linux-kernel - [PATCH -tip ] perf probe: Fix finder to find lines of given function

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Date:	Mon, 23 Apr 2012 12:24:36 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org, yrl.pp-manager.tt@...achi.com,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Prashanth Nageshappa <prashanth@...ux.vnet.ibm.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Ingo Molnar <mingo@...e.hu>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH -tip ] perf probe: Fix finder to find lines of given function

The commit ba28c59bc9ed8fb7b9a753cd88ee54a2c4f6265b fixed
a declaration entry bug in probe_point_search_cb().
There are same bugs in line finder and call_probe_finder().
This introduces a new dwarf utility function to determine
given DIE is a function definition, not declaration.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Prashanth Nageshappa <prashanth@...ux.vnet.ibm.com>
Cc: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---

 tools/perf/util/dwarf-aux.c    |   19 +++++++++++++++++++
 tools/perf/util/dwarf-aux.h    |    3 +++
 tools/perf/util/probe-finder.c |   12 +++++-------
 3 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index ee51e9b..66a76e5 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -263,6 +263,21 @@ bool die_is_signed_type(Dwarf_Die *tp_die)
 }
 
 /**
+ * die_is_func_def - Ensure that this DIE is a subprogram and definition
+ * @dw_die: a DIE
+ *
+ * Ensure that this DIE is a subprogram and NOT a declaration. This
+ * returns true if @dw_die is a function definition.
+ **/
+bool die_is_func_def(Dwarf_Die *dw_die)
+{
+	Dwarf_Attribute attr;
+
+	return (dwarf_tag(dw_die) == DW_TAG_subprogram &&
+		dwarf_attr(dw_die, DW_AT_declaration, &attr) == NULL);
+}
+
+/**
  * die_get_data_member_location - Get the data-member offset
  * @mb_die: a DIE of a member of a data structure
  * @offs: The offset of the member in the data structure
@@ -392,6 +407,10 @@ static int __die_search_func_cb(Dwarf_Die *fn_die, void *data)
 {
 	struct __addr_die_search_param *ad = data;
 
+	/*
+	 * Since a declaration entry doesn't has given pc, this always returns
+	 * function definition entry.
+	 */
 	if (dwarf_tag(fn_die) == DW_TAG_subprogram &&
 	    dwarf_haspc(fn_die, ad->addr)) {
 		memcpy(ad->die_mem, fn_die, sizeof(Dwarf_Die));
diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h
index 6ce1717..8658d41 100644
--- a/tools/perf/util/dwarf-aux.h
+++ b/tools/perf/util/dwarf-aux.h
@@ -38,6 +38,9 @@ extern int cu_find_lineinfo(Dwarf_Die *cudie, unsigned long addr,
 extern int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,
 			int (*callback)(Dwarf_Die *, void *), void *data);
 
+/* Ensure that this DIE is a subprogram and definition (not declaration) */
+extern bool die_is_func_def(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 d448984..d793c0a 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -726,7 +726,7 @@ static int call_probe_finder(Dwarf_Die *sc_die, struct probe_finder *pf)
 	}
 
 	/* If not a real subprogram, find a real one */
-	if (dwarf_tag(sc_die) != DW_TAG_subprogram) {
+	if (!die_is_func_def(sc_die)) {
 		if (!die_find_realfunc(&pf->cu_die, pf->addr, &pf->sp_die)) {
 			pr_warning("Failed to find probe point in any "
 				   "functions.\n");
@@ -972,12 +972,10 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
 	struct dwarf_callback_param *param = data;
 	struct probe_finder *pf = param->data;
 	struct perf_probe_point *pp = &pf->pev->point;
-	Dwarf_Attribute attr;
 
 	/* Check tag and diename */
-	if (dwarf_tag(sp_die) != DW_TAG_subprogram ||
-	    !die_compare_name(sp_die, pp->function) ||
-	    dwarf_attr(sp_die, DW_AT_declaration, &attr))
+	if (!die_is_func_def(sp_die) ||
+	    !die_compare_name(sp_die, pp->function))
 		return DWARF_CB_OK;
 
 	/* Check declared file */
@@ -1466,7 +1464,7 @@ static int line_range_inline_cb(Dwarf_Die *in_die, void *data)
 	return 0;
 }
 
-/* Search function from function name */
+/* Search function definition from function name */
 static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
 {
 	struct dwarf_callback_param *param = data;
@@ -1477,7 +1475,7 @@ static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
 	if (lr->file && strtailcmp(lr->file, dwarf_decl_file(sp_die)))
 		return DWARF_CB_OK;
 
-	if (dwarf_tag(sp_die) == DW_TAG_subprogram &&
+	if (die_is_func_def(sp_die) &&
 	    die_compare_name(sp_die, lr->function)) {
 		lf->fname = dwarf_decl_file(sp_die);
 		dwarf_decl_line(sp_die, &lr->offset);

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