summaryrefslogtreecommitdiffstats
path: root/resources/utilities/ich9deblob/descriptor/descriptor.c
blob: aa3d84e59e172d0703f0f62cd2ad64e3ce4cb3c6 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
/*
 *  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;
}