linux-stable.git/tools/objtool/check.c, branch v4.14.331

objtool: Add a missing comma to avoid string concatenation

2023-02-06T06:46:33+00:00

commit 1fb466dff904e4a72282af336f2c355f011eec61 upstream.

Recently the kbuild robot reported two new errors:

>> lib/kunit/kunit-example-test.o: warning: objtool: .text.unlikely: unexpected end of section
>> arch/x86/kernel/dumpstack.o: warning: objtool: oops_end() falls through to next function show_opcodes()

I don't know why they did not occur in my test setup but after digging
it I realized I had accidentally dropped a comma in
tools/objtool/check.c when I renamed rewind_stack_do_exit to
rewind_stack_and_make_dead.

Add that comma back to fix objtool errors.

Link: https://lkml.kernel.org/r/202112140949.Uq5sFKR1-lkp@intel.com
Fixes: 0e25498f8cd4 ("exit: Add and use make_task_dead.")
Reported-by: kernel test robot 
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Eric Biggers 
Signed-off-by: Greg Kroah-Hartman

exit: Add and use make_task_dead.

2023-02-06T06:46:33+00:00

commit 0e25498f8cd43c1b5aa327f373dd094e9a006da7 upstream.

There are two big uses of do_exit.  The first is it's design use to be
the guts of the exit(2) system call.  The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.

Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure.  In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.

Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.

As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.

Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Eric Biggers 
Signed-off-by: Greg Kroah-Hartman

objtool: Fix noreturn detection for ignored functions

2020-10-01T11:12:49+00:00

[ Upstream commit db6c6a0df840e3f52c84cc302cc1a08ba11a4416 ]

When a function is annotated with STACK_FRAME_NON_STANDARD, objtool
doesn't validate its code paths.  It also skips sibling call detection
within the function.

But sibling call detection is actually needed for the case where the
ignored function doesn't have any return instructions.  Otherwise
objtool naively marks the function as implicit static noreturn, which
affects the reachability of its callers, resulting in "unreachable
instruction" warnings.

Fix it by just enabling sibling call detection for ignored functions.
The 'insn->ignore' check in add_jump_destinations() is no longer needed
after

  e6da9567959e ("objtool: Don't use ignore flag for fake jumps").

Fixes the following warning:

  arch/x86/kvm/vmx/vmx.o: warning: objtool: vmx_handle_exit_irqoff()+0x142: unreachable instruction

which triggers on an allmodconfig with CONFIG_GCOV_KERNEL unset.

Reported-by: Linus Torvalds 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Acked-by: Linus Torvalds 
Link: https://lkml.kernel.org/r/5b1e2536cdbaa5246b60d7791b76130a74082c62.1599751464.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin

objtool: Ignore empty alternatives

2020-06-20T08:25:07+00:00

[ Upstream commit 7170cf47d16f1ba29eca07fd818870b7af0a93a5 ]

The .alternatives section can contain entries with no original
instructions. Objtool will currently crash when handling such an entry.

Just skip that entry, but still give a warning to discourage useless
entries.

Signed-off-by: Julien Thierry 
Acked-by: Peter Zijlstra (Intel) 
Reviewed-by: Miroslav Benes 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Signed-off-by: Sasha Levin

objtool: Fix stack offset tracking for indirect CFAs

2020-05-20T06:17:01+00:00

commit d8dd25a461e4eec7190cb9d66616aceacc5110ad upstream.

When the current frame address (CFA) is stored on the stack (i.e.,
cfa->base == CFI_SP_INDIRECT), objtool neglects to adjust the stack
offset when there are subsequent pushes or pops.  This results in bad
ORC data at the end of the ENTER_IRQ_STACK macro, when it puts the
previous stack pointer on the stack and does a subsequent push.

This fixes the following unwinder warning:

  WARNING: can't dereference registers at 00000000f0a6bdba for ip interrupt_entry+0x9f/0xa0

Fixes: 627fce14809b ("objtool: Add ORC unwind table generation")
Reported-by: Vince Weaver 
Reported-by: Dave Jones 
Reported-by: Steven Rostedt 
Reported-by: Vegard Nossum 
Reported-by: Joe Mario 
Reviewed-by: Miroslav Benes 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Cc: Andy Lutomirski 
Cc: Jann Horn 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: https://lore.kernel.org/r/853d5d691b29e250333332f09b8e27410b2d9924.1587808742.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman

objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings

2020-05-02T15:24:43+00:00

[ Upstream commit bd841d6154f5f41f8a32d3c1b0bc229e326e640a ]

CONFIG_UBSAN_TRAP causes GCC to emit a UD2 whenever it encounters an
unreachable code path.  This includes __builtin_unreachable().  Because
the BUG() macro uses __builtin_unreachable() after it emits its own UD2,
this results in a double UD2.  In this case objtool rightfully detects
that the second UD2 is unreachable:

  init/main.o: warning: objtool: repair_env_string()+0x1c8: unreachable instruction

We weren't able to figure out a way to get rid of the double UD2s, so
just silence the warning.

Reported-by: Randy Dunlap 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Reviewed-by: Kees Cook 
Reviewed-by: Miroslav Benes 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/6653ad73c6b59c049211bd7c11ed3809c20ee9f5.1585761021.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin

objtool: Fix switch table detection in .text.unlikely

2020-04-24T06:01:00+00:00

commit b401efc120a399dfda1f4d2858a4de365c9b08ef upstream.

If a switch jump table's indirect branch is in a ".cold" subfunction in
.text.unlikely, objtool doesn't detect it, and instead prints a false
warning:

  drivers/media/v4l2-core/v4l2-ioctl.o: warning: objtool: v4l_print_format.cold()+0xd6: sibling call from callable instruction with modified stack frame
  drivers/hwmon/max6650.o: warning: objtool: max6650_probe.cold()+0xa5: sibling call from callable instruction with modified stack frame
  drivers/media/dvb-frontends/drxk_hard.o: warning: objtool: init_drxk.cold()+0x16f: sibling call from callable instruction with modified stack frame

Fix it by comparing the function, instead of the section and offset.

Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Reviewed-by: Miroslav Benes 
Acked-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/157c35d42ca9b6354bbb1604fe9ad7d1153ccb21.1585761021.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman

objtool: Add rewind_stack_do_exit() to the noreturn list

2019-08-09T15:53:33+00:00

commit 4fa5ecda2bf96be7464eb406df8aba9d89260227 upstream.

This fixes the following warning seen on GCC 7.3:

  arch/x86/kernel/dumpstack.o: warning: objtool: oops_end() falls through to next function show_regs()

Reported-by: kbuild test robot 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Cc: Peter Zijlstra 
Link: https://lkml.kernel.org/r/3418ebf5a5a9f6ed7e80954c741c0b904b67b5dc.1554398240.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman

objtool: Add machine_real_restart() to the noreturn list

2019-08-09T15:53:33+00:00

commit 684fb246578b9e81fc7b4ca5c71eae22edb650b2 upstream.

machine_real_restart() is annotated as '__noreturn", so add it to the
objtool noreturn list.  This fixes the following warning with clang and
CONFIG_CC_OPTIMIZE_FOR_SIZE=y:

  arch/x86/kernel/reboot.o: warning: objtool: native_machine_emergency_restart() falls through to next function machine_power_off()

Reported-by: Matthias Kaehlcke 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Thomas Gleixner 
Tested-by: Matthias Kaehlcke 
Reviewed-by: Matthias Kaehlcke 
Link: https://lkml.kernel.org/r/791712792aa4431bdd55bf1beb33a169ddf3b4a2.1529423255.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman

objtool: Support per-function rodata sections

2019-06-25T03:36:50+00:00

commit 4a60aa05a0634241ce17f957bf9fb5ac1eed6576 upstream.

Add support for processing switch jump tables in objects with multiple
.rodata sections, such as those created by '-ffunction-sections' and
'-fdata-sections'. Currently, objtool always looks in .rodata for jump
table information, which results in many "sibling call from callable
instruction with modified stack frame" warnings with objects compiled
using those flags.

The fix is comprised of three parts:

1. Flagging all .rodata sections when importing ELF information for
easier checking later.

2. Keeping a reference to the section each relocation is from in order
to get the list_head for the other relocations in that section.

3. Finding jump tables by following relocations to .rodata sections,
rather than always referencing a single global .rodata section.

The patch has been tested without data sections enabled and no
differences in the resulting orc unwind information were seen.

Note that as objtool adds terminators to end of each .text section the
unwind information generated between a function+data sections build and
a normal build aren't directly comparable. Manual inspection suggests
that objtool is now generating the correct information, or at least
making more of an effort to do so than it did previously.

Signed-off-by: Allan Xavier
Signed-off-by: Josh Poimboeuf
Signed-off-by: Thomas Gleixner
Link: https://lkml.kernel.org/r/099bdc375195c490dda04db777ee0b95d566ded1.1536325914.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman