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 20.04 environment. The preferred way is using a chroot. To get started, install debootstrap and schroot. If you're running a Debian-based distro, run:

sudo apt install debootstrap schroot

Create a configuration for a Focal chroot:

sudo $EDITOR /etc/schroot/chroot.d/focal_amd64.conf

Add the following to the new file, replacing the instances of thomasanderson with your own username.

[focal_amd64]
description=Ubuntu 20.04 Focal for amd64
directory=/srv/chroot/focal_amd64
personality=linux
root-users=thomasanderson
type=directory
users=thomasanderson

Bootstrap the chroot:

sudo mkdir -p /srv/chroot/focal_amd64
sudo debootstrap --variant=buildd --arch=amd64 focal /srv/chroot/focal_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.

sudo mount --bind "$HOME" /home

Add sources.list:

sudo $EDITOR /srv/chroot/focal_amd64/etc/apt/sources.list

Add the following contents to the file:

deb     http://archive.ubuntu.com/ubuntu/ focal          main restricted universe
deb-src	http://archive.ubuntu.com/ubuntu/ focal          main restricted universe
deb     http://archive.ubuntu.com/ubuntu/ focal-security main restricted universe
deb-src http://archive.ubuntu.com/ubuntu/ focal-security main restricted universe
deb     http://archive.ubuntu.com/ubuntu/ focal-updates  main restricted universe
deb-src http://archive.ubuntu.com/ubuntu/ focal-updates  main restricted universe

Enter the chroot and install the necessary packages:

schroot -c focal_amd64 -u root --directory /home/dev/chromium/src
apt update
apt install lsb-release sudo python pkg-config libgtk2.0-bin libdrm-dev nih-dbus-tool help2man

Install library packages:

third_party/instrumented_libraries/scripts/install-build-deps.sh

Change to a non-root user:

exit
schroot -c focal_amd64 -u `whoami` --directory /home/dev/chromium/src

Add depot_tools to your PATH. For example, I have it in ~/dev/depot_tools, so I use:

export PATH=/home/dev/depot_tools/:$PATH

Now we're ready to build the libraries. A clean build takes a little over 8 minutes on a 72-thread machine.

third_party/instrumented_libraries/scripts/build_and_package.py --parallel -j $(nproc) all focal

Uploading the libraries

This requires write permission on the chromium-instrumented-libraries GCS bucket. dpranke@ can grant access.

# Exit the chroot.
exit

# 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*.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