linuxboot/fit-parse

#!/usr/bin/perl
use warnings;
use strict;

undef $/;
my $rom = <>;
my $base = 0xFFFFFFFF - length($rom) + 1;
printf "ROM len:  %08x\n", length($rom);
printf "ROM base: %08x\n", $base;

sub uint32
{
	my $offset = shift;
	return unpack("V", substr($rom, $offset - $base, 4));
}

sub uint64
{
	my $offset = shift;
	return unpack("Q", substr($rom, $offset - $base, 8));
}

# Assume the ROM is mapped to the top of 4GB
my $fit_ptr = uint32(0xFFFFFFC0);
my $fit_offset = $fit_ptr - $base;

printf "FIT pointer: %08x (offset %08x)\n", $fit_ptr, $fit_offset;

die "FIT pointer out of range?\n" if $fit_offset >= length($rom);

my $fit = substr($rom, $fit_ptr - $base, 8);
printf "Signature: '%s'\n", $fit;
die "Bad signature?\n" unless $fit eq '_FIT_   ';

my $entries = uint32($fit_ptr + 0x8);

my %entry_types = (
	0x00	=> "Header",
	0x01	=> "Microcode",
	0x02	=> "Startup ACM",
	0x07	=> "BIOS Startup Module",
	0x08	=> "TPM Policy",
	0x09	=> "BIOS Policy",
	0x0A	=> "TXT Policy",
	0x0B	=> "Key Manifest",
	0x0C	=> "Boot Policy Manifest",
	0x10	=> "CSE Secure Boot",
	0x2D	=> "TXTSX Policy",
	0x2F	=> "JMP Debug Policy",
	0x7F	=> "SKIP",
);

for my $i (1..$entries-1)
{
	my ($address, $len, $ver, $type, $csum) = unpack(
		"QVSCC", substr($rom, $fit_ptr - $base + $i*0x10, 0x10));

	printf "%d: address %08x @ %08x: ver %04x type %s (0x%02x)\n",
		$i,
		$address,
		$len,
		$ver,
		$entry_types{$type} || "Unknown",
		$type,
		;
}