On Mon, Nov 11, 2019 at 4:03 PM Florian Weimer <fweimer@xxxxxxxxxx> wrote: > > * Michael Kerrisk: > > > Another difference for the raw clone() system call is that the > > stack argument may be NULL, in which case the child uses a dupli‐ > > cate of the parent's stack. (Copy-on-write semantics ensure that > > the child gets separate copies of stack pages when either process > > modifies the stack.) In this case, for correct operation, the > > CLONE_VM option should not be specified. (If the child shares the > > parent's memory because of the use of the CLONE_VM flag, then no > > copy-on-write duplication occurs and chaos is likely to result.) > > I think sharing the stack also works with CLONE_VFORK with CLONE_VM, as > long as measures are taken to preserve the return address in a register. That basically just requires that the userspace function declaration for clone3 includes __attribute__((returns_twice)), right?
