linux-kernel - [PATCH 09/13] perf probe: Fix to show lines of sys

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Message-Id: <1439397601-26918-10-git-send-email-acme@kernel.org>
Date:	Wed, 12 Aug 2015 13:39:57 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 09/13] perf probe: Fix to show lines of sys_ functions correctly

From: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>

"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>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Link: http://lkml.kernel.org/r/20150812012406.11811.94691.stgit@localhost.localdomain
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.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 57f3ef41c2bc..445f455dd377 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);
 
-- 
2.1.0

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