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linux/rust/Makefile
Gary Guo 3a2486cc1d kbuild: rust: provide an option to inline C helpers into Rust 
A new experimental Kconfig option, `RUST_INLINE_HELPERS` is added to
allow C helpers (which were created to allow Rust to call into
inline/macro C functions without having to re-implement the logic in
Rust) to be inlined into Rust crates without performing global LTO.

If the option is enabled, the following is performed:
* For helpers, instead of compiling them to an object file to be linked
  into vmlinux, they're compiled to LLVM IR bitcode. Two versions are
  generated: one for built-in code (`helpers.bc`) and one for modules
  (`helpers_module.bc`, with -DMODULE defined). This ensures that C
  macros/inlines that behave differently for modules (e.g. static calls)
  function correctly when inlined.
* When a Rust crate or object is compiled, instead of generating an
  object file, LLVM bitcode is generated.
* llvm-link is invoked with --internalize to combine the helper bitcode
  with the crate bitcode. This step is similar to LTO, but this is much
  faster since it only needs to inline the helpers.
* clang is invoked to turn the combined bitcode into a final object file.
* Since clang may produce LLVM bitcode when LTO is enabled, and objtool
  requires ELF input, $(cmd_ld_single) is invoked to ensure the object
  is converted to ELF before objtool runs.

The --internalize flag tells llvm-link to treat all symbols in
helpers.bc using `internal` linkage [1]. This matches the behavior of
`clang` on `static inline` functions, and avoids exporting the symbol
from the object file.

To ensure that RUST_INLINE_HELPERS is not incompatible with BTF, we pass
the -g0 flag when building helpers. See commit 5daa0c35a1 ("rust:
Disallow BTF generation with Rust + LTO") for details.

We have an intended triple mismatch of `aarch64-unknown-none` vs
`aarch64-unknown-linux-gnu`, so we pass --suppress-warnings to llvm-link
to suppress it.

I considered adding some sort of check that KBUILD_MODNAME is not
present in helpers_module.bc, but this is actually not so easy to carry
out because .bc files store strings in a weird binary format, so you
cannot just grep it for a string to check whether it ended up using
KBUILD_MODNAME anywhere.

[ Andreas writes:

    For the rnull driver, enabling helper inlining with this patch
    gives an average speedup of 2% over the set of 120 workloads that
    we publish on [2].

    Link: https://rust-for-linux.com/null-block-driver [2]

  This series also uncovered a pre-existing UB instance thanks to an
  `objtool` warning which I noticed while testing the series (details
  in the mailing list).

      - Miguel ]

Link: https://github.com/llvm/llvm-project/pull/170397 [1]
Co-developed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Co-developed-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://patch.msgid.link/20260203-inline-helpers-v2-3-beb8547a03c9@google.com
[ Some changes, apart from the rebase:

  - Added "(EXPERIMENTAL)" to Kconfig as the commit mentions.

  - Added `depends on ARM64 || X86_64` and `!UML` for now, since this is
    experimental, other architectures may require other changes (e.g.
    the issues I mentioned in the mailing list for ARM and UML) and they
    are not really tested so far. So let arch maintainers pick this up
    if they think it is worth it.

  - Gated the `cmd_ld_single` step also into the new mode, which also
    means that any possible future `objcopy` step is done after the
    translation, as expected.

  - Added `.gitignore` for `.bc` with exception for existing script.

  - Added `part-of-*` for helpers bitcode files as discussed, and
    dropped `$(if $(filter %_module.bc,$@),-DMODULE)` since `-DMODULE`
    is already there (would be duplicated otherwise).

  - Moved `LLVM_LINK` to keep binutils list alphabetized.

  - Fixed typo in title.

  - Dropped second `cmd_ld_single` commit message paragraph.

      - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
2026-03-30 02:03:52 +02:00

739 lines
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Makefile
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# SPDX-License-Identifier: GPL-2.0
# Where to place rustdoc generated documentation
rustdoc_output := $(objtree)/Documentation/output/rust/rustdoc
obj-$(CONFIG_RUST) += core.o compiler_builtins.o ffi.o
always-$(CONFIG_RUST) += exports_core_generated.h
ifdef CONFIG_RUST_INLINE_HELPERS
always-$(CONFIG_RUST) += helpers/helpers.bc helpers/helpers_module.bc
else
obj-$(CONFIG_RUST) += helpers/helpers.o
always-$(CONFIG_RUST) += exports_helpers_generated.h
endif
# Missing prototypes are expected in the helpers since these are exported
# for Rust only, thus there is no header nor prototypes.
CFLAGS_REMOVE_helpers/helpers.o = -Wmissing-prototypes -Wmissing-declarations
always-$(CONFIG_RUST) += bindings/bindings_generated.rs bindings/bindings_helpers_generated.rs
obj-$(CONFIG_RUST) += bindings.o pin_init.o kernel.o
always-$(CONFIG_RUST) += exports_bindings_generated.h exports_kernel_generated.h
always-$(CONFIG_RUST) += uapi/uapi_generated.rs
obj-$(CONFIG_RUST) += uapi.o
ifdef CONFIG_RUST_BUILD_ASSERT_ALLOW
obj-$(CONFIG_RUST) += build_error.o
else
always-$(CONFIG_RUST) += build_error.o
endif
obj-$(CONFIG_RUST) += exports.o
always-$(CONFIG_RUST) += libproc_macro2.rlib libquote.rlib libsyn.rlib
always-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated.rs
always-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated_kunit.c
obj-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated.o
obj-$(CONFIG_RUST_KERNEL_DOCTESTS) += doctests_kernel_generated_kunit.o
always-$(subst y,$(CONFIG_RUST),$(CONFIG_JUMP_LABEL)) += kernel/generated_arch_static_branch_asm.rs
ifndef CONFIG_UML
always-$(subst y,$(CONFIG_RUST),$(CONFIG_BUG)) += kernel/generated_arch_warn_asm.rs kernel/generated_arch_reachable_asm.rs
endif
# Avoids running `$(RUSTC)` when it may not be available.
ifdef CONFIG_RUST
libmacros_name := $(shell MAKEFLAGS= $(RUSTC) --print file-names --crate-name macros --crate-type proc-macro - </dev/null)
libmacros_extension := $(patsubst libmacros.%,%,$(libmacros_name))
libpin_init_internal_name := $(shell MAKEFLAGS= $(RUSTC) --print file-names --crate-name pin_init_internal --crate-type proc-macro - </dev/null)
libpin_init_internal_extension := $(patsubst libpin_init_internal.%,%,$(libpin_init_internal_name))
always-$(CONFIG_RUST) += $(libmacros_name) $(libpin_init_internal_name)
# `$(rust_flags)` is passed in case the user added `--sysroot`.
rustc_sysroot := $(shell MAKEFLAGS= $(RUSTC) $(rust_flags) --print sysroot)
rustc_host_target := $(shell $(RUSTC) --version --verbose | grep -F 'host: ' | cut -d' ' -f2)
RUST_LIB_SRC ?= $(rustc_sysroot)/lib/rustlib/src/rust/library
ifneq ($(quiet),)
rust_test_quiet=-q
rustdoc_test_quiet=--test-args -q
rustdoc_test_kernel_quiet=>/dev/null
endif
cfgs-to-flags = $(patsubst %,--cfg='%',$1)
core-cfgs := \
no_fp_fmt_parse
core-edition := $(if $(call rustc-min-version,108700),2024,2021)
core-skip_flags := \
--edition=2021 \
-Wunreachable_pub \
-Wrustdoc::unescaped_backticks
core-flags := \
--edition=$(core-edition) \
$(call cfgs-to-flags,$(core-cfgs))
proc_macro2-cfgs := \
feature="proc-macro" \
wrap_proc_macro \
$(if $(call rustc-min-version,108800),proc_macro_span_file proc_macro_span_location)
# Stable since Rust 1.79.0: `feature(proc_macro_byte_character,proc_macro_c_str_literals)`.
proc_macro2-flags := \
--cap-lints=allow \
-Zcrate-attr='feature(proc_macro_byte_character,proc_macro_c_str_literals)' \
$(call cfgs-to-flags,$(proc_macro2-cfgs))
quote-cfgs := \
feature="proc-macro"
quote-skip_flags := \
--edition=2021
quote-flags := \
--edition=2018 \
--cap-lints=allow \
--extern proc_macro2 \
$(call cfgs-to-flags,$(quote-cfgs))
# `extra-traits`, `fold` and `visit` may be enabled if needed.
syn-cfgs := \
feature="clone-impls" \
feature="derive" \
feature="full" \
feature="parsing" \
feature="printing" \
feature="proc-macro" \
feature="visit-mut"
syn-flags := \
--cap-lints=allow \
--extern proc_macro2 \
--extern quote \
$(call cfgs-to-flags,$(syn-cfgs))
pin_init_internal-cfgs := \
kernel
pin_init_internal-flags := \
--extern proc_macro2 \
--extern quote \
--extern syn \
$(call cfgs-to-flags,$(pin_init_internal-cfgs))
pin_init-cfgs := \
kernel
pin_init-flags := \
--extern pin_init_internal \
--extern macros \
$(call cfgs-to-flags,$(pin_init-cfgs))
# `rustdoc` did not save the target modifiers, thus workaround for
# the time being (https://github.com/rust-lang/rust/issues/144521).
rustdoc_modifiers_workaround := $(if $(call rustc-min-version,108800),-Cunsafe-allow-abi-mismatch=fixed-x18)
# Similarly, for doctests (https://github.com/rust-lang/rust/issues/146465).
doctests_modifiers_workaround := $(rustdoc_modifiers_workaround)$(if $(call rustc-min-version,109100),$(comma)sanitizer)
# `rustc` recognizes `--remap-path-prefix` since 1.26.0, but `rustdoc` only
# since Rust 1.81.0. Moreover, `rustdoc` ICEs on out-of-tree builds since Rust
# 1.82.0 (https://github.com/rust-lang/rust/issues/138520). Thus workaround both
# issues skipping the flag. The former also applies to `RUSTDOC TK`.
quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
cmd_rustdoc = \
OBJTREE=$(abspath $(objtree)) \
$(RUSTDOC) $(filter-out $(skip_flags) --remap-path-prefix=%,$(if $(rustdoc_host),$(rust_common_flags),$(rust_flags))) \
$(rustc_target_flags) -L$(objtree)/$(obj) \
-Zunstable-options --generate-link-to-definition \
--output $(rustdoc_output) \
--crate-name $(subst rustdoc-,,$@) \
$(rustdoc_modifiers_workaround) \
$(if $(rustdoc_host),,--sysroot=/dev/null) \
@$(objtree)/include/generated/rustc_cfg $<
# The `html_logo_url` and `html_favicon_url` forms of the `doc` attribute
# can be used to specify a custom logo. However:
# - The given value is used as-is, thus it cannot be relative or a local file
# (unlike the non-custom case) since the generated docs have subfolders.
# - It requires adding it to every crate.
# - It requires changing `core` which comes from the sysroot.
#
# Using `-Zcrate-attr` would solve the last two points, but not the first.
# The https://github.com/rust-lang/rfcs/pull/3226 RFC suggests two new
# command-like flags to solve the issue. Meanwhile, we use the non-custom case
# and then retouch the generated files.
rustdoc: rustdoc-core rustdoc-macros rustdoc-compiler_builtins \
rustdoc-kernel rustdoc-pin_init
$(Q)grep -Ehro '<a href="srctree/([^"]+)"' $(rustdoc_output) | \
cut -d'"' -f2 | cut -d/ -f2- | while read f; do \
if [ ! -e "$(srctree)/$$f" ]; then \
echo "warning: srctree/ link to $$f does not exist"; \
fi \
done
$(Q)cp $(srctree)/Documentation/images/logo.svg $(rustdoc_output)/static.files/
$(Q)cp $(srctree)/Documentation/images/COPYING-logo $(rustdoc_output)/static.files/
$(Q)find $(rustdoc_output) -name '*.html' -type f -print0 | xargs -0 sed -Ei \
-e 's:rust-logo-[0-9a-f]+\.svg:logo.svg:g' \
-e 's:favicon-[0-9a-f]+\.svg:logo.svg:g' \
-e 's:<link rel="alternate icon" type="image/png" href="[/.]+/static\.files/favicon-(16x16|32x32)-[0-9a-f]+\.png">::g' \
-e 's:<a href="srctree/([^"]+)">:<a href="$(realpath $(srctree))/\1">:g'
$(Q)for f in $(rustdoc_output)/static.files/rustdoc-*.css; do \
echo ".logo-container > img { object-fit: contain; }" >> $$f; done
rustdoc-proc_macro2: private rustdoc_host = yes
rustdoc-proc_macro2: private rustc_target_flags = $(proc_macro2-flags)
rustdoc-proc_macro2: $(src)/proc-macro2/lib.rs rustdoc-clean FORCE
+$(call if_changed,rustdoc)
rustdoc-quote: private rustdoc_host = yes
rustdoc-quote: private rustc_target_flags = $(quote-flags)
rustdoc-quote: private skip_flags = $(quote-skip_flags)
rustdoc-quote: $(src)/quote/lib.rs rustdoc-clean rustdoc-proc_macro2 FORCE
+$(call if_changed,rustdoc)
rustdoc-syn: private rustdoc_host = yes
rustdoc-syn: private rustc_target_flags = $(syn-flags)
rustdoc-syn: $(src)/syn/lib.rs rustdoc-clean rustdoc-quote FORCE
+$(call if_changed,rustdoc)
rustdoc-macros: private rustdoc_host = yes
rustdoc-macros: private rustc_target_flags = --crate-type proc-macro \
--extern proc_macro --extern proc_macro2 --extern quote --extern syn
rustdoc-macros: $(src)/macros/lib.rs rustdoc-clean rustdoc-proc_macro2 \
rustdoc-quote rustdoc-syn FORCE
+$(call if_changed,rustdoc)
# Starting with Rust 1.82.0, skipping `-Wrustdoc::unescaped_backticks` should
# not be needed -- see https://github.com/rust-lang/rust/pull/128307.
rustdoc-core: private skip_flags = $(core-skip_flags)
rustdoc-core: private rustc_target_flags = $(core-flags)
rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs rustdoc-clean FORCE
+$(call if_changed,rustdoc)
# Even if `rustdoc` targets are not kernel objects, they should still be
# treated as such so that we pass the same flags. Otherwise, for instance,
# `rustdoc` will complain about missing sanitizer flags causing an ABI mismatch.
rustdoc-compiler_builtins: private is-kernel-object := y
rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE
+$(call if_changed,rustdoc)
rustdoc-ffi: private is-kernel-object := y
rustdoc-ffi: $(src)/ffi.rs rustdoc-core FORCE
+$(call if_changed,rustdoc)
rustdoc-pin_init_internal: private rustdoc_host = yes
rustdoc-pin_init_internal: private rustc_target_flags = $(pin_init_internal-flags) \
--extern proc_macro --crate-type proc-macro
rustdoc-pin_init_internal: $(src)/pin-init/internal/src/lib.rs \
rustdoc-clean rustdoc-proc_macro2 rustdoc-quote rustdoc-syn FORCE
+$(call if_changed,rustdoc)
rustdoc-pin_init: private rustdoc_host = yes
rustdoc-pin_init: private rustc_target_flags = $(pin_init-flags) \
--extern alloc --cfg feature=\"alloc\"
rustdoc-pin_init: $(src)/pin-init/src/lib.rs rustdoc-pin_init_internal \
rustdoc-macros FORCE
+$(call if_changed,rustdoc)
rustdoc-kernel: private is-kernel-object := y
rustdoc-kernel: private rustc_target_flags = --extern ffi --extern pin_init \
--extern build_error --extern macros \
--extern bindings --extern uapi
rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-ffi rustdoc-macros \
rustdoc-pin_init rustdoc-compiler_builtins $(obj)/$(libmacros_name) \
$(obj)/bindings.o FORCE
+$(call if_changed,rustdoc)
rustdoc-clean: FORCE
$(Q)rm -rf $(rustdoc_output)
quiet_cmd_rustc_test_library = $(RUSTC_OR_CLIPPY_QUIET) TL $<
cmd_rustc_test_library = \
OBJTREE=$(abspath $(objtree)) \
$(RUSTC_OR_CLIPPY) $(filter-out $(skip_flags),$(rust_common_flags) $(rustc_target_flags)) \
@$(objtree)/include/generated/rustc_cfg \
--crate-type $(if $(rustc_test_library_proc),proc-macro,rlib) \
--out-dir $(objtree)/$(obj)/test --cfg testlib \
-L$(objtree)/$(obj)/test \
--crate-name $(subst rusttest-,,$(subst rusttestlib-,,$@)) $<
rusttestlib-build_error: $(src)/build_error.rs FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-ffi: $(src)/ffi.rs FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-proc_macro2: private rustc_target_flags = $(proc_macro2-flags)
rusttestlib-proc_macro2: $(src)/proc-macro2/lib.rs FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-quote: private skip_flags = $(quote-skip_flags)
rusttestlib-quote: private rustc_target_flags = $(quote-flags)
rusttestlib-quote: $(src)/quote/lib.rs rusttestlib-proc_macro2 FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-syn: private rustc_target_flags = $(syn-flags)
rusttestlib-syn: $(src)/syn/lib.rs rusttestlib-quote FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-macros: private rustc_target_flags = --extern proc_macro \
--extern proc_macro2 --extern quote --extern syn
rusttestlib-macros: private rustc_test_library_proc = yes
rusttestlib-macros: $(src)/macros/lib.rs \
rusttestlib-proc_macro2 rusttestlib-quote rusttestlib-syn FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-pin_init_internal: private rustc_target_flags = $(pin_init_internal-flags) \
--extern proc_macro
rusttestlib-pin_init_internal: private rustc_test_library_proc = yes
rusttestlib-pin_init_internal: $(src)/pin-init/internal/src/lib.rs \
rusttestlib-proc_macro2 rusttestlib-quote rusttestlib-syn FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-pin_init: private rustc_target_flags = $(pin_init-flags)
rusttestlib-pin_init: $(src)/pin-init/src/lib.rs rusttestlib-macros \
rusttestlib-pin_init_internal $(obj)/$(libpin_init_internal_name) FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-kernel: private rustc_target_flags = --extern ffi \
--extern build_error --extern macros --extern pin_init \
--extern bindings --extern uapi
rusttestlib-kernel: $(src)/kernel/lib.rs rusttestlib-bindings rusttestlib-uapi \
rusttestlib-build_error rusttestlib-pin_init $(obj)/$(libmacros_name) \
$(obj)/bindings.o FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-bindings: private rustc_target_flags = --extern ffi --extern pin_init
rusttestlib-bindings: $(src)/bindings/lib.rs rusttestlib-ffi rusttestlib-pin_init FORCE
+$(call if_changed,rustc_test_library)
rusttestlib-uapi: private rustc_target_flags = --extern ffi --extern pin_init
rusttestlib-uapi: $(src)/uapi/lib.rs rusttestlib-ffi rusttestlib-pin_init FORCE
+$(call if_changed,rustc_test_library)
quiet_cmd_rustdoc_test = RUSTDOC T $<
cmd_rustdoc_test = \
RUST_MODFILE=test.rs \
OBJTREE=$(abspath $(objtree)) \
$(RUSTDOC) --test $(rust_common_flags) \
-Zcrate-attr='feature(used_with_arg)' \
@$(objtree)/include/generated/rustc_cfg \
$(rustc_target_flags) $(rustdoc_test_target_flags) \
$(rustdoc_test_quiet) \
-L$(objtree)/$(obj)/test --output $(rustdoc_output) \
--crate-name $(subst rusttest-,,$@) $<
quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $<
cmd_rustdoc_test_kernel = \
rm -rf $(objtree)/$(obj)/test/doctests/kernel; \
mkdir -p $(objtree)/$(obj)/test/doctests/kernel; \
OBJTREE=$(abspath $(objtree)) \
$(RUSTDOC) --test $(filter-out --remap-path-prefix=%,$(rust_flags)) \
-L$(objtree)/$(obj) --extern ffi --extern pin_init \
--extern kernel --extern build_error --extern macros \
--extern bindings --extern uapi \
--no-run --crate-name kernel -Zunstable-options \
--sysroot=/dev/null \
$(doctests_modifiers_workaround) \
--test-builder $(objtree)/scripts/rustdoc_test_builder \
$< $(rustdoc_test_kernel_quiet); \
$(objtree)/scripts/rustdoc_test_gen
%/doctests_kernel_generated.rs %/doctests_kernel_generated_kunit.c: \
$(src)/kernel/lib.rs $(obj)/kernel.o \
$(objtree)/scripts/rustdoc_test_builder \
$(objtree)/scripts/rustdoc_test_gen FORCE
+$(call if_changed,rustdoc_test_kernel)
# We cannot use `-Zpanic-abort-tests` because some tests are dynamic,
# so for the moment we skip `-Cpanic=abort`.
quiet_cmd_rustc_test = $(RUSTC_OR_CLIPPY_QUIET) T $<
cmd_rustc_test = \
OBJTREE=$(abspath $(objtree)) \
$(RUSTC_OR_CLIPPY) --test $(rust_common_flags) \
@$(objtree)/include/generated/rustc_cfg \
$(rustc_target_flags) --out-dir $(objtree)/$(obj)/test \
-L$(objtree)/$(obj)/test \
--crate-name $(subst rusttest-,,$@) $<; \
$(objtree)/$(obj)/test/$(subst rusttest-,,$@) $(rust_test_quiet) \
$(rustc_test_run_flags)
rusttest: rusttest-macros
rusttest-macros: private rustc_target_flags = --extern proc_macro \
--extern macros --extern kernel --extern pin_init \
--extern proc_macro2 --extern quote --extern syn
rusttest-macros: private rustdoc_test_target_flags = --crate-type proc-macro
rusttest-macros: $(src)/macros/lib.rs \
rusttestlib-macros rusttestlib-kernel rusttestlib-pin_init FORCE
+$(call if_changed,rustc_test)
+$(call if_changed,rustdoc_test)
ifdef CONFIG_CC_IS_CLANG
bindgen_c_flags = $(c_flags)
else
# bindgen relies on libclang to parse C. Ideally, bindgen would support a GCC
# plugin backend and/or the Clang driver would be perfectly compatible with GCC.
#
# For the moment, here we are tweaking the flags on the fly. This is a hack,
# and some kernel configurations may not work (e.g. `GCC_PLUGIN_RANDSTRUCT`
# if we end up using one of those structs).
bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \
-mskip-rax-setup -mgeneral-regs-only -msign-return-address=% \
-mindirect-branch=thunk-extern -mindirect-branch-register \
-mfunction-return=thunk-extern -mrecord-mcount -mabi=lp64 \
-mindirect-branch-cs-prefix -mstack-protector-guard% -mtraceback=no \
-mno-pointers-to-nested-functions -mno-string \
-mno-strict-align -mstrict-align -mdirect-extern-access \
-mexplicit-relocs -mno-check-zero-division \
-fconserve-stack -falign-jumps=% -falign-loops=% \
-femit-struct-debug-baseonly -fno-ipa-cp-clone -fno-ipa-sra \
-fno-partial-inlining -fplugin-arg-arm_ssp_per_task_plugin-% \
-fno-reorder-blocks -fno-allow-store-data-races -fasan-shadow-offset=% \
-fzero-call-used-regs=% -fno-stack-clash-protection \
-fno-inline-functions-called-once -fsanitize=bounds-strict \
-fstrict-flex-arrays=% -fmin-function-alignment=% \
-fzero-init-padding-bits=% -mno-fdpic \
-fdiagnostics-show-context -fdiagnostics-show-context=% \
--param=% --param asan-% -fno-isolate-erroneous-paths-dereference
# Derived from `scripts/Makefile.clang`.
BINDGEN_TARGET_x86 := x86_64-linux-gnu
BINDGEN_TARGET_arm64 := aarch64-linux-gnu
BINDGEN_TARGET_arm := arm-linux-gnueabi
BINDGEN_TARGET_loongarch := loongarch64-linux-gnusf
BINDGEN_TARGET_um := $(BINDGEN_TARGET_$(SUBARCH))
BINDGEN_TARGET := $(BINDGEN_TARGET_$(SRCARCH))
# All warnings are inhibited since GCC builds are very experimental,
# many GCC warnings are not supported by Clang, they may only appear in
# some configurations, with new GCC versions, etc.
bindgen_extra_c_flags = -w --target=$(BINDGEN_TARGET)
# Auto variable zero-initialization requires an additional special option with
# clang that is going to be removed sometime in the future (likely in
# clang-18), so make sure to pass this option only if clang supports it
# (libclang major version < 16).
#
# https://github.com/llvm/llvm-project/issues/44842
# https://github.com/llvm/llvm-project/blob/llvmorg-16.0.0-rc2/clang/docs/ReleaseNotes.rst#deprecated-compiler-flags
ifdef CONFIG_INIT_STACK_ALL_ZERO
libclang_maj_ver=$(shell $(BINDGEN) $(srctree)/scripts/rust_is_available_bindgen_libclang.h 2>&1 | sed -ne 's/.*clang version \([0-9]*\).*/\1/p')
ifeq ($(shell expr $(libclang_maj_ver) \< 16), 1)
bindgen_extra_c_flags += -enable-trivial-auto-var-init-zero-knowing-it-will-be-removed-from-clang
endif
endif
bindgen_c_flags = $(filter-out $(bindgen_skip_c_flags), $(c_flags)) \
$(bindgen_extra_c_flags)
endif
ifdef CONFIG_LTO
bindgen_c_flags_lto = $(filter-out $(CC_FLAGS_LTO), $(bindgen_c_flags))
else
bindgen_c_flags_lto = $(bindgen_c_flags)
endif
# `-fno-builtin` is passed to avoid `bindgen` from using `clang` builtin
# prototypes for functions like `memcpy` -- if this flag is not passed,
# `bindgen`-generated prototypes use `c_ulong` or `c_uint` depending on
# architecture instead of generating `usize`.
bindgen_c_flags_final = $(bindgen_c_flags_lto) -fno-builtin -D__BINDGEN__
# Each `bindgen` release may upgrade the list of Rust target versions. By
# default, the highest stable release in their list is used. Thus we need to set
# a `--rust-target` to avoid future `bindgen` releases emitting code that
# `rustc` may not understand. On top of that, `bindgen` does not support passing
# an unknown Rust target version.
#
# Therefore, the Rust target for `bindgen` can be only as high as the minimum
# Rust version the kernel supports and only as high as the greatest stable Rust
# target supported by the minimum `bindgen` version the kernel supports (that
# is, if we do not test the actual `rustc`/`bindgen` versions running).
#
# Starting with `bindgen` 0.71.0, we will be able to set any future Rust version
# instead, i.e. we will be able to set here our minimum supported Rust version.
quiet_cmd_bindgen = BINDGEN $@
cmd_bindgen = \
$(BINDGEN) $< $(bindgen_target_flags) --rust-target 1.68 \
--use-core --with-derive-default --ctypes-prefix ffi --no-layout-tests \
--no-debug '.*' --enable-function-attribute-detection \
-o $@ -- $(bindgen_c_flags_final) -DMODULE \
$(bindgen_target_cflags) $(bindgen_target_extra)
$(obj)/bindings/bindings_generated.rs: private bindgen_target_flags = \
$(shell grep -Ev '^#|^$$' $(src)/bindgen_parameters)
$(obj)/bindings/bindings_generated.rs: private bindgen_target_extra = ; \
sed -Ei 's/pub const RUST_CONST_HELPER_([a-zA-Z0-9_]*)/pub const \1/g' $@
$(obj)/bindings/bindings_generated.rs: $(src)/bindings/bindings_helper.h \
$(src)/bindgen_parameters FORCE
$(call if_changed_dep,bindgen)
$(obj)/uapi/uapi_generated.rs: private bindgen_target_flags = \
$(shell grep -Ev '^#|^$$' $(src)/bindgen_parameters)
$(obj)/uapi/uapi_generated.rs: $(src)/uapi/uapi_helper.h \
$(src)/bindgen_parameters FORCE
$(call if_changed_dep,bindgen)
# See `CFLAGS_REMOVE_helpers.o` above. In addition, Clang on C does not warn
# with `-Wmissing-declarations` (unlike GCC), so it is not strictly needed here
# given it is `libclang`; but for consistency, future Clang changes and/or
# a potential future GCC backend for `bindgen`, we disable it too.
$(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_flags = \
--blocklist-type '.*' --allowlist-var '' \
--allowlist-function 'rust_helper_.*'
$(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_cflags = \
-I$(objtree)/$(obj) -Wno-missing-prototypes -Wno-missing-declarations
$(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_extra = ; \
sed -Ei 's/pub fn rust_helper_([a-zA-Z0-9_]*)/#[link_name="rust_helper_\1"]\n pub fn \1/g' $@
$(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
$(call if_changed_dep,bindgen)
quiet_cmd_rust_helper = HELPER $@
cmd_rust_helper = \
$(CC) $(filter-out $(CFLAGS_REMOVE_helpers/helpers.o), $(c_flags)) \
-c -g0 $< -emit-llvm -o $@
$(obj)/helpers/helpers.bc: private part-of-builtin := y
$(obj)/helpers/helpers_module.bc: private part-of-module := y
$(obj)/helpers/helpers.bc $(obj)/helpers/helpers_module.bc: $(src)/helpers/helpers.c FORCE
+$(call if_changed_dep,rust_helper)
rust_exports = $(NM) -p --defined-only $(1) | awk '$$2~/(T|R|D|B)/ && $$3!~/__(pfx|cfi|odr_asan)/ { printf $(2),$$3 }'
quiet_cmd_exports = EXPORTS $@
cmd_exports = \
$(call rust_exports,$<,"EXPORT_SYMBOL_RUST_GPL(%s);\n") > $@
$(obj)/exports_core_generated.h: $(obj)/core.o FORCE
$(call if_changed,exports)
# Even though Rust kernel modules should never use the bindings directly,
# symbols from the `bindings` crate and the C helpers need to be exported
# because Rust generics and inlined functions may not get their code generated
# in the crate where they are defined. Other helpers, called from non-inline
# functions, may not be exported, in principle. However, in general, the Rust
# compiler does not guarantee codegen will be performed for a non-inline
# function either. Therefore, we export all symbols from helpers and bindings.
# In the future, this may be revisited to reduce the number of exports after
# the compiler is informed about the places codegen is required.
$(obj)/exports_helpers_generated.h: $(obj)/helpers/helpers.o FORCE
$(call if_changed,exports)
$(obj)/exports_bindings_generated.h: $(obj)/bindings.o FORCE
$(call if_changed,exports)
$(obj)/exports_kernel_generated.h: $(obj)/kernel.o FORCE
$(call if_changed,exports)
quiet_cmd_rustc_procmacrolibrary = $(RUSTC_OR_CLIPPY_QUIET) PL $@
cmd_rustc_procmacrolibrary = \
$(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \
$(filter-out $(skip_flags),$(rust_common_flags) $(rustc_target_flags)) \
--emit=dep-info,link --crate-type rlib -O \
--out-dir $(objtree)/$(obj) -L$(objtree)/$(obj) \
--crate-name $(patsubst lib%.rlib,%,$(notdir $@)) $<; \
mv $(objtree)/$(obj)/$(patsubst lib%.rlib,%,$(notdir $@)).d $(depfile); \
sed -i '/^\#/d' $(depfile)
$(obj)/libproc_macro2.rlib: private skip_clippy = 1
$(obj)/libproc_macro2.rlib: private rustc_target_flags = $(proc_macro2-flags)
$(obj)/libproc_macro2.rlib: $(src)/proc-macro2/lib.rs FORCE
+$(call if_changed_dep,rustc_procmacrolibrary)
$(obj)/libquote.rlib: private skip_clippy = 1
$(obj)/libquote.rlib: private skip_flags = $(quote-skip_flags)
$(obj)/libquote.rlib: private rustc_target_flags = $(quote-flags)
$(obj)/libquote.rlib: $(src)/quote/lib.rs $(obj)/libproc_macro2.rlib FORCE
+$(call if_changed_dep,rustc_procmacrolibrary)
$(obj)/libsyn.rlib: private skip_clippy = 1
$(obj)/libsyn.rlib: private rustc_target_flags = $(syn-flags)
$(obj)/libsyn.rlib: $(src)/syn/lib.rs $(obj)/libquote.rlib FORCE
+$(call if_changed_dep,rustc_procmacrolibrary)
quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
cmd_rustc_procmacro = \
$(RUSTC_OR_CLIPPY) $(rust_common_flags) $(rustc_target_flags) \
-Clinker-flavor=gcc -Clinker=$(HOSTCC) \
-Clink-args='$(call escsq,$(KBUILD_PROCMACROLDFLAGS))' \
--emit=dep-info=$(depfile) --emit=link=$@ --extern proc_macro \
--crate-type proc-macro -L$(objtree)/$(obj) \
--crate-name $(patsubst lib%.$(libmacros_extension),%,$(notdir $@)) \
@$(objtree)/include/generated/rustc_cfg $<
# Procedural macros can only be used with the `rustc` that compiled it.
$(obj)/$(libmacros_name): private rustc_target_flags = \
--extern proc_macro2 --extern quote --extern syn
$(obj)/$(libmacros_name): $(src)/macros/lib.rs $(obj)/libproc_macro2.rlib \
$(obj)/libquote.rlib $(obj)/libsyn.rlib FORCE
+$(call if_changed_dep,rustc_procmacro)
$(obj)/$(libpin_init_internal_name): private rustc_target_flags = $(pin_init_internal-flags)
$(obj)/$(libpin_init_internal_name): $(src)/pin-init/internal/src/lib.rs \
$(obj)/libproc_macro2.rlib $(obj)/libquote.rlib $(obj)/libsyn.rlib FORCE
+$(call if_changed_dep,rustc_procmacro)
# `rustc` requires `-Zunstable-options` to use custom target specifications
# since Rust 1.95.0 (https://github.com/rust-lang/rust/pull/151534).
quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
cmd_rustc_library = \
OBJTREE=$(abspath $(objtree)) \
$(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \
$(filter-out $(skip_flags),$(rust_flags)) $(rustc_target_flags) \
--emit=dep-info=$(depfile) --emit=$(if $(link_helper),llvm-bc=$(patsubst %.o,%.bc,$@),obj=$@) \
--emit=metadata=$(dir $@)$(patsubst %.o,lib%.rmeta,$(notdir $@)) \
--crate-type rlib -L$(objtree)/$(obj) \
--crate-name $(patsubst %.o,%,$(notdir $@)) $< \
--sysroot=/dev/null \
-Zunstable-options \
$(if $(link_helper),;$(LLVM_LINK) --internalize --suppress-warnings $(patsubst %.o,%.bc,$@) \
$(obj)/helpers/helpers$(if $(part-of-module),_module).bc -o $(patsubst %.o,%.m.bc,$@); \
$(CC) $(CLANG_FLAGS) $(KBUILD_CFLAGS) -Wno-override-module -c $(patsubst %.o,%.m.bc,$@) -o $@ \
$(cmd_ld_single)) \
$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@) \
$(cmd_objtool)
rust-analyzer:
$(Q)MAKEFLAGS= $(srctree)/scripts/generate_rust_analyzer.py \
--cfgs='core=$(core-cfgs)' $(core-edition) \
--cfgs='proc_macro2=$(proc_macro2-cfgs)' \
--cfgs='quote=$(quote-cfgs)' \
--cfgs='syn=$(syn-cfgs)' \
$(realpath $(srctree)) $(realpath $(objtree)) \
$(rustc_sysroot) $(RUST_LIB_SRC) $(if $(KBUILD_EXTMOD),$(srcroot)) \
> rust-project.json
redirect-intrinsics = \
__addsf3 __eqsf2 __extendsfdf2 __gesf2 __lesf2 __ltsf2 __mulsf3 __nesf2 __truncdfsf2 __unordsf2 \
__adddf3 __eqdf2 __ledf2 __ltdf2 __muldf3 __unorddf2 \
__muloti4 __multi3 \
__udivmodti4 __udivti3 __umodti3
ifdef CONFIG_ARM
# Add eabi initrinsics for ARM 32-bit
redirect-intrinsics += \
__aeabi_fadd __aeabi_fmul __aeabi_fcmpeq __aeabi_fcmple __aeabi_fcmplt __aeabi_fcmpun \
__aeabi_dadd __aeabi_dmul __aeabi_dcmple __aeabi_dcmplt __aeabi_dcmpun \
__aeabi_uldivmod
endif
ifneq ($(or $(CONFIG_ARM64),$(and $(CONFIG_RISCV),$(CONFIG_64BIT))),)
# These intrinsics are defined for ARM64 and RISCV64
redirect-intrinsics += \
__ashrti3 \
__ashlti3 __lshrti3
endif
ifdef CONFIG_MODVERSIONS
cmd_gendwarfksyms = $(if $(skip_gendwarfksyms),, \
$(call rust_exports,$@,"%s\n") | \
scripts/gendwarfksyms/gendwarfksyms \
$(if $(KBUILD_GENDWARFKSYMS_STABLE), --stable) \
$(if $(KBUILD_SYMTYPES), --symtypes $(@:.o=.symtypes),) \
$@ >> $(dot-target).cmd)
endif
define rule_rustc_library
$(call cmd_and_fixdep,rustc_library)
$(call cmd,gen_objtooldep)
$(call cmd,gendwarfksyms)
endef
define rule_rust_cc_library
$(call if_changed_rule,cc_o_c)
$(call cmd,force_checksrc)
$(call cmd,gendwarfksyms)
endef
# helpers.o uses the same export mechanism as Rust libraries, so ensure symbol
# versions are calculated for the helpers too.
$(obj)/helpers/helpers.o: $(src)/helpers/helpers.c $(recordmcount_source) FORCE
+$(call if_changed_rule,rust_cc_library)
# Disable symbol versioning for exports.o to avoid conflicts with the actual
# symbol versions generated from Rust objects.
$(obj)/exports.o: private skip_gendwarfksyms = 1
$(obj)/core.o: private skip_clippy = 1
$(obj)/core.o: private skip_flags = $(core-skip_flags)
$(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym))
$(obj)/core.o: private rustc_target_flags = $(core-flags)
$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs \
$(wildcard $(objtree)/include/config/RUSTC_VERSION_TEXT) FORCE
+$(call if_changed_rule,rustc_library)
ifneq ($(or $(CONFIG_X86_64),$(CONFIG_X86_32)),)
$(obj)/core.o: scripts/target.json
endif
KCOV_INSTRUMENT_core.o := n
$(obj)/compiler_builtins.o: private skip_gendwarfksyms = 1
$(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
$(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
+$(call if_changed_rule,rustc_library)
$(obj)/pin_init.o: private skip_gendwarfksyms = 1
$(obj)/pin_init.o: private rustc_target_flags = $(pin_init-flags)
$(obj)/pin_init.o: $(src)/pin-init/src/lib.rs $(obj)/compiler_builtins.o \
$(obj)/$(libpin_init_internal_name) $(obj)/$(libmacros_name) FORCE
+$(call if_changed_rule,rustc_library)
# Even if normally `build_error` is not a kernel object, it should still be
# treated as such so that we pass the same flags. Otherwise, for instance,
# `rustc` will complain about missing sanitizer flags causing an ABI mismatch.
$(obj)/build_error.o: private is-kernel-object := y
$(obj)/build_error.o: private skip_gendwarfksyms = 1
$(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
+$(call if_changed_rule,rustc_library)
$(obj)/ffi.o: private skip_gendwarfksyms = 1
$(obj)/ffi.o: $(src)/ffi.rs $(obj)/compiler_builtins.o FORCE
+$(call if_changed_rule,rustc_library)
$(obj)/bindings.o: private rustc_target_flags = --extern ffi --extern pin_init
$(obj)/bindings.o: $(src)/bindings/lib.rs \
$(obj)/ffi.o \
$(obj)/pin_init.o \
$(obj)/bindings/bindings_generated.rs \
$(obj)/bindings/bindings_helpers_generated.rs FORCE
+$(call if_changed_rule,rustc_library)
$(obj)/uapi.o: private rustc_target_flags = --extern ffi --extern pin_init
$(obj)/uapi.o: private skip_gendwarfksyms = 1
$(obj)/uapi.o: $(src)/uapi/lib.rs \
$(obj)/ffi.o \
$(obj)/pin_init.o \
$(obj)/uapi/uapi_generated.rs FORCE
+$(call if_changed_rule,rustc_library)
$(obj)/kernel.o: private rustc_target_flags = --extern ffi --extern pin_init \
--extern build_error --extern macros --extern bindings --extern uapi
$(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/build_error.o $(obj)/pin_init.o \
$(obj)/$(libmacros_name) $(obj)/bindings.o $(obj)/uapi.o FORCE
+$(call if_changed_rule,rustc_library)
ifdef CONFIG_JUMP_LABEL
$(obj)/kernel.o: $(obj)/kernel/generated_arch_static_branch_asm.rs
endif
ifndef CONFIG_UML
ifdef CONFIG_BUG
$(obj)/kernel.o: $(obj)/kernel/generated_arch_warn_asm.rs $(obj)/kernel/generated_arch_reachable_asm.rs
endif
endif
ifdef CONFIG_RUST_INLINE_HELPERS
$(obj)/kernel.o: private link_helper = 1
$(obj)/kernel.o: $(obj)/helpers/helpers.bc
endif
endif # CONFIG_RUST
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