linux-stable.git/tools/objtool, branch v5.4.78

objtool: Support Clang non-section symbols in ORC generation

2020-11-01T11:01:01+00:00

commit e81e0724432542af8d8c702c31e9d82f57b1ff31 upstream.

When compiling the kernel with AS=clang, objtool produces a lot of
warnings:

  warning: objtool: missing symbol for section .text
  warning: objtool: missing symbol for section .init.text
  warning: objtool: missing symbol for section .ref.text

It then fails to generate the ORC table.

The problem is that objtool assumes text section symbols always exist.
But the Clang assembler is aggressive about removing them.

When generating relocations for the ORC table, objtool always tries to
reference instructions by their section symbol offset.  If the section
symbol doesn't exist, it bails.

Do a fallback: when a section symbol isn't available, reference a
function symbol instead.

Reported-by: Dmitry Golovin 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Borislav Petkov 
Tested-by: Nathan Chancellor 
Reviewed-by: Miroslav Benes 
Acked-by: Peter Zijlstra (Intel) 
Link: https://github.com/ClangBuiltLinux/linux/issues/669
Link: https://lkml.kernel.org/r/9a9cae7fcf628843aabe5a086b1a3c5bf50f42e8.1585761021.git.jpoimboe@redhat.com
Cc: Nick Desaulniers 
Signed-off-by: Greg Kroah-Hartman

objtool: Fix noreturn detection for ignored functions

2020-10-01T11:18:15+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

kbuild: support LLVM=1 to switch the default tools to Clang/LLVM

2020-08-26T08:40:47+00:00

commit a0d1c951ef08ed24f35129267e3595d86f57f5d3 upstream.

As Documentation/kbuild/llvm.rst implies, building the kernel with a
full set of LLVM tools gets very verbose and unwieldy.

Provide a single switch LLVM=1 to use Clang and LLVM tools instead
of GCC and Binutils. You can pass it from the command line or as an
environment variable.

Please note LLVM=1 does not turn on the integrated assembler. You need
to pass LLVM_IAS=1 to use it. When the upstream kernel is ready for the
integrated assembler, I think we can make it default.

We discussed what we need, and we agreed to go with a simple boolean
flag that switches both target and host tools:

  https://lkml.org/lkml/2020/3/28/494
  https://lkml.org/lkml/2020/4/3/43

Some items discussed, but not adopted:

- LLVM_DIR

  When multiple versions of LLVM are installed, I just thought supporting
  LLVM_DIR=/path/to/my/llvm/bin/ might be useful.

  CC      = $(LLVM_DIR)clang
  LD      = $(LLVM_DIR)ld.lld
    ...

  However, we can handle this by modifying PATH. So, we decided to not do
  this.

- LLVM_SUFFIX

  Some distributions (e.g. Debian) package specific versions of LLVM with
  naming conventions that use the version as a suffix.

  CC      = clang$(LLVM_SUFFIX)
  LD      = ld.lld(LLVM_SUFFIX)
    ...

  will allow a user to pass LLVM_SUFFIX=-11 to use clang-11 etc.,
  but the suffixed versions in /usr/bin/ are symlinks to binaries in
  /usr/lib/llvm-#/bin/, so this can also be handled by PATH.

Signed-off-by: Masahiro Yamada 
Reviewed-by: Nathan Chancellor 
Tested-by: Nathan Chancellor  # build
Tested-by: Nick Desaulniers 
Reviewed-by: Nick Desaulniers 
Signed-off-by: Nick Desaulniers 
Signed-off-by: Greg Kroah-Hartman

objtool: Ignore empty alternatives

2020-06-22T07:30:50+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

2020-05-14T05:58:29+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: Support Clang non-section symbols in ORC dump

2020-05-02T06:48:57+00:00

[ Upstream commit 8782e7cab51b6bf01a5a86471dd82228af1ac185 ]

Historically, the relocation symbols for ORC entries have only been
section symbols:

  .text+0: sp:sp+8 bp:(und) type:call end:0

However, the Clang assembler is aggressive about stripping section
symbols.  In that case we will need to use function symbols:

  freezing_slow_path+0: sp:sp+8 bp:(und) type:call end:0

In preparation for the generation of such entries in "objtool orc
generate", add support for reading them in "objtool orc dump".

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/b811b5eb1a42602c3b523576dc5efab9ad1c174d.1585761021.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin

objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings

2020-05-02T06:48:57+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

2020-04-23T08:36:16+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: Fix ARCH=x86_64 build error

2020-02-24T07:36:55+00:00

[ Upstream commit 8580bed7e751e6d4f17881e059daf3cb37ba4717 ]

Building objtool with ARCH=x86_64 fails with:

   $make ARCH=x86_64 -C tools/objtool
   ...
     CC       arch/x86/decode.o
   arch/x86/decode.c:10:22: fatal error: asm/insn.h: No such file or directory
    #include 
                         ^
   compilation terminated.
   mv: cannot stat ‘arch/x86/.decode.o.tmp’: No such file or directory
   make[2]: *** [arch/x86/decode.o] Error 1
   ...

The root cause is that the command-line variable 'ARCH' cannot be
overridden.  It can be replaced by 'SRCARCH', which is defined in
'tools/scripts/Makefile.arch'.

Signed-off-by: Shile Zhang 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Reviewed-by: Kamalesh Babulal 
Link: https://lore.kernel.org/r/d5d11370ae116df6c653493acd300ec3d7f5e925.1579543924.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin

objtool: Silence build output

2020-02-11T12:35:10+00:00

commit 6ec14aa7a58a1c2fb303692f8cb1ff82d9abd10a upstream.

The sync-check.sh script prints out the path due to a "cd -" at the end
of the script, even on silent builds. This isn't even needed, since the
script is executed in our build instead of sourced (so it won't change
the working directory of the surrounding build anyway).

Just remove the cd to make the build silent.

Fixes: 2ffd84ae973b ("objtool: Update sync-check.sh from perf's check-headers.sh")
Signed-off-by: Olof Johansson 
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/r/cb002857fafa8186cfb9c3e43fb62e4108a1bab9.1579543924.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman