[linux.git] / scripts / markup_oops.pl

#!/usr/bin/perl

use File::Basename;
use Math::BigInt;
use Getopt::Long;

# Copyright 2008, Intel Corporation
#
# This file is part of the Linux kernel
#
# This program file is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; version 2 of the License.
#
# Authors:
# 	Arjan van de Ven <[email protected]>


my $cross_compile = "";
my $vmlinux_name = "";
my $modulefile = "";

# Get options
Getopt::Long::GetOptions(
	'cross-compile|c=s'	=> \$cross_compile,
	'module|m=s'		=> \$modulefile,
	'help|h'		=> \&usage,
) || usage ();
my $vmlinux_name = $ARGV[0];
if (!defined($vmlinux_name)) {
	my $kerver = `uname -r`;
	chomp($kerver);
	$vmlinux_name = "/lib/modules/$kerver/build/vmlinux";
	print "No vmlinux specified, assuming $vmlinux_name\n";
}
my $filename = $vmlinux_name;

# Parse the oops to find the EIP value

my $target = "0";
my $function;
my $module = "";
my $func_offset = 0;
my $vmaoffset = 0;

my %regs;


sub parse_x86_regs
{
	my ($line) = @_;
	if ($line =~ /EAX: ([0-9a-f]+) EBX: ([0-9a-f]+) ECX: ([0-9a-f]+) EDX: ([0-9a-f]+)/) {
		$regs{"%eax"} = $1;
		$regs{"%ebx"} = $2;
		$regs{"%ecx"} = $3;
		$regs{"%edx"} = $4;
	}
	if ($line =~ /ESI: ([0-9a-f]+) EDI: ([0-9a-f]+) EBP: ([0-9a-f]+) ESP: ([0-9a-f]+)/) {
		$regs{"%esi"} = $1;
		$regs{"%edi"} = $2;
		$regs{"%esp"} = $4;
	}
	if ($line =~ /RAX: ([0-9a-f]+) RBX: ([0-9a-f]+) RCX: ([0-9a-f]+)/) {
		$regs{"%eax"} = $1;
		$regs{"%ebx"} = $2;
		$regs{"%ecx"} = $3;
	}
	if ($line =~ /RDX: ([0-9a-f]+) RSI: ([0-9a-f]+) RDI: ([0-9a-f]+)/) {
		$regs{"%edx"} = $1;
		$regs{"%esi"} = $2;
		$regs{"%edi"} = $3;
	}
	if ($line =~ /RBP: ([0-9a-f]+) R08: ([0-9a-f]+) R09: ([0-9a-f]+)/) {
		$regs{"%r08"} = $2;
		$regs{"%r09"} = $3;
	}
	if ($line =~ /R10: ([0-9a-f]+) R11: ([0-9a-f]+) R12: ([0-9a-f]+)/) {
		$regs{"%r10"} = $1;
		$regs{"%r11"} = $2;
		$regs{"%r12"} = $3;
	}
	if ($line =~ /R13: ([0-9a-f]+) R14: ([0-9a-f]+) R15: ([0-9a-f]+)/) {
		$regs{"%r13"} = $1;
		$regs{"%r14"} = $2;
		$regs{"%r15"} = $3;
	}
}

sub reg_name
{
	my ($reg) = @_;
	$reg =~ s/r(.)x/e\1x/;
	$reg =~ s/r(.)i/e\1i/;
	$reg =~ s/r(.)p/e\1p/;
	return $reg;
}

sub process_x86_regs
{
	my ($line, $cntr) = @_;
	my $str = "";
	if (length($line) < 40) {
		return ""; # not an asm istruction
	}

	# find the arguments to the instruction
	if ($line =~ /([0-9a-zA-Z\,\%\(\)\-\+]+)$/) {
		$lastword = $1;
	} else {
		return "";
	}

	# we need to find the registers that get clobbered,
	# since their value is no longer relevant for previous
	# instructions in the stream.

	$clobber = $lastword;
	# first, remove all memory operands, they're read only
	$clobber =~ s/\([a-z0-9\%\,]+\)//g;
	# then, remove everything before the comma, thats the read part
	$clobber =~ s/.*\,//g;

	# if this is the instruction that faulted, we haven't actually done
	# the write yet... nothing is clobbered.
	if ($cntr == 0) {
		$clobber = "";
	}

	foreach $reg (keys(%regs)) {
		my $clobberprime = reg_name($clobber);
		my $lastwordprime = reg_name($lastword);
		my $val = $regs{$reg};
		if ($val =~ /^[0]+$/) {
			$val = "0";
		} else {
			$val =~ s/^0*//;
		}

		# first check if we're clobbering this register; if we do
		# we print it with a =>, and then delete its value
		if ($clobber =~ /$reg/ || $clobberprime =~ /$reg/) {
			if (length($val) > 0) {
				$str = $str . " $reg => $val ";
			}
			$regs{$reg} = "";
			$val = "";
		}
		# now check if we're reading this register
		if ($lastword =~ /$reg/ || $lastwordprime =~ /$reg/) {
			if (length($val) > 0) {
				$str = $str . " $reg = $val ";
			}
		}
	}
	return $str;
}

# parse the oops
while (<STDIN>) {
	my $line = $_;
	if ($line =~ /EIP: 0060:\[\<([a-z0-9]+)\>\]/) {
		$target = $1;
	}
	if ($line =~ /RIP: 0010:\[\<([a-z0-9]+)\>\]/) {
		$target = $1;
	}
	if ($line =~ /EIP is at ([a-zA-Z0-9\_]+)\+0x([0-9a-f]+)\/0x[a-f0-9]/) {
		$function = $1;
		$func_offset = $2;
	}
	if ($line =~ /RIP: 0010:\[\<[0-9a-f]+\>\]  \[\<[0-9a-f]+\>\] ([a-zA-Z0-9\_]+)\+0x([0-9a-f]+)\/0x[a-f0-9]/) {
		$function = $1;
		$func_offset = $2;
	}

	# check if it's a module
	if ($line =~ /EIP is at ([a-zA-Z0-9\_]+)\+(0x[0-9a-f]+)\/0x[a-f0-9]+\W\[([a-zA-Z0-9\_\-]+)\]/) {
		$module = $3;
	}
	if ($line =~ /RIP: 0010:\[\<[0-9a-f]+\>\]  \[\<[0-9a-f]+\>\] ([a-zA-Z0-9\_]+)\+(0x[0-9a-f]+)\/0x[a-f0-9]+\W\[([a-zA-Z0-9\_\-]+)\]/) {
		$module = $3;
	}
	parse_x86_regs($line);
}

my $decodestart = Math::BigInt->from_hex("0x$target") - Math::BigInt->from_hex("0x$func_offset");
my $decodestop = Math::BigInt->from_hex("0x$target") + 8192;
if ($target eq "0") {
	print "No oops found!\n";
	usage();
}

# if it's a module, we need to find the .ko file and calculate a load offset
if ($module ne "") {
	if ($modulefile eq "") {
		$modulefile = `modinfo -F filename $module`;
		chomp($modulefile);
	}
	$filename = $modulefile;
	if ($filename eq "") {
		print "Module .ko file for $module not found. Aborting\n";
		exit;
	}
	# ok so we found the module, now we need to calculate the vma offset
	open(FILE, $cross_compile."objdump -dS $filename |") || die "Cannot start objdump";
	while (<FILE>) {
		if ($_ =~ /^([0-9a-f]+) \<$function\>\:/) {
			my $fu = $1;
			$vmaoffset = Math::BigInt->from_hex("0x$target") - Math::BigInt->from_hex("0x$fu") - Math::BigInt->from_hex("0x$func_offset");
		}
	}
	close(FILE);
}

my $counter = 0;
my $state   = 0;
my $center  = -1;
my @lines;
my @reglines;

sub InRange {
	my ($address, $target) = @_;
	my $ad = "0x".$address;
	my $ta = "0x".$target;
	my $delta = Math::BigInt->from_hex($ad) - Math::BigInt->from_hex($ta);

	if (($delta > -4096) && ($delta < 4096)) {
		return 1;
	}
	return 0;
}


# first, parse the input into the lines array, but to keep size down,
# we only do this for 4Kb around the sweet spot

open(FILE, $cross_compile."objdump -dS --adjust-vma=$vmaoffset --start-address=$decodestart --stop-address=$decodestop $filename |") || die "Cannot start objdump";

while (<FILE>) {
	my $line = $_;
	chomp($line);
	if ($state == 0) {
		if ($line =~ /^([a-f0-9]+)\:/) {
			if (InRange($1, $target)) {
				$state = 1;
			}
		}
	}
	if ($state == 1) {
		if ($line =~ /^([a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]+)\:/) {
			my $val = $1;
			if (!InRange($val, $target)) {
				last;
			}
			if ($val eq $target) {
				$center = $counter;
			}
		}
		$lines[$counter] = $line;

		$counter = $counter + 1;
	}
}

close(FILE);

if ($counter == 0) {
	print "No matching code found \n";
	exit;
}

if ($center == -1) {
	print "No matching code found \n";
	exit;
}

my $start;
my $finish;
my $codelines = 0;
my $binarylines = 0;
# now we go up and down in the array to find how much we want to print

$start = $center;

while ($start > 1) {
	$start = $start - 1;
	my $line = $lines[$start];
	if ($line =~ /^([a-f0-9]+)\:/) {
		$binarylines = $binarylines + 1;
	} else {
		$codelines = $codelines + 1;
	}
	if ($codelines > 10) {
		last;
	}
	if ($binarylines > 20) {
		last;
	}
}


$finish = $center;
$codelines = 0;
$binarylines = 0;
while ($finish < $counter) {
	$finish = $finish + 1;
	my $line = $lines[$finish];
	if ($line =~ /^([a-f0-9]+)\:/) {
		$binarylines = $binarylines + 1;
	} else {
		$codelines = $codelines + 1;
	}
	if ($codelines > 10) {
		last;
	}
	if ($binarylines > 20) {
		last;
	}
}


my $i;


# start annotating the registers in the asm.
# this goes from the oopsing point back, so that the annotator
# can track (opportunistically) which registers got written and
# whos value no longer is relevant.

$i = $center;
while ($i >= $start) {
	$reglines[$i] = process_x86_regs($lines[$i], $center - $i);
	$i = $i - 1;
}

$i = $start;
while ($i < $finish) {
	my $line;
	if ($i == $center) {
		$line =  "*$lines[$i] ";
	} else {
		$line =  " $lines[$i] ";
	}
	print $line;
	if (defined($reglines[$i]) && length($reglines[$i]) > 0) {
		my $c = 60 - length($line);
		while ($c > 0) { print " "; $c = $c - 1; };
		print "| $reglines[$i]";
	}
	if ($i == $center) {
		print "<--- faulting instruction";
	}
	print "\n";
	$i = $i +1;
}

sub usage {
	print <<EOT;
Usage:
  dmesg | perl $0 [OPTION] [VMLINUX]

OPTION:
  -c, --cross-compile CROSS_COMPILE	Specify the prefix used for toolchain.
  -m, --module MODULE_DIRNAME		Specify the module filename.
  -h, --help				Help.
EOT
	exit;
}
Commit	Line	Data
11df65c3	1	#!/usr/bin/perl
5aea50b5	2
d32ad102	3	use File::Basename;
51fbb4ba	4	use Math::BigInt;
52e13e21	5	use Getopt::Long;
d32ad102	6
5aea50b5 AV	7	# Copyright 2008, Intel Corporation
	8	#
	9	# This file is part of the Linux kernel
	10	#
	11	# This program file is free software; you can redistribute it and/or modify it
	12	# under the terms of the GNU General Public License as published by the
	13	# Free Software Foundation; version 2 of the License.
	14	#
	15	# Authors:
	16	# Arjan van de Ven <[email protected]>
	17
	18
52e13e21 HZ	19	my $cross_compile = "";
	20	my $vmlinux_name = "";
	21	my $modulefile = "";
	22
	23	# Get options
	24	Getopt::Long::GetOptions(
	25	'cross-compile\|c=s' => \$cross_compile,
59dde385	26	'module\|m=s' => \$modulefile,
52e13e21	27	'help\|h' => \&usage,
59dde385	28	) \|\| usage ();
5aea50b5	29	my $vmlinux_name = $ARGV[0];
d32ad102 AV	30	if (!defined($vmlinux_name)) {
	31	my $kerver = `uname -r`;
	32	chomp($kerver);
	33	$vmlinux_name = "/lib/modules/$kerver/build/vmlinux";
	34	print "No vmlinux specified, assuming $vmlinux_name\n";
	35	}
	36	my $filename = $vmlinux_name;
52e13e21 HZ	37
52e13e21 HZ	38	# Parse the oops to find the EIP value
5aea50b5 AV	39
5aea50b5 AV	40	my $target = "0";
d32ad102 AV	41	my $function;
d32ad102 AV	42	my $module = "";
11df65c3	43	my $func_offset = 0;
d32ad102 AV	44	my $vmaoffset = 0;
d32ad102 AV	45
c19ef7fd AV	46	my %regs;
	47
	48
	49	sub parse_x86_regs
	50	{
	51	my ($line) = @_;
	52	if ($line =~ /EAX: ([0-9a-f]+) EBX: ([0-9a-f]+) ECX: ([0-9a-f]+) EDX: ([0-9a-f]+)/) {
	53	$regs{"%eax"} = $1;
	54	$regs{"%ebx"} = $2;
	55	$regs{"%ecx"} = $3;
	56	$regs{"%edx"} = $4;
	57	}
	58	if ($line =~ /ESI: ([0-9a-f]+) EDI: ([0-9a-f]+) EBP: ([0-9a-f]+) ESP: ([0-9a-f]+)/) {
	59	$regs{"%esi"} = $1;
	60	$regs{"%edi"} = $2;
	61	$regs{"%esp"} = $4;
	62	}
11df65c3 AV	63	if ($line =~ /RAX: ([0-9a-f]+) RBX: ([0-9a-f]+) RCX: ([0-9a-f]+)/) {
	64	$regs{"%eax"} = $1;
	65	$regs{"%ebx"} = $2;
	66	$regs{"%ecx"} = $3;
	67	}
	68	if ($line =~ /RDX: ([0-9a-f]+) RSI: ([0-9a-f]+) RDI: ([0-9a-f]+)/) {
	69	$regs{"%edx"} = $1;
	70	$regs{"%esi"} = $2;
	71	$regs{"%edi"} = $3;
	72	}
	73	if ($line =~ /RBP: ([0-9a-f]+) R08: ([0-9a-f]+) R09: ([0-9a-f]+)/) {
	74	$regs{"%r08"} = $2;
	75	$regs{"%r09"} = $3;
	76	}
	77	if ($line =~ /R10: ([0-9a-f]+) R11: ([0-9a-f]+) R12: ([0-9a-f]+)/) {
	78	$regs{"%r10"} = $1;
	79	$regs{"%r11"} = $2;
	80	$regs{"%r12"} = $3;
	81	}
	82	if ($line =~ /R13: ([0-9a-f]+) R14: ([0-9a-f]+) R15: ([0-9a-f]+)/) {
	83	$regs{"%r13"} = $1;
	84	$regs{"%r14"} = $2;
	85	$regs{"%r15"} = $3;
	86	}
	87	}
	88
	89	sub reg_name
	90	{
	91	my ($reg) = @_;
	92	$reg =~ s/r(.)x/e\1x/;
	93	$reg =~ s/r(.)i/e\1i/;
	94	$reg =~ s/r(.)p/e\1p/;
	95	return $reg;
c19ef7fd AV	96	}
	97
	98	sub process_x86_regs
	99	{
	100	my ($line, $cntr) = @_;
	101	my $str = "";
	102	if (length($line) < 40) {
	103	return ""; # not an asm istruction
	104	}
	105
	106	# find the arguments to the instruction
	107	if ($line =~ /([0-9a-zA-Z\,\%\(\)\-\+]+)$/) {
	108	$lastword = $1;
	109	} else {
	110	return "";
	111	}
	112
	113	# we need to find the registers that get clobbered,
	114	# since their value is no longer relevant for previous
	115	# instructions in the stream.
	116
	117	$clobber = $lastword;
	118	# first, remove all memory operands, they're read only
	119	$clobber =~ s/\([a-z0-9\%\,]+\)//g;
	120	# then, remove everything before the comma, thats the read part
	121	$clobber =~ s/.*\,//g;
	122
	123	# if this is the instruction that faulted, we haven't actually done
	124	# the write yet... nothing is clobbered.
	125	if ($cntr == 0) {
	126	$clobber = "";
	127	}
	128
	129	foreach $reg (keys(%regs)) {
11df65c3 AV	130	my $clobberprime = reg_name($clobber);
11df65c3 AV	131	my $lastwordprime = reg_name($lastword);
c19ef7fd	132	my $val = $regs{$reg};
11df65c3 AV	133	if ($val =~ /^[0]+$/) {
	134	$val = "0";
	135	} else {
	136	$val =~ s/^0*//;
	137	}
	138
c19ef7fd AV	139	# first check if we're clobbering this register; if we do
c19ef7fd AV	140	# we print it with a =>, and then delete its value
11df65c3	141	if ($clobber =~ /$reg/ \|\| $clobberprime =~ /$reg/) {
c19ef7fd AV	142	if (length($val) > 0) {
	143	$str = $str . " $reg => $val ";
	144	}
	145	$regs{$reg} = "";
	146	$val = "";
	147	}
	148	# now check if we're reading this register
11df65c3	149	if ($lastword =~ /$reg/ \|\| $lastwordprime =~ /$reg/) {
c19ef7fd AV	150	if (length($val) > 0) {
	151	$str = $str . " $reg = $val ";
	152	}
	153	}
	154	}
	155	return $str;
	156	}
	157
	158	# parse the oops
5aea50b5	159	while (<STDIN>) {
d32ad102 AV	160	my $line = $_;
d32ad102 AV	161	if ($line =~ /EIP: 0060:\[\<([a-z0-9]+)\>\]/) {
5aea50b5 AV	162	$target = $1;
5aea50b5 AV	163	}
11df65c3 AV	164	if ($line =~ /RIP: 0010:\[\<([a-z0-9]+)\>\]/) {
	165	$target = $1;
	166	}
1f8cdae4	167	if ($line =~ /EIP is at ([a-zA-Z0-9\_]+)\+0x([0-9a-f]+)\/0x[a-f0-9]/) {
d32ad102 AV	168	$function = $1;
	169	$func_offset = $2;
	170	}
ef2b9b05	171	if ($line =~ /RIP: 0010:\[\<[0-9a-f]+\>\] \[\<[0-9a-f]+\>\] ([a-zA-Z0-9\_]+)\+0x([0-9a-f]+)\/0x[a-f0-9]/) {
11df65c3 AV	172	$function = $1;
	173	$func_offset = $2;
	174	}
5aea50b5	175
d32ad102 AV	176	# check if it's a module
	177	if ($line =~ /EIP is at ([a-zA-Z0-9\_]+)\+(0x[0-9a-f]+)\/0x[a-f0-9]+\W\[([a-zA-Z0-9\_\-]+)\]/) {
	178	$module = $3;
	179	}
11df65c3 AV	180	if ($line =~ /RIP: 0010:\[\<[0-9a-f]+\>\] \[\<[0-9a-f]+\>\] ([a-zA-Z0-9\_]+)\+(0x[0-9a-f]+)\/0x[a-f0-9]+\W\[([a-zA-Z0-9\_\-]+)\]/) {
	181	$module = $3;
	182	}
c19ef7fd	183	parse_x86_regs($line);
5aea50b5 AV	184	}
5aea50b5 AV	185
51fbb4ba MW	186	my $decodestart = Math::BigInt->from_hex("0x$target") - Math::BigInt->from_hex("0x$func_offset");
51fbb4ba MW	187	my $decodestop = Math::BigInt->from_hex("0x$target") + 8192;
5aea50b5 AV	188	if ($target eq "0") {
5aea50b5 AV	189	print "No oops found!\n";
52e13e21	190	usage();
5aea50b5 AV	191	}
5aea50b5 AV	192
d32ad102 AV	193	# if it's a module, we need to find the .ko file and calculate a load offset
d32ad102 AV	194	if ($module ne "") {
52e13e21	195	if ($modulefile eq "") {
59dde385	196	$modulefile = `modinfo -F filename $module`;
52e13e21 HZ	197	chomp($modulefile);
52e13e21 HZ	198	}
d32ad102 AV	199	$filename = $modulefile;
	200	if ($filename eq "") {
	201	print "Module .ko file for $module not found. Aborting\n";
	202	exit;
	203	}
	204	# ok so we found the module, now we need to calculate the vma offset
52e13e21	205	open(FILE, $cross_compile."objdump -dS $filename \|") \|\| die "Cannot start objdump";
d32ad102 AV	206	while (<FILE>) {
	207	if ($_ =~ /^([0-9a-f]+) \<$function\>\:/) {
	208	my $fu = $1;
52e13e21	209	$vmaoffset = Math::BigInt->from_hex("0x$target") - Math::BigInt->from_hex("0x$fu") - Math::BigInt->from_hex("0x$func_offset");
d32ad102 AV	210	}
	211	}
	212	close(FILE);
	213	}
	214
5aea50b5 AV	215	my $counter = 0;
5aea50b5 AV	216	my $state = 0;
0139f1d9	217	my $center = -1;
5aea50b5	218	my @lines;
c19ef7fd	219	my @reglines;
5aea50b5 AV	220
	221	sub InRange {
	222	my ($address, $target) = @_;
	223	my $ad = "0x".$address;
	224	my $ta = "0x".$target;
52e13e21	225	my $delta = Math::BigInt->from_hex($ad) - Math::BigInt->from_hex($ta);
5aea50b5 AV	226
	227	if (($delta > -4096) && ($delta < 4096)) {
	228	return 1;
	229	}
	230	return 0;
	231	}
	232
	233
	234
	235	# first, parse the input into the lines array, but to keep size down,
	236	# we only do this for 4Kb around the sweet spot
	237
52e13e21	238	open(FILE, $cross_compile."objdump -dS --adjust-vma=$vmaoffset --start-address=$decodestart --stop-address=$decodestop $filename \|") \|\| die "Cannot start objdump";
5aea50b5 AV	239
	240	while (<FILE>) {
	241	my $line = $_;
	242	chomp($line);
	243	if ($state == 0) {
	244	if ($line =~ /^([a-f0-9]+)\:/) {
	245	if (InRange($1, $target)) {
	246	$state = 1;
	247	}
	248	}
0139f1d9 HZ	249	}
0139f1d9 HZ	250	if ($state == 1) {
5aea50b5 AV	251	if ($line =~ /^([a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]+)\:/) {
	252	my $val = $1;
	253	if (!InRange($val, $target)) {
	254	last;
	255	}
	256	if ($val eq $target) {
	257	$center = $counter;
	258	}
	259	}
	260	$lines[$counter] = $line;
	261
	262	$counter = $counter + 1;
	263	}
	264	}
	265
	266	close(FILE);
	267
	268	if ($counter == 0) {
	269	print "No matching code found \n";
	270	exit;
	271	}
	272
0139f1d9	273	if ($center == -1) {
5aea50b5 AV	274	print "No matching code found \n";
	275	exit;
	276	}
	277
	278	my $start;
	279	my $finish;
	280	my $codelines = 0;
	281	my $binarylines = 0;
	282	# now we go up and down in the array to find how much we want to print
	283
	284	$start = $center;
	285
	286	while ($start > 1) {
	287	$start = $start - 1;
	288	my $line = $lines[$start];
	289	if ($line =~ /^([a-f0-9]+)\:/) {
	290	$binarylines = $binarylines + 1;
	291	} else {
	292	$codelines = $codelines + 1;
	293	}
	294	if ($codelines > 10) {
	295	last;
	296	}
	297	if ($binarylines > 20) {
	298	last;
	299	}
	300	}
	301
	302
	303	$finish = $center;
	304	$codelines = 0;
	305	$binarylines = 0;
	306	while ($finish < $counter) {
	307	$finish = $finish + 1;
	308	my $line = $lines[$finish];
	309	if ($line =~ /^([a-f0-9]+)\:/) {
	310	$binarylines = $binarylines + 1;
	311	} else {
	312	$codelines = $codelines + 1;
	313	}
	314	if ($codelines > 10) {
	315	last;
	316	}
	317	if ($binarylines > 20) {
	318	last;
	319	}
	320	}
	321
	322
	323	my $i;
	324
c19ef7fd AV	325
	326	# start annotating the registers in the asm.
	327	# this goes from the oopsing point back, so that the annotator
	328	# can track (opportunistically) which registers got written and
	329	# whos value no longer is relevant.
	330
	331	$i = $center;
	332	while ($i >= $start) {
	333	$reglines[$i] = process_x86_regs($lines[$i], $center - $i);
	334	$i = $i - 1;
	335	}
	336
5aea50b5 AV	337	$i = $start;
5aea50b5 AV	338	while ($i < $finish) {
c19ef7fd	339	my $line;
5aea50b5	340	if ($i == $center) {
c19ef7fd	341	$line = "*$lines[$i] ";
5aea50b5	342	} else {
c19ef7fd AV	343	$line = " $lines[$i] ";
	344	}
	345	print $line;
	346	if (defined($reglines[$i]) && length($reglines[$i]) > 0) {
	347	my $c = 60 - length($line);
	348	while ($c > 0) { print " "; $c = $c - 1; };
	349	print "\| $reglines[$i]";
5aea50b5	350	}
c19ef7fd AV	351	if ($i == $center) {
	352	print "<--- faulting instruction";
	353	}
	354	print "\n";
5aea50b5 AV	355	$i = $i +1;
	356	}
	357
52e13e21 HZ	358	sub usage {
	359	print <<EOT;
	360	Usage:
	361	dmesg \| perl $0 [OPTION] [VMLINUX]
	362
	363	OPTION:
	364	-c, --cross-compile CROSS_COMPILE Specify the prefix used for toolchain.
59dde385	365	-m, --module MODULE_DIRNAME Specify the module filename.
52e13e21 HZ	366	-h, --help Help.
	367	EOT
	368	exit;
	369	}