rust/Makefile - linux - Git at Google

 # SPDX-License-Identifier: GPL-2.0

 always-$(CONFIG_RUST) += target.json
 no-clean-files += target.json

 obj-$(CONFIG_RUST) += core.o compiler_builtins.o
 always-$(CONFIG_RUST) += exports_core_generated.h

 # Missing prototypes are expected in the helpers since these are exported
 # for Rust only, thus there is no header nor prototypes.
 obj-$(CONFIG_RUST) += helpers.o
 CFLAGS_REMOVE_helpers.o = -Wmissing-prototypes -Wmissing-declarations

 always-$(CONFIG_RUST) += libmacros.so
 no-clean-files += libmacros.so

 always-$(CONFIG_RUST) += bindings/bindings_generated.rs bindings/bindings_helpers_generated.rs
 obj-$(CONFIG_RUST) += alloc.o bindings.o kernel.o
 always-$(CONFIG_RUST) += exports_alloc_generated.h exports_bindings_generated.h \
     exports_kernel_generated.h

 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

 # Avoids running `$(RUSTC)` for the sysroot when it may not be available.
 ifdef CONFIG_RUST

 # `$(rust_flags)` is passed in case the user added `--sysroot`.
 rustc_sysroot := $(shell $(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

 ifeq ($(quiet),silent_)
 cargo_quiet=-q
 rust_test_quiet=-q
 rustdoc_test_quiet=--test-args -q
 else ifeq ($(quiet),quiet_)
 rust_test_quiet=-q
 rustdoc_test_quiet=--test-args -q
 else
 cargo_quiet=--verbose
 endif

 core-cfgs = \
     --cfg no_fp_fmt_parse

 alloc-cfgs = \
     --cfg no_fmt \
     --cfg no_global_oom_handling \
     --cfg no_macros \
     --cfg no_rc \
     --cfg no_str \
     --cfg no_string \
     --cfg no_sync \
     --cfg no_thin

 quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
       cmd_rustdoc = \
 	OBJTREE=$(abspath $(objtree)) \
 	$(RUSTDOC) $(if $(rustdoc_host),$(rust_common_flags),$(rust_flags)) \
 		$(rustc_target_flags) -L$(objtree)/$(obj) \
 		--output $(objtree)/$(obj)/doc \
 		--crate-name $(subst rustdoc-,,$@) \
 		@$(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-alloc rustdoc-kernel
 	$(Q)cp $(srctree)/Documentation/images/logo.svg $(objtree)/$(obj)/doc
 	$(Q)cp $(srctree)/Documentation/images/COPYING-logo $(objtree)/$(obj)/doc
 	$(Q)find $(objtree)/$(obj)/doc -name '*.html' -type f -print0 | xargs -0 sed -Ei \
 		-e 's:rust-logo\.svg:logo.svg:g' \
 		-e 's:rust-logo\.png:logo.svg:g' \
 		-e 's:favicon\.svg:logo.svg:g' \
 		-e 's:<link rel="alternate icon" type="image/png" href="[./]*favicon-(16x16|32x32)\.png">::g'
 	$(Q)echo '.logo-container > img { object-fit: contain; }' \
 		>> $(objtree)/$(obj)/doc/rustdoc.css

 rustdoc-macros: private rustdoc_host = yes
 rustdoc-macros: private rustc_target_flags = --crate-type proc-macro \
     --extern proc_macro
 rustdoc-macros: $(src)/macros/lib.rs FORCE
 	$(call if_changed,rustdoc)

 rustdoc-core: private rustc_target_flags = $(core-cfgs)
 rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
 	$(call if_changed,rustdoc)

 rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE
 	$(call if_changed,rustdoc)

 # We need to allow `rustdoc::broken_intra_doc_links` because some
 # `no_global_oom_handling` functions refer to non-`no_global_oom_handling`
 # functions. Ideally `rustdoc` would have a way to distinguish broken links
 # due to things that are "configured out" vs. entirely non-existing ones.
 rustdoc-alloc: private rustc_target_flags = $(alloc-cfgs) \
     -Arustdoc::broken_intra_doc_links
 rustdoc-alloc: $(src)/alloc/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE
 	$(call if_changed,rustdoc)

 rustdoc-kernel: private rustc_target_flags = --extern alloc \
     --extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so \
     --extern bindings
 rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \
     rustdoc-compiler_builtins rustdoc-alloc $(obj)/libmacros.so \
     $(obj)/bindings.o FORCE
 	$(call if_changed,rustdoc)

 quiet_cmd_rustc_test_library = RUSTC TL $<
       cmd_rustc_test_library = \
 	OBJTREE=$(abspath $(objtree)) \
 	$(RUSTC) $(rust_common_flags) \
 		@$(objtree)/include/generated/rustc_cfg $(rustc_target_flags) \
 		--crate-type $(if $(rustc_test_library_proc),proc-macro,rlib) \
 		--out-dir $(objtree)/$(obj)/test --cfg testlib \
 		--sysroot $(objtree)/$(obj)/test/sysroot \
 		-L$(objtree)/$(obj)/test \
 		--crate-name $(subst rusttest-,,$(subst rusttestlib-,,$@)) $<

 rusttestlib-build_error: $(src)/build_error.rs rusttest-prepare FORCE
 	$(call if_changed,rustc_test_library)

 rusttestlib-macros: private rustc_target_flags = --extern proc_macro
 rusttestlib-macros: private rustc_test_library_proc = yes
 rusttestlib-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
 	$(call if_changed,rustc_test_library)

 rusttestlib-bindings: $(src)/bindings/lib.rs rusttest-prepare FORCE
 	$(call if_changed,rustc_test_library)

 quiet_cmd_rustdoc_test = RUSTDOC T $<
       cmd_rustdoc_test = \
 	OBJTREE=$(abspath $(objtree)) \
 	$(RUSTDOC) --test $(rust_common_flags) \
 		@$(objtree)/include/generated/rustc_cfg \
 		$(rustc_target_flags) $(rustdoc_test_target_flags) \
 		--sysroot $(objtree)/$(obj)/test/sysroot $(rustdoc_test_quiet) \
 		-L$(objtree)/$(obj)/test --output $(objtree)/$(obj)/doc \
 		--crate-name $(subst rusttest-,,$@) $<

 # We cannot use `-Zpanic-abort-tests` because some tests are dynamic,
 # so for the moment we skip `-Cpanic=abort`.
 quiet_cmd_rustc_test = RUSTC T  $<
       cmd_rustc_test = \
 	OBJTREE=$(abspath $(objtree)) \
 	$(RUSTC) --test $(rust_common_flags) \
 		@$(objtree)/include/generated/rustc_cfg \
 		$(rustc_target_flags) --out-dir $(objtree)/$(obj)/test \
 		--sysroot $(objtree)/$(obj)/test/sysroot \
 		-L$(objtree)/$(obj)/test \
 		--crate-name $(subst rusttest-,,$@) $<; \
 	$(objtree)/$(obj)/test/$(subst rusttest-,,$@) $(rust_test_quiet) \
 		$(rustc_test_run_flags)

 rusttest: rusttest-macros rusttest-kernel

 # This prepares a custom sysroot with our custom `alloc` instead of
 # the standard one.
 #
 # This requires several hacks:
 #   - Unlike `core` and `alloc`, `std` depends on more than a dozen crates,
 #     including third-party crates that need to be downloaded, plus custom
 #     `build.rs` steps. Thus hardcoding things here is not maintainable.
 #   - `cargo` knows how to build the standard library, but it is an unstable
 #     feature so far (`-Zbuild-std`).
 #   - `cargo` only considers the use case of building the standard library
 #     to use it in a given package. Thus we need to create a dummy package
 #     and pick the generated libraries from there.
 #   - Since we only keep a subset of upstream `alloc` in-tree, we need
 #     to recreate it on the fly by putting our sources on top.
 #   - The usual ways of modifying the dependency graph in `cargo` do not seem
 #     to apply for the `-Zbuild-std` steps, thus we have to mislead it
 #     by modifying the sources in the sysroot.
 #   - To avoid messing with the user's Rust installation, we create a clone
 #     of the sysroot. However, `cargo` ignores `RUSTFLAGS` in the `-Zbuild-std`
 #     steps, thus we use a wrapper binary passed via `RUSTC` to pass the flag.
 #
 # In the future, we hope to avoid the whole ordeal by either:
 #   - Making the `test` crate not depend on `std` (either improving upstream
 #     or having our own custom crate).
 #   - Making the tests run in kernel space (requires the previous point).
 #   - Making `std` and friends be more like a "normal" crate, so that
 #     `-Zbuild-std` and related hacks are not needed.
 quiet_cmd_rustsysroot = RUSTSYSROOT
       cmd_rustsysroot = \
 	rm -rf $(objtree)/$(obj)/test; \
 	mkdir -p $(objtree)/$(obj)/test; \
 	cp -a $(rustc_sysroot) $(objtree)/$(obj)/test/sysroot; \
 	cp -r $(srctree)/$(src)/alloc/* \
 		$(objtree)/$(obj)/test/sysroot/lib/rustlib/src/rust/library/alloc/src; \
 	echo '\#!/bin/sh' > $(objtree)/$(obj)/test/rustc_sysroot; \
 	echo "$(RUSTC) --sysroot=$(abspath $(objtree)/$(obj)/test/sysroot) \"\$$@\"" \
 		>> $(objtree)/$(obj)/test/rustc_sysroot; \
 	chmod u+x $(objtree)/$(obj)/test/rustc_sysroot; \
 	$(CARGO) -q new $(objtree)/$(obj)/test/dummy; \
 	RUSTC=$(objtree)/$(obj)/test/rustc_sysroot $(CARGO) $(cargo_quiet) \
 		test -Zbuild-std --target $(rustc_host_target) \
 		--manifest-path $(objtree)/$(obj)/test/dummy/Cargo.toml; \
 	rm $(objtree)/$(obj)/test/sysroot/lib/rustlib/$(rustc_host_target)/lib/*; \
 	cp $(objtree)/$(obj)/test/dummy/target/$(rustc_host_target)/debug/deps/* \
 		$(objtree)/$(obj)/test/sysroot/lib/rustlib/$(rustc_host_target)/lib

 rusttest-prepare: FORCE
 	$(call if_changed,rustsysroot)

 rusttest-macros: private rustc_target_flags = --extern proc_macro
 rusttest-macros: private rustdoc_test_target_flags = --crate-type proc-macro
 rusttest-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
 	$(call if_changed,rustc_test)
 	$(call if_changed,rustdoc_test)

 rusttest-kernel: private rustc_target_flags = --extern alloc \
     --extern build_error --extern macros --extern bindings
 rusttest-kernel: $(src)/kernel/lib.rs rusttest-prepare \
     rusttestlib-build_error rusttestlib-macros rusttestlib-bindings FORCE
 	$(call if_changed,rustc_test)
 	$(call if_changed,rustc_test_library)

 filechk_rust_target = $(objtree)/scripts/generate_rust_target < $<

 $(obj)/target.json: $(objtree)/include/config/auto.conf FORCE
 	$(call filechk,rust_target)

 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 \
 	-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 \
 	--param=% --param asan-%

 # Derived from `scripts/Makefile.clang`.
 BINDGEN_TARGET_x86	:= x86_64-linux-gnu
 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)

 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

 bindgen_c_flags_final = $(bindgen_c_flags_lto) -D__BINDGEN__

 quiet_cmd_bindgen = BINDGEN $@
       cmd_bindgen = \
 	$(BINDGEN) $< $(bindgen_target_flags) \
 		--use-core --with-derive-default --ctypes-prefix core::ffi --no-layout-tests \
 		--no-debug '.*' \
 		--size_t-is-usize -o $@ -- $(bindgen_c_flags_final) -DMODULE \
 		$(bindgen_target_cflags) $(bindgen_target_extra)

 $(obj)/bindings/bindings_generated.rs: private bindgen_target_flags = \
     $(shell grep -v '^\#\|^$$' $(srctree)/$(src)/bindgen_parameters)
 $(obj)/bindings/bindings_generated.rs: $(src)/bindings/bindings_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 = \
     --blacklist-type '.*' --whitelist-var '' \
     --whitelist-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.c FORCE
 	$(call if_changed_dep,bindgen)

 quiet_cmd_exports = EXPORTS $@
       cmd_exports = \
 	$(NM) -p --defined-only $< \
 		| grep -E ' (T|R|D) ' | cut -d ' ' -f 3 \
 		| xargs -Isymbol \
 		echo 'EXPORT_SYMBOL_RUST_GPL(symbol);' > $@

 $(obj)/exports_core_generated.h: $(obj)/core.o FORCE
 	$(call if_changed,exports)

 $(obj)/exports_alloc_generated.h: $(obj)/alloc.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_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
       cmd_rustc_procmacro = \
 	$(RUSTC_OR_CLIPPY) $(rust_common_flags) \
 		--emit=dep-info,link --extern proc_macro \
 		--crate-type proc-macro --out-dir $(objtree)/$(obj) \
 		--crate-name $(patsubst lib%.so,%,$(notdir $@)) $<; \
 	mv $(objtree)/$(obj)/$(patsubst lib%.so,%,$(notdir $@)).d $(depfile); \
 	sed -i '/^\#/d' $(depfile)

 # Procedural macros can only be used with the `rustc` that compiled it.
 # Therefore, to get `libmacros.so` automatically recompiled when the compiler
 # version changes, we add `core.o` as a dependency (even if it is not needed).
 $(obj)/libmacros.so: $(src)/macros/lib.rs $(obj)/core.o FORCE
 	$(call if_changed_dep,rustc_procmacro)

 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,obj,metadata --crate-type rlib \
 		--out-dir $(objtree)/$(obj) -L$(objtree)/$(obj) \
 		--crate-name $(patsubst %.o,%,$(notdir $@)) $<; \
 	mv $(objtree)/$(obj)/$(patsubst %.o,%,$(notdir $@)).d $(depfile); \
 	sed -i '/^\#/d' $(depfile) \
 	$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@)

 rust-analyzer:
 	$(Q)$(srctree)/scripts/generate_rust_analyzer.py $(srctree) $(objtree) \
 		$(RUST_LIB_SRC) > $(objtree)/rust-project.json

 $(obj)/core.o: private skip_clippy = 1
 $(obj)/core.o: private skip_flags = -Dunreachable_pub
 $(obj)/core.o: private rustc_target_flags = $(core-cfgs)
 $(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs $(obj)/target.json FORCE
 	$(call if_changed_dep,rustc_library)

 $(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
 $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
 	$(call if_changed_dep,rustc_library)

 $(obj)/alloc.o: private skip_clippy = 1
 $(obj)/alloc.o: private skip_flags = -Dunreachable_pub
 $(obj)/alloc.o: private rustc_target_flags = $(alloc-cfgs)
 $(obj)/alloc.o: $(src)/alloc/lib.rs $(obj)/compiler_builtins.o FORCE
 	$(call if_changed_dep,rustc_library)

 $(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
 	$(call if_changed_dep,rustc_library)

 $(obj)/bindings.o: $(src)/bindings/lib.rs \
     $(obj)/compiler_builtins.o \
     $(obj)/bindings/bindings_generated.rs \
     $(obj)/bindings/bindings_helpers_generated.rs FORCE
 	$(call if_changed_dep,rustc_library)

 $(obj)/kernel.o: private rustc_target_flags = --extern alloc \
     --extern build_error --extern macros --extern bindings
 $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \
     $(obj)/libmacros.so $(obj)/bindings.o FORCE
 	$(call if_changed_dep,rustc_library)

 endif # CONFIG_RUST
	# SPDX-License-Identifier: GPL-2.0

	always-$(CONFIG_RUST) += target.json
	no-clean-files += target.json

	obj-$(CONFIG_RUST) += core.o compiler_builtins.o
	always-$(CONFIG_RUST) += exports_core_generated.h

	# Missing prototypes are expected in the helpers since these are exported
	# for Rust only, thus there is no header nor prototypes.
	obj-$(CONFIG_RUST) += helpers.o
	CFLAGS_REMOVE_helpers.o = -Wmissing-prototypes -Wmissing-declarations

	always-$(CONFIG_RUST) += libmacros.so
	no-clean-files += libmacros.so

	always-$(CONFIG_RUST) += bindings/bindings_generated.rs bindings/bindings_helpers_generated.rs
	obj-$(CONFIG_RUST) += alloc.o bindings.o kernel.o
	always-$(CONFIG_RUST) += exports_alloc_generated.h exports_bindings_generated.h \
	exports_kernel_generated.h

	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

	# Avoids running `$(RUSTC)` for the sysroot when it may not be available.
	ifdef CONFIG_RUST

	# `$(rust_flags)` is passed in case the user added `--sysroot`.
	rustc_sysroot := $(shell $(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

	ifeq ($(quiet),silent_)
	cargo_quiet=-q
	rust_test_quiet=-q
	rustdoc_test_quiet=--test-args -q
	else ifeq ($(quiet),quiet_)
	rust_test_quiet=-q
	rustdoc_test_quiet=--test-args -q
	else
	cargo_quiet=--verbose
	endif

	core-cfgs = \
	--cfg no_fp_fmt_parse

	alloc-cfgs = \
	--cfg no_fmt \
	--cfg no_global_oom_handling \
	--cfg no_macros \
	--cfg no_rc \
	--cfg no_str \
	--cfg no_string \
	--cfg no_sync \
	--cfg no_thin

	quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
	cmd_rustdoc = \
	OBJTREE=$(abspath $(objtree)) \
	$(RUSTDOC) $(if $(rustdoc_host),$(rust_common_flags),$(rust_flags)) \
	$(rustc_target_flags) -L$(objtree)/$(obj) \
	--output $(objtree)/$(obj)/doc \
	--crate-name $(subst rustdoc-,,$@) \
	@$(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-alloc rustdoc-kernel
	$(Q)cp $(srctree)/Documentation/images/logo.svg $(objtree)/$(obj)/doc
	$(Q)cp $(srctree)/Documentation/images/COPYING-logo $(objtree)/$(obj)/doc
	$(Q)find $(objtree)/$(obj)/doc -name '*.html' -type f -print0 \| xargs -0 sed -Ei \
	-e 's:rust-logo\.svg:logo.svg:g' \
	-e 's:rust-logo\.png:logo.svg:g' \
	-e 's:favicon\.svg:logo.svg:g' \
	-e 's:<link rel="alternate icon" type="image/png" href="[./]*favicon-(16x16\|32x32)\.png">::g'
	$(Q)echo '.logo-container > img { object-fit: contain; }' \
	>> $(objtree)/$(obj)/doc/rustdoc.css

	rustdoc-macros: private rustdoc_host = yes
	rustdoc-macros: private rustc_target_flags = --crate-type proc-macro \
	--extern proc_macro
	rustdoc-macros: $(src)/macros/lib.rs FORCE
	$(call if_changed,rustdoc)

	rustdoc-core: private rustc_target_flags = $(core-cfgs)
	rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
	$(call if_changed,rustdoc)

	rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE
	$(call if_changed,rustdoc)

	# We need to allow `rustdoc::broken_intra_doc_links` because some
	# `no_global_oom_handling` functions refer to non-`no_global_oom_handling`
	# functions. Ideally `rustdoc` would have a way to distinguish broken links
	# due to things that are "configured out" vs. entirely non-existing ones.
	rustdoc-alloc: private rustc_target_flags = $(alloc-cfgs) \
	-Arustdoc::broken_intra_doc_links
	rustdoc-alloc: $(src)/alloc/lib.rs rustdoc-core rustdoc-compiler_builtins FORCE
	$(call if_changed,rustdoc)

	rustdoc-kernel: private rustc_target_flags = --extern alloc \
	--extern build_error --extern macros=$(objtree)/$(obj)/libmacros.so \
	--extern bindings
	rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \
	rustdoc-compiler_builtins rustdoc-alloc $(obj)/libmacros.so \
	$(obj)/bindings.o FORCE
	$(call if_changed,rustdoc)

	quiet_cmd_rustc_test_library = RUSTC TL $<
	cmd_rustc_test_library = \
	OBJTREE=$(abspath $(objtree)) \
	$(RUSTC) $(rust_common_flags) \
	@$(objtree)/include/generated/rustc_cfg $(rustc_target_flags) \
	--crate-type $(if $(rustc_test_library_proc),proc-macro,rlib) \
	--out-dir $(objtree)/$(obj)/test --cfg testlib \
	--sysroot $(objtree)/$(obj)/test/sysroot \
	-L$(objtree)/$(obj)/test \
	--crate-name $(subst rusttest-,,$(subst rusttestlib-,,$@)) $<

	rusttestlib-build_error: $(src)/build_error.rs rusttest-prepare FORCE
	$(call if_changed,rustc_test_library)

	rusttestlib-macros: private rustc_target_flags = --extern proc_macro
	rusttestlib-macros: private rustc_test_library_proc = yes
	rusttestlib-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
	$(call if_changed,rustc_test_library)

	rusttestlib-bindings: $(src)/bindings/lib.rs rusttest-prepare FORCE
	$(call if_changed,rustc_test_library)

	quiet_cmd_rustdoc_test = RUSTDOC T $<
	cmd_rustdoc_test = \
	OBJTREE=$(abspath $(objtree)) \
	$(RUSTDOC) --test $(rust_common_flags) \
	@$(objtree)/include/generated/rustc_cfg \
	$(rustc_target_flags) $(rustdoc_test_target_flags) \
	--sysroot $(objtree)/$(obj)/test/sysroot $(rustdoc_test_quiet) \
	-L$(objtree)/$(obj)/test --output $(objtree)/$(obj)/doc \
	--crate-name $(subst rusttest-,,$@) $<

	# We cannot use `-Zpanic-abort-tests` because some tests are dynamic,
	# so for the moment we skip `-Cpanic=abort`.
	quiet_cmd_rustc_test = RUSTC T $<
	cmd_rustc_test = \
	OBJTREE=$(abspath $(objtree)) \
	$(RUSTC) --test $(rust_common_flags) \
	@$(objtree)/include/generated/rustc_cfg \
	$(rustc_target_flags) --out-dir $(objtree)/$(obj)/test \
	--sysroot $(objtree)/$(obj)/test/sysroot \
	-L$(objtree)/$(obj)/test \
	--crate-name $(subst rusttest-,,$@) $<; \
	$(objtree)/$(obj)/test/$(subst rusttest-,,$@) $(rust_test_quiet) \
	$(rustc_test_run_flags)

	rusttest: rusttest-macros rusttest-kernel

	# This prepares a custom sysroot with our custom `alloc` instead of
	# the standard one.
	#
	# This requires several hacks:
	# - Unlike `core` and `alloc`, `std` depends on more than a dozen crates,
	# including third-party crates that need to be downloaded, plus custom
	# `build.rs` steps. Thus hardcoding things here is not maintainable.
	# - `cargo` knows how to build the standard library, but it is an unstable
	# feature so far (`-Zbuild-std`).
	# - `cargo` only considers the use case of building the standard library
	# to use it in a given package. Thus we need to create a dummy package
	# and pick the generated libraries from there.
	# - Since we only keep a subset of upstream `alloc` in-tree, we need
	# to recreate it on the fly by putting our sources on top.
	# - The usual ways of modifying the dependency graph in `cargo` do not seem
	# to apply for the `-Zbuild-std` steps, thus we have to mislead it
	# by modifying the sources in the sysroot.
	# - To avoid messing with the user's Rust installation, we create a clone
	# of the sysroot. However, `cargo` ignores `RUSTFLAGS` in the `-Zbuild-std`
	# steps, thus we use a wrapper binary passed via `RUSTC` to pass the flag.
	#
	# In the future, we hope to avoid the whole ordeal by either:
	# - Making the `test` crate not depend on `std` (either improving upstream
	# or having our own custom crate).
	# - Making the tests run in kernel space (requires the previous point).
	# - Making `std` and friends be more like a "normal" crate, so that
	# `-Zbuild-std` and related hacks are not needed.
	quiet_cmd_rustsysroot = RUSTSYSROOT
	cmd_rustsysroot = \
	rm -rf $(objtree)/$(obj)/test; \
	mkdir -p $(objtree)/$(obj)/test; \
	cp -a $(rustc_sysroot) $(objtree)/$(obj)/test/sysroot; \
	cp -r $(srctree)/$(src)/alloc/* \
	$(objtree)/$(obj)/test/sysroot/lib/rustlib/src/rust/library/alloc/src; \
	echo '\#!/bin/sh' > $(objtree)/$(obj)/test/rustc_sysroot; \
	echo "$(RUSTC) --sysroot=$(abspath $(objtree)/$(obj)/test/sysroot) \"\$$@\"" \
	>> $(objtree)/$(obj)/test/rustc_sysroot; \
	chmod u+x $(objtree)/$(obj)/test/rustc_sysroot; \
	$(CARGO) -q new $(objtree)/$(obj)/test/dummy; \
	RUSTC=$(objtree)/$(obj)/test/rustc_sysroot $(CARGO) $(cargo_quiet) \
	test -Zbuild-std --target $(rustc_host_target) \
	--manifest-path $(objtree)/$(obj)/test/dummy/Cargo.toml; \
	rm $(objtree)/$(obj)/test/sysroot/lib/rustlib/$(rustc_host_target)/lib/*; \
	cp $(objtree)/$(obj)/test/dummy/target/$(rustc_host_target)/debug/deps/* \
	$(objtree)/$(obj)/test/sysroot/lib/rustlib/$(rustc_host_target)/lib

	rusttest-prepare: FORCE
	$(call if_changed,rustsysroot)

	rusttest-macros: private rustc_target_flags = --extern proc_macro
	rusttest-macros: private rustdoc_test_target_flags = --crate-type proc-macro
	rusttest-macros: $(src)/macros/lib.rs rusttest-prepare FORCE
	$(call if_changed,rustc_test)
	$(call if_changed,rustdoc_test)

	rusttest-kernel: private rustc_target_flags = --extern alloc \
	--extern build_error --extern macros --extern bindings
	rusttest-kernel: $(src)/kernel/lib.rs rusttest-prepare \
	rusttestlib-build_error rusttestlib-macros rusttestlib-bindings FORCE
	$(call if_changed,rustc_test)
	$(call if_changed,rustc_test_library)

	filechk_rust_target = $(objtree)/scripts/generate_rust_target < $<

	$(obj)/target.json: $(objtree)/include/config/auto.conf FORCE
	$(call filechk,rust_target)

	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 \
	-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 \
	--param=% --param asan-%

	# Derived from `scripts/Makefile.clang`.
	BINDGEN_TARGET_x86 := x86_64-linux-gnu
	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)

	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

	bindgen_c_flags_final = $(bindgen_c_flags_lto) -D__BINDGEN__

	quiet_cmd_bindgen = BINDGEN $@
	cmd_bindgen = \
	$(BINDGEN) $< $(bindgen_target_flags) \
	--use-core --with-derive-default --ctypes-prefix core::ffi --no-layout-tests \
	--no-debug '.*' \
	--size_t-is-usize -o $@ -- $(bindgen_c_flags_final) -DMODULE \
	$(bindgen_target_cflags) $(bindgen_target_extra)

	$(obj)/bindings/bindings_generated.rs: private bindgen_target_flags = \
	$(shell grep -v '^\#\\|^$$' $(srctree)/$(src)/bindgen_parameters)
	$(obj)/bindings/bindings_generated.rs: $(src)/bindings/bindings_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 = \
	--blacklist-type '.*' --whitelist-var '' \
	--whitelist-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.c FORCE
	$(call if_changed_dep,bindgen)

	quiet_cmd_exports = EXPORTS $@
	cmd_exports = \
	$(NM) -p --defined-only $< \
	\| grep -E ' (T\|R\|D) ' \| cut -d ' ' -f 3 \
	\| xargs -Isymbol \
	echo 'EXPORT_SYMBOL_RUST_GPL(symbol);' > $@

	$(obj)/exports_core_generated.h: $(obj)/core.o FORCE
	$(call if_changed,exports)

	$(obj)/exports_alloc_generated.h: $(obj)/alloc.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_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
	cmd_rustc_procmacro = \
	$(RUSTC_OR_CLIPPY) $(rust_common_flags) \
	--emit=dep-info,link --extern proc_macro \
	--crate-type proc-macro --out-dir $(objtree)/$(obj) \
	--crate-name $(patsubst lib%.so,%,$(notdir $@)) $<; \
	mv $(objtree)/$(obj)/$(patsubst lib%.so,%,$(notdir $@)).d $(depfile); \
	sed -i '/^\#/d' $(depfile)

	# Procedural macros can only be used with the `rustc` that compiled it.
	# Therefore, to get `libmacros.so` automatically recompiled when the compiler
	# version changes, we add `core.o` as a dependency (even if it is not needed).
	$(obj)/libmacros.so: $(src)/macros/lib.rs $(obj)/core.o FORCE
	$(call if_changed_dep,rustc_procmacro)

	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,obj,metadata --crate-type rlib \
	--out-dir $(objtree)/$(obj) -L$(objtree)/$(obj) \
	--crate-name $(patsubst %.o,%,$(notdir $@)) $<; \
	mv $(objtree)/$(obj)/$(patsubst %.o,%,$(notdir $@)).d $(depfile); \
	sed -i '/^\#/d' $(depfile) \
	$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@)

	rust-analyzer:
	$(Q)$(srctree)/scripts/generate_rust_analyzer.py $(srctree) $(objtree) \
	$(RUST_LIB_SRC) > $(objtree)/rust-project.json

	$(obj)/core.o: private skip_clippy = 1
	$(obj)/core.o: private skip_flags = -Dunreachable_pub
	$(obj)/core.o: private rustc_target_flags = $(core-cfgs)
	$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs $(obj)/target.json FORCE
	$(call if_changed_dep,rustc_library)

	$(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
	$(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE
	$(call if_changed_dep,rustc_library)

	$(obj)/alloc.o: private skip_clippy = 1
	$(obj)/alloc.o: private skip_flags = -Dunreachable_pub
	$(obj)/alloc.o: private rustc_target_flags = $(alloc-cfgs)
	$(obj)/alloc.o: $(src)/alloc/lib.rs $(obj)/compiler_builtins.o FORCE
	$(call if_changed_dep,rustc_library)

	$(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
	$(call if_changed_dep,rustc_library)

	$(obj)/bindings.o: $(src)/bindings/lib.rs \
	$(obj)/compiler_builtins.o \
	$(obj)/bindings/bindings_generated.rs \
	$(obj)/bindings/bindings_helpers_generated.rs FORCE
	$(call if_changed_dep,rustc_library)

	$(obj)/kernel.o: private rustc_target_flags = --extern alloc \
	--extern build_error --extern macros --extern bindings
	$(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \
	$(obj)/libmacros.so $(obj)/bindings.o FORCE
	$(call if_changed_dep,rustc_library)

	endif # CONFIG_RUST