linux-kernel - [PATCH -tip 2/7] [BUGFIX] perf probe: Fix local variable searching loop

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Date:	Thu, 21 Oct 2010 19:13:09 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Ingo Molnar <mingo@...e.hu>
Cc:	Steven Rostedt <rostedt@...dmis.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org, 2nddept-manager@....hitachi.co.jp,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>, Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH -tip 2/7] [BUGFIX] perf probe: Fix local variable searching
	loop

Fix to check the die's address and search into the die
only if it has given address.
This will avoid finding wrong variables in wrong
basic block.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.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@...hat.com>
Cc: linux-kernel@...r.kernel.org
---

 tools/perf/util/probe-finder.c |   26 ++++++++++++++++++--------
 1 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index a2d1f79..abcaec5 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -329,25 +329,35 @@ static Dwarf_Die *die_find_inlinefunc(Dwarf_Die *sp_die, Dwarf_Addr addr,
 	return die_find_child(sp_die, __die_find_inline_cb, &addr, die_mem);
 }
 
+struct __find_variable_param {
+	const char *name;
+	Dwarf_Addr addr;
+};
+
 static int __die_find_variable_cb(Dwarf_Die *die_mem, void *data)
 {
-	const char *name = data;
+	struct __find_variable_param *fvp = data;
 	int tag;
 
 	tag = dwarf_tag(die_mem);
 	if ((tag == DW_TAG_formal_parameter ||
 	     tag == DW_TAG_variable) &&
-	    die_compare_name(die_mem, name))
+	    die_compare_name(die_mem, fvp->name))
 		return DIE_FIND_CB_FOUND;
 
-	return DIE_FIND_CB_CONTINUE;
+	if (dwarf_haspc(die_mem, fvp->addr))
+		return DIE_FIND_CB_CONTINUE;
+	else
+		return DIE_FIND_CB_SIBLING;
 }
 
-/* Find a variable called 'name' */
-static Dwarf_Die *die_find_variable(Dwarf_Die *sp_die, const char *name,
-				    Dwarf_Die *die_mem)
+/* Find a variable called 'name' at given address */
+static Dwarf_Die *die_find_variable_at(Dwarf_Die *sp_die, const char *name,
+				       Dwarf_Addr addr, Dwarf_Die *die_mem)
 {
-	return die_find_child(sp_die, __die_find_variable_cb, (void *)name,
+	struct __find_variable_param fvp = { .name = name, .addr = addr};
+
+	return die_find_child(sp_die, __die_find_variable_cb, (void *)&fvp,
 			      die_mem);
 }
 
@@ -731,7 +741,7 @@ static int find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
 	pr_debug("Searching '%s' variable in context.\n",
 		 pf->pvar->var);
 	/* Search child die for local variables and parameters. */
-	if (die_find_variable(sp_die, pf->pvar->var, &vr_die))
+	if (die_find_variable_at(sp_die, pf->pvar->var, pf->addr, &vr_die))
 		ret = convert_variable(&vr_die, pf);
 	else {
 		/* Search upper class */

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