Since commit bede169618 ("kbuild: enable objtool for *.mod.o and
additional kernel objects"), Clang LTO builds do not perform any
optimizations when CONFIG_OBJTOOL is disabled (e.g., for ARCH=arm64).
This is because every LLVM bitcode file is immediately converted to
ELF format before the object files are linked together.
This commit fixes the breakage.
Fixes: bede169618 ("kbuild: enable objtool for *.mod.o and additional kernel objects")
Reported-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Due to the fact that runtime const ELF sections are named without a
leading period or double underscore, the RSTRIP logic that removes the
static RELA sections from vmlinux fails to identify them. This results
in a situation like below, where some sections that were supposed to get
removed are left behind.
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[58] runtime_shift_d_hash_shift PROGBITS ffffffff83500f50 2900f50 000014 00 A 0 0 1
[59] .relaruntime_shift_d_hash_shift RELA 0000000000000000 55b6f00 000078 18 I 70 58 8
[60] runtime_ptr_dentry_hashtable PROGBITS ffffffff83500f68 2900f68 000014 00 A 0 0 1
[61] .relaruntime_ptr_dentry_hashtable RELA 0000000000000000 55b6f78 000078 18 I 70 60 8
[62] runtime_ptr_USER_PTR_MAX PROGBITS ffffffff83500f80 2900f80 000238 00 A 0 0 1
[63] .relaruntime_ptr_USER_PTR_MAX RELA 0000000000000000 55b6ff0 000d50 18 I 70 62 8
So tweak the match expression to strip all sections starting with .rel.
While at it, consolidate the logic used by RISC-V, s390 and x86 into a
single shared Makefile library command.
Link: https://lore.kernel.org/all/CAHk-=wjk3ynjomNvFN8jf9A1k=qSc=JFF591W00uXj-qqNUxPQ@mail.gmail.com/
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Charlie Jenkins <charlie@rivosinc.com>
Tested-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Replace lz4c with lz4 for kernel image compression.
Although lz4 and lz4c are functionally similar, lz4c has been deprecated
upstream since 2018. Since as early as Ubuntu 16.04 and Fedora 25, lz4
and lz4c have been packaged together, making it safe to update the
requirement from lz4c to lz4.
Consequently, some distributions and build systems, such as OpenEmbedded,
have fully transitioned to using lz4. OpenEmbedded core adopted this
change in commit fe167e082cbd ("bitbake.conf: require lz4 instead of
lz4c"), causing compatibility issues when building the mainline kernel
in the latest OpenEmbedded environment, as seen in the errors below.
This change also updates the LZ4 compression commands to make it backward
compatible by replacing stdin and stdout with the '-' option, due to some
unclear reason, the stdout keyword does not work for lz4 and '-' works for
both. In addition, this modifies the legacy '-c1' with '-9' which is also
compatible with both. This fixes the mainline kernel build failures with
the latest master OpenEmbedded builds associated with the mentioned
compatibility issues.
LZ4 arch/arm/boot/compressed/piggy_data
/bin/sh: 1: lz4c: not found
...
...
ERROR: oe_runmake failed
Link: https://github.com/lz4/lz4/pull/553
Suggested-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Signed-off-by: Parth Pancholi <parth.pancholi@toradex.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Currently, objtool is disabled in scripts/Makefile.{modfinal,vmlinux}.
This commit moves rule_cc_o_c and rule_as_o_S to scripts/Makefile.lib
and set objtool-enabled to y there.
With this change, *.mod.o, .module-common.o, builtin-dtb.o, and
vmlinux.export.o will now be covered by objtool.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The cmd_cc_o_c and cmd_as_o_S macros are duplicated in
scripts/Makefile.{build,modfinal,vmlinux}.
This commit factors them out to scripts/Makefile.lib.
No functional changes are intended.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
There has been a long-standing request to support building external
modules in a separate build directory.
This commit introduces a new environment variable, KBUILD_EXTMOD_OUTPUT,
and its shorthand Make variable, MO.
A simple usage:
$ make -C <kernel-dir> M=<module-src-dir> MO=<module-build-dir>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Add the build support for using Clang's Propeller optimizer. Like
AutoFDO, Propeller uses hardware sampling to gather information
about the frequency of execution of different code paths within a
binary. This information is then used to guide the compiler's
optimization decisions, resulting in a more efficient binary.
The support requires a Clang compiler LLVM 19 or later, and the
create_llvm_prof tool
(https://github.com/google/autofdo/releases/tag/v0.30.1). This
commit is limited to x86 platforms that support PMU features
like LBR on Intel machines and AMD Zen3 BRS.
Here is an example workflow for building an AutoFDO+Propeller
optimized kernel:
1) Build the kernel on the host machine, with AutoFDO and Propeller
build config
CONFIG_AUTOFDO_CLANG=y
CONFIG_PROPELLER_CLANG=y
then
$ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile>
“<autofdo_profile>” is the profile collected when doing a non-Propeller
AutoFDO build. This step builds a kernel that has the same optimization
level as AutoFDO, plus a metadata section that records basic block
information. This kernel image runs as fast as an AutoFDO optimized
kernel.
2) Install the kernel on test/production machines.
3) Run the load tests. The '-c' option in perf specifies the sample
event period. We suggest using a suitable prime number,
like 500009, for this purpose.
For Intel platforms:
$ perf record -e BR_INST_RETIRED.NEAR_TAKEN:k -a -N -b -c <count> \
-o <perf_file> -- <loadtest>
For AMD platforms:
The supported system are: Zen3 with BRS, or Zen4 with amd_lbr_v2
# To see if Zen3 support LBR:
$ cat proc/cpuinfo | grep " brs"
# To see if Zen4 support LBR:
$ cat proc/cpuinfo | grep amd_lbr_v2
# If the result is yes, then collect the profile using:
$ perf record --pfm-events RETIRED_TAKEN_BRANCH_INSTRUCTIONS:k -a \
-N -b -c <count> -o <perf_file> -- <loadtest>
4) (Optional) Download the raw perf file to the host machine.
5) Generate Propeller profile:
$ create_llvm_prof --binary=<vmlinux> --profile=<perf_file> \
--format=propeller --propeller_output_module_name \
--out=<propeller_profile_prefix>_cc_profile.txt \
--propeller_symorder=<propeller_profile_prefix>_ld_profile.txt
“create_llvm_prof” is the profile conversion tool, and a prebuilt
binary for linux can be found on
https://github.com/google/autofdo/releases/tag/v0.30.1 (can also build
from source).
"<propeller_profile_prefix>" can be something like
"/home/user/dir/any_string".
This command generates a pair of Propeller profiles:
"<propeller_profile_prefix>_cc_profile.txt" and
"<propeller_profile_prefix>_ld_profile.txt".
6) Rebuild the kernel using the AutoFDO and Propeller profile files.
CONFIG_AUTOFDO_CLANG=y
CONFIG_PROPELLER_CLANG=y
and
$ make LLVM=1 CLANG_AUTOFDO_PROFILE=<autofdo_profile> \
CLANG_PROPELLER_PROFILE_PREFIX=<propeller_profile_prefix>
Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Suggested-by: Stephane Eranian <eranian@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Add the build support for using Clang's AutoFDO. Building the kernel
with AutoFDO does not reduce the optimization level from the
compiler. AutoFDO uses hardware sampling to gather information about
the frequency of execution of different code paths within a binary.
This information is then used to guide the compiler's optimization
decisions, resulting in a more efficient binary. Experiments
showed that the kernel can improve up to 10% in latency.
The support requires a Clang compiler after LLVM 17. This submission
is limited to x86 platforms that support PMU features like LBR on
Intel machines and AMD Zen3 BRS. Support for SPE on ARM 1,
and BRBE on ARM 1 is part of planned future work.
Here is an example workflow for AutoFDO kernel:
1) Build the kernel on the host machine with LLVM enabled, for example,
$ make menuconfig LLVM=1
Turn on AutoFDO build config:
CONFIG_AUTOFDO_CLANG=y
With a configuration that has LLVM enabled, use the following
command:
scripts/config -e AUTOFDO_CLANG
After getting the config, build with
$ make LLVM=1
2) Install the kernel on the test machine.
3) Run the load tests. The '-c' option in perf specifies the sample
event period. We suggest using a suitable prime number,
like 500009, for this purpose.
For Intel platforms:
$ perf record -e BR_INST_RETIRED.NEAR_TAKEN:k -a -N -b -c <count> \
-o <perf_file> -- <loadtest>
For AMD platforms:
The supported system are: Zen3 with BRS, or Zen4 with amd_lbr_v2
For Zen3:
$ cat proc/cpuinfo | grep " brs"
For Zen4:
$ cat proc/cpuinfo | grep amd_lbr_v2
$ perf record --pfm-events RETIRED_TAKEN_BRANCH_INSTRUCTIONS:k -a \
-N -b -c <count> -o <perf_file> -- <loadtest>
4) (Optional) Download the raw perf file to the host machine.
5) To generate an AutoFDO profile, two offline tools are available:
create_llvm_prof and llvm_profgen. The create_llvm_prof tool is part
of the AutoFDO project and can be found on GitHub
(https://github.com/google/autofdo), version v0.30.1 or later. The
llvm_profgen tool is included in the LLVM compiler itself. It's
important to note that the version of llvm_profgen doesn't need to
match the version of Clang. It needs to be the LLVM 19 release or
later, or from the LLVM trunk.
$ llvm-profgen --kernel --binary=<vmlinux> --perfdata=<perf_file> \
-o <profile_file>
or
$ create_llvm_prof --binary=<vmlinux> --profile=<perf_file> \
--format=extbinary --out=<profile_file>
Note that multiple AutoFDO profile files can be merged into one via:
$ llvm-profdata merge -o <profile_file> <profile_1> ... <profile_n>
6) Rebuild the kernel using the AutoFDO profile file with the same config
as step 1, (Note CONFIG_AUTOFDO_CLANG needs to be enabled):
$ make LLVM=1 CLANG_AUTOFDO_PROFILE=<profile_file>
Co-developed-by: Han Shen <shenhan@google.com>
Signed-off-by: Han Shen <shenhan@google.com>
Signed-off-by: Rong Xu <xur@google.com>
Suggested-by: Sriraman Tallam <tmsriram@google.com>
Suggested-by: Krzysztof Pszeniczny <kpszeniczny@google.com>
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Suggested-by: Stephane Eranian <eranian@google.com>
Tested-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Yabin Cui <yabinc@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Tested-by: Peter Jung <ptr1337@cachyos.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Pull Rust updates from Miguel Ojeda:
"Toolchain and infrastructure:
- Support 'MITIGATION_{RETHUNK,RETPOLINE,SLS}' (which cleans up
objtool warnings), teach objtool about 'noreturn' Rust symbols and
mimic '___ADDRESSABLE()' for 'module_{init,exit}'. With that, we
should be objtool-warning-free, so enable it to run for all Rust
object files.
- KASAN (no 'SW_TAGS'), KCFI and shadow call sanitizer support.
- Support 'RUSTC_VERSION', including re-config and re-build on
change.
- Split helpers file into several files in a folder, to avoid
conflicts in it. Eventually those files will be moved to the right
places with the new build system. In addition, remove the need to
manually export the symbols defined there, reusing existing
machinery for that.
- Relax restriction on configurations with Rust + GCC plugins to just
the RANDSTRUCT plugin.
'kernel' crate:
- New 'list' module: doubly-linked linked list for use with reference
counted values, which is heavily used by the upcoming Rust Binder.
This includes 'ListArc' (a wrapper around 'Arc' that is guaranteed
unique for the given ID), 'AtomicTracker' (tracks whether a
'ListArc' exists using an atomic), 'ListLinks' (the prev/next
pointers for an item in a linked list), 'List' (the linked list
itself), 'Iter' (an iterator over a 'List'), 'Cursor' (a cursor
into a 'List' that allows to remove elements), 'ListArcField' (a
field exclusively owned by a 'ListArc'), as well as support for
heterogeneous lists.
- New 'rbtree' module: red-black tree abstractions used by the
upcoming Rust Binder.
This includes 'RBTree' (the red-black tree itself), 'RBTreeNode' (a
node), 'RBTreeNodeReservation' (a memory reservation for a node),
'Iter' and 'IterMut' (immutable and mutable iterators), 'Cursor'
(bidirectional cursor that allows to remove elements), as well as
an entry API similar to the Rust standard library one.
- 'init' module: add 'write_[pin_]init' methods and the
'InPlaceWrite' trait. Add the 'assert_pinned!' macro.
- 'sync' module: implement the 'InPlaceInit' trait for 'Arc' by
introducing an associated type in the trait.
- 'alloc' module: add 'drop_contents' method to 'BoxExt'.
- 'types' module: implement the 'ForeignOwnable' trait for
'Pin<Box<T>>' and improve the trait's documentation. In addition,
add the 'into_raw' method to the 'ARef' type.
- 'error' module: in preparation for the upcoming Rust support for
32-bit architectures, like arm, locally allow Clippy lint for
those.
Documentation:
- https://rust.docs.kernel.org has been announced, so link to it.
- Enable rustdoc's "jump to definition" feature, making its output a
bit closer to the experience in a cross-referencer.
- Debian Testing now also provides recent Rust releases (outside of
the freeze period), so add it to the list.
MAINTAINERS:
- Trevor is joining as reviewer of the "RUST" entry.
And a few other small bits"
* tag 'rust-6.12' of https://github.com/Rust-for-Linux/linux: (54 commits)
kasan: rust: Add KASAN smoke test via UAF
kbuild: rust: Enable KASAN support
rust: kasan: Rust does not support KHWASAN
kbuild: rust: Define probing macros for rustc
kasan: simplify and clarify Makefile
rust: cfi: add support for CFI_CLANG with Rust
cfi: add CONFIG_CFI_ICALL_NORMALIZE_INTEGERS
rust: support for shadow call stack sanitizer
docs: rust: include other expressions in conditional compilation section
kbuild: rust: replace proc macros dependency on `core.o` with the version text
kbuild: rust: rebuild if the version text changes
kbuild: rust: re-run Kconfig if the version text changes
kbuild: rust: add `CONFIG_RUSTC_VERSION`
rust: avoid `box_uninit_write` feature
MAINTAINERS: add Trevor Gross as Rust reviewer
rust: rbtree: add `RBTree::entry`
rust: rbtree: add cursor
rust: rbtree: add mutable iterator
rust: rbtree: add iterator
rust: rbtree: add red-black tree implementation backed by the C version
...
Pull Kbuild updates from Masahiro Yamada:
- Support cross-compiling linux-headers Debian package and kernel-devel
RPM package
- Add support for the linux-debug Pacman package
- Improve module rebuilding speed by factoring out the common code to
scripts/module-common.c
- Separate device tree build rules into scripts/Makefile.dtbs
- Add a new script to generate modules.builtin.ranges, which is useful
for tracing tools to find symbols in built-in modules
- Refactor Kconfig and misc tools
- Update Kbuild and Kconfig documentation
* tag 'kbuild-v6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (51 commits)
kbuild: doc: replace "gcc" in external module description
kbuild: doc: describe the -C option precisely for external module builds
kbuild: doc: remove the description about shipped files
kbuild: doc: drop section numbering, use references in modules.rst
kbuild: doc: throw out the local table of contents in modules.rst
kbuild: doc: remove outdated description of the limitation on -I usage
kbuild: doc: remove description about grepping CONFIG options
kbuild: doc: update the description about Kbuild/Makefile split
kbuild: remove unnecessary export of RUST_LIB_SRC
kbuild: remove append operation on cmd_ld_ko_o
kconfig: cache expression values
kconfig: use hash table to reuse expressions
kconfig: refactor expr_eliminate_dups()
kconfig: add comments to expression transformations
kconfig: change some expr_*() functions to bool
scripts: move hash function from scripts/kconfig/ to scripts/include/
kallsyms: change overflow variable to bool type
kallsyms: squash output_address()
kbuild: add install target for modules.builtin.ranges
scripts: add verifier script for builtin module range data
...
In order to create the file at build time, modules.builtin.ranges, that
contains the range of addresses for all built-in modules, there needs to
be a way to identify what code is compiled into modules.
To identify what code is compiled into modules during a kernel build,
one can look for the presence of the -DKBUILD_MODFILE and -DKBUILD_MODNAME
options in the compile command lines. A simple grep in .*.cmd files for
those options is sufficient for this.
Unfortunately, these options are only passed when compiling C source files.
Various modules also include objects built from assembler source, and these
options are not passed in that case.
Adding $(modfile_flags) to modkern_aflags (similar to modkern_cflags), and
adding $(modname_flags) to a_flags (similar to c_flags) makes it possible
to identify which objects are compiled into modules for both C and
assembler source files. While KBUILD_MODFILE is sufficient to generate
the modules ranges data, KBUILD_MODNAME is passed as well for consistency
with the C source code case.
Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Tested-by: Sam James <sam@gentoo.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Tested-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
scripts/Makefile.lib is included not only from scripts/Makefile.build
but also from scripts/Makefile.{modfinal,package,vmlinux,vmlinux_o},
where DT build rules are not required.
Split the DT build rules out to scripts/Makefile.dtbs, and include it
only when necessary.
While I was here, I added $(DT_TMP_SCHEMA) as a prerequisite of
$(multi-dtb-y).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
When resolving a merge conflict, Linus noticed the fdtoverlay command
duplication introduced by commit 49636c5680 ("kbuild: verify dtoverlay
files against schema"). He suggested a clean-up.
I eliminated the duplication and refactored the code a little further.
No functional changes are intended, except for the short logs.
The log will look as follows:
$ make ARCH=arm64 defconfig dtbs_check
[ snip ]
DTC [C] arch/arm64/boot/dts/freescale/imx93-tqma9352-mba93xxca.dtb
DTC [C] arch/arm64/boot/dts/freescale/imx93-tqma9352-mba93xxla.dtb
DTC [C] arch/arm64/boot/dts/freescale/imx93-var-som-symphony.dtb
DTC [C] arch/arm64/boot/dts/freescale/imx95-19x19-evk.dtb
DTC arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-imx219.dtbo
OVL [C] arch/arm64/boot/dts/freescale/imx8mm-venice-gw72xx-0x-imx219.dtb
The tag [C] indicates that the schema check is executed.
Link: https://lore.kernel.org/lkml/CAHk-=wiF3yeWehcvqY-4X7WNb8n4yw_5t0H1CpEpKi7JMjaMfw@mail.gmail.com/#t
Requested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Pull Kbuild updates from Masahiro Yamada:
- Remove tristate choice support from Kconfig
- Stop using the PROVIDE() directive in the linker script
- Reduce the number of links for the combination of CONFIG_KALLSYMS and
CONFIG_DEBUG_INFO_BTF
- Enable the warning for symbol reference to .exit.* sections by
default
- Fix warnings in RPM package builds
- Improve scripts/make_fit.py to generate a FIT image with separate
base DTB and overlays
- Improve choice value calculation in Kconfig
- Fix conditional prompt behavior in choice in Kconfig
- Remove support for the uncommon EMAIL environment variable in Debian
package builds
- Remove support for the uncommon "name <email>" form for the DEBEMAIL
environment variable
- Raise the minimum supported GNU Make version to 4.0
- Remove stale code for the absolute kallsyms
- Move header files commonly used for host programs to scripts/include/
- Introduce the pacman-pkg target to generate a pacman package used in
Arch Linux
- Clean up Kconfig
* tag 'kbuild-v6.11' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (65 commits)
kbuild: doc: gcc to CC change
kallsyms: change sym_entry::percpu_absolute to bool type
kallsyms: unify seq and start_pos fields of struct sym_entry
kallsyms: add more original symbol type/name in comment lines
kallsyms: use \t instead of a tab in printf()
kallsyms: avoid repeated calculation of array size for markers
kbuild: add script and target to generate pacman package
modpost: use generic macros for hash table implementation
kbuild: move some helper headers from scripts/kconfig/ to scripts/include/
Makefile: add comment to discourage tools/* addition for kernel builds
kbuild: clean up scripts/remove-stale-files
kconfig: recursive checks drop file/lineno
kbuild: rpm-pkg: introduce a simple changelog section for kernel.spec
kallsyms: get rid of code for absolute kallsyms
kbuild: Create INSTALL_PATH directory if it does not exist
kbuild: Abort make on install failures
kconfig: remove 'e1' and 'e2' macros from expression deduplication
kconfig: remove SYMBOL_CHOICEVAL flag
kconfig: add const qualifiers to several function arguments
kconfig: call expr_eliminate_yn() at least once in expr_eliminate_dups()
...
As commit afa974b771 ("kbuild: add real-prereqs shorthand for
$(filter-out FORCE,$^)") explained, $(real-prereqs) is not just a list
of objects when linking a multi-object module. If a single-object module
is turned into a multi-object module, $^ (and therefore $(real-prereqs)
as well) contains header files recorded in the *.cmd file. Such headers
must be filtered out.
Now that a DTB can be built either from a single source or multiple
source files, the same issue can occur.
Consider the following scenario:
First, foo.dtb is implemented as a single-blob device tree.
The code looks something like this:
[Sample Code 1]
Makefile:
dtb-y += foo.dtb
foo.dts:
#include <dt-bindings/gpio/gpio.h>
/dts-v1/;
/ { };
When it is compiled, .foo.dtb.cmd records that foo.dtb depends on
scripts/dtc/include-prefixes/dt-bindings/gpio/gpio.h.
Later, foo.dtb is split into a base and an overlay. The code looks
something like this:
[Sample Code 2]
Makefile:
dtb-y += foo.dtb
foo-dtbs := foo-base.dtb foo-addon.dtbo
foo-base.dts:
#include <dt-bindings/gpio/gpio.h>
/dts-v1/;
/ { };
foo-addon.dtso:
/dts-v1/;
/plugin/;
/ { };
If you rebuild foo.dtb without 'make clean', you will get this error:
Overlay 'scripts/dtc/include-prefixes/dt-bindings/gpio/gpio.h' is incomplete
$(real-prereqs) contains not only foo-base.dtb and foo-addon.dtbo but
also scripts/dtc/include-prefixes/dt-bindings/gpio/gpio.h, which is
passed to scripts/dtc/fdtoverlay.
Fixes: 15d16d6dad ("kbuild: Add generic rule to apply fdtoverlay")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The kernel tree builds some "composite" DTBs, where the final DTB is the
result of applying one or more DTB overlays on top of a base DTB with
fdtoverlay.
The FIT image specification already supports configurations having one
base DTB and overlays applied on top. It is then up to the bootloader to
apply said overlays and either use or pass on the final result. This
allows the FIT image builder to reuse the same FDT images for multiple
configurations, if such cases exist.
The decomposition function depends on the kernel build system, reading
back the .cmd files for the to-be-packaged DTB files to check for the
fdtoverlay command being called. This will not work outside the kernel
tree. The function is off by default to keep compatibility with possible
existing users.
To facilitate the decomposition and keep the code clean, the model and
compatitble string extraction have been moved out of the output_dtb
function. The FDT image description is replaced with the base file name
of the included image.
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Pull Kbuild updates from Masahiro Yamada:
- Avoid 'constexpr', which is a keyword in C23
- Allow 'dtbs_check' and 'dt_compatible_check' run independently of
'dt_binding_check'
- Fix weak references to avoid GOT entries in position-independent code
generation
- Convert the last use of 'optional' property in arch/sh/Kconfig
- Remove support for the 'optional' property in Kconfig
- Remove support for Clang's ThinLTO caching, which does not work with
the .incbin directive
- Change the semantics of $(src) so it always points to the source
directory, which fixes Makefile inconsistencies between upstream and
downstream
- Fix 'make tar-pkg' for RISC-V to produce a consistent package
- Provide reasonable default coverage for objtool, sanitizers, and
profilers
- Remove redundant OBJECT_FILES_NON_STANDARD, KASAN_SANITIZE, etc.
- Remove the last use of tristate choice in drivers/rapidio/Kconfig
- Various cleanups and fixes in Kconfig
* tag 'kbuild-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (46 commits)
kconfig: use sym_get_choice_menu() in sym_check_prop()
rapidio: remove choice for enumeration
kconfig: lxdialog: remove initialization with A_NORMAL
kconfig: m/nconf: merge two item_add_str() calls
kconfig: m/nconf: remove dead code to display value of bool choice
kconfig: m/nconf: remove dead code to display children of choice members
kconfig: gconf: show checkbox for choice correctly
kbuild: use GCOV_PROFILE and KCSAN_SANITIZE in scripts/Makefile.modfinal
Makefile: remove redundant tool coverage variables
kbuild: provide reasonable defaults for tool coverage
modules: Drop the .export_symbol section from the final modules
kconfig: use menu_list_for_each_sym() in sym_check_choice_deps()
kconfig: use sym_get_choice_menu() in conf_write_defconfig()
kconfig: add sym_get_choice_menu() helper
kconfig: turn defaults and additional prompt for choice members into error
kconfig: turn missing prompt for choice members into error
kconfig: turn conf_choice() into void function
kconfig: use linked list in sym_set_changed()
kconfig: gconf: use MENU_CHANGED instead of SYMBOL_CHANGED
kconfig: gconf: remove debug code
...
The objtool, sanitizers (KASAN, UBSAN, etc.), and profilers (GCOV, etc.)
are intended only for kernel space objects.
For instance, the following are not kernel objects, and therefore should
opt out of coverage:
- vDSO
- purgatory
- bootloader (arch/*/boot/)
However, to exclude these from coverage, you need to explicitly set
OBJECT_FILES_NON_STNDARD=y, KASAN_SANITIZE=n, etc.
Kbuild can achieve this without relying on such variables because
objects not directly linked to vmlinux or modules are considered
"non-standard objects".
Detecting standard objects is straightforward:
- objects added to obj-y or lib-y are linked to vmlinux
- objects added to obj-m are linked to modules
There are some exceptional Makefiles (e.g., arch/s390/boot/Makefile,
arch/xtensa/boot/lib/Makefile) that use obj-y or lib-y for non-kernel
space objects, but they can be fixed later if necessary.
Going forward, objects that are not listed in obj-y, lib-y, or obj-m
will opt out of objtool, sanitizers, and profilers by default.
You can still override the Kbuild decision by explicitly specifying
OBJECT_FILES_NON_STANDARD, KASAN_SANITIZE, etc. but most of such Make
variables can be removed.
The next commit will clean up redundant variables.
Note:
This commit changes the coverage for some objects:
- exclude .vmlinux.export.o from UBSAN, KCOV
- exclude arch/csky/kernel/vdso/vgettimeofday.o from UBSAN
- exclude arch/parisc/kernel/vdso32/vdso32.so from UBSAN
- exclude arch/parisc/kernel/vdso64/vdso64.so from UBSAN
- exclude arch/x86/um/vdso/um_vdso.o from UBSAN
- exclude drivers/misc/lkdtm/rodata.o from UBSAN, KCOV
- exclude init/version-timestamp.o from UBSAN, KCOV
- exclude lib/test_fortify/*.o from all santizers and profilers
I believe these are positive effects.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Roberto Sassu <roberto.sassu@huawei.com>
Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:
src := $(obj)
When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.
This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.
To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.
Going forward, the variables used in Makefiles will have the following
meanings:
$(obj) - directory in the object tree
$(src) - directory in the source tree (changed by this commit)
$(objtree) - the top of the kernel object tree
$(srctree) - the top of the kernel source tree
Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:
src := $(obj)
Before changing the semantics of $(src) in the next commit, this commit
replaces $(obj)/ with $(src)/ in pattern rules where the prerequisite
might be a generated file.
C, assembly, Rust, and DTS files are sometimes generated by tools, so
they could be either generated files or real sources. The $(obj)/ prefix
works for both cases with the help of VPATH.
As mentioned above, $(obj) and $(src) are the same at this point, hence
this commit has no functional change.
I did not modify scripts/Makefile.userprogs because there is no use
case where userspace C files are generated.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
scripts/Makefile.lib is included not only from scripts/Makefile.build
but also from scripts/Makefile.{vmlinux,modfinal} for building generated
C files.
In scripts/Makefile.{vmlinux,modfinal}, $(obj) and $(src) are empty.
Therefore, the header include paths:
-I $(srctree)/$(src) -I $(objtree)/$(obj)
... become meaningless code:
-I $(srctree)/ -I $(objtree)/
Add these paths only when 'obj' and 'src' are defined.
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/oe-kbuild-all/202404170634.BlqTaYA0-lkp@intel.com/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <n.schier@avm.de>
