GDB: Listing all mapped memory regions for a crashed process

In GDB 7.2:

(gdb) help info proc
Show /proc process information about any running process.
Specify any process id, or use the program being debugged by default.
Specify any of the following keywords for detailed info:
  mappings -- list of mapped memory regions.
  stat     -- list a bunch of random process info.
  status   -- list a different bunch of random process info.
  all      -- list all available /proc info.

You want info proc mappings, except it doesn’t work when there is no /proc (such as during pos-mortem debugging).

Try maintenance info sections instead.