Raised beds are what many people do on rocky ground as it saves heaps of time and backache digging into the rock.
Making your own soil can be done either totally from scratch or by adding to and enriching low-quality cheap dirt. The latter being the fastest and easiest and possibly the best because improving dirt with organic matter like compost, mulch and manures etc has the advantage of fill already there to begin with and minerals for the plants to access.
Obviously, the dirt can be poor quality (such as too fine or too heavy or too much rock) but it can't be toxic or anything...
Adding organic matter to the soil will improve it over time and transform the medium into a rich soil that is free draining but also holds enough water and has lots of nutrients - that's what plants love.