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

2 files changed, 82 insertions, 0 deletions

diff --git a/testsuite/systemtap.context/uprobe_uaddr.exp b/testsuite/systemtap.context/uprobe_uaddr.exp
new file mode 100644
index 00000000..521dfa57
--- /dev/null
+++ b/testsuite/systemtap.context/uprobe_uaddr.exp
@@ -0,0 +1,58 @@
+# Tests uaddr in function call and return probes. For a call probe we
+# expect the address to be in the function; for a return probe it
+# should be in the function's caller.
+
+set test "uprobe_uaddr"
+
+# Only run on make installcheck and utrace present.
+if {! [installtest_p]} { untested "$test"; return }
+if {! [utrace_p]} { untested "$test"; return }
+
+set testpath  "$srcdir/$subdir"
+set testsrc   "$testpath/uprobe_stmt_num.c"
+set testexe   "[pwd]/$test"
+
+# We want debug info and no optimization (every line counts).
+set testflags "additional_flags=-g additional_flags=-O0"
+set teststp   "$testpath/$test.stp"
+
+set res [target_compile $testsrc $testexe executable $testflags]
+if { $res != "" } {
+    verbose "target_compile failed: $res" 2
+    fail "unable to compile $testsrc"
+    return
+}
+
+set cmd [concat stap -c $testexe $teststp]
+send_log "cmd: $cmd\n"
+catch {eval exec $cmd} output
+send_log "cmd output:\n $output\n"
+
+set output_lines [split $output "\n"]
+
+set lines [llength $output_lines]
+if { $lines == 6 } {
+    pass "$test"
+} else {
+    fail "$test ($lines)"
+}
+
+set result_funcs [list "main *" "func *" "func2 *" "func *" "main *"]
+
+foreach expected $result_funcs output $output_lines {
+    if {$expected != ""} {
+        if [string match $expected $output] {
+            pass "$test"
+        } else {
+            fail "$test $output"
+        }
+    } else {
+        break;
+    }
+}
+
+if [string match "main *" [lindex $output_lines 5]] {
+    fail "$test return from main"
+} else {
+    pass "$test"
+}
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()))
+}
+