Place the pork loin on a baking sheet, drizzle with oil, sprinkle with salt and pepper, and roast according to the package instructions.
While your pork is in the oven, prepare the blackberry sauce. Place the sauce ingredients in a medium saucepan and place on the stove over medium heat. Continue to heat (and stir occasionally) until the blackberries break down into a slightly thickened sauce. Remove the cinnamon stick and discard.