linux-toradex.git/tools/objtool, branch v4.9.16

objtool: Fix bytes check of lea's rex_prefix

2016-12-06T08:20:59+00:00

For the "lea %(rsp), %rbp" case, we check if there is a rex_prefix.
But we check 'bytes' which is insn_byte_t[4] in rex_prefix (insn_field
structure). Therefore, the check is always true.

Instead, check 'nbytes' which is the right one.

Signed-off-by: Jiri Slaby 
Acked-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20161205105551.25917-1-jslaby@suse.cz
Signed-off-by: Ingo Molnar

objtool: Fix rare switch jump table pattern detection

2016-10-27T06:20:27+00:00

The following commit:

  3732710ff6f2 ("objtool: Improve rare switch jump table pattern detection")

... improved objtool's ability to detect GCC switch statement jump
tables for GCC 6.  However the check to allow short jumps with the
scanned range of instructions wasn't quite right.  The pattern detection
should allow jumps to the indirect jump instruction itself.

This fixes the following warning:

  drivers/infiniband/sw/rxe/rxe_comp.o: warning: objtool: rxe_completer()+0x315: sibling call from callable instruction with changed frame pointer

Reported-by: Arnd Bergmann 
Signed-off-by: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: 3732710ff6f2 ("objtool: Improve rare switch jump table pattern detection")
Link: http://lkml.kernel.org/r/20161026153408.2rifnw7bvoc5sex7@treble
Signed-off-by: Ingo Molnar

objtool: Skip all "unreachable instruction" warnings for gcov kernels

2016-10-16T07:12:36+00:00

Recently objtool has started reporting a few "unreachable instruction"
warnings when CONFIG_GCOV is enabled for newer versions of GCC.  Usually
this warning means there's some new control flow that objtool doesn't
understand.  But in this case, objtool is correct and the instructions
really are inaccessible.  It's an annoying quirk of gcov, but it's
harmless, so it's ok to just silence the warnings.

With older versions of GCC, it was relatively easy to detect
gcov-specific instructions and to skip any unreachable warnings produced
by them.  But GCC 6 has gotten craftier.

Instead of continuing to play whack-a-mole with gcov, just use a bigger,
more permanent hammer and disable unreachable warnings for the whole
file when gcov is enabled.  This is fine to do because a) unreachable
warnings are usually of questionable value; and b) gcov isn't used for
production kernels and we can relax the checks a bit there.

Reported-by: kbuild test robot 
Signed-off-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Arnd Bergmann 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/38d5c87d61d9cd46486dd2c86f46603dff0df86f.1476393584.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Improve rare switch jump table pattern detection

2016-10-16T07:12:35+00:00

GCC 6 added a new switch statement jump table optimization which makes
objtool's life harder.  It looks like:

  mov [rodata addr],%reg1
  ... some instructions ...
  jmpq *(%reg1,%reg2,8)

The optimization is quite rare, but objtool still needs to be able to
identify the pattern so that it can follow all possible control flow
paths related to the switch statement.

In order to detect the pattern, objtool starts from the indirect jump
and scans backwards through the function until it finds the first
instruction in the pattern.  If it encounters an unconditional jump
along the way, it stops and considers the pattern to be not found.

As it turns out, unconditional jumps can happen, as long as they are
small forward jumps within the range being scanned.

This fixes the following warnings:

  drivers/infiniband/sw/rxe/rxe_comp.o: warning: objtool: rxe_completer()+0x2f4: sibling call from callable instruction with changed frame pointer
  drivers/infiniband/sw/rxe/rxe_resp.o: warning: objtool: rxe_responder()+0x10f: sibling call from callable instruction with changed frame pointer

Reported-by: Arnd Bergmann 
Signed-off-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/8a9ed68ae1780e8d3963e4ee13f2f257fe3a3c33.1476393584.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Support '-mtune=atom' stack frame setup instruction

2016-10-11T08:35:45+00:00

Arnd reported that enabling CONFIG_MATOM results in a bunch of objtool
false positive frame pointer warnings:

  arch/x86/events/intel/ds.o: warning: objtool: intel_pmu_pebs_del()+0x43: call without frame pointer save/setup
  security/keys/keyring.o: warning: objtool: keyring_read()+0x59: call without frame pointer save/setup
  kernel/signal.o: warning: objtool: __dequeue_signal()+0xd8: call without frame pointer save/setup
  ...

objtool gets confused by the fact that the '-mtune=atom' GCC option
sometimes uses 'lea (%rsp),%rbp' instead of 'mov %rsp,%rbp'.  The
instructions are effectively the same, but objtool doesn't know about
the 'lea' variant.

Fix the false warnings by adding support for 'lea (%rsp),%rbp' in the
objtool decoder.

Reported-by: Arnd Bergmann 
Signed-off-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar

objtool: Add do_task_dead() to global noreturn list

2016-09-23T05:28:05+00:00

objtool reports the following new warning:

  kernel/exit.o: warning: objtool: do_exit() falls through to next function complete_and_exit()

The warning is caused by do_exit()'s new call to do_task_dead(), which
is a new "noreturn" function which objtool doesn't know about yet,
introduced by:

  9af6528ee9b6 ("sched/core: Optimize __schedule()")

( objtool has to know all the global noreturn functions so it can follow
  the control flow of any functions which call them.  Unfortunately they
  need to be hard-coded because there's no automated way to detect them. )

Reported-by: kbuild test robot 
Signed-off-by: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: kbuild-all@01.org
Cc: tipbuild@zytor.com
Link: http://lkml.kernel.org/r/20160922212125.zbuewckqll4yur25@treble
Signed-off-by: Ingo Molnar

Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2016-07-30T18:54:53+00:00

Pull misc fixes from Thomas Gleixner:
 "This update contains:

   - a fix for stomp-machine so the nmi_watchdog wont trigger on the cpu
     waiting for the others to execute the callback

   - various fixes and updates to objtool including an resync of the
     instruction decoder to match the kernel's decoder"

* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  objtool: Un-capitalize "Warning" for out-of-sync instruction decoder
  objtool: Resync x86 instruction decoder with the kernel's
  objtool: Support new GCC 6 switch jump table pattern
  stop_machine: Touch_nmi_watchdog() after MULTI_STOP_PREPARE
  objtool: Add 'fixdep' to objtool/.gitignore

objtool: Un-capitalize "Warning" for out-of-sync instruction decoder

2016-07-29T14:57:16+00:00

Change "Warning" to "warning" to make it look more like a GCC warning.
Hopefully that will be enough to help the 0-day bot or other automated
tools catch this warning earlier before it ends up in Linus's tree.

Reported-by: Linus Torvalds 
Signed-off-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/b1669f391a5db91040427fd9f8e1e79db18f9709.1469751119.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Resync x86 instruction decoder with the kernel's

2016-07-29T14:57:16+00:00

This fixes the following warning:

  Warning: objtool: x86 instruction decoder differs from kernel

Unfortunately we have three identical copies of the x86 instruction
decoder in the kernel tree that have to be manually kept in sync.

It's on my TODO list to at least library-ize the ones in the tools
subdir so we'd only have two of them instead of three.  In the meantime,
here's another manual sync.

Reported-by: Linus Torvalds 
Signed-off-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: c61f4d5ebaf0 ("perf tools: Add AVX-512 support to the instruction decoder used by Intel PT")
Link: http://lkml.kernel.org/r/d7f74b4d91fed25b0be33cd5c86f5131fa1a7529.1469751119.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar

objtool: Support new GCC 6 switch jump table pattern

2016-07-29T14:56:21+00:00

This fixes some false positive objtool warnings seen with gcc 6.1.1:

  kernel/trace/ring_buffer.o: warning: objtool: ring_buffer_read_page()+0x36c: sibling call from callable instruction with changed frame pointer
  arch/x86/kernel/reboot.o: warning: objtool: native_machine_emergency_restart()+0x139: sibling call from callable instruction with changed frame pointer
  lib/xz/xz_dec_stream.o: warning: objtool: xz_dec_run()+0xc2: sibling call from callable instruction with changed frame pointer

With GCC 6, a new code pattern is sometimes used to access a switch
statement jump table in .rodata, which objtool doesn't yet recognize:

  mov [rodata addr],%reg1
  ... some instructions ...
  jmpq *(%reg1,%reg2,8)

Add support for detecting that pattern.  The detection code is rather
crude, but it's still effective at weeding out false positives and
catching real warnings.  It can be refined later once objtool starts
reading DWARF CFI.

Reported-by: Linus Torvalds 
Signed-off-by: Josh Poimboeuf 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/b8c9503b4ad8c8a827cc5400db4c1b40a3ea07bc.1469751119.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar