set the IP in return probes to the returned-to instruction

It's easily available in kretprobes and uretprobes and is consistent
with the rest of the program state.

* translate.cxx (emit_common_header) : add uretprobe_instance to context.
* tapsets.cxx (common_probe_entryfn_prologue): Initialize ri in
  context to 0.
  (dwarf_derived_probe_group::emit_module_decls): Change IP to return
  address in kretprobes.
  (uprobe_derived_probe_group::emit_module_decls): enter_uretprobe_probe:
  set ri (uretprobe_instance) in context. Change IP to return
  address in uretprobes. Don't emit uprobe include and #define
* runtime/runtime.h : Add includes and #define for uprobes.
* runtime/stack.c (_stp_stack_print, _stp_stack_snprint): Add extra
  argument for uretprobe_instance.
* tapset/context-unwind.stp (print_backtrace, backtrace): Pass NULL
  for uretprobe_instance to _stp_stack_print.
* tapset/ucontext-unwind.stp (print_ubacktrace, ubacktrace): pass
  uretprobe_instance to _stp_stack_print
* testsuite/systemtap.context/uprobe_uaddr.exp : new test for uaddr in
  function probes
* testsuite/systemtap.context/uprobe_uaddr.stp : new file

1 files changed, 24 insertions, 0 deletions

diff --git a/testsuite/systemtap.context/uprobe_uaddr.stp b/testsuite/systemtap.context/uprobe_uaddr.stp
new file mode 100644
index 00000000..1528e559
--- /dev/null
+++ b/testsuite/systemtap.context/uprobe_uaddr.stp
@@ -0,0 +1,24 @@
+probe process("uprobe_uaddr").function("main").call {
+    println(usymdata(uaddr()))
+}
+
+probe process("uprobe_uaddr").function("main").return {
+    println(usymdata(uaddr()))
+}
+
+probe process("uprobe_uaddr").function("func").call {
+    println(usymdata(uaddr()))
+}
+
+probe process("uprobe_uaddr").function("func").return {
+    println(usymdata(uaddr()))
+}
+
+probe process("uprobe_uaddr").function("func2").call {
+    println(usymdata(uaddr()))
+}
+
+probe process("uprobe_uaddr").function("func2").return {
+    println(usymdata(uaddr()))
+}
+