perf probe: Search concrete out-of-line instances
Masami Hiramatsu [Thu, 11 Aug 2011 11:03:11 +0000 (20:03 +0900)]
gcc 4.6 generates a concrete out-of-line instance when there is a
function which is implicitly inlined somewhere but also has its own
instance. The concrete out-of-line instance means that it has an
abstract origin of the function which is referred by not only
inlined-subroutines but also a concrete subprogram.

Since current dwarf_func_inline_instances() can find only instances of
inlined-subroutines, this introduces new die_walk_instances() to find
both of subprogram and inlined-subroutines.

e.g. without this,
Available variables at sched_group_rt_period
        @<cpu_rt_period_read_uint+9>
                struct task_group*      tg

perf probe failed to find actual subprogram instance of
sched_group_rt_period().

With this,

Available variables at sched_group_rt_period
        @<cpu_rt_period_read_uint+9>
                struct task_group*      tg
        @<sched_group_rt_period+0>
                struct task_group*      tg

Now it found the sched_group_rt_period() itself.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20110811110311.19900.63997.stgit@fedora15
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/dwarf-aux.c
tools/perf/util/dwarf-aux.h
tools/perf/util/probe-finder.c

index 425703a..d0f4048 100644 (file)
@@ -453,6 +453,64 @@ Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
        return die_mem;
 }
 
+struct __instance_walk_param {
+       void    *addr;
+       int     (*callback)(Dwarf_Die *, void *);
+       void    *data;
+       int     retval;
+};
+
+static int __die_walk_instances_cb(Dwarf_Die *inst, void *data)
+{
+       struct __instance_walk_param *iwp = data;
+       Dwarf_Attribute attr_mem;
+       Dwarf_Die origin_mem;
+       Dwarf_Attribute *attr;
+       Dwarf_Die *origin;
+
+       attr = dwarf_attr(inst, DW_AT_abstract_origin, &attr_mem);
+       if (attr == NULL)
+               return DIE_FIND_CB_CONTINUE;
+
+       origin = dwarf_formref_die(attr, &origin_mem);
+       if (origin == NULL || origin->addr != iwp->addr)
+               return DIE_FIND_CB_CONTINUE;
+
+       iwp->retval = iwp->callback(inst, iwp->data);
+
+       return (iwp->retval) ? DIE_FIND_CB_END : DIE_FIND_CB_CONTINUE;
+}
+
+/**
+ * die_walk_instances - Walk on instances of given DIE
+ * @or_die: an abstract original DIE
+ * @callback: a callback function which is called with instance DIE
+ * @data: user data
+ *
+ * Walk on the instances of give @in_die. @in_die must be an inlined function
+ * declartion. This returns the return value of @callback if it returns
+ * non-zero value, or -ENOENT if there is no instance.
+ */
+int die_walk_instances(Dwarf_Die *or_die, int (*callback)(Dwarf_Die *, void *),
+                      void *data)
+{
+       Dwarf_Die cu_die;
+       Dwarf_Die die_mem;
+       struct __instance_walk_param iwp = {
+               .addr = or_die->addr,
+               .callback = callback,
+               .data = data,
+               .retval = -ENOENT,
+       };
+
+       if (dwarf_diecu(or_die, &cu_die, NULL, NULL) == NULL)
+               return -ENOENT;
+
+       die_find_child(&cu_die, __die_walk_instances_cb, &iwp, &die_mem);
+
+       return iwp.retval;
+}
+
 /* Line walker internal parameters */
 struct __line_walk_param {
        bool recursive;
index 6f46106..6ce1717 100644 (file)
@@ -80,6 +80,10 @@ extern Dwarf_Die *die_find_realfunc(Dwarf_Die *cu_die, Dwarf_Addr addr,
 extern Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
                                      Dwarf_Die *die_mem);
 
+/* Walk on the instances of given DIE */
+extern int die_walk_instances(Dwarf_Die *in_die,
+                             int (*callback)(Dwarf_Die *, void *), void *data);
+
 /* Walker on lines (Note: line number will not be sorted) */
 typedef int (* line_walk_callback_t) (const char *fname, int lineno,
                                      Dwarf_Addr addr, void *data);
index 114542a..555fc38 100644 (file)
@@ -924,42 +924,39 @@ static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
        return die_walk_lines(sp_die, probe_point_lazy_walker, pf);
 }
 
-/* Callback parameter with return value */
-struct dwarf_callback_param {
-       void *data;
-       int retval;
-};
-
 static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
 {
-       struct dwarf_callback_param *param = data;
-       struct probe_finder *pf = param->data;
+       struct probe_finder *pf = data;
        struct perf_probe_point *pp = &pf->pev->point;
        Dwarf_Addr addr;
+       int ret;
 
        if (pp->lazy_line)
-               param->retval = find_probe_point_lazy(in_die, pf);
+               ret = find_probe_point_lazy(in_die, pf);
        else {
                /* Get probe address */
                if (dwarf_entrypc(in_die, &addr) != 0) {
                        pr_warning("Failed to get entry address of %s.\n",
                                   dwarf_diename(in_die));
-                       param->retval = -ENOENT;
-                       return DWARF_CB_ABORT;
+                       return -ENOENT;
                }
                pf->addr = addr;
                pf->addr += pp->offset;
                pr_debug("found inline addr: 0x%jx\n",
                         (uintmax_t)pf->addr);
 
-               param->retval = call_probe_finder(in_die, pf);
-               if (param->retval < 0)
-                       return DWARF_CB_ABORT;
+               ret = call_probe_finder(in_die, pf);
        }
 
-       return DWARF_CB_OK;
+       return ret;
 }
 
+/* Callback parameter with return value for libdw */
+struct dwarf_callback_param {
+       void *data;
+       int retval;
+};
+
 /* Search function from function name */
 static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
 {
@@ -996,14 +993,10 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
                        /* TODO: Check the address in this function */
                        param->retval = call_probe_finder(sp_die, pf);
                }
-       } else {
-               struct dwarf_callback_param _param = {.data = (void *)pf,
-                                                     .retval = 0};
+       } else
                /* Inlined function: search instances */
-               dwarf_func_inline_instances(sp_die, probe_point_inline_cb,
-                                           &_param);
-               param->retval = _param.retval;
-       }
+               param->retval = die_walk_instances(sp_die,
+                                       probe_point_inline_cb, (void *)pf);
 
        return DWARF_CB_ABORT; /* Exit; no same symbol in this CU. */
 }
@@ -1452,16 +1445,14 @@ static int find_line_range_by_line(Dwarf_Die *sp_die, struct line_finder *lf)
 
 static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
 {
-       struct dwarf_callback_param *param = data;
-
-       param->retval = find_line_range_by_line(in_die, param->data);
+       find_line_range_by_line(in_die, data);
 
        /*
         * We have to check all instances of inlined function, because
         * some execution paths can be optimized out depends on the
         * function argument of instances
         */
-       return DWARF_CB_OK;
+       return 0;
 }
 
 /* Search function from function name */
@@ -1489,15 +1480,10 @@ 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)) {
-                       struct dwarf_callback_param _param;
-                       _param.data = (void *)lf;
-                       _param.retval = 0;
-                       dwarf_func_inline_instances(sp_die,
-                                                   line_range_inline_cb,
-                                                   &_param);
-                       param->retval = _param.retval;
-               } else
+               if (dwarf_func_inline(sp_die))
+                       param->retval = die_walk_instances(sp_die,
+                                               line_range_inline_cb, lf);
+               else
                        param->retval = find_line_range_by_line(sp_die, lf);
                return DWARF_CB_ABORT;
        }