linux-kernel - [PATCH -tip v2 2/9] [BUGFIX] perf probe: Fix line walker to check CU correctly

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Date:	Thu, 11 Aug 2011 20:02:35 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Ingo Molnar <mingo@...e.hu>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Pekka Enberg <penberg@...nel.org>,
	linux-kernel@...r.kernel.org, yrl.pp-manager.tt@...achi.com,
	Masami Hiramatsu <masami.hiramatsu@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>, Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>
Subject: [PATCH -tip v2 2/9] [BUGFIX] perf probe: Fix line walker to check CU
 correctly

Fix line walker to check whether a given DIE is CU or not.
Actually this function accepts CU, subprogram and
inlined_subroutine DIEs.

Without this fix, perf probe always fails to analyze lines
on inlined functions;

$ perf probe -L pre_schedule
Debuginfo analysis failed. (-2)
  Error: Failed to show lines. (-2)

This fixes that bug, as below.

$ perf probe -L pre_schedule
<pre_schedule@...me/mhiramat/ksrc/linux-2.6/kernel/sched.c:0>
      0  static inline void pre_schedule(struct rq *rq, struct task_struct *prev
         {
      2         if (prev->sched_class->pre_schedule)
      3                 prev->sched_class->pre_schedule(rq, prev);
         }

         /* rq->lock is NOT held, but preemption is disabled */


Changes from v1:
 - Update against current tip tree.(Fix dwarf-aux.c)

Signed-off-by: Masami Hiramatsu <masami.hiramatsu@...il.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Arnaldo Carvalho de Melo <acme@...stprotocols.net>
---

 tools/perf/util/dwarf-aux.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index fddf40f..d35b454 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -439,7 +439,7 @@ static int __die_walk_culines_cb(Dwarf_Die *sp_die, void *data)
 
 /**
  * die_walk_lines - Walk on lines inside given DIE
- * @rt_die: a root DIE (CU or subprogram)
+ * @rt_die: a root DIE (CU, subprogram or inlined_subroutine)
  * @callback: callback routine
  * @data: user data
  *
@@ -460,12 +460,12 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
 	size_t nlines, i;
 
 	/* Get the CU die */
-	if (dwarf_tag(rt_die) == DW_TAG_subprogram)
+	if (dwarf_tag(rt_die) != DW_TAG_compile_unit)
 		cu_die = dwarf_diecu(rt_die, &die_mem, NULL, NULL);
 	else
 		cu_die = rt_die;
 	if (!cu_die) {
-		pr_debug2("Failed to get CU from subprogram\n");
+		pr_debug2("Failed to get CU from given DIE.\n");
 		return -EINVAL;
 	}
 

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