[PATCH v3 6/6] rust: use strict provenance APIs

Tamir Duberstein
2025-03-14T12:28:28Z

Rust 1.84.0 stabilized the strict provenance APIs[1].

This patch enables the (unstable) lints `fuzzy_provenance_casts` and
`lossy_provenance_casts` (available since Rust 1.61.0[2]) and uses
strict provenance APIs where these lints triggered. The `kernel` crate
is kept backwards-compatible by introducing forwarding functions at the
root which are marked `#[allow(clippy::incompatible_msrv)]` to avoid
warnings on rustc < 1.84.0.

The discussion in the tracking Issue for strict_provenance_lints[3]
seems to be nearing resolution with the only open question being:

> do we really want two separate lints for the two directions?

which seems minor enough that this is unlikely to cause significant
churn when stabilized.

This is limited to the `kernel` crate because adding these lints in the
root `Makefile` causes `core` itself to be compiled with them, which in
turn causes warnings on the implementations of the strict provenance
APIs themselves.

Link: https://blog.rust-lang.org/2025/01/09/Rust-1.84.0.html#strict-provenance-apis [1]
Link: https://github.com/rust-lang/rust/blob/e71f9a9a98b0faf423844bf0ba7438f29dc27d58/compiler/rustc_feature/src/unstable.rs#L605 [2]
Link: https://github.com/rust-lang/rust/issues/130351 [3]
Suggested-by: Benno Lossin <benno.lossin@proton.me>
Link: https://lore.kernel.org/all/D8EIXDMRXMJP.36TFCGWZBRS3Y@proton.me/
---
Makefile | 9 ++++++++-
init/Kconfig | 3 +++
rust/Makefile | 26 ++++++++++++++++++++------
rust/kernel/alloc.rs | 2 +-
rust/kernel/devres.rs | 4 ++--
rust/kernel/io.rs | 14 +++++++-------
rust/kernel/lib.rs | 20 ++++++++++++++++++++
rust/kernel/of.rs | 2 +-
rust/kernel/pci.rs | 4 ++--
rust/kernel/str.rs | 16 ++++++----------
rust/kernel/uaccess.rs | 12 ++++++++----
scripts/Makefile.build | 2 +-
scripts/Makefile.host | 4 ++++
13 files changed, 83 insertions(+), 35 deletions(-)

diff --git a/Makefile b/Makefile
index 2af40bfed9ce..bc12650783f1 100644
--- a/Makefile
+++ b/Makefile
@@ -473,6 +473,8 @@ export rust_common_flags := --edition=2021 \
-Astable_features \
-Dnon_ascii_idents \
-Dunsafe_op_in_unsafe_fn \
+ -Wfuzzy_provenance_casts \
+ -Wlossy_provenance_casts \
-Wmissing_docs \
-Wrust_2018_idioms \
-Wunreachable_pub \
@@ -498,7 +500,7 @@ KBUILD_HOSTCFLAGS := $(KBUILD_USERHOSTCFLAGS) $(HOST_LFS_CFLAGS) \
KBUILD_HOSTCXXFLAGS := -Wall -O2 $(HOST_LFS_CFLAGS) $(HOSTCXXFLAGS) \
-I $(srctree)/scripts/include
KBUILD_HOSTRUSTFLAGS := $(rust_common_flags) -O -Cstrip=debuginfo \
- -Zallow-features= $(HOSTRUSTFLAGS)
+ $(HOSTRUSTFLAGS)
KBUILD_HOSTLDFLAGS := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS)
KBUILD_HOSTLDLIBS := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
KBUILD_PROCMACROLDFLAGS := $(or $(PROCMACROLDFLAGS),$(KBUILD_HOSTLDFLAGS))
@@ -870,6 +872,11 @@ KBUILD_CFLAGS += -Os
KBUILD_RUSTFLAGS += -Copt-level=s
endif

+# Lints were moved to `strict_provenance_lints` when `strict_provenance` was stabilized.
+#
+# See https://github.com/rust-lang/rust/commit/56ee492a6e7a917b2b3f888e33dd52a13d3ecb64.
+export rustc_strict_provenance_feature := $(if $(CONFIG_RUSTC_HAS_STABLE_STRICT_PROVENANCE),strict_provenance_lints,strict_provenance)
+
# Always set `debug-assertions` and `overflow-checks` because their default
# depends on `opt-level` and `debug-assertions`, respectively.
KBUILD_RUSTFLAGS += -Cdebug-assertions=$(if $(CONFIG_RUST_DEBUG_ASSERTIONS),y,n)
diff --git a/init/Kconfig b/init/Kconfig
index 324c2886b2ea..04df2893348c 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -132,6 +132,9 @@ config CC_HAS_COUNTED_BY
config RUSTC_HAS_COERCE_POINTEE
def_bool RUSTC_VERSION >= 108400

+config RUSTC_HAS_STABLE_STRICT_PROVENANCE
+ def_bool RUSTC_VERSION >= 108400
+
config PAHOLE_VERSION
int
default $(shell,$(srctree)/scripts/pahole-version.sh $(PAHOLE))
diff --git a/rust/Makefile b/rust/Makefile
index ea3849eb78f6..dad47bea19f3 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -57,10 +57,12 @@ endif
core-cfgs = \
--cfg no_fp_fmt_parse

+rustc_strict_provenance_flags = -Zcrate-attr='feature($(rustc_strict_provenance_feature))'
+
quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
cmd_rustdoc = \
OBJTREE=$(abspath $(objtree)) \
- $(RUSTDOC) $(filter-out $(skip_flags),$(if $(rustdoc_host),$(rust_common_flags),$(rust_flags))) \
+ $(RUSTDOC) $(filter-out $(skip_flags),$(if $(rustdoc_host),$(rust_common_flags),$(rust_flags)) $(rustc_strict_provenance_flags)) \
$(rustc_target_flags) -L$(objtree)/$(obj) \
-Zunstable-options --generate-link-to-definition \
--output $(rustdoc_output) \
@@ -99,7 +101,7 @@ rustdoc-macros: $(src)/macros/lib.rs FORCE

# 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 = -Wrustdoc::unescaped_backticks
+rustdoc-core: private skip_flags = -Wrustdoc::unescaped_backticks $(rustc_strict_provenance_flags)
rustdoc-core: private rustc_target_flags = $(core-cfgs)
rustdoc-core: $(RUST_LIB_SRC)/core/src/lib.rs FORCE
+$(call if_changed,rustdoc)
@@ -122,6 +124,7 @@ quiet_cmd_rustc_test_library = $(RUSTC_OR_CLIPPY_QUIET) TL $<
cmd_rustc_test_library = \
OBJTREE=$(abspath $(objtree)) \
$(RUSTC_OR_CLIPPY) $(rust_common_flags) \
+ $(rustc_strict_provenance_flags) \
@$(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 \
@@ -155,11 +158,19 @@ rusttestlib-uapi: private rustc_target_flags = --extern ffi
rusttestlib-uapi: $(src)/uapi/lib.rs rusttestlib-ffi FORCE
+$(call if_changed,rustc_test_library)

+# `rustdoc --test` doesn't respect `-Zcrate-attr`, which means we can't use
+# `rustc_strict_provenance_flags` below. Instead we filter out those lints to avoid unknown lint
+# warnings.
+#
+# See https://github.com/rust-lang/rust/issues/138491.
+rustc_strict_provenance_lints = -Wfuzzy_provenance_casts -Wlossy_provenance_casts
+
quiet_cmd_rustdoc_test = RUSTDOC T $<
cmd_rustdoc_test = \
RUST_MODFILE=test.rs \
OBJTREE=$(abspath $(objtree)) \
- $(RUSTDOC) --test $(rust_common_flags) \
+ $(RUSTDOC) --test \
+ $(filter-out $(rustc_strict_provenance_lints),$(rust_common_flags)) \
@$(objtree)/include/generated/rustc_cfg \
$(rustc_target_flags) $(rustdoc_test_target_flags) \
$(rustdoc_test_quiet) \
@@ -171,7 +182,8 @@ quiet_cmd_rustdoc_test_kernel = RUSTDOC TK $<
rm -rf $(objtree)/$(obj)/test/doctests/kernel; \
mkdir -p $(objtree)/$(obj)/test/doctests/kernel; \
OBJTREE=$(abspath $(objtree)) \
- $(RUSTDOC) --test $(rust_flags) \
+ $(RUSTDOC) --test \
+ $(filter-out $(rustc_strict_provenance_lints),$(rust_flags)) \
-L$(objtree)/$(obj) --extern ffi --extern kernel \
--extern build_error --extern macros \
--extern bindings --extern uapi \
@@ -193,6 +205,7 @@ quiet_cmd_rustc_test = $(RUSTC_OR_CLIPPY_QUIET) T $<
cmd_rustc_test = \
OBJTREE=$(abspath $(objtree)) \
$(RUSTC_OR_CLIPPY) --test $(rust_common_flags) \
+ $(rustc_strict_provenance_flags) \
@$(objtree)/include/generated/rustc_cfg \
$(rustc_target_flags) --out-dir $(objtree)/$(obj)/test \
-L$(objtree)/$(obj)/test \
@@ -362,6 +375,7 @@ $(obj)/exports_kernel_generated.h: $(obj)/kernel.o FORCE
quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
cmd_rustc_procmacro = \
$(RUSTC_OR_CLIPPY) $(rust_common_flags) \
+ $(rustc_strict_provenance_flags) \
-Clinker-flavor=gcc -Clinker=$(HOSTCC) \
-Clink-args='$(call escsq,$(KBUILD_PROCMACROLDFLAGS))' \
--emit=dep-info=$(depfile) --emit=link=$@ --extern proc_macro \
@@ -376,7 +390,7 @@ 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)) \
+ $(filter-out $(skip_flags),$(rust_flags) $(rustc_target_flags) $(rustc_strict_provenance_flags)) \
--emit=dep-info=$(depfile) --emit=obj=$@ \
--emit=metadata=$(dir $@)$(patsubst %.o,lib%.rmeta,$(notdir $@)) \
--crate-type rlib -L$(objtree)/$(obj) \
@@ -436,7 +450,7 @@ $(obj)/helpers/helpers.o: $(src)/helpers/helpers.c $(recordmcount_source) FORCE
$(obj)/exports.o: private skip_gendwarfksyms = 1

$(obj)/core.o: private skip_clippy = 1
-$(obj)/core.o: private skip_flags = -Wunreachable_pub
+$(obj)/core.o: private skip_flags = -Wunreachable_pub -Wlossy_provenance_casts $(rustc_strict_provenance_flags)
$(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 \
diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
index fc9c9c41cd79..59199a6da2ed 100644
--- a/rust/kernel/alloc.rs
+++ b/rust/kernel/alloc.rs
@@ -217,7 +217,7 @@ unsafe fn free(ptr: NonNull<u8>, layout: Layout) {

/// Returns a properly aligned dangling pointer from the given `layout`.
pub(crate) fn dangling_from_layout(layout: Layout) -> NonNull<u8> {
- let ptr = layout.align() as *mut u8;
+ let ptr = crate::with_exposed_provenance_mut(layout.align());

// SAFETY: `layout.align()` (and hence `ptr`) is guaranteed to be non-zero.
unsafe { NonNull::new_unchecked(ptr) }
diff --git a/rust/kernel/devres.rs b/rust/kernel/devres.rs
index 34571f992f0d..e8232bb771b2 100644
--- a/rust/kernel/devres.rs
+++ b/rust/kernel/devres.rs
@@ -64,14 +64,14 @@ struct DevresInner<T> {
/// return Err(ENOMEM);
/// }
///
-/// Ok(IoMem(IoRaw::new(addr as usize, SIZE)?))
+/// Ok(IoMem(IoRaw::new(kernel::expose_provenance(addr), SIZE)?))
/// }
/// }
///
/// impl<const SIZE: usize> Drop for IoMem<SIZE> {
/// fn drop(&mut self) {
/// // SAFETY: `self.0.addr()` is guaranteed to be properly mapped by `Self::new`.
-/// unsafe { bindings::iounmap(self.0.addr() as *mut c_void); };
+/// unsafe { bindings::iounmap(kernel::with_exposed_provenance_mut(self.0.addr())); };
/// }
/// }
///
diff --git a/rust/kernel/io.rs b/rust/kernel/io.rs
index 9d2aadf40edf..0a018ad7478a 100644
--- a/rust/kernel/io.rs
+++ b/rust/kernel/io.rs
@@ -5,7 +5,7 @@
//! C header: [`include/asm-generic/io.h`](srctree/include/asm-generic/io.h)

use crate::error::{code::EINVAL, Result};
-use crate::{bindings, build_assert, ffi::c_void};
+use crate::{bindings, build_assert};

/// Raw representation of an MMIO region.
///
@@ -75,14 +75,14 @@ pub fn maxsize(&self) -> usize {
/// return Err(ENOMEM);
/// }
///
-/// Ok(IoMem(IoRaw::new(addr as usize, SIZE)?))
+/// Ok(IoMem(IoRaw::new(kernel::expose_provenance(addr), SIZE)?))
/// }
/// }
///
/// impl<const SIZE: usize> Drop for IoMem<SIZE> {
/// fn drop(&mut self) {
/// // SAFETY: `self.0.addr()` is guaranteed to be properly mapped by `Self::new`.
-/// unsafe { bindings::iounmap(self.0.addr() as *mut c_void); };
+/// unsafe { bindings::iounmap(kernel::with_exposed_provenance_mut(self.0.addr())); };
/// }
/// }
///
@@ -119,7 +119,7 @@ pub fn $name(&self, offset: usize) -> $type_name {
let addr = self.io_addr_assert::<$type_name>(offset);

// SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
- unsafe { bindings::$name(addr as *const c_void) }
+ unsafe { bindings::$name(crate::with_exposed_provenance(addr)) }
}

/// Read IO data from a given offset.
@@ -131,7 +131,7 @@ pub fn $try_name(&self, offset: usize) -> Result<$type_name> {
let addr = self.io_addr::<$type_name>(offset)?;

// SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
- Ok(unsafe { bindings::$name(addr as *const c_void) })
+ Ok(unsafe { bindings::$name(crate::with_exposed_provenance(addr)) })
}
};
}
@@ -148,7 +148,7 @@ pub fn $name(&self, value: $type_name, offset: usize) {
let addr = self.io_addr_assert::<$type_name>(offset);

// SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
- unsafe { bindings::$name(value, addr as *mut c_void) }
+ unsafe { bindings::$name(value, crate::with_exposed_provenance_mut(addr)) }
}

/// Write IO data from a given offset.
@@ -160,7 +160,7 @@ pub fn $try_name(&self, value: $type_name, offset: usize) -> Result {
let addr = self.io_addr::<$type_name>(offset)?;

// SAFETY: By the type invariant `addr` is a valid address for MMIO operations.
- unsafe { bindings::$name(value, addr as *mut c_void) }
+ unsafe { bindings::$name(value, crate::with_exposed_provenance_mut(addr)) }
Ok(())
}
};
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 9cd6b6864739..ebf7db3ad9ee 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -25,6 +25,26 @@
#![feature(const_ptr_write)]
#![feature(const_refs_to_cell)]

+#[allow(clippy::incompatible_msrv)]
+mod strict_provenance {
+ #[doc(hidden)]
+ pub fn expose_provenance<T>(addr: *const T) -> usize {
+ addr.expose_provenance()
+ }
+
+ #[doc(hidden)]
+ pub fn with_exposed_provenance<T>(addr: usize) -> *const T {
+ core::ptr::with_exposed_provenance(addr)
+ }
+
+ #[doc(hidden)]
+ pub fn with_exposed_provenance_mut<T>(addr: usize) -> *mut T {
+ core::ptr::with_exposed_provenance_mut(addr)
+ }
+}
+
+pub use strict_provenance::*;
+
// Ensure conditional compilation based on the kernel configuration works;
// otherwise we may silently break things like initcall handling.
#[cfg(not(CONFIG_RUST))]
diff --git a/rust/kernel/of.rs b/rust/kernel/of.rs
index 40d1bd13682c..f9459694cbdc 100644
--- a/rust/kernel/of.rs
+++ b/rust/kernel/of.rs
@@ -22,7 +22,7 @@ unsafe impl RawDeviceId for DeviceId {
const DRIVER_DATA_OFFSET: usize = core::mem::offset_of!(bindings::of_device_id, data);

fn index(&self) -> usize {
- self.0.data as usize
+ crate::expose_provenance(self.0.data)
}
}

diff --git a/rust/kernel/pci.rs b/rust/kernel/pci.rs
index a925732f6c7a..bb38d83e2608 100644
--- a/rust/kernel/pci.rs
+++ b/rust/kernel/pci.rs
@@ -287,7 +287,7 @@ fn new(pdev: Device, num: u32, name: &CStr) -> Result<Self> {
// `pdev` is valid by the invariants of `Device`.
// `num` is checked for validity by a previous call to `Device::resource_len`.
// `name` is always valid.
- let ioptr: usize = unsafe { bindings::pci_iomap(pdev.as_raw(), num, 0) } as usize;
+ let ioptr = crate::expose_provenance(unsafe { bindings::pci_iomap(pdev.as_raw(), num, 0) });
if ioptr == 0 {
// SAFETY:
// `pdev` valid by the invariants of `Device`.
@@ -320,7 +320,7 @@ unsafe fn do_release(pdev: &Device, ioptr: usize, num: i32) {
// `ioptr` is valid by the safety requirements.
// `num` is valid by the safety requirements.
unsafe {
- bindings::pci_iounmap(pdev.as_raw(), ioptr as *mut kernel::ffi::c_void);
+ bindings::pci_iounmap(pdev.as_raw(), crate::with_exposed_provenance_mut(ioptr));
bindings::pci_release_region(pdev.as_raw(), num);
}
}
diff --git a/rust/kernel/str.rs b/rust/kernel/str.rs
index 0b80a119d5f0..6bc6357293e4 100644
--- a/rust/kernel/str.rs
+++ b/rust/kernel/str.rs
@@ -692,9 +692,9 @@ fn new() -> Self {
pub(crate) unsafe fn from_ptrs(pos: *mut u8, end: *mut u8) -> Self {
// INVARIANT: The safety requirements guarantee the type invariants.
Self {
- beg: pos as usize,
- pos: pos as usize,
- end: end as usize,
+ beg: crate::expose_provenance(pos),
+ pos: crate::expose_provenance(pos),
+ end: crate::expose_provenance(end),
}
}

@@ -705,7 +705,7 @@ pub(crate) unsafe fn from_ptrs(pos: *mut u8, end: *mut u8) -> Self {
/// The memory region starting at `buf` and extending for `len` bytes must be valid for writes
/// for the lifetime of the returned [`RawFormatter`].
pub(crate) unsafe fn from_buffer(buf: *mut u8, len: usize) -> Self {
- let pos = buf as usize;
+ let pos = crate::expose_provenance(buf);
// INVARIANT: We ensure that `end` is never less then `buf`, and the safety requirements
// guarantees that the memory region is valid for writes.
Self {
@@ -719,7 +719,7 @@ pub(crate) unsafe fn from_buffer(buf: *mut u8, len: usize) -> Self {
///
/// N.B. It may point to invalid memory.
pub(crate) fn pos(&self) -> *mut u8 {
- self.pos as *mut u8
+ crate::with_exposed_provenance_mut(self.pos)
}

/// Returns the number of bytes written to the formatter.
@@ -741,11 +741,7 @@ fn write_str(&mut self, s: &str) -> fmt::Result {
// SAFETY: If `len_to_copy` is non-zero, then we know `pos` has not gone past `end`
// yet, so it is valid for write per the type invariants.
unsafe {
- core::ptr::copy_nonoverlapping(
- s.as_bytes().as_ptr(),
- self.pos as *mut u8,
- len_to_copy,
- )
+ core::ptr::copy_nonoverlapping(s.as_bytes().as_ptr(), self.pos(), len_to_copy)
};
}

diff --git a/rust/kernel/uaccess.rs b/rust/kernel/uaccess.rs
index 719b0a48ff55..96393bcf6bd7 100644
--- a/rust/kernel/uaccess.rs
+++ b/rust/kernel/uaccess.rs
@@ -226,7 +226,9 @@ pub fn read_raw(&mut self, out: &mut [MaybeUninit<u8>]) -> Result {
}
// SAFETY: `out_ptr` points into a mutable slice of length `len`, so we may write
// that many bytes to it.
- let res = unsafe { bindings::copy_from_user(out_ptr, self.ptr as *const c_void, len) };
+ let res = unsafe {
+ bindings::copy_from_user(out_ptr, crate::with_exposed_provenance(self.ptr), len)
+ };
if res != 0 {
return Err(EFAULT);
}
@@ -264,7 +266,7 @@ pub fn read<T: FromBytes>(&mut self) -> Result<T> {
let res = unsafe {
bindings::_copy_from_user(
out.as_mut_ptr().cast::<c_void>(),
- self.ptr as *const c_void,
+ crate::with_exposed_provenance(self.ptr),
len,
)
};
@@ -330,7 +332,9 @@ pub fn write_slice(&mut self, data: &[u8]) -> Result {
}
// SAFETY: `data_ptr` points into an immutable slice of length `len`, so we may read
// that many bytes from it.
- let res = unsafe { bindings::copy_to_user(self.ptr as *mut c_void, data_ptr, len) };
+ let res = unsafe {
+ bindings::copy_to_user(crate::with_exposed_provenance_mut(self.ptr), data_ptr, len)
+ };
if res != 0 {
return Err(EFAULT);
}
@@ -357,7 +361,7 @@ pub fn write<T: AsBytes>(&mut self, value: &T) -> Result {
// is a compile-time constant.
let res = unsafe {
bindings::_copy_to_user(
- self.ptr as *mut c_void,
+ crate::with_exposed_provenance_mut(self.ptr),
(value as *const T).cast::<c_void>(),
len,
)
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 993708d11874..34575f3be0fc 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -226,7 +226,7 @@ $(obj)/%.lst: $(obj)/%.c FORCE
# Compile Rust sources (.rs)
# ---------------------------------------------------------------------------

-rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons
+rust_allowed_features := asm_const,asm_goto,arbitrary_self_types,lint_reasons,$(rustc_strict_provenance_feature)

# `--out-dir` is required to avoid temporaries being created by `rustc` in the
# current working directory, which may be not accessible in the out-of-tree
diff --git a/scripts/Makefile.host b/scripts/Makefile.host
index c1dedf646a39..7e2f35bff59c 100644
--- a/scripts/Makefile.host
+++ b/scripts/Makefile.host
@@ -87,10 +87,14 @@ hostcxx_flags = -Wp,-MMD,$(depfile) \
$(KBUILD_HOSTCXXFLAGS) $(HOST_EXTRACXXFLAGS) \
$(HOSTCXXFLAGS_$(target-stem).o)

+rust_allowed_features := $(rustc_strict_provenance_feature)
+
# `--out-dir` is required to avoid temporaries being created by `rustc` in the
# current working directory, which may be not accessible in the out-of-tree
# modules case.
hostrust_flags = --out-dir $(dir $@) --emit=dep-info=$(depfile) \
+ -Zallow-features=$(rust_allowed_features) \
+ -Zcrate-attr='feature($(rust_allowed_features))' \
-Clinker-flavor=gcc -Clinker=$(HOSTCC) \
-Clink-args='$(call escsq,$(KBUILD_HOSTLDFLAGS))' \
$(KBUILD_HOSTRUSTFLAGS) $(HOST_EXTRARUSTFLAGS) \

--
2.48.1