f, not => 0x20, 510 or => 0x21, plus => 0x22, 511 shl => 0x24, shr => 0x25, 512 shra => 0x26, xor => 0x27, 513 ); 514 515 my %DW_OP_complex = ( # used in specific subroutines 516 constu => 0x10, # uleb128 517 consts => 0x11, # sleb128 518 plus_uconst => 0x23, # uleb128 519 lit0 => 0x30, # add 0-31 to opcode 520 reg0 => 0x50, # add 0-31 to opcode 521 breg0 => 0x70, # add 0-31 to opcole, sleb128 522 regx => 0x90, # uleb28 523 fbreg => 0x91, # sleb128 524 bregx => 0x92, # uleb128, sleb128 525 piece => 0x93, # uleb128 526 ); 527 528 # Following constants are defined in x86_64 ABI supplement, for 529 # example avaiable at https://www.uclibc.org/docs/psABI-x86_64.pdf, 530 # see section 3.7 "Stack Unwind Algorithm". 531 my %DW_reg_idx = ( 532 "%rax"=>0, "%rdx"=>1, "%rcx"=>2, "%rbx"=>3, 533 "%rsi"=>4, "%rdi"=>5, "%rbp"=>6, "%rsp"=>7, 534 "%r8" =>8, "%r9" =>9, "%r10"=>10, "%r11"=>11, 535 "%r12"=>12, "%r13"=>13, "%r14"=>14, "%r15"=>15 536 ); 537 538 my ($cfa_reg, $cfa_rsp); 539 540 # [us]leb128 format is variable-length integer representation base 541 # 2^128, with most significant bit of each byte being 0 denoting 542 # *last* most significat digit. See "Variable Length Data" in the 543 # DWARF specification, numbered 7.6 at least in versions 3 and 4. 544 sub sleb128 { 545 use integer; # get right shift extend sign 546 547 my $val = shift; 548 my $sign = ($val < 0) ? -1 : 0; 549 my @ret = (); 550 551 while(1) { 552 push @ret, $val&0x7f; 553 554 # see if remaining bits are same and equal to most 555 # significant bit of the current digit, if so, it's 556 # last digit... 557 last if (($val>>6) == $sign); 558 559 @ret[-1] |= 0x80; 560 $val >>= 7; 561 } 562 563 return @ret; 564 } 565 sub uleb128 { 566 my $val = shift; 567 my @ret = (); 568 569 while(1) { 570 push @ret, $val&0x7f; 571 572 # see if it's last significant digit... 573 last if (($val >>= 7) == 0); 574 575 @ret[-1] |= 0x80; 576 } 577 578 return @ret; 579 } 580 sub const { 581 my $val = shift; 582 583 if ($val >= 0 && $val < 32) { 584 return ($DW_OP_complex{lit0}+$val); 585 } 586 return ($DW_OP_complex{consts}, sleb128($val)); 587 } 588 sub reg { 589 my $val = shift; 590 591 return if ($val !~ m/^(%r\w+)(?:([\+\-])((?:0x)?[0-9a-f]+))?/); 592 593 my $reg = $DW_reg_idx{$1}; 594 my $off = eval ("0 $2 $3"); 595 596 return (($DW_OP_complex{breg0} + $reg), sleb128($off)); 597 # Yes, we use DW_OP_bregX+0 to push register value and not 598 # DW_OP_regX, because latter would require even DW_OP_piece, 599 # which would be a waste under the circumstances. If you have 600 # to use DWP_OP_reg, use "regx:N"... 601 } 602 sub cfa_expression { 603 my $line = shift; 604 my @ret; 605 606 foreach my $token (split(/,\s*/,$line)) { 607 if ($token =~ /^%r/) { 608 push @ret,reg($token); 609 } elsif ($token =~ /((?:0x)?[0-9a-f]+)\((%r\w+)\)/) { 610 push @ret,reg("$2+$1"); 611 } elsif ($token =~ /(\w+):(\-?(?:0x)?[0-9a-f]+)(U?)/i) { 612 my $i = 1*eval($2); 613 push @ret,$DW_OP_complex{$1}, ($3 ? uleb128($i) : sleb128($i)); 614 } elsif (my $i = 1*eval($token) or $token eq "0") { 615 if ($token =~ /^\+/) { 616 push @ret,$DW_OP_complex{plus_uconst},uleb128($i); 617 } else { 618 push @ret,const($i); 619 } 620 } else { 621 push @ret,$DW_OP_simple{$token}; 622 } 623 } 624 625 # Finally we return DW_CFA_def_cfa_expression, 15, followed by 626 # length of the expression and of course the expression itself. 627 return (15,scalar(@ret),@ret); 628 } 629 sub re { 630 my ($class, $line) = @_; 631 my $self = {}; 632 my $ret; 633 634 if ($$line =~ s/^\s*\.cfi_(\w+)\s*//) { 635 bless $self,$class; 636 $ret = $self; 637 undef $self->{value}; 638 my $dir = $1; 639 640 SWITCH: for ($dir) { 641 # What is $cfa_rsp? Effectively it's difference between %rsp 642 # value and current CFA, Canonical Frame Address, which is 643 # why it starts with -8. Recall that CFA is top of caller's 644 # stack... 645 /startproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", -8); last; }; 646 /endproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", 0); last; }; 647 /def_cfa_register/ 648 && do { $cfa_reg = $$line; last; }; 649 /def_cfa_offset/ 650 && do { $cfa_rsp = -1*eval($$line) if ($cfa_reg eq "%rsp"); 651 last; 652 }; 653 /adjust_cfa_offset/ 654 && do { $cfa_rsp -= 1*eval($$line) if ($cfa_reg eq "%rsp"); 655 last; 656 }; 657 /def_cfa/ && do { if ($$line =~ /(%r\w+)\s*,\s*(.+)/) { 658 $cfa_reg = $1; 659 $cfa_rsp = -1*eval($2) if ($cfa_reg eq "%rsp"); 660 } 661 last; 662 }; 663 /push/ && do { $dir = undef; 664 $cfa_rsp -= 8; 665 if ($cfa_reg eq "%rsp") { 666 $self->{value} = ".cfi_adjust_cfa_offset\t8\n"; 667 } 668 $self->{value} .= ".cfi_offset\t$$line,$cfa_rsp"; 669 last; 670 }; 671 /pop/ && do { $dir = undef; 672 $cfa_rsp += 8; 673 if ($cfa_reg eq "%rsp") { 674 $self->{value} = ".cfi_adjust_cfa_offset\t-8\n"; 675 } 676 $self->{value} .= ".cfi_restore\t$$line"; 677 last; 678 }; 679 /cfa_expression/ 680 && do { $dir = undef; 681 $self->{value} = ".cfi_escape\t" . 682 join(",", map(sprintf("0x%02x", $_), 683 cfa_expression($$line))); 684 last; 685 }; 686 } 687 688 $self->{value} = ".cfi_$dir\t$$line" if ($dir); 689 690 $$line = ""; 691 } 692 693 return $ret; 694 } 695 sub out { 696 my $self = shift; 697 return ($elf ? $self->{value} : undef); 698 } 699} 700{ package directive; # pick up directives, which start with . 701 sub re { 702 my ($class, $line) = @_; 703 my $self = {}; 704 my $ret; 705 my $dir; 706 707 # chain-call to cfi_directive 708 $ret = cfi_directive->re($line) and return $ret; 709 710 if ($$line =~ /^\s*(\.\w+)/) { 711 bless $self,$class; 712 $dir = $1; 713 $ret = $self; 714 undef $self->{value}; 715 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; 716 717 SWITCH: for ($dir) { 718 /\.global|\.globl|\.extern/ 719 && do { $globals{$$line} = $prefix . $$line; 720 $$line = $globals{$$line} if ($prefix); 721 last; 722 }; 723 /\.type/ && do { my ($sym,$type,$narg) = split(',',$$line); 724 if ($type eq "\@function") { 725 undef $current_function; 726 $current_function->{name} = $sym; 727 $current_function->{abi} = "svr4"; 728 $current_function->{narg} = $narg; 729 $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE"; 730 } elsif ($type eq "\@abi-omnipotent") { 731 undef $current_function; 732 $current_function->{name} = $sym; 733 $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE"; 734 } 735 $$line =~ s/\@abi\-omnipotent/\@function/; 736 $$line =~ s/\@function.*/\@function/; 737 last; 738 }; 739 /\.asciz/ && do { if ($$line =~ /^"(.*)"$/) { 740 $dir = ".byte"; 741 $$line = join(",",unpack("C*",$1),0); 742 } 743 last; 744 }; 745 /\.rva|\.long|\.quad/ 746 && do { $$line =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei; 747 $$line =~ s/\.L/$decor/g; 748 last; 749 }; 750 } 751 752 if ($gas) { 753 $self->{value} = $dir . "\t" . $$line; 754 755 if ($dir =~ /\.extern/) { 756 if ($flavour eq "elf") { 757 $self->{value} .= "\n.hidden $$line"; 758 } else { 759 $self->{value} = ""; 760 } 761 } elsif (!$elf && $dir =~ /\.type/) { 762 $self->{value} = ""; 763 $self->{value} = ".def\t" . ($globals{$1} or $1) . ";\t" . 764 (defined($globals{$1})?".scl 2;":".scl 3;") . 765 "\t.type 32;\t.endef" 766 if ($win64 && $$line =~ /([^,]+),\@function/); 767 } elsif (!$elf && $dir =~ /\.size/) { 768 $self->{value} = ""; 769 if (defined($current_function)) { 770 $self->{value} .= "${decor}SEH_end_$current_function->{name}:" 771 if ($win64 && $current_function->{abi} eq "svr4"); 772 undef $current_function; 773 } 774 } elsif (!$elf && $dir =~ /\.align/) { 775 $self->{value} = ".p2align\t" . (log($$line)/log(2)); 776 } elsif ($dir eq ".section") { 777 $current_segment=$$line; 778 if (!$elf && $current_segment eq ".init") { 779 if ($flavour eq "macosx") { $self->{value} = ".mod_init_func"; } 780 elsif ($flavour eq "mingw64") { $self->{value} = ".section\t.ctors"; } 781 } 782 } elsif ($dir =~ /\.(text|data)/) { 783 $current_segment=".$1"; 784 } elsif ($dir =~ /\.global|\.globl|\.extern/) { 785 if ($flavour eq "macosx") { 786 $self->{value} .= "\n.private_extern $$line"; 787 } else { 788 $self->{value} .= "\n.hidden $$line"; 789 } 790 } elsif ($dir =~ /\.hidden/) { 791 if ($flavour eq "macosx") { $self->{value} = ".private_extern\t$prefix$$line"; } 792 elsif ($flavour eq "mingw64") { $self->{value} = ""; } 793 } elsif ($dir =~ /\.comm/) { 794 $self->{value} = "$dir\t$prefix$$line"; 795 $self->{value} =~ s|,([0-9]+),([0-9]+)$|",$1,".log($2)/log(2)|e if ($flavour eq "macosx"); 796 } 797 $$line = ""; 798 return $self; 799 } 800 801 # non-gas case or nasm/masm 802 SWITCH: for ($dir) { 803 /\.text/ && do { my $v=undef; 804 if ($nasm) { 805 $v="section .text code align=64\n"; 806 } else { 807 $v="$current_segment\tENDS\n" if ($current_segment); 808 $current_segment = ".text\$"; 809 $v.="$current_segment\tSEGMENT "; 810 $v.=$masm>=$masmref ? "ALIGN(256)" : "PAGE"; 811 $v.=" 'CODE'"; 812 } 813 $self->{value} = $v; 814 last; 815 }; 816 /\.data/ && do { my $v=undef; 817 if ($nasm) { 818 $v="section .data data align=8\n"; 819 } else { 820 $v="$current_segment\tENDS\n" if ($current_segment); 821 $current_segment = "_DATA"; 822 $v.="$current_segment\tSEGMENT"; 823 } 824 $self->{value} = $v; 825 last; 826 }; 827 /\.section/ && do { my $v=undef; 828 $$line =~ s/([^,]*).*/$1/; 829 $$line = ".CRT\$XCU" if ($$line eq ".init"); 830 if ($nasm) { 831 $v="section $$line"; 832 if ($$line=~/\.([px])data/) { 833 $v.=" rdata align="; 834 $v.=$1 eq "p"? 4 : 8; 835 } elsif ($$line=~/\.CRT\$/i) { 836 $v.=" rdata align=8"; 837 } 838 } else { 839 $v="$current_segment\tENDS\n" if ($current_segment); 840 $v.="$$line\tSEGMENT"; 841 if ($$line=~/\.([px])data/) { 842 $v.=" READONLY"; 843 $v.=" ALIGN(".($1 eq "p" ? 4 : 8).")" if ($masm>=$masmref); 844 } elsif ($$line=~/\.CRT\$/i) { 845 $v.=" READONLY "; 846 $v.=$masm>=$masmref ? "ALIGN(8)" : "DWORD"; 847 } 848 } 849 $current_segment = $$line; 850 $self->{value} = $v; 851 last; 852 }; 853 /\.extern/ && do { $self->{value} = "EXTERN\t".$$line; 854 $self->{value} .= ":NEAR" if ($masm); 855 last; 856 }; 857 /\.globl|.global/ 858 && do { $self->{value} = $masm?"PUBLIC":"global"; 859 $self->{value} .= "\t".$$line; 860 last; 861 }; 862 /\.size/ && do { if (defined($current_function)) { 863 undef $self->{value}; 864 if ($current_function->{abi} eq "svr4") { 865 $self->{value}="${decor}SEH_end_$current_function->{name}:"; 866 $self->{value}.=":\n" if($masm); 867 } 868 $self->{value}.="$current_function->{name}\tENDP" if($masm && $current_function->{name}); 869 undef $current_function; 870 } 871 last; 872 }; 873 /\.align/ && do { my $max = ($masm && $masm>=$masmref) ? 256 : 4096; 874 $self->{value} = "ALIGN\t".($$line>$max?$max:$$line); 875 last; 876 }; 877 /\.(value|long|rva|quad)/ 878 && do { my $sz = substr($1,0,1); 879 my @arr = split(/,\s*/,$$line); 880 my $last = pop(@arr); 881 my $conv = sub { my $var=shift; 882 $var=~s/^(0b[0-1]+)/oct($1)/eig; 883 $var=~s/^0x([0-9a-f]+)/0$1h/ig if ($masm); 884 if ($sz eq "D" && ($current_segment=~/.[px]data/ || $dir eq ".rva")) 885 { $var=~s/([_a-z\$\@][_a-z0-9\$\@]*)/$nasm?"$1 wrt ..imagebase":"imagerel $1"/egi; } 886 $var; 887 }; 888 889 $sz =~ tr/bvlrq/BWDDQ/; 890 $self->{value} = "\tD$sz\t"; 891 for (@arr) { $self->{value} .= &$conv($_).","; } 892 $self->{value} .= &$conv($last); 893 last; 894 }; 895 /\.byte/ && do { my @str=split(/,\s*/,$$line); 896 map(s/(0b[0-1]+)/oct($1)/eig,@str); 897 map(s/0x([0-9a-f]+)/0$1h/ig,@str) if ($masm); 898 while ($#str>15) { 899 $self->{value}.="DB\t" 900 .join(",",@str[0..15])."\n"; 901 foreach (0..15) { shift @str; } 902 } 903 $self->{value}.="DB\t" 904 .join(",",@str) if (@str); 905 last; 906 }; 907 /\.comm/ && do { my @str=split(/,\s*/,$$line); 908 my $v=undef; 909 if ($nasm) { 910 $v.="common $prefix@str[0] @str[1]"; 911 } else { 912 $v="$current_segment\tENDS\n" if ($current_segment); 913 $current_segment = "_DATA"; 914 $v.="$current_segment\tSEGMENT\n"; 915 $v.="COMM @str[0]:DWORD:".@str[1]/4; 916 } 917 $self->{value} = $v; 918 last; 919 }; 920 } 921 $$line = ""; 922 } 923 924 $ret; 925 } 926 sub out { 927 my $self = shift; 928 $self->{value}; 929 } 930} 931 932# Upon initial x86_64 introduction SSE>2 extensions were not introduced 933# yet. In order not to be bothered by tracing exact assembler versions, 934# but at the same time to provide a bare security minimum of AES-NI, we 935# hard-code some instructions. Extensions past AES-NI on the other hand 936# are traced by examining assembler version in individual perlasm 937# modules... 938 939my %regrm = ( "%eax"=>0, "%ecx"=>1, "%edx"=>2, "%ebx"=>3, 940 "%esp"=>4, "%ebp"=>5, "%esi"=>6, "%edi"=>7 ); 941 942sub rex { 943 my $opcode=shift; 944 my ($dst,$src,$rex)=@_; 945 946 $rex|=0x04 if($dst>=8); 947 $rex|=0x01 if($src>=8); 948 push @$opcode,($rex|0x40) if ($rex); 949} 950 951my $movq = sub { # elderly gas can't handle inter-register movq 952 my $arg = shift; 953 my @opcode=(0x66); 954 if ($arg =~ /%xmm([0-9]+),\s*%r(\w+)/) { 955 my ($src,$dst)=($1,$2); 956 if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; } 957 rex(\@opcode,$src,$dst,0x8); 958 push @opcode,0x0f,0x7e; 959 push @opcode,0xc0|(($src&7)<<3)|($dst&7); # ModR/M 960 @opcode; 961 } elsif ($arg =~ /%r(\w+),\s*%xmm([0-9]+)/) { 962 my ($src,$dst)=($2,$1); 963 if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; } 964 rex(\@opcode,$src,$dst,0x8); 965 push @opcode,0x0f,0x6e; 966 push @opcode,0xc0|(($src&7)<<3)|($dst&7); # ModR/M 967 @opcode; 968 } else { 969 (); 970 } 971}; 972 973my $pextrd = sub { 974 if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*(%\w+)/) { 975 my @opcode=(0x66); 976 my $imm=$1; 977 my $src=$2; 978 my $dst=$3; 979 if ($dst =~ /%r([0-9]+)d/) { $dst = $1; } 980 elsif ($dst =~ /%e/) { $dst = $regrm{$dst}; } 981 rex(\@opcode,$src,$dst); 982 push @opcode,0x0f,0x3a,0x16; 983 push @opcode,0xc0|(($src&7)<<3)|($dst&7); # ModR/M 984 push @opcode,$imm; 985 @opcode; 986 } else { 987 (); 988 } 989}; 990 991my $pinsrd = sub { 992 if (shift =~ /\$([0-9]+),\s*(%\w+),\s*%xmm([0-9]+)/) { 993 my @opcode=(0x66); 994 my $imm=$1; 995 my $src=$2; 996 my $dst=$3; 997 if ($src =~ /%r([0-9]+)/) { $src = $1; } 998 elsif ($src =~ /%e/) { $src = $regrm{$src}; } 999 rex(\@opcode,$dst,$src); 1000 push @opcode,0x0f,0x3a,0x22; 1001 push @opcode,0xc0|(($dst&7)<<3)|($src&7); # ModR/M 1002 push @opcode,$imm; 1003 @opcode; 1004 } else { 1005 (); 1006 } 1007}; 1008 1009my $pshufb = sub { 1010 if (shift =~ /%xmm([0-9]+),\s*%xmm([0-9]+)/) { 1011 my @opcode=(0x66); 1012 rex(\@opcode,$2,$1); 1013 push @opcode,0x0f,0x38,0x00; 1014 push @opcode,0xc0|($1&7)|(($2&7)<<3); # ModR/M 1015 @opcode; 1016 } else { 1017 (); 1018 } 1019}; 1020 1021my $palignr = sub { 1022 if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) { 1023 my @opcode=(0x66); 1024 rex(\@opcode,$3,$2); 1025 push @opcode,0x0f,0x3a,0x0f; 1026 push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M 1027 push @opcode,$1; 1028 @opcode; 1029 } else { 1030 (); 1031 } 1032}; 1033 1034my $pclmulqdq = sub { 1035 if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) { 1036 my @opcode=(0x66); 1037 rex(\@opcode,$3,$2); 1038 push @opcode,0x0f,0x3a,0x44; 1039 push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M 1040 my $c=$1; 1041 push @opcode,$c=~/^0/?oct($c):$c; 1042 @opcode; 1043 } else { 1044 (); 1045 } 1046}; 1047 1048my $rdrand = sub { 1049 if (shift =~ /%[er](\w+)/) { 1050 my @opcode=(); 1051 my $dst=$1; 1052 if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; } 1053 rex(\@opcode,0,$dst,8); 1054 push @opcode,0x0f,0xc7,0xf0|($dst&7); 1055 @opcode; 1056 } else { 1057 (); 1058 } 1059}; 1060 1061my $rdseed = sub { 1062 if (shift =~ /%[er](\w+)/) { 1063 my @opcode=(); 1064 my $dst=$1; 1065 if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; } 1066 rex(\@opcode,0,$dst,8); 1067 push @opcode,0x0f,0xc7,0xf8|($dst&7); 1068 @opcode; 1069 } else { 1070 (); 1071 } 1072}; 1073 1074# Not all AVX-capable assemblers recognize AMD XOP extension. Since we 1075# are using only two instructions hand-code them in order to be excused 1076# from chasing assembler versions... 1077 1078sub rxb { 1079 my $opcode=shift; 1080 my ($dst,$src1,$src2,$rxb)=@_; 1081 1082 $rxb|=0x7<<5; 1083 $rxb&=~(0x04<<5) if($dst>=8); 1084 $rxb&=~(0x01<<5) if($src1>=8); 1085 $rxb&=~(0x02<<5) if($src2>=8); 1086 push @$opcode,$rxb; 1087} 1088 1089my $vprotd = sub { 1090 if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) { 1091 my @opcode=(0x8f); 1092 rxb(\@opcode,$3,$2,-1,0x08); 1093 push @opcode,0x78,0xc2; 1094 push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M 1095 my $c=$1; 1096 push @opcode,$c=~/^0/?oct($c):$c; 1097 @opcode; 1098 } else { 1099 (); 1100 } 1101}; 1102 1103my $vprotq = sub { 1104 if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) { 1105 my @opcode=(0x8f); 1106 rxb(\@opcode,$3,$2,-1,0x08); 1107 push @opcode,0x78,0xc3; 1108 push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M 1109 my $c=$1; 1110 push @opcode,$c=~/^0/?oct($c):$c; 1111 @opcode; 1112 } else { 1113 (); 1114 } 1115}; 1116 1117# Intel Control-flow Enforcement Technology extension. All functions and 1118# indirect branch targets will have to start with this instruction... 1119 1120my $endbranch = sub { 1121 (0xf3,0x0f,0x1e,0xfa); 1122}; 1123 1124######################################################################## 1125 1126if ($nasm) { 1127 print <<___; 1128default rel 1129%define XMMWORD 1130%define YMMWORD 1131%define ZMMWORD 1132___ 1133} elsif ($masm) { 1134 print <<___; 1135OPTION DOTNAME 1136___ 1137} 1138print STDOUT "#if defined(__x86_64__) && !defined(OPENSSL_NO_ASM)\n" if ($gas); 1139 1140while(defined(my $line=<>)) { 1141 1142 $line =~ s|\R$||; # Better chomp 1143 1144 $line =~ s|[#!].*$||; # get rid of asm-style comments... 1145 $line =~ s|/\*.*\*/||; # ... and C-style comments... 1146 $line =~ s|^\s+||; # ... and skip white spaces in beginning 1147 $line =~ s|\s+$||; # ... and at the end 1148 1149 if (my $label=label->re(\$line)) { print $label->out(); } 1150 1151 if (my $directive=directive->re(\$line)) { 1152 printf "%s",$directive->out(); 1153 } elsif (my $opcode=opcode->re(\$line)) { 1154 my $asm = eval("\$".$opcode->mnemonic()); 1155 1156 if ((ref($asm) eq 'CODE') && scalar(my @bytes=&$asm($line))) { 1157 print $gas?".byte\t":"DB\t",join(',',@bytes),"\n"; 1158 next; 1159 } 1160 1161 my @args; 1162 ARGUMENT: while (1) { 1163 my $arg; 1164 1165 ($arg=register->re(\$line, $opcode))|| 1166 ($arg=const->re(\$line)) || 1167 ($arg=ea->re(\$line, $opcode)) || 1168 ($arg=expr->re(\$line, $opcode)) || 1169 last ARGUMENT; 1170 1171 push @args,$arg; 1172 1173 last ARGUMENT if ($line !~ /^,/); 1174 1175 $line =~ s/^,\s*//; 1176 } # ARGUMENT: 1177 1178 if ($#args>=0) { 1179 my $insn; 1180 my $sz=$opcode->size(); 1181 1182 if ($gas) { 1183 $insn = $opcode->out($#args>=1?$args[$#args]->size():$sz); 1184 @args = map($_->out($sz),@args); 1185 printf "\t%s\t%s",$insn,join(",",@args); 1186 } else { 1187 $insn = $opcode->out(); 1188 foreach (@args) { 1189 my $arg = $_->out(); 1190 # $insn.=$sz compensates for movq, pinsrw, ... 1191 if ($arg =~ /^xmm[0-9]+$/) { $insn.=$sz; $sz="x" if(!$sz); last; } 1192 if ($arg =~ /^ymm[0-9]+$/) { $insn.=$sz; $sz="y" if(!$sz); last; } 1193 if ($arg =~ /^zmm[0-9]+$/) { $insn.=$sz; $sz="z" if(!$sz); last; } 1194 if ($arg =~ /^mm[0-9]+$/) { $insn.=$sz; $sz="q" if(!$sz); last; } 1195 } 1196 @args = reverse(@args); 1197 undef $sz if ($nasm && $opcode->mnemonic() eq "lea"); 1198 printf "\t%s\t%s",$insn,join(",",map($_->out($sz),@args)); 1199 } 1200 } else { 1201 printf "\t%s",$opcode->out(); 1202 } 1203 } 1204 1205 print $line,"\n"; 1206} 1207 1208print "\n$current_segment\tENDS\n" if ($current_segment && $masm); 1209print "END\n" if ($masm); 1210print "#endif\n" if ($gas); 1211 1212 1213close STDOUT; 1214 1215 ################################################# 1216# Cross-reference x86_64 ABI "card" 1217# 1218# Unix Win64 1219# %rax * * 1220# %rbx - - 1221# %rcx #4 #1 1222# %rdx #3 #2 1223# %rsi #2 - 1224# %rdi #1 - 1225# %rbp - - 1226# %rsp - - 1227# %r8 #5 #3 1228# %r9 #6 #4 1229# %r10 * * 1230# %r11 * * 1231# %r12 - - 1232# %r13 - - 1233# %r14 - - 1234# %r15 - - 1235# 1236# (*) volatile register 1237# (-) preserved by callee 1238# (#) Nth argument, volatile 1239# 1240# In Unix terms top of stack is argument transfer area for arguments 1241# which could not be accommodated in registers. Or in other words 7th 1242# [integer] argument resides at 8(%rsp) upon function entry point. 1243# 128 bytes above %rsp constitute a "red zone" which is not touched 1244# by signal handlers and can be used as temporal storage without 1245# allocating a frame. 1246# 1247# In Win64 terms N*8 bytes on top of stack is argument transfer area, 1248# which belongs to/can be overwritten by callee. N is the number of 1249# arguments passed to callee, *but* not less than 4! This means that 1250# upon function entry point 5th argument resides at 40(%rsp), as well 1251# as that 32 bytes from 8(%rsp) can always be used as temporal 1252# storage [without allocating a frame]. One can actually argue that 1253# one can assume a "red zone" above stack pointer under Win64 as well. 1254# Point is that at apparently no occasion Windows kernel would alter 1255# the area above user stack pointer in true asynchronous manner... 1256# 1257# All the above means that if assembler programmer adheres to Unix 1258# register and stack layout, but disregards the "red zone" existence, 1259# it's possible to use following prologue and epilogue to "gear" from 1260# Unix to Win64 ABI in leaf functions with not more than 6 arguments. 1261# 1262# omnipotent_function: 1263# ifdef WIN64 1264# movq %rdi,8(%rsp) 1265# movq %rsi,16(%rsp) 1266# movq %rcx,%rdi ; if 1st argument is actually present 1267# movq %rdx,%rsi ; if 2nd argument is actually ... 1268# movq %r8,%rdx ; if 3rd argument is ... 1269# movq %r9,%rcx ; if 4th argument ... 1270# movq 40(%rsp),%r8 ; if 5th ... 1271# movq 48(%rsp),%r9 ; if 6th ... 1272# endif 1273# ... 1274# ifdef WIN64 1275# movq 8(%rsp),%rdi 1276# movq 16(%rsp),%rsi 1277# endif 1278# ret 1279# 1280 ################################################# 1281# Win64 SEH, Structured Exception Handling. 1282# 1283# Unlike on Unix systems(*) lack of Win64 stack unwinding information 1284# has undesired side-effect at run-time: if an exception is raised in 1285# assembler subroutine such as those in question (basically we're 1286# referring to segmentation violations caused by malformed input 1287# parameters), the application is briskly terminated without invoking 1288# any exception handlers, most notably without generating memory dump 1289# or any user notification whatsoever. This poses a problem. It's 1290# possible to address it by registering custom language-specific 1291# handler that would restore processor context to the state at 1292# subroutine entry point and return "exception is not handled, keep 1293# unwinding" code. Writing such handler can be a challenge... But it's 1294# doable, though requires certain coding convention. Consider following 1295# snippet: 1296# 1297# .type function,@function 1298# function: 1299# movq %rsp,%rax # copy rsp to volatile register 1300# pushq %r15 # save non-volatile registers 1301# pushq %rbx 1302# pushq %rbp 1303# movq %rsp,%r11 1304# subq %rdi,%r11 # prepare [variable] stack frame 1305# andq $-64,%r11 1306# movq %rax,0(%r11) # check for exceptions 1307# movq %r11,%rsp # allocate [variable] stack frame 1308# movq %rax,0(%rsp) # save original rsp value 1309# magic_point: 1310# ... 1311# movq 0(%rsp),%rcx # pull original rsp value 1312# movq -24(%rcx),%rbp # restore non-volatile registers 1313# movq -16(%rcx),%rbx 1314# movq -8(%rcx),%r15 1315# movq %rcx,%rsp # restore original rsp 1316# magic_epilogue: 1317# ret 1318# .size function,.-function 1319# 1320# The key is that up to magic_point copy of original rsp value remains 1321# in chosen volatile register and no non-volatile register, except for 1322# rsp, is modified. While past magic_point rsp remains constant till 1323# the very end of the function. In this case custom language-specific 1324# exception handler would look like this: 1325# 1326# EXCEPTION_DISPOSITION handler (EXCEPTION_RECORD *rec,ULONG64 frame, 1327# CONTEXT *context,DISPATCHER_CONTEXT *disp) 1328# { ULONG64 *rsp = (ULONG64 *)context->Rax; 1329# ULONG64 rip = context->Rip; 1330# 1331# if (rip >= magic_point) 1332# { rsp = (ULONG64 *)context->Rsp; 1333# if (rip < magic_epilogue) 1334# { rsp = (ULONG64 *)rsp[0]; 1335# context->Rbp = rsp[-3]; 1336# context->Rbx = rsp[-2]; 1337# context->R15 = rsp[-1]; 1338# } 1339# } 1340# context->Rsp = (ULONG64)rsp; 1341# context->Rdi = rsp[1]; 1342# context->Rsi = rsp[2]; 1343# 1344# memcpy (disp->ContextRecord,context,sizeof(CONTEXT)); 1345# RtlVirtualUnwind(UNW_FLAG_NHANDLER,disp->ImageBase, 1346# dips->ControlPc,disp->FunctionEntry,disp->ContextRecord, 1347# &disp->HandlerData,&disp->EstablisherFrame,NULL); 1348# return ExceptionContinueSearch; 1349# } 1350# 1351# It's appropriate to implement this handler in assembler, directly in 1352# function's module. In order to do that one has to know members' 1353# offsets in CONTEXT and DISPATCHER_CONTEXT structures and some constant 1354# values. Here they are: 1355# 1356# CONTEXT.Rax 120 1357# CONTEXT.Rcx 128 1358# CONTEXT.Rdx 136 1359# CONTEXT.Rbx 144 1360# CONTEXT.Rsp 152 1361# CONTEXT.Rbp 160 1362# CONTEXT.Rsi 168 1363# CONTEXT.Rdi 176 1364# CONTEXT.R8 184 1365# CONTEXT.R9 192 1366# CONTEXT.R10 200 1367# CONTEXT.R11 208 1368# CONTEXT.R12 216 1369# CONTEXT.R13 224 1370# CONTEXT.R14 232 1371# CONTEXT.R15 240 1372# CONTEXT.Rip 248 1373# CONTEXT.Xmm6 512 1374# sizeof(CONTEXT) 1232 1375# DISPATCHER_CONTEXT.ControlPc 0 1376# DISPATCHER_CONTEXT.ImageBase 8 1377# DISPATCHER_CONTEXT.FunctionEntry 16 1378# DISPATCHER_CONTEXT.EstablisherFrame 24 1379# DISPATCHER_CONTEXT.TargetIp 32 1380# DISPATCHER_CONTEXT.ContextRecord 40 1381# DISPATCHER_CONTEXT.LanguageHandler 48 1382# DISPATCHER_CONTEXT.HandlerData 56 1383# UNW_FLAG_NHANDLER 0 1384# ExceptionContinueSearch 1 1385# 1386# In order to tie the handler to the function one has to compose 1387# couple of structures: one for .xdata segment and one for .pdata. 1388# 1389# UNWIND_INFO structure for .xdata segment would be 1390# 1391# function_unwind_info: 1392# .byte 9,0,0,0 1393# .rva handler 1394# 1395# This structure designates exception handler for a function with 1396# zero-length prologue, no stack frame or frame register. 1397# 1398# To facilitate composing of .pdata structures, auto-generated "gear" 1399# prologue copies rsp value to rax and denotes next instruction with 1400# .LSEH_begin_{function_name} label. This essentially defines the SEH 1401# styling rule mentioned in the beginning. Position of this label is 1402# chosen in such manner that possible exceptions raised in the "gear" 1403# prologue would be accounted to caller and unwound from latter's frame. 1404# End of function is marked with respective .LSEH_end_{function_name} 1405# label. To summarize, .pdata segment would contain 1406# 1407# .rva .LSEH_begin_function 1408# .rva .LSEH_end_function 1409# .rva function_unwind_info 1410# 1411# Reference to function_unwind_info from .xdata segment is the anchor. 1412# In case you wonder why references are 32-bit .rvas and not 64-bit 1413# .quads. References put into these two segments are required to be 1414# *relative* to the base address of the current binary module, a.k.a. 1415# image base. No Win64 module, be it .exe or .dll, can be larger than 1416# 2GB and thus such relative references can be and are accommodated in 1417# 32 bits. 1418# 1419# Having reviewed the example function code, one can argue that "movq 1420# %rsp,%rax" above is redundant. It is not! Keep in mind that on Unix 1421# rax would contain an undefined value. If this "offends" you, use 1422# another register and refrain from modifying rax till magic_point is 1423# reached, i.e. as if it was a non-volatile register. If more registers 1424# are required prior [variable] frame setup is completed, note that 1425# nobody says that you can have only one "magic point." You can 1426# "liberate" non-volatile registers by denoting last stack off-load 1427# instruction and reflecting it in finer grade unwind logic in handler. 1428# After all, isn't it why it's called *language-specific* handler... 1429# 1430# SE handlers are also involved in unwinding stack when executable is 1431# profiled or debugged. Profiling implies additional limitations that 1432# are too subtle to discuss here. For now it's sufficient to say that 1433# in order to simplify handlers one should either a) offload original 1434# %rsp to stack (like discussed above); or b) if you have a register to 1435# spare for frame pointer, choose volatile one. 1436# 1437# (*) Note that we're talking about run-time, not debug-time. Lack of 1438# unwind information makes debugging hard on both Windows and 1439# Unix. "Unlike" referes to the fact that on Unix signal handler 1440# will always be invoked, core dumped and appropriate exit code 1441# returned to parent (for user notification). 1442