objtool: fix build failure due to missing libopcodes check

Commit 59953303827e ("objtool: Disassemble code with libopcodes instead
of running objdump") added support for using libopcodes for disasse

objtool: fix build failure due to missing libopcodes check

Commit 59953303827e ("objtool: Disassemble code with libopcodes instead
of running objdump") added support for using libopcodes for disassembly.
However, the feature detection checks for libbfd availability but then
unconditionally links against libopcodes:

ifeq ($(feature-libbfd),1)
OBJTOOL_LDFLAGS += -lopcodes
endif

This causes build failures in environments where libbfd is installed but
libopcodes is not, since the test-libbfd.c feature test only links
against -lbfd and -ldl, not -lopcodes:

/usr/bin/ld: cannot find -lopcodes: No such file or directory
collect2: error: ld returned 1 exit status
make[4]: *** [Makefile:109: objtool] Error 1

Additionally, the shared feature framework uses $(CC) which is the
cross-compiler in cross-compilation builds. Since objtool is a host tool
that links with $(HOSTCC) against host libraries, the feature detection
can falsely report libopcodes as available when the cross-compiler's
sysroot has it but the host system doesn't.

Fix this by replacing the feature framework check with a direct inline
test that uses $(HOSTCC) to compile and link a test program against
libopcodes, similar to how xxhash availability is detected.

Fixes: 59953303827e ("objtool: Disassemble code with libopcodes instead of running objdump")
Assisted-by: claude-opus-4-5-20251101
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251223120357.2492008-1-sashal@kernel.org

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objtool: Build with disassembly can fail when including bdf.h

Building objtool with disassembly support can fail when including
the bdf.h file:

In file included from tools/objtool/include/objtool

objtool: Build with disassembly can fail when including bdf.h

Building objtool with disassembly support can fail when including
the bdf.h file:

In file included from tools/objtool/include/objtool/arch.h:108,
from check.c:14:
/usr/include/bfd.h:35:2: error: #error config.h must be included before this header
35 | #error config.h must be included before this header
| ^~~~~

This check is present in the bfd.h file generated from the binutils
source code, but it is not necessarily present in the bfd.h file
provided in a binutil package (for example, it is not present in
the binutil RPM).

The solution to this issue is to define the PACKAGE macro before
including bfd.h. This is the solution suggested by the binutil
developer in bug 14243, and it is used by other kernel tools
which also use bfd.h (perf and bpf).

Fixes: 59953303827ec ("objtool: Disassemble code with libopcodes instead of running objdump")
Closes: https://lore.kernel.org/all/3fa261fd-3b46-4cbe-b48d-7503aabc96cb@oracle.com/
Reported-by: Nathan Chancellor <nathan@kernel.org>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=14243
Link: https://patch.msgid.link/20251126134519.1760889-1-alexandre.chartre@oracle.com

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objtool: Add Function to get the name of a CPU feature

Add a function to get the name of a CPU feature. The function is
architecture dependent and currently only implemented for x86. The
feature nam

objtool: Add Function to get the name of a CPU feature

Add a function to get the name of a CPU feature. The function is
architecture dependent and currently only implemented for x86. The
feature names are automatically generated from the cpufeatures.h
include file.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://patch.msgid.link/20251121095340.464045-27-alexandre.chartre@oracle.com

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objtool: Disassemble code with libopcodes instead of running objdump

objtool executes the objdump command to disassemble code. Use libopcodes
instead to have more control about the disassembly scope

objtool: Disassemble code with libopcodes instead of running objdump

objtool executes the objdump command to disassemble code. Use libopcodes
instead to have more control about the disassembly scope and output.
If libopcodes is not present then objtool is built without disassembly
support.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://patch.msgid.link/20251121095340.464045-4-alexandre.chartre@oracle.com

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objtool: Set minimum xxhash version to 0.8

XXH3 is only supported starting with xxhash 0.8. Enforce that.

Fixes: 0d83da43b1e1 ("objtool/klp: Add --checksum option to generate per-function checksum

objtool: Set minimum xxhash version to 0.8

XXH3 is only supported starting with xxhash 0.8. Enforce that.

Fixes: 0d83da43b1e1 ("objtool/klp: Add --checksum option to generate per-function checksums")
Closes: https://lore.kernel.org/SN6PR02MB41579B83CD295C9FEE40EED6D4FCA@SN6PR02MB4157.namprd02.prod.outlook.com
Reported-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Link: https://patch.msgid.link/7227c94692a3a51840278744c7af31b4797c6b96.1762990139.git.jpoimboe@kernel.org

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objtool/klp: Introduce klp diff subcommand for diffing object files

Add a new klp diff subcommand which performs a binary diff between two
object files and extracts changed functions into a new obje

objtool/klp: Introduce klp diff subcommand for diffing object files

Add a new klp diff subcommand which performs a binary diff between two
object files and extracts changed functions into a new object which can
then be linked into a livepatch module.

This builds on concepts from the longstanding out-of-tree kpatch [1]
project which began in 2012 and has been used for many years to generate
livepatch modules for production kernels. However, this is a complete
rewrite which incorporates hard-earned lessons from 12+ years of
maintaining kpatch.

Key improvements compared to kpatch-build:

- Integrated with objtool: Leverages objtool's existing control-flow
graph analysis to help detect changed functions.

- Works on vmlinux.o: Supports late-linked objects, making it
compatible with LTO, IBT, and similar.

- Simplified code base: ~3k fewer lines of code.

- Upstream: No more out-of-tree #ifdef hacks, far less cruft.

- Cleaner internals: Vastly simplified logic for symbol/section/reloc
inclusion and special section extraction.

- Robust __LINE__ macro handling: Avoids false positive binary diffs
caused by the __LINE__ macro by introducing a fix-patch-lines script
(coming in a later patch) which injects #line directives into the
source .patch to preserve the original line numbers at compile time.

Note the end result of this subcommand is not yet functionally complete.
Livepatch needs some ELF magic which linkers don't like:

- Two relocation sections (.rela*, .klp.rela*) for the same text
section.

- Use of SHN_LIVEPATCH to mark livepatch symbols.

Unfortunately linkers tend to mangle such things. To work around that,
klp diff generates a linker-compliant intermediate binary which encodes
the relevant KLP section/reloc/symbol metadata.

After module linking, a klp post-link step (coming soon) will clean up
the mess and convert the linked .ko into a fully compliant livepatch
module.

Note this subcommand requires the diffed binaries to have been compiled
with -ffunction-sections and -fdata-sections, and processed with
'objtool --checksum'. Those constraints will be handled by a klp-build
script introduced in a later patch.

Without '-ffunction-sections -fdata-sections', reliable object diffing
would be infeasible due to toolchain limitations:

- For intra-file+intra-section references, the compiler might
occasionally generated hard-coded instruction offsets instead of
relocations.

- Section-symbol-based references can be ambiguous:

- Overlapping or zero-length symbols create ambiguity as to which
symbol is being referenced.

- A reference to the end of a symbol (e.g., checking array bounds)
can be misinterpreted as a reference to the next symbol, or vice
versa.

A potential future alternative to '-ffunction-sections -fdata-sections'
would be to introduce a toolchain option that forces symbol-based
(non-section) relocations.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

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objtool/klp: Add --checksum option to generate per-function checksums

In preparation for the objtool klp diff subcommand, add a command-line
option to generate a unique checksum for each function.

objtool/klp: Add --checksum option to generate per-function checksums

In preparation for the objtool klp diff subcommand, add a command-line
option to generate a unique checksum for each function. This will
enable detection of functions which have changed between two versions of
an object file.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

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objtool: Clean up compiler flag usage

KBUILD_HOSTCFLAGS and KBUILD_HOSTLDFLAGS aren't defined when objtool is
built standalone. Also, the EXTRA_WARNINGS flags are rather arbitrary.

Make things sim

objtool: Clean up compiler flag usage

KBUILD_HOSTCFLAGS and KBUILD_HOSTLDFLAGS aren't defined when objtool is
built standalone. Also, the EXTRA_WARNINGS flags are rather arbitrary.

Make things simpler and more consistent by specifying compiler flags
explicitly and tweaking the warnings. Also make a few code tweaks to
make the new warnings happy.

Acked-by: Petr Mladek <pmladek@suse.com>
Tested-by: Joe Lawrence <joe.lawrence@redhat.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

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objtool: Hide unnecessary compiler error message

The check for using old libelf prints an error message when libelf.h is
not available but does not abort. This may confuse so hide the compiler
error

objtool: Hide unnecessary compiler error message

The check for using old libelf prints an error message when libelf.h is
not available but does not abort. This may confuse so hide the compiler
error message.

Signed-off-by: David Engraf <david.engraf@sysgo.com>
Link: https://lore.kernel.org/r/20250203073610.206000-1-david.engraf@sysgo.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

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tools: Remove redundant quiet setup

Q is exported from Makefile.include so it is not necessary to manually
set it.

Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Charlie Jenkins <charlie@

tools: Remove redundant quiet setup

Q is exported from Makefile.include so it is not necessary to manually
set it.

Reviewed-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <qmo@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Benjamin Tissoires <bentiss@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Eduard Zingerman <eddyz87@gmail.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Lukasz Luba <lukasz.luba@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: Mykola Lysenko <mykolal@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Song Liu <song@kernel.org>
Cc: Stanislav Fomichev <sdf@google.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Zhang Rui <rui.zhang@intel.com>
Link: https://lore.kernel.org/r/20250213-quiet_tools-v3-2-07de4482a581@rivosinc.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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objtool: Also include tools/include/uapi

When building objtool against a sysroot that contains a stripped down
version of the UAPI headers, the following error happens:

In file included from ar

objtool: Also include tools/include/uapi

When building objtool against a sysroot that contains a stripped down
version of the UAPI headers, the following error happens:

In file included from arch/x86/decode.c:10:
In file included from .../tools/arch/x86/include/asm/insn.h:10:
In file included from <sysroot>/include/asm/byteorder.h:9:
In file included from <sysroot>/include/linux/byteorder/little_endian.h:15:
In file included from <sysroot>/include/linux/stddef.h:9:
In file included from .../tools/include/linux/compiler_types.h:36:
.../tools/include/linux/compiler-gcc.h:3:2: error: "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
3 | #error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
| ^
1 error generated.

As hinted by the error, this is because <sysroot>/include/linux/stddef.h
(a stripped-down version of uapi/include/linux/stddef.h) includes
linux/compiler_types.h directly. However, this gets resolved to
tools/include/linux/compiler_types.h, which is not expected to be
included directly.

To resolve this, I added tools/include/uapi to the include paths when
building objtool. With this trick, linux/stddef.h is resolved to
tools/include/uapi/linux/stddef.h, which doesn't include
linux/compiler_types.h.

Signed-off-by: HONG Yifan <elsk@google.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

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objtool/LoongArch: Enable orc to be built

Implement arch-specific init_orc_entry(), write_orc_entry(), reg_name(),
orc_type_name(), print_reg() and orc_print_dump(), then set BUILD_ORC as
y to build

objtool/LoongArch: Enable orc to be built

Implement arch-specific init_orc_entry(), write_orc_entry(), reg_name(),
orc_type_name(), print_reg() and orc_print_dump(), then set BUILD_ORC as
y to build the orc related files.

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Co-developed-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

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objtool: Fix HOSTCC flag usage

HOSTCC is always wanted when building objtool. Setting CC to HOSTCC
happens after tools/scripts/Makefile.include is included, meaning
flags (like CFLAGS) are set assum

objtool: Fix HOSTCC flag usage

HOSTCC is always wanted when building objtool. Setting CC to HOSTCC
happens after tools/scripts/Makefile.include is included, meaning
flags (like CFLAGS) are set assuming say CC is gcc, but then it can be
later set to HOSTCC which may be clang. tools/scripts/Makefile.include
is needed for host set up and common macros in objtool's
Makefile. Rather than override the CC variable to HOSTCC, just pass CC
as HOSTCC to the sub-makes of Makefile.build, the libsubcmd builds and
also to the linkage step.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20230126190606.40739-4-irogers@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

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objtool: Properly support make V=1

The Q variable was being used but never correctly set up. Add the
setting up and use in place of @.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://l

objtool: Properly support make V=1

The Q variable was being used but never correctly set up. Add the
setting up and use in place of @.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20230126190606.40739-3-irogers@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

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objtool: Install libsubcmd in build

Including from tools/lib can create inadvertent dependencies. Install
libsubcmd in the objtool build and then include the headers from
there.

Signed-off-by: Ian

objtool: Install libsubcmd in build

Including from tools/lib can create inadvertent dependencies. Install
libsubcmd in the objtool build and then include the headers from
there.

Signed-off-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20230126190606.40739-2-irogers@google.com
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>

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Merge tag 'kbuild-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

- Add HOSTPKG_CONFIG env variable to allow users to overr

Merge tag 'kbuild-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

- Add HOSTPKG_CONFIG env variable to allow users to override pkg-config

- Support W=e as a shorthand for KCFLAGS=-Werror

- Fix CONFIG_IKHEADERS build to support toybox cpio

- Add scripts/dummy-tools/pahole to ease distro packagers' life

- Suppress false-positive warnings from checksyscalls.sh for W=2 build

- Factor out the common code of arch/*/boot/install.sh into
scripts/install.sh

- Support 'kernel-install' tool in scripts/prune-kernel

- Refactor module-versioning to link the symbol versions at the final
link of vmlinux and modules

- Remove CONFIG_MODULE_REL_CRCS because module-versioning now works in
an arch-agnostic way

- Refactor modpost, Makefiles

* tag 'kbuild-v5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (56 commits)
genksyms: adjust the output format to modpost
kbuild: stop merging *.symversions
kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS
modpost: extract symbol versions from *.cmd files
modpost: add sym_find_with_module() helper
modpost: change the license of EXPORT_SYMBOL to bool type
modpost: remove left-over cross_compile declaration
kbuild: record symbol versions in *.cmd files
kbuild: generate a list of objects in vmlinux
modpost: move *.mod.c generation to write_mod_c_files()
modpost: merge add_{intree_flag,retpoline,staging_flag} to add_header
scripts/prune-kernel: Use kernel-install if available
kbuild: factor out the common installation code into scripts/install.sh
modpost: split new_symbol() to symbol allocation and hash table addition
modpost: make sym_add_exported() always allocate a new symbol
modpost: make multiple export error
modpost: dump Module.symvers in the same order of modules.order
modpost: traverse the namespace_list in order
modpost: use doubly linked list for dump_lists
modpost: traverse unresolved symbols in order
...

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objtool: Remove libsubcmd.a when make clean

The file libsubcmd.a still exists after make clean, remove it.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimbo

objtool: Remove libsubcmd.a when make clean

The file libsubcmd.a still exists after make clean, remove it.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/1652258270-6278-3-git-send-email-yangtiezhu@loongson.cn

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objtool: Remove inat-tables.c when make clean

When build objtool on x86, the generated file inat-tables.c is in
arch/x86/lib instead of arch/x86, use the correct dir to remove it
when make clean.

$

objtool: Remove inat-tables.c when make clean

When build objtool on x86, the generated file inat-tables.c is in
arch/x86/lib instead of arch/x86, use the correct dir to remove it
when make clean.

$ cd tools/objtool
$ make
[...]
GEN arch/x86/lib/inat-tables.c
[...]

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/1652258270-6278-2-git-send-email-yangtiezhu@loongson.cn

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objtool: Ditch subcommands

Objtool has a fairly singular focus. It runs on object files and does
validations and transformations which can be combined in various ways.
The subcommand model has neve

objtool: Ditch subcommands

Objtool has a fairly singular focus. It runs on object files and does
validations and transformations which can be combined in various ways.
The subcommand model has never been a good fit, making it awkward to
combine and remove options.

Remove the "check" and "orc" subcommands in favor of a more traditional
cmdline option model. This makes it much more flexible to use, and
easier to port individual features to other arches.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Link: https://lkml.kernel.org/r/5c61ebf805e90aefc5fa62bc63468ffae53b9df6.1650300597.git.jpoimboe@redhat.com

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kbuild: Allow kernel installation packaging to override pkg-config

Add HOSTPKG_CONFIG to allow tooling that builds the kernel to override
what pkg-config and parameters are used.

Signed-off-by: Chu

kbuild: Allow kernel installation packaging to override pkg-config

Add HOSTPKG_CONFIG to allow tooling that builds the kernel to override
what pkg-config and parameters are used.

Signed-off-by: Chun-Tse Shao <ctshao@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

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kbuild: replace $(if A,A,B) with $(or A,B)

$(or ...) is available since GNU Make 3.81, and useful to shorten the
code in some places.

Covert as follows:

$(if A,A,B) --> $(or A,B)

This patch a

kbuild: replace $(if A,A,B) with $(or A,B)

$(or ...) is available since GNU Make 3.81, and useful to shorten the
code in some places.

Covert as follows:

$(if A,A,B) --> $(or A,B)

This patch also converts:

$(if A, A, B) --> $(or A, B)

Strictly speaking, the latter is not an equivalent conversion because
GNU Make keeps spaces after commas; if A is not empty, $(if A, A, B)
expands to " A", while $(or A, B) expands to "A".

Anyway, preceding spaces are not significant in the code hunks I touched.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

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objtool: Refactor ORC section generation

Decouple ORC entries from instructions. This simplifies the
control/data flow, and is going to make it easier to support alternative
instructions which chan

objtool: Refactor ORC section generation

Decouple ORC entries from instructions. This simplifies the
control/data flow, and is going to make it easier to support alternative
instructions which change the stack layout.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

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objtool: Rework header include paths

Currently objtool headers are being included either by their base name
or included via ../ from a parent directory. In case of a base name usage:

#include "war

objtool: Rework header include paths

Currently objtool headers are being included either by their base name
or included via ../ from a parent directory. In case of a base name usage:

#include "warn.h"
#include "arch_elf.h"

it does not make it apparent from which directory the file comes from.
To make it slightly better, and actually to avoid name clashes some arch
specific files have "arch_" suffix. And files from an arch folder have
to revert to including via ../ e.g:
#include "../../elf.h"

With additional architectures support and the code base growth there is
a need for clearer headers naming scheme for multiple reasons:
1. to make it instantly obvious where these files come from (objtool
itself / objtool arch|generic folders / some other external files),
2. to avoid name clashes of objtool arch specific headers, potential
obtool arch generic headers and the system header files (there is
/usr/include/elf.h already),
3. to avoid ../ includes and improve code readability.
4. to give a warm fuzzy feeling to developers who are mostly kernel
developers and are accustomed to linux kernel headers arranging
scheme.

Doesn't this make it instantly obvious where are these files come from?

#include <objtool/warn.h>
#include <arch/elf.h>

And doesn't it look nicer to avoid ugly ../ includes? Which also
guarantees this is elf.h from the objtool and not /usr/include/elf.h.

#include <objtool/elf.h>

This patch defines and implements new objtool headers arranging
scheme. Which is:
- all generic headers go to include/objtool (similar to include/linux)
- all arch headers go to arch/$(SRCARCH)/include/arch (to get arch
prefix). This is similar to linux arch specific "asm/*" headers but we
are not abusing "asm" name and calling it what it is. This also helps
to prevent name clashes (arch is not used in system headers or kernel
exports).

To bring objtool to this state the following things are done:
1. current top level tools/objtool/ headers are moved into
include/objtool/ subdirectory,
2. arch specific headers, currently only arch/x86/include/ are moved into
arch/x86/include/arch/ and were stripped of "arch_" suffix,
3. new -I$(srctree)/tools/objtool/include include path to make
includes like <objtool/warn.h> possible,
4. rewriting file includes,
5. make git not to ignore include/objtool/ subdirectory.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

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tools: Factor HOSTCC, HOSTLD, HOSTAR definitions

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

Signed-off-by: Jean

tools: Factor HOSTCC, HOSTLD, HOSTAR definitions

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 <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/bpf/20201110164310.2600671-2-jean-philippe@linaro.org

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objtool: Allow nested externs to enable BUILD_BUG()

Currently BUILD_BUG() macro is expanded to smth like the following:
do {
extern void __compiletime_assert_0(void)

objtool: Allow nested externs to enable BUILD_BUG()

Currently BUILD_BUG() macro is expanded to smth like the following:
do {
extern void __compiletime_assert_0(void)
__attribute__((error("BUILD_BUG failed")));
if (!(!(1)))
__compiletime_assert_0();
} while (0);

If used in a function body this obviously would produce build errors
with -Wnested-externs and -Werror.

Build objtool with -Wno-nested-externs to enable BUILD_BUG() usage.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>

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