perf probe: Fix to handle optimized not-inlined functions

Fix to handle optimized no-inline functions which have only function
definition but no actual instance at that point.

To fix this problem, we need to find actual instance of the function.

Without this patch:
  ----
  # perf probe -a __up
  Failed to get entry address of __up.
    Error: Failed to add events.
  # perf probe -L __up
  Specified source line is not found.
    Error: Failed to show lines.
  ----

With this patch:
  ----
  # perf probe -a __up
  Added new event:
    probe:__up           (on __up)

  You can now use it in all perf tools, such as:

          perf record -e probe:__up -aR sleep 1

  # perf probe -L __up
  <__up@/home/fedora/ksrc/linux-3/kernel/locking/semaphore.c:0>
        0  static noinline void __sched __up(struct semaphore *sem)
           {
                  struct semaphore_waiter *waiter = list_first_entry(&sem->wait_
                                                          struct semaphore_waite
        4         list_del(&waiter->list);
        5         waiter->up = true;
        6         wake_up_process(waiter->task);
        7  }
  ----

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150130093744.30575.43290.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index cc66c4049e0921ea35910edcebffb89b525c2f57..780b2bc11128b7456c82b686f3f9bad68a964127 100644 (file)
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -277,6 +277,21 @@ bool die_is_func_def(Dwarf_Die *dw_die)
                dwarf_attr(dw_die, DW_AT_declaration, &attr) == NULL);
 }
 
+/**
+ * die_is_func_instance - Ensure that this DIE is an instance of a subprogram
+ * @dw_die: a DIE
+ *
+ * Ensure that this DIE is an instance (which has an entry address).
+ * This returns true if @dw_die is a function instance. If not, you need to
+ * call die_walk_instances() to find actual instances.
+ **/
+bool die_is_func_instance(Dwarf_Die *dw_die)
+{
+       Dwarf_Addr tmp;
+
+       /* Actually gcc optimizes non-inline as like as inlined */
+       return !dwarf_func_inline(dw_die) && dwarf_entrypc(dw_die, &tmp) == 0;
+}
 /**
  * die_get_data_member_location - Get the data-member offset
  * @mb_die: a DIE of a member of a data structure

diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
index b4fe90c6cb2d4413c3ab96f91a346f3f89549932..af7dbcd5f929947cfdd0b146f20ad65d45059bb8 100644 (file)
--- a/tools/perf/util/dwarf-aux.h
+++ b/tools/perf/util/dwarf-aux.h
@@ -41,6 +41,9 @@ extern int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,
 /* Ensure that this DIE is a subprogram and definition (not declaration) */
 extern bool die_is_func_def(Dwarf_Die *dw_die);
 
+/* Ensure that this DIE is an instance of a subprogram */
+extern bool die_is_func_instance(Dwarf_Die *dw_die);
+
 /* Compare diename and tname */
 extern bool die_compare_name(Dwarf_Die *dw_die, const char *tname);
 

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index b5247d777f0e9348d1b77e3f33813c5b7713bce4..d14193518e4d09d2b57954ef449e4e9238eb5c4c 100644 (file)
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -915,17 +915,13 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
                dwarf_decl_line(sp_die, &pf->lno);
                pf->lno += pp->line;
                param->retval = find_probe_point_by_line(pf);
-       } else if (!dwarf_func_inline(sp_die)) {
+       } else if (die_is_func_instance(sp_die)) {
+               /* Instances always have the entry address */
+               dwarf_entrypc(sp_die, &pf->addr);
                /* Real function */
                if (pp->lazy_line)
                        param->retval = find_probe_point_lazy(sp_die, pf);
                else {
-                       if (dwarf_entrypc(sp_die, &pf->addr) != 0) {
-                               pr_warning("Failed to get entry address of "
-                                          "%s.\n", dwarf_diename(sp_die));
-                               param->retval = -ENOENT;
-                               return DWARF_CB_ABORT;
-                       }
                        pf->addr += pp->offset;
                        /* TODO: Check the address in this function */
                        param->retval = call_probe_finder(sp_die, pf);
@@ -1536,7 +1532,7 @@ static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
                pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
                lr->start = lf->lno_s;
                lr->end = lf->lno_e;
-               if (dwarf_func_inline(sp_die))
+               if (!die_is_func_instance(sp_die))
                        param->retval = die_walk_instances(sp_die,
                                                line_range_inline_cb, lf);
                else