linux-kernel - [PATCH v2] perf report: do not drop last inlined frame

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Message-Id: <20170518083822.14568-1-milian.wolff@kdab.com>
Date:   Thu, 18 May 2017 10:38:22 +0200
From:   Milian Wolff <milian.wolff@...b.com>
To:     Linux-kernel@...r.kernel.org
Cc:     linux-perf-users@...r.kernel.org,
        Milian Wolff <milian.wolff@...b.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        David Ahern <dsahern@...il.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Yao Jin <yao.jin@...ux.intel.com>
Subject: [PATCH v2] perf report: do not drop last inlined frame

The very last inlined frame, i.e. the one furthest away from the
non-inlined frame, was silently dropped. This is apparent when
comparing the output of `perf script` and `addr2line`:

~~~~~~
$ perf script --inline
...
a.out 26722 80836.309329:      72425 cycles:
                   21493 __hypot_finite (/usr/lib/libm-2.25.so)
                     a4a std::abs<double> (inline) (/tmp/a.out)
                     a4a std::_Norm_helper<true>::_S_do_it<double> (inline) (/tmp/a.out)
                     a4a std::norm<double> (inline) (/tmp/a.out)
                     a4a main (/tmp/a.out)
                   20510 __libc_start_main (/usr/lib/libc-2.25.so)
                     bd9 _start (/tmp/a.out)

$ addr2line -a -f -i -e /tmp/a.out a4a | c++filt
0x0000000000000a4a
std::__complex_abs(doublecomplex )
/usr/include/c++/6.3.1/complex:589
double std::abs<double>(std::complex<double> const&)
/usr/include/c++/6.3.1/complex:597
double std::_Norm_helper<true>::_S_do_it<double>(std::complex<double> const&)
/usr/include/c++/6.3.1/complex:654
double std::norm<double>(std::complex<double> const&)
/usr/include/c++/6.3.1/complex:664
main
/tmp/inlining.cpp:14
~~~~~

Note how `std::__complex_abs` is missing from the `perf script`
output. This is similarly showing up in `perf report`. The patch
here fixes this issue, and the output becomes:

~~~~~
a.out 26722 80836.309329:      72425 cycles:
                   21493 __hypot_finite (/usr/lib/libm-2.25.so)
                    ace3 hypot (/usr/lib/libm-2.25.so)
                     a4a std::__complex_abs (inline) (/tmp/a.out)
                     a4a std::abs<double> (inline) (/tmp/a.out)
                     a4a std::_Norm_helper<true>::_S_do_it<double> (inline) (/tmp/a.out)
                     a4a std::norm<double> (inline) (/tmp/a.out)
                     a4a main (/tmp/a.out)
                   20510 __libc_start_main (/usr/lib/libc-2.25.so)
                     bd9 _start (/tmp/a.out)
~~~~~

Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Yao Jin <yao.jin@...ux.intel.com>
Signed-off-by: Milian Wolff <milian.wolff@...b.com>
---
 tools/perf/util/srcline.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

v2:
- rebase against patch fixing memleak in addr2lines

diff --git a/tools/perf/util/srcline.c b/tools/perf/util/srcline.c
index bbba9c69cfec..168285d37cd2 100644
--- a/tools/perf/util/srcline.c
+++ b/tools/perf/util/srcline.c
@@ -203,6 +203,16 @@ static void addr2line_cleanup(struct a2l_data *a2l)
 
 #define MAX_INLINE_NEST 1024
 
+static int inline_list__append_dso_a2l(struct dso *dso,
+				       struct inline_node *node)
+{
+	struct a2l_data *a2l = dso->a2l;
+	char *funcname = a2l->funcname ? strdup(a2l->funcname) : NULL;
+	char *filename = a2l->filename ? strdup(a2l->filename) : NULL;
+
+	return inline_list__append(filename, funcname, a2l->line, node, dso);
+}
+
 static int addr2line(const char *dso_name, u64 addr,
 		     char **file, unsigned int *line, struct dso *dso,
 		     bool unwind_inlines, struct inline_node *node)
@@ -231,15 +241,15 @@ static int addr2line(const char *dso_name, u64 addr,
 	if (unwind_inlines) {
 		int cnt = 0;
 
+		if (node && inline_list__append_dso_a2l(dso, node))
+			return 0;
+
 		while (bfd_find_inliner_info(a2l->abfd, &a2l->filename,
 					     &a2l->funcname, &a2l->line) &&
 		       cnt++ < MAX_INLINE_NEST) {
 
 			if (node != NULL) {
-				if (inline_list__append(strdup(a2l->filename),
-							strdup(a2l->funcname),
-							a2l->line, node,
-							dso) != 0)
+				if (inline_list__append_dso_a2l(dso, node))
 					return 0;
 				// found at least one inline frame
 				ret = 1;
-- 
2.13.0