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Many spelling fixes/typo's corrected.
[thirdparty/openssl.git] / 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.
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 \f
63
64 use strict;
65
66 my $flavour = shift;
67 my $output = shift;
68 if ($flavour =~ /\./) { $output = $flavour; undef $flavour; }
69
70 open STDOUT,">$output" || die "can't open $output: $!"
71 if (defined($output));
72
73 my $gas=1; $gas=0 if ($output =~ /\.asm$/);
74 my $elf=1; $elf=0 if (!$gas);
75 my $win64=0;
76 my $prefix="";
77 my $decor=".L";
78
79 my $masmref=8 + 50727*2**-32; # 8.00.50727 shipped with VS2005
80 my $masm=0;
81 my $PTR=" PTR";
82
83 my $nasmref=2.03;
84 my $nasm=0;
85
86 if ($flavour eq "mingw64") { $gas=1; $elf=0; $win64=1;
87 $prefix=`echo __USER_LABEL_PREFIX__ | $ENV{CC} -E -P -`;
88 $prefix =~ s|\R$||; # Better chomp
89 }
90 elsif ($flavour eq "macosx") { $gas=1; $elf=0; $prefix="_"; $decor="L\$"; }
91 elsif ($flavour eq "masm") { $gas=0; $elf=0; $masm=$masmref; $win64=1; $decor="\$L\$"; }
92 elsif ($flavour eq "nasm") { $gas=0; $elf=0; $nasm=$nasmref; $win64=1; $decor="\$L\$"; $PTR=""; }
93 elsif (!$gas)
94 { if ($ENV{ASM} =~ m/nasm/ && `nasm -v` =~ m/version ([0-9]+)\.([0-9]+)/i)
95 { $nasm = $1 + $2*0.01; $PTR=""; }
96 elsif (`ml64 2>&1` =~ m/Version ([0-9]+)\.([0-9]+)(\.([0-9]+))?/)
97 { $masm = $1 + $2*2**-16 + $4*2**-32; }
98 die "no assembler found on %PATH%" if (!($nasm || $masm));
99 $win64=1;
100 $elf=0;
101 $decor="\$L\$";
102 }
103
104 my $current_segment;
105 my $current_function;
106 my %globals;
107
108 { package opcode; # pick up opcodes
109 sub re {
110 my ($class, $line) = @_;
111 my $self = {};
112 my $ret;
113
114 if ($$line =~ /^([a-z][a-z0-9]*)/i) {
115 bless $self,$class;
116 $self->{op} = $1;
117 $ret = $self;
118 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
119
120 undef $self->{sz};
121 if ($self->{op} =~ /^(movz)x?([bw]).*/) { # movz is pain...
122 $self->{op} = $1;
123 $self->{sz} = $2;
124 } elsif ($self->{op} =~ /call|jmp/) {
125 $self->{sz} = "";
126 } elsif ($self->{op} =~ /^p/ && $' !~ /^(ush|op|insrw)/) { # SSEn
127 $self->{sz} = "";
128 } elsif ($self->{op} =~ /^[vk]/) { # VEX or k* such as kmov
129 $self->{sz} = "";
130 } elsif ($self->{op} =~ /mov[dq]/ && $$line =~ /%xmm/) {
131 $self->{sz} = "";
132 } elsif ($self->{op} =~ /([a-z]{3,})([qlwb])$/) {
133 $self->{op} = $1;
134 $self->{sz} = $2;
135 }
136 }
137 $ret;
138 }
139 sub size {
140 my ($self, $sz) = @_;
141 $self->{sz} = $sz if (defined($sz) && !defined($self->{sz}));
142 $self->{sz};
143 }
144 sub out {
145 my $self = shift;
146 if ($gas) {
147 if ($self->{op} eq "movz") { # movz is pain...
148 sprintf "%s%s%s",$self->{op},$self->{sz},shift;
149 } elsif ($self->{op} =~ /^set/) {
150 "$self->{op}";
151 } elsif ($self->{op} eq "ret") {
152 my $epilogue = "";
153 if ($win64 && $current_function->{abi} eq "svr4") {
154 $epilogue = "movq 8(%rsp),%rdi\n\t" .
155 "movq 16(%rsp),%rsi\n\t";
156 }
157 $epilogue . ".byte 0xf3,0xc3";
158 } elsif ($self->{op} eq "call" && !$elf && $current_segment eq ".init") {
159 ".p2align\t3\n\t.quad";
160 } else {
161 "$self->{op}$self->{sz}";
162 }
163 } else {
164 $self->{op} =~ s/^movz/movzx/;
165 if ($self->{op} eq "ret") {
166 $self->{op} = "";
167 if ($win64 && $current_function->{abi} eq "svr4") {
168 $self->{op} = "mov rdi,QWORD$PTR\[8+rsp\]\t;WIN64 epilogue\n\t".
169 "mov rsi,QWORD$PTR\[16+rsp\]\n\t";
170 }
171 $self->{op} .= "DB\t0F3h,0C3h\t\t;repret";
172 } elsif ($self->{op} =~ /^(pop|push)f/) {
173 $self->{op} .= $self->{sz};
174 } elsif ($self->{op} eq "call" && $current_segment eq ".CRT\$XCU") {
175 $self->{op} = "\tDQ";
176 }
177 $self->{op};
178 }
179 }
180 sub mnemonic {
181 my ($self, $op) = @_;
182 $self->{op}=$op if (defined($op));
183 $self->{op};
184 }
185 }
186 { package const; # pick up constants, which start with $
187 sub re {
188 my ($class, $line) = @_;
189 my $self = {};
190 my $ret;
191
192 if ($$line =~ /^\$([^,]+)/) {
193 bless $self, $class;
194 $self->{value} = $1;
195 $ret = $self;
196 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
197 }
198 $ret;
199 }
200 sub out {
201 my $self = shift;
202
203 $self->{value} =~ s/\b(0b[0-1]+)/oct($1)/eig;
204 if ($gas) {
205 # Solaris /usr/ccs/bin/as can't handle multiplications
206 # in $self->{value}
207 my $value = $self->{value};
208 no warnings; # oct might complain about overflow, ignore here...
209 $value =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi;
210 if ($value =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg) {
211 $self->{value} = $value;
212 }
213 sprintf "\$%s",$self->{value};
214 } else {
215 my $value = $self->{value};
216 $value =~ s/0x([0-9a-f]+)/0$1h/ig if ($masm);
217 sprintf "%s",$value;
218 }
219 }
220 }
221 { package ea; # pick up effective addresses: expr(%reg,%reg,scale)
222
223 my %szmap = ( b=>"BYTE$PTR", w=>"WORD$PTR",
224 l=>"DWORD$PTR", d=>"DWORD$PTR",
225 q=>"QWORD$PTR", o=>"OWORD$PTR",
226 x=>"XMMWORD$PTR", y=>"YMMWORD$PTR",
227 z=>"ZMMWORD$PTR" ) if (!$gas);
228
229 sub re {
230 my ($class, $line, $opcode) = @_;
231 my $self = {};
232 my $ret;
233
234 # optional * ----vvv--- appears in indirect jmp/call
235 if ($$line =~ /^(\*?)([^\(,]*)\(([%\w,]+)\)((?:{[^}]+})*)/) {
236 bless $self, $class;
237 $self->{asterisk} = $1;
238 $self->{label} = $2;
239 ($self->{base},$self->{index},$self->{scale})=split(/,/,$3);
240 $self->{scale} = 1 if (!defined($self->{scale}));
241 $self->{opmask} = $4;
242 $ret = $self;
243 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
244
245 if ($win64 && $self->{label} =~ s/\@GOTPCREL//) {
246 die if ($opcode->mnemonic() ne "mov");
247 $opcode->mnemonic("lea");
248 }
249 $self->{base} =~ s/^%//;
250 $self->{index} =~ s/^%// if (defined($self->{index}));
251 $self->{opcode} = $opcode;
252 }
253 $ret;
254 }
255 sub size {}
256 sub out {
257 my ($self, $sz) = @_;
258
259 $self->{label} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
260 $self->{label} =~ s/\.L/$decor/g;
261
262 # Silently convert all EAs to 64-bit. This is required for
263 # elder GNU assembler and results in more compact code,
264 # *but* most importantly AES module depends on this feature!
265 $self->{index} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/;
266 $self->{base} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/;
267
268 # Solaris /usr/ccs/bin/as can't handle multiplications
269 # in $self->{label}...
270 use integer;
271 $self->{label} =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi;
272 $self->{label} =~ s/\b([0-9]+\s*[\*\/\%]\s*[0-9]+)\b/eval($1)/eg;
273
274 # Some assemblers insist on signed presentation of 32-bit
275 # offsets, but sign extension is a tricky business in perl...
276 if ((1<<31)<<1) {
277 $self->{label} =~ s/\b([0-9]+)\b/$1<<32>>32/eg;
278 } else {
279 $self->{label} =~ s/\b([0-9]+)\b/$1>>0/eg;
280 }
281
282 # if base register is %rbp or %r13, see if it's possible to
283 # flip base and index registers [for better performance]
284 if (!$self->{label} && $self->{index} && $self->{scale}==1 &&
285 $self->{base} =~ /(rbp|r13)/) {
286 $self->{base} = $self->{index}; $self->{index} = $1;
287 }
288
289 if ($gas) {
290 $self->{label} =~ s/^___imp_/__imp__/ if ($flavour eq "mingw64");
291
292 if (defined($self->{index})) {
293 sprintf "%s%s(%s,%%%s,%d)%s",
294 $self->{asterisk},$self->{label},
295 $self->{base}?"%$self->{base}":"",
296 $self->{index},$self->{scale},
297 $self->{opmask};
298 } else {
299 sprintf "%s%s(%%%s)%s", $self->{asterisk},$self->{label},
300 $self->{base},$self->{opmask};
301 }
302 } else {
303 $self->{label} =~ s/\./\$/g;
304 $self->{label} =~ s/(?<![\w\$\.])0x([0-9a-f]+)/0$1h/ig;
305 $self->{label} = "($self->{label})" if ($self->{label} =~ /[\*\+\-\/]/);
306
307 my $mnemonic = $self->{opcode}->mnemonic();
308 ($self->{asterisk}) && ($sz="q") ||
309 ($mnemonic =~ /^v?mov([qd])$/) && ($sz=$1) ||
310 ($mnemonic =~ /^v?pinsr([qdwb])$/) && ($sz=$1) ||
311 ($mnemonic =~ /^vpbroadcast([qdwb])$/) && ($sz=$1) ||
312 ($mnemonic =~ /^v(?!perm)[a-z]+[fi]128$/) && ($sz="x");
313
314 $self->{opmask} =~ s/%(k[0-7])/$1/;
315
316 if (defined($self->{index})) {
317 sprintf "%s[%s%s*%d%s]%s",$szmap{$sz},
318 $self->{label}?"$self->{label}+":"",
319 $self->{index},$self->{scale},
320 $self->{base}?"+$self->{base}":"",
321 $self->{opmask};
322 } elsif ($self->{base} eq "rip") {
323 sprintf "%s[%s]",$szmap{$sz},$self->{label};
324 } else {
325 sprintf "%s[%s%s]%s", $szmap{$sz},
326 $self->{label}?"$self->{label}+":"",
327 $self->{base},$self->{opmask};
328 }
329 }
330 }
331 }
332 { package register; # pick up registers, which start with %.
333 sub re {
334 my ($class, $line, $opcode) = @_;
335 my $self = {};
336 my $ret;
337
338 # optional * ----vvv--- appears in indirect jmp/call
339 if ($$line =~ /^(\*?)%(\w+)((?:{[^}]+})*)/) {
340 bless $self,$class;
341 $self->{asterisk} = $1;
342 $self->{value} = $2;
343 $self->{opmask} = $3;
344 $opcode->size($self->size());
345 $ret = $self;
346 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
347 }
348 $ret;
349 }
350 sub size {
351 my $self = shift;
352 my $ret;
353
354 if ($self->{value} =~ /^r[\d]+b$/i) { $ret="b"; }
355 elsif ($self->{value} =~ /^r[\d]+w$/i) { $ret="w"; }
356 elsif ($self->{value} =~ /^r[\d]+d$/i) { $ret="l"; }
357 elsif ($self->{value} =~ /^r[\w]+$/i) { $ret="q"; }
358 elsif ($self->{value} =~ /^[a-d][hl]$/i){ $ret="b"; }
359 elsif ($self->{value} =~ /^[\w]{2}l$/i) { $ret="b"; }
360 elsif ($self->{value} =~ /^[\w]{2}$/i) { $ret="w"; }
361 elsif ($self->{value} =~ /^e[a-z]{2}$/i){ $ret="l"; }
362
363 $ret;
364 }
365 sub out {
366 my $self = shift;
367 if ($gas) { sprintf "%s%%%s%s", $self->{asterisk},
368 $self->{value},
369 $self->{opmask}; }
370 else { $self->{opmask} =~ s/%(k[0-7])/$1/;
371 $self->{value}.$self->{opmask}; }
372 }
373 }
374 { package label; # pick up labels, which end with :
375 sub re {
376 my ($class, $line) = @_;
377 my $self = {};
378 my $ret;
379
380 if ($$line =~ /(^[\.\w]+)\:/) {
381 bless $self,$class;
382 $self->{value} = $1;
383 $ret = $self;
384 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
385
386 $self->{value} =~ s/^\.L/$decor/;
387 }
388 $ret;
389 }
390 sub out {
391 my $self = shift;
392
393 if ($gas) {
394 my $func = ($globals{$self->{value}} or $self->{value}) . ":";
395 if ($win64 && $current_function->{name} eq $self->{value}
396 && $current_function->{abi} eq "svr4") {
397 $func .= "\n";
398 $func .= " movq %rdi,8(%rsp)\n";
399 $func .= " movq %rsi,16(%rsp)\n";
400 $func .= " movq %rsp,%rax\n";
401 $func .= "${decor}SEH_begin_$current_function->{name}:\n";
402 my $narg = $current_function->{narg};
403 $narg=6 if (!defined($narg));
404 $func .= " movq %rcx,%rdi\n" if ($narg>0);
405 $func .= " movq %rdx,%rsi\n" if ($narg>1);
406 $func .= " movq %r8,%rdx\n" if ($narg>2);
407 $func .= " movq %r9,%rcx\n" if ($narg>3);
408 $func .= " movq 40(%rsp),%r8\n" if ($narg>4);
409 $func .= " movq 48(%rsp),%r9\n" if ($narg>5);
410 }
411 $func;
412 } elsif ($self->{value} ne "$current_function->{name}") {
413 # Make all labels in masm global.
414 $self->{value} .= ":" if ($masm);
415 $self->{value} . ":";
416 } elsif ($win64 && $current_function->{abi} eq "svr4") {
417 my $func = "$current_function->{name}" .
418 ($nasm ? ":" : "\tPROC $current_function->{scope}") .
419 "\n";
420 $func .= " mov QWORD$PTR\[8+rsp\],rdi\t;WIN64 prologue\n";
421 $func .= " mov QWORD$PTR\[16+rsp\],rsi\n";
422 $func .= " mov rax,rsp\n";
423 $func .= "${decor}SEH_begin_$current_function->{name}:";
424 $func .= ":" if ($masm);
425 $func .= "\n";
426 my $narg = $current_function->{narg};
427 $narg=6 if (!defined($narg));
428 $func .= " mov rdi,rcx\n" if ($narg>0);
429 $func .= " mov rsi,rdx\n" if ($narg>1);
430 $func .= " mov rdx,r8\n" if ($narg>2);
431 $func .= " mov rcx,r9\n" if ($narg>3);
432 $func .= " mov r8,QWORD$PTR\[40+rsp\]\n" if ($narg>4);
433 $func .= " mov r9,QWORD$PTR\[48+rsp\]\n" if ($narg>5);
434 $func .= "\n";
435 } else {
436 "$current_function->{name}".
437 ($nasm ? ":" : "\tPROC $current_function->{scope}");
438 }
439 }
440 }
441 { package expr; # pick up expressions
442 sub re {
443 my ($class, $line, $opcode) = @_;
444 my $self = {};
445 my $ret;
446
447 if ($$line =~ /(^[^,]+)/) {
448 bless $self,$class;
449 $self->{value} = $1;
450 $ret = $self;
451 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
452
453 $self->{value} =~ s/\@PLT// if (!$elf);
454 $self->{value} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
455 $self->{value} =~ s/\.L/$decor/g;
456 $self->{opcode} = $opcode;
457 }
458 $ret;
459 }
460 sub out {
461 my $self = shift;
462 if ($nasm && $self->{opcode}->mnemonic()=~m/^j(?![re]cxz)/) {
463 "NEAR ".$self->{value};
464 } else {
465 $self->{value};
466 }
467 }
468 }
469 { package cfi_directive;
470 # CFI directives annotate instructions that are significant for
471 # stack unwinding procedure compliant with DWARF specification,
472 # see http://dwarfstd.org/. Besides naturally expected for this
473 # script platform-specific filtering function, this module adds
474 # three auxiliary synthetic directives not recognized by [GNU]
475 # assembler:
476 #
477 # - .cfi_push to annotate push instructions in prologue, which
478 # translates to .cfi_adjust_cfa_offset (if needed) and
479 # .cfi_offset;
480 # - .cfi_pop to annotate pop instructions in epilogue, which
481 # translates to .cfi_adjust_cfa_offset (if needed) and
482 # .cfi_restore;
483 # - [and most notably] .cfi_cfa_expression which encodes
484 # DW_CFA_def_cfa_expression and passes it to .cfi_escape as
485 # byte vector;
486 #
487 # CFA expressions were introduced in DWARF specification version
488 # 3 and describe how to deduce CFA, Canonical Frame Address. This
489 # becomes handy if your stack frame is variable and you can't
490 # spare register for [previous] frame pointer. Suggested directive
491 # syntax is made-up mix of DWARF operator suffixes [subset of]
492 # and references to registers with optional bias. Following example
493 # describes offloaded *original* stack pointer at specific offset
494 # from *current* stack pointer:
495 #
496 # .cfi_cfa_expression %rsp+40,deref,+8
497 #
498 # Final +8 has everything to do with the fact that CFA is defined
499 # as reference to top of caller's stack, and on x86_64 call to
500 # subroutine pushes 8-byte return address. In other words original
501 # stack pointer upon entry to a subroutine is 8 bytes off from CFA.
502
503 # Below constants are taken from "DWARF Expressions" section of the
504 # DWARF specification, section is numbered 7.7 in versions 3 and 4.
505 my %DW_OP_simple = ( # no-arg operators, mapped directly
506 deref => 0x06, dup => 0x12,
507 drop => 0x13, over => 0x14,
508 pick => 0x15, swap => 0x16,
509 rot => 0x17, xderef => 0x18,
510
511 abs => 0x19, and => 0x1a,
512 div => 0x1b, minus => 0x1c,
513 mod => 0x1d, mul => 0x1e,
514 neg => 0x1f, not => 0x20,
515 or => 0x21, plus => 0x22,
516 shl => 0x24, shr => 0x25,
517 shra => 0x26, xor => 0x27,
518 );
519
520 my %DW_OP_complex = ( # used in specific subroutines
521 constu => 0x10, # uleb128
522 consts => 0x11, # sleb128
523 plus_uconst => 0x23, # uleb128
524 lit0 => 0x30, # add 0-31 to opcode
525 reg0 => 0x50, # add 0-31 to opcode
526 breg0 => 0x70, # add 0-31 to opcole, sleb128
527 regx => 0x90, # uleb28
528 fbreg => 0x91, # sleb128
529 bregx => 0x92, # uleb128, sleb128
530 piece => 0x93, # uleb128
531 );
532
533 # Following constants are defined in x86_64 ABI supplement, for
534 # example available at https://www.uclibc.org/docs/psABI-x86_64.pdf,
535 # see section 3.7 "Stack Unwind Algorithm".
536 my %DW_reg_idx = (
537 "%rax"=>0, "%rdx"=>1, "%rcx"=>2, "%rbx"=>3,
538 "%rsi"=>4, "%rdi"=>5, "%rbp"=>6, "%rsp"=>7,
539 "%r8" =>8, "%r9" =>9, "%r10"=>10, "%r11"=>11,
540 "%r12"=>12, "%r13"=>13, "%r14"=>14, "%r15"=>15
541 );
542
543 my ($cfa_reg, $cfa_rsp);
544
545 # [us]leb128 format is variable-length integer representation base
546 # 2^128, with most significant bit of each byte being 0 denoting
547 # *last* most significant digit. See "Variable Length Data" in the
548 # DWARF specification, numbered 7.6 at least in versions 3 and 4.
549 sub sleb128 {
550 use integer; # get right shift extend sign
551
552 my $val = shift;
553 my $sign = ($val < 0) ? -1 : 0;
554 my @ret = ();
555
556 while(1) {
557 push @ret, $val&0x7f;
558
559 # see if remaining bits are same and equal to most
560 # significant bit of the current digit, if so, it's
561 # last digit...
562 last if (($val>>6) == $sign);
563
564 @ret[-1] |= 0x80;
565 $val >>= 7;
566 }
567
568 return @ret;
569 }
570 sub uleb128 {
571 my $val = shift;
572 my @ret = ();
573
574 while(1) {
575 push @ret, $val&0x7f;
576
577 # see if it's last significant digit...
578 last if (($val >>= 7) == 0);
579
580 @ret[-1] |= 0x80;
581 }
582
583 return @ret;
584 }
585 sub const {
586 my $val = shift;
587
588 if ($val >= 0 && $val < 32) {
589 return ($DW_OP_complex{lit0}+$val);
590 }
591 return ($DW_OP_complex{consts}, sleb128($val));
592 }
593 sub reg {
594 my $val = shift;
595
596 return if ($val !~ m/^(%r\w+)(?:([\+\-])((?:0x)?[0-9a-f]+))?/);
597
598 my $reg = $DW_reg_idx{$1};
599 my $off = eval ("0 $2 $3");
600
601 return (($DW_OP_complex{breg0} + $reg), sleb128($off));
602 # Yes, we use DW_OP_bregX+0 to push register value and not
603 # DW_OP_regX, because latter would require even DW_OP_piece,
604 # which would be a waste under the circumstances. If you have
605 # to use DWP_OP_reg, use "regx:N"...
606 }
607 sub cfa_expression {
608 my $line = shift;
609 my @ret;
610
611 foreach my $token (split(/,\s*/,$line)) {
612 if ($token =~ /^%r/) {
613 push @ret,reg($token);
614 } elsif ($token =~ /((?:0x)?[0-9a-f]+)\((%r\w+)\)/) {
615 push @ret,reg("$2+$1");
616 } elsif ($token =~ /(\w+):(\-?(?:0x)?[0-9a-f]+)(U?)/i) {
617 my $i = 1*eval($2);
618 push @ret,$DW_OP_complex{$1}, ($3 ? uleb128($i) : sleb128($i));
619 } elsif (my $i = 1*eval($token) or $token eq "0") {
620 if ($token =~ /^\+/) {
621 push @ret,$DW_OP_complex{plus_uconst},uleb128($i);
622 } else {
623 push @ret,const($i);
624 }
625 } else {
626 push @ret,$DW_OP_simple{$token};
627 }
628 }
629
630 # Finally we return DW_CFA_def_cfa_expression, 15, followed by
631 # length of the expression and of course the expression itself.
632 return (15,scalar(@ret),@ret);
633 }
634 sub re {
635 my ($class, $line) = @_;
636 my $self = {};
637 my $ret;
638
639 if ($$line =~ s/^\s*\.cfi_(\w+)\s*//) {
640 bless $self,$class;
641 $ret = $self;
642 undef $self->{value};
643 my $dir = $1;
644
645 SWITCH: for ($dir) {
646 # What is $cfa_rsp? Effectively it's difference between %rsp
647 # value and current CFA, Canonical Frame Address, which is
648 # why it starts with -8. Recall that CFA is top of caller's
649 # stack...
650 /startproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", -8); last; };
651 /endproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", 0); last; };
652 /def_cfa_register/
653 && do { $cfa_reg = $$line; last; };
654 /def_cfa_offset/
655 && do { $cfa_rsp = -1*eval($$line) if ($cfa_reg eq "%rsp");
656 last;
657 };
658 /adjust_cfa_offset/
659 && do { $cfa_rsp -= 1*eval($$line) if ($cfa_reg eq "%rsp");
660 last;
661 };
662 /def_cfa/ && do { if ($$line =~ /(%r\w+)\s*,\s*(.+)/) {
663 $cfa_reg = $1;
664 $cfa_rsp = -1*eval($2) if ($cfa_reg eq "%rsp");
665 }
666 last;
667 };
668 /push/ && do { $dir = undef;
669 $cfa_rsp -= 8;
670 if ($cfa_reg eq "%rsp") {
671 $self->{value} = ".cfi_adjust_cfa_offset\t8\n";
672 }
673 $self->{value} .= ".cfi_offset\t$$line,$cfa_rsp";
674 last;
675 };
676 /pop/ && do { $dir = undef;
677 $cfa_rsp += 8;
678 if ($cfa_reg eq "%rsp") {
679 $self->{value} = ".cfi_adjust_cfa_offset\t-8\n";
680 }
681 $self->{value} .= ".cfi_restore\t$$line";
682 last;
683 };
684 /cfa_expression/
685 && do { $dir = undef;
686 $self->{value} = ".cfi_escape\t" .
687 join(",", map(sprintf("0x%02x", $_),
688 cfa_expression($$line)));
689 last;
690 };
691 }
692
693 $self->{value} = ".cfi_$dir\t$$line" if ($dir);
694
695 $$line = "";
696 }
697
698 return $ret;
699 }
700 sub out {
701 my $self = shift;
702 return ($elf ? $self->{value} : undef);
703 }
704 }
705 { package directive; # pick up directives, which start with .
706 sub re {
707 my ($class, $line) = @_;
708 my $self = {};
709 my $ret;
710 my $dir;
711
712 # chain-call to cfi_directive
713 $ret = cfi_directive->re($line) and return $ret;
714
715 if ($$line =~ /^\s*(\.\w+)/) {
716 bless $self,$class;
717 $dir = $1;
718 $ret = $self;
719 undef $self->{value};
720 $$line = substr($$line,@+[0]); $$line =~ s/^\s+//;
721
722 SWITCH: for ($dir) {
723 /\.global|\.globl|\.extern/
724 && do { $globals{$$line} = $prefix . $$line;
725 $$line = $globals{$$line} if ($prefix);
726 last;
727 };
728 /\.type/ && do { my ($sym,$type,$narg) = split(',',$$line);
729 if ($type eq "\@function") {
730 undef $current_function;
731 $current_function->{name} = $sym;
732 $current_function->{abi} = "svr4";
733 $current_function->{narg} = $narg;
734 $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE";
735 } elsif ($type eq "\@abi-omnipotent") {
736 undef $current_function;
737 $current_function->{name} = $sym;
738 $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE";
739 }
740 $$line =~ s/\@abi\-omnipotent/\@function/;
741 $$line =~ s/\@function.*/\@function/;
742 last;
743 };
744 /\.asciz/ && do { if ($$line =~ /^"(.*)"$/) {
745 $dir = ".byte";
746 $$line = join(",",unpack("C*",$1),0);
747 }
748 last;
749 };
750 /\.rva|\.long|\.quad/
751 && do { $$line =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei;
752 $$line =~ s/\.L/$decor/g;
753 last;
754 };
755 }
756
757 if ($gas) {
758 $self->{value} = $dir . "\t" . $$line;
759
760 if ($dir =~ /\.extern/) {
761 $self->{value} = ""; # swallow extern
762 } elsif (!$elf && $dir =~ /\.type/) {
763 $self->{value} = "";
764 $self->{value} = ".def\t" . ($globals{$1} or $1) . ";\t" .
765 (defined($globals{$1})?".scl 2;":".scl 3;") .
766 "\t.type 32;\t.endef"
767 if ($win64 && $$line =~ /([^,]+),\@function/);
768 } elsif (!$elf && $dir =~ /\.size/) {
769 $self->{value} = "";
770 if (defined($current_function)) {
771 $self->{value} .= "${decor}SEH_end_$current_function->{name}:"
772 if ($win64 && $current_function->{abi} eq "svr4");
773 undef $current_function;
774 }
775 } elsif (!$elf && $dir =~ /\.align/) {
776 $self->{value} = ".p2align\t" . (log($$line)/log(2));
777 } elsif ($dir eq ".section") {
778 $current_segment=$$line;
779 if (!$elf && $current_segment eq ".init") {
780 if ($flavour eq "macosx") { $self->{value} = ".mod_init_func"; }
781 elsif ($flavour eq "mingw64") { $self->{value} = ".section\t.ctors"; }
782 }
783 } elsif ($dir =~ /\.(text|data)/) {
784 $current_segment=".$1";
785 } elsif ($dir =~ /\.hidden/) {
786 if ($flavour eq "macosx") { $self->{value} = ".private_extern\t$prefix$$line"; }
787 elsif ($flavour eq "mingw64") { $self->{value} = ""; }
788 } elsif ($dir =~ /\.comm/) {
789 $self->{value} = "$dir\t$prefix$$line";
790 $self->{value} =~ s|,([0-9]+),([0-9]+)$|",$1,".log($2)/log(2)|e if ($flavour eq "macosx");
791 }
792 $$line = "";
793 return $self;
794 }
795
796 # non-gas case or nasm/masm
797 SWITCH: for ($dir) {
798 /\.text/ && do { my $v=undef;
799 if ($nasm) {
800 $v="section .text code align=64\n";
801 } else {
802 $v="$current_segment\tENDS\n" if ($current_segment);
803 $current_segment = ".text\$";
804 $v.="$current_segment\tSEGMENT ";
805 $v.=$masm>=$masmref ? "ALIGN(256)" : "PAGE";
806 $v.=" 'CODE'";
807 }
808 $self->{value} = $v;
809 last;
810 };
811 /\.data/ && do { my $v=undef;
812 if ($nasm) {
813 $v="section .data data align=8\n";
814 } else {
815 $v="$current_segment\tENDS\n" if ($current_segment);
816 $current_segment = "_DATA";
817 $v.="$current_segment\tSEGMENT";
818 }
819 $self->{value} = $v;
820 last;
821 };
822 /\.section/ && do { my $v=undef;
823 $$line =~ s/([^,]*).*/$1/;
824 $$line = ".CRT\$XCU" if ($$line eq ".init");
825 if ($nasm) {
826 $v="section $$line";
827 if ($$line=~/\.([px])data/) {
828 $v.=" rdata align=";
829 $v.=$1 eq "p"? 4 : 8;
830 } elsif ($$line=~/\.CRT\$/i) {
831 $v.=" rdata align=8";
832 }
833 } else {
834 $v="$current_segment\tENDS\n" if ($current_segment);
835 $v.="$$line\tSEGMENT";
836 if ($$line=~/\.([px])data/) {
837 $v.=" READONLY";
838 $v.=" ALIGN(".($1 eq "p" ? 4 : 8).")" if ($masm>=$masmref);
839 } elsif ($$line=~/\.CRT\$/i) {
840 $v.=" READONLY ";
841 $v.=$masm>=$masmref ? "ALIGN(8)" : "DWORD";
842 }
843 }
844 $current_segment = $$line;
845 $self->{value} = $v;
846 last;
847 };
848 /\.extern/ && do { $self->{value} = "EXTERN\t".$$line;
849 $self->{value} .= ":NEAR" if ($masm);
850 last;
851 };
852 /\.globl|.global/
853 && do { $self->{value} = $masm?"PUBLIC":"global";
854 $self->{value} .= "\t".$$line;
855 last;
856 };
857 /\.size/ && do { if (defined($current_function)) {
858 undef $self->{value};
859 if ($current_function->{abi} eq "svr4") {
860 $self->{value}="${decor}SEH_end_$current_function->{name}:";
861 $self->{value}.=":\n" if($masm);
862 }
863 $self->{value}.="$current_function->{name}\tENDP" if($masm && $current_function->{name});
864 undef $current_function;
865 }
866 last;
867 };
868 /\.align/ && do { my $max = ($masm && $masm>=$masmref) ? 256 : 4096;
869 $self->{value} = "ALIGN\t".($$line>$max?$max:$$line);
870 last;
871 };
872 /\.(value|long|rva|quad)/
873 && do { my $sz = substr($1,0,1);
874 my @arr = split(/,\s*/,$$line);
875 my $last = pop(@arr);
876 my $conv = sub { my $var=shift;
877 $var=~s/^(0b[0-1]+)/oct($1)/eig;
878 $var=~s/^0x([0-9a-f]+)/0$1h/ig if ($masm);
879 if ($sz eq "D" && ($current_segment=~/.[px]data/ || $dir eq ".rva"))
880 { $var=~s/([_a-z\$\@][_a-z0-9\$\@]*)/$nasm?"$1 wrt ..imagebase":"imagerel $1"/egi; }
881 $var;
882 };
883
884 $sz =~ tr/bvlrq/BWDDQ/;
885 $self->{value} = "\tD$sz\t";
886 for (@arr) { $self->{value} .= &$conv($_).","; }
887 $self->{value} .= &$conv($last);
888 last;
889 };
890 /\.byte/ && do { my @str=split(/,\s*/,$$line);
891 map(s/(0b[0-1]+)/oct($1)/eig,@str);
892 map(s/0x([0-9a-f]+)/0$1h/ig,@str) if ($masm);
893 while ($#str>15) {
894 $self->{value}.="DB\t"
895 .join(",",@str[0..15])."\n";
896 foreach (0..15) { shift @str; }
897 }
898 $self->{value}.="DB\t"
899 .join(",",@str) if (@str);
900 last;
901 };
902 /\.comm/ && do { my @str=split(/,\s*/,$$line);
903 my $v=undef;
904 if ($nasm) {
905 $v.="common $prefix@str[0] @str[1]";
906 } else {
907 $v="$current_segment\tENDS\n" if ($current_segment);
908 $current_segment = "_DATA";
909 $v.="$current_segment\tSEGMENT\n";
910 $v.="COMM @str[0]:DWORD:".@str[1]/4;
911 }
912 $self->{value} = $v;
913 last;
914 };
915 }
916 $$line = "";
917 }
918
919 $ret;
920 }
921 sub out {
922 my $self = shift;
923 $self->{value};
924 }
925 }
926
927 # Upon initial x86_64 introduction SSE>2 extensions were not introduced
928 # yet. In order not to be bothered by tracing exact assembler versions,
929 # but at the same time to provide a bare security minimum of AES-NI, we
930 # hard-code some instructions. Extensions past AES-NI on the other hand
931 # are traced by examining assembler version in individual perlasm
932 # modules...
933
934 my %regrm = ( "%eax"=>0, "%ecx"=>1, "%edx"=>2, "%ebx"=>3,
935 "%esp"=>4, "%ebp"=>5, "%esi"=>6, "%edi"=>7 );
936
937 sub rex {
938 my $opcode=shift;
939 my ($dst,$src,$rex)=@_;
940
941 $rex|=0x04 if($dst>=8);
942 $rex|=0x01 if($src>=8);
943 push @$opcode,($rex|0x40) if ($rex);
944 }
945
946 my $movq = sub { # elderly gas can't handle inter-register movq
947 my $arg = shift;
948 my @opcode=(0x66);
949 if ($arg =~ /%xmm([0-9]+),\s*%r(\w+)/) {
950 my ($src,$dst)=($1,$2);
951 if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; }
952 rex(\@opcode,$src,$dst,0x8);
953 push @opcode,0x0f,0x7e;
954 push @opcode,0xc0|(($src&7)<<3)|($dst&7); # ModR/M
955 @opcode;
956 } elsif ($arg =~ /%r(\w+),\s*%xmm([0-9]+)/) {
957 my ($src,$dst)=($2,$1);
958 if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; }
959 rex(\@opcode,$src,$dst,0x8);
960 push @opcode,0x0f,0x6e;
961 push @opcode,0xc0|(($src&7)<<3)|($dst&7); # ModR/M
962 @opcode;
963 } else {
964 ();
965 }
966 };
967
968 my $pextrd = sub {
969 if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*(%\w+)/) {
970 my @opcode=(0x66);
971 my $imm=$1;
972 my $src=$2;
973 my $dst=$3;
974 if ($dst =~ /%r([0-9]+)d/) { $dst = $1; }
975 elsif ($dst =~ /%e/) { $dst = $regrm{$dst}; }
976 rex(\@opcode,$src,$dst);
977 push @opcode,0x0f,0x3a,0x16;
978 push @opcode,0xc0|(($src&7)<<3)|($dst&7); # ModR/M
979 push @opcode,$imm;
980 @opcode;
981 } else {
982 ();
983 }
984 };
985
986 my $pinsrd = sub {
987 if (shift =~ /\$([0-9]+),\s*(%\w+),\s*%xmm([0-9]+)/) {
988 my @opcode=(0x66);
989 my $imm=$1;
990 my $src=$2;
991 my $dst=$3;
992 if ($src =~ /%r([0-9]+)/) { $src = $1; }
993 elsif ($src =~ /%e/) { $src = $regrm{$src}; }
994 rex(\@opcode,$dst,$src);
995 push @opcode,0x0f,0x3a,0x22;
996 push @opcode,0xc0|(($dst&7)<<3)|($src&7); # ModR/M
997 push @opcode,$imm;
998 @opcode;
999 } else {
1000 ();
1001 }
1002 };
1003
1004 my $pshufb = sub {
1005 if (shift =~ /%xmm([0-9]+),\s*%xmm([0-9]+)/) {
1006 my @opcode=(0x66);
1007 rex(\@opcode,$2,$1);
1008 push @opcode,0x0f,0x38,0x00;
1009 push @opcode,0xc0|($1&7)|(($2&7)<<3); # ModR/M
1010 @opcode;
1011 } else {
1012 ();
1013 }
1014 };
1015
1016 my $palignr = sub {
1017 if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
1018 my @opcode=(0x66);
1019 rex(\@opcode,$3,$2);
1020 push @opcode,0x0f,0x3a,0x0f;
1021 push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M
1022 push @opcode,$1;
1023 @opcode;
1024 } else {
1025 ();
1026 }
1027 };
1028
1029 my $pclmulqdq = sub {
1030 if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
1031 my @opcode=(0x66);
1032 rex(\@opcode,$3,$2);
1033 push @opcode,0x0f,0x3a,0x44;
1034 push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M
1035 my $c=$1;
1036 push @opcode,$c=~/^0/?oct($c):$c;
1037 @opcode;
1038 } else {
1039 ();
1040 }
1041 };
1042
1043 my $rdrand = sub {
1044 if (shift =~ /%[er](\w+)/) {
1045 my @opcode=();
1046 my $dst=$1;
1047 if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; }
1048 rex(\@opcode,0,$dst,8);
1049 push @opcode,0x0f,0xc7,0xf0|($dst&7);
1050 @opcode;
1051 } else {
1052 ();
1053 }
1054 };
1055
1056 my $rdseed = sub {
1057 if (shift =~ /%[er](\w+)/) {
1058 my @opcode=();
1059 my $dst=$1;
1060 if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; }
1061 rex(\@opcode,0,$dst,8);
1062 push @opcode,0x0f,0xc7,0xf8|($dst&7);
1063 @opcode;
1064 } else {
1065 ();
1066 }
1067 };
1068
1069 # Not all AVX-capable assemblers recognize AMD XOP extension. Since we
1070 # are using only two instructions hand-code them in order to be excused
1071 # from chasing assembler versions...
1072
1073 sub rxb {
1074 my $opcode=shift;
1075 my ($dst,$src1,$src2,$rxb)=@_;
1076
1077 $rxb|=0x7<<5;
1078 $rxb&=~(0x04<<5) if($dst>=8);
1079 $rxb&=~(0x01<<5) if($src1>=8);
1080 $rxb&=~(0x02<<5) if($src2>=8);
1081 push @$opcode,$rxb;
1082 }
1083
1084 my $vprotd = sub {
1085 if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
1086 my @opcode=(0x8f);
1087 rxb(\@opcode,$3,$2,-1,0x08);
1088 push @opcode,0x78,0xc2;
1089 push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M
1090 my $c=$1;
1091 push @opcode,$c=~/^0/?oct($c):$c;
1092 @opcode;
1093 } else {
1094 ();
1095 }
1096 };
1097
1098 my $vprotq = sub {
1099 if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) {
1100 my @opcode=(0x8f);
1101 rxb(\@opcode,$3,$2,-1,0x08);
1102 push @opcode,0x78,0xc3;
1103 push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M
1104 my $c=$1;
1105 push @opcode,$c=~/^0/?oct($c):$c;
1106 @opcode;
1107 } else {
1108 ();
1109 }
1110 };
1111
1112 # Intel Control-flow Enforcement Technology extension. All functions and
1113 # indirect branch targets will have to start with this instruction...
1114
1115 my $endbranch = sub {
1116 (0xf3,0x0f,0x1e,0xfa);
1117 };
1118
1119 ########################################################################
1120
1121 if ($nasm) {
1122 print <<___;
1123 default rel
1124 %define XMMWORD
1125 %define YMMWORD
1126 %define ZMMWORD
1127 ___
1128 } elsif ($masm) {
1129 print <<___;
1130 OPTION DOTNAME
1131 ___
1132 }
1133 while(defined(my $line=<>)) {
1134
1135 $line =~ s|\R$||; # Better chomp
1136
1137 $line =~ s|[#!].*$||; # get rid of asm-style comments...
1138 $line =~ s|/\*.*\*/||; # ... and C-style comments...
1139 $line =~ s|^\s+||; # ... and skip white spaces in beginning
1140 $line =~ s|\s+$||; # ... and at the end
1141
1142 if (my $label=label->re(\$line)) { print $label->out(); }
1143
1144 if (my $directive=directive->re(\$line)) {
1145 printf "%s",$directive->out();
1146 } elsif (my $opcode=opcode->re(\$line)) {
1147 my $asm = eval("\$".$opcode->mnemonic());
1148
1149 if ((ref($asm) eq 'CODE') && scalar(my @bytes=&$asm($line))) {
1150 print $gas?".byte\t":"DB\t",join(',',@bytes),"\n";
1151 next;
1152 }
1153
1154 my @args;
1155 ARGUMENT: while (1) {
1156 my $arg;
1157
1158 ($arg=register->re(\$line, $opcode))||
1159 ($arg=const->re(\$line)) ||
1160 ($arg=ea->re(\$line, $opcode)) ||
1161 ($arg=expr->re(\$line, $opcode)) ||
1162 last ARGUMENT;
1163
1164 push @args,$arg;
1165
1166 last ARGUMENT if ($line !~ /^,/);
1167
1168 $line =~ s/^,\s*//;
1169 } # ARGUMENT:
1170
1171 if ($#args>=0) {
1172 my $insn;
1173 my $sz=$opcode->size();
1174
1175 if ($gas) {
1176 $insn = $opcode->out($#args>=1?$args[$#args]->size():$sz);
1177 @args = map($_->out($sz),@args);
1178 printf "\t%s\t%s",$insn,join(",",@args);
1179 } else {
1180 $insn = $opcode->out();
1181 foreach (@args) {
1182 my $arg = $_->out();
1183 # $insn.=$sz compensates for movq, pinsrw, ...
1184 if ($arg =~ /^xmm[0-9]+$/) { $insn.=$sz; $sz="x" if(!$sz); last; }
1185 if ($arg =~ /^ymm[0-9]+$/) { $insn.=$sz; $sz="y" if(!$sz); last; }
1186 if ($arg =~ /^zmm[0-9]+$/) { $insn.=$sz; $sz="z" if(!$sz); last; }
1187 if ($arg =~ /^mm[0-9]+$/) { $insn.=$sz; $sz="q" if(!$sz); last; }
1188 }
1189 @args = reverse(@args);
1190 undef $sz if ($nasm && $opcode->mnemonic() eq "lea");
1191 printf "\t%s\t%s",$insn,join(",",map($_->out($sz),@args));
1192 }
1193 } else {
1194 printf "\t%s",$opcode->out();
1195 }
1196 }
1197
1198 print $line,"\n";
1199 }
1200
1201 print "\n$current_segment\tENDS\n" if ($current_segment && $masm);
1202 print "END\n" if ($masm);
1203
1204 close STDOUT;
1205
1206 \f#################################################
1207 # Cross-reference x86_64 ABI "card"
1208 #
1209 # Unix Win64
1210 # %rax * *
1211 # %rbx - -
1212 # %rcx #4 #1
1213 # %rdx #3 #2
1214 # %rsi #2 -
1215 # %rdi #1 -
1216 # %rbp - -
1217 # %rsp - -
1218 # %r8 #5 #3
1219 # %r9 #6 #4
1220 # %r10 * *
1221 # %r11 * *
1222 # %r12 - -
1223 # %r13 - -
1224 # %r14 - -
1225 # %r15 - -
1226 #
1227 # (*) volatile register
1228 # (-) preserved by callee
1229 # (#) Nth argument, volatile
1230 #
1231 # In Unix terms top of stack is argument transfer area for arguments
1232 # which could not be accommodated in registers. Or in other words 7th
1233 # [integer] argument resides at 8(%rsp) upon function entry point.
1234 # 128 bytes above %rsp constitute a "red zone" which is not touched
1235 # by signal handlers and can be used as temporal storage without
1236 # allocating a frame.
1237 #
1238 # In Win64 terms N*8 bytes on top of stack is argument transfer area,
1239 # which belongs to/can be overwritten by callee. N is the number of
1240 # arguments passed to callee, *but* not less than 4! This means that
1241 # upon function entry point 5th argument resides at 40(%rsp), as well
1242 # as that 32 bytes from 8(%rsp) can always be used as temporal
1243 # storage [without allocating a frame]. One can actually argue that
1244 # one can assume a "red zone" above stack pointer under Win64 as well.
1245 # Point is that at apparently no occasion Windows kernel would alter
1246 # the area above user stack pointer in true asynchronous manner...
1247 #
1248 # All the above means that if assembler programmer adheres to Unix
1249 # register and stack layout, but disregards the "red zone" existence,
1250 # it's possible to use following prologue and epilogue to "gear" from
1251 # Unix to Win64 ABI in leaf functions with not more than 6 arguments.
1252 #
1253 # omnipotent_function:
1254 # ifdef WIN64
1255 # movq %rdi,8(%rsp)
1256 # movq %rsi,16(%rsp)
1257 # movq %rcx,%rdi ; if 1st argument is actually present
1258 # movq %rdx,%rsi ; if 2nd argument is actually ...
1259 # movq %r8,%rdx ; if 3rd argument is ...
1260 # movq %r9,%rcx ; if 4th argument ...
1261 # movq 40(%rsp),%r8 ; if 5th ...
1262 # movq 48(%rsp),%r9 ; if 6th ...
1263 # endif
1264 # ...
1265 # ifdef WIN64
1266 # movq 8(%rsp),%rdi
1267 # movq 16(%rsp),%rsi
1268 # endif
1269 # ret
1270 #
1271 \f#################################################
1272 # Win64 SEH, Structured Exception Handling.
1273 #
1274 # Unlike on Unix systems(*) lack of Win64 stack unwinding information
1275 # has undesired side-effect at run-time: if an exception is raised in
1276 # assembler subroutine such as those in question (basically we're
1277 # referring to segmentation violations caused by malformed input
1278 # parameters), the application is briskly terminated without invoking
1279 # any exception handlers, most notably without generating memory dump
1280 # or any user notification whatsoever. This poses a problem. It's
1281 # possible to address it by registering custom language-specific
1282 # handler that would restore processor context to the state at
1283 # subroutine entry point and return "exception is not handled, keep
1284 # unwinding" code. Writing such handler can be a challenge... But it's
1285 # doable, though requires certain coding convention. Consider following
1286 # snippet:
1287 #
1288 # .type function,@function
1289 # function:
1290 # movq %rsp,%rax # copy rsp to volatile register
1291 # pushq %r15 # save non-volatile registers
1292 # pushq %rbx
1293 # pushq %rbp
1294 # movq %rsp,%r11
1295 # subq %rdi,%r11 # prepare [variable] stack frame
1296 # andq $-64,%r11
1297 # movq %rax,0(%r11) # check for exceptions
1298 # movq %r11,%rsp # allocate [variable] stack frame
1299 # movq %rax,0(%rsp) # save original rsp value
1300 # magic_point:
1301 # ...
1302 # movq 0(%rsp),%rcx # pull original rsp value
1303 # movq -24(%rcx),%rbp # restore non-volatile registers
1304 # movq -16(%rcx),%rbx
1305 # movq -8(%rcx),%r15
1306 # movq %rcx,%rsp # restore original rsp
1307 # magic_epilogue:
1308 # ret
1309 # .size function,.-function
1310 #
1311 # The key is that up to magic_point copy of original rsp value remains
1312 # in chosen volatile register and no non-volatile register, except for
1313 # rsp, is modified. While past magic_point rsp remains constant till
1314 # the very end of the function. In this case custom language-specific
1315 # exception handler would look like this:
1316 #
1317 # EXCEPTION_DISPOSITION handler (EXCEPTION_RECORD *rec,ULONG64 frame,
1318 # CONTEXT *context,DISPATCHER_CONTEXT *disp)
1319 # { ULONG64 *rsp = (ULONG64 *)context->Rax;
1320 # ULONG64 rip = context->Rip;
1321 #
1322 # if (rip >= magic_point)
1323 # { rsp = (ULONG64 *)context->Rsp;
1324 # if (rip < magic_epilogue)
1325 # { rsp = (ULONG64 *)rsp[0];
1326 # context->Rbp = rsp[-3];
1327 # context->Rbx = rsp[-2];
1328 # context->R15 = rsp[-1];
1329 # }
1330 # }
1331 # context->Rsp = (ULONG64)rsp;
1332 # context->Rdi = rsp[1];
1333 # context->Rsi = rsp[2];
1334 #
1335 # memcpy (disp->ContextRecord,context,sizeof(CONTEXT));
1336 # RtlVirtualUnwind(UNW_FLAG_NHANDLER,disp->ImageBase,
1337 # dips->ControlPc,disp->FunctionEntry,disp->ContextRecord,
1338 # &disp->HandlerData,&disp->EstablisherFrame,NULL);
1339 # return ExceptionContinueSearch;
1340 # }
1341 #
1342 # It's appropriate to implement this handler in assembler, directly in
1343 # function's module. In order to do that one has to know members'
1344 # offsets in CONTEXT and DISPATCHER_CONTEXT structures and some constant
1345 # values. Here they are:
1346 #
1347 # CONTEXT.Rax 120
1348 # CONTEXT.Rcx 128
1349 # CONTEXT.Rdx 136
1350 # CONTEXT.Rbx 144
1351 # CONTEXT.Rsp 152
1352 # CONTEXT.Rbp 160
1353 # CONTEXT.Rsi 168
1354 # CONTEXT.Rdi 176
1355 # CONTEXT.R8 184
1356 # CONTEXT.R9 192
1357 # CONTEXT.R10 200
1358 # CONTEXT.R11 208
1359 # CONTEXT.R12 216
1360 # CONTEXT.R13 224
1361 # CONTEXT.R14 232
1362 # CONTEXT.R15 240
1363 # CONTEXT.Rip 248
1364 # CONTEXT.Xmm6 512
1365 # sizeof(CONTEXT) 1232
1366 # DISPATCHER_CONTEXT.ControlPc 0
1367 # DISPATCHER_CONTEXT.ImageBase 8
1368 # DISPATCHER_CONTEXT.FunctionEntry 16
1369 # DISPATCHER_CONTEXT.EstablisherFrame 24
1370 # DISPATCHER_CONTEXT.TargetIp 32
1371 # DISPATCHER_CONTEXT.ContextRecord 40
1372 # DISPATCHER_CONTEXT.LanguageHandler 48
1373 # DISPATCHER_CONTEXT.HandlerData 56
1374 # UNW_FLAG_NHANDLER 0
1375 # ExceptionContinueSearch 1
1376 #
1377 # In order to tie the handler to the function one has to compose
1378 # couple of structures: one for .xdata segment and one for .pdata.
1379 #
1380 # UNWIND_INFO structure for .xdata segment would be
1381 #
1382 # function_unwind_info:
1383 # .byte 9,0,0,0
1384 # .rva handler
1385 #
1386 # This structure designates exception handler for a function with
1387 # zero-length prologue, no stack frame or frame register.
1388 #
1389 # To facilitate composing of .pdata structures, auto-generated "gear"
1390 # prologue copies rsp value to rax and denotes next instruction with
1391 # .LSEH_begin_{function_name} label. This essentially defines the SEH
1392 # styling rule mentioned in the beginning. Position of this label is
1393 # chosen in such manner that possible exceptions raised in the "gear"
1394 # prologue would be accounted to caller and unwound from latter's frame.
1395 # End of function is marked with respective .LSEH_end_{function_name}
1396 # label. To summarize, .pdata segment would contain
1397 #
1398 # .rva .LSEH_begin_function
1399 # .rva .LSEH_end_function
1400 # .rva function_unwind_info
1401 #
1402 # Reference to function_unwind_info from .xdata segment is the anchor.
1403 # In case you wonder why references are 32-bit .rvas and not 64-bit
1404 # .quads. References put into these two segments are required to be
1405 # *relative* to the base address of the current binary module, a.k.a.
1406 # image base. No Win64 module, be it .exe or .dll, can be larger than
1407 # 2GB and thus such relative references can be and are accommodated in
1408 # 32 bits.
1409 #
1410 # Having reviewed the example function code, one can argue that "movq
1411 # %rsp,%rax" above is redundant. It is not! Keep in mind that on Unix
1412 # rax would contain an undefined value. If this "offends" you, use
1413 # another register and refrain from modifying rax till magic_point is
1414 # reached, i.e. as if it was a non-volatile register. If more registers
1415 # are required prior [variable] frame setup is completed, note that
1416 # nobody says that you can have only one "magic point." You can
1417 # "liberate" non-volatile registers by denoting last stack off-load
1418 # instruction and reflecting it in finer grade unwind logic in handler.
1419 # After all, isn't it why it's called *language-specific* handler...
1420 #
1421 # SE handlers are also involved in unwinding stack when executable is
1422 # profiled or debugged. Profiling implies additional limitations that
1423 # are too subtle to discuss here. For now it's sufficient to say that
1424 # in order to simplify handlers one should either a) offload original
1425 # %rsp to stack (like discussed above); or b) if you have a register to
1426 # spare for frame pointer, choose volatile one.
1427 #
1428 # (*) Note that we're talking about run-time, not debug-time. Lack of
1429 # unwind information makes debugging hard on both Windows and
1430 # Unix. "Unlike" refers to the fact that on Unix signal handler
1431 # will always be invoked, core dumped and appropriate exit code
1432 # returned to parent (for user notification).
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