projects / thirdparty / openssl.git / blame
| Commit | Line | Data |
|---|---|---|
| 1cfd258e AP |
1 | #!/usr/bin/env perl |
| 2 | ||
| 80aa9cc9 | 3 | # Ascetic x86_64 AT&T to MASM/NASM assembler translator by <appro>. |
| 1cfd258e AP |
4 | # |
| 5 | # Why AT&T to MASM and not vice versa? Several reasons. Because AT&T | |
| 6 | # format is way easier to parse. Because it's simpler to "gear" from | |
| 7 | # Unix ABI to Windows one [see cross-reference "card" at the end of | |
| 8 | # file]. Because Linux targets were available first... | |
| 9 | # | |
| 10 | # In addition the script also "distills" code suitable for GNU | |
| 11 | # assembler, so that it can be compiled with more rigid assemblers, | |
| 12 | # such as Solaris /usr/ccs/bin/as. | |
| 13 | # | |
| 14 | # This translator is not designed to convert *arbitrary* assembler | |
| 15 | # code from AT&T format to MASM one. It's designed to convert just | |
| 16 | # enough to provide for dual-ABI OpenSSL modules development... | |
| 17 | # There *are* limitations and you might have to modify your assembler | |
| 18 | # code or this script to achieve the desired result... | |
| 19 | # | |
| 20 | # Currently recognized limitations: | |
| 21 | # | |
| 22 | # - can't use multiple ops per line; | |
| 1cfd258e AP |
23 | # |
| 24 | # Dual-ABI styling rules. | |
| 25 | # | |
| 80aa9cc9 AP |
26 | # 1. Adhere to Unix register and stack layout [see cross-reference |
| 27 | # ABI "card" at the end for explanation]. | |
| 1cfd258e AP |
28 | # 2. Forget about "red zone," stick to more traditional blended |
| 29 | # stack frame allocation. If volatile storage is actually required | |
| 30 | # that is. If not, just leave the stack as is. | |
| 31 | # 3. Functions tagged with ".type name,@function" get crafted with | |
| 4b450519 | 32 | # unified Win64 prologue and epilogue automatically. If you want |
| 1cfd258e | 33 | # to take care of ABI differences yourself, tag functions as |
| 4b450519 AP |
34 | # ".type name,@abi-omnipotent" instead. |
| 35 | # 4. To optimize the Win64 prologue you can specify number of input | |
| 36 | # arguments as ".type name,@function,N." Keep in mind that if N is | |
| 37 | # larger than 6, then you *have to* write "abi-omnipotent" code, | |
| 38 | # because >6 cases can't be addressed with unified prologue. | |
| 39 | # 5. Name local labels as .L*, do *not* use dynamic labels such as 1: | |
| 40 | # (sorry about latter). | |
| 41 | # 6. Don't use [or hand-code with .byte] "rep ret." "ret" mnemonic is | |
| 42 | # required to identify the spots, where to inject Win64 epilogue! | |
| 43 | # But on the pros, it's then prefixed with rep automatically:-) | |
| 85253772 AP |
44 | # 7. Stick to explicit ip-relative addressing. If you have to use |
| 45 | # GOTPCREL addressing, stick to mov symbol@GOTPCREL(%rip),%r??. | |
| 46 | # Both are recognized and translated to proper Win64 addressing | |
| 47 | # modes. To support legacy code a synthetic directive, .picmeup, | |
| 48 | # is implemented. It puts address of the *next* instruction into | |
| 49 | # target register, e.g.: | |
| 5d0d60e2 | 50 | # |
| 5d0d60e2 AP |
51 | # .picmeup %rax |
| 52 | # lea .Label-.(%rax),%rax | |
| 80aa9cc9 AP |
53 | # |
| 54 | # 8. In order to provide for structured exception handling unified | |
| 55 | # Win64 prologue copies %rsp value to %rax. For further details | |
| 56 | # see SEH paragraph at the end. | |
| 85253772 | 57 | # 9. .init segment is allowed to contain calls to functions only. |
| 80aa9cc9 | 58 | \f |
| 85253772 AP |
59 | my $flavour = shift; |
| 60 | my $output = shift; | |
| 61 | if ($flavour =~ /\./) { $output = $flavour; undef $flavour; } | |
| 932cc129 AP |
62 | |
| 63 | { my ($stddev,$stdino,@junk)=stat(STDOUT); | |
| 64 | my ($outdev,$outino,@junk)=stat($output); | |
| 65 | ||
| 66 | open STDOUT,">$output" || die "can't open $output: $!" | |
| 67 | if ($stddev!=$outdev || $stdino!=$outino); | |
| 68 | } | |
| 1cfd258e | 69 | |
| 85253772 AP |
70 | my $gas=1; $gas=0 if ($output =~ /\.asm$/); |
| 71 | my $elf=1; $elf=0 if (!$gas); | |
| 72 | my $win64=0; | |
| 73 | my $prefix=""; | |
| a23e3dbe | 74 | |
| 8ab9025e | 75 | my $masmref=8 + 50727*2**-32; # 8.00.50727 shipped with VS2005 |
| 9b634c9b | 76 | my $masm=0; |
| a23e3dbe AP |
77 | my $PTR=" PTR"; |
| 78 | ||
| 9b634c9b | 79 | my $nasmref=2.03; |
| a23e3dbe AP |
80 | my $nasm=0; |
| 81 | ||
| 85253772 AP |
82 | if ($flavour eq "mingw64") { $gas=1; $elf=0; $win64=1; $prefix="_"; } |
| 83 | elsif ($flavour eq "macosx") { $gas=1; $elf=0; $prefix="_"; } | |
| 84 | elsif ($flavour eq "masm") { $gas=0; $elf=0; $masm=$masmref; $win64=1; } | |
| 85 | elsif ($flavour eq "nasm") { $gas=0; $elf=0; $nasm=$nasmref; $win64=1; $PTR=""; } | |
| 86 | elsif (!$gas) | |
| 9b634c9b AP |
87 | { if ($ENV{ASM} =~ m/nasm/ && `nasm -v` =~ m/version ([0-9]+)\.([0-9]+)/i) |
| 88 | { $nasm = $1 + $2*0.01; $PTR=""; } | |
| a23e3dbe AP |
89 | elsif (`ml64 2>&1` =~ m/Version ([0-9]+)\.([0-9]+)(\.([0-9]+))?/) |
| 90 | { $masm = $1 + $2*2**-16 + $4*2**-32; } | |
| 9b634c9b | 91 | die "no assembler found on %PATH" if (!($nasm || $masm)); |
| 85253772 AP |
92 | $win64=1; |
| 93 | $elf=0; | |
| a23e3dbe | 94 | } |
| 1cfd258e AP |
95 | |
| 96 | my $current_segment; | |
| 97 | my $current_function; | |
| 9b634c9b | 98 | my %globals; |
| 1cfd258e AP |
99 | |
| 100 | { package opcode; # pick up opcodes | |
| 101 | sub re { | |
| 102 | my $self = shift; # single instance in enough... | |
| 103 | local *line = shift; | |
| 104 | undef $ret; | |
| 105 | ||
| 932cc129 | 106 | if ($line =~ /^([a-z][a-z0-9]*)/i) { |
| 1cfd258e AP |
107 | $self->{op} = $1; |
| 108 | $ret = $self; | |
| 109 | $line = substr($line,@+[0]); $line =~ s/^\s+//; | |
| 110 | ||
| 111 | undef $self->{sz}; | |
| a078befc | 112 | if ($self->{op} =~ /^(movz)b.*/) { # movz is pain... |
| 1cfd258e AP |
113 | $self->{op} = $1; |
| 114 | $self->{sz} = "b"; | |
| 9b634c9b | 115 | } elsif ($self->{op} =~ /call|jmp/) { |
| 55eab3b7 | 116 | $self->{sz} = "" |
| a078befc | 117 | } elsif ($self->{op} =~ /([a-z]{3,})([qlwb])$/) { |
| 1cfd258e AP |
118 | $self->{op} = $1; |
| 119 | $self->{sz} = $2; | |
| 120 | } | |
| 121 | } | |
| 122 | $ret; | |
| 123 | } | |
| 124 | sub size { | |
| 125 | my $self = shift; | |
| 126 | my $sz = shift; | |
| 127 | $self->{sz} = $sz if (defined($sz) && !defined($self->{sz})); | |
| 128 | $self->{sz}; | |
| 129 | } | |
| 130 | sub out { | |
| 131 | my $self = shift; | |
| 85253772 | 132 | if ($gas) { |
| 932cc129 | 133 | if ($self->{op} eq "movz") { # movz is pain... |
| 1cfd258e | 134 | sprintf "%s%s%s",$self->{op},$self->{sz},shift; |
| 932cc129 AP |
135 | } elsif ($self->{op} =~ /^set/) { |
| 136 | "$self->{op}"; | |
| 1cfd258e | 137 | } elsif ($self->{op} eq "ret") { |
| 85253772 AP |
138 | my $epilogue = ""; |
| 139 | if ($win64 && $current_function->{abi} eq "svr4") { | |
| 140 | $epilogue = "movq 8(%rsp),%rdi\n\t" . | |
| 141 | "movq 16(%rsp),%rsi\n\t"; | |
| 142 | } | |
| 143 | $epilogue . ".byte 0xf3,0xc3"; | |
| 144 | } elsif ($self->{op} eq "call" && !$elf && $current_segment eq ".init") { | |
| 145 | ".p2align\t3\n\t.quad"; | |
| 1cfd258e AP |
146 | } else { |
| 147 | "$self->{op}$self->{sz}"; | |
| 148 | } | |
| 149 | } else { | |
| a078befc | 150 | $self->{op} =~ s/^movz/movzx/; |
| 1cfd258e AP |
151 | if ($self->{op} eq "ret") { |
| 152 | $self->{op} = ""; | |
| 85253772 | 153 | if ($win64 && $current_function->{abi} eq "svr4") { |
| a23e3dbe AP |
154 | $self->{op} = "mov rdi,QWORD${PTR}[8+rsp]\t;WIN64 epilogue\n\t". |
| 155 | "mov rsi,QWORD${PTR}[16+rsp]\n\t"; | |
| 1cfd258e AP |
156 | } |
| 157 | $self->{op} .= "DB\t0F3h,0C3h\t\t;repret"; | |
| 85253772 | 158 | } elsif ($self->{op} =~ /^(pop|push)f/) { |
| 80aa9cc9 | 159 | $self->{op} .= $self->{sz}; |
| 85253772 AP |
160 | } elsif ($self->{op} eq "call" && $current_segment eq ".CRT\$XCU") { |
| 161 | $self->{op} = "ALIGN\t8\n\tDQ"; | |
| 162 | } | |
| 1cfd258e AP |
163 | $self->{op}; |
| 164 | } | |
| 165 | } | |
| 85253772 AP |
166 | sub mnemonic { |
| 167 | my $self=shift; | |
| 168 | my $op=shift; | |
| 169 | $self->{op}=$op if (defined($op)); | |
| 170 | $self->{op}; | |
| 171 | } | |
| 1cfd258e AP |
172 | } |
| 173 | { package const; # pick up constants, which start with $ | |
| 174 | sub re { | |
| 175 | my $self = shift; # single instance in enough... | |
| 176 | local *line = shift; | |
| 177 | undef $ret; | |
| 178 | ||
| 179 | if ($line =~ /^\$([^,]+)/) { | |
| 180 | $self->{value} = $1; | |
| 181 | $ret = $self; | |
| 182 | $line = substr($line,@+[0]); $line =~ s/^\s+//; | |
| 183 | } | |
| 184 | $ret; | |
| 185 | } | |
| 186 | sub out { | |
| 187 | my $self = shift; | |
| 5d0d60e2 | 188 | |
| 85253772 | 189 | if ($gas) { |
| e84b663a AP |
190 | # Solaris /usr/ccs/bin/as can't handle multiplications |
| 191 | # in $self->{value} | |
| 192 | $self->{value} =~ s/(?<![0-9a-f])(0[x0-9a-f]+)/oct($1)/egi; | |
| 193 | $self->{value} =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg; | |
| 5d0d60e2 AP |
194 | sprintf "\$%s",$self->{value}; |
| 195 | } else { | |
| 196 | $self->{value} =~ s/0x([0-9a-f]+)/0$1h/ig; | |
| 197 | sprintf "%s",$self->{value}; | |
| 198 | } | |
| 1cfd258e AP |
199 | } |
| 200 | } | |
| 201 | { package ea; # pick up effective addresses: expr(%reg,%reg,scale) | |
| 202 | sub re { | |
| 203 | my $self = shift; # single instance in enough... | |
| 204 | local *line = shift; | |
| 205 | undef $ret; | |
| 206 | ||
| 9b634c9b AP |
207 | # optional * ---vvv--- appears in indirect jmp/call |
| 208 | if ($line =~ /^(\*?)([^\(,]*)\(([%\w,]+)\)/) { | |
| 209 | $self->{asterisk} = $1; | |
| 210 | $self->{label} = $2; | |
| 211 | ($self->{base},$self->{index},$self->{scale})=split(/,/,$3); | |
| 1cfd258e AP |
212 | $self->{scale} = 1 if (!defined($self->{scale})); |
| 213 | $ret = $self; | |
| 214 | $line = substr($line,@+[0]); $line =~ s/^\s+//; | |
| 215 | ||
| 85253772 AP |
216 | if ($win64 && $self->{label} =~ s/\@GOTPCREL//) { |
| 217 | die if (opcode->mnemonic() ne "mov"); | |
| 218 | opcode->mnemonic("lea"); | |
| 219 | } | |
| 1cfd258e AP |
220 | $self->{base} =~ s/^%//; |
| 221 | $self->{index} =~ s/^%// if (defined($self->{index})); | |
| 222 | } | |
| 223 | $ret; | |
| 224 | } | |
| 225 | sub size {} | |
| 226 | sub out { | |
| 227 | my $self = shift; | |
| 228 | my $sz = shift; | |
| 229 | ||
| 85253772 AP |
230 | $self->{label} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei; |
| 231 | ||
| afbe674e AP |
232 | # Silently convert all EAs to 64-bit. This is required for |
| 233 | # elder GNU assembler and results in more compact code, | |
| 234 | # *but* most importantly AES module depends on this feature! | |
| 235 | $self->{index} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/; | |
| 236 | $self->{base} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/; | |
| 237 | ||
| 85253772 | 238 | if ($gas) { |
| e442c362 AP |
239 | # Solaris /usr/ccs/bin/as can't handle multiplications |
| 240 | # in $self->{label} | |
| e84b663a | 241 | $self->{label} =~ s/(?<![0-9a-f])(0[x0-9a-f]+)/oct($1)/egi; |
| e442c362 | 242 | $self->{label} =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg; |
| 85253772 | 243 | $self->{label} =~ s/\.L/L\$/g if (!$elf); |
| 4b450519 | 244 | |
| 1cfd258e | 245 | if (defined($self->{index})) { |
| 9b634c9b | 246 | sprintf "%s%s(%%%s,%%%s,%d)",$self->{asterisk}, |
| 70cf3095 | 247 | $self->{label},$self->{base}, |
| 1cfd258e | 248 | $self->{index},$self->{scale}; |
| 5d0d60e2 | 249 | } else { |
| 9b634c9b | 250 | sprintf "%s%s(%%%s)", $self->{asterisk},$self->{label},$self->{base}; |
| 1cfd258e AP |
251 | } |
| 252 | } else { | |
| a23e3dbe | 253 | %szmap = ( b=>"BYTE$PTR", w=>"WORD$PTR", l=>"DWORD$PTR", q=>"QWORD$PTR" ); |
| 1cfd258e | 254 | |
| 80aa9cc9 | 255 | $self->{label} =~ s/\.L/\$L\$/g; |
| 70cf3095 AP |
256 | $self->{label} =~ s/\./\$/g; |
| 257 | $self->{label} =~ s/0x([0-9a-f]+)/0$1h/ig; | |
| 258 | $self->{label} = "($self->{label})" if ($self->{label} =~ /[\*\+\-\/]/); | |
| 9b634c9b | 259 | $sz="q" if ($self->{asterisk}); |
| 70cf3095 | 260 | |
| 1cfd258e | 261 | if (defined($self->{index})) { |
| a23e3dbe AP |
262 | sprintf "%s[%s%s*%d+%s]",$szmap{$sz}, |
| 263 | $self->{label}?"$self->{label}+":"", | |
| 1cfd258e AP |
264 | $self->{index},$self->{scale}, |
| 265 | $self->{base}; | |
| 932cc129 | 266 | } elsif ($self->{base} eq "rip") { |
| a23e3dbe | 267 | sprintf "%s[%s]",$szmap{$sz},$self->{label}; |
| 5d0d60e2 | 268 | } else { |
| a23e3dbe AP |
269 | sprintf "%s[%s%s]",$szmap{$sz}, |
| 270 | $self->{label}?"$self->{label}+":"", | |
| 271 | $self->{base}; | |
| 1cfd258e AP |
272 | } |
| 273 | } | |
| 274 | } | |
| 275 | } | |
| 276 | { package register; # pick up registers, which start with %. | |
| 277 | sub re { | |
| 278 | my $class = shift; # muliple instances... | |
| 279 | my $self = {}; | |
| 280 | local *line = shift; | |
| 281 | undef $ret; | |
| 282 | ||
| 9b634c9b AP |
283 | # optional * ---vvv--- appears in indirect jmp/call |
| 284 | if ($line =~ /^(\*?)%(\w+)/) { | |
| 1cfd258e | 285 | bless $self,$class; |
| 9b634c9b AP |
286 | $self->{asterisk} = $1; |
| 287 | $self->{value} = $2; | |
| 1cfd258e AP |
288 | $ret = $self; |
| 289 | $line = substr($line,@+[0]); $line =~ s/^\s+//; | |
| 290 | } | |
| 291 | $ret; | |
| 292 | } | |
| 293 | sub size { | |
| 294 | my $self = shift; | |
| 295 | undef $ret; | |
| 296 | ||
| 297 | if ($self->{value} =~ /^r[\d]+b$/i) { $ret="b"; } | |
| 298 | elsif ($self->{value} =~ /^r[\d]+w$/i) { $ret="w"; } | |
| 299 | elsif ($self->{value} =~ /^r[\d]+d$/i) { $ret="l"; } | |
| 300 | elsif ($self->{value} =~ /^r[\w]+$/i) { $ret="q"; } | |
| 301 | elsif ($self->{value} =~ /^[a-d][hl]$/i){ $ret="b"; } | |
| 302 | elsif ($self->{value} =~ /^[\w]{2}l$/i) { $ret="b"; } | |
| 303 | elsif ($self->{value} =~ /^[\w]{2}$/i) { $ret="w"; } | |
| 304 | elsif ($self->{value} =~ /^e[a-z]{2}$/i){ $ret="l"; } | |
| 305 | ||
| 306 | $ret; | |
| 307 | } | |
| 308 | sub out { | |
| 309 | my $self = shift; | |
| 85253772 | 310 | if ($gas) { sprintf "%s%%%s",$self->{asterisk},$self->{value}; } |
| 9b634c9b | 311 | else { $self->{value}; } |
| 1cfd258e AP |
312 | } |
| 313 | } | |
| 314 | { package label; # pick up labels, which end with : | |
| 315 | sub re { | |
| 316 | my $self = shift; # single instance is enough... | |
| 317 | local *line = shift; | |
| 318 | undef $ret; | |
| 319 | ||
| 85253772 | 320 | if ($line =~ /(^[\.\w]+)\:/) { |
| 1cfd258e AP |
321 | $self->{value} = $1; |
| 322 | $ret = $self; | |
| 323 | $line = substr($line,@+[0]); $line =~ s/^\s+//; | |
| 324 | ||
| 85253772 AP |
325 | $self->{value} =~ s/\.L/\$L\$/ if (!$gas); |
| 326 | $self->{value} =~ s/\.L/L\$/ if (!$elf); | |
| 1cfd258e AP |
327 | } |
| 328 | $ret; | |
| 329 | } | |
| 330 | sub out { | |
| 331 | my $self = shift; | |
| 332 | ||
| 85253772 AP |
333 | if ($gas) { |
| 334 | my $func = ($globals{$self->{value}} or $self->{value}) . ":"; | |
| 335 | if ($win64 && | |
| 336 | $current_function->{name} eq $self->{value} && | |
| 337 | $current_function->{abi} eq "svr4") { | |
| 338 | $func .= "\n"; | |
| 339 | $func .= " movq %rdi,8(%rsp)\n"; | |
| 340 | $func .= " movq %rsi,16(%rsp)\n"; | |
| 341 | $func .= " movq %rsp,%rax\n"; | |
| 342 | $func .= ".LSEH_begin_$current_function->{name}:\n"; | |
| 343 | my $narg = $current_function->{narg}; | |
| 344 | $narg=6 if (!defined($narg)); | |
| 345 | $func .= " movq %rcx,%rdi\n" if ($narg>0); | |
| 346 | $func .= " movq %rdx,%rsi\n" if ($narg>1); | |
| 347 | $func .= " movq %r8,%rdx\n" if ($narg>2); | |
| 348 | $func .= " movq %r9,%rcx\n" if ($narg>3); | |
| 349 | $func .= " movq 40(%rsp),%r8\n" if ($narg>4); | |
| 350 | $func .= " movq 48(%rsp),%r9\n" if ($narg>5); | |
| 351 | } | |
| 352 | $func; | |
| 353 | } elsif ($self->{value} ne "$current_function->{name}") { | |
| 9b634c9b | 354 | $self->{value} .= ":" if ($masm && $ret!~m/^\$/); |
| 85253772 AP |
355 | $self->{value} . ":"; |
| 356 | } elsif ($win64 && $current_function->{abi} eq "svr4") { | |
| 9b634c9b AP |
357 | my $func = "$current_function->{name}" . |
| 358 | ($nasm ? ":" : "\tPROC $current_function->{scope}") . | |
| 359 | "\n"; | |
| 360 | $func .= " mov QWORD${PTR}[8+rsp],rdi\t;WIN64 prologue\n"; | |
| 361 | $func .= " mov QWORD${PTR}[16+rsp],rsi\n"; | |
| 80aa9cc9 AP |
362 | $func .= " mov rax,rsp\n"; |
| 363 | $func .= "\$L\$SEH_begin_$current_function->{name}:"; | |
| 364 | $func .= ":" if ($masm); | |
| 365 | $func .= "\n"; | |
| 1cfd258e AP |
366 | my $narg = $current_function->{narg}; |
| 367 | $narg=6 if (!defined($narg)); | |
| 368 | $func .= " mov rdi,rcx\n" if ($narg>0); | |
| 369 | $func .= " mov rsi,rdx\n" if ($narg>1); | |
| 370 | $func .= " mov rdx,r8\n" if ($narg>2); | |
| 371 | $func .= " mov rcx,r9\n" if ($narg>3); | |
| a23e3dbe AP |
372 | $func .= " mov r8,QWORD${PTR}[40+rsp]\n" if ($narg>4); |
| 373 | $func .= " mov r9,QWORD${PTR}[48+rsp]\n" if ($narg>5); | |
| 1cfd258e AP |
374 | $func .= "\n"; |
| 375 | } else { | |
| 9b634c9b AP |
376 | "$current_function->{name}". |
| 377 | ($nasm ? ":" : "\tPROC $current_function->{scope}"); | |
| 1cfd258e AP |
378 | } |
| 379 | } | |
| 380 | } | |
| 381 | { package expr; # pick up expressioins | |
| 382 | sub re { | |
| 383 | my $self = shift; # single instance is enough... | |
| 384 | local *line = shift; | |
| 385 | undef $ret; | |
| 386 | ||
| 387 | if ($line =~ /(^[^,]+)/) { | |
| 388 | $self->{value} = $1; | |
| 389 | $ret = $self; | |
| 390 | $line = substr($line,@+[0]); $line =~ s/^\s+//; | |
| 391 | ||
| 85253772 AP |
392 | $self->{value} =~ s/\@PLT// if (!$elf); |
| 393 | $self->{value} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei; | |
| 394 | $self->{value} =~ s/\.L/\$L\$/g if (!$gas); | |
| 395 | $self->{value} =~ s/\.L/L\$/g if (!$elf); | |
| 1cfd258e AP |
396 | } |
| 397 | $ret; | |
| 398 | } | |
| 399 | sub out { | |
| 400 | my $self = shift; | |
| 9b634c9b AP |
401 | if ($nasm && opcode->mnemonic()=~m/^j/) { |
| 402 | "NEAR ".$self->{value}; | |
| 403 | } else { | |
| 404 | $self->{value}; | |
| 405 | } | |
| 1cfd258e AP |
406 | } |
| 407 | } | |
| 408 | { package directive; # pick up directives, which start with . | |
| 409 | sub re { | |
| 410 | my $self = shift; # single instance is enough... | |
| 411 | local *line = shift; | |
| 412 | undef $ret; | |
| 413 | my $dir; | |
| 5d0d60e2 AP |
414 | my %opcode = # lea 2f-1f(%rip),%dst; 1: nop; 2: |
| 415 | ( "%rax"=>0x01058d48, "%rcx"=>0x010d8d48, | |
| 416 | "%rdx"=>0x01158d48, "%rbx"=>0x011d8d48, | |
| 417 | "%rsp"=>0x01258d48, "%rbp"=>0x012d8d48, | |
| 418 | "%rsi"=>0x01358d48, "%rdi"=>0x013d8d48, | |
| 419 | "%r8" =>0x01058d4c, "%r9" =>0x010d8d4c, | |
| 420 | "%r10"=>0x01158d4c, "%r11"=>0x011d8d4c, | |
| 421 | "%r12"=>0x01258d4c, "%r13"=>0x012d8d4c, | |
| 422 | "%r14"=>0x01358d4c, "%r15"=>0x013d8d4c ); | |
| 1cfd258e AP |
423 | |
| 424 | if ($line =~ /^\s*(\.\w+)/) { | |
| 85253772 AP |
425 | $dir = $1; |
| 426 | $ret = $self; | |
| 427 | undef $self->{value}; | |
| 428 | $line = substr($line,@+[0]); $line =~ s/^\s+//; | |
| 429 | ||
| 430 | SWITCH: for ($dir) { | |
| 431 | /\.picmeup/ && do { if ($line =~ /(%r[\w]+)/i) { | |
| 432 | $dir="\t.long"; | |
| 433 | $line=sprintf "0x%x,0x90000000",$opcode{$1}; | |
| 434 | } | |
| 435 | last; | |
| 436 | }; | |
| 437 | /\.global|\.globl|\.extern/ | |
| 438 | && do { $globals{$line} = $prefix . $line; | |
| 439 | $line = $globals{$line} if ($prefix); | |
| 440 | last; | |
| 441 | }; | |
| 442 | /\.type/ && do { ($sym,$type,$narg) = split(',',$line); | |
| 443 | if ($type eq "\@function") { | |
| 444 | undef $current_function; | |
| 445 | $current_function->{name} = $sym; | |
| 446 | $current_function->{abi} = "svr4"; | |
| 447 | $current_function->{narg} = $narg; | |
| 448 | $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE"; | |
| 449 | } elsif ($type eq "\@abi-omnipotent") { | |
| 450 | undef $current_function; | |
| 451 | $current_function->{name} = $sym; | |
| 452 | $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE"; | |
| 453 | } | |
| 454 | $line =~ s/\@abi\-omnipotent/\@function/; | |
| 455 | $line =~ s/\@function.*/\@function/; | |
| 456 | last; | |
| 457 | }; | |
| 458 | /\.asciz/ && do { if ($line =~ /^"(.*)"$/) { | |
| 459 | $dir = ".byte"; | |
| 460 | $line = join(",",unpack("C*",$1),0); | |
| 461 | } | |
| 462 | last; | |
| 463 | }; | |
| 464 | } | |
| 465 | ||
| 466 | if ($gas) { | |
| 467 | $self->{value} = $dir . "\t" . $line; | |
| 468 | ||
| 469 | if ($dir =~ /\.extern/) { | |
| 932cc129 | 470 | $self->{value} = ""; # swallow extern |
| 85253772 AP |
471 | } elsif (!$elf && $dir =~ /\.type/) { |
| 472 | $self->{value} = ""; | |
| 473 | $self->{value} = ".def\t" . ($globals{$1} or $1) . ";\t" . | |
| 474 | (defined($globals{$1})?".scl 2;":".scl 3;") . | |
| 475 | "\t.type 32;\t.endef" | |
| 476 | if ($win64 && $line =~ /([^,]+),\@function/); | |
| 477 | } elsif (!$elf && $dir =~ /\.size/) { | |
| 478 | $self->{value} = ""; | |
| 479 | if (defined($current_function)) { | |
| 480 | $self->{value} .= ".LSEH_end_$current_function->{name}:" | |
| 481 | if ($win64 && $current_function->{abi} eq "svr4"); | |
| 482 | undef $current_function; | |
| 483 | } | |
| 484 | } elsif (!$elf && $dir =~ /\.align/) { | |
| 485 | $self->{value} = ".p2align\t" . (log($line)/log(2)); | |
| 486 | } elsif ($dir eq ".section") { | |
| 487 | $current_segment=$line; | |
| 488 | if (!$elf && $current_segment eq ".init") { | |
| 489 | if ($flavour eq "macosx") { $self->{value} = ".mod_init_func"; } | |
| 490 | elsif ($flavour eq "mingw64") { $self->{value} = ".section\t.ctors"; } | |
| 491 | } | |
| 492 | } elsif ($dir =~ /\.(text|data)/) { | |
| 493 | $current_segment=".$1"; | |
| 5d0d60e2 | 494 | } |
| 1cfd258e AP |
495 | $line = ""; |
| 496 | return $self; | |
| 497 | } | |
| 498 | ||
| 85253772 | 499 | # non-gas case or nasm/masm |
| 1cfd258e | 500 | SWITCH: for ($dir) { |
| 9b634c9b | 501 | /\.text/ && do { my $v=undef; |
| a23e3dbe | 502 | if ($nasm) { |
| 9b634c9b | 503 | $v="section .text code align=64\n"; |
| a23e3dbe AP |
504 | } else { |
| 505 | $v="$current_segment\tENDS\n" if ($current_segment); | |
| 9b634c9b | 506 | $current_segment = ".text\$"; |
| a23e3dbe AP |
507 | $v.="$current_segment\tSEGMENT "; |
| 508 | $v.=$masm>=$masmref ? "ALIGN(64)" : "PAGE"; | |
| 509 | $v.=" 'CODE'"; | |
| 510 | } | |
| 1cfd258e AP |
511 | $self->{value} = $v; |
| 512 | last; | |
| 513 | }; | |
| 9b634c9b AP |
514 | /\.data/ && do { my $v=undef; |
| 515 | if ($nasm) { | |
| 516 | $v="section .data data align=8\n"; | |
| 517 | } else { | |
| 518 | $v="$current_segment\tENDS\n" if ($current_segment); | |
| 519 | $current_segment = "_DATA"; | |
| 520 | $v.="$current_segment\tSEGMENT"; | |
| 521 | } | |
| 522 | $self->{value} = $v; | |
| 523 | last; | |
| 524 | }; | |
| 525 | /\.section/ && do { my $v=undef; | |
| 85253772 AP |
526 | $line =~ s/([^,]*).*/$1/; |
| 527 | $line = ".CRT\$XCU" if ($line eq ".init"); | |
| 9b634c9b AP |
528 | if ($nasm) { |
| 529 | $v="section $line"; | |
| 530 | if ($line=~/\.([px])data/) { | |
| 531 | $v.=" rdata align="; | |
| 532 | $v.=$1 eq "p"? 4 : 8; | |
| 533 | } | |
| 534 | } else { | |
| 535 | $v="$current_segment\tENDS\n" if ($current_segment); | |
| 536 | $v.="$line\tSEGMENT"; | |
| 537 | if ($line=~/\.([px])data/) { | |
| 538 | $v.=" READONLY"; | |
| 539 | $v.=" ALIGN(".($1 eq "p" ? 4 : 8).")" if ($masm>=$masmref); | |
| 540 | } | |
| 541 | } | |
| 542 | $current_segment = $line; | |
| 543 | $self->{value} = $v; | |
| 544 | last; | |
| 545 | }; | |
| a23e3dbe | 546 | /\.extern/ && do { $self->{value} = "EXTERN\t".$line; |
| 9b634c9b AP |
547 | $self->{value} .= ":NEAR" if ($masm); |
| 548 | last; | |
| 549 | }; | |
| 80aa9cc9 AP |
550 | /\.globl|.global/ |
| 551 | && do { $self->{value} = $masm?"PUBLIC":"global"; | |
| 552 | $self->{value} .= "\t".$line; | |
| 1cfd258e AP |
553 | last; |
| 554 | }; | |
| 5d0d60e2 | 555 | /\.size/ && do { if (defined($current_function)) { |
| 8fe8bae1 AP |
556 | undef $self->{value}; |
| 557 | if ($current_function->{abi} eq "svr4") { | |
| 558 | $self->{value}="\$L\$SEH_end_$current_function->{name}:"; | |
| 559 | $self->{value}.=":\n" if($masm); | |
| 560 | } | |
| 561 | $self->{value}.="$current_function->{name}\tENDP" if($masm); | |
| 1cfd258e AP |
562 | undef $current_function; |
| 563 | } | |
| 564 | last; | |
| 565 | }; | |
| 566 | /\.align/ && do { $self->{value} = "ALIGN\t".$line; last; }; | |
| 85253772 | 567 | /\.(value|long|rva|quad)/ |
| 80aa9cc9 AP |
568 | && do { my $sz = substr($1,0,1); |
| 569 | my @arr = split(',',$line); | |
| 1cfd258e | 570 | my $last = pop(@arr); |
| a23e3dbe | 571 | my $conv = sub { my $var=shift; |
| 9b634c9b | 572 | $var=~s/0x([0-9a-f]+)/0$1h/ig; |
| 80aa9cc9 | 573 | $var=~s/\.L/\$L\$/g; |
| 85253772 | 574 | if ($sz eq "D" && ($current_segment=~/.[px]data/ || $dir eq ".rva")) |
| 80aa9cc9 | 575 | { $var=~s/([_a-z\$\@][_a-z0-9\$\@]*)/$nasm?"$1 wrt ..imagebase":"imagerel $1"/egi; } |
| 9b634c9b | 576 | $var; |
| a23e3dbe | 577 | }; |
| 1cfd258e | 578 | |
| 85253772 | 579 | $sz =~ tr/bvlrq/BWDDQ/; |
| 1cfd258e | 580 | $self->{value} = "\tD$sz\t"; |
| a23e3dbe AP |
581 | for (@arr) { $self->{value} .= &$conv($_).","; } |
| 582 | $self->{value} .= &$conv($last); | |
| 1cfd258e AP |
583 | last; |
| 584 | }; | |
| 85253772 AP |
585 | /\.byte/ && do { my @str=split(",",$line); |
| 586 | while ($#str>15) { | |
| 55eab3b7 | 587 | $self->{value}.="DB\t" |
| 85253772 AP |
588 | .join(",",@str[0..15])."\n"; |
| 589 | foreach (0..15) { shift @str; } | |
| d68ff710 | 590 | } |
| 85253772 AP |
591 | $self->{value}.="DB\t" |
| 592 | .join(",",@str) if (@str); | |
| d68ff710 AP |
593 | last; |
| 594 | }; | |
| 1cfd258e AP |
595 | } |
| 596 | $line = ""; | |
| 597 | } | |
| 598 | ||
| 599 | $ret; | |
| 600 | } | |
| 601 | sub out { | |
| 602 | my $self = shift; | |
| 603 | $self->{value}; | |
| 604 | } | |
| 605 | } | |
| 606 | ||
| 9b634c9b AP |
607 | if ($nasm) { |
| 608 | print <<___; | |
| 609 | default rel | |
| 9b634c9b AP |
610 | ___ |
| 611 | } elsif ($masm) { | |
| 612 | print <<___; | |
| 613 | OPTION DOTNAME | |
| 614 | ___ | |
| 615 | } | |
| 1cfd258e AP |
616 | while($line=<>) { |
| 617 | ||
| 618 | chomp($line); | |
| 619 | ||
| 4b450519 AP |
620 | $line =~ s|[#!].*$||; # get rid of asm-style comments... |
| 621 | $line =~ s|/\*.*\*/||; # ... and C-style comments... | |
| 622 | $line =~ s|^\s+||; # ... and skip white spaces in beginning | |
| 1cfd258e AP |
623 | |
| 624 | undef $label; | |
| 625 | undef $opcode; | |
| 626 | undef $dst; | |
| 627 | undef $src; | |
| 628 | undef $sz; | |
| 629 | ||
| 630 | if ($label=label->re(\$line)) { print $label->out(); } | |
| 631 | ||
| 632 | if (directive->re(\$line)) { | |
| 633 | printf "%s",directive->out(); | |
| 634 | } elsif ($opcode=opcode->re(\$line)) { ARGUMENT: { | |
| 635 | ||
| 636 | if ($src=register->re(\$line)) { opcode->size($src->size()); } | |
| 637 | elsif ($src=const->re(\$line)) { } | |
| 638 | elsif ($src=ea->re(\$line)) { } | |
| 639 | elsif ($src=expr->re(\$line)) { } | |
| 640 | ||
| 641 | last ARGUMENT if ($line !~ /^,/); | |
| 642 | ||
| 643 | $line = substr($line,1); $line =~ s/^\s+//; | |
| 644 | ||
| 645 | if ($dst=register->re(\$line)) { opcode->size($dst->size()); } | |
| 646 | elsif ($dst=const->re(\$line)) { } | |
| 647 | elsif ($dst=ea->re(\$line)) { } | |
| 648 | ||
| 649 | } # ARGUMENT: | |
| 650 | ||
| 651 | $sz=opcode->size(); | |
| 652 | ||
| 653 | if (defined($dst)) { | |
| 85253772 | 654 | if ($gas) { |
| 1cfd258e AP |
655 | printf "\t%s\t%s,%s", $opcode->out($dst->size()), |
| 656 | $src->out($sz),$dst->out($sz); | |
| 5d0d60e2 | 657 | } else { |
| a23e3dbe | 658 | undef $sz if ($nasm && $opcode->mnemonic() eq "lea"); |
| 1cfd258e AP |
659 | printf "\t%s\t%s,%s", $opcode->out(), |
| 660 | $dst->out($sz),$src->out($sz); | |
| 661 | } | |
| 5d0d60e2 | 662 | } elsif (defined($src)) { |
| 1cfd258e AP |
663 | printf "\t%s\t%s",$opcode->out(),$src->out($sz); |
| 664 | } else { | |
| 665 | printf "\t%s",$opcode->out(); | |
| 666 | } | |
| 667 | } | |
| 668 | ||
| 669 | print $line,"\n"; | |
| 670 | } | |
| 671 | ||
| 85253772 AP |
672 | print "\n$current_segment\tENDS\n" if ($current_segment && $masm); |
| 673 | print "END\n" if ($masm); | |
| 1cfd258e AP |
674 | |
| 675 | close STDOUT; | |
| 676 | ||
| 80aa9cc9 | 677 | \f################################################# |
| 1cfd258e AP |
678 | # Cross-reference x86_64 ABI "card" |
| 679 | # | |
| 680 | # Unix Win64 | |
| 681 | # %rax * * | |
| 682 | # %rbx - - | |
| 683 | # %rcx #4 #1 | |
| 684 | # %rdx #3 #2 | |
| 685 | # %rsi #2 - | |
| 686 | # %rdi #1 - | |
| 687 | # %rbp - - | |
| 688 | # %rsp - - | |
| 689 | # %r8 #5 #3 | |
| 690 | # %r9 #6 #4 | |
| 691 | # %r10 * * | |
| 692 | # %r11 * * | |
| 693 | # %r12 - - | |
| 694 | # %r13 - - | |
| 695 | # %r14 - - | |
| 696 | # %r15 - - | |
| 697 | # | |
| 698 | # (*) volatile register | |
| 699 | # (-) preserved by callee | |
| 700 | # (#) Nth argument, volatile | |
| 701 | # | |
| 702 | # In Unix terms top of stack is argument transfer area for arguments | |
| 703 | # which could not be accomodated in registers. Or in other words 7th | |
| 704 | # [integer] argument resides at 8(%rsp) upon function entry point. | |
| 705 | # 128 bytes above %rsp constitute a "red zone" which is not touched | |
| 706 | # by signal handlers and can be used as temporal storage without | |
| 707 | # allocating a frame. | |
| 708 | # | |
| 709 | # In Win64 terms N*8 bytes on top of stack is argument transfer area, | |
| 710 | # which belongs to/can be overwritten by callee. N is the number of | |
| 711 | # arguments passed to callee, *but* not less than 4! This means that | |
| 712 | # upon function entry point 5th argument resides at 40(%rsp), as well | |
| 713 | # as that 32 bytes from 8(%rsp) can always be used as temporal | |
| d256b957 AP |
714 | # storage [without allocating a frame]. One can actually argue that |
| 715 | # one can assume a "red zone" above stack pointer under Win64 as well. | |
| 6a3a7f30 AP |
716 | # Point is that at apparently no occasion Windows kernel would alter |
| 717 | # the area above user stack pointer in true asynchronous manner... | |
| 1cfd258e AP |
718 | # |
| 719 | # All the above means that if assembler programmer adheres to Unix | |
| 720 | # register and stack layout, but disregards the "red zone" existense, | |
| 721 | # it's possible to use following prologue and epilogue to "gear" from | |
| 722 | # Unix to Win64 ABI in leaf functions with not more than 6 arguments. | |
| 723 | # | |
| 724 | # omnipotent_function: | |
| 725 | # ifdef WIN64 | |
| 726 | # movq %rdi,8(%rsp) | |
| 727 | # movq %rsi,16(%rsp) | |
| 728 | # movq %rcx,%rdi ; if 1st argument is actually present | |
| 729 | # movq %rdx,%rsi ; if 2nd argument is actually ... | |
| 730 | # movq %r8,%rdx ; if 3rd argument is ... | |
| 731 | # movq %r9,%rcx ; if 4th argument ... | |
| 732 | # movq 40(%rsp),%r8 ; if 5th ... | |
| 733 | # movq 48(%rsp),%r9 ; if 6th ... | |
| 734 | # endif | |
| 735 | # ... | |
| 736 | # ifdef WIN64 | |
| 737 | # movq 8(%rsp),%rdi | |
| 738 | # movq 16(%rsp),%rsi | |
| 739 | # endif | |
| 740 | # ret | |
| 4f469342 | 741 | # |
| 80aa9cc9 AP |
742 | \f################################################# |
| 743 | # Win64 SEH, Structured Exception Handling. | |
| 744 | # | |
| 4f469342 AP |
745 | # Unlike on Unix systems(*) lack of Win64 stack unwinding information |
| 746 | # has undesired side-effect at run-time: if an exception is raised in | |
| 747 | # assembler subroutine such as those in question (basically we're | |
| 748 | # referring to segmentation violations caused by malformed input | |
| 749 | # parameters), the application is briskly terminated without invoking | |
| 750 | # any exception handlers, most notably without generating memory dump | |
| 751 | # or any user notification whatsoever. This poses a problem. It's | |
| 752 | # possible to address it by registering custom language-specific | |
| 753 | # handler that would restore processor context to the state at | |
| 754 | # subroutine entry point and return "exception is not handled, keep | |
| 755 | # unwinding" code. Writing such handler can be a challenge... But it's | |
| 756 | # doable, though requires certain coding convention. Consider following | |
| 757 | # snippet: | |
| 758 | # | |
| 80aa9cc9 | 759 | # .type function,@function |
| 4f469342 AP |
760 | # function: |
| 761 | # movq %rsp,%rax # copy rsp to volatile register | |
| 762 | # pushq %r15 # save non-volatile registers | |
| 763 | # pushq %rbx | |
| 764 | # pushq %rbp | |
| 765 | # movq %rsp,%r11 | |
| 766 | # subq %rdi,%r11 # prepare [variable] stack frame | |
| 767 | # andq $-64,%r11 | |
| 768 | # movq %rax,0(%r11) # check for exceptions | |
| 769 | # movq %r11,%rsp # allocate [variable] stack frame | |
| 770 | # movq %rax,0(%rsp) # save original rsp value | |
| 771 | # magic_point: | |
| 772 | # ... | |
| 773 | # movq 0(%rsp),%rcx # pull original rsp value | |
| 774 | # movq -24(%rcx),%rbp # restore non-volatile registers | |
| 775 | # movq -16(%rcx),%rbx | |
| 776 | # movq -8(%rcx),%r15 | |
| 777 | # movq %rcx,%rsp # restore original rsp | |
| 778 | # ret | |
| 80aa9cc9 | 779 | # .size function,.-function |
| 4f469342 AP |
780 | # |
| 781 | # The key is that up to magic_point copy of original rsp value remains | |
| 782 | # in chosen volatile register and no non-volatile register, except for | |
| 783 | # rsp, is modified. While past magic_point rsp remains constant till | |
| 784 | # the very end of the function. In this case custom language-specific | |
| 785 | # exception handler would look like this: | |
| 786 | # | |
| 787 | # EXCEPTION_DISPOSITION handler (EXCEPTION_RECORD *rec,ULONG64 frame, | |
| 788 | # CONTEXT *context,DISPATCHER_CONTEXT *disp) | |
| 80aa9cc9 AP |
789 | # { ULONG64 *rsp = (ULONG64 *)context->Rax; |
| 790 | # if (context->Rip >= magic_point) | |
| 4f469342 AP |
791 | # { rsp = ((ULONG64 **)context->Rsp)[0]; |
| 792 | # context->Rbp = rsp[-3]; | |
| 793 | # context->Rbx = rsp[-2]; | |
| 794 | # context->R15 = rsp[-1]; | |
| 795 | # } | |
| 796 | # context->Rsp = (ULONG64)rsp; | |
| 797 | # context->Rdi = rsp[1]; | |
| 798 | # context->Rsi = rsp[2]; | |
| 799 | # | |
| 800 | # memcpy (disp->ContextRecord,context,sizeof(CONTEXT)); | |
| 801 | # RtlVirtualUnwind(UNW_FLAG_NHANDLER,disp->ImageBase, | |
| 802 | # dips->ControlPc,disp->FunctionEntry,disp->ContextRecord, | |
| 803 | # &disp->HandlerData,&disp->EstablisherFrame,NULL); | |
| 804 | # return ExceptionContinueSearch; | |
| 805 | # } | |
| 806 | # | |
| 807 | # It's appropriate to implement this handler in assembler, directly in | |
| 808 | # function's module. In order to do that one has to know members' | |
| 809 | # offsets in CONTEXT and DISPATCHER_CONTEXT structures and some constant | |
| 810 | # values. Here they are: | |
| 811 | # | |
| 812 | # CONTEXT.Rax 120 | |
| 813 | # CONTEXT.Rcx 128 | |
| 814 | # CONTEXT.Rdx 136 | |
| 815 | # CONTEXT.Rbx 144 | |
| 816 | # CONTEXT.Rsp 152 | |
| 817 | # CONTEXT.Rbp 160 | |
| 818 | # CONTEXT.Rsi 168 | |
| 819 | # CONTEXT.Rdi 176 | |
| 820 | # CONTEXT.R8 184 | |
| 821 | # CONTEXT.R9 192 | |
| 822 | # CONTEXT.R10 200 | |
| 823 | # CONTEXT.R11 208 | |
| 824 | # CONTEXT.R12 216 | |
| 825 | # CONTEXT.R13 224 | |
| 826 | # CONTEXT.R14 232 | |
| 827 | # CONTEXT.R15 240 | |
| 828 | # CONTEXT.Rip 248 | |
| 829 | # sizeof(CONTEXT) 1232 | |
| 830 | # DISPATCHER_CONTEXT.ControlPc 0 | |
| 831 | # DISPATCHER_CONTEXT.ImageBase 8 | |
| 832 | # DISPATCHER_CONTEXT.FunctionEntry 16 | |
| 833 | # DISPATCHER_CONTEXT.EstablisherFrame 24 | |
| 834 | # DISPATCHER_CONTEXT.TargetIp 32 | |
| 835 | # DISPATCHER_CONTEXT.ContextRecord 40 | |
| 836 | # DISPATCHER_CONTEXT.LanguageHandler 48 | |
| 837 | # DISPATCHER_CONTEXT.HandlerData 56 | |
| 838 | # UNW_FLAG_NHANDLER 0 | |
| 839 | # ExceptionContinueSearch 1 | |
| 840 | # | |
| 80aa9cc9 AP |
841 | # In order to tie the handler to the function one has to compose |
| 842 | # couple of structures: one for .xdata segment and one for .pdata. | |
| 843 | # | |
| 4f469342 | 844 | # UNWIND_INFO structure for .xdata segment would be |
| 80aa9cc9 AP |
845 | # |
| 846 | # function_unwind_info: | |
| 847 | # .byte 9,0,0,0 | |
| 85253772 | 848 | # .rva handler |
| 80aa9cc9 AP |
849 | # |
| 850 | # This structure designates exception handler for a function with | |
| 851 | # zero-length prologue, no stack frame or frame register. | |
| 852 | # | |
| 853 | # To facilitate composing of .pdata structures, auto-generated "gear" | |
| 854 | # prologue copies rsp value to rax and denotes next instruction with | |
| 85253772 | 855 | # .LSEH_begin_{function_name} label. This essentially defines the SEH |
| 80aa9cc9 AP |
856 | # styling rule mentioned in the beginning. Position of this label is |
| 857 | # chosen in such manner that possible exceptions raised in the "gear" | |
| 858 | # prologue would be accounted to caller and unwound from latter's frame. | |
| 85253772 | 859 | # End of function is marked with respective .LSEH_end_{function_name} |
| 80aa9cc9 AP |
860 | # label. To summarize, .pdata segment would contain |
| 861 | # | |
| 85253772 AP |
862 | # .rva .LSEH_begin_function |
| 863 | # .rva .LSEH_end_function | |
| 864 | # .rva function_unwind_info | |
| 80aa9cc9 AP |
865 | # |
| 866 | # Reference to functon_unwind_info from .xdata segment is the anchor. | |
| 85253772 | 867 | # In case you wonder why references are 32-bit .rvas and not 64-bit |
| 80aa9cc9 AP |
868 | # .quads. References put into these two segments are required to be |
| 869 | # *relative* to the base address of the current binary module, a.k.a. | |
| 870 | # image base. No Win64 module, be it .exe or .dll, can be larger than | |
| 871 | # 2GB and thus such relative references can be and are accommodated in | |
| 872 | # 32 bits. | |
| 873 | # | |
| 874 | # Having reviewed the example function code, one can argue that "movq | |
| 875 | # %rsp,%rax" above is redundant. It is not! Keep in mind that on Unix | |
| 876 | # rax would contain an undefined value. If this "offends" you, use | |
| 877 | # another register and refrain from modifying rax till magic_point is | |
| 878 | # reached, i.e. as if it was a non-volatile register. If more registers | |
| 879 | # are required prior [variable] frame setup is completed, note that | |
| 880 | # nobody says that you can have only one "magic point." You can | |
| 881 | # "liberate" non-volatile registers by denoting last stack off-load | |
| 882 | # instruction and reflecting it in finer grade unwind logic in handler. | |
| 883 | # After all, isn't it why it's called *language-specific* handler... | |
| 884 | # | |
| 885 | # Attentive reader can notice that exceptions would be mishandled in | |
| 886 | # auto-generated "gear" epilogue. Well, exception effectively can't | |
| 887 | # occur there, because if memory area used by it was subject to | |
| 888 | # segmentation violation, then it would be raised upon call to the | |
| 889 | # function (and as already mentioned be accounted to caller, which is | |
| 890 | # not a problem). If you're still not comfortable, then define tail | |
| 891 | # "magic point" just prior ret instruction and have handler treat it... | |
| 4f469342 AP |
892 | # |
| 893 | # (*) Note that we're talking about run-time, not debug-time. Lack of | |
| 894 | # unwind information makes debugging hard on both Windows and | |
| 895 | # Unix. "Unlike" referes to the fact that on Unix signal handler | |
| 896 | # will always be invoked, core dumped and appropriate exit code | |
| 897 | # returned to parent (for user notification). |