meta-arm/meta-arm-gcs

Guarded Control Stack prototype
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To build:

First, install Kas if you don't already have it:

$ pip3 install --user kas

Then use Kas to build an image:

$ kas build --update gcs.yml

To run the image inside an FVP:

$ kas shell gcs.yml -c "../../scripts/runfvp --console"

To run the tests automatically, Kas can be used:

$ kas build --update meta-arm-gcs/gcs-test.yml

Verification:

On boot, the kernel should detect that the cores have GCS:

CPU features: detected: Guarded Control Stack (GCS)

Binaries should be tagged with PAC/BTI/GCS:

$ readelf -n /bin/bash | grep AArch
Properties: AArch64 feature: BTI, PAC, GCS

Enabling GCS tunables shouldn't cause crashes:

$ GLIBC_TUNABLES=glibc.cpu.aarch64_gcs=1:glibc.cpu.aarch64_gcs_policy=2 ls /
bin boot dev etc home lib lost+found media mnt proc run sbin sys tmp usr var