FreeCalypso > hg > freecalypso-reveng

annotate se_k200i/flash-notes @ 393:6c31d8c54ae4

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
se_k200i: preliminary analysis
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 06 Nov 2022 01:13:43 +0000
parents
children 00f5287db832
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
393
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
1 SE K200 family phones have 16 MiB of flash total, physically presented to the
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
2 Calypso chip as two banks of 8 MiB each. Their official fw architecture uses
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
3 the following flash organization:
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
4
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
5 Flash bank 1, first 64 KiB sector:
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
6
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
7 This part of the flash naturally contains the boot entry point. The word at
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
8 0x2000 equals 1, telling Calypso boot ROM to move itself out of the way and
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
9 perform a watchdog reset, and then the reset entry point is at 0. The code
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
10 implemented by SE or their ODM in this flash sector is a boot stage of their
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
11 own invention, eventually passing control to the main fw entry point at
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
12 0x200000.
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
13
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
14 Flash bank 1, 64 KiB sector at 0x10000:
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
15
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
16 This sector holds two items of factory-programmed data, apparently intended to
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
17 remain immutable for the lifetime of each hw unit:
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
18
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
19 7 bytes at 0x10000: the phone's IMEI, format obvious, no obfuscation
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
20 1 byte at 0x10007: 0xFF filler
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
21 64 bytes at 0x10008: appear to be cryptographically random filler
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
22
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
23 Flash bank 1 starting at 0x20000:
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
24
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
25 The main firmware image resides here, entry point right at 0x200000.
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
26
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
27 Flash bank 2, first 13 sectors of 256 KiB each:
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
28
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
29 The firmware on this phone model uses classic TIFFS. Their TIFFS organization
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
30 is 256x13 (a little smaller than Pirelli's 256x18), sitting at the beginning of
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
31 flash bank 2, mapped into Calypso address space at 0x01800000. FFS design
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
32 appears to be self-regenerating: if the fw is booted with all FFS sectors
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
33 erased, it will not only format a new FFS like Pirelli's fw, but also fill it
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
34 with all necessary data. In contrast with Pirelli's fw architecture, the FFS
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
35 in these SE K200 phones appears to NOT contain any static asset files that must
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
36 be loaded externally.
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
37
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
38 Flash bank 2, area starting at 0x01B40000, right after TIFFS:
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
39
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
40 This area appears to be an extension of the firmware. Without a lot more
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
41 reverse eng work, it is not obvious if this area contains any executable code,
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
42 or if it is only data bits like UI pixel images, MIDI ringtones, language
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
43 strings etc.
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
44
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
45 Flash bank 2, 64 KiB sector at 0x01FD0000:
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
46
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
47 This sector holds factory calibration data, including RF, AFC (VCXO) and MADC
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
48 calibrations. When the firmware reinitializes a freshly formatted FFS, it must
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
49 be copying calibration bits from this sector.
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
50
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
51 Flash bank 2, 64 KiB sector at 0x01FF0000 (end of flash):
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
52
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
53 First 0x2C8 bytes: purpose unknown, but they are fed into the hash function
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
54 that determines whether or not the firmware is allowed to boot.
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
55
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
56 8 bytes at 0x01FF02C8: output of some kind of cryptographic hash function
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
57
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
58 There is a hash function implemented in the custom bootloader in sector 0 (not
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
59 studied in detail) whose inputs are the IMEI record at 0x10000, the block of
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
60 0x2C8 bytes at 0x01FF0000 and the block of 64 bytes at 0x10008 in this order.
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
61 The output must match the 8 bytes at 0x01FF02C8, or the code refuses to boot
6c31d8c54ae4 se_k200i: preliminary analysis
Mychaela Falconia <falcon@freecalypso.org>
parents:
diff changeset
62 and goes into a dead hang instead.