Add XArray abstraction

Documentation/process/changes.rst

@@ -32,7 +32,7 @@ you probably needn't concern yourself with pcmciautils.
 GNU C                  5.1              gcc --version
 Clang/LLVM (optional)  11.0.0           clang --version
 Rust (optional)        1.68.2           rustc --version
-bindgen (optional)     0.56.0           bindgen --version
+bindgen (optional)     0.65.1           bindgen --version
 GNU make               3.82             make --version
 bash                   4.2              bash --version
 binutils               2.25             ld -v

Documentation/rust/arch-support.rst

@@ -15,6 +15,7 @@ support corresponds to ``S`` values in the ``MAINTAINERS`` file.
 ============  ================  ==============================================
 Architecture  Level of support  Constraints
 ============  ================  ==============================================
+``arm64``     Maintained        Little Endian only.
 ``um``        Maintained        ``x86_64`` only.
 ``x86``       Maintained        ``x86_64`` only.
 ============  ================  ==============================================

Documentation/rust/quick-start.rst

@@ -98,7 +98,24 @@ the ``bindgen`` tool. A particular version is required.
 
 Install it via (note that this will download and build the tool from source)::
 
-	cargo install --locked --version $(scripts/min-tool-version.sh bindgen) bindgen
+	cargo install --locked --version $(scripts/min-tool-version.sh bindgen) bindgen-cli
+
+``bindgen`` needs to find a suitable ``libclang`` in order to work. If it is
+not found (or a different ``libclang`` than the one found should be used),
+the process can be tweaked using the environment variables understood by
+``clang-sys`` (the Rust bindings crate that ``bindgen`` uses to access
+``libclang``):
+
+* ``LLVM_CONFIG_PATH`` can be pointed to an ``llvm-config`` executable.
+
+* Or ``LIBCLANG_PATH`` can be pointed to a ``libclang`` shared library
+  or to the directory containing it.
+
+* Or ``CLANG_PATH`` can be pointed to a ``clang`` executable.
+
+For details, please see ``clang-sys``'s documentation at:
+
+	https://github.com/KyleMayes/clang-sys#environment-variables
 
 
 Requirements: Developing

MAINTAINERS

@@ -11323,6 +11323,8 @@ W:	https://google.github.io/kunit-docs/third_party/kernel/docs/
 F:	Documentation/dev-tools/kunit/
 F:	include/kunit/
 F:	lib/kunit/
+F:	rust/kernel/kunit.rs
+F:	scripts/rustdoc_test_*
 F:	tools/testing/kunit/
 
 KERNEL USERMODE HELPER

Makefile

@@ -561,7 +561,6 @@ KBUILD_CFLAGS   := -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs \
 		   -std=gnu11
 KBUILD_CPPFLAGS := -D__KERNEL__
 KBUILD_RUSTFLAGS := $(rust_common_flags) \
-		    --target=$(objtree)/scripts/target.json \
 		    -Cpanic=abort -Cembed-bitcode=n -Clto=n \
 		    -Cforce-unwind-tables=n -Ccodegen-units=1 \
 		    -Csymbol-mangling-version=v0 \
@@ -1289,7 +1288,7 @@ prepare0: archprepare
 # All the preparing..
 prepare: prepare0
 ifdef CONFIG_RUST
-	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh -v
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
 	$(Q)$(MAKE) $(build)=rust
 endif
 
@@ -1823,7 +1822,7 @@ $(DOC_TARGETS):
 # "Is Rust available?" target
 PHONY += rustavailable
 rustavailable:
-	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh -v && echo "Rust is available!"
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh && echo "Rust is available!"
 
 # Documentation target
 #

arch/arm64/Kconfig

@@ -217,6 +217,7 @@ config ARM64
 	select HAVE_FUNCTION_ARG_ACCESS_API
 	select MMU_GATHER_RCU_TABLE_FREE
 	select HAVE_RSEQ
+	select HAVE_RUST if CPU_LITTLE_ENDIAN
 	select HAVE_STACKPROTECTOR
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HAVE_KPROBES

arch/arm64/Makefile

@@ -41,6 +41,8 @@ KBUILD_CFLAGS	+= -mgeneral-regs-only	\
 KBUILD_CFLAGS	+= $(call cc-disable-warning, psabi)
 KBUILD_AFLAGS	+= $(compat_vdso)
 
+KBUILD_RUSTFLAGS += --target aarch64-unknown-none -C target-feature="-neon,-fp-armv8"
+
 KBUILD_CFLAGS	+= $(call cc-option,-mabi=lp64)
 KBUILD_AFLAGS	+= $(call cc-option,-mabi=lp64)
 
@@ -65,7 +67,9 @@ endif
 
 ifeq ($(CONFIG_ARM64_BTI_KERNEL),y)
   KBUILD_CFLAGS += -mbranch-protection=pac-ret+bti
+  KBUILD_RUSTFLAGS += -Z branch-protection=bti,pac-ret
 else ifeq ($(CONFIG_ARM64_PTR_AUTH_KERNEL),y)
+  KBUILD_RUSTFLAGS += -Z branch-protection=pac-ret
   ifeq ($(CONFIG_CC_HAS_BRANCH_PROT_PAC_RET),y)
     KBUILD_CFLAGS += -mbranch-protection=pac-ret
   else

arch/x86/Makefile

@@ -68,6 +68,7 @@ export BITS
 #    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53383
 #
 KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx
+KBUILD_RUSTFLAGS += --target=$(objtree)/scripts/target.json
 KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2
 
 ifeq ($(CONFIG_X86_KERNEL_IBT),y)

lib/Kconfig.debug

@@ -2911,6 +2911,19 @@ config RUST_BUILD_ASSERT_ALLOW
 
 	  If unsure, say N.
 
+config RUST_KERNEL_KUNIT_TEST
+	bool "KUnit test for the `kernel` crate" if !KUNIT_ALL_TESTS
+	depends on RUST && KUNIT=y
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the documentation tests of the `kernel` crate
+	  as KUnit tests.
+
+	  For more information on KUnit and unit tests in general,
+	  please refer to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+	  If unsure, say N.
+
 endmenu # "Rust"
 
 endmenu # Kernel hacking

rust/.gitignore

@@ -2,6 +2,8 @@
 
 bindings_generated.rs
 bindings_helpers_generated.rs
+doctests_kernel_generated.rs
+doctests_kernel_generated_kunit.c
 uapi_generated.rs
 exports_*_generated.h
 doc/

rust/Makefile

@@ -27,6 +27,12 @@ endif
 
 obj-$(CONFIG_RUST) += exports.o
 
+always-$(CONFIG_RUST_KERNEL_KUNIT_TEST) += doctests_kernel_generated.rs
+always-$(CONFIG_RUST_KERNEL_KUNIT_TEST) += doctests_kernel_generated_kunit.c
+
+obj-$(CONFIG_RUST_KERNEL_KUNIT_TEST) += doctests_kernel_generated.o
+obj-$(CONFIG_RUST_KERNEL_KUNIT_TEST) += doctests_kernel_generated_kunit.o
+
 # Avoids running `$(RUSTC)` for the sysroot when it may not be available.
 ifdef CONFIG_RUST
 
@@ -39,9 +45,11 @@ ifeq ($(quiet),silent_)
 cargo_quiet=-q
 rust_test_quiet=-q
 rustdoc_test_quiet=--test-args -q
+rustdoc_test_kernel_quiet=>/dev/null
 else ifeq ($(quiet),quiet_)
 rust_test_quiet=-q
 rustdoc_test_quiet=--test-args -q
+rustdoc_test_kernel_quiet=>/dev/null
 else
 cargo_quiet=--verbose
 endif
@@ -157,6 +165,27 @@ quiet_cmd_rustdoc_test = RUSTDOC T $<
 		-L$(objtree)/$(obj)/test --output $(objtree)/$(obj)/doc \
 		--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 $(rust_flags) \
+		@$(objtree)/include/generated/rustc_cfg \
+		-L$(objtree)/$(obj) --extern alloc --extern kernel \
+		--extern build_error --extern macros \
+		--extern bindings --extern uapi \
+		--no-run --crate-name kernel -Zunstable-options \
+		--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 T  $<
@@ -262,6 +291,7 @@ bindgen_skip_c_flags := -mno-fp-ret-in-387 -mpreferred-stack-boundary=% \
 
 # Derived from `scripts/Makefile.clang`.
 BINDGEN_TARGET_x86	:= x86_64-linux-gnu
+BINDGEN_TARGET_arm64    := aarch64-linux-gnu
 BINDGEN_TARGET		:= $(BINDGEN_TARGET_$(SRCARCH))
 
 # All warnings are inhibited since GCC builds are very experimental,
@@ -300,7 +330,7 @@ quiet_cmd_bindgen = 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 \
+		-o $@ -- $(bindgen_c_flags_final) -DMODULE \
 		$(bindgen_target_cflags) $(bindgen_target_extra)
 
 $(obj)/bindings/bindings_generated.rs: private bindgen_target_flags = \
@@ -320,8 +350,8 @@ $(obj)/uapi/uapi_generated.rs: $(src)/uapi/uapi_helper.h \
 # 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_.*'
+    --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 = ; \
@@ -393,8 +423,11 @@ $(obj)/core.o: private skip_clippy = 1
 $(obj)/core.o: private skip_flags = -Dunreachable_pub
 $(obj)/core.o: private rustc_objcopy = $(foreach sym,$(redirect-intrinsics),--redefine-sym $(sym)=__rust$(sym))
 $(obj)/core.o: private rustc_target_flags = $(core-cfgs)
-$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs scripts/target.json FORCE
+$(obj)/core.o: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
 	$(call if_changed_dep,rustc_library)
+ifeq ($(ARCH),x86_64)
+$(obj)/core.o: scripts/target.json
+endif
 
 $(obj)/compiler_builtins.o: private rustc_objcopy = -w -W '__*'
 $(obj)/compiler_builtins.o: $(src)/compiler_builtins.rs $(obj)/core.o FORCE

rust/bindings/bindings_helper.h

@@ -6,12 +6,31 @@
  * Sorted alphabetically.
  */
 
+#include <kunit/test.h>
 #include <linux/errname.h>
 #include <linux/slab.h>
 #include <linux/refcount.h>
 #include <linux/wait.h>
 #include <linux/sched.h>
+#include <linux/xarray.h>
 
 /* `bindgen` gets confused at certain things. */
 const gfp_t BINDINGS_GFP_KERNEL = GFP_KERNEL;
 const gfp_t BINDINGS___GFP_ZERO = __GFP_ZERO;
+const size_t BINDINGS_ARCH_SLAB_MINALIGN = ARCH_SLAB_MINALIGN;
+
+const gfp_t BINDINGS_XA_FLAGS_LOCK_IRQ = XA_FLAGS_LOCK_IRQ;
+const gfp_t BINDINGS_XA_FLAGS_LOCK_BH = XA_FLAGS_LOCK_BH;
+const gfp_t BINDINGS_XA_FLAGS_TRACK_FREE = XA_FLAGS_TRACK_FREE;
+const gfp_t BINDINGS_XA_FLAGS_ZERO_BUSY = XA_FLAGS_ZERO_BUSY;
+const gfp_t BINDINGS_XA_FLAGS_ALLOC_WRAPPED = XA_FLAGS_ALLOC_WRAPPED;
+const gfp_t BINDINGS_XA_FLAGS_ACCOUNT = XA_FLAGS_ACCOUNT;
+const gfp_t BINDINGS_XA_FLAGS_ALLOC = XA_FLAGS_ALLOC;
+const gfp_t BINDINGS_XA_FLAGS_ALLOC1 = XA_FLAGS_ALLOC1;
+
+const xa_mark_t BINDINGS_XA_MARK_0 = XA_MARK_0;
+const xa_mark_t BINDINGS_XA_MARK_1 = XA_MARK_1;
+const xa_mark_t BINDINGS_XA_MARK_2 = XA_MARK_2;
+const xa_mark_t BINDINGS_XA_PRESENT = XA_PRESENT;
+const xa_mark_t BINDINGS_XA_MARK_MAX = XA_MARK_MAX;
+const xa_mark_t BINDINGS_XA_FREE_MARK = XA_FREE_MARK;

rust/helpers.c

@@ -18,6 +18,8 @@
  * accidentally exposed.
  */
 
+#include <linux/stddef.h>
+#include <kunit/test-bug.h>
 #include <linux/bug.h>
 #include <linux/build_bug.h>
 #include <linux/err.h>
@@ -27,6 +29,7 @@
 #include <linux/spinlock.h>
 #include <linux/sched/signal.h>
 #include <linux/wait.h>
+#include <linux/xarray.h>
 
 __noreturn void rust_helper_BUG(void)
 {
@@ -135,20 +138,60 @@ void rust_helper_put_task_struct(struct task_struct *t)
 }
 EXPORT_SYMBOL_GPL(rust_helper_put_task_struct);
 
+struct kunit *rust_helper_kunit_get_current_test(void)
+{
+	return kunit_get_current_test();
+}
+EXPORT_SYMBOL_GPL(rust_helper_kunit_get_current_test);
+void rust_helper_xa_init_flags(struct xarray *xa, gfp_t flags)
+{
+	xa_init_flags(xa, flags);
+}
+EXPORT_SYMBOL_GPL(rust_helper_xa_init_flags);
+
+bool rust_helper_xa_empty(struct xarray *xa)
+{
+	return xa_empty(xa);
+}
+EXPORT_SYMBOL_GPL(rust_helper_xa_empty);
+
+int rust_helper_xa_alloc(struct xarray *xa, u32 *id, void *entry, struct xa_limit limit, gfp_t gfp)
+{
+	return xa_alloc(xa, id, entry, limit, gfp);
+}
+EXPORT_SYMBOL_GPL(rust_helper_xa_alloc);
+
+void rust_helper_xa_lock(struct xarray *xa)
+{
+	xa_lock(xa);
+}
+EXPORT_SYMBOL_GPL(rust_helper_xa_lock);
+
+void rust_helper_xa_unlock(struct xarray *xa)
+{
+	xa_unlock(xa);
+}
+EXPORT_SYMBOL_GPL(rust_helper_xa_unlock);
+
+int rust_helper_xa_err(void *entry)
+{
+	return xa_err(entry);
+}
+EXPORT_SYMBOL_GPL(rust_helper_xa_err);
+
 /*
- * We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type
- * as the Rust `usize` type, so we can use it in contexts where Rust
- * expects a `usize` like slice (array) indices. `usize` is defined to be
- * the same as C's `uintptr_t` type (can hold any pointer) but not
- * necessarily the same as `size_t` (can hold the size of any single
+ * `bindgen` binds the C `size_t` type the Rust `usize` type, so we can
+ * use it in contexts where Rust expects a `usize` like slice (array) indices.
+ * `usize` is defined to be the same as C's `uintptr_t` type (can hold any pointer)
+ * but not necessarily the same as `size_t` (can hold the size of any single
  * object). Most modern platforms use the same concrete integer type for
  * both of them, but in case we find ourselves on a platform where
  * that's not true, fail early instead of risking ABI or
  * integer-overflow issues.
  *
  * If your platform fails this assertion, it means that you are in
- * danger of integer-overflow bugs (even if you attempt to remove
- * `--size_t-is-usize`). It may be easiest to change the kernel ABI on
+ * danger of integer-overflow bugs (even if you attempt to add
+ * `--no-size_t-is-usize`). It may be easiest to change the kernel ABI on
  * your platform such that `size_t` matches `uintptr_t` (i.e., to increase
  * `size_t`, because `uintptr_t` has to be at least as big as `size_t`).
  */