Merge patch series "rust: bump minimum Rust and bindgen versions"

As proposed in the past in e.g. LPC 2025 and the Maintainers Summit [1],
we are going to follow Debian Stable's Rust versions as our minimum
supported version.

Debian Trixie was released with a Rust 1.85.0 toolchain [2], which it
still uses to this day [3] (i.e. no update to Rust 1.85.1).

Debian Trixie was released with `bindgen` 0.71.1, which it also still
uses to this day [4].

Debian Trixie's release happened on 2025-08-09 [5], which means that a
fair amount of time has passed since its release for kernel developers
to upgrade.

Thus bump the minimum to the new versions, i.e.

  - Rust: 1.78.0 -> 1.85.0
  - bindgen: 0.65.1 -> 0.71.1

There are a few main parts to the series, in this order:

  - A few cleanups that can be performed before the bumps.
  - The Rust bump (and its cleanups).
  - The `bindgen` bump (and its cleanups).
  - Documentation updates.
  - The `cfi_encoding` patch, added here, which needs the bump.
  - The per-version flags support and a Clippy cleanup on top.

Link: https://lwn.net/Articles/1050174/ [1]
Link: https://www.debian.org/releases/trixie/release-notes/whats-new.en.html#desktops-and-well-known-packages [2]
Link: https://packages.debian.org/trixie/rustc [3]
Link: https://packages.debian.org/trixie/bindgen [4]
Link: https://www.debian.org/releases/trixie/ [5]
Link: https://patch.msgid.link/20260405235309.418950-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: ojeda

.clippy.toml

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-msrv = "1.78.0"
+msrv = "1.85.0"
 
 check-private-items = true
 

Documentation/process/changes.rst

@@ -31,8 +31,8 @@ you probably needn't concern yourself with pcmciautils.
 ====================== ===============  ========================================
 GNU C                  8.1              gcc --version
 Clang/LLVM (optional)  15.0.0           clang --version
-Rust (optional)        1.78.0           rustc --version
-bindgen (optional)     0.65.1           bindgen --version
+Rust (optional)        1.85.0           rustc --version
+bindgen (optional)     0.71.1           bindgen --version
 GNU make               4.0              make --version
 bash                   4.2              bash --version
 binutils               2.30             ld -v

Documentation/rust/general-information.rst

@@ -157,5 +157,5 @@ numerical comparisons, one may define a new Kconfig symbol:
 
 .. code-block:: kconfig
 
-	config RUSTC_VERSION_MIN_107900
-		def_bool y if RUSTC_VERSION >= 107900
+	config RUSTC_HAS_SPAN_FILE
+		def_bool RUSTC_VERSION >= 108800

Documentation/rust/quick-start.rst

@@ -57,8 +57,8 @@ of the box, e.g.::
 Gentoo Linux
 ************
 
-Gentoo Linux (and especially the testing branch) provides recent Rust releases
-and thus it should generally work out of the box, e.g.::
+Gentoo Linux provides recent Rust releases and thus it should generally work out
+of the box, e.g.::
 
 	USE='rust-src rustfmt clippy' emerge dev-lang/rust dev-util/bindgen
 
@@ -68,8 +68,8 @@ and thus it should generally work out of the box, e.g.::
 Nix
 ***
 
-Nix (unstable channel) provides recent Rust releases and thus it should
-generally work out of the box, e.g.::
+Nix provides recent Rust releases and thus it should generally work out of the
+box, e.g.::
 
 	{ pkgs ? import <nixpkgs> {} }:
 	pkgs.mkShell {
@@ -84,16 +84,13 @@ openSUSE
 openSUSE Slowroll and openSUSE Tumbleweed provide recent Rust releases and thus
 they should generally work out of the box, e.g.::
 
-	zypper install rust rust1.79-src rust-bindgen clang
+	zypper install rust rust-src rust-bindgen clang
 
 
 Ubuntu
 ******
 
-25.04
-~~~~~
-
-The latest Ubuntu releases provide recent Rust releases and thus they should
+Ubuntu 25.10 and 26.04 LTS provide recent Rust releases and thus they should
 generally work out of the box, e.g.::
 
 	apt install rustc rust-src bindgen rustfmt rust-clippy
@@ -112,33 +109,33 @@ Though Ubuntu 24.04 LTS and older versions still provide recent Rust
 releases, they require some additional configuration to be set, using
 the versioned packages, e.g.::
 
-	apt install rustc-1.80 rust-1.80-src bindgen-0.65 rustfmt-1.80 \
-		rust-1.80-clippy
-	ln -s /usr/lib/rust-1.80/bin/rustfmt /usr/bin/rustfmt-1.80
-	ln -s /usr/lib/rust-1.80/bin/clippy-driver /usr/bin/clippy-driver-1.80
+	apt install rustc-1.85 rust-1.85-src bindgen-0.71 rustfmt-1.85 \
+		rust-1.85-clippy
+	ln -s /usr/lib/rust-1.85/bin/rustfmt /usr/bin/rustfmt-1.85
+	ln -s /usr/lib/rust-1.85/bin/clippy-driver /usr/bin/clippy-driver-1.85
 
 None of these packages set their tools as defaults; therefore they should be
 specified explicitly, e.g.::
 
-	make LLVM=1 RUSTC=rustc-1.80 RUSTDOC=rustdoc-1.80 RUSTFMT=rustfmt-1.80 \
-		CLIPPY_DRIVER=clippy-driver-1.80 BINDGEN=bindgen-0.65
+	make LLVM=1 RUSTC=rustc-1.85 RUSTDOC=rustdoc-1.85 RUSTFMT=rustfmt-1.85 \
+		CLIPPY_DRIVER=clippy-driver-1.85 BINDGEN=bindgen-0.71
 
-Alternatively, modify the ``PATH`` variable to place the Rust 1.80 binaries
+Alternatively, modify the ``PATH`` variable to place the Rust 1.85 binaries
 first and set ``bindgen`` as the default, e.g.::
 
-	PATH=/usr/lib/rust-1.80/bin:$PATH
+	PATH=/usr/lib/rust-1.85/bin:$PATH
 	update-alternatives --install /usr/bin/bindgen bindgen \
-		/usr/bin/bindgen-0.65 100
-	update-alternatives --set bindgen /usr/bin/bindgen-0.65
+		/usr/bin/bindgen-0.71 100
+	update-alternatives --set bindgen /usr/bin/bindgen-0.71
 
-``RUST_LIB_SRC`` needs to be set when using the versioned packages, e.g.::
+``RUST_LIB_SRC`` may need to be set when using the versioned packages, e.g.::
 
-	RUST_LIB_SRC=/usr/src/rustc-$(rustc-1.80 --version | cut -d' ' -f2)/library
+	RUST_LIB_SRC=/usr/src/rustc-$(rustc-1.85 --version | cut -d' ' -f2)/library
 
 For convenience, ``RUST_LIB_SRC`` can be exported to the global environment.
 
-In addition, ``bindgen-0.65`` is available in newer releases (24.04 LTS and
-24.10), but it may not be available in older ones (20.04 LTS and 22.04 LTS),
+In addition, ``bindgen-0.71`` is available in newer releases (24.04 LTS),
+but it may not be available in older ones (20.04 LTS and 22.04 LTS),
 thus ``bindgen`` may need to be built manually (please see below).
 
 
@@ -355,12 +352,3 @@ Hacking
 To dive deeper, take a look at the source code of the samples
 at ``samples/rust/``, the Rust support code under ``rust/`` and
 the ``Rust hacking`` menu under ``Kernel hacking``.
-
-If GDB/Binutils is used and Rust symbols are not getting demangled, the reason
-is the toolchain does not support Rust's new v0 mangling scheme yet.
-There are a few ways out:
-
-- Install a newer release (GDB >= 10.2, Binutils >= 2.36).
-
-- Some versions of GDB (e.g. vanilla GDB 10.1) are able to use
-  the pre-demangled names embedded in the debug info (``CONFIG_DEBUG_INFO``).

Makefile

@@ -486,6 +486,7 @@ export rust_common_flags := --edition=2021 \
 			    -Wclippy::as_underscore \
 			    -Wclippy::cast_lossless \
 			    -Wclippy::ignored_unit_patterns \
+			    -Aclippy::incompatible_msrv \
 			    -Wclippy::mut_mut \
 			    -Wclippy::needless_bitwise_bool \
 			    -Aclippy::needless_lifetimes \
@@ -505,7 +506,7 @@ 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)
+			-Zallow-features=
 KBUILD_HOSTLDFLAGS  := $(HOST_LFS_LDFLAGS) $(HOSTLDFLAGS)
 KBUILD_HOSTLDLIBS   := $(HOST_LFS_LIBS) $(HOSTLDLIBS)
 KBUILD_PROCMACROLDFLAGS := $(or $(PROCMACROLDFLAGS),$(KBUILD_HOSTLDFLAGS))
@@ -835,6 +836,20 @@ endif # CONFIG_TRACEPOINTS
 
 export WARN_ON_UNUSED_TRACEPOINTS
 
+# Per-version Rust flags. These are like `rust_common_flags`, but may
+# depend on the Rust compiler version (e.g. using `rustc-min-version`).
+#
+# `-Aclippy::precedence`: the lint was extended in Rust 1.85.0 to
+# include bitmasking and shift operations. However, because it generated
+# many hits, in Rust 1.86.0 it was split into a new `precedence_bits`
+# lint which is not enabled by default.
+rust_common_flags_per_version := \
+    $(if $(call rustc-min-version,108600),,-Aclippy::precedence)
+
+rust_common_flags += $(rust_common_flags_per_version)
+KBUILD_HOSTRUSTFLAGS += $(rust_common_flags_per_version) $(HOSTRUSTFLAGS)
+KBUILD_RUSTFLAGS += $(rust_common_flags_per_version)
+
 include $(srctree)/arch/$(SRCARCH)/Makefile
 
 ifdef need-config

arch/Kconfig

@@ -968,10 +968,9 @@ config HAVE_CFI_ICALL_NORMALIZE_INTEGERS
 config HAVE_CFI_ICALL_NORMALIZE_INTEGERS_RUSTC
 	def_bool y
 	depends on HAVE_CFI_ICALL_NORMALIZE_INTEGERS
-	depends on RUSTC_VERSION >= 107900
 	depends on ARM64 || X86_64
 	# With GCOV/KASAN we need this fix: https://github.com/rust-lang/rust/pull/129373
-	depends on (RUSTC_LLVM_VERSION >= 190103 && RUSTC_VERSION >= 108200) || \
+	depends on RUSTC_LLVM_VERSION >= 190103 || \
 		(!GCOV_KERNEL && !KASAN_GENERIC && !KASAN_SW_TAGS)
 
 config CFI_PERMISSIVE

arch/arm64/Kconfig

@@ -291,14 +291,6 @@ config ARM64
 config RUSTC_SUPPORTS_ARM64
 	def_bool y
 	depends on CPU_LITTLE_ENDIAN
-	# Shadow call stack is only supported on certain rustc versions.
-	#
-	# When using the UNWIND_PATCH_PAC_INTO_SCS option, rustc version 1.80+ is
-	# required due to use of the -Zfixed-x18 flag.
-	#
-	# Otherwise, rustc version 1.82+ is required due to use of the
-	# -Zsanitizer=shadow-call-stack flag.
-	depends on !SHADOW_CALL_STACK || RUSTC_VERSION >= 108200 || RUSTC_VERSION >= 108000 && UNWIND_PATCH_PAC_INTO_SCS
 
 config CLANG_SUPPORTS_DYNAMIC_FTRACE_WITH_ARGS
 	def_bool CC_IS_CLANG

arch/riscv/Kconfig

@@ -232,9 +232,6 @@ config RISCV
 config RUSTC_SUPPORTS_RISCV
 	def_bool y
 	depends on 64BIT
-	# Shadow call stack requires rustc version 1.82+ due to use of the
-	# -Zsanitizer=shadow-call-stack flag.
-	depends on !SHADOW_CALL_STACK || RUSTC_VERSION >= 108200
 
 config CLANG_SUPPORTS_DYNAMIC_FTRACE
 	def_bool CC_IS_CLANG

drivers/android/binder/Makefile

@@ -5,5 +5,4 @@ obj-$(CONFIG_ANDROID_BINDER_IPC_RUST) += rust_binder.o
 rust_binder-y := \
 	rust_binder_main.o	\
 	rust_binderfs.o		\
-	rust_binder_events.o	\
-	page_range_helper.o
+	rust_binder_events.o

drivers/android/binder/page_range.rs

@@ -642,15 +642,15 @@ unsafe extern "C" fn rust_shrink_scan(
     unsafe {
         bindings::list_lru_walk(
             list_lru,
-            Some(bindings::rust_shrink_free_page_wrap),
+            Some(rust_shrink_free_page),
             ptr::null_mut(),
             nr_to_scan,
         )
     }
 }
 
-const LRU_SKIP: bindings::lru_status = bindings::lru_status_LRU_SKIP;
-const LRU_REMOVED_ENTRY: bindings::lru_status = bindings::lru_status_LRU_REMOVED_RETRY;
+const LRU_SKIP: bindings::lru_status = bindings::lru_status::LRU_SKIP;
+const LRU_REMOVED_ENTRY: bindings::lru_status = bindings::lru_status::LRU_REMOVED_RETRY;
 
 /// # Safety
 /// Called by the shrinker.