linux-kernel - [PATCH 4.9 059/171] perf probe: Fix to show calling lines of inlined functions

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Message-Id: <20200102220555.093184715@linuxfoundation.org>
Date:   Thu,  2 Jan 2020 23:06:30 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Masami Hiramatsu <mhiramat@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 059/171] perf probe: Fix to show calling lines of inlined functions

From: Masami Hiramatsu <mhiramat@...nel.org>

[ Upstream commit 86c0bf8539e7f46d91bd105e55eda96e0064caef ]

Fix to show calling lines of inlined functions (where an inline function
is called).

die_walk_lines() filtered out the lines inside inlined functions based
on the address. However this also filtered out the lines which call
those inlined functions from the target function.

To solve this issue, check the call_file and call_line attributes and do
not filter out if it matches to the line information.

Without this fix, perf probe -L doesn't show some lines correctly.
(don't see the lines after 17)

  # perf probe -L vfs_read
  <vfs_read@...me/mhiramat/ksrc/linux/fs/read_write.c:0>
        0  ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
        1  {
        2         ssize_t ret;

        4         if (!(file->f_mode & FMODE_READ))
                          return -EBADF;
        6         if (!(file->f_mode & FMODE_CAN_READ))
                          return -EINVAL;
        8         if (unlikely(!access_ok(buf, count)))
                          return -EFAULT;

       11         ret = rw_verify_area(READ, file, pos, count);
       12         if (!ret) {
       13                 if (count > MAX_RW_COUNT)
                                  count =  MAX_RW_COUNT;
       15                 ret = __vfs_read(file, buf, count, pos);
       16                 if (ret > 0) {
                                  fsnotify_access(file);
                                  add_rchar(current, ret);
                          }

With this fix:

  # perf probe -L vfs_read
  <vfs_read@...me/mhiramat/ksrc/linux/fs/read_write.c:0>
        0  ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
        1  {
        2         ssize_t ret;

        4         if (!(file->f_mode & FMODE_READ))
                          return -EBADF;
        6         if (!(file->f_mode & FMODE_CAN_READ))
                          return -EINVAL;
        8         if (unlikely(!access_ok(buf, count)))
                          return -EFAULT;

       11         ret = rw_verify_area(READ, file, pos, count);
       12         if (!ret) {
       13                 if (count > MAX_RW_COUNT)
                                  count =  MAX_RW_COUNT;
       15                 ret = __vfs_read(file, buf, count, pos);
       16                 if (ret > 0) {
       17                         fsnotify_access(file);
       18                         add_rchar(current, ret);
                          }
       20                 inc_syscr(current);
                  }

Fixes: 4cc9cec636e7 ("perf probe: Introduce lines walker interface")
Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Link: http://lore.kernel.org/lkml/157241937995.32002.17899884017011512577.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 tools/perf/util/dwarf-aux.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index 3aea343c7179..41bfb4c977d0 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -765,7 +765,7 @@ 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, *decf = NULL;
+	const char *fname, *decf = NULL, *inf = NULL;
 	int lineno, ret = 0;
 	int decl = 0, inl;
 	Dwarf_Die die_mem, *cu_die;
@@ -809,13 +809,21 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
 			 */
 			if (!dwarf_haspc(rt_die, addr))
 				continue;
+
 			if (die_find_inlinefunc(rt_die, addr, &die_mem)) {
+				/* Call-site check */
+				inf = die_get_call_file(&die_mem);
+				if ((inf && !strcmp(inf, decf)) &&
+				    die_get_call_lineno(&die_mem) == lineno)
+					goto found;
+
 				dwarf_decl_line(&die_mem, &inl);
 				if (inl != decl ||
 				    decf != dwarf_decl_file(&die_mem))
 					continue;
 			}
 		}
+found:
 		/* Get source line */
 		fname = dwarf_linesrc(line, NULL, NULL);
 
-- 
2.20.1