[thirdparty/kernel/stable.git] / scripts / markup_oops.pl

#!/usr/bin/env perl
# SPDX-License-Identifier: GPL-2.0-only

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

# Copyright 2008, Intel Corporation
#
# This file is part of the Linux kernel
#
# Authors:
# 	Arjan van de Ven <arjan@linux.intel.com>


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
cb77f0d6	1	#!/usr/bin/env perl
76e692f5	2	# SPDX-License-Identifier: GPL-2.0-only
5aea50b5	3
d32ad102	4	use File::Basename;
51fbb4ba	5	use Math::BigInt;
52e13e21	6	use Getopt::Long;
d32ad102	7
5aea50b5 AV	8	# Copyright 2008, Intel Corporation
	9	#
	10	# This file is part of the Linux kernel
	11	#
5aea50b5 AV	12	# Authors:
	13	# Arjan van de Ven <arjan@linux.intel.com>
	14
	15
52e13e21 HZ	16	my $cross_compile = "";
	17	my $vmlinux_name = "";
	18	my $modulefile = "";
	19
	20	# Get options
	21	Getopt::Long::GetOptions(
	22	'cross-compile\|c=s' => \$cross_compile,
59dde385	23	'module\|m=s' => \$modulefile,
52e13e21	24	'help\|h' => \&usage,
59dde385	25	) \|\| usage ();
5aea50b5	26	my $vmlinux_name = $ARGV[0];
d32ad102 AV	27	if (!defined($vmlinux_name)) {
	28	my $kerver = `uname -r`;
	29	chomp($kerver);
	30	$vmlinux_name = "/lib/modules/$kerver/build/vmlinux";
	31	print "No vmlinux specified, assuming $vmlinux_name\n";
	32	}
	33	my $filename = $vmlinux_name;
52e13e21 HZ	34
52e13e21 HZ	35	# Parse the oops to find the EIP value
5aea50b5 AV	36
5aea50b5 AV	37	my $target = "0";
d32ad102 AV	38	my $function;
d32ad102 AV	39	my $module = "";
11df65c3	40	my $func_offset = 0;
d32ad102 AV	41	my $vmaoffset = 0;
d32ad102 AV	42
c19ef7fd AV	43	my %regs;
	44
	45
	46	sub parse_x86_regs
	47	{
	48	my ($line) = @_;
	49	if ($line =~ /EAX: ([0-9a-f]+) EBX: ([0-9a-f]+) ECX: ([0-9a-f]+) EDX: ([0-9a-f]+)/) {
	50	$regs{"%eax"} = $1;
	51	$regs{"%ebx"} = $2;
	52	$regs{"%ecx"} = $3;
	53	$regs{"%edx"} = $4;
	54	}
	55	if ($line =~ /ESI: ([0-9a-f]+) EDI: ([0-9a-f]+) EBP: ([0-9a-f]+) ESP: ([0-9a-f]+)/) {
	56	$regs{"%esi"} = $1;
	57	$regs{"%edi"} = $2;
	58	$regs{"%esp"} = $4;
	59	}
11df65c3 AV	60	if ($line =~ /RAX: ([0-9a-f]+) RBX: ([0-9a-f]+) RCX: ([0-9a-f]+)/) {
	61	$regs{"%eax"} = $1;
	62	$regs{"%ebx"} = $2;
	63	$regs{"%ecx"} = $3;
	64	}
	65	if ($line =~ /RDX: ([0-9a-f]+) RSI: ([0-9a-f]+) RDI: ([0-9a-f]+)/) {
	66	$regs{"%edx"} = $1;
	67	$regs{"%esi"} = $2;
	68	$regs{"%edi"} = $3;
	69	}
	70	if ($line =~ /RBP: ([0-9a-f]+) R08: ([0-9a-f]+) R09: ([0-9a-f]+)/) {
	71	$regs{"%r08"} = $2;
	72	$regs{"%r09"} = $3;
	73	}
	74	if ($line =~ /R10: ([0-9a-f]+) R11: ([0-9a-f]+) R12: ([0-9a-f]+)/) {
	75	$regs{"%r10"} = $1;
	76	$regs{"%r11"} = $2;
	77	$regs{"%r12"} = $3;
	78	}
	79	if ($line =~ /R13: ([0-9a-f]+) R14: ([0-9a-f]+) R15: ([0-9a-f]+)/) {
	80	$regs{"%r13"} = $1;
	81	$regs{"%r14"} = $2;
	82	$regs{"%r15"} = $3;
	83	}
	84	}
	85
	86	sub reg_name
	87	{
	88	my ($reg) = @_;
	89	$reg =~ s/r(.)x/e\1x/;
	90	$reg =~ s/r(.)i/e\1i/;
	91	$reg =~ s/r(.)p/e\1p/;
	92	return $reg;
c19ef7fd AV	93	}
	94
	95	sub process_x86_regs
	96	{
	97	my ($line, $cntr) = @_;
	98	my $str = "";
	99	if (length($line) < 40) {
	100	return ""; # not an asm istruction
	101	}
	102
	103	# find the arguments to the instruction
	104	if ($line =~ /([0-9a-zA-Z\,\%\(\)\-\+]+)$/) {
	105	$lastword = $1;
	106	} else {
	107	return "";
	108	}
	109
	110	# we need to find the registers that get clobbered,
	111	# since their value is no longer relevant for previous
	112	# instructions in the stream.
	113
	114	$clobber = $lastword;
	115	# first, remove all memory operands, they're read only
	116	$clobber =~ s/\([a-z0-9\%\,]+\)//g;
	117	# then, remove everything before the comma, thats the read part
	118	$clobber =~ s/.*\,//g;
	119
	120	# if this is the instruction that faulted, we haven't actually done
	121	# the write yet... nothing is clobbered.
	122	if ($cntr == 0) {
	123	$clobber = "";
	124	}
	125
	126	foreach $reg (keys(%regs)) {
11df65c3 AV	127	my $clobberprime = reg_name($clobber);
11df65c3 AV	128	my $lastwordprime = reg_name($lastword);
c19ef7fd	129	my $val = $regs{$reg};
11df65c3 AV	130	if ($val =~ /^[0]+$/) {
	131	$val = "0";
	132	} else {
	133	$val =~ s/^0*//;
	134	}
	135
c19ef7fd AV	136	# first check if we're clobbering this register; if we do
c19ef7fd AV	137	# we print it with a =>, and then delete its value
11df65c3	138	if ($clobber =~ /$reg/ \|\| $clobberprime =~ /$reg/) {
c19ef7fd AV	139	if (length($val) > 0) {
	140	$str = $str . " $reg => $val ";
	141	}
	142	$regs{$reg} = "";
	143	$val = "";
	144	}
	145	# now check if we're reading this register
11df65c3	146	if ($lastword =~ /$reg/ \|\| $lastwordprime =~ /$reg/) {
c19ef7fd AV	147	if (length($val) > 0) {
	148	$str = $str . " $reg = $val ";
	149	}
	150	}
	151	}
	152	return $str;
	153	}
	154
	155	# parse the oops
5aea50b5	156	while (<STDIN>) {
d32ad102 AV	157	my $line = $_;
d32ad102 AV	158	if ($line =~ /EIP: 0060:\[\<([a-z0-9]+)\>\]/) {
5aea50b5 AV	159	$target = $1;
5aea50b5 AV	160	}
11df65c3 AV	161	if ($line =~ /RIP: 0010:\[\<([a-z0-9]+)\>\]/) {
	162	$target = $1;
	163	}
1f8cdae4	164	if ($line =~ /EIP is at ([a-zA-Z0-9\_]+)\+0x([0-9a-f]+)\/0x[a-f0-9]/) {
d32ad102 AV	165	$function = $1;
	166	$func_offset = $2;
	167	}
ef2b9b05	168	if ($line =~ /RIP: 0010:\[\<[0-9a-f]+\>\] \[\<[0-9a-f]+\>\] ([a-zA-Z0-9\_]+)\+0x([0-9a-f]+)\/0x[a-f0-9]/) {
11df65c3 AV	169	$function = $1;
	170	$func_offset = $2;
	171	}
5aea50b5	172
d32ad102 AV	173	# check if it's a module
	174	if ($line =~ /EIP is at ([a-zA-Z0-9\_]+)\+(0x[0-9a-f]+)\/0x[a-f0-9]+\W\[([a-zA-Z0-9\_\-]+)\]/) {
	175	$module = $3;
	176	}
11df65c3 AV	177	if ($line =~ /RIP: 0010:\[\<[0-9a-f]+\>\] \[\<[0-9a-f]+\>\] ([a-zA-Z0-9\_]+)\+(0x[0-9a-f]+)\/0x[a-f0-9]+\W\[([a-zA-Z0-9\_\-]+)\]/) {
	178	$module = $3;
	179	}
c19ef7fd	180	parse_x86_regs($line);
5aea50b5 AV	181	}
5aea50b5 AV	182
51fbb4ba MW	183	my $decodestart = Math::BigInt->from_hex("0x$target") - Math::BigInt->from_hex("0x$func_offset");
51fbb4ba MW	184	my $decodestop = Math::BigInt->from_hex("0x$target") + 8192;
5aea50b5 AV	185	if ($target eq "0") {
5aea50b5 AV	186	print "No oops found!\n";
52e13e21	187	usage();
5aea50b5 AV	188	}
5aea50b5 AV	189
d32ad102 AV	190	# if it's a module, we need to find the .ko file and calculate a load offset
d32ad102 AV	191	if ($module ne "") {
52e13e21	192	if ($modulefile eq "") {
59dde385	193	$modulefile = `modinfo -F filename $module`;
52e13e21 HZ	194	chomp($modulefile);
52e13e21 HZ	195	}
d32ad102 AV	196	$filename = $modulefile;
	197	if ($filename eq "") {
	198	print "Module .ko file for $module not found. Aborting\n";
	199	exit;
	200	}
	201	# ok so we found the module, now we need to calculate the vma offset
52e13e21	202	open(FILE, $cross_compile."objdump -dS $filename \|") \|\| die "Cannot start objdump";
d32ad102 AV	203	while (<FILE>) {
	204	if ($_ =~ /^([0-9a-f]+) \<$function\>\:/) {
	205	my $fu = $1;
52e13e21	206	$vmaoffset = Math::BigInt->from_hex("0x$target") - Math::BigInt->from_hex("0x$fu") - Math::BigInt->from_hex("0x$func_offset");
d32ad102 AV	207	}
	208	}
	209	close(FILE);
	210	}
	211
5aea50b5 AV	212	my $counter = 0;
5aea50b5 AV	213	my $state = 0;
0139f1d9	214	my $center = -1;
5aea50b5	215	my @lines;
c19ef7fd	216	my @reglines;
5aea50b5 AV	217
	218	sub InRange {
	219	my ($address, $target) = @_;
	220	my $ad = "0x".$address;
	221	my $ta = "0x".$target;
52e13e21	222	my $delta = Math::BigInt->from_hex($ad) - Math::BigInt->from_hex($ta);
5aea50b5 AV	223
	224	if (($delta > -4096) && ($delta < 4096)) {
	225	return 1;
	226	}
	227	return 0;
	228	}
	229
	230
	231
	232	# first, parse the input into the lines array, but to keep size down,
	233	# we only do this for 4Kb around the sweet spot
	234
52e13e21	235	open(FILE, $cross_compile."objdump -dS --adjust-vma=$vmaoffset --start-address=$decodestart --stop-address=$decodestop $filename \|") \|\| die "Cannot start objdump";
5aea50b5 AV	236
	237	while (<FILE>) {
	238	my $line = $_;
	239	chomp($line);
	240	if ($state == 0) {
	241	if ($line =~ /^([a-f0-9]+)\:/) {
	242	if (InRange($1, $target)) {
	243	$state = 1;
	244	}
	245	}
0139f1d9 HZ	246	}
0139f1d9 HZ	247	if ($state == 1) {
5aea50b5 AV	248	if ($line =~ /^([a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9][a-f0-9]+)\:/) {
	249	my $val = $1;
	250	if (!InRange($val, $target)) {
	251	last;
	252	}
	253	if ($val eq $target) {
	254	$center = $counter;
	255	}
	256	}
	257	$lines[$counter] = $line;
	258
	259	$counter = $counter + 1;
	260	}
	261	}
	262
	263	close(FILE);
	264
	265	if ($counter == 0) {
	266	print "No matching code found \n";
	267	exit;
	268	}
	269
0139f1d9	270	if ($center == -1) {
5aea50b5 AV	271	print "No matching code found \n";
	272	exit;
	273	}
	274
	275	my $start;
	276	my $finish;
	277	my $codelines = 0;
	278	my $binarylines = 0;
	279	# now we go up and down in the array to find how much we want to print
	280
	281	$start = $center;
	282
	283	while ($start > 1) {
	284	$start = $start - 1;
	285	my $line = $lines[$start];
	286	if ($line =~ /^([a-f0-9]+)\:/) {
	287	$binarylines = $binarylines + 1;
	288	} else {
	289	$codelines = $codelines + 1;
	290	}
	291	if ($codelines > 10) {
	292	last;
	293	}
	294	if ($binarylines > 20) {
	295	last;
	296	}
	297	}
	298
	299
	300	$finish = $center;
	301	$codelines = 0;
	302	$binarylines = 0;
	303	while ($finish < $counter) {
	304	$finish = $finish + 1;
	305	my $line = $lines[$finish];
	306	if ($line =~ /^([a-f0-9]+)\:/) {
	307	$binarylines = $binarylines + 1;
	308	} else {
	309	$codelines = $codelines + 1;
	310	}
	311	if ($codelines > 10) {
	312	last;
	313	}
	314	if ($binarylines > 20) {
	315	last;
	316	}
	317	}
	318
	319
	320	my $i;
	321
c19ef7fd AV	322
	323	# start annotating the registers in the asm.
	324	# this goes from the oopsing point back, so that the annotator
	325	# can track (opportunistically) which registers got written and
	326	# whos value no longer is relevant.
	327
	328	$i = $center;
	329	while ($i >= $start) {
	330	$reglines[$i] = process_x86_regs($lines[$i], $center - $i);
	331	$i = $i - 1;
	332	}
	333
5aea50b5 AV	334	$i = $start;
5aea50b5 AV	335	while ($i < $finish) {
c19ef7fd	336	my $line;
5aea50b5	337	if ($i == $center) {
c19ef7fd	338	$line = "*$lines[$i] ";
5aea50b5	339	} else {
c19ef7fd AV	340	$line = " $lines[$i] ";
	341	}
	342	print $line;
	343	if (defined($reglines[$i]) && length($reglines[$i]) > 0) {
	344	my $c = 60 - length($line);
	345	while ($c > 0) { print " "; $c = $c - 1; };
	346	print "\| $reglines[$i]";
5aea50b5	347	}
c19ef7fd AV	348	if ($i == $center) {
	349	print "<--- faulting instruction";
	350	}
	351	print "\n";
5aea50b5 AV	352	$i = $i +1;
	353	}
	354
52e13e21 HZ	355	sub usage {
	356	print <<EOT;
	357	Usage:
	358	dmesg \| perl $0 [OPTION] [VMLINUX]
	359
	360	OPTION:
	361	-c, --cross-compile CROSS_COMPILE Specify the prefix used for toolchain.
59dde385	362	-m, --module MODULE_DIRNAME Specify the module filename.
52e13e21 HZ	363	-h, --help Help.
	364	EOT
	365	exit;
	366	}