Merge tag 'rust-6.12' of https://github.com/Rust-for-Linux/linux

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
  ...

39 files changed, 3481 insertions, 326 deletions

diff --git a/rust/Makefile b/rust/Makefile
index f168d2c98a15..b5e0a73b78f3 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -8,16 +8,16 @@ 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-$(CONFIG_RUST) += helpers.o
-CFLAGS_REMOVE_helpers.o = -Wmissing-prototypes -Wmissing-declarations
+obj-$(CONFIG_RUST) += helpers/helpers.o
+CFLAGS_REMOVE_helpers/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-$(CONFIG_RUST) += exports_alloc_generated.h exports_bindings_generated.h \
-    exports_kernel_generated.h
+always-$(CONFIG_RUST) += exports_alloc_generated.h exports_helpers_generated.h \
+    exports_bindings_generated.h exports_kernel_generated.h
 
 always-$(CONFIG_RUST) += uapi/uapi_generated.rs
 obj-$(CONFIG_RUST) += uapi.o
@@ -63,6 +63,7 @@ quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
 	OBJTREE=$(abspath $(objtree)) \
 	$(RUSTDOC) $(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 $(subst rustdoc-,,$@) \
 		$(if $(rustdoc_host),,--sysroot=/dev/null) \
@@ -270,7 +271,7 @@ quiet_cmd_bindgen = BINDGEN $@
       cmd_bindgen = \
 	$(BINDGEN) $< $(bindgen_target_flags) \
 		--use-core --with-derive-default --ctypes-prefix core::ffi --no-layout-tests \
-		--no-debug '.*' \
+		--no-debug '.*' --enable-function-attribute-detection \
 		-o $@ -- $(bindgen_c_flags_final) -DMODULE \
 		$(bindgen_target_cflags) $(bindgen_target_extra)
 
@@ -299,13 +300,13 @@ $(obj)/bindings/bindings_helpers_generated.rs: private bindgen_target_cflags = \
     -I$(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: $(src)/helpers.c FORCE
+$(obj)/bindings/bindings_helpers_generated.rs: $(src)/helpers/helpers.c FORCE
 	$(call if_changed_dep,bindgen)
 
 quiet_cmd_exports = EXPORTS $@
       cmd_exports = \
 	$(NM) -p --defined-only $< \
-		| awk '/ (T|R|D|B) / {printf "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@
+		| awk '$$2~/(T|R|D|B)/ && $$3!~/__cfi/ {printf "EXPORT_SYMBOL_RUST_GPL(%s);\n",$$3}' > $@
 
 $(obj)/exports_core_generated.h: $(obj)/core.o FORCE
 	$(call if_changed,exports)
@@ -313,6 +314,18 @@ $(obj)/exports_core_generated.h: $(obj)/core.o FORCE
 $(obj)/exports_alloc_generated.h: $(obj)/alloc.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)
 
@@ -329,9 +342,7 @@ quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
 		--crate-name $(patsubst lib%.so,%,$(notdir $@)) $<
 
 # 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 $(obj)/core.o FORCE
+$(obj)/libmacros.so: $(src)/macros/lib.rs FORCE
 	+$(call if_changed_dep,rustc_procmacro)
 
 quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
@@ -344,7 +355,8 @@ quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L
 		--crate-type rlib -L$(objtree)/$(obj) \
 		--crate-name $(patsubst %.o,%,$(notdir $@)) $< \
 		--sysroot=/dev/null \
-	$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@)
+	$(if $(rustc_objcopy),;$(OBJCOPY) $(rustc_objcopy) $@) \
+	$(cmd_objtool)
 
 rust-analyzer:
 	$(Q)$(srctree)/scripts/generate_rust_analyzer.py \
@@ -366,44 +378,50 @@ ifneq ($(or $(CONFIG_ARM64),$(and $(CONFIG_RISCV),$(CONFIG_64BIT))),)
 		__ashlti3 __lshrti3
 endif
 
+define rule_rustc_library
+	$(call cmd_and_fixdep,rustc_library)
+	$(call cmd,gen_objtooldep)
+endef
+
 $(obj)/core.o: private skip_clippy = 1
 $(obj)/core.o: private skip_flags = -Wunreachable_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: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
-	+$(call if_changed_dep,rustc_library)
+$(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
 
 $(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)
+	+$(call if_changed_rule,rustc_library)
 
 $(obj)/alloc.o: private skip_clippy = 1
 $(obj)/alloc.o: private skip_flags = -Wunreachable_pub
 $(obj)/alloc.o: private rustc_target_flags = $(alloc-cfgs)
 $(obj)/alloc.o: $(RUST_LIB_SRC)/alloc/src/lib.rs $(obj)/compiler_builtins.o FORCE
-	+$(call if_changed_dep,rustc_library)
+	+$(call if_changed_rule,rustc_library)
 
 $(obj)/build_error.o: $(src)/build_error.rs $(obj)/compiler_builtins.o FORCE
-	+$(call if_changed_dep,rustc_library)
+	+$(call if_changed_rule,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)
+	+$(call if_changed_rule,rustc_library)
 
 $(obj)/uapi.o: $(src)/uapi/lib.rs \
     $(obj)/compiler_builtins.o \
     $(obj)/uapi/uapi_generated.rs FORCE
-	+$(call if_changed_dep,rustc_library)
+	+$(call if_changed_rule,rustc_library)
 
 $(obj)/kernel.o: private rustc_target_flags = --extern alloc \
     --extern build_error --extern macros --extern bindings --extern uapi
 $(obj)/kernel.o: $(src)/kernel/lib.rs $(obj)/alloc.o $(obj)/build_error.o \
     $(obj)/libmacros.so $(obj)/bindings.o $(obj)/uapi.o FORCE
-	+$(call if_changed_dep,rustc_library)
+	+$(call if_changed_rule,rustc_library)
 
 endif # CONFIG_RUST
diff --git a/rust/bindings/bindings_helper.h b/rust/bindings/bindings_helper.h
index b940a5777330..ae82e9c941af 100644
--- a/rust/bindings/bindings_helper.h
+++ b/rust/bindings/bindings_helper.h
@@ -7,8 +7,8 @@
  */
 
 #include <kunit/test.h>
-#include <linux/blk_types.h>
 #include <linux/blk-mq.h>
+#include <linux/blk_types.h>
 #include <linux/blkdev.h>
 #include <linux/errname.h>
 #include <linux/ethtool.h>
diff --git a/rust/exports.c b/rust/exports.c
index 3803c21d1403..e5695f3b45b7 100644
--- a/rust/exports.c
+++ b/rust/exports.c
@@ -17,6 +17,7 @@
 
 #include "exports_core_generated.h"
 #include "exports_alloc_generated.h"
+#include "exports_helpers_generated.h"
 #include "exports_bindings_generated.h"
 #include "exports_kernel_generated.h"
 
diff --git a/rust/helpers.c b/rust/helpers.c
deleted file mode 100644
index 92d3c03ae1bd..000000000000
--- a/rust/helpers.c
+++ /dev/null
@@ -1,239 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * Non-trivial C macros cannot be used in Rust. Similarly, inlined C functions
- * cannot be called either. This file explicitly creates functions ("helpers")
- * that wrap those so that they can be called from Rust.
- *
- * Even though Rust kernel modules should never use the bindings directly, some
- * of these 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, this file exports all the helpers. In the future, this may be
- * revisited to reduce the number of exports after the compiler is informed
- * about the places codegen is required.
- *
- * All symbols are exported as GPL-only to guarantee no GPL-only feature is
- * accidentally exposed.
- *
- * Sorted alphabetically.
- */
-
-#include <kunit/test-bug.h>
-#include <linux/bug.h>
-#include <linux/build_bug.h>
-#include <linux/device.h>
-#include <linux/err.h>
-#include <linux/errname.h>
-#include <linux/gfp.h>
-#include <linux/highmem.h>
-#include <linux/mutex.h>
-#include <linux/refcount.h>
-#include <linux/sched/signal.h>
-#include <linux/slab.h>
-#include <linux/spinlock.h>
-#include <linux/wait.h>
-#include <linux/workqueue.h>
-
-__noreturn void rust_helper_BUG(void)
-{
-	BUG();
-}
-EXPORT_SYMBOL_GPL(rust_helper_BUG);
-
-unsigned long rust_helper_copy_from_user(void *to, const void __user *from,
-					 unsigned long n)
-{
-	return copy_from_user(to, from, n);
-}
-EXPORT_SYMBOL_GPL(rust_helper_copy_from_user);
-
-unsigned long rust_helper_copy_to_user(void __user *to, const void *from,
-				       unsigned long n)
-{
-	return copy_to_user(to, from, n);
-}
-EXPORT_SYMBOL_GPL(rust_helper_copy_to_user);
-
-void rust_helper_mutex_lock(struct mutex *lock)
-{
-	mutex_lock(lock);
-}
-EXPORT_SYMBOL_GPL(rust_helper_mutex_lock);
-
-void rust_helper___spin_lock_init(spinlock_t *lock, const char *name,
-				  struct lock_class_key *key)
-{
-#ifdef CONFIG_DEBUG_SPINLOCK
-	__raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG);
-#else
-	spin_lock_init(lock);
-#endif
-}
-EXPORT_SYMBOL_GPL(rust_helper___spin_lock_init);
-
-void rust_helper_spin_lock(spinlock_t *lock)
-{
-	spin_lock(lock);
-}
-EXPORT_SYMBOL_GPL(rust_helper_spin_lock);
-
-void rust_helper_spin_unlock(spinlock_t *lock)
-{
-	spin_unlock(lock);
-}
-EXPORT_SYMBOL_GPL(rust_helper_spin_unlock);
-
-void rust_helper_init_wait(struct wait_queue_entry *wq_entry)
-{
-	init_wait(wq_entry);
-}
-EXPORT_SYMBOL_GPL(rust_helper_init_wait);
-
-int rust_helper_signal_pending(struct task_struct *t)
-{
-	return signal_pending(t);
-}
-EXPORT_SYMBOL_GPL(rust_helper_signal_pending);
-
-struct page *rust_helper_alloc_pages(gfp_t gfp_mask, unsigned int order)
-{
-	return alloc_pages(gfp_mask, order);
-}
-EXPORT_SYMBOL_GPL(rust_helper_alloc_pages);
-
-void *rust_helper_kmap_local_page(struct page *page)
-{
-	return kmap_local_page(page);
-}
-EXPORT_SYMBOL_GPL(rust_helper_kmap_local_page);
-
-void rust_helper_kunmap_local(const void *addr)
-{
-	kunmap_local(addr);
-}
-EXPORT_SYMBOL_GPL(rust_helper_kunmap_local);
-
-refcount_t rust_helper_REFCOUNT_INIT(int n)
-{
-	return (refcount_t)REFCOUNT_INIT(n);
-}
-EXPORT_SYMBOL_GPL(rust_helper_REFCOUNT_INIT);
-
-void rust_helper_refcount_inc(refcount_t *r)
-{
-	refcount_inc(r);
-}
-EXPORT_SYMBOL_GPL(rust_helper_refcount_inc);
-
-bool rust_helper_refcount_dec_and_test(refcount_t *r)
-{
-	return refcount_dec_and_test(r);
-}
-EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test);
-
-__force void *rust_helper_ERR_PTR(long err)
-{
-	return ERR_PTR(err);
-}
-EXPORT_SYMBOL_GPL(rust_helper_ERR_PTR);
-
-bool rust_helper_IS_ERR(__force const void *ptr)
-{
-	return IS_ERR(ptr);
-}
-EXPORT_SYMBOL_GPL(rust_helper_IS_ERR);
-
-long rust_helper_PTR_ERR(__force const void *ptr)
-{
-	return PTR_ERR(ptr);
-}
-EXPORT_SYMBOL_GPL(rust_helper_PTR_ERR);
-
-const char *rust_helper_errname(int err)
-{
-	return errname(err);
-}
-EXPORT_SYMBOL_GPL(rust_helper_errname);
-
-struct task_struct *rust_helper_get_current(void)
-{
-	return current;
-}
-EXPORT_SYMBOL_GPL(rust_helper_get_current);
-
-void rust_helper_get_task_struct(struct task_struct *t)
-{
-	get_task_struct(t);
-}
-EXPORT_SYMBOL_GPL(rust_helper_get_task_struct);
-
-void rust_helper_put_task_struct(struct task_struct *t)
-{
-	put_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_init_work_with_key(struct work_struct *work, work_func_t func,
-				    bool onstack, const char *name,
-				    struct lock_class_key *key)
-{
-	__init_work(work, onstack);
-	work->data = (atomic_long_t)WORK_DATA_INIT();
-	lockdep_init_map(&work->lockdep_map, name, key, 0);
-	INIT_LIST_HEAD(&work->entry);
-	work->func = func;
-}
-EXPORT_SYMBOL_GPL(rust_helper_init_work_with_key);
-
-void * __must_check __realloc_size(2)
-rust_helper_krealloc(const void *objp, size_t new_size, gfp_t flags)
-{
-	return krealloc(objp, new_size, flags);
-}
-EXPORT_SYMBOL_GPL(rust_helper_krealloc);
-
-/*
- * `bindgen` binds 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 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 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`).
- */
-static_assert(
-	sizeof(size_t) == sizeof(uintptr_t) &&
-	__alignof__(size_t) == __alignof__(uintptr_t),
-	"Rust code expects C `size_t` to match Rust `usize`"
-);
-
-// This will soon be moved to a separate file, so no need to merge with above.
-#include <linux/blk-mq.h>
-#include <linux/blkdev.h>
-
-void *rust_helper_blk_mq_rq_to_pdu(struct request *rq)
-{
-	return blk_mq_rq_to_pdu(rq);
-}
-EXPORT_SYMBOL_GPL(rust_helper_blk_mq_rq_to_pdu);
-
-struct request *rust_helper_blk_mq_rq_from_pdu(void *pdu)
-{
-	return blk_mq_rq_from_pdu(pdu);
-}
-EXPORT_SYMBOL_GPL(rust_helper_blk_mq_rq_from_pdu);
diff --git a/rust/helpers/blk.c b/rust/helpers/blk.c
new file mode 100644
index 000000000000..cc9f4e6a2d23
--- /dev/null
+++ b/rust/helpers/blk.c
@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/blk-mq.h>
+#include <linux/blkdev.h>
+
+void *rust_helper_blk_mq_rq_to_pdu(struct request *rq)
+{
+	return blk_mq_rq_to_pdu(rq);
+}
+
+struct request *rust_helper_blk_mq_rq_from_pdu(void *pdu)
+{
+	return blk_mq_rq_from_pdu(pdu);
+}
diff --git a/rust/helpers/bug.c b/rust/helpers/bug.c
new file mode 100644
index 000000000000..e2d13babc737
--- /dev/null
+++ b/rust/helpers/bug.c
@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/bug.h>
+
+__noreturn void rust_helper_BUG(void)
+{
+	BUG();
+}
diff --git a/rust/helpers/build_assert.c b/rust/helpers/build_assert.c
new file mode 100644
index 000000000000..6a54b2680b14
--- /dev/null
+++ b/rust/helpers/build_assert.c
@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/build_bug.h>
+
+/*
+ * `bindgen` binds 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 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 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`).
+ */
+static_assert(
+	sizeof(size_t) == sizeof(uintptr_t) &&
+	__alignof__(size_t) == __alignof__(uintptr_t),
+	"Rust code expects C `size_t` to match Rust `usize`"
+);
diff --git a/rust/helpers/build_bug.c b/rust/helpers/build_bug.c
new file mode 100644
index 000000000000..e994f7b5928c
--- /dev/null
+++ b/rust/helpers/build_bug.c
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/export.h>
+#include <linux/errname.h>
+
+const char *rust_helper_errname(int err)
+{
+	return errname(err);
+}
diff --git a/rust/helpers/err.c b/rust/helpers/err.c
new file mode 100644
index 000000000000..be3d45ef78a2
--- /dev/null
+++ b/rust/helpers/err.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/err.h>
+#include <linux/export.h>
+
+__force void *rust_helper_ERR_PTR(long err)
+{
+	return ERR_PTR(err);
+}
+
+bool rust_helper_IS_ERR(__force const void *ptr)
+{
+	return IS_ERR(ptr);
+}
+
+long rust_helper_PTR_ERR(__force const void *ptr)
+{
+	return PTR_ERR(ptr);
+}
diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
new file mode 100644
index 000000000000..30f40149f3a9
--- /dev/null
+++ b/rust/helpers/helpers.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Non-trivial C macros cannot be used in Rust. Similarly, inlined C functions
+ * cannot be called either. This file explicitly creates functions ("helpers")
+ * that wrap those so that they can be called from Rust.
+ *
+ * Sorted alphabetically.
+ */
+
+#include "blk.c"
+#include "bug.c"
+#include "build_assert.c"
+#include "build_bug.c"
+#include "err.c"
+#include "kunit.c"
+#include "mutex.c"
+#include "page.c"
+#include "rbtree.c"
+#include "refcount.c"
+#include "signal.c"
+#include "slab.c"
+#include "spinlock.c"
+#include "task.c"
+#include "uaccess.c"
+#include "wait.c"
+#include "workqueue.c"
diff --git a/rust/helpers/kunit.c b/rust/helpers/kunit.c
new file mode 100644
index 000000000000..9d725067eb3b
--- /dev/null
+++ b/rust/helpers/kunit.c
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <kunit/test-bug.h>
+#include <linux/export.h>
+
+struct kunit *rust_helper_kunit_get_current_test(void)
+{
+	return kunit_get_current_test();
+}
diff --git a/rust/helpers/mutex.c b/rust/helpers/mutex.c
new file mode 100644
index 000000000000..200db7e6279f
--- /dev/null
+++ b/rust/helpers/mutex.c
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/export.h>
+#include <linux/mutex.h>
+
+void rust_helper_mutex_lock(struct mutex *lock)
+{
+	mutex_lock(lock);
+}
diff --git a/rust/helpers/page.c b/rust/helpers/page.c
new file mode 100644
index 000000000000..b3f2b8fbf87f
--- /dev/null
+++ b/rust/helpers/page.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/gfp.h>
+#include <linux/highmem.h>
+
+struct page *rust_helper_alloc_pages(gfp_t gfp_mask, unsigned int order)
+{
+	return alloc_pages(gfp_mask, order);
+}
+
+void *rust_helper_kmap_local_page(struct page *page)
+{
+	return kmap_local_page(page);
+}
+
+void rust_helper_kunmap_local(const void *addr)
+{
+	kunmap_local(addr);
+}
diff --git a/rust/helpers/rbtree.c b/rust/helpers/rbtree.c
new file mode 100644
index 000000000000..6d404b84a9b5
--- /dev/null
+++ b/rust/helpers/rbtree.c
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/rbtree.h>
+
+void rust_helper_rb_link_node(struct rb_node *node, struct rb_node *parent,
+			      struct rb_node **rb_link)
+{
+	rb_link_node(node, parent, rb_link);
+}
diff --git a/rust/helpers/refcount.c b/rust/helpers/refcount.c
new file mode 100644
index 000000000000..f47afc148ec3
--- /dev/null
+++ b/rust/helpers/refcount.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/export.h>
+#include <linux/refcount.h>
+
+refcount_t rust_helper_REFCOUNT_INIT(int n)
+{
+	return (refcount_t)REFCOUNT_INIT(n);
+}
+
+void rust_helper_refcount_inc(refcount_t *r)
+{
+	refcount_inc(r);
+}
+
+bool rust_helper_refcount_dec_and_test(refcount_t *r)
+{
+	return refcount_dec_and_test(r);
+}
diff --git a/rust/help