diff options
Diffstat (limited to 'src/crypto/zinc/perlasm/x86_64-xlate.pl')
| -rw-r--r-- | src/crypto/zinc/perlasm/x86_64-xlate.pl | 1432 |
1 files changed, 1432 insertions, 0 deletions
diff --git a/src/crypto/zinc/perlasm/x86_64-xlate.pl b/src/crypto/zinc/perlasm/x86_64-xlate.pl new file mode 100644 index 0000000..f8380f2 --- /dev/null +++ b/src/crypto/zinc/perlasm/x86_64-xlate.pl @@ -0,0 +1,1432 @@ +#! /usr/bin/env perl +# Copyright 2005-2018 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. +# +# 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; + $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) +{ if ($ENV{ASM} =~ m/nasm/ && `nasm -v` =~ m/version ([0-9]+)\.([0-9]+)/i) + { $nasm = $1 + $2*0.01; $PTR=""; } + elsif (`ml64 2>&1` =~ m/Version ([0-9]+)\.([0-9]+)(\.([0-9]+))?/) + { $masm = $1 + $2*2**-16 + $4*2**-32; } + die "no assembler found on %PATH%" if (!($nasm || $masm)); + $win64=1; + $elf=0; + $decor="\$L\$"; +} + +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} =~ /^[vk]/) { # VEX or k* such as kmov + $self->{sz} = ""; + } elsif ($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 { + my $value = $self->{value}; + $value =~ s/0x([0-9a-f]+)/0$1h/ig if ($masm); + sprintf "%s",$value; + } + } +} +{ package ea; # pick up effective addresses: expr(%reg,%reg,scale) + + my %szmap = ( b=>"BYTE$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" ) if (!$gas); + + sub re { + my ($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})); + $self->{opmask} = $4; + $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 base register is %rbp or %r13, see if it's possible to + # flip base and index registers [for better performance] + 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)%s", + $self->{asterisk},$self->{label}, + $self->{base}?"%$self->{base}":"", + $self->{index},$self->{scale}, + $self->{opmask}; + } else { + sprintf "%s%s(%%%s)%s", $self->{asterisk},$self->{label}, + $self->{base},$self->{opmask}; + } + } else { + $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"); + + $self->{opmask} =~ s/%(k[0-7])/$1/; + + if (defined($self->{index})) { + sprintf "%s[%s%s*%d%s]%s",$szmap{$sz}, + $self->{label}?"$self->{label}+":"", + $self->{index},$self->{scale}, + $self->{base}?"+$self->{base}":"", + $self->{opmask}; + } elsif ($self->{base} eq "rip") { + sprintf "%s[%s]",$szmap{$sz},$self->{label}; + } else { + sprintf "%s[%s%s]%s", $szmap{$sz}, + $self->{label}?"$self->{label}+":"", + $self->{base},$self->{opmask}; + } + } + } +} +{ 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; + $self->{opmask} = $3; + $opcode->size($self->size()); + $ret = $self; + $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; + } + $ret; + } + sub size { + my $self = shift; + my $ret; + + if ($self->{value} =~ /^r[\d]+b$/i) { $ret="b"; } + elsif ($self->{value} =~ /^r[\d]+w$/i) { $ret="w"; } + elsif ($self->{value} =~ /^r[\d]+d$/i) { $ret="l"; } + elsif ($self->{value} =~ /^r[\w]+$/i) { $ret="q"; } + elsif ($self->{value} =~ /^[a-d][hl]$/i){ $ret="b"; } + elsif ($self->{value} =~ /^[\w]{2}l$/i) { $ret="b"; } + elsif ($self->{value} =~ /^[\w]{2}$/i) { $ret="w"; } + elsif ($self->{value} =~ /^e[a-z]{2}$/i){ $ret="l"; } + + $ret; + } + sub out { + my $self = shift; + if ($gas) { sprintf "%s%%%s%s", $self->{asterisk}, + $self->{value}, + $self->{opmask}; } + else { $self->{opmask} =~ s/%(k[0-7])/$1/; + $self->{value}.$self->{opmask}; } + } +} +{ package label; # pick up labels, which end with : + sub re { + my ($class, $line) = @_; + my $self = {}; + my $ret; + + if ($$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 $current_function->{scope}"); + } + } +} +{ package expr; # pick up expressions + sub re { + my ($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 cfi_directive; + # CFI directives annotate instructions that are significant for + # stack unwinding procedure compliant with DWARF specification, + # see http://dwarfstd.org/. Besides naturally expected for this + # script platform-specific filtering function, this module adds + # three auxiliary synthetic directives not recognized by [GNU] + # assembler: + # + # - .cfi_push to annotate push instructions in prologue, which + # translates to .cfi_adjust_cfa_offset (if needed) and + # .cfi_offset; + # - .cfi_pop to annotate pop instructions in epilogue, which + # translates to .cfi_adjust_cfa_offset (if needed) and + # .cfi_restore; + # - [and most notably] .cfi_cfa_expression which encodes + # DW_CFA_def_cfa_expression and passes it to .cfi_escape as + # byte vector; + # + # CFA expressions were introduced in DWARF specification version + # 3 and describe how to deduce CFA, Canonical Frame Address. This + # becomes handy if your stack frame is variable and you can't + # spare register for [previous] frame pointer. Suggested directive + # syntax is made-up mix of DWARF operator suffixes [subset of] + # and references to registers with optional bias. Following example + # describes offloaded *original* stack pointer at specific offset + # from *current* stack pointer: + # + # .cfi_cfa_expression %rsp+40,deref,+8 + # + # Final +8 has everything to do with the fact that CFA is defined + # as reference to top of caller's stack, and on x86_64 call to + # subroutine pushes 8-byte return address. In other words original + # stack pointer upon entry to a subroutine is 8 bytes off from CFA. + + # Below constants are taken from "DWARF Expressions" section of the + # DWARF specification, section is numbered 7.7 in versions 3 and 4. + my %DW_OP_simple = ( # no-arg operators, mapped directly + deref => 0x06, dup => 0x12, + drop => 0x13, over => 0x14, + pick => 0x15, swap => 0x16, + rot => 0x17, xderef => 0x18, + + abs => 0x19, and => 0x1a, + div => 0x1b, minus => 0x1c, + mod => 0x1d, mul => 0x1e, + neg => 0x1f, not => 0x20, + or => 0x21, plus => 0x22, + shl => 0x24, shr => 0x25, + shra => 0x26, xor => 0x27, + ); + + my %DW_OP_complex = ( # used in specific subroutines + constu => 0x10, # uleb128 + consts => 0x11, # sleb128 + plus_uconst => 0x23, # uleb128 + lit0 => 0x30, # add 0-31 to opcode + reg0 => 0x50, # add 0-31 to opcode + breg0 => 0x70, # add 0-31 to opcole, sleb128 + regx => 0x90, # uleb28 + fbreg => 0x91, # sleb128 + bregx => 0x92, # uleb128, sleb128 + piece => 0x93, # uleb128 + ); + + # Following constants are defined in x86_64 ABI supplement, for + # example available at https://www.uclibc.org/docs/psABI-x86_64.pdf, + # see section 3.7 "Stack Unwind Algorithm". + my %DW_reg_idx = ( + "%rax"=>0, "%rdx"=>1, "%rcx"=>2, "%rbx"=>3, + "%rsi"=>4, "%rdi"=>5, "%rbp"=>6, "%rsp"=>7, + "%r8" =>8, "%r9" =>9, "%r10"=>10, "%r11"=>11, + "%r12"=>12, "%r13"=>13, "%r14"=>14, "%r15"=>15 + ); + + my ($cfa_reg, $cfa_rsp); + + # [us]leb128 format is variable-length integer representation base + # 2^128, with most significant bit of each byte being 0 denoting + # *last* most significant digit. See "Variable Length Data" in the + # DWARF specification, numbered 7.6 at least in versions 3 and 4. + sub sleb128 { + use integer; # get right shift extend sign + + my $val = shift; + my $sign = ($val < 0) ? -1 : 0; + my @ret = (); + + while(1) { + push @ret, $val&0x7f; + + # see if remaining bits are same and equal to most + # significant bit of the current digit, if so, it's + # last digit... + last if (($val>>6) == $sign); + + @ret[-1] |= 0x80; + $val >>= 7; + } + + return @ret; + } + sub uleb128 { + my $val = shift; + my @ret = (); + + while(1) { + push @ret, $val&0x7f; + + # see if it's last significant digit... + last if (($val >>= 7) == 0); + + @ret[-1] |= 0x80; + } + + return @ret; + } + sub const { + my $val = shift; + + if ($val >= 0 && $val < 32) { + return ($DW_OP_complex{lit0}+$val); + } + return ($DW_OP_complex{consts}, sleb128($val)); + } + sub reg { + my $val = shift; + + return if ($val !~ m/^(%r\w+)(?:([\+\-])((?:0x)?[0-9a-f]+))?/); + + my $reg = $DW_reg_idx{$1}; + my $off = eval ("0 $2 $3"); + + return (($DW_OP_complex{breg0} + $reg), sleb128($off)); + # Yes, we use DW_OP_bregX+0 to push register value and not + # DW_OP_regX, because latter would require even DW_OP_piece, + # which would be a waste under the circumstances. If you have + # to use DWP_OP_reg, use "regx:N"... + } + sub cfa_expression { + my $line = shift; + my @ret; + + foreach my $token (split(/,\s*/,$line)) { + if ($token =~ /^%r/) { + push @ret,reg($token); + } elsif ($token =~ /((?:0x)?[0-9a-f]+)\((%r\w+)\)/) { + push @ret,reg("$2+$1"); + } elsif ($token =~ /(\w+):(\-?(?:0x)?[0-9a-f]+)(U?)/i) { + my $i = 1*eval($2); + push @ret,$DW_OP_complex{$1}, ($3 ? uleb128($i) : sleb128($i)); + } elsif (my $i = 1*eval($token) or $token eq "0") { + if ($token =~ /^\+/) { + push @ret,$DW_OP_complex{plus_uconst},uleb128($i); + } else { + push @ret,const($i); + } + } else { + push @ret,$DW_OP_simple{$token}; + } + } + + # Finally we return DW_CFA_def_cfa_expression, 15, followed by + # length of the expression and of course the expression itself. + return (15,scalar(@ret),@ret); + } + sub re { + my ($class, $line) = @_; + my $self = {}; + my $ret; + + if ($$line =~ s/^\s*\.cfi_(\w+)\s*//) { + bless $self,$class; + $ret = $self; + undef $self->{value}; + my $dir = $1; + + SWITCH: for ($dir) { + # What is $cfa_rsp? Effectively it's difference between %rsp + # value and current CFA, Canonical Frame Address, which is + # why it starts with -8. Recall that CFA is top of caller's + # stack... + /startproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", -8); last; }; + /endproc/ && do { ($cfa_reg, $cfa_rsp) = ("%rsp", 0); last; }; + /def_cfa_register/ + && do { $cfa_reg = $$line; last; }; + /def_cfa_offset/ + && do { $cfa_rsp = -1*eval($$line) if ($cfa_reg eq "%rsp"); + last; + }; + /adjust_cfa_offset/ + && do { $cfa_rsp -= 1*eval($$line) if ($cfa_reg eq "%rsp"); + last; + }; + /def_cfa/ && do { if ($$line =~ /(%r\w+)\s*,\s*(.+)/) { + $cfa_reg = $1; + $cfa_rsp = -1*eval($2) if ($cfa_reg eq "%rsp"); + } + last; + }; + /push/ && do { $dir = undef; + $cfa_rsp -= 8; + if ($cfa_reg eq "%rsp") { + $self->{value} = ".cfi_adjust_cfa_offset\t8\n"; + } + $self->{value} .= ".cfi_offset\t$$line,$cfa_rsp"; + last; + }; + /pop/ && do { $dir = undef; + $cfa_rsp += 8; + if ($cfa_reg eq "%rsp") { + $self->{value} = ".cfi_adjust_cfa_offset\t-8\n"; + } + $self->{value} .= ".cfi_restore\t$$line"; + last; + }; + /cfa_expression/ + && do { $dir = undef; + $self->{value} = ".cfi_escape\t" . + join(",", map(sprintf("0x%02x", $_), + cfa_expression($$line))); + last; + }; + } + + $self->{value} = ".cfi_$dir\t$$line" if ($dir); + + $$line = ""; + } + + return $ret; + } + sub out { + my $self = shift; + return ($elf ? $self->{value} : undef); + } +} +{ package directive; # pick up directives, which start with . + sub re { + my ($class, $line) = @_; + my $self = {}; + my $ret; + my $dir; + + # chain-call to cfi_directive + $ret = cfi_directive->re($line) and return $ret; + + if ($$line =~ /^\s*(\.\w+)/) { + bless $self,$class; + $dir = $1; + $ret = $self; + undef $self->{value}; + $$line = substr($$line,@+[0]); $$line =~ s/^\s+//; + + SWITCH: for ($dir) { + /\.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/) { + $self->{value} = ""; # swallow extern + } elsif (!$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=$$line; + if (!$elf && $current_segment eq ".init") { + if ($flavour eq "macosx") { $self->{value} = ".mod_init_func"; } + elsif ($flavour eq "mingw64") { $self->{value} = ".section\t.ctors"; } + } + } elsif ($dir =~ /\.(text|data)/) { + $current_segment=".$1"; + } elsif ($dir =~ /\.hidden/) { + if ($flavour eq "macosx") { $self->{value} = ".private_extern\t$prefix$$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}; + } +} + +# 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 ); + +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); +} + +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,$dst,8); + push @opcode,0x0f,0xc7,0xf0|($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,$dst,8); + push @opcode,0x0f,0xc7,0xf8|($dst&7); + @opcode; + } else { + (); + } +}; + +# Not all AVX-capable assemblers recognize AMD XOP extension. Since we +# are using only two instructions hand-code them in order to be excused +# from chasing assembler versions... + +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 { + (); + } +}; + +# Intel Control-flow Enforcement Technology extension. All functions and +# indirect branch targets will have to start with this instruction... + +my $endbranch = sub { + (0xf3,0x0f,0x1e,0xfa); +}; + +######################################################################## + +if ($nasm) { + print <<___; +default rel +%define XMMWORD +%define YMMWORD +%define ZMMWORD +___ +} elsif ($masm) { + print <<___; +OPTION DOTNAME +___ +} +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 && $opcode->mnemonic() eq "lea"); + printf "\t%s\t%s",$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); + +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" existence, +# 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 +# magic_epilogue: +# 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; +# ULONG64 rip = context->Rip; +# +# if (rip >= magic_point) +# { rsp = (ULONG64 *)context->Rsp; +# if (rip < magic_epilogue) +# { rsp = (ULONG64 *)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... +# +# SE handlers are also involved in unwinding stack when executable is +# profiled or debugged. Profiling implies additional limitations that +# are too subtle to discuss here. For now it's sufficient to say that +# in order to simplify handlers one should either a) offload original +# %rsp to stack (like discussed above); or b) if you have a register to +# spare for frame pointer, choose volatile one. +# +# (*) Note that we're talking about run-time, not debug-time. Lack of +# unwind information makes debugging hard on both Windows and +# Unix. "Unlike" refers to the fact that on Unix signal handler +# will always be invoked, core dumped and appropriate exit code +# returned to parent (for user notification). |