2005-11-04 Frank Ch. Eigler <fche@redhat.com>

	* tapsets.cxx (dwarf_derived_probe::emit_registrations): Add
	possible kprobe address prechecking logic.  Set kretprobes
	maxactive to zero.
	* translate.cxx (emit_module_init): Set a more helpful default
	probe_point value for use in registration errors.  Exit properly
	after registration failure of probe #0.

3 files changed, 31 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 46621e75..490c14ea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2005-11-04  Frank Ch. Eigler  <fche@redhat.com>
+
+	* tapsets.cxx (dwarf_derived_probe::emit_registrations): Add
+	possible kprobe address prechecking logic.  Set kretprobes
+	maxactive to zero.
+	* translate.cxx (emit_module_init): Set a more helpful default
+	probe_point value for use in registration errors.  Exit properly
+	after registration failure of probe #0.
+
 2005-11-04  Roland McGrath  <roland@redhat.com>
 
 	* tapsets.cxx (add_probe_point): Use dwfl_module_relocation_info to
diff --git a/tapsets.cxx b/tapsets.cxx
index 8345c797..0e4357e7 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -2601,14 +2601,25 @@ dwarf_derived_probe::emit_registrations (translator_output* o,
   o->indent(1);
   string probe_name = struct_kprobe_array_name(probenum) + "[i]";
 
+#if 0
+  // XXX: triggers false negatives on RHEL4U2 kernel
+  // emit address verification code
+  o->newline() << "void *addr = " << probe_name;
+  if (has_return)
+    o->line() << ".kp.addr;";
+  else
+    o->line() << ".addr;";
+  o->newline() << "rc = ! virt_addr_valid (addr);";
+#endif
+
   if (has_return)
     {
       o->newline() << "#ifdef ARCH_SUPPORTS_KRETPROBES";
       o->newline() << probe_name << ".handler = &" << func_name << ";";
-      o->newline() << probe_name << ".maxactive = 1;";
+      o->newline() << probe_name << ".maxactive = 0;"; // request default
       // XXX: pending PR 1289
       // o->newline() << probe_name << ".kp_fault_handler = &stap_kprobe_fault_handler;";
-      o->newline() << "rc = register_kretprobe (&(" << probe_name << "));";
+      o->newline() << "rc = rc || register_kretprobe (&(" << probe_name << "));";
       o->newline() << "#else";
       o->newline() << "rc = 1;";
       o->newline() << "#endif";
@@ -2618,7 +2629,7 @@ dwarf_derived_probe::emit_registrations (translator_output* o,
       o->newline() << probe_name << ".pre_handler = &" << func_name << ";";
       // XXX: pending PR 1289
       // o->newline() << probe_name << ".kp_fault_handler = &stap_kprobe_fault_handler;";
-      o->newline() << "rc = register_kprobe (&(" << probe_name << "));";
+      o->newline() << "rc = rc || register_kprobe (&(" << probe_name << "));";
     }
 
   o->newline() << "if (unlikely (rc)) {";
diff --git a/translate.cxx b/translate.cxx
index bdacdcca..0c1ce84f 100644
--- a/translate.cxx
+++ b/translate.cxx
@@ -825,9 +825,13 @@ c_unparser::emit_module_init ()
     {
       o->newline() << "/* register probe #" << i << ", ";
       o->line() << session->probes[i]->locations.size() << " location(s) */";
-      // default
+
+      // By default, mark the first location as the site of possible
+      // registration failure.  This is helpful since non-dwarf
+      // derived_probes tend to have only a single location.
+      assert (session->probes[i]->locations.size() > 0);
       o->newline() << "probe_point = " <<
-        lex_cast_qstring (*session->probes[i]->tok) << ";";
+        lex_cast_qstring (*session->probes[i]->locations[0]) << ";";
       session->probes[i]->emit_registrations (o, i);
 
       o->newline() << "if (unlikely (rc)) {";
@@ -843,6 +847,8 @@ c_unparser::emit_module_init ()
       // essential for kprobes.
       if (i > 0)
         o->newline() << "goto unregister_" << (i-1) << ";";
+      else
+        o->newline() << "goto out;";
 
       o->newline(-1) << "}";
     }