#!/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
  ";
  }
  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!
  ";

  	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
  ";
  		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 
  ";
  	exit;
  }

  if ($center == -1) {

  	print "No matching code found 
  ";
  	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 "
  ";

  	$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;
  }