PR11151: Recover stap_uprobes slots on process exit

When a process exits, it won't necessarily bother to munmap all of its
shared libraries.  This patch makes sure that with uprobes in libraries,
we still grab an exit notification and clear everything out.

* runtime/uprobes-common.c (stap_uprobe_process_munmap): New.
* tapsets.cxx (uprobe_derived_probe_group::emit_module_decls): Use above
  callback so that we can recover our resources on process exit.

1 files changed, 15 insertions, 0 deletions

diff --git a/runtime/uprobes-common.c b/runtime/uprobes-common.c
index b0273ba4..58e3a05f 100644
--- a/runtime/uprobes-common.c
+++ b/runtime/uprobes-common.c
@@ -286,4 +286,19 @@ static int stap_uprobe_munmap_found (struct stap_task_finder_target *tgt, struct
   return stap_uprobe_change_minus (tsk, addr, length, stf);
 }
 
+/* The task_finder_callback we use for ET_DYN targets.
+   This just forces an unmap of everything as the process exits.
+   (PR11151) */
+static int stap_uprobe_process_munmap (struct stap_task_finder_target *tgt, struct task_struct *tsk, int register_p, int process_p) {
+  const struct stap_uprobe_tf *stf = container_of(tgt, struct stap_uprobe_tf, finder);
+  if (! process_p) return 0; /* ignore threads */
+  #ifdef DEBUG_TASK_FINDER_VMA
+  _stp_dbug (__FUNCTION__,__LINE__, "%cproc pid %d stf %p %p path %s\n", register_p?'+':'-', tsk->tgid, tgt, stf, stf->pathname);
+  #endif
+  /* Covering 0->TASK_SIZE means "unmap everything" */
+  if (!register_p)
+    return stap_uprobe_change_minus (tsk, 0, TASK_SIZE, stf);
+  return 0;
+}
+
 #endif /* _UPROBE_COMMON_C_ */