Self modifying code always segmentation faults on Linux

Question

i found an article about self modifying code and tried to do some examples, but i get always segmentation faults. As fas as i can understand, there is a violation in memory

Answer 1

You should to change memory access permissions in runtime.

#include 

void *addr  = get_address_of_instruction_pointer();
int  length = 4096;   /* size of a page */

if (mprotect(addr, length, PROT_READ | PROT_WRITE | PROT_EXEC) == 0) {
    /* current code page is now writable and code from it is allowed for execution */
}