+
+ lck_mtx_unlock(&dtrace_meta_lock);
+}
+
+/**
+ * DTrace Process functions
+ */
+
+void
+dtrace_proc_fork(proc_t *parent_proc, proc_t *child_proc, int spawn)
+{
+ /*
+ * This code applies to new processes who are copying the task
+ * and thread state and address spaces of their parent process.
+ */
+ if (!spawn) {
+ /*
+ * APPLE NOTE: Solaris does a sprlock() and drops the
+ * proc_lock here. We're cheating a bit and only taking
+ * the p_dtrace_sprlock lock. A full sprlock would
+ * task_suspend the parent.
+ */
+ dtrace_sprlock(parent_proc);
+
+ /*
+ * Remove all DTrace tracepoints from the child process. We
+ * need to do this _before_ duplicating USDT providers since
+ * any associated probes may be immediately enabled.
+ */
+ if (parent_proc->p_dtrace_count > 0) {
+ dtrace_fasttrap_fork(parent_proc, child_proc);
+ }
+
+ dtrace_sprunlock(parent_proc);
+
+ /*
+ * Duplicate any lazy dof(s). This must be done while NOT
+ * holding the parent sprlock! Lock ordering is
+ * dtrace_dof_mode_lock, then sprlock. It is imperative we
+ * always call dtrace_lazy_dofs_duplicate, rather than null
+ * check and call if !NULL. If we NULL test, during lazy dof
+ * faulting we can race with the faulting code and proceed
+ * from here to beyond the helpers copy. The lazy dof
+ * faulting will then fail to copy the helpers to the child
+ * process. We return if we duplicated lazy dofs as a process
+ * can only have one at the same time to avoid a race between
+ * a dtrace client and dtrace_proc_fork where a process would
+ * end up with both lazy dofs and helpers.
+ */
+ if (dtrace_lazy_dofs_duplicate(parent_proc, child_proc) == DTRACE_LAZY_DOFS_DUPLICATED) {
+ return;
+ }
+
+ /*
+ * Duplicate any helper actions and providers if they haven't
+ * already.
+ */
+#if !defined(__APPLE__)
+ /*
+ * The SFORKING
+ * we set above informs the code to enable USDT probes that
+ * sprlock() may fail because the child is being forked.
+ */
+#endif
+ /*
+ * APPLE NOTE: As best I can tell, Apple's sprlock() equivalent
+ * never fails to find the child. We do not set SFORKING.
+ */
+ if (parent_proc->p_dtrace_helpers != NULL && dtrace_helpers_fork) {
+ (*dtrace_helpers_fork)(parent_proc, child_proc);
+ }
+ }
+}
+
+void
+dtrace_proc_exec(proc_t *p)
+{
+ /*
+ * Invalidate any predicate evaluation already cached for this thread by DTrace.
+ * That's because we've just stored to p_comm and DTrace refers to that when it
+ * evaluates the "execname" special variable. uid and gid may have changed as well.
+ */
+ dtrace_set_thread_predcache(current_thread(), 0);
+
+ /*
+ * Free any outstanding lazy dof entries. It is imperative we
+ * always call dtrace_lazy_dofs_destroy, rather than null check
+ * and call if !NULL. If we NULL test, during lazy dof faulting
+ * we can race with the faulting code and proceed from here to
+ * beyond the helpers cleanup. The lazy dof faulting will then
+ * install new helpers which no longer belong to this process!
+ */
+ dtrace_lazy_dofs_destroy(p);
+
+
+ /*
+ * Clean up any DTrace helpers for the process.
+ */
+ if (p->p_dtrace_helpers != NULL && dtrace_helpers_cleanup) {
+ (*dtrace_helpers_cleanup)(p);
+ }
+
+ /*
+ * Cleanup the DTrace provider associated with this process.
+ */
+ proc_lock(p);
+ if (p->p_dtrace_probes && dtrace_fasttrap_exec_ptr) {
+ (*dtrace_fasttrap_exec_ptr)(p);
+ }
+ proc_unlock(p);
+}
+
+void
+dtrace_proc_exit(proc_t *p)
+{
+ /*
+ * Free any outstanding lazy dof entries. It is imperative we
+ * always call dtrace_lazy_dofs_destroy, rather than null check
+ * and call if !NULL. If we NULL test, during lazy dof faulting
+ * we can race with the faulting code and proceed from here to
+ * beyond the helpers cleanup. The lazy dof faulting will then
+ * install new helpers which will never be cleaned up, and leak.
+ */
+ dtrace_lazy_dofs_destroy(p);
+
+ /*
+ * Clean up any DTrace helper actions or probes for the process.
+ */
+ if (p->p_dtrace_helpers != NULL) {
+ (*dtrace_helpers_cleanup)(p);
+ }
+
+ /*
+ * Clean up any DTrace probes associated with this process.
+ */
+ /*
+ * APPLE NOTE: We release ptss pages/entries in dtrace_fasttrap_exit_ptr(),
+ * call this after dtrace_helpers_cleanup()
+ */
+ proc_lock(p);
+ if (p->p_dtrace_probes && dtrace_fasttrap_exit_ptr) {
+ (*dtrace_fasttrap_exit_ptr)(p);
+ }
+ proc_unlock(p);
projects / apple / xnu.git / blobdiff