open(), fork() or read(); this is because these functions are simply wrappers around the syscalls, making it much easier for the programmer.int80 instruction. Once it's called, the kernel checks the value stored in RAX - this is the syscall number, which defines what syscall gets run. As per the table, the other parameters can be stored in RDI, RSI, RDX, etc and every parameter has a different meaning for the different syscalls.execve syscall, which executes the program passed to it in RDI. RSI and RDX hold arvp and envp respectively.system() function, we can use execve to call /bin/sh instead - all we have to do is pass in a pointer to /bin/sh to RDI, and populate RSI and RDX with 0 (this is because both argv and envp need to be NULL to pop a shell).