USERSPACE_TESTING.md

Userspace Testing

The main development happens in core directory. To start, cd into core.

Build

make configure # Do it once

make build

Install

make install

Basic Usage

# Run ePass on the program
epass read prog.o

# Run ePass on the program with gopt and popt
epass read --popt popts --gopt gopts prog.o

# Print the BPF program
epass print prog.o

For gopt and popt, see ePass Options.

Use ePass with libbpf

We may want to load a ePass-modified program to the kernel to see its effect. ePass provides a modified libbpf that allows users to run ePass before loading programs to the kernel. The advantage is that you do not need to change the kernel. However, running ePass in userspace cannot leverage the verifier, so it cannot use verifier information, cannot run verifier dependent passes, and cannot run kernel passes.

First, initializing all submodules.

git submodule update --init --recursive

Now open the libbpf source code directory and build:

cd third-party/ePass-libbpf/src
make -j

To install ePass libbpf, install:

sudo make install

After installing ePass libbpf, you could run any programs that depends on the libbpf shared library with ePass commands.

For bpftool, you need to build bpftool because by default it statically link libbpf.

An example of using ePass to load test.o eBPF program using bpftool:

sudo LIBBPF_ENABLE_EPASS=1 LIBBPF_EPASS_GOPT="verbose=3" LIBBPF_EPASS_POPT="msan" bpftool prog load test.o /sys/fs/bpf/test