Function sim_fork

arch/sim/src/sim/sim_fork.c:91–179

nosanitize_address
#endif
pid_t sim_fork(const xcpt_reg_t *context)
{
  struct tcb_s *parent = this_task();
  struct tcb_s *child;
  unsigned char *pout;
  unsigned char *pin;
  xcpt_reg_t newsp;
  xcpt_reg_t newfp;
  xcpt_reg_t newtop;
  xcpt_reg_t stacktop;
  xcpt_reg_t stackutil;

  sinfo("fork context [%p]:\n", context);
  sinfo("  frame pointer:%zx sp:%zx pc:%zx\n",
        context[JB_FP], context[JB_SP], context[JB_PC]);

  /* Allocate and initialize a TCB for the child task. */

  child = nxtask_setup_fork((start_t)context[JB_PC]);
  if (!child)
    {
      serr("ERROR: nxtask_setup_fork failed\n");
      return (pid_t)ERROR;
    }

  sinfo("TCBs: Parent=%p Child=%p\n", parent, child);

  /* How much of the parent's stack was utilized?  The ARM uses
   * a push-down stack so that the current stack pointer should
   * be lower than the initial, adjusted stack pointer.  The
   * stack usage should be the difference between those two.
   */

  stacktop = (xcpt_reg_t)parent->stack_base_ptr +
                         parent->adj_stack_size;
  DEBUGASSERT(stacktop > context[JB_SP]);
  stackutil = stacktop - context[JB_SP];

  sinfo("Parent: stackutil:%zu\n", stackutil);

  /* Make some feeble effort to preserve the stack contents.  This is
   * feeble because the stack surely contains invalid pointers and other
   * content that will not work in the child context.  However, if the
   * user follows all of the caveats of fork() usage, even this feeble
   * effort is overkill.
   */

  newtop = (xcpt_reg_t)child->stack_base_ptr +
                       child->adj_stack_size;
  newsp = newtop - stackutil;
  pout = (unsigned char *)newsp;
  pin  = (unsigned char *)context[JB_SP];
  while (stackutil-- > 0) *pout++ = *pin++;

  /* Was there a frame pointer in place before? */

  if (context[JB_FP] >= context[JB_SP] && context[JB_FP] < stacktop)
    {