ifdtool: Add validate option to ifdtool

Add an option to ifdtool which validates that the flash regions defined
in the descriptor match the coresponding areas in the FMAP.

BUG=chromium:992215
TEST=Ran 'ifdtool -t' with a good bios image and verify no issues
     run 'ifdtool -t' with a bad bios image and verify expected issues

Signed-off-by: Mathew King <mathewk@chromium.org>
Change-Id: Idebf105dee1b8f829d54bd65c82867af7aa4aded
Reviewed-on: https://review.coreboot.org/c/coreboot/+/34802
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

3 files changed, 139 insertions, 0 deletions

diff --git a/Documentation/ifdtool/binary_extraction.md b/Documentation/ifdtool/binary_extraction.md
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+# Intel IFD Binary Extraction Tutorial
+
+## Part 1: Extracting Binaries
+
+To begin extracting the binaries, first create a directory labeled "binaries"
+in the coreboot directory (i.e. /path/to/coreboot/binaries/).
+
+Now, execute the following commands to extract the binaries from a ROM image.
+**Note:** Make sure you are in the root coreboot directory.
+
+    cd /path/to/coreboot/util/ifdtool
+    ./ifdtool COREBOOT_IMAGE
+    ./ifdtool -d COREBOOT_IMAGE
+    ./ifdtool -x COREBOOT_IMAGE
+
+In the above steps, COREBOOT_IMAGE is the name of the ROM image to extract the
+binaries from, including the file path (ex. /build/coreboot.rom).
+
+Copy the extracted .bin files to the binaries directory you created previously.
+**Note:** You may want to rename your various .bin files to more clearly
+indicate what they are and their purpose.
+
+To extract the mrc.bin, move to the /coreboot/build directory and run the
+following command:
+
+    cd /path/to/coreboot/build/
+    ./cbfstool COREBOOT_IMAGE extract -n mrc.bin -f /path/to/destination/filename
+
+where COREBOOT_IMAGE is the filepath to the ROM image (same image as above),
+/path/to/destination is the filepath to the destination directory and filename
+is the output filename. An example command is given below:
+
+    ./cbfstool coreboot.rom extract -n mrc.bin -f /path/to/coreboot/binaries/mrc.bin
+
+## Part 2: Using extract_blobs.sh
+
+To simplify some of the steps above, there is a script in the
+/path/to/coreboot/util/chromeos/ directory called extract_blobs.sh what will
+extract the flashdescriptor.bin and intel_me.bin files.
+
+To run this script, switch to the /path/to/coreboot/util/chromeos/ directory
+and execute the script providing a coreboot image as an argument.
+
+    cd /path/to/coreboot/util/chromeos/
+    ./extract_blobs.sh COREBOOT_IMAGE
+
+Executing those commands will result in two binary blobs to appear in the
+/path/to/coreboot/util/chromeos/ directory under the names
+'flashdescriptor.bin' and 'me.bin'.
+
+## Part 3: Changing the coreboot configuration settings
+
+To begin using the binaries extracted above, enable the use of binary
+repositories in the menuconfig. From the main coreboot directory, run
+'make menuconfig'. Select "General Setup", then select "Allow use of
+binary-only repository", then exit to the main menu.
+
+To configure the ROM image for a specific board, select "Mainboard". Select
+"Mainboard vendor" and scroll to the correct vendor. Then select "Mainboard
+model" and select the name of the board model. Exit back to the main menu.
+
+To add the binaries you extracted, select "Chipset". Scroll and select "Add a
+System Agent Binary" and set the filepath to your mrc.bin file's filepath.
+Scroll and select "Add Intel descriptor.bin file" and type the filepath for
+your descriptor.bin file. Scroll down and select "Add Intel ME/TXE firmware
+file" and type the filepath for your ME file. Exit to the main menu.
+
+Select "Exit", and select "Yes" when prompted to save your configuration.
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diff --git a/Documentation/ifdtool/index.md b/Documentation/ifdtool/index.md
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+
+Contents:
+
+* [Intel IFD Binary Extraction](binary_extraction.md)
+* [IFD Layout](layout.md)
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diff --git a/Documentation/ifdtool/layout.md b/Documentation/ifdtool/layout.md
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+# IFD Layout
+
+A coreboot image for an Intel SoC contains two separate definitions of the
+layout of the flash. The Intel Flash Descriptor (IFD) which defines offsets and
+sizes of various regions of flash and the [coreboot FMAP](../lib/flashmap.md).
+
+The FMAP should define all of the of the regions defined by the IFD to ensure
+that those regions are accounted for by coreboot and will not be accidentally
+modified.
+
+## IFD mapping
+
+The names of the IFD regions in the FMAP should follow the convention of
+starting with the prefix `SI_` which stands for `silicon initialization` as a
+way to categorize anything required by the SoC but not provided by coreboot.
+
+|IFD Region index|IFD Region name|FMAP Name|Notes|
+|---|---|---|---|
+|0|Flash Descriptor|SI_DESC|Always the top 4KB of flash|
+|1|BIOS|SI_BIOS|This is the region that contains coreboot|
+|2|Intel ME|SI_ME||
+|3|Gigabit Ethernet|SI_GBE||
+|4|Platform Data|SI_PDR||
+|8|EC Firmware|SI_EC|Most Chrome OS devices do not use this region; EC firmware is stored BIOS region of flash|
+
+## Validation
+
+The ifdtool can be used to manipulate a firmware image with a IFD. This tool
+will not take into account the FMAP while modifying the image which can lead to
+unexpected and hard to debug issues with the firmware image. For example if the
+ME region is defined at 6 MB in the IFD but the FMAP only allocates 4 MB for the
+ME, then when the ME is added by the ifdtool 6 MB will be written which could
+overwrite 2 MB of the BIOS.
+
+In order to validate that the FMAP and the IFD are compatible the ifdtool
+provides --validate (-t) option. `ifdtool -t` will read both the IFD and the
+FMAP in the image and for every non empty region in the IFD if that region is
+defined in the FMAP but the offset or size is different then the tool will
+return an error.
+
+Example:
+
+```console
+foo@bar:~$ ifdtool -t bad_image.bin
+Region mismatch between bios and SI_BIOS
+ Descriptor region bios:
+  offset: 0x00400000
+  length: 0x01c00000
+ FMAP area SI_BIOS:
+  offset: 0x00800000
+  length: 0x01800000
+Region mismatch between me and SI_ME
+ Descriptor region me:
+  offset: 0x00103000
+  length: 0x002f9000
+ FMAP area SI_ME:
+  offset: 0x00103000
+  length: 0x006f9000
+Region mismatch between pd and SI_PDR
+ Descriptor region pd:
+  offset: 0x003fc000
+  length: 0x00004000
+ FMAP area SI_PDR:
+  offset: 0x007fc000
+  length: 0x00004000
+```
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