https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63245
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I think it shows some bytes also before and after the region. Perhaps it can do that with the exception when there is a page boundary in the region before the access or after it, or perhaps it can do so without extra overhead in that case, otherwise look at /proc/self/maps to see if it can access those bytes, or use mincore syscall first, etc.
