perf test: Fix dwarf unwind using libunwind.

[cascardo/linux.git] / tools / perf / tests / dwarf-unwind.c

diff --git a/tools/perf/tests/dwarf-unwind.c b/tools/perf/tests/dwarf-unwind.c
index ab28cca..0bf06be 100644 (file)
--- a/tools/perf/tests/dwarf-unwind.c
+++ b/tools/perf/tests/dwarf-unwind.c
@@ -11,6 +11,9 @@
 #include "thread.h"
 #include "callchain.h"
 
+/* For bsearch. We try to unwind functions in shared object. */
+#include <stdlib.h>
+
 static int mmap_handler(struct perf_tool *tool __maybe_unused,
                        union perf_event *event,
                        struct perf_sample *sample __maybe_unused,
@@ -28,7 +31,7 @@ static int init_live_machine(struct machine *machine)
                                                  mmap_handler, machine, true);
 }
 
-#define MAX_STACK 6
+#define MAX_STACK 8
 
 static int unwind_entry(struct unwind_entry *entry, void *arg)
 {
@@ -37,6 +40,8 @@ static int unwind_entry(struct unwind_entry *entry, void *arg)
        static const char *funcs[MAX_STACK] = {
                "test__arch_unwind_sample",
                "unwind_thread",
+               "compare",
+               "bsearch",
                "krava_3",
                "krava_2",
                "krava_1",
@@ -88,10 +93,37 @@ static int unwind_thread(struct thread *thread)
        return err;
 }
 
+static int global_unwind_retval = -INT_MAX;
+
+__attribute__ ((noinline))
+static int compare(void *p1, void *p2)
+{
+       /* Any possible value should be 'thread' */
+       struct thread *thread = *(struct thread **)p1;
+
+       if (global_unwind_retval == -INT_MAX)
+               global_unwind_retval = unwind_thread(thread);
+
+       return p1 - p2;
+}
+
 __attribute__ ((noinline))
 static int krava_3(struct thread *thread)
 {
-       return unwind_thread(thread);
+       struct thread *array[2] = {thread, thread};
+       void *fp = &bsearch;
+       /*
+        * make _bsearch a volatile function pointer to
+        * prevent potential optimization, which may expand
+        * bsearch and call compare directly from this function,
+        * instead of libc shared object.
+        */
+       void *(*volatile _bsearch)(void *, void *, size_t,
+                       size_t, int (*)(void *, void *));
+
+       _bsearch = fp;
+       _bsearch(array, &thread, 2, sizeof(struct thread **), compare);
+       return global_unwind_retval;
 }
 
 __attribute__ ((noinline))