The invention provides compounds having the general formula I:
and pharmaceutically acceptable salts thereof, wherein the variables R
A
, R
AA
, subscript n, ring A, X
2
, L, subscript m, X
1
, R
1
, R
2
, R
3
, R
4
, R
5
, and R
N
have the meaning as described herein, and compositions containing such compounds and methods for using such compounds and compactions.