#!/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 <[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;
}
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