copyin and copyinstr Subroutines

DTrace's interaction with processes is a little different than most traditional debuggers or observability tools. Many such tools appear to execute within the scope of the process, letting users dereference pointers to program variables directly. Rather than appearing to execute within or as part of the process itself, DTrace probes execute in the Oracle Solaris kernel. To access process data, a probe needs to use the copyin or copyinstr subroutines to copy user process data into the address space of the kernel.