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

Masami Hiramatsu
2011-08-11T11:26:49Z

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@/home/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@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.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;
}