rust: zerocopy: enable support in kbuild

With all the new files in place and ready from the new crate, enable
the support for it in the build system.

In addition, skip formatting for this vendored crate.

Finally, there are no generated symbols expected from `zerocopy`, thus
skip adding the `exports` generation.

Link: https://patch.msgid.link/20260608141439.182634-13-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Makefile

@@ -1956,6 +1956,7 @@ rustfmt:
 			-path $(srctree)/rust/proc-macro2 \
 			-o -path $(srctree)/rust/quote \
 			-o -path $(srctree)/rust/syn \
+			-o -path $(srctree)/rust/zerocopy \
 		\) -prune -o \
 		-type f -a -name '*.rs' -a ! -name '*generated*' -print \
 		| xargs $(RUSTFMT) $(rustfmt_flags)

rust/Makefile

@@ -6,6 +6,8 @@ rustdoc_output := $(objtree)/Documentation/output/rust/rustdoc
 obj-$(CONFIG_RUST) += core.o compiler_builtins.o ffi.o
 always-$(CONFIG_RUST) += exports_core_generated.h
 
+obj-$(CONFIG_RUST) += zerocopy.o
+
 ifdef CONFIG_RUST_INLINE_HELPERS
 always-$(CONFIG_RUST) += helpers/helpers.bc helpers/helpers_module.bc
 else
@@ -81,6 +83,12 @@ core-flags := \
     --edition=$(core-edition) \
     $(call cfgs-to-flags,$(core-cfgs))
 
+zerocopy-flags := \
+    --cap-lints=allow
+
+zerocopy-envs := \
+    CARGO_PKG_VERSION=0.8.50
+
 proc_macro2-cfgs := \
     feature="proc-macro" \
     wrap_proc_macro \
@@ -167,7 +175,7 @@ quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
 # 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
+    rustdoc-kernel rustdoc-pin_init rustdoc-zerocopy
 	$(Q)grep -Ehro '<a href="srctree/([^"]+)"' $(rustdoc_output) | \
 		cut -d'"' -f2 | cut -d/ -f2- | while read f; do \
 			if [ ! -e "$(srctree)/$$f" ]; then \
@@ -219,6 +227,13 @@ rustdoc-compiler_builtins: private is-kernel-object := y
 rustdoc-compiler_builtins: $(src)/compiler_builtins.rs rustdoc-core FORCE
 	+$(call if_changed,rustdoc)
 
+rustdoc-zerocopy: private rustc_target_envs := $(zerocopy-envs)
+rustdoc-zerocopy: private is-kernel-object := y
+rustdoc-zerocopy: private rustc_target_flags = $(zerocopy-flags) \
+    --extend-css $(src)/zerocopy/rustdoc/style.css
+rustdoc-zerocopy: $(src)/zerocopy/src/lib.rs rustdoc-clean rustdoc-core FORCE
+	+$(call if_changed,rustdoc)
+
 rustdoc-ffi: private is-kernel-object := y
 rustdoc-ffi: $(src)/ffi.rs rustdoc-core FORCE
 	+$(call if_changed,rustdoc)
@@ -240,7 +255,8 @@ rustdoc-pin_init: $(src)/pin-init/src/lib.rs rustdoc-pin_init_internal \
 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
+    --extern bindings --extern uapi \
+    --extern zerocopy
 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
@@ -260,6 +276,11 @@ quiet_cmd_rustc_test_library = $(RUSTC_OR_CLIPPY_QUIET) TL $<
 		-L$(objtree)/$(obj)/test \
 		--crate-name $(subst rusttest-,,$(subst rusttestlib-,,$@)) $<
 
+rusttestlib-zerocopy: private rustc_target_envs := $(zerocopy-envs)
+rusttestlib-zerocopy: private rustc_target_flags = $(zerocopy-flags)
+rusttestlib-zerocopy: $(src)/zerocopy/src/lib.rs FORCE
+	+$(call if_changed,rustc_test_library)
+
 rusttestlib-build_error: $(src)/build_error.rs FORCE
 	+$(call if_changed,rustc_test_library)
 
@@ -300,10 +321,11 @@ rusttestlib-pin_init: $(src)/pin-init/src/lib.rs rusttestlib-macros \
 
 rusttestlib-kernel: private rustc_target_flags = --extern ffi \
     --extern build_error --extern macros --extern pin_init \
-    --extern bindings --extern uapi
+    --extern bindings --extern uapi \
+    --extern zerocopy
 rusttestlib-kernel: $(src)/kernel/lib.rs rusttestlib-bindings rusttestlib-uapi \
     rusttestlib-build_error rusttestlib-pin_init $(obj)/$(libmacros_name) \
-    $(obj)/bindings.o FORCE
+    $(obj)/bindings.o rusttestlib-zerocopy FORCE
 	+$(call if_changed,rustc_test_library)
 
 rusttestlib-bindings: private rustc_target_flags = --extern ffi --extern pin_init
@@ -337,6 +359,7 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $<
 		-L$(objtree)/$(obj) --extern ffi --extern pin_init \
 		--extern kernel --extern build_error --extern macros \
 		--extern bindings --extern uapi \
+		--extern zerocopy \
 		--no-run --crate-name kernel -Zunstable-options \
 		--sysroot=/dev/null \
 		$(doctests_modifiers_workaround) \
@@ -599,6 +622,7 @@ rust-analyzer:
 		--cfgs='syn=$(syn-cfgs)' \
 		--cfgs='pin_init_internal=$(pin_init_internal-cfgs)' \
 		--cfgs='pin_init=$(pin_init-cfgs)' \
+		--envs='zerocopy=$(zerocopy-envs)' \
 		$(realpath $(srctree)) $(realpath $(objtree)) \
 		$(rustc_sysroot) $(RUST_LIB_SRC) $(if $(KBUILD_EXTMOD),$(srcroot)) \
 		> rust-project.json
@@ -670,6 +694,13 @@ $(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)
 
+$(obj)/zerocopy.o: private skip_clippy = 1
+$(obj)/zerocopy.o: private skip_gendwarfksyms = 1
+$(obj)/zerocopy.o: private rustc_target_envs := $(zerocopy-envs)
+$(obj)/zerocopy.o: private rustc_target_flags = $(zerocopy-flags)
+$(obj)/zerocopy.o: $(src)/zerocopy/src/lib.rs $(obj)/compiler_builtins.o FORCE
+	+$(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 \
@@ -705,9 +736,11 @@ $(obj)/uapi.o: $(src)/uapi/lib.rs \
 	+$(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
+    --extern build_error --extern macros --extern bindings --extern uapi \
+    --extern zerocopy
 $(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
+    $(obj)/$(libmacros_name) $(obj)/bindings.o $(obj)/uapi.o \
+    $(obj)/zerocopy.o FORCE
 	+$(call if_changed_rule,rustc_library)
 
 ifdef CONFIG_JUMP_LABEL

scripts/Makefile.build

@@ -329,6 +329,7 @@ rust_common_cmd = \
 	-Zcrate-attr=no_std \
 	-Zcrate-attr='feature($(rust_allowed_features))' \
 	-Zunstable-options --extern pin_init --extern kernel \
+	--extern zerocopy \
 	--crate-type rlib -L $(objtree)/rust/ \
 	--sysroot=/dev/null \
 	--out-dir $(dir $@) --emit=dep-info=$(depfile)

scripts/generate_rust_analyzer.py

@@ -276,6 +276,12 @@ def generate_crates(
         [core, compiler_builtins],
     )
 
+    zerocopy = append_crate(
+        "zerocopy",
+        srctree / "rust" / "zerocopy" / "src" / "lib.rs",
+        [core, compiler_builtins],
+    )
+
     def append_crate_with_generated(
         display_name: str,
         deps: List[Dependency],
@@ -304,7 +310,7 @@ def generate_crates(
     bindings = append_crate_with_generated("bindings", [core, ffi, pin_init])
     uapi = append_crate_with_generated("uapi", [core, ffi, pin_init])
     kernel = append_crate_with_generated(
-        "kernel", [core, macros, build_error, pin_init, ffi, bindings, uapi]
+        "kernel", [core, macros, build_error, pin_init, ffi, bindings, uapi, zerocopy]
     )
 
     scripts = srctree / "scripts"
@@ -349,7 +355,7 @@ def generate_crates(
             append_crate(
                 crate_name,
                 path,
-                [core, kernel, pin_init],
+                [core, kernel, pin_init, zerocopy],
                 cfg=generated_cfg,
             )