If you want to construct a program which disables ASLR for itself when it runs, you can use the personality system call on Linux. Here's a recipe:
#include <stdio.h>#include <sys/personality.h>int main(int argc, char **argv) { const int old_personality = personality(ADDR_NO_RANDOMIZE); if (!(old_personality & ADDR_NO_RANDOMIZE)) { const int new_personality = personality(ADDR_NO_RANDOMIZE); if (new_personality & ADDR_NO_RANDOMIZE) { execv(argv[0], argv); } } printf("&argc == %p\n", (void *) &argc);}If you look at the source for setarch, it calls personality twice in roughly this pattern. The major difference is that setarch calls exec on some other program, whereas my recipe execs itself. It's important that you use non-zero-ness of & ADDR_NO_RANDOMIZE and not equality tests: else you can go into an infinite exec loop if you e.g. compile with -z execstack.
See also the man page for personality.