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/*
* descriptor/descriptor.c
* This file is part of the ich9deblob utility from the libreboot project
*
* 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/>.
*/
/*
* Provide descriptor related functions.
*/
/* structs describing the data in descriptor region */
#include "descriptor.h"
/*
* ---------------------------------------------------------------------
* Descriptor functions
* ---------------------------------------------------------------------
*/
/*
* Modify the flash descriptor, to remove the ME/AMT, and disable all other regions
* Only Flash Descriptor, Gbe and BIOS regions (BIOS region fills factoryRomSize-12k) are left.
* Tested on ThinkPad X200 and X200S. X200T and other GM45 targets may also work.
* Also described in docs/hcl/x200_remove_me.html
*/
struct DESCRIPTORREGIONRECORD deblobbedDescriptorStructFromFactory(struct DESCRIPTORREGIONRECORD factoryDescriptorStruct, unsigned int factoryRomSize)
{
struct DESCRIPTORREGIONRECORD deblobbedDescriptorStruct;
memcpy(&deblobbedDescriptorStruct, &factoryDescriptorStruct, DESCRIPTORREGIONSIZE);
/*
* set number of regions from 4 -> 2 (0 based, so 4 means 5 and 2
* means 3. We want 3 regions: descriptor, gbe and bios, in that order)
*/
deblobbedDescriptorStruct.flMaps.flMap0.NR = 2;
/*
* make descriptor writable from OS. This is that the user can run:
* sudo ./flashrom -p internal:laptop=force_I_want_a_brick
* from the OS, without relying an an external SPI flasher, while
* being able to write to the descriptor region (locked by default,
* until making the change below):
*/
deblobbedDescriptorStruct.masterAccessSection.flMstr1.fdRegionWriteAccess = 1;
/* relocate BIOS region and increase size to fill image */
deblobbedDescriptorStruct.regionSection.flReg1.BASE = 3; // 3<<FLREGIONBITSHIFT is 12KiB, which is where BIOS region is to begin (after descriptor and gbe)
deblobbedDescriptorStruct.regionSection.flReg1.LIMIT = ((factoryRomSize >> FLREGIONBITSHIFT) - 1);
/*
* ^ for example, 8MB ROM, that's 8388608 bytes.
* ^ 8388608>>FLREGIONBITSHIFT (or 8388608/4096) = 2048 bytes
* 2048 - 1 = 2047 bytes.
* This defines where the final 0x1000 (4KiB) page starts in the flash chip, because the hardware does:
* 2047<<FLREGIONBITSHIFT (or 2047*4096) = 8384512 bytes, or 7FF000 bytes
* (it can't be 0x7FFFFF because of limited number of bits)
*/
/* set ME region size to 0 - the ME is a blob, we don't want it in libreboot */
deblobbedDescriptorStruct.regionSection.flReg2.BASE = 0x1FFF; // setting 1FFF means setting size to 0. 1FFF<<FLREGIONBITSHIFT is outside of the ROM image (8MB) size?
/* ^ datasheet says to set this to 1FFF, but FFF was previously used and also worked. */
deblobbedDescriptorStruct.regionSection.flReg2.LIMIT = 0;
/*
* ^ 0<<FLREGIONBITSHIFT=0, so basically, the size is 0,
* ^ and the base (1FFF>>FLREGIONBITSHIFT) is well outside the higher 8MB range.
*/
/* relocate Gbe region to begin at 4KiB (immediately after the flash descriptor) */
deblobbedDescriptorStruct.regionSection.flReg3.BASE = 1; // 1<<FLREGIONBITSHIFT is 4096, which is where the Gbe region is to begin (after the descriptor)
deblobbedDescriptorStruct.regionSection.flReg3.LIMIT = 2;
/*
* ^ 2<<FLREGIONBITSHIFT=8192 bytes. So we are set it to size 8KiB after the first 4KiB in the flash chip.
*/
/* set Platform region size to 0 - another blob that we don't want */
deblobbedDescriptorStruct.regionSection.flReg4.BASE = 0x1FFF; // setting 1FFF means setting size to 0. 1FFF<<FLREGIONBITSHIFT is outside of the ROM image (8MB) size?
/* ^ datasheet says to set this to 1FFF, but FFF was previously used and also worked. */
deblobbedDescriptorStruct.regionSection.flReg4.LIMIT = 0;
/*
* ^ 0<<FLREGIONBITSHIFT=0, so basically, the size is 0,
* and the base (1FFF>>FLREGIONBITSHIFT) is well outside the higher 8MB range.
*/
/* disable ME in ICHSTRAP0 - the ME is a blob, we don't want it in libreboot */
deblobbedDescriptorStruct.ichStraps.ichStrap0.meDisable = 1;
/* disable ME and TPM in MCHSTRAP0 */
deblobbedDescriptorStruct.mchStraps.mchStrap0.meDisable = 1; // ME is a blob. not wanted in libreboot.
deblobbedDescriptorStruct.mchStraps.mchStrap0.tpmDisable = 1; // not wanted in libreboot
/*
* disable ME, apart from chipset bugfixes (ME region should first be re-enabled above)
* This is sort of like the CPU microcode updates, but for the chipset
* (commented out below here, since blobs go against libreboot's purpose,
* but may be interesting for others)
* deblobbedDescriptorStruct.mchStraps.mchStrap0.meAlternateDisable = 1;
*/
return deblobbedDescriptorStruct;
}
/*
* ---------------------------------------------------------------------
* Debugging functions:
* ---------------------------------------------------------------------
*/
/*
* show debugging info: descriptor region boundaries, in a 4KB struct.
*/
void printDescriptorRegionLocations(struct DESCRIPTORREGIONRECORD descriptorStruct, char* romName)
{
printf("\n");
/* Descriptor region */
printf(
"%s: Descriptor start block: %08x ; Descriptor end block: %08x\n",
romName,
descriptorStruct.regionSection.flReg0.BASE << FLREGIONBITSHIFT,
descriptorStruct.regionSection.flReg0.LIMIT << FLREGIONBITSHIFT
);
/* BIOS region */
printf(
"%s: BIOS start block: %08x ; BIOS end block: %08x\n",
romName,
descriptorStruct.regionSection.flReg1.BASE << FLREGIONBITSHIFT,
descriptorStruct.regionSection.flReg1.LIMIT << FLREGIONBITSHIFT
);
/* ME region */
printf(
"%s: ME start block: %08x ; ME end block: %08x\n",
romName,
descriptorStruct.regionSection.flReg2.BASE << FLREGIONBITSHIFT,
descriptorStruct.regionSection.flReg2.LIMIT << FLREGIONBITSHIFT
);
/* GBe region */
printf(
"%s: GBe start block: %08x ; GBe end block: %08x\n",
romName,
descriptorStruct.regionSection.flReg3.BASE << FLREGIONBITSHIFT,
descriptorStruct.regionSection.flReg3.LIMIT << FLREGIONBITSHIFT
);
/* Platform region */
printf(
"%s: Platform start block: %08x ; GBe end block: %08x\n",
romName,
descriptorStruct.regionSection.flReg4.BASE << FLREGIONBITSHIFT,
descriptorStruct.regionSection.flReg4.LIMIT << FLREGIONBITSHIFT
);
return;
}
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