| #! /usr/bin/env perl |
| # Copyright 2005-2016 The OpenSSL Project Authors. All Rights Reserved. |
| # |
| # Licensed under the OpenSSL license (the "License"). You may not use |
| # this file except in compliance with the License. You can obtain a copy |
| # in the file LICENSE in the source distribution or at |
| # https://www.openssl.org/source/license.html |
| |
| |
| # Ascetic x86_64 AT&T to MASM/NASM assembler translator by <appro>. |
| # |
| # Why AT&T to MASM and not vice versa? Several reasons. Because AT&T |
| # format is way easier to parse. Because it's simpler to "gear" from |
| # Unix ABI to Windows one [see cross-reference "card" at the end of |
| # file]. Because Linux targets were available first... |
| # |
| # In addition the script also "distills" code suitable for GNU |
| # assembler, so that it can be compiled with more rigid assemblers, |
| # such as Solaris /usr/ccs/bin/as. |
| # |
| # This translator is not designed to convert *arbitrary* assembler |
| # code from AT&T format to MASM one. It's designed to convert just |
| # enough to provide for dual-ABI OpenSSL modules development... |
| # There *are* limitations and you might have to modify your assembler |
| # code or this script to achieve the desired result... |
| # |
| # Currently recognized limitations: |
| # |
| # - can't use multiple ops per line; |
| # |
| # Dual-ABI styling rules. |
| # |
| # 1. Adhere to Unix register and stack layout [see cross-reference |
| # ABI "card" at the end for explanation]. |
| # 2. Forget about "red zone," stick to more traditional blended |
| # stack frame allocation. If volatile storage is actually required |
| # that is. If not, just leave the stack as is. |
| # 3. Functions tagged with ".type name,@function" get crafted with |
| # unified Win64 prologue and epilogue automatically. If you want |
| # to take care of ABI differences yourself, tag functions as |
| # ".type name,@abi-omnipotent" instead. |
| # 4. To optimize the Win64 prologue you can specify number of input |
| # arguments as ".type name,@function,N." Keep in mind that if N is |
| # larger than 6, then you *have to* write "abi-omnipotent" code, |
| # because >6 cases can't be addressed with unified prologue. |
| # 5. Name local labels as .L*, do *not* use dynamic labels such as 1: |
| # (sorry about latter). |
| # 6. Don't use [or hand-code with .byte] "rep ret." "ret" mnemonic is |
| # required to identify the spots, where to inject Win64 epilogue! |
| # But on the pros, it's then prefixed with rep automatically:-) |
| # 7. Stick to explicit ip-relative addressing. If you have to use |
| # GOTPCREL addressing, stick to mov symbol@GOTPCREL(%rip),%r??. |
| # Both are recognized and translated to proper Win64 addressing |
| # modes. To support legacy code a synthetic directive, .picmeup, |
| # is implemented. It puts address of the *next* instruction into |
| # target register, e.g.: |
| # |
| # .picmeup %rax |
| # lea .Label-.(%rax),%rax |
| # |
| # 8. In order to provide for structured exception handling unified |
| # Win64 prologue copies %rsp value to %rax. For further details |
| # see SEH paragraph at the end. |
| # 9. .init segment is allowed to contain calls to functions only. |
| # a. If function accepts more than 4 arguments *and* >4th argument |
| # is declared as non 64-bit value, do clear its upper part. |
| |
| |
| use strict; |
| |
| my $flavour = shift; |
| my $output = shift; |
| if ($flavour =~ /\./) { $output = $flavour; undef $flavour; } |
| |
| open STDOUT,">$output" || die "can't open $output: $!" |
| if (defined($output)); |
| |
| my $gas=1; $gas=0 if ($output =~ /\.asm$/); |
| my $elf=1; $elf=0 if (!$gas); |
| my $win64=0; |
| my $prefix=""; |
| my $decor=".L"; |
| |
| my $masmref=8 + 50727*2**-32; # 8.00.50727 shipped with VS2005 |
| my $masm=0; |
| my $PTR=" PTR"; |
| |
| my $nasmref=2.03; |
| my $nasm=0; |
| |
| if ($flavour eq "mingw64") { $gas=1; $elf=0; $win64=1; |
| # TODO(davidben): Before supporting the |
| # mingw64 perlasm flavour, do away with this |
| # environment variable check. |
| die "mingw64 not supported"; |
| $prefix=`echo __USER_LABEL_PREFIX__ | $ENV{CC} -E -P -`; |
| $prefix =~ s|\R$||; # Better chomp |
| } |
| elsif ($flavour eq "macosx") { $gas=1; $elf=0; $prefix="_"; $decor="L\$"; } |
| elsif ($flavour eq "masm") { $gas=0; $elf=0; $masm=$masmref; $win64=1; $decor="\$L\$"; } |
| elsif ($flavour eq "nasm") { $gas=0; $elf=0; $nasm=$nasmref; $win64=1; $decor="\$L\$"; $PTR=""; } |
| elsif (!$gas) { die "unknown flavour $flavour"; } |
| |
| my $current_segment; |
| my $current_function; |
| my %globals; |
| |
| { package opcode; # pick up opcodes |
| sub re { |
| my ($class, $line) = @_; |
| my $self = {}; |
| my $ret; |
| |
| if ($$line =~ /^([a-z][a-z0-9]*)/i) { |
| bless $self,$class; |
| $self->{op} = $1; |
| $ret = $self; |
| $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; |
| |
| undef $self->{sz}; |
| if ($self->{op} =~ /^(movz)x?([bw]).*/) { # movz is pain... |
| $self->{op} = $1; |
| $self->{sz} = $2; |
| } elsif ($self->{op} =~ /call|jmp/) { |
| $self->{sz} = ""; |
| } elsif ($self->{op} =~ /^p/ && $' !~ /^(ush|op|insrw)/) { # SSEn |
| $self->{sz} = ""; |
| } elsif ($self->{op} =~ /^v/) { # VEX |
| $self->{sz} = ""; |
| } elsif ($self->{op} =~ /mov[dq]/ && $$line =~ /%xmm/) { |
| $self->{sz} = ""; |
| } elsif ($self->{op} =~ /([a-z]{3,})([qlwb])$/) { |
| $self->{op} = $1; |
| $self->{sz} = $2; |
| } |
| } |
| $ret; |
| } |
| sub size { |
| my ($self, $sz) = @_; |
| $self->{sz} = $sz if (defined($sz) && !defined($self->{sz})); |
| $self->{sz}; |
| } |
| sub out { |
| my $self = shift; |
| if ($gas) { |
| if ($self->{op} eq "movz") { # movz is pain... |
| sprintf "%s%s%s",$self->{op},$self->{sz},shift; |
| } elsif ($self->{op} =~ /^set/) { |
| "$self->{op}"; |
| } elsif ($self->{op} eq "ret") { |
| my $epilogue = ""; |
| if ($win64 && $current_function->{abi} eq "svr4") { |
| $epilogue = "movq 8(%rsp),%rdi\n\t" . |
| "movq 16(%rsp),%rsi\n\t"; |
| } |
| $epilogue . ".byte 0xf3,0xc3"; |
| } elsif ($self->{op} eq "call" && !$elf && $current_segment eq ".init") { |
| ".p2align\t3\n\t.quad"; |
| } else { |
| "$self->{op}$self->{sz}"; |
| } |
| } else { |
| $self->{op} =~ s/^movz/movzx/; |
| if ($self->{op} eq "ret") { |
| $self->{op} = ""; |
| if ($win64 && $current_function->{abi} eq "svr4") { |
| $self->{op} = "mov rdi,QWORD$PTR\[8+rsp\]\t;WIN64 epilogue\n\t". |
| "mov rsi,QWORD$PTR\[16+rsp\]\n\t"; |
| } |
| $self->{op} .= "DB\t0F3h,0C3h\t\t;repret"; |
| } elsif ($self->{op} =~ /^(pop|push)f/) { |
| $self->{op} .= $self->{sz}; |
| } elsif ($self->{op} eq "call" && $current_segment eq ".CRT\$XCU") { |
| $self->{op} = "\tDQ"; |
| } |
| $self->{op}; |
| } |
| } |
| sub mnemonic { |
| my ($self, $op) = @_; |
| $self->{op}=$op if (defined($op)); |
| $self->{op}; |
| } |
| } |
| { package const; # pick up constants, which start with $ |
| sub re { |
| my ($class, $line) = @_; |
| my $self = {}; |
| my $ret; |
| |
| if ($$line =~ /^\$([^,]+)/) { |
| bless $self, $class; |
| $self->{value} = $1; |
| $ret = $self; |
| $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; |
| } |
| $ret; |
| } |
| sub out { |
| my $self = shift; |
| |
| $self->{value} =~ s/\b(0b[0-1]+)/oct($1)/eig; |
| if ($gas) { |
| # Solaris /usr/ccs/bin/as can't handle multiplications |
| # in $self->{value} |
| my $value = $self->{value}; |
| no warnings; # oct might complain about overflow, ignore here... |
| $value =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi; |
| if ($value =~ s/([0-9]+\s*[\*\/\%]\s*[0-9]+)/eval($1)/eg) { |
| $self->{value} = $value; |
| } |
| sprintf "\$%s",$self->{value}; |
| } else { |
| $self->{value} =~ s/0x([0-9a-f]+)/0$1h/ig if ($masm); |
| sprintf "%s",$self->{value}; |
| } |
| } |
| } |
| { package ea; # pick up effective addresses: expr(%reg,%reg,scale) |
| sub re { |
| my ($class, $line, $opcode) = @_; |
| my $self = {}; |
| my $ret; |
| |
| # optional * ----vvv--- appears in indirect jmp/call |
| if ($$line =~ /^(\*?)([^\(,]*)\(([%\w,]+)\)/) { |
| bless $self, $class; |
| $self->{asterisk} = $1; |
| $self->{label} = $2; |
| ($self->{base},$self->{index},$self->{scale})=split(/,/,$3); |
| $self->{scale} = 1 if (!defined($self->{scale})); |
| $ret = $self; |
| $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; |
| |
| if ($win64 && $self->{label} =~ s/\@GOTPCREL//) { |
| die if ($opcode->mnemonic() ne "mov"); |
| $opcode->mnemonic("lea"); |
| } |
| $self->{base} =~ s/^%//; |
| $self->{index} =~ s/^%// if (defined($self->{index})); |
| $self->{opcode} = $opcode; |
| } |
| $ret; |
| } |
| sub size {} |
| sub out { |
| my ($self, $sz) = @_; |
| |
| $self->{label} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei; |
| $self->{label} =~ s/\.L/$decor/g; |
| |
| # Silently convert all EAs to 64-bit. This is required for |
| # elder GNU assembler and results in more compact code, |
| # *but* most importantly AES module depends on this feature! |
| $self->{index} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/; |
| $self->{base} =~ s/^[er](.?[0-9xpi])[d]?$/r\1/; |
| |
| # Solaris /usr/ccs/bin/as can't handle multiplications |
| # in $self->{label}... |
| use integer; |
| $self->{label} =~ s/(?<![\w\$\.])(0x?[0-9a-f]+)/oct($1)/egi; |
| $self->{label} =~ s/\b([0-9]+\s*[\*\/\%]\s*[0-9]+)\b/eval($1)/eg; |
| |
| # Some assemblers insist on signed presentation of 32-bit |
| # offsets, but sign extension is a tricky business in perl... |
| if ((1<<31)<<1) { |
| $self->{label} =~ s/\b([0-9]+)\b/$1<<32>>32/eg; |
| } else { |
| $self->{label} =~ s/\b([0-9]+)\b/$1>>0/eg; |
| } |
| |
| if (!$self->{label} && $self->{index} && $self->{scale}==1 && |
| $self->{base} =~ /(rbp|r13)/) { |
| $self->{base} = $self->{index}; $self->{index} = $1; |
| } |
| |
| if ($gas) { |
| $self->{label} =~ s/^___imp_/__imp__/ if ($flavour eq "mingw64"); |
| |
| if (defined($self->{index})) { |
| sprintf "%s%s(%s,%%%s,%d)",$self->{asterisk}, |
| $self->{label}, |
| $self->{base}?"%$self->{base}":"", |
| $self->{index},$self->{scale}; |
| } else { |
| sprintf "%s%s(%%%s)", $self->{asterisk},$self->{label},$self->{base}; |
| } |
| } else { |
| my %szmap = ( b=>"BYTE$PTR", w=>"WORD$PTR", |
| l=>"DWORD$PTR", d=>"DWORD$PTR", |
| q=>"QWORD$PTR", o=>"OWORD$PTR", |
| x=>"XMMWORD$PTR", y=>"YMMWORD$PTR", z=>"ZMMWORD$PTR" ); |
| |
| $self->{label} =~ s/\./\$/g; |
| $self->{label} =~ s/(?<![\w\$\.])0x([0-9a-f]+)/0$1h/ig; |
| $self->{label} = "($self->{label})" if ($self->{label} =~ /[\*\+\-\/]/); |
| |
| my $mnemonic = $self->{opcode}->mnemonic(); |
| ($self->{asterisk}) && ($sz="q") || |
| ($mnemonic =~ /^v?mov([qd])$/) && ($sz=$1) || |
| ($mnemonic =~ /^v?pinsr([qdwb])$/) && ($sz=$1) || |
| ($mnemonic =~ /^vpbroadcast([qdwb])$/) && ($sz=$1) || |
| ($mnemonic =~ /^v(?!perm)[a-z]+[fi]128$/) && ($sz="x"); |
| |
| if (defined($self->{index})) { |
| sprintf "%s[%s%s*%d%s]",$szmap{$sz}, |
| $self->{label}?"$self->{label}+":"", |
| $self->{index},$self->{scale}, |
| $self->{base}?"+$self->{base}":""; |
| } elsif ($self->{base} eq "rip") { |
| sprintf "%s[%s]",$szmap{$sz},$self->{label}; |
| } else { |
| sprintf "%s[%s%s]",$szmap{$sz}, |
| $self->{label}?"$self->{label}+":"", |
| $self->{base}; |
| } |
| } |
| } |
| } |
| { package register; # pick up registers, which start with %. |
| sub re { |
| my ($class, $line, $opcode) = @_; |
| my $self = {}; |
| my $ret; |
| |
| # optional * ----vvv--- appears in indirect jmp/call |
| if ($$line =~ /^(\*?)%(\w+)/) { |
| bless $self,$class; |
| $self->{asterisk} = $1; |
| $self->{value} = $2; |
| $opcode->size($self->size()); |
| $ret = $self; |
| $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; |
| } |
| $ret; |
| } |
| sub size { |
| my $self = shift; |
| my $ret; |
| |
| if ($self->{value} =~ /^r[\d]+b$/i) { $ret="b"; } |
| elsif ($self->{value} =~ /^r[\d]+w$/i) { $ret="w"; } |
| elsif ($self->{value} =~ /^r[\d]+d$/i) { $ret="l"; } |
| elsif ($self->{value} =~ /^r[\w]+$/i) { $ret="q"; } |
| elsif ($self->{value} =~ /^[a-d][hl]$/i){ $ret="b"; } |
| elsif ($self->{value} =~ /^[\w]{2}l$/i) { $ret="b"; } |
| elsif ($self->{value} =~ /^[\w]{2}$/i) { $ret="w"; } |
| elsif ($self->{value} =~ /^e[a-z]{2}$/i){ $ret="l"; } |
| |
| $ret; |
| } |
| sub out { |
| my $self = shift; |
| if ($gas) { sprintf "%s%%%s",$self->{asterisk},$self->{value}; } |
| else { $self->{value}; } |
| } |
| } |
| { package label; # pick up labels, which end with : |
| sub re { |
| my ($class, $line) = @_; |
| my $self = {}; |
| my $ret; |
| |
| if ($$line =~ /(^[\.\w]+)\:/) { |
| bless $self,$class; |
| $self->{value} = $1; |
| $ret = $self; |
| $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; |
| |
| $self->{value} =~ s/^\.L/$decor/; |
| } |
| $ret; |
| } |
| sub out { |
| my $self = shift; |
| |
| if ($gas) { |
| my $func = ($globals{$self->{value}} or $self->{value}) . ":"; |
| if ($win64 && |
| $current_function->{name} eq $self->{value} && |
| $current_function->{abi} eq "svr4") { |
| $func .= "\n"; |
| $func .= " movq %rdi,8(%rsp)\n"; |
| $func .= " movq %rsi,16(%rsp)\n"; |
| $func .= " movq %rsp,%rax\n"; |
| $func .= "${decor}SEH_begin_$current_function->{name}:\n"; |
| my $narg = $current_function->{narg}; |
| $narg=6 if (!defined($narg)); |
| $func .= " movq %rcx,%rdi\n" if ($narg>0); |
| $func .= " movq %rdx,%rsi\n" if ($narg>1); |
| $func .= " movq %r8,%rdx\n" if ($narg>2); |
| $func .= " movq %r9,%rcx\n" if ($narg>3); |
| $func .= " movq 40(%rsp),%r8\n" if ($narg>4); |
| $func .= " movq 48(%rsp),%r9\n" if ($narg>5); |
| } |
| $func; |
| } elsif ($self->{value} ne "$current_function->{name}") { |
| # Make all labels in masm global. |
| $self->{value} .= ":" if ($masm); |
| $self->{value} . ":"; |
| } elsif ($win64 && $current_function->{abi} eq "svr4") { |
| my $func = "$current_function->{name}" . |
| ($nasm ? ":" : "\tPROC $current_function->{scope}") . |
| "\n"; |
| $func .= " mov QWORD$PTR\[8+rsp\],rdi\t;WIN64 prologue\n"; |
| $func .= " mov QWORD$PTR\[16+rsp\],rsi\n"; |
| $func .= " mov rax,rsp\n"; |
| $func .= "${decor}SEH_begin_$current_function->{name}:"; |
| $func .= ":" if ($masm); |
| $func .= "\n"; |
| my $narg = $current_function->{narg}; |
| $narg=6 if (!defined($narg)); |
| $func .= " mov rdi,rcx\n" if ($narg>0); |
| $func .= " mov rsi,rdx\n" if ($narg>1); |
| $func .= " mov rdx,r8\n" if ($narg>2); |
| $func .= " mov rcx,r9\n" if ($narg>3); |
| $func .= " mov r8,QWORD$PTR\[40+rsp\]\n" if ($narg>4); |
| $func .= " mov r9,QWORD$PTR\[48+rsp\]\n" if ($narg>5); |
| $func .= "\n"; |
| } else { |
| "$current_function->{name}". |
| ($nasm ? ":" : "\tPROC $current_function->{scope}"); |
| } |
| } |
| } |
| { package expr; # pick up expressioins |
| sub re { |
| my ($class, $line, $opcode) = @_; |
| my $self = {}; |
| my $ret; |
| |
| if ($$line =~ /(^[^,]+)/) { |
| bless $self,$class; |
| $self->{value} = $1; |
| $ret = $self; |
| $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; |
| |
| $self->{value} =~ s/\@PLT// if (!$elf); |
| $self->{value} =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei; |
| $self->{value} =~ s/\.L/$decor/g; |
| $self->{opcode} = $opcode; |
| } |
| $ret; |
| } |
| sub out { |
| my $self = shift; |
| if ($nasm && $self->{opcode}->mnemonic()=~m/^j(?![re]cxz)/) { |
| "NEAR ".$self->{value}; |
| } else { |
| $self->{value}; |
| } |
| } |
| } |
| { package directive; # pick up directives, which start with . |
| sub re { |
| my ($class, $line) = @_; |
| my $self = {}; |
| my $ret; |
| my $dir; |
| my %opcode = # lea 2f-1f(%rip),%dst; 1: nop; 2: |
| ( "%rax"=>0x01058d48, "%rcx"=>0x010d8d48, |
| "%rdx"=>0x01158d48, "%rbx"=>0x011d8d48, |
| "%rsp"=>0x01258d48, "%rbp"=>0x012d8d48, |
| "%rsi"=>0x01358d48, "%rdi"=>0x013d8d48, |
| "%r8" =>0x01058d4c, "%r9" =>0x010d8d4c, |
| "%r10"=>0x01158d4c, "%r11"=>0x011d8d4c, |
| "%r12"=>0x01258d4c, "%r13"=>0x012d8d4c, |
| "%r14"=>0x01358d4c, "%r15"=>0x013d8d4c ); |
| |
| if ($$line =~ /^\s*(\.\w+)/) { |
| bless $self,$class; |
| $dir = $1; |
| $ret = $self; |
| undef $self->{value}; |
| $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; |
| |
| SWITCH: for ($dir) { |
| /\.picmeup/ && do { if ($$line =~ /(%r[\w]+)/i) { |
| $dir="\t.long"; |
| $$line=sprintf "0x%x,0x90000000",$opcode{$1}; |
| } |
| last; |
| }; |
| /\.global|\.globl|\.extern/ |
| && do { $globals{$$line} = $prefix . $$line; |
| $$line = $globals{$$line} if ($prefix); |
| last; |
| }; |
| /\.type/ && do { my ($sym,$type,$narg) = split(',',$$line); |
| if ($type eq "\@function") { |
| undef $current_function; |
| $current_function->{name} = $sym; |
| $current_function->{abi} = "svr4"; |
| $current_function->{narg} = $narg; |
| $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE"; |
| } elsif ($type eq "\@abi-omnipotent") { |
| undef $current_function; |
| $current_function->{name} = $sym; |
| $current_function->{scope} = defined($globals{$sym})?"PUBLIC":"PRIVATE"; |
| } |
| $$line =~ s/\@abi\-omnipotent/\@function/; |
| $$line =~ s/\@function.*/\@function/; |
| last; |
| }; |
| /\.asciz/ && do { if ($$line =~ /^"(.*)"$/) { |
| $dir = ".byte"; |
| $$line = join(",",unpack("C*",$1),0); |
| } |
| last; |
| }; |
| /\.rva|\.long|\.quad/ |
| && do { $$line =~ s/([_a-z][_a-z0-9]*)/$globals{$1} or $1/gei; |
| $$line =~ s/\.L/$decor/g; |
| last; |
| }; |
| } |
| |
| if ($gas) { |
| $self->{value} = $dir . "\t" . $$line; |
| |
| if ($dir =~ /\.extern/) { |
| if ($flavour eq "elf") { |
| $self->{value} .= "\n.hidden $$line"; |
| } else { |
| $self->{value} = ""; |
| } |
| } elsif (!$elf && $dir =~ /\.type/) { |
| $self->{value} = ""; |
| $self->{value} = ".def\t" . ($globals{$1} or $1) . ";\t" . |
| (defined($globals{$1})?".scl 2;":".scl 3;") . |
| "\t.type 32;\t.endef" |
| if ($win64 && $$line =~ /([^,]+),\@function/); |
| } elsif (!$elf && $dir =~ /\.size/) { |
| $self->{value} = ""; |
| if (defined($current_function)) { |
| $self->{value} .= "${decor}SEH_end_$current_function->{name}:" |
| if ($win64 && $current_function->{abi} eq "svr4"); |
| undef $current_function; |
| } |
| } elsif (!$elf && $dir =~ /\.align/) { |
| $self->{value} = ".p2align\t" . (log($$line)/log(2)); |
| } elsif ($dir eq ".section") { |
| $current_segment=$$line; |
| if (!$elf && $current_segment eq ".init") { |
| if ($flavour eq "macosx") { $self->{value} = ".mod_init_func"; } |
| elsif ($flavour eq "mingw64") { $self->{value} = ".section\t.ctors"; } |
| } |
| } elsif ($dir =~ /\.(text|data)/) { |
| $current_segment=".$1"; |
| } elsif ($dir =~ /\.global|\.globl|\.extern/) { |
| if ($flavour eq "macosx") { |
| $self->{value} .= "\n.private_extern $$line"; |
| } else { |
| $self->{value} .= "\n.hidden $$line"; |
| } |
| } elsif ($dir =~ /\.hidden/) { |
| if ($flavour eq "macosx") { $self->{value} = ".private_extern\t$prefix$$line"; } |
| elsif ($flavour eq "mingw64") { $self->{value} = ""; } |
| } elsif ($dir =~ /\.comm/) { |
| $self->{value} = "$dir\t$prefix$$line"; |
| $self->{value} =~ s|,([0-9]+),([0-9]+)$|",$1,".log($2)/log(2)|e if ($flavour eq "macosx"); |
| } |
| $$line = ""; |
| return $self; |
| } |
| |
| # non-gas case or nasm/masm |
| SWITCH: for ($dir) { |
| /\.text/ && do { my $v=undef; |
| if ($nasm) { |
| $v="section .text code align=64\n"; |
| } else { |
| $v="$current_segment\tENDS\n" if ($current_segment); |
| $current_segment = ".text\$"; |
| $v.="$current_segment\tSEGMENT "; |
| $v.=$masm>=$masmref ? "ALIGN(256)" : "PAGE"; |
| $v.=" 'CODE'"; |
| } |
| $self->{value} = $v; |
| last; |
| }; |
| /\.data/ && do { my $v=undef; |
| if ($nasm) { |
| $v="section .data data align=8\n"; |
| } else { |
| $v="$current_segment\tENDS\n" if ($current_segment); |
| $current_segment = "_DATA"; |
| $v.="$current_segment\tSEGMENT"; |
| } |
| $self->{value} = $v; |
| last; |
| }; |
| /\.section/ && do { my $v=undef; |
| $$line =~ s/([^,]*).*/$1/; |
| $$line = ".CRT\$XCU" if ($$line eq ".init"); |
| if ($nasm) { |
| $v="section $$line"; |
| if ($$line=~/\.([px])data/) { |
| $v.=" rdata align="; |
| $v.=$1 eq "p"? 4 : 8; |
| } elsif ($$line=~/\.CRT\$/i) { |
| $v.=" rdata align=8"; |
| } |
| } else { |
| $v="$current_segment\tENDS\n" if ($current_segment); |
| $v.="$$line\tSEGMENT"; |
| if ($$line=~/\.([px])data/) { |
| $v.=" READONLY"; |
| $v.=" ALIGN(".($1 eq "p" ? 4 : 8).")" if ($masm>=$masmref); |
| } elsif ($$line=~/\.CRT\$/i) { |
| $v.=" READONLY "; |
| $v.=$masm>=$masmref ? "ALIGN(8)" : "DWORD"; |
| } |
| } |
| $current_segment = $$line; |
| $self->{value} = $v; |
| last; |
| }; |
| /\.extern/ && do { $self->{value} = "EXTERN\t".$$line; |
| $self->{value} .= ":NEAR" if ($masm); |
| last; |
| }; |
| /\.globl|.global/ |
| && do { $self->{value} = $masm?"PUBLIC":"global"; |
| $self->{value} .= "\t".$$line; |
| last; |
| }; |
| /\.size/ && do { if (defined($current_function)) { |
| undef $self->{value}; |
| if ($current_function->{abi} eq "svr4") { |
| $self->{value}="${decor}SEH_end_$current_function->{name}:"; |
| $self->{value}.=":\n" if($masm); |
| } |
| $self->{value}.="$current_function->{name}\tENDP" if($masm && $current_function->{name}); |
| undef $current_function; |
| } |
| last; |
| }; |
| /\.align/ && do { my $max = ($masm && $masm>=$masmref) ? 256 : 4096; |
| $self->{value} = "ALIGN\t".($$line>$max?$max:$$line); |
| last; |
| }; |
| /\.(value|long|rva|quad)/ |
| && do { my $sz = substr($1,0,1); |
| my @arr = split(/,\s*/,$$line); |
| my $last = pop(@arr); |
| my $conv = sub { my $var=shift; |
| $var=~s/^(0b[0-1]+)/oct($1)/eig; |
| $var=~s/^0x([0-9a-f]+)/0$1h/ig if ($masm); |
| if ($sz eq "D" && ($current_segment=~/.[px]data/ || $dir eq ".rva")) |
| { $var=~s/([_a-z\$\@][_a-z0-9\$\@]*)/$nasm?"$1 wrt ..imagebase":"imagerel $1"/egi; } |
| $var; |
| }; |
| |
| $sz =~ tr/bvlrq/BWDDQ/; |
| $self->{value} = "\tD$sz\t"; |
| for (@arr) { $self->{value} .= &$conv($_).","; } |
| $self->{value} .= &$conv($last); |
| last; |
| }; |
| /\.byte/ && do { my @str=split(/,\s*/,$$line); |
| map(s/(0b[0-1]+)/oct($1)/eig,@str); |
| map(s/0x([0-9a-f]+)/0$1h/ig,@str) if ($masm); |
| while ($#str>15) { |
| $self->{value}.="DB\t" |
| .join(",",@str[0..15])."\n"; |
| foreach (0..15) { shift @str; } |
| } |
| $self->{value}.="DB\t" |
| .join(",",@str) if (@str); |
| last; |
| }; |
| /\.comm/ && do { my @str=split(/,\s*/,$$line); |
| my $v=undef; |
| if ($nasm) { |
| $v.="common $prefix@str[0] @str[1]"; |
| } else { |
| $v="$current_segment\tENDS\n" if ($current_segment); |
| $current_segment = "_DATA"; |
| $v.="$current_segment\tSEGMENT\n"; |
| $v.="COMM @str[0]:DWORD:".@str[1]/4; |
| } |
| $self->{value} = $v; |
| last; |
| }; |
| } |
| $$line = ""; |
| } |
| |
| $ret; |
| } |
| sub out { |
| my $self = shift; |
| $self->{value}; |
| } |
| } |
| |
| sub rex { |
| my $opcode=shift; |
| my ($dst,$src,$rex)=@_; |
| |
| $rex|=0x04 if($dst>=8); |
| $rex|=0x01 if($src>=8); |
| push @$opcode,($rex|0x40) if ($rex); |
| } |
| |
| # Upon initial x86_64 introduction SSE>2 extensions were not introduced |
| # yet. In order not to be bothered by tracing exact assembler versions, |
| # but at the same time to provide a bare security minimum of AES-NI, we |
| # hard-code some instructions. Extensions past AES-NI on the other hand |
| # are traced by examining assembler version in individual perlasm |
| # modules... |
| |
| my %regrm = ( "%eax"=>0, "%ecx"=>1, "%edx"=>2, "%ebx"=>3, |
| "%esp"=>4, "%ebp"=>5, "%esi"=>6, "%edi"=>7 ); |
| |
| my $movq = sub { # elderly gas can't handle inter-register movq |
| my $arg = shift; |
| my @opcode=(0x66); |
| if ($arg =~ /%xmm([0-9]+),\s*%r(\w+)/) { |
| my ($src,$dst)=($1,$2); |
| if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; } |
| rex(\@opcode,$src,$dst,0x8); |
| push @opcode,0x0f,0x7e; |
| push @opcode,0xc0|(($src&7)<<3)|($dst&7); # ModR/M |
| @opcode; |
| } elsif ($arg =~ /%r(\w+),\s*%xmm([0-9]+)/) { |
| my ($src,$dst)=($2,$1); |
| if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; } |
| rex(\@opcode,$src,$dst,0x8); |
| push @opcode,0x0f,0x6e; |
| push @opcode,0xc0|(($src&7)<<3)|($dst&7); # ModR/M |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| my $pextrd = sub { |
| if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*(%\w+)/) { |
| my @opcode=(0x66); |
| my $imm=$1; |
| my $src=$2; |
| my $dst=$3; |
| if ($dst =~ /%r([0-9]+)d/) { $dst = $1; } |
| elsif ($dst =~ /%e/) { $dst = $regrm{$dst}; } |
| rex(\@opcode,$src,$dst); |
| push @opcode,0x0f,0x3a,0x16; |
| push @opcode,0xc0|(($src&7)<<3)|($dst&7); # ModR/M |
| push @opcode,$imm; |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| my $pinsrd = sub { |
| if (shift =~ /\$([0-9]+),\s*(%\w+),\s*%xmm([0-9]+)/) { |
| my @opcode=(0x66); |
| my $imm=$1; |
| my $src=$2; |
| my $dst=$3; |
| if ($src =~ /%r([0-9]+)/) { $src = $1; } |
| elsif ($src =~ /%e/) { $src = $regrm{$src}; } |
| rex(\@opcode,$dst,$src); |
| push @opcode,0x0f,0x3a,0x22; |
| push @opcode,0xc0|(($dst&7)<<3)|($src&7); # ModR/M |
| push @opcode,$imm; |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| my $pshufb = sub { |
| if (shift =~ /%xmm([0-9]+),\s*%xmm([0-9]+)/) { |
| my @opcode=(0x66); |
| rex(\@opcode,$2,$1); |
| push @opcode,0x0f,0x38,0x00; |
| push @opcode,0xc0|($1&7)|(($2&7)<<3); # ModR/M |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| my $palignr = sub { |
| if (shift =~ /\$([0-9]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) { |
| my @opcode=(0x66); |
| rex(\@opcode,$3,$2); |
| push @opcode,0x0f,0x3a,0x0f; |
| push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M |
| push @opcode,$1; |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| my $pclmulqdq = sub { |
| if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) { |
| my @opcode=(0x66); |
| rex(\@opcode,$3,$2); |
| push @opcode,0x0f,0x3a,0x44; |
| push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M |
| my $c=$1; |
| push @opcode,$c=~/^0/?oct($c):$c; |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| my $rdrand = sub { |
| if (shift =~ /%[er](\w+)/) { |
| my @opcode=(); |
| my $dst=$1; |
| if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; } |
| rex(\@opcode,0,$1,8); |
| push @opcode,0x0f,0xc7,0xf0|($dst&7); |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| my $rdseed = sub { |
| if (shift =~ /%[er](\w+)/) { |
| my @opcode=(); |
| my $dst=$1; |
| if ($dst !~ /[0-9]+/) { $dst = $regrm{"%e$dst"}; } |
| rex(\@opcode,0,$1,8); |
| push @opcode,0x0f,0xc7,0xf8|($dst&7); |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| sub rxb { |
| my $opcode=shift; |
| my ($dst,$src1,$src2,$rxb)=@_; |
| |
| $rxb|=0x7<<5; |
| $rxb&=~(0x04<<5) if($dst>=8); |
| $rxb&=~(0x01<<5) if($src1>=8); |
| $rxb&=~(0x02<<5) if($src2>=8); |
| push @$opcode,$rxb; |
| } |
| |
| my $vprotd = sub { |
| if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) { |
| my @opcode=(0x8f); |
| rxb(\@opcode,$3,$2,-1,0x08); |
| push @opcode,0x78,0xc2; |
| push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M |
| my $c=$1; |
| push @opcode,$c=~/^0/?oct($c):$c; |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| my $vprotq = sub { |
| if (shift =~ /\$([x0-9a-f]+),\s*%xmm([0-9]+),\s*%xmm([0-9]+)/) { |
| my @opcode=(0x8f); |
| rxb(\@opcode,$3,$2,-1,0x08); |
| push @opcode,0x78,0xc3; |
| push @opcode,0xc0|($2&7)|(($3&7)<<3); # ModR/M |
| my $c=$1; |
| push @opcode,$c=~/^0/?oct($c):$c; |
| @opcode; |
| } else { |
| (); |
| } |
| }; |
| |
| my $endbranch = sub { |
| (0xf3,0x0f,0x1e,0xfa); |
| }; |
| |
| if ($nasm) { |
| print <<___; |
| default rel |
| %define XMMWORD |
| %define YMMWORD |
| %define ZMMWORD |
| ___ |
| } elsif ($masm) { |
| print <<___; |
| OPTION DOTNAME |
| ___ |
| } |
| print STDOUT "#if defined(__x86_64__)\n" if ($gas); |
| |
| while(defined(my $line=<>)) { |
| |
| $line =~ s|\R$||; # Better chomp |
| |
| $line =~ s|[#!].*$||; # get rid of asm-style comments... |
| $line =~ s|/\*.*\*/||; # ... and C-style comments... |
| $line =~ s|^\s+||; # ... and skip white spaces in beginning |
| $line =~ s|\s+$||; # ... and at the end |
| |
| if (my $label=label->re(\$line)) { print $label->out(); } |
| |
| if (my $directive=directive->re(\$line)) { |
| printf "%s",$directive->out(); |
| } elsif (my $opcode=opcode->re(\$line)) { |
| my $asm = eval("\$".$opcode->mnemonic()); |
| |
| if ((ref($asm) eq 'CODE') && scalar(my @bytes=&$asm($line))) { |
| print $gas?".byte\t":"DB\t",join(',',@bytes),"\n"; |
| next; |
| } |
| |
| my @args; |
| ARGUMENT: while (1) { |
| my $arg; |
| |
| ($arg=register->re(\$line, $opcode))|| |
| ($arg=const->re(\$line)) || |
| ($arg=ea->re(\$line, $opcode)) || |
| ($arg=expr->re(\$line, $opcode)) || |
| last ARGUMENT; |
| |
| push @args,$arg; |
| |
| last ARGUMENT if ($line !~ /^,/); |
| |
| $line =~ s/^,\s*//; |
| } # ARGUMENT: |
| |
| if ($#args>=0) { |
| my $insn; |
| my $sz=$opcode->size(); |
| |
| if ($gas) { |
| $insn = $opcode->out($#args>=1?$args[$#args]->size():$sz); |
| @args = map($_->out($sz),@args); |
| printf "\t%s\t%s",$insn,join(",",@args); |
| } else { |
| $insn = $opcode->out(); |
| foreach (@args) { |
| my $arg = $_->out(); |
| # $insn.=$sz compensates for movq, pinsrw, ... |
| if ($arg =~ /^xmm[0-9]+$/) { $insn.=$sz; $sz="x" if(!$sz); last; } |
| if ($arg =~ /^ymm[0-9]+$/) { $insn.=$sz; $sz="y" if(!$sz); last; } |
| if ($arg =~ /^zmm[0-9]+$/) { $insn.=$sz; $sz="z" if(!$sz); last; } |
| if ($arg =~ /^mm[0-9]+$/) { $insn.=$sz; $sz="q" if(!$sz); last; } |
| } |
| @args = reverse(@args); |
| undef $sz if ($nasm && $opcode->mnemonic() eq "lea"); |
| |
| if ($insn eq "movq" && $#args == 1 && $args[0]->out($sz) eq "xmm0" && $args[1]->out($sz) eq "rax") { |
| # I have no clue why MASM can't parse this instruction. |
| printf "DB 66h, 48h, 0fh, 6eh, 0c0h"; |
| } else { |
| printf "\t%s\t%s",$insn,join(",",map($_->out($sz),@args)); |
| } |
| } |
| } else { |
| printf "\t%s",$opcode->out(); |
| } |
| } |
| |
| print $line,"\n"; |
| } |
| |
| print "\n$current_segment\tENDS\n" if ($current_segment && $masm); |
| print "END\n" if ($masm); |
| print "#endif\n" if ($gas); |
| |
| |
| close STDOUT; |
| |
| ################################################# |
| # Cross-reference x86_64 ABI "card" |
| # |
| # Unix Win64 |
| # %rax * * |
| # %rbx - - |
| # %rcx #4 #1 |
| # %rdx #3 #2 |
| # %rsi #2 - |
| # %rdi #1 - |
| # %rbp - - |
| # %rsp - - |
| # %r8 #5 #3 |
| # %r9 #6 #4 |
| # %r10 * * |
| # %r11 * * |
| # %r12 - - |
| # %r13 - - |
| # %r14 - - |
| # %r15 - - |
| # |
| # (*) volatile register |
| # (-) preserved by callee |
| # (#) Nth argument, volatile |
| # |
| # In Unix terms top of stack is argument transfer area for arguments |
| # which could not be accommodated in registers. Or in other words 7th |
| # [integer] argument resides at 8(%rsp) upon function entry point. |
| # 128 bytes above %rsp constitute a "red zone" which is not touched |
| # by signal handlers and can be used as temporal storage without |
| # allocating a frame. |
| # |
| # In Win64 terms N*8 bytes on top of stack is argument transfer area, |
| # which belongs to/can be overwritten by callee. N is the number of |
| # arguments passed to callee, *but* not less than 4! This means that |
| # upon function entry point 5th argument resides at 40(%rsp), as well |
| # as that 32 bytes from 8(%rsp) can always be used as temporal |
| # storage [without allocating a frame]. One can actually argue that |
| # one can assume a "red zone" above stack pointer under Win64 as well. |
| # Point is that at apparently no occasion Windows kernel would alter |
| # the area above user stack pointer in true asynchronous manner... |
| # |
| # All the above means that if assembler programmer adheres to Unix |
| # register and stack layout, but disregards the "red zone" existense, |
| # it's possible to use following prologue and epilogue to "gear" from |
| # Unix to Win64 ABI in leaf functions with not more than 6 arguments. |
| # |
| # omnipotent_function: |
| # ifdef WIN64 |
| # movq %rdi,8(%rsp) |
| # movq %rsi,16(%rsp) |
| # movq %rcx,%rdi ; if 1st argument is actually present |
| # movq %rdx,%rsi ; if 2nd argument is actually ... |
| # movq %r8,%rdx ; if 3rd argument is ... |
| # movq %r9,%rcx ; if 4th argument ... |
| # movq 40(%rsp),%r8 ; if 5th ... |
| # movq 48(%rsp),%r9 ; if 6th ... |
| # endif |
| # ... |
| # ifdef WIN64 |
| # movq 8(%rsp),%rdi |
| # movq 16(%rsp),%rsi |
| # endif |
| # ret |
| # |
| ################################################# |
| # Win64 SEH, Structured Exception Handling. |
| # |
| # Unlike on Unix systems(*) lack of Win64 stack unwinding information |
| # has undesired side-effect at run-time: if an exception is raised in |
| # assembler subroutine such as those in question (basically we're |
| # referring to segmentation violations caused by malformed input |
| # parameters), the application is briskly terminated without invoking |
| # any exception handlers, most notably without generating memory dump |
| # or any user notification whatsoever. This poses a problem. It's |
| # possible to address it by registering custom language-specific |
| # handler that would restore processor context to the state at |
| # subroutine entry point and return "exception is not handled, keep |
| # unwinding" code. Writing such handler can be a challenge... But it's |
| # doable, though requires certain coding convention. Consider following |
| # snippet: |
| # |
| # .type function,@function |
| # function: |
| # movq %rsp,%rax # copy rsp to volatile register |
| # pushq %r15 # save non-volatile registers |
| # pushq %rbx |
| # pushq %rbp |
| # movq %rsp,%r11 |
| # subq %rdi,%r11 # prepare [variable] stack frame |
| # andq $-64,%r11 |
| # movq %rax,0(%r11) # check for exceptions |
| # movq %r11,%rsp # allocate [variable] stack frame |
| # movq %rax,0(%rsp) # save original rsp value |
| # magic_point: |
| # ... |
| # movq 0(%rsp),%rcx # pull original rsp value |
| # movq -24(%rcx),%rbp # restore non-volatile registers |
| # movq -16(%rcx),%rbx |
| # movq -8(%rcx),%r15 |
| # movq %rcx,%rsp # restore original rsp |
| # ret |
| # .size function,.-function |
| # |
| # The key is that up to magic_point copy of original rsp value remains |
| # in chosen volatile register and no non-volatile register, except for |
| # rsp, is modified. While past magic_point rsp remains constant till |
| # the very end of the function. In this case custom language-specific |
| # exception handler would look like this: |
| # |
| # EXCEPTION_DISPOSITION handler (EXCEPTION_RECORD *rec,ULONG64 frame, |
| # CONTEXT *context,DISPATCHER_CONTEXT *disp) |
| # { ULONG64 *rsp = (ULONG64 *)context->Rax; |
| # if (context->Rip >= magic_point) |
| # { rsp = ((ULONG64 **)context->Rsp)[0]; |
| # context->Rbp = rsp[-3]; |
| # context->Rbx = rsp[-2]; |
| # context->R15 = rsp[-1]; |
| # } |
| # context->Rsp = (ULONG64)rsp; |
| # context->Rdi = rsp[1]; |
| # context->Rsi = rsp[2]; |
| # |
| # memcpy (disp->ContextRecord,context,sizeof(CONTEXT)); |
| # RtlVirtualUnwind(UNW_FLAG_NHANDLER,disp->ImageBase, |
| # dips->ControlPc,disp->FunctionEntry,disp->ContextRecord, |
| # &disp->HandlerData,&disp->EstablisherFrame,NULL); |
| # return ExceptionContinueSearch; |
| # } |
| # |
| # It's appropriate to implement this handler in assembler, directly in |
| # function's module. In order to do that one has to know members' |
| # offsets in CONTEXT and DISPATCHER_CONTEXT structures and some constant |
| # values. Here they are: |
| # |
| # CONTEXT.Rax 120 |
| # CONTEXT.Rcx 128 |
| # CONTEXT.Rdx 136 |
| # CONTEXT.Rbx 144 |
| # CONTEXT.Rsp 152 |
| # CONTEXT.Rbp 160 |
| # CONTEXT.Rsi 168 |
| # CONTEXT.Rdi 176 |
| # CONTEXT.R8 184 |
| # CONTEXT.R9 192 |
| # CONTEXT.R10 200 |
| # CONTEXT.R11 208 |
| # CONTEXT.R12 216 |
| # CONTEXT.R13 224 |
| # CONTEXT.R14 232 |
| # CONTEXT.R15 240 |
| # CONTEXT.Rip 248 |
| # CONTEXT.Xmm6 512 |
| # sizeof(CONTEXT) 1232 |
| # DISPATCHER_CONTEXT.ControlPc 0 |
| # DISPATCHER_CONTEXT.ImageBase 8 |
| # DISPATCHER_CONTEXT.FunctionEntry 16 |
| # DISPATCHER_CONTEXT.EstablisherFrame 24 |
| # DISPATCHER_CONTEXT.TargetIp 32 |
| # DISPATCHER_CONTEXT.ContextRecord 40 |
| # DISPATCHER_CONTEXT.LanguageHandler 48 |
| # DISPATCHER_CONTEXT.HandlerData 56 |
| # UNW_FLAG_NHANDLER 0 |
| # ExceptionContinueSearch 1 |
| # |
| # In order to tie the handler to the function one has to compose |
| # couple of structures: one for .xdata segment and one for .pdata. |
| # |
| # UNWIND_INFO structure for .xdata segment would be |
| # |
| # function_unwind_info: |
| # .byte 9,0,0,0 |
| # .rva handler |
| # |
| # This structure designates exception handler for a function with |
| # zero-length prologue, no stack frame or frame register. |
| # |
| # To facilitate composing of .pdata structures, auto-generated "gear" |
| # prologue copies rsp value to rax and denotes next instruction with |
| # .LSEH_begin_{function_name} label. This essentially defines the SEH |
| # styling rule mentioned in the beginning. Position of this label is |
| # chosen in such manner that possible exceptions raised in the "gear" |
| # prologue would be accounted to caller and unwound from latter's frame. |
| # End of function is marked with respective .LSEH_end_{function_name} |
| # label. To summarize, .pdata segment would contain |
| # |
| # .rva .LSEH_begin_function |
| # .rva .LSEH_end_function |
| # .rva function_unwind_info |
| # |
| # Reference to function_unwind_info from .xdata segment is the anchor. |
| # In case you wonder why references are 32-bit .rvas and not 64-bit |
| # .quads. References put into these two segments are required to be |
| # *relative* to the base address of the current binary module, a.k.a. |
| # image base. No Win64 module, be it .exe or .dll, can be larger than |
| # 2GB and thus such relative references can be and are accommodated in |
| # 32 bits. |
| # |
| # Having reviewed the example function code, one can argue that "movq |
| # %rsp,%rax" above is redundant. It is not! Keep in mind that on Unix |
| # rax would contain an undefined value. If this "offends" you, use |
| # another register and refrain from modifying rax till magic_point is |
| # reached, i.e. as if it was a non-volatile register. If more registers |
| # are required prior [variable] frame setup is completed, note that |
| # nobody says that you can have only one "magic point." You can |
| # "liberate" non-volatile registers by denoting last stack off-load |
| # instruction and reflecting it in finer grade unwind logic in handler. |
| # After all, isn't it why it's called *language-specific* handler... |
| # |
| # Attentive reader can notice that exceptions would be mishandled in |
| # auto-generated "gear" epilogue. Well, exception effectively can't |
| # occur there, because if memory area used by it was subject to |
| # segmentation violation, then it would be raised upon call to the |
| # function (and as already mentioned be accounted to caller, which is |
| # not a problem). If you're still not comfortable, then define tail |
| # "magic point" just prior ret instruction and have handler treat it... |
| # |
| # (*) Note that we're talking about run-time, not debug-time. Lack of |
| # unwind information makes debugging hard on both Windows and |
| # Unix. "Unlike" referes to the fact that on Unix signal handler |
| # will always be invoked, core dumped and appropriate exit code |
| # returned to parent (for user notification). |