174 lines
5.8 KiB
Perl
174 lines
5.8 KiB
Perl
#! /usr/bin/perl
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# Copyright 2000, 2001 Free Software Foundation, Inc.
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#
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# This file is part of the GNU MP Library.
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#
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# The GNU MP Library is free software; you can redistribute it and/or modify
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# it under the terms of the GNU Lesser General Public License as published
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# by the Free Software Foundation; either version 2.1 of the License, or (at
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# your option) any later version.
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#
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# The GNU MP Library is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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# License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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# the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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# MA 02110-1301, USA.
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# Usage: cross.pl [filename.o]...
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#
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# Produce an annotated disassembly of the given object files, indicating
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# certain code alignment and addressing mode problems afflicting K6 chips.
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# "ZZ" is used on all annotations, so this can be searched for.
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#
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# With no arguments, all .o files corresponding to .asm files are processed.
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# This is good in the mpn object directory of a k6*-*-* build.
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#
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# Code alignments of 8 bytes or more are handled. When 32 is used, cache
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# line boundaries will fall in at offsets 0x20,0x40,etc and problems are
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# flagged at those locations. When 16 is used, the line boundaries can also
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# fall at offsets 0x10,0x30,0x50,etc, depending where the file is loaded, so
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# problems are identified there too. Likewise when 8 byte alignment is used
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# problems are flagged additionally at 0x08,0x18,0x28,etc.
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#
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# Usually 32 byte alignment is used for k6 routines, but less is certainly
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# possible if through good luck, or a little tweaking, cache line crossing
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# problems can be avoided at the extra locations.
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#
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# Bugs:
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#
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# Instructions without mod/rm bytes or which are already vector decoded are
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# unaffected by cache line boundary crossing, but not all of these have yet
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# been put in as exceptions. All that occur in practice in GMP are present
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# though.
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#
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# There's no messages for using the vector decoded addressing mode (%esi),
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# but that's easy to avoid when coding.
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#
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# Future:
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#
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# Warn about jump targets that are poorly aligned (less than 2 instructions
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# before a cache line boundary).
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use strict;
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sub disassemble {
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my ($file) = @_;
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my ($addr,$b1,$b2,$b3, $prefix,$opcode,$modrm);
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my $align;
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open (IN, "objdump -Srfh $file |")
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|| die "Cannot open pipe from objdump\n";
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while (<IN>) {
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print;
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if (/^[ \t]*[0-9]+[ \t]+\.text[ \t]/ && /2\*\*([0-9]+)$/) {
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$align = 1 << $1;
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if ($align < 8) {
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print "ZZ cross.pl cannot handle alignment < 2**3\n";
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$align = 8
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}
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}
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if (/^[ \t]*([0-9a-f]*):[ \t]*([0-9a-f]+)[ \t]+([0-9a-f]+)[ \t]+([0-9a-f]+)/) {
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($addr,$b1,$b2,$b3) = ($1,$2,$3,$4);
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} elsif (/^[ \t]*([0-9a-f]*):[ \t]*([0-9a-f]+)[ \t]+([0-9a-f]+)/) {
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($addr,$b1,$b2,$b3) = ($1,$2,$3,'');
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} elsif (/^[ \t]*([0-9a-f]*):[ \t]*([0-9a-f]+)/) {
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($addr,$b1,$b2,$b3) = ($1,$2,'','');
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} else {
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next;
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}
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if ($b1 =~ /0f/) {
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$prefix = $b1;
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$opcode = $b2;
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$modrm = $b3;
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} else {
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$prefix = '';
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$opcode = $b1;
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$modrm = $b2;
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}
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# modrm of the form 00-xxx-100 with an 0F prefix is the problem case
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# for K6 and pre-CXT K6-2
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if ($prefix =~ /0f/
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&& $opcode !~ /^8/ # jcond disp32
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&& $modrm =~ /^[0-3][4c]/) {
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print "ZZ ($file) >3 bytes to determine instruction length [K6]\n";
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}
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# with just an opcode, starting 1f mod 20h
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if (($align==32 && $addr =~ /[13579bdf]f$/
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|| $align==16 && $addr =~ /f$/
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|| $align==8 && $addr =~ /[7f]$/)
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&& $prefix !~ /0f/
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&& $opcode !~ /1[012345]/ # adc
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&& $opcode !~ /1[89abcd]/ # sbb
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&& $opcode !~ /^4/ # inc/dec reg
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&& $opcode !~ /^5/ # push/pop reg
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&& $opcode !~ /68/ # push $imm32
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&& $opcode !~ /^7/ # jcond disp8
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&& $opcode !~ /a[89]/ # test+imm
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&& $opcode !~ /a[a-f]/ # stos/lods/scas
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&& $opcode !~ /b8/ # movl $imm32,%eax
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&& $opcode !~ /d[0123]/ # rcl
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&& $opcode !~ /e[0123]/ # loop/loopz/loopnz/jcxz
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&& $opcode !~ /e8/ # call disp32
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&& $opcode !~ /e[9b]/ # jmp disp32/disp8
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&& $opcode !~ /f[89abcd]/ # clc,stc,cli,sti,cld,std
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&& !($opcode =~ /f[67]/ # grp 1
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&& $modrm =~ /^[2367abef]/) # mul, imul, div, idiv
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&& $modrm !~ /^$/) {
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print "ZZ ($file) opcode/modrm cross 32-byte boundary\n";
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}
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# with an 0F prefix, anything starting at 1f mod 20h
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if (($align==32 && $addr =~ /[13579bdf][f]$/
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|| $align==16 && $addr =~ /f$/
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|| $align==8 && $addr =~ /[7f]$/)
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&& $prefix =~ /0f/
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&& $opcode !~ /af/ # imul
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&& $opcode !~ /a[45]/ # shldl
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&& $opcode !~ /a[cd]/ # shrdl
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) {
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print "ZZ ($file) prefix/opcode cross 32-byte boundary\n";
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}
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# with an 0F prefix, anything with mod/rm starting at 1e mod 20h
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if (($align==32 && $addr =~ /[13579bdf][e]$/
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|| $align==16 && $addr =~ /[e]$/
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|| $align==8 && $addr =~ /[6e]$/)
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&& $prefix =~ /0f/
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&& $opcode !~ /^8/ # jcond disp32
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&& $opcode !~ /af/ # imull reg,reg
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&& $opcode !~ /a[45]/ # shldl
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&& $opcode !~ /a[cd]/ # shrdl
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&& $modrm !~ /^$/) {
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print "ZZ ($file) prefix/opcode/modrm cross 32-byte boundary\n";
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}
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}
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close IN || die "Error from objdump (or objdump not available)\n";
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}
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my @files;
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if ($#ARGV >= 0) {
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@files = @ARGV;
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} else {
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@files = glob "*.asm";
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map {s/.asm/.o/} @files;
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}
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foreach (@files) {
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disassemble($_);
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}
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