linux-toradex.git/tools/objtool, branch v4.6-rc2

objtool: Only print one warning per function

2016-03-09T09:48:10+00:00

When objtool discovers an issue, it's very common for it to flood the
terminal with a lot of duplicate warnings.  For example:

  warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch
  warning: objtool: rtlwifi_rate_mapping()+0x2f3: frame pointer state mismatch
  warning: objtool: rtlwifi_rate_mapping()+0x2ff: frame pointer state mismatch
  warning: objtool: rtlwifi_rate_mapping()+0x30b: frame pointer state mismatch
  ...

The first warning is usually all you need.  Change it to only warn once
per function.

Suggested-by: Ingo Molnar 
Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/c47f3ca38aa01e2a9b6601f9e38efd414c3f3c18.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Add several performance improvements

2016-03-09T09:48:10+00:00

Use hash tables for instruction and rela lookups (and keep the linked
lists around for sequential access).

Also cache the section struct for the "__func_stack_frame_non_standard"
section.

With this change, "objtool check net/wireless/nl80211.o" goes from:

  real	0m1.168s
  user	0m1.163s
  sys	0m0.005s

to:

  real	0m0.059s
  user	0m0.042s
  sys	0m0.017s

for a 20x speedup.

With the same object, it should be noted that the memory heap usage grew
from 8MB to 62MB.  Reducing the memory usage is on the TODO list.

Reported-by: Ingo Molnar 
Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/dd0d8e1449506cfa7701b4e7ba73577077c44253.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Fix false positive warnings for functions with multiple switch statements

2016-03-09T09:48:09+00:00

Ingo reported [1] some false positive objtool warnings:

  drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2e7: frame pointer state mismatch
  drivers/net/wireless/realtek/rtlwifi/base.o: warning: objtool: rtlwifi_rate_mapping()+0x2f3: frame pointer state mismatch
  ...

And so did the 0-day bot [2]:

  drivers/gpu/drm/radeon/cik.o: warning: objtool: cik_tiling_mode_table_init()+0x6ce: call without frame pointer save/setup
  drivers/gpu/drm/radeon/cik.o: warning: objtool: cik_tiling_mode_table_init()+0x72b: call without frame pointer save/setup
  ...

Both sets of warnings involve functions which have multiple switch
statements.  When there's more than one switch statement in a function,
objtool interprets all the switch jump tables as a single table.  If the
targets of one jump table assume a stack frame and the targets of
another one don't, it prints false positive warnings.

Fix the bug by detecting the size of each switch jump table.  For
multiple tables, each one ends where the next one begins.

[1] https://lkml.kernel.org/r/20160308103716.GA9618@gmail.com
[2] https://lists.01.org/pipermail/kbuild-all/2016-March/018124.html

Reported-by: Ingo Molnar 
Reported-by: kbuild test robot 
Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/2d7eecc6bc52d301f494b80f5fd62c2b6c895658.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Rename some variables and functions

2016-03-09T09:48:09+00:00

Rename some list heads to distinguish them from hash node heads, which
are added later in the patch series.

Also rename the get_*() functions to add_*(), which is more descriptive:
they "add" data to the objtool_file struct.

Also rename rodata_rela and text_rela to be clearer:
- text_rela refers to a rela entry in .rela.text.
- rodata_rela refers to a rela entry in .rela.rodata.

Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/ee0eca2bba8482aa45758958c5586c00a7b71e62.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Remove superflous INIT_LIST_HEAD

2016-03-09T09:48:08+00:00

The insns list is initialized twice, in cmd_check() and in
decode_instructions().  Remove the latter.

Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/be6e21d7eec1f072095d22a1cbe144057135e097.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Add helper macros for traversing instructions

2016-03-09T09:48:08+00:00

Add some helper macros to make it easier to traverse instructions, and
to abstract the details of the instruction list implementation in
preparation for creating a hash structure.

Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/8e1715d5035bc02b4db28d0fccef6bb1170d1f12.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Fix false positive warnings related to sibling calls

2016-03-09T09:48:08+00:00

With some configs [1], objtool prints a bunch of false positive warnings
like:

  arch/x86/events/core.o: warning: objtool: x86_del_exclusive()+0x0: frame pointer state mismatch

For some reason this config has a bunch of sibling calls.  When objtool
follows a sibling call jump, it attempts to compare the frame pointer
state.  But it also accidentally compares the FENTRY state, resulting in
a false positive warning.

[1] https://lkml.kernel.org/r/20160308154909.GA20956@gmail.com

Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/382de77ccaaa8cd79b27a155c3d109ebd4ce0219.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Compile with debugging symbols

2016-03-09T09:48:08+00:00

Compile objtool with debugging symbols ('-g') to help tools like perf
and gdb understand what it's doing.  Combined with '-O2', it's not
always helpful, but it's better than nothing.

Reported-by: Ingo Molnar 
Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/c295e9ee9ed360dc8b2e1d180c859f11cfc151ef.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Detect infinite recursion

2016-03-09T09:48:07+00:00

I don't _think_ dead_end_function() can get into a recursive loop, but
just in case, stop the loop and print a warning.

Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/ff489a63e6feb88abb192cfb361d81626dcf3e89.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Prevent infinite recursion in noreturn detection

2016-03-09T09:48:07+00:00

Ingo reported an infinite loop in objtool with a certain randconfig [1].
With the given config, two functions in crypto/ablkcipher.o contained
sibling calls to each other, which threw the recursive call in
dead_end_function() for a loop (literally!).

Split the noreturn detection into two passes.  In the first pass, check
for return instructions.  In the second pass, do the potentially
recursive sibling call check.  In most cases, the first pass will be
good enough.  In the rare case where a second pass is needed, recursion
should hopefully no longer be possible.

[1] https://lkml.kernel.org/r/20160308154909.GA20956@gmail.com

Reported-by: Ingo Molnar 
Signed-off-by: Josh Poimboeuf 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Arnaldo Carvalho de Melo 
Cc: Arnaldo Carvalho de Melo 
Cc: Bernd Petrovitsch 
Cc: Borislav Petkov 
Cc: Chris J Arges 
Cc: Jiri Slaby 
Cc: Linus Torvalds 
Cc: Michal Marek 
Cc: Namhyung Kim 
Cc: Pedro Alves 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: live-patching@vger.kernel.org
Link: http://lkml.kernel.org/r/16afb602640ef43b7782087d6cca17bf6fc13603.1457502970.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar