[tip:perf/urgent] perf trace: Beautify mount's first pathname arg

[tip-bot for Arnaldo Carvalho de Melo]

Commit-ID:  23c07a23cbed389d0b9c7a06486574621df8d1a4
Gitweb:     https://git.kernel.org/tip/23c07a23cbed389d0b9c7a06486574621df8d1a4
Author:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Fri, 26 Oct 2018 13:51:45 -0300
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 30 Oct 2018 11:46:23 -0300

perf trace: Beautify mount's first pathname arg

The pathname beautifiers so far support just one augmented pathname per
syscall, so do it just for mount's first arg, later this will get fixed.

With:

  # perf probe -l
  probe:vfs_getname    (on getname_flags:73@acme/git/linux/fs/namei.c with pathname)
  #

Later this will get added to augmented_syscalls.c (eBPF):

In one xterm:

  # perf trace -e mount,umount
  2687.331 ( 3.544 ms): mount/8892 mount(dev_name: /mnt, dir_name: 0x561f9ac184a0, type: 0x561f9ac1b170, flags: BIND) = 0
  3912.126 ( 8.807 ms): umount/8895 umount2(name: /mnt) = 0
  ^C#

In the other:

  $ sudo mount --bind /proc /mnt
  $ sudo umount /mnt

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Benjamin Peterson <benjamin@xxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: https://lkml.kernel.org/n/tip-qsvhrm2es635cl4zicqjeth2@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/builtin-trace.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index d286f73ef2e5..dc8a6c4986ce 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -727,7 +727,8 @@ static struct syscall_fmt {
 		   [2] = { .scnprintf = SCA_MMAP_PROT,	/* prot */ },
 		   [3] = { .scnprintf = SCA_MMAP_FLAGS,	/* flags */ }, }, },
 	{ .name	    = "mount",
-	  .arg = { [3] = { .scnprintf = SCA_MOUNT_FLAGS, /* flags */
+	  .arg = { [0] = { .scnprintf = SCA_FILENAME, /* dev_name */ },
+		   [3] = { .scnprintf = SCA_MOUNT_FLAGS, /* flags */
 			   .mask_val  = SCAMV_MOUNT_FLAGS, /* flags */ }, }, },
 	{ .name	    = "mprotect",
 	  .arg = { [0] = { .scnprintf = SCA_HEX,	/* start */ },