Add docs/linux_instrumented_libraries.md

R=thestig
BUG=None

Change-Id: I4be3f08565992d08a6ab4e7b06552efa8d77c23e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1974582
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726467}

docs/linux_dependencies.md

@@ -193,5 +193,6 @@ the instrumented libraries. To do this, add the library dev package to
 Then add `:libdbus-1-3` to
 `//third_party/instrumented_libraries:locally_built`'s `deps`.
 
-TODO(thomasanderson): Add doc to explain how to build and upload instrumented
-libraries.
+See [Linux Instrumented
+Libraries](https://chromium.googlesource.com/chromium/src.git/+/master/docs/linux_instrumented_libraries.md)
+for instructions on building and uploading the instrumented libraries.

docs/linux_instrumented_libraries.md

+# Linux Instrumented Libraries
+
+The instrumented libraries are a collection of Chromium's dependencies built
+with *SAN enabled. The MSAN libraries are required for an MSAN build to run. The
+others are optional, and are currently unused.
+
+## Building the instrumented libraries
+
+### Setting up a chroot
+
+Building the libraries requires `apt-get source`, so the build must be done from
+an Ubuntu 14.04 environment. The preferred way is using a chroot. To get
+started, install `debootstrap` and `schroot`. If you're running a Debian-based
+distro, run:
+
+```shell
+sudo apt install debootstrap schroot
+```
+
+Create a configuration for a Trusty chroot:
+
+```shell
+sudo $EDITOR /etc/schroot/chroot.d/trusty_amd64.conf
+```
+
+Add the following to the new file, replacing the instances of `thomasanderson`
+with your own username.
+
+```
+[trusty_amd64]
+description=Ubuntu 14.04 Trusty for amd64
+directory=/srv/chroot/trusty_amd64
+personality=linux
+root-users=thomasanderson
+type=directory
+users=thomasanderson
+```
+
+Bootstrap the chroot:
+
+```shell
+sudo mkdir -p /srv/chroot/trusty_amd64
+sudo debootstrap --variant=buildd --arch=amd64 trusty /srv/chroot/trusty_amd64 http://archive.ubuntu.com/ubuntu/
+```
+
+If your `$HOME` directory is not `/home` (as is the case on gLinux), then route
+`/home` to the real thing. `schroot` automatically mounts `/home`, which is
+where I'm assuming you keep your source tree and `depot_tools`.
+
+```shell
+sudo mount --bind "$HOME" /home
+```
+
+Add `sources.list`:
+
+```shell
+sudo $EDITOR /srv/chroot/trusty_amd64/etc/apt/sources.list
+```
+
+Add the following contents to the file:
+
+```
+deb     http://archive.ubuntu.com/ubuntu/ trusty          main restricted universe
+deb-src	http://archive.ubuntu.com/ubuntu/ trusty          main restricted universe
+deb     http://archive.ubuntu.com/ubuntu/ trusty-security main restricted universe
+deb-src http://archive.ubuntu.com/ubuntu/ trusty-security main restricted universe
+deb     http://archive.ubuntu.com/ubuntu/ trusty-updates  main restricted universe
+deb-src http://archive.ubuntu.com/ubuntu/ trusty-updates  main restricted universe
+```
+
+Enter the chroot and install the necessary packages:
+
+```shell
+schroot -c trusty_amd64 -u root --directory /
+apt update
+apt install lsb-release sudo python pkg-config libgtk2.0-bin libdrm-dev nih-dbus-tool help2man
+```
+
+Add `depot_tools` to your `PATH`. For example, I have it in `~/dev/depot_tools`,
+so I use:
+
+```shell
+export PATH=/home/thomasanderson/dev/depot_tools/:$PATH
+```
+
+Change to your src directory:
+
+```shell
+cd /home/thomasanderson/dev/chromium/src
+```
+
+Install library packages:
+
+```shell
+third_party/instrumented_libraries/scripts/install-build-deps.sh
+```
+
+Now we're ready to build the libraries. A clean build takes a little over 8
+minutes on a 72-thread machine.
+
+```shell
+third_party/instrumented_libraries/scripts/build_and_package.py --parallel -j $(nproc) all
+```
+
+## Uploading the libraries
+
+This requires write permission on the `chromium-instrumented-libraries` GCS
+bucket. `dpranke@` can grant access.
+
+```shell
+# Exit the chroot.
+exit
+
+# Fix permissions.
+sudo chown -R `whoami`:`groups | awk '{print $1;}'` *.tgz out/Instrumented-*
+
+# Move files into place.
+mv *.tgz third_party/instrumented_libraries/binaries
+
+# Upload.
+upload_to_google_storage.py -b chromium-instrumented-libraries third_party/instrumented_libraries/binaries/msan-chained-origins-trusty.tgz
+upload_to_google_storage.py -b chromium-instrumented-libraries third_party/instrumented_libraries/binaries/msan-no-origins-trusty.tgz
+```
+
+## Testing and uploading a CL
+
+After uploading, run `gclient sync` and test out a build with `is_msan = true`
+in your `args.gn`. Try running eg. `chrome` and `unit_tests` to make sure it's
+working. The binaries should work natively on gLinux.
+
+When uploading a CL, make sure to add the following in the description so that
+the MSAN bot will run on the CQ:
+
+```
+CQ_INCLUDE_TRYBOTS=luci.chromium.try:linux_chromium_msan_rel_ng
+```