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/*
* ich9deblob.c
*
* Copyright (C) 2014 Steve Shenton <sgsit@libreboot.org>
* Francis Rowe <info@gluglug.org.uk>
*
* This program 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, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <string.h>
#include "ich9desc.c" // structs describing what's in the descriptor region
#include "ich9gbe.c" // structs describing what's in the gbe region
#define DESCRIPTORREGIONSIZE 0x1000 // 4096 bytes / 4KiB
#define GBEREGIONSIZE 0x2000 // 8192 bytes / 8KiB
unsigned short GetChecksum(char* buffer, unsigned short desiredValue); // for GBe region (checksum calculation)
unsigned short GetRegionWord(int i, char* buffer); // used for getting each word needed to calculate said checksum
int main(int argc, char *argv[])
{
// check compiler bit-packs in a compatible way
struct DESCRIPTORREGIONRECORD descriptorRegion;
unsigned int descriptorRegionStructSize = sizeof(descriptorRegion);
// basically, it is expected that this code will be used on x86
if (DESCRIPTORREGIONSIZE != descriptorRegionStructSize){
printf("\nerror: compiler incompatibility: descriptor struct length is %i bytes (should be %i)\n", descriptorRegionStructSize, DESCRIPTORREGIONSIZE);
return 1;
}
// supplied by user, dumped from their machine before flashing libreboot
char* factoryRomFilename = "factory.rom";
// name of the file that this utility will create (deblobbed descriptor+gbe)
char* deblobbedDescriptorFilename = "deblobbed_descriptor.bin";
// Open factory.rom, needed for extracting descriptor and gbe
// -----------------------------------------------
FILE* fp = NULL;
fp = fopen(factoryRomFilename, "rb"); // open factory.rom
if (NULL == fp)
{
printf("\nerror: could not open factory.rom\n");
return 1;
}
printf("\nfactory.rom opened successfully\n");
// -----------------------------------------------
// Create empty descriptor buffer (populated below)
char descriptorBuffer[DESCRIPTORREGIONSIZE];
// Extract the descriptor region from the factory.rom dump
// (goes in descriptorBuffer variable)
unsigned int readLen;
readLen = fread(descriptorBuffer, sizeof(char), DESCRIPTORREGIONSIZE, fp);
if (DESCRIPTORREGIONSIZE != readLen) //
{
printf("\nerror: could not read descriptor from factory.rom (%i) bytes read\n", readLen);
return 1;
}
printf("\ndescriptor region read successfully\n");
// copy descriptor buffer into descriptor struct memory
// descriptorRegion is an instance of a struct that actually
// defines the locations of all these variables in the descriptor,
// as defined in the datasheets. This allows us to map the extracted
// descriptor over the struct so that it can then be modified
// for libreboot's purpose
memcpy(&descriptorRegion, &descriptorBuffer, DESCRIPTORREGIONSIZE);
// get original GBe region location
// (it will be moved to the beginning of the flash, after the descriptor region)
unsigned int flRegionBitShift = 12;
unsigned int gbeRegionLocation = descriptorRegion.regionSection.flReg3.BASE << flRegionBitShift;
fseek(fp, gbeRegionLocation, SEEK_SET);
char gbeBuffer[GBEREGIONSIZE];
readLen = fread(gbeBuffer, sizeof(char), GBEREGIONSIZE, fp);
if (GBEREGIONSIZE != readLen)
{
printf("\nerror: could not read GBe region from factory.rom (%i) bytes read\n", readLen);
return 1;
}
// Get size of ROM image
// This is needed for relocating the BIOS region (per descriptor)
fseek(fp, 0L, SEEK_END);
int romSize = ftell(fp);
printf("\nfactory.rom size: [%i] bytes\n", romSize);
fclose(fp);
printf("\nOriginal Descriptor start block: %08x ; Descriptor end block: %08x\n", descriptorRegion.regionSection.flReg0.BASE << flRegionBitShift, descriptorRegion.regionSection.flReg0.LIMIT << flRegionBitShift);
printf("Original BIOS start block: %08x ; BIOS end block: %08x\n", descriptorRegion.regionSection.flReg1.BASE << flRegionBitShift, descriptorRegion.regionSection.flReg1.LIMIT << flRegionBitShift);
printf("Original ME start block: %08x ; ME end block: %08x\n", descriptorRegion.regionSection.flReg2.BASE << flRegionBitShift, descriptorRegion.regionSection.flReg2.LIMIT << flRegionBitShift);
printf("Original GBe start block: %08x ; GBe end block: %08x\n", gbeRegionLocation, descriptorRegion.regionSection.flReg3.LIMIT << flRegionBitShift);
// set number of regions from 4 -> 2 (0 based)
descriptorRegion.flMaps.flMap0.NR = 2;
// make descriptor writable from OS.
descriptorRegion.masterAccessSection.flMstr1.fdRegionWriteAccess = 1;
// relocate BIOS region and increase size to fill image
descriptorRegion.regionSection.flReg1.BASE = 3;
descriptorRegion.regionSection.flReg1.LIMIT = ((romSize / 0x1000) - 1);
// set ME region size to 0
descriptorRegion.regionSection.flReg2.BASE = 0xFFF;
descriptorRegion.regionSection.flReg2.LIMIT = 0;
// relocate Gbe region
descriptorRegion.regionSection.flReg3.BASE = 1;
descriptorRegion.regionSection.flReg3.LIMIT = 2;
// set Platform region size to 0
descriptorRegion.regionSection.flReg4.BASE = 0xFFF;
descriptorRegion.regionSection.flReg4.LIMIT = 0;
// disable ME in ICHSTRAP0
descriptorRegion.ichStraps.ichStrap0.meDisable = 1;
// disable ME and TPM in MCHSTRAP0
descriptorRegion.mchStraps.mchStrap0.meDisable = 1;
descriptorRegion.mchStraps.mchStrap0.tpmDisable = 1;
// disable ME, apart from chipset bugfixes (ME region still required)
//descriptorRegion.mchStraps.mchStrap0.meAlternateDisable = 1;
// debugging
printf("\nRelocated Descriptor start block: %08x ; Descriptor end block: %08x\n", descriptorRegion.regionSection.flReg0.BASE << flRegionBitShift, descriptorRegion.regionSection.flReg0.LIMIT << flRegionBitShift);
printf("Relocated BIOS start block: %08x ; BIOS end block: %08x\n", descriptorRegion.regionSection.flReg1.BASE << flRegionBitShift, descriptorRegion.regionSection.flReg1.LIMIT << flRegionBitShift);
printf("Relocated ME start block: %08x ; ME end block: %08x\n", descriptorRegion.regionSection.flReg2.BASE << flRegionBitShift, descriptorRegion.regionSection.flReg2.LIMIT << flRegionBitShift);
printf("Relocated GBe start block: %08x ; GBe end block: %08x\n", descriptorRegion.regionSection.flReg3.BASE << flRegionBitShift, descriptorRegion.regionSection.flReg3.LIMIT << flRegionBitShift);
char deblobbedDescriptorBuffer[DESCRIPTORREGIONSIZE];
memcpy(&deblobbedDescriptorBuffer, &descriptorRegion, DESCRIPTORREGIONSIZE);
remove(deblobbedDescriptorFilename);
fp = fopen(deblobbedDescriptorFilename, "ab");
if (DESCRIPTORREGIONSIZE != fwrite(deblobbedDescriptorBuffer, sizeof(char), DESCRIPTORREGIONSIZE, fp))
{
printf("\nerror: writing descriptor region failed\n");
return 1;
}
if (GBEREGIONSIZE != fwrite(gbeBuffer, sizeof(char), GBEREGIONSIZE, fp))
{
printf("\nerror: writing GBe region failed\n");
return 1;
}
fclose(fp);
printf("\ndeblobbed descriptor successfully created: deblobbed_descriptor.bin \n");
// calculate the 0x3F'th 16-bit uint to make the desired final checksum for GBe
// observed values (from actual factory.rom dumps) 0xBABA 0x3ABA 0x34BA. spec defined as 0xBABA.
// theoretically, this could be any l33t speak variation of BABA, eg 3434 or BA34, and so on, but this is untested. so far.
// 40BA was also observed in another factory dump for another X200 - this is not l33t speak.
// maybe only the 8 least significant bits are checked? or something deeper than that
unsigned short gbeCalculatedChecksum = GetChecksum(gbeBuffer, 0xBABA);
// get the actual 0x3F'th 16-bit uint that was already in the supplied (pre-compiled) region data
unsigned short gbeChecksum = GetRegionWord(0x3F, gbeBuffer);
printf("\ncalculated Gbe checksum: 0x%hx actual GBe checksum: 0x%hx\n", gbeCalculatedChecksum, gbeChecksum);
return 0;
}
unsigned short GetChecksum(char* regionData, unsigned short desiredValue)
{
unsigned short regionWord;
unsigned short checksum = 0;
int i;
for (i = 0; i < 0x3F; i++) {
regionWord = GetRegionWord(i, regionData);
checksum += regionWord;
}
checksum = desiredValue - checksum;
return checksum;
}
// Read a 16-bit unsigned int from a supplied region buffer
unsigned short GetRegionWord(int index, char* regionData)
{
return *((unsigned short*)(regionData + (index * 2)));
}
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