The module risugen_x86_constraints.pm provides environment for evaluating x86 "!constraints" blocks. This is facilitated by the single exported function eval_constraints_block.
Signed-off-by: Jan Bobek <jan.bo...@gmail.com> --- risugen_x86_constraints.pm | 154 +++++++++++++++++++++++++++++++++++++ 1 file changed, 154 insertions(+) create mode 100644 risugen_x86_constraints.pm diff --git a/risugen_x86_constraints.pm b/risugen_x86_constraints.pm new file mode 100644 index 0000000..a4ee687 --- /dev/null +++ b/risugen_x86_constraints.pm @@ -0,0 +1,154 @@ +#!/usr/bin/perl -w +############################################################################### +# Copyright (c) 2019 Jan Bobek +# All rights reserved. This program and the accompanying materials +# are made available under the terms of the Eclipse Public License v1.0 +# which accompanies this distribution, and is available at +# http://www.eclipse.org/legal/epl-v10.html +# +# Contributors: +# Jan Bobek - initial implementation +############################################################################### + +# risugen_x86_constraints -- risugen_x86's helper module for "!constraints" blocks +package risugen_x86_constraints; + +use strict; +use warnings; + +use risugen_common; +use risugen_x86_asm; + +our @ISA = qw(Exporter); +our @EXPORT = qw(eval_constraints_block); + +my $is_x86_64; + +sub data16($%) +{ + my ($insn, %data16) = @_; + $insn->{data16} = \%data16; +} + +sub rep($%) +{ + my ($insn, %rep) = @_; + $insn->{rep} = \%rep; +} + +sub repne($%) +{ + my ($insn, %repne) = @_; + $insn->{repne} = \%repne; +} + +sub rex($%) +{ + my ($insn, %rex) = @_; + # It doesn't make sense to randomize any REX fields, since REX.W + # is opcode-like and REX.R/.X/.B are encoded automatically by + # risugen_x86_asm. + $insn->{rex} = \%rex; +} + +sub vex($%) +{ + my ($insn, %vex) = @_; + my $regidw = $is_x86_64 ? 4 : 3; + + # There is no point in randomizing other VEX fields, since + # VEX.R/.X/.B are encoded automatically by risugen_x86_asm, and + # VEX.M/.P are opcodes. + $vex{l} = randint(width => 1) ? 256 : 128 unless defined $vex{l}; + $vex{v} = randint(width => $regidw) unless defined $vex{v}; + $vex{w} = randint(width => 1) unless defined $vex{w}; + $insn->{vex} = \%vex; +} + +sub modrm_($%) +{ + my ($insn, %args) = @_; + my $regidw = $is_x86_64 ? 4 : 3; + + my %modrm = (); + if (defined $args{reg}) { + # This makes the config file syntax a bit more accommodating + # in cases where MODRM.REG is an opcode extension field. + $modrm{reg} = $args{reg}; + } else { + $modrm{reg} = randint(width => $regidw); + } + + # There is also a displacement-only form, but we don't know + # absolute address of the memblock, so we cannot test it. + my $form = int(rand(4)); + if ($form == 0) { + $modrm{reg2} = randint(width => $regidw); + } else { + $modrm{base} = randint(width => $regidw); + + if ($form == 2) { + $modrm{base} = randint(width => $regidw); + $modrm{disp}{value} = randint(width => 8, signed => 1); + $modrm{disp}{width} = 8; + } elsif ($form == 3) { + $modrm{base} = randint(width => $regidw); + $modrm{disp}{value} = randint(width => 32, signed => 1); + $modrm{disp}{width} = 32; + } + + my $have_index = int(rand(2)); + if ($have_index) { + my $indexk = $args{indexk}; + $modrm{ss} = randint(width => 2); + $modrm{$indexk} = randint(width => $regidw); + } + } + + $insn->{modrm} = \%modrm; +} + +sub modrm($%) +{ + my ($insn, %args) = @_; + modrm_($insn, indexk => 'index', %args); +} + +sub modrm_vsib($%) +{ + my ($insn, %args) = @_; + modrm_($insn, indexk => 'vindex', %args); +} + +sub imm($%) +{ + my ($insn, %args) = @_; + $insn->{imm}{value} = randint(%args); + $insn->{imm}{width} = $args{width}; +} + +sub eval_constraints_block(%) +{ + my (%args) = @_; + my $rec = $args{rec}; + my $insn = $args{insn}; + my $insnname = $rec->{name}; + my $opcode = $insn->{opcode}{value}; + + $is_x86_64 = $args{is_x86_64}; + + my $constraint = $rec->{blocks}{"constraints"}; + if (defined $constraint) { + # user-specified constraint: evaluate in an environment + # with variables set corresponding to the variable fields. + my %env = extract_fields($opcode, $rec); + # set the variable $_ to the instruction in question + $env{_} = $insn; + + return eval_block($insnname, "constraints", $constraint, \%env); + } else { + return 1; + } +} + +1; -- 2.20.1
