On: Segfaults are our friends and teachers

[dfox]

No. Typical C function looks something like this:

  push %rbp
  mov %rsp, %rbp
  sub $something, %rsp
  ... actual code ...
  mov %rbp, %rsp
  ret

The sub $something, %rsp instruction is everything that user-space does to allocate stack memory. Actual allocation of stack pages happens in kernel in a way that is completely transparent as long as the $something does not get unreasonably large.