perf trace beauty ioctl: Fix off-by-one error in cmd->string table
authorBenjamin Peterson <benjamin@python.org>
Fri, 23 Aug 2019 03:36:25 +0000 (20:36 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 5 Oct 2019 10:47:56 +0000 (12:47 +0200)
commitd792650edbf054cc528dfb8756405cfc978c7996
tree4f3ff6919bbb077cdb0e8c1df4ea6a76fa1e4801
parent254f02e17d182c43370c17d5c7fd5bdda531f3d8
perf trace beauty ioctl: Fix off-by-one error in cmd->string table

[ Upstream commit b92675f4a9c02dd78052645597dac9e270679ddf ]

While tracing a program that calls isatty(3), I noticed that strace
reported TCGETS for the request argument of the underlying ioctl(2)
syscall while perf trace reported TCSETS. strace is corrrect. The bug in
perf was due to the tty ioctl beauty table starting at 0x5400 rather
than 0x5401.

Committer testing:

  Using augmented_raw_syscalls.o and settings to make 'perf trace'
  use strace formatting, i.e. with this in ~/.perfconfig

  # cat ~/.perfconfig
  [trace]
add_events = /home/acme/git/linux/tools/perf/examples/bpf/augmented_raw_syscalls.c
show_zeros = yes
show_duration = no
no_inherit = yes
show_timestamp = no
show_arg_names = no
args_alignment = 40
show_prefix = yes

  # strace -e ioctl stty > /dev/null
  ioctl(0, TCGETS, {B38400 opost isig icanon echo ...}) = 0
  ioctl(1, TIOCGWINSZ, 0x7fff8a9b0860)    = -1 ENOTTY (Inappropriate ioctl for device)
  ioctl(1, TCGETS, 0x7fff8a9b0540)        = -1 ENOTTY (Inappropriate ioctl for device)
  +++ exited with 0 +++
  #

Before:

  # perf trace -e ioctl stty > /dev/null
  ioctl(0, TCSETS, 0x7fff2cf79f20)        = 0
  ioctl(1, TIOCSWINSZ, 0x7fff2cf79f40)    = -1 ENOTTY (Inappropriate ioctl for device)
  ioctl(1, TCSETS, 0x7fff2cf79c20)        = -1 ENOTTY (Inappropriate ioctl for device)
  #

After:

  # perf trace -e ioctl stty > /dev/null
  ioctl(0, TCGETS, 0x7ffed0763920)        = 0
  ioctl(1, TIOCGWINSZ, 0x7ffed0763940)    = -1 ENOTTY (Inappropriate ioctl for device)
  ioctl(1, TCGETS, 0x7ffed0763620)        = -1 ENOTTY (Inappropriate ioctl for device)
  #

Signed-off-by: Benjamin Peterson <benjamin@python.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 1cc47f2d46206d67285aea0ca7e8450af571da13 ("perf trace beauty ioctl: Improve 'cmd' beautifier")
Link: http://lkml.kernel.org/r/20190823033625.18814-1-benjamin@python.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tools/perf/trace/beauty/ioctl.c