linux.git/tools/objtool, branch v5.4.219

x86/xen: Mark cpu_bringup_and_idle() as dead_end_function

2022-05-25T07:14:38+00:00

commit 9af9dcf11bda3e2c0e24c1acaacb8685ad974e93 upstream.

The asm_cpu_bringup_and_idle() function is required to push the return
value on the stack in order to make ORC happy, but the only reason
objtool doesn't complain is because of a happy accident.

The thing is that asm_cpu_bringup_and_idle() doesn't return, so
validate_branch() never terminates and falls through to the next
function, which in the normal case is the hypercall_page. And that, as
it happens, is 4095 NOPs and a RET.

Make asm_cpu_bringup_and_idle() terminate on it's own, by making the
function it calls as a dead-end. This way we no longer rely on what
code happens to come after.

Fixes: c3881eb58d56 ("x86/xen: Make the secondary CPU idle tasks reliable")
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Juergen Gross 
Reviewed-by: Miroslav Benes 
Link: https://lore.kernel.org/r/20210624095147.693801717@infradead.org
Signed-off-by: Greg Kroah-Hartman

x86: xen: insn: Decode Xen and KVM emulate-prefix signature

2022-05-15T17:54:47+00:00

commit 4d65adfcd1196818659d3bd9b42dccab291e1751 upstream.

Decode Xen and KVM's emulate-prefix signature by x86 insn decoder.
It is called "prefix" but actually not x86 instruction prefix, so
this adds insn.emulate_prefix_size field instead of reusing
insn.prefixes.

If x86 decoder finds a special sequence of instructions of
XEN_EMULATE_PREFIX and 'ud2a; .ascii "kvm"', it just counts the
length, set insn.emulate_prefix_size and fold it with the next
instruction. In other words, the signature and the next instruction
is treated as a single instruction.

Signed-off-by: Masami Hiramatsu 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Cc: Juergen Gross 
Cc: x86@kernel.org
Cc: Boris Ostrovsky 
Cc: Ingo Molnar 
Cc: Stefano Stabellini 
Cc: Andrew Cooper 
Cc: Borislav Petkov 
Cc: xen-devel@lists.xenproject.org
Cc: Randy Dunlap 
Link: https://lkml.kernel.org/r/156777564986.25081.4964537658500952557.stgit@devnote2
[mheyne: resolved contextual conflict in tools/objtools/sync-check.sh]
Signed-off-by: Maximilian Heyne 
Signed-off-by: Greg Kroah-Hartman

objtool: Fix ".cold" section suffix check for newer versions of GCC

2021-03-04T09:26:30+00:00

[ Upstream commit 34ca59e109bdf69704c33b8eeffaa4c9f71076e5 ]

With my version of GCC 9.3.1 the ".cold" subfunctions no longer have a
numbered suffix, so the trailing period is no longer there.

Presumably this doesn't yet trigger a user-visible bug since most of the
subfunction detection logic is duplicated.   I only found it when
testing vmlinux.o validation.

Fixes: 54262aa28301 ("objtool: Fix sibling call detection")
Signed-off-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/ca0b5a57f08a2fbb48538dd915cc253b5edabb40.1611263461.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin

objtool: Fix error handling for STD/CLD warnings

2021-03-04T09:26:30+00:00

[ Upstream commit 6f567c9300a5ebd7b18c26dda1c8d6ffbdd0debd ]

Actually return an error (and display a backtrace, if requested) for
directional bit warnings.

Fixes: 2f0f9e9ad7b3 ("objtool: Add Direction Flag validation")
Signed-off-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/dc70f2adbc72f09526f7cab5b6feb8bf7f6c5ad4.1611263461.git.jpoimboe@redhat.com
Signed-off-by: Sasha Levin

objtool: Don't fail on missing symbol table

2021-02-07T14:35:49+00:00

[ Upstream commit 1d489151e9f9d1647110277ff77282fe4d96d09b ]

Thanks to a recent binutils change which doesn't generate unused
symbols, it's now possible for thunk_64.o be completely empty without
CONFIG_PREEMPTION: no text, no data, no symbols.

We could edit the Makefile to only build that file when
CONFIG_PREEMPTION is enabled, but that will likely create confusion
if/when the thunks end up getting used by some other code again.

Just ignore it and move on.

Reported-by: Nathan Chancellor 
Reviewed-by: Nathan Chancellor 
Reviewed-by: Miroslav Benes 
Tested-by: Nathan Chancellor 
Link: https://github.com/ClangBuiltLinux/linux/issues/1254
Signed-off-by: Josh Poimboeuf 
Signed-off-by: Sasha Levin

tools: Factor HOSTCC, HOSTLD, HOSTAR definitions

2021-01-30T12:54:10+00:00

commit c8a950d0d3b926a02c7b2e713850d38217cec3d1 upstream.

Several Makefiles in tools/ need to define the host toolchain variables.
Move their definition to tools/scripts/Makefile.include

Signed-off-by: Jean-Philippe Brucker 
Signed-off-by: Andrii Nakryiko 
Acked-by: Jiri Olsa 
Acked-by: Rafael J. Wysocki 
Link: https://lore.kernel.org/bpf/20201110164310.2600671-2-jean-philippe@linaro.org
Cc: Alistair Delva 
Signed-off-by: Greg Kroah-Hartman

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