Willis is listed as questionable on the team's injury report for Sunday's NFC Championship Game against the New York Giants.
Ginn and Goodwin were injured during last weekend's divisional playoff victory over the New Orleans Saints.
Walker broke his left jaw in two places late in the regular season and hopes to play against the Giants. He had the wires removed Monday and has been a limited participant in practice since Wednesday.
Walker had his best game of the season against the Giants in November, catching six passes for 69 yards in a 27-20 victory.
More rain is in the forecast in the Bay Area, and the 49ers pulled out the cold-weather clothing before working out in windy, chilly conditions Friday.
Harbaugh expects the field at Candlestick Park to be in good shape considering the grass was replaced before the Monday Night game Dec. 19.
The Associated Press contributed to this report.