linux-kernel - [BUGFIX PATCH perf/core ] perf-probe: Fix to show lines of sys

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Date:	Wed, 12 Aug 2015 10:24:07 +0900
From:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:	Namhyung Kim <namhyung@...nel.org>, Jiri Olsa <jolsa@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>
Subject: [BUGFIX PATCH perf/core ] perf-probe: Fix to show lines of sys_
 functions correctly

"perf probe --lines sys_poll" shows only the first line of
sys_poll, because the SYSCALL_DEFINE macro
----
SYSCALL_DEFINE*(foo,...)
{
  body;
}
----
is expanded as below (on debuginfo)

----
static inline int SYSC_foo(...)
{
  body;
}
int SyS_foo(...) <- is an alias of sys_foo.
{
  return SYSC_foo(...);
}
----

So, "perf probe --lines sys_foo" decodes SyS_foo function and
it also skips inlined functions(SYSC_foo) inside the target
function because those functions are usually defined somewhere
else.

To fix this issue, this fix checks whether the inlined function
is defined at the same point of the target function, and if so,
it doesn't skip the inline function.

Reported-by: Arnaldo Carvalho de Melo <acme@...nel.org>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
---
 tools/perf/util/dwarf-aux.c |   18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 57f3ef4..445f455 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -734,15 +734,18 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
 	Dwarf_Lines *lines;
 	Dwarf_Line *line;
 	Dwarf_Addr addr;
-	const char *fname;
+	const char *fname, *decf = NULL;
 	int lineno, ret = 0;
+	int decl = 0, inl;
 	Dwarf_Die die_mem, *cu_die;
 	size_t nlines, i;
 
 	/* Get the CU die */
-	if (dwarf_tag(rt_die) != DW_TAG_compile_unit)
+	if (dwarf_tag(rt_die) != DW_TAG_compile_unit) {
 		cu_die = dwarf_diecu(rt_die, &die_mem, NULL, NULL);
-	else
+		dwarf_decl_line(rt_die, &decl);
+		decf = dwarf_decl_file(rt_die);
+	} else
 		cu_die = rt_die;
 	if (!cu_die) {
 		pr_debug2("Failed to get CU from given DIE.\n");
@@ -773,9 +776,14 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
 			 * The line is included in given function, and
 			 * no inline block includes it.
 			 */
-			if (!dwarf_haspc(rt_die, addr) ||
-			    die_find_inlinefunc(rt_die, addr, &die_mem))
+			if (!dwarf_haspc(rt_die, addr))
 				continue;
+			if (die_find_inlinefunc(rt_die, addr, &die_mem)) {
+				dwarf_decl_line(&die_mem, &inl);
+				if (inl != decl ||
+				    decf != dwarf_decl_file(&die_mem))
+					continue;
+			}
 		/* Get source line */
 		fname = dwarf_linesrc(line, NULL, NULL);
 

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