phi gcc <phi.gcc@xxxxxxxxx> writes: > I see prolog like this in some linux kernel functions > > 0xffffffff8102fba0 pushq %rbp > 0xffffffff8102fba1 movq %rsp,%rbp > 0xffffffff8102fba4 nopl 0x0(%rax,%rax,1) <== > 0xffffffff8102fba9 movl %edi,%edi <== > 0xffffffff8102fbab movl %esi,-0xa05000(%rdi) Which function is that? The NOPs may be part of a scheme where Linux modifies itself at run time. See arch/x86/kernel/alternative.c and Documentation/static-keys.txt, for two such schemes. Do you see similar NOPs in non-Linux code?