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git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
Pull devicetree updates from Rob Herring:
"DT core:
- Add support for handling multiple cells in "iommu-map" entries
- Support only 1 entry in /reserved-memory "reg" entries. Support for
more than 1 entry has been broken
- Fix a UAF on alloc_reserved_mem_array() failure
- Make "ibm,phandle" handling logic specific to PPC
- Use memcpy() instead of strcpy() for known length strings
- Ensure __of_find_n_match_cpu_property() handles malformed "reg"
entries
- Add various checks that expected strings are strings before
accessing them
- Drop redundant memset() when unflattening DT
DT bindings:
- Add a DTS style checker. Currently hooked up to dt_binding_check to
check examples
- Convert st,nomadik platform, ti,omap-dmm, and ti,irq-crossbar
bindings to DT schema
- Add Apple System Management Controller hwmon, Qualcomm Hamoa
Embedded Controller, Qualcomm IPQ6018 PWM controller, fsl,mc1323,
Samsung SOFEF01-M DDIC panel, Freescale i.MX53 Television Encoder,
Samsung S2M series PMIC extcon, and MT6365 PMIC AuxADC schemas
- Extend bindings for QCom Maili and Nord PDC, QCom Hali fastrpc,
qcom,eliza-imem, qcom,oryon-1-5 CPU, and MT6365 Keys
- Consolidate "sram" property definitions
- Fix constraints on "nvmem" properties which only contain phandles
and no arg cells
- Another pass of fixing "phandle-array" constraints
- Add Gira vendor prefix"
* tag 'devicetree-for-7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux: (50 commits)
dt-bindings: interrupt-controller: qcom,pdc: Add Maili compatible string
dt-bindings: interrupt-controller: ti,irq-crossbar: Convert to DT schema
dt-bindings: vendor-prefixes: add Gira
dt-bindings: embedded-controller: Add Qualcomm reference device EC description
dt-bindings: pwm: add IPQ6018 binding
dt-bindings: hwmon: Add Apple System Management Controller hwmon schema
docs: dt: writing-schema: Clarify what is required in a schema
of: Respect #{iommu,msi}-cells in maps
of: Factor arguments passed to of_map_id() into a struct
of: Add convenience wrappers for of_map_id()
of: reserved_mem: zero total_reserved_mem_cnt if no valid /reserved-memory entry
of: reserved_mem: handle NULL name in of_reserved_mem_lookup()
dt-bindings: cache: l2c2x0: Add missing power-domains
dt-bindings: interrupt-controller: renesas,r9a09g077-icu: Fix reg size in example
dt-bindings: nvmem: consumer: Make 'nvmem' an array of one-item entries
drivers/of/overlay: Use memcpy() to copy known length strings
dt-bindings: add self-test fixtures for style checker
dt-bindings: wire style checker into dt_binding_check
scripts/jobserver-exec: propagate child exit status
dt-bindings: add DTS style checker
...
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git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
Pull slab updates from Vlastimil Babka:
- Support for "allocation tokens" (currently available in Clang 22+)
for smarter partitioning of kmalloc caches based on the allocated
object type, which can be enabled instead of the "random"
per-caller-address-hash partitioning.
It should be able to deterministically separate types containing a
pointer from those that do not (Marco Elver)
- Improvements and simplification of the kmem_cache_alloc_bulk() and
mempool_alloc_bulk() API. This includes adaptation of callers
(Christoph Hellwig)
- Performance improvements and cleanups related mostly to sheaves
refill (Hao Li, Shengming Hu, Vlastimil Babka)
- Several fixups for the slabinfo tool (Xuewen Wang)
* tag 'slab-for-7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
mm/slab: do not limit zeroing to orig_size when only red zoning is enabled
mm/slub: preserve original size in _kmalloc_nolock_noprof retry path
mm: simplify the mempool_alloc_bulk API
mm/slab: improve kmem_cache_alloc_bulk
mm/slub: detach and reattach partial slabs in batch
mm/slub: introduce helpers for node partial slab state
mm/slub: use empty sheaf helpers for oversized sheaves
tools/mm/slabinfo: remove redundant slab->partial assignment
tools/mm/slabinfo: remove dead assignment in get_obj_and_str()
tools/mm/slabinfo: Fix trace disable logic inversion
MAINTAINERS: add slab-related scripts and tools to SLAB ALLOCATOR
mm/slub: fix typo in sheaves comment
mm, slab: simplify returning slab in __refill_objects_node()
mm, slab: add an optimistic __slab_try_return_freelist()
slab: fix kernel-docs for mm-api
slab: improve KMALLOC_PARTITION_RANDOM randomness
slab: support for compiler-assisted type-based slab cache partitioning
mm/slub: defer freelist construction until after bulk allocation from a new slab
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Pull Rust updates from Miguel Ojeda:
"This one is big due to the vendoring of the `zerocopy` library, which
allows us to replace a bunch of `unsafe` code dealing with conversions
between byte sequences and other types with safe alternatives. More
details on that below (and in its merge commit).
Toolchain and infrastructure:
- Introduce support for the 'zerocopy' library [1][2]:
Fast, safe, compile error. Pick two.
Zerocopy makes zero-cost memory manipulation effortless. We write
`unsafe` so you don't have to.
It essentially provides derivable traits (e.g. 'FromBytes') and
macros (e.g. 'transmute!') for safely converting between byte
sequences and other types. Having such support allows us to remove
some 'unsafe' code.
It is among the most downloaded Rust crates and it is also used by
the Rust compiler itself.
It is licensed under "BSD-2-Clause OR Apache-2.0 OR MIT".
The crates are imported essentially as-is (only +2/-3 lines needed
to be adapted), plus SPDX identifiers. Upstream has since added the
SPDX identifiers as well as one of the tweaks at my request, thus
reducing our future diffs on updates -- I keep the details in one
of our usual live lists [3].
In total, it is about ~39k lines added, ~32k without counting
'benches/' which are just for documentation purposes.
The series includes a few Kbuild and rust-analyzer improvements and
an example patch using it in Nova, removing one 'unsafe impl'.
I checked that the codegen of an isolated example function (similar
to the Nova patch on top) is essentially identical. It also turns
out that (for that particular case) the 'zerocopy' version, even
with 'debug-assertions' enabled, has no remaining panics, unlike a
few in the current code (since the compiler can prove the remaining
'ub_checks' statically).
So their "fast, safe" does indeed check out -- at least in that
case.
- Support AutoFDO. This allows Rust code to be profiled and optimized
based on the profile. Tested with Rust Binder: ~13% slower without
AutoFDO in the binderAddInts benchmark (using an app-launch
benchmark for the profile).
- Support Software Tag-Based KASAN.
In addition, fix KASAN Kconfig by requiring Clang.
- Add Kconfig options for each existing Rust KUnit test suite, such
as 'CONFIG_RUST_BITMAP_KUNIT_TEST'.
They are placed within a new menu, 'CONFIG_RUST_KUNIT_TESTS', in
the new 'rust/kernel/Kconfig.test' file.
- Support the upcoming Rust 1.98.0 release (expected 2026-08-20):
lint cleanups and an unstable flag rename.
- Disable 'rustdoc' documentation inlining for all prelude items,
which bloats the generated documentation.
- Ignore (in Git) and clean (in Kbuild) the (rarely) 'rustc'-generated
'*.long-type-*.txt' files.
'kernel' crate:
- Add new 'bitfield' module with the 'bitfield!' macro (extracted
from the existing 'register!' one), which declares integer types
that are split into distinct bit fields of arbitrary length.
Each field is a 'Bounded' of the appropriate bit width (ensuring
values are properly validated and avoiding implicit data loss) and
gets several generated getters and setters (infallible, 'const' and
fallible) as well as associated constants ('_MASK', '_SHIFT' and
'_RANGE'). It also supports fields that can be converted from/to
custom types, either fallibly ('?=>') or infallibly ('=>').
For instance:
bitfield! {
struct Rgb(u16) {
15:11 blue;
10:5 green;
4:0 red;
}
}
// Compile-time checks.
let color = Rgb::zeroed().with_const_green::<0x1f>();
assert_eq!(color.green(), 0x1f);
assert_eq!(color.into_raw(), 0x1f << Rgb::GREEN_SHIFT);
Add as well documentation and a test suite for it, as usual; and
update the 'register!' macro to use it.
It will be maintained by Alexandre Courbot (with Yury Norov as
reviewer) under a new 'MAINTAINERS' entry: 'RUST [BITFIELD]'.
- 'ptr' module: rework index projection syntax into keyworded syntax
and introduce panicking variant.
The keyword syntax ('build:', 'try:', 'panic:') is more explicit
and paves the way of perhaps adding more flavors in the future,
e.g. an 'unsafe' index projection.
For instance, projections now look like this:
fn f(p: *const [u8; 32]) -> Result {
// Ok, within bounds, checked at build time.
project!(p, [build: 1]);
// Build error.
project!(p, [build: 128]);
// `OutOfBound` runtime error (convertible to `ERANGE`).
project!(p, [try: 128]);
// Runtime panic.
project!(p, [panic: 128]);
Ok(())
}
Update as well the users, which now look like e.g.
// Pointer to the first entry of the GSP message queue.
let data = project!(self.0.as_ptr(), .gspq.msgq.data[build: 0]);
- 'build_assert' module: make the module the home of its macros
instead of rendering them twice.
- 'sync' module: add 'UniqueArc::as_ptr()' associated function.
- 'alloc' module:
- Fix the 'Vec::reserve()' doctest to properly account for the
existing vector length in the capacity assertion.
- Fix an incorrect operator in the 'Vec::extend_with()' 'SAFETY'
comment; add a doc test demonstrating basic usage and the
zero-length case.
- Clean imports across several modules to follow the "kernel
vertical" import style in order to minimize conflicts.
'pin-init' crate:
- User visible changes:
- Do not generate 'non_snake_case' warnings for identifiers that
are syntactically just users of a field name. This would allow
all '#[allow(non_snake_case)]' in nova-core to be removed,
which Gary will send to the nova tree next cycle.
- Filter non-cfg attributes out properly in derived structs. This
improves pin-init compatibility with other derive macros.
- Insert projection types' where clause properly.
- Other changes:
- Bump MSRV to 1.82, plus associated cleanups.
- Overhaul how init slots are projected. The new approach is
easier to justify with safety comments.
- Mark more functions as inline, which should help mitigate the
super-long symbol name issue due to lack of inlining.
rust-analyzer:
- Support '--envs' for passing env vars for crates like 'zerocopy'.
'MAINTAINERS':
- Add the following reviewers to the 'RUST' entry:
- Daniel Almeida
- Tamir Duberstein
- Alexandre Courbot
- Onur Özkan
They have been involved in the Rust for Linux project for about 7
collective years and bring expertise across several domains, which
will be very useful to have around in the future.
Thanks everyone for stepping up!
And some other fixes, cleanups and improvements"
Link: https://github.com/google/zerocopy [1]
Link: https://docs.rs/zerocopy [2]
Link: https://github.com/Rust-for-Linux/linux/issues/1239 [3]
* tag 'rust-7.2' of gitolite.kernel.org:pub/scm/linux/kernel/git/ojeda/linux: (86 commits)
MAINTAINERS: add Onur Özkan as Rust reviewer
MAINTAINERS: add Alexandre Courbot as Rust reviewer
MAINTAINERS: add Tamir Duberstein as Rust reviewer
MAINTAINERS: add Daniel Almeida as Rust reviewer
kbuild: rust: clean `zerocopy-derive` in `mrproper`
rust: make `build_assert` module the home of related macros
rust: str: clean unused import for Rust >= 1.98
rust: str: use the "kernel vertical" imports style
rust: aref: use the "kernel vertical" imports style
rust: page: use the "kernel vertical" imports style
gpu: nova-core: firmware: parse `FalconUCodeDescV2` via `zerocopy`
rust: prelude: add `zerocopy{,_derive}::FromBytes`
rust: zerocopy-derive: enable support in kbuild
rust: zerocopy-derive: add `README.md`
rust: zerocopy-derive: avoid generating non-ASCII identifiers
rust: zerocopy-derive: add SPDX License Identifiers
rust: zerocopy-derive: import crate
rust: zerocopy: enable support in kbuild
rust: zerocopy: add `README.md`
rust: zerocopy: remove float `Display` support
...
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git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux
Pull Kbuild / Kconfig updates from Nathan Chancellor:
"Kbuild:
- Remove broken module linking exclusion for BTF
- Add documentation around how offset header files work
- Include unstripped vDSO libraries in pacman packages
- Bump minimum version of LLVM for building the kernel to 17.0.1 and
clean up unnecessary workarounds
- Use a context manager in run-clang-tools
- Add dist macro value if present to release tag for RPM packages
- Detect and report truncated buf_printf() output in modpost
- Add __llvm_covfun and __llvm_covmap to section whitelist in modpost
- Support Clang's distributed ThinLTO mode
- Remove architecture specific configurations for AutoFDO and
Propeller to ease individual architecture maintenance
Kconfig:
- Add kconfig-sym-check target to look for dangling Kconfig symbol
references and invalid tristate literal values
- Harden against potential NULL pointer dereference
- Fix typo in Kconfig test comment"
* tag 'kbuild-7.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (31 commits)
kconfig: tests: fix typo in comment
kconfig: Remove the architecture specific config for Propeller
kconfig: Remove the architecture specific config for AutoFDO
modpost: Add __llvm_covfun and __llvm_covmap to section_white_list
kconfig: add kconfig-sym-check static checker
kbuild: Remove unnecessary 'T' modifier in cmd_ar_builtin_fixup
kbuild: distributed build support for Clang ThinLTO
kbuild: move vmlinux.a build rule to scripts/Makefile.vmlinux_a
scripts: modpost: detect and report truncated buf_printf() output
kbuild: rpm-pkg: append %{?dist} macro to Release tag
run-clang-tools: run multiprocessing.Pool as context manager
compiler-clang.h: Drop explicit version number from "all" diagnostic macro
compiler-clang.h: Remove __cleanup -Wunused-variable workaround
kbuild: Remove check for broken scoping with clang < 17 in CC_HAS_ASM_GOTO_OUTPUT
x86/entry/vdso32: Remove conditional omission of '.cfi_offset eflags'
x86/module: Revert "Deal with GOT based stack cookie load on Clang < 17"
x86/build: Drop unnecessary '-ffreestanding' addition to KBUILD_CFLAGS
scripts/Makefile.warn: Drop -Wformat handling for clang < 16
riscv: Drop tautological condition from TOOLCHAIN_NEEDS_OLD_ISA_SPEC
riscv: Remove tautological condition from selection of ARCH_SUPPORTS_CFI
...
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Just like for the other two Rust proc macros, remove the artifacts in
`mrproper`.
This should have been part of commit 506054980429 ("rust: zerocopy-derive:
enable support in kbuild").
Link: https://patch.msgid.link/20260610143025.368801-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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Provide good/ and bad/ DTS and YAML fixtures plus a small runner that
feeds them to dt-check-style and diffs the output against expected
text files. Wired into a new top-level dt_style_selftest make target
so the suite can be exercised independently of the full tree.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Link: https://patch.msgid.link/80fec5d2cfcdee0f9c5e2d4921ebbd4115d392b7.1779908995.git.daniel@makrotopia.org
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
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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.
Link: https://patch.msgid.link/20260608141439.182634-18-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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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>
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git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux
Pull Rust fixes from Miguel Ojeda:
"Toolchain and infrastructure:
- Fix 'rustc-option' (the Makefile one) when cross-compiling that
leads to build or boot failures in certain configs
- Work around a Rust compiler bug (already fixed for Rust 1.98.0)
thats lead to boot failures in certain configs due to missing
'uwtable' LLVM module flags
- Support a Rust compiler change (starting with Rust 1.98.0) in the
unstable target specification JSON files
- Forbid Rust + arm + KASAN configs, which do not build
'kernel' crate:
- Fix NOMMU build by adding a missing helper"
* tag 'rust-fixes-7.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
rust: x86: support Rust >= 1.98.0 target spec
rust: arm64: set uwtable llvm module flag for CONFIG_UNWIND_TABLES
rust: helpers: add is_vmalloc_addr wrapper for NOMMU builds
rust: kasan/kbuild: fix rustc-option when cross-compiling
ARM: Do not select HAVE_RUST when KASAN is enabled
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Add 'make kconfig-sym-check', a static checker that finds Kconfig
symbols referenced in expressions (select, depends on, default, etc.)
but never defined via config/menuconfig anywhere in the tree. New
dangling symbols are reported as errors (exit 1) unless they are
listed in an exclusion file, e.g.
KCONFIG_SYM_CHECK_EXCLUDES=sym-check-excludes make kconfig-sym-check
The exclusion file lists one symbol per line; blank lines and lines
starting with '#' are ignored.
The checker also warns about uppercase N/Y/M used as tristate literal
values following the same logic as checkpatch.
This new static checker is the script used for [1] with a few
improvements to avoid some false positives.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216748 [1]
Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Julian Braha <julianbraha@gmail.com>
Tested-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Nicolas Schier <nsc@kernel.org>
Link: https://patch.msgid.link/20260527142703.107110-1-andrew.jones@linux.dev
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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When rustc prints an error containing a long type that doesn't fit
in a line, it will write the whole thing in a .txt file -- see commit
420dd187e157 (".gitignore: ignore rustc long type txt files") for more
details.
These files are purely compiler artifacts and are not created
intentionally by the build system.
Thus add them to the `clean` target to stop them from cluttering up the
source tree.
Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/Rust-for-Linux/linux/issues/1236
Signed-off-by: Joel Kamminga <contact@jkam.dev>
Acked-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260530184944.10459-1-contact@jkam.dev
[ Reworded and linked to the previous related commit. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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Add distributed ThinLTO build support for the Linux kernel.
This new mode offers several advantages: (1) Increased
flexibility in handling user-specified build options.
(2) Improved user-friendliness for developers. (3) Greater
convenience for integrating with objtool and livepatch.
Note that "distributed" in this context refers to a term
that differentiates in-process ThinLTO builds by invoking
backend compilation through the linker, not necessarily
building in distributed environments.
Distributed ThinLTO is enabled via the
`CONFIG_LTO_CLANG_THIN_DIST` Kconfig option. For example:
> make LLVM=1 defconfig
> scripts/config -e LTO_CLANG_THIN_DIST
> make LLVM=1 oldconfig
> make LLVM=1 vmlinux -j <..>
The build flow proceeds in four stages:
1. Perform FE compilation, mirroring the in-process ThinLTO mode.
2. Thin-link the generated IR files and object files.
3. Find all IR files and perform BE compilation, using the flags
stored in the .*.o.cmd files.
4. Link the BE results to generate the final vmlinux.o.
NOTE: This patch currently implements the build for the main kernel
image (vmlinux) only. Kernel module support is planned for a
subsequent patch.
Tested on the following arch: x86, arm64, loongarch, and
riscv.
The earlier implementation details can be found here:
https://discourse.llvm.org/t/rfc-distributed-thinlto-build-for-kernel/85934
Signed-off-by: Rong Xu <xur@google.com>
Co-developed-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Piotr Gorski <piotrgorski@cachyos.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260529185347.2418373-4-xur@google.com
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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Move the build rule for vmlinux.a to a separate file in preparation
for supporting distributed builds with Clang ThinLTO.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Rong Xu <xur@google.com>
Tested-by: Piotr Gorski <piotrgorski@cachyos.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Rong Xu <xur@google.com>
Link: https://patch.msgid.link/20260529185347.2418373-2-xur@google.com
[nathan: Squash in forward fix from Rong around '--thin' to $(AR)
https://patch.msgid.link/20260529185347.2418373-3-xur@google.com]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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The Makefile version of rustc-option currently checks whether the option
exists for the host target instead of the target actually being compiled
for. It was done this way in commit 46e24a545cdb ("rust: kasan/kbuild:
fix missing flags on first build") to avoid a circular dependency on
target.json. However, because of this, rustc-option currently does not
function when cross-compiling from x86_64 to aarch64 if
CONFIG_SHADOW_CALL_STACK is enabled. This is because KBUILD_RUSTFLAGS
contains -Zfixed-x18 under this configuration. Since that flag does not
exist on the host target, rustc-option runs into a compilation failure
every time, leading to all flags being rejected as unsupported.
To fix this, update rustc-option to pass a --target parameter so that
the host target is not used. For targets using target.json, use a
built-in target that is as close as possible to the target created with
target.json to avoid the circular dependency on target.json.
One scenario where this causes a boot failure:
* Cross-compiled from x86_64 to aarch64.
* With CONFIG_SHADOW_CALL_STACK=y
* With CONFIG_KASAN_SW_TAGS=y
* With CONFIG_KASAN_INLINE=n
Then the resulting kernel image will fail to boot when it first calls
into Rust code with a crash along the lines of "Unable to handle kernel
paging request at virtual address 0ffffffc08541796". This is because the
call threshold is not specified, so rustc will inline kasan operations,
but the kasan shadow offset is not specified, which leads to the inlined
kasan instructions being incorrect.
Note that the -Zsanitizer=kernel-hwaddress parameter itself does not
lead to a rustc-option failure despite being aarch64-specific because
RUSTFLAGS_KASAN has not yet been added to KBUILD_RUSTFLAGS when
rustc-option is evaluated by the kasan Makefile.
Cc: stable@vger.kernel.org
Fixes: 46e24a545cdb ("rust: kasan/kbuild: fix missing flags on first build")
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Link: https://patch.msgid.link/20260507-rustc-option-cross-v2-1-2f650a49c2b5@google.com
[ Edited slightly:
- Reset variable to avoid using the environment.
- Use a simply expanded variable flavor for simplicity.
- Export variable so that behavior in sub-`make`s is consistent.
This matches other variables. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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Rework the general infrastructure around RANDOM_KMALLOC_CACHES into more
flexible KMALLOC_PARTITION_CACHES, with the former being a partitioning
mode of the latter.
Introduce a new mode, KMALLOC_PARTITION_TYPED, which leverages a feature
available in Clang 22 and later, called "allocation tokens" via
__builtin_infer_alloc_token() [1]. Unlike KMALLOC_PARTITION_RANDOM
(formerly RANDOM_KMALLOC_CACHES), this mode deterministically assigns a
slab cache to an allocation of type T, regardless of allocation site.
The builtin __builtin_infer_alloc_token(<malloc-args>, ...) instructs
the compiler to infer an allocation type from arguments commonly passed
to memory-allocating functions and returns a type-derived token ID. The
implementation passes kmalloc-args to the builtin: the compiler performs
best-effort type inference, and then recognizes common patterns such as
`kmalloc(sizeof(T), ...)`, `kmalloc(sizeof(T) * n, ...)`, but also
`(T *)kmalloc(...)`. Where the compiler fails to infer a type the
fallback token (default: 0) is chosen.
Note: kmalloc_obj(..) APIs fix the pattern how size and result type are
expressed, and therefore ensures there's not much drift in which
patterns the compiler needs to recognize. Specifically, kmalloc_obj()
and friends expand to `(TYPE *)KMALLOC(__obj_size, GFP)`, which the
compiler recognizes via the cast to TYPE*.
Clang's default token ID calculation is described as [1]:
typehashpointersplit: This mode assigns a token ID based on the hash
of the allocated type's name, where the top half ID-space is reserved
for types that contain pointers and the bottom half for types that do
not contain pointers.
Separating pointer-containing objects from pointerless objects and data
allocations can help mitigate certain classes of memory corruption
exploits [2]: attackers who gains a buffer overflow on a primitive
buffer cannot use it to directly corrupt pointers or other critical
metadata in an object residing in a different, isolated heap region.
It is important to note that heap isolation strategies offer a
best-effort approach, and do not provide a 100% security guarantee,
albeit achievable at relatively low performance cost. Note that this
also does not prevent cross-cache attacks: while waiting for future
features like SLAB_VIRTUAL [3] to provide physical page isolation, this
feature should be deployed alongside SHUFFLE_PAGE_ALLOCATOR and
init_on_free=1 to mitigate cross-cache attacks and page-reuse attacks as
much as possible today.
With all that, my kernel (x86 defconfig) shows me a histogram of slab
cache object distribution per /proc/slabinfo (after boot):
<slab cache> <objs> <hist>
kmalloc-part-15 1465 ++++++++++++++
kmalloc-part-14 2988 +++++++++++++++++++++++++++++
kmalloc-part-13 1656 ++++++++++++++++
kmalloc-part-12 1045 ++++++++++
kmalloc-part-11 1697 ++++++++++++++++
kmalloc-part-10 1489 ++++++++++++++
kmalloc-part-09 965 +++++++++
kmalloc-part-08 710 +++++++
kmalloc-part-07 100 +
kmalloc-part-06 217 ++
kmalloc-part-05 105 +
kmalloc-part-04 4047 ++++++++++++++++++++++++++++++++++++++++
kmalloc-part-03 183 +
kmalloc-part-02 283 ++
kmalloc-part-01 316 +++
kmalloc 1422 ++++++++++++++
The above /proc/slabinfo snapshot shows me there are 6673 allocated
objects (slabs 00 - 07) that the compiler claims contain no pointers or
it was unable to infer the type of, and 12015 objects that contain
pointers (slabs 08 - 15). On a whole, this looks relatively sane.
Additionally, when I compile my kernel with -Rpass=alloc-token, which
provides diagnostics where (after dead-code elimination) type inference
failed, I see 186 allocation sites where the compiler failed to identify
a type (down from 966 when I sent the RFC [4]). Some initial review
confirms these are mostly variable sized buffers, but also include
structs with trailing flexible length arrays.
Link: https://clang.llvm.org/docs/AllocToken.html [1]
Link: https://blog.dfsec.com/ios/2025/05/30/blasting-past-ios-18/ [2]
Link: https://lwn.net/Articles/944647/ [3]
Link: https://lore.kernel.org/all/20250825154505.1558444-1-elver@google.com/ [4]
Link: https://discourse.llvm.org/t/rfc-a-framework-for-allocator-partitioning-hints/87434
Acked-by: GONG Ruiqi <gongruiqi1@huawei.com>
Co-developed-by: Harry Yoo (Oracle) <harry@kernel.org>
Signed-off-by: Harry Yoo (Oracle) <harry@kernel.org>
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org>
Link: https://patch.msgid.link/20260511200136.3201646-1-elver@google.com
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux
Pull Rust fixes from Miguel Ojeda:
"Toolchain and infrastructure:
- Add 'bindgen' target to make UML 32-bit builds work with GCC
- Disable two Clippy warnings ('collapsible_{if,match}')
'pin-init' crate:
- Fix unsoundness issue that created &'static references"
* tag 'rust-fixes-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
rust: allow `clippy::collapsible_if` globally
rust: allow `clippy::collapsible_match` globally
rust: pin-init: fix incorrect accessor reference lifetime
rust: pin-init: internal: move alignment check to `make_field_check`
rust: arch: um: Fix building 32-bit UML with GCC
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|
Similar to `clippy::collapsible_match` (globally allowed in the previous
commit), the `clippy::collapsible_if` lint [1] can make code harder to
read in certain cases.
Thus just let developers decide on their own.
In addition, remove the existing `expect` we had.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Suggested-by: Gary Guo <gary@garyguo.net>
Link: https://lore.kernel.org/rust-for-linux/DGROP5CHU1QZ.1OKJRAUZXE9WC@garyguo.net/
Link: https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if [1]
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260426144201.227108-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
|
|
The `clippy::collapsible_match` lint [1] can make code harder to read
in certain cases [2], e.g.
CLIPPY P rust/libmacros.so - due to command line change
warning: this `if` can be collapsed into the outer `match`
--> rust/pin-init/internal/src/helpers.rs:91:17
|
91 | / if nesting == 1 {
92 | | impl_generics.push(tt.clone());
93 | | impl_generics.push(tt);
94 | | skip_until_comma = false;
95 | | }
| |_________________^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_match
= note: `-W clippy::collapsible-match` implied by `-W clippy::all`
= help: to override `-W clippy::all` add `#[allow(clippy::collapsible_match)]`
help: collapse nested if block
|
90 ~ TokenTree::Punct(p) if skip_until_comma && p.as_char() == ','
91 ~ && nesting == 1 => {
92 | impl_generics.push(tt.clone());
93 | impl_generics.push(tt);
94 | skip_until_comma = false;
95 ~ }
|
The lint does not have much upside -- when the suggestion may be a good
one, it would still read fine when nested anyway. And it is the kind of
lint that may easily bias people to just apply the suggestion instead
of allowing it.
[ In addition, as Gary points out [3], the suggestion is also wrong [4] and
in the process of being fixed [5], possibly for Rust 1.97.0:
Link: https://lore.kernel.org/rust-for-linux/DI3YV94TH9I3.1SOHW51552497@garyguo.net/ [3]
Link: https://github.com/rust-lang/rust-clippy/issues/16875 [4]
Link: https://github.com/rust-lang/rust-clippy/pull/16878 [5]
- Miguel ]
Thus just let developers decide on their own.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_match [1]
Link: https://lore.kernel.org/rust-for-linux/CANiq72nWYJna_hdFxjQCQZK6yJBrr1Mb86iKavivV0U0BgufeA@mail.gmail.com/ [2]
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260426144201.227108-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux
Pull Kbuild fixes from Nicolas Schier:
- builddeb - avoid recompiles for non-cross-compiles
Avoid triggering complete rebuilds for non-cross-compile Debian
package builds by only triggering the rebuild of host tools for
actual cross-compile builds
- Never respect CONFIG_WERROR / W=e to fixdep
Avoid spurious rebuilds of fixdep w/ and w/o -Werror during a single
kbuild invocation by never respecting CONFIG_WERROR for fixdep
* tag 'kbuild-fixes-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
kbuild: Never respect CONFIG_WERROR / W=e to fixdep
kbuild: builddeb - avoid recompiles for non-cross-compiles
|
|
The fixdep hostprog may be built multiple times during a single build.
Once during the configuration phase and later during the regular phase.
As only the regular build phase respects CONFIG_WERROR / W=e, the
compiler flags might change between the phases, leading to rebuilds.
Example, the rebuilds will happen twice on each invocation of the build:
$ make allyesconfig prepare
make[1]: Entering directory '/tmp/deleteme'
HOSTCC scripts/basic/fixdep
#
# No change to .config
#
HOSTCC scripts/basic/fixdep
DESCEND objtool
INSTALL libsubcmd_headers
make[1]: Leaving directory '/tmp/deleteme'
Fix the compilation flags used for scripts/basic/ before
scripts/Makefile.warn is evaluated to stop CONFIG_WERROR / W=e
influencing the fixdep build to avoid the spurious rebuilds.
Fixes: 7ded7d37e5f5 ("scripts/Makefile.extrawarn: Respect CONFIG_WERROR / W=e for hostprogs")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260422-kbuild-scripts-basic-werror-v1-1-8c6912ff22e0@weissschuh.net
Signed-off-by: Nicolas Schier <nsc@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux
Pull Kbuild/Kconfig updates from Nicolas Schier:
"Kbuild:
- reject unexpected values for LLVM=
- uapi: remove usage of toolchain headers
- switch from '-fms-extensions' to '-fms-anonymous-structs' when
available (currently: clang >= 23.0.0)
- reduce the number of compiler-generated suffixes for clang thin-lto
build
- reduce output spam ("GEN Makefile") when building out of tree
- improve portability for testing headers
- also test UAPI headers against C++ compilers
- drop build ID architecture allow-list in vdso_install
- only run checksyscalls when necessary
- update the debug information notes in reproducible-builds.rst
- expand inlining hints with -fdiagnostics-show-inlining-chain
Kconfig:
- forbid multiple entries with the same symbol in a choice
- error out on duplicated kconfig inclusion"
* tag 'kbuild-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux: (35 commits)
kbuild: expand inlining hints with -fdiagnostics-show-inlining-chain
kconfig: forbid multiple entries with the same symbol in a choice
Documentation: kbuild: Update the debug information notes in reproducible-builds.rst
checksyscalls: move instance functionality into generic code
checksyscalls: only run when necessary
checksyscalls: fail on all intermediate errors
checksyscalls: move path to reference table to a variable
kbuild: vdso_install: drop build ID architecture allow-list
kbuild: vdso_install: gracefully handle images without build ID
kbuild: vdso_install: hide readelf warnings
kbuild: vdso_install: split out the readelf invocation
kbuild: uapi: also test UAPI headers against C++ compilers
kbuild: uapi: provide a C++ compatible dummy definition of NULL
kbuild: uapi: handle UML in architecture-specific exclusion lists
kbuild: uapi: move all include path flags together
kbuild: uapi: move some compiler arguments out of the command definition
check-uapi: use dummy libc includes
check-uapi: honor ${CROSS_COMPILE} setting
check-uapi: link into shared objects
kbuild: reduce output spam when building out of tree
...
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git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux
Pull Rust updates from Miguel Ojeda:
"Toolchain and infrastructure:
- Bump the minimum Rust version to 1.85.0 (and 'bindgen' to 0.71.1).
As proposed in LPC 2025 and the Maintainers Summit [1], we are
going to follow Debian Stable's Rust versions as our minimum
versions.
Debian Trixie was released on 2025-08-09 with a Rust 1.85.0 and
'bindgen' 0.71.1 toolchain, which is a fair amount of time for e.g.
kernel developers to upgrade.
Other major distributions support a Rust version that is high
enough as well, including:
+ Arch Linux.
+ Fedora Linux.
+ Gentoo Linux.
+ Nix.
+ openSUSE Slowroll and openSUSE Tumbleweed.
+ Ubuntu 25.10 and 26.04 LTS. In addition, 24.04 LTS using
their versioned packages.
The merged patch series comes with the associated cleanups and
simplifications treewide that can be performed thanks to both
bumps, as well as documentation updates.
In addition, start using 'bindgen''s '--with-attribute-custom-enum'
feature to set the 'cfi_encoding' attribute for the 'lru_status'
enum used in Binder.
Link: https://lwn.net/Articles/1050174/ [1]
- Add experimental Kconfig option ('CONFIG_RUST_INLINE_HELPERS') that
inlines C helpers into Rust.
Essentially, it performs a step similar to LTO, but just for the
helpers, i.e. very local and fast.
It relies on 'llvm-link' and its '--internalize' flag, and requires
a compatible LLVM between Clang and 'rustc' (i.e. same major
version, 'CONFIG_RUSTC_CLANG_LLVM_COMPATIBLE'). It is only enabled
for two architectures for now.
The result is a measurable speedup in different workloads that
different users have tested. For instance, for the null block
driver, it amounts to a 2%.
- Support global per-version flags.
While we already have per-version flags in many places, we didn't
have a place to set global ones that depend on the compiler
version, i.e. in 'rust_common_flags', which sometimes is needed to
e.g. tweak the lints set per version.
Use that to allow the 'clippy::precedence' lint for Rust < 1.86.0,
since it had a change in behavior.
- Support overriding the crate name and apply it to Rust Binder,
which wanted the module to be called 'rust_binder'.
- Add the remaining '__rust_helper' annotations (started in the
previous cycle).
'kernel' crate:
- Introduce the 'const_assert!' macro: a more powerful version of
'static_assert!' that can refer to generics inside functions or
implementation bodies, e.g.:
fn f<const N: usize>() {
const_assert!(N > 1);
}
fn g<T>() {
const_assert!(size_of::<T>() > 0, "T cannot be ZST");
}
In addition, reorganize our set of build-time assertion macros
('{build,const,static_assert}!') to live in the 'build_assert'
module.
Finally, improve the docs as well to clarify how these are
different from one another and how to pick the right one to use,
and their equivalence (if any) to the existing C ones for extra
clarity.
- 'sizes' module: add 'SizeConstants' trait.
This gives us typed 'SZ_*' constants (avoiding casts) for use in
device address spaces where the address width depends on the
hardware (e.g. 32-bit MMIO windows, 64-bit GPU framebuffers, etc.),
e.g.:
let gpu_heap = 14 * u64::SZ_1M;
let mmio_window = u32::SZ_16M;
- 'clk' module: implement 'Send' and 'Sync' for 'Clk' and thus
simplify the users in Tyr and PWM.
- 'ptr' module: add 'const_align_up'.
- 'str' module: improve the documentation of the 'c_str!' macro to
explain that one should only use it for non-literal cases (for the
other case we instead use C string literals, e.g. 'c"abc"').
- Disallow the use of 'CStr::{as_ptr,from_ptr}' and clean one such
use in the 'task' module.
- 'sync' module: finish the move of 'ARef' and 'AlwaysRefCounted'
outside of the 'types' module, i.e. update the last remaining
instances and finally remove the re-exports.
- 'error' module: clarify that 'from_err_ptr' can return 'Ok(NULL)',
including runtime-tested examples.
The intention is to hopefully prevent UB that assumes the result of
the function is not 'NULL' if successful. This originated from a
case of UB I noticed in 'regulator' that created a 'NonNull' on it.
Timekeeping:
- Expand the example section in the 'HrTimer' documentation.
- Mark the 'ClockSource' trait as unsafe to ensure valid values for
'ktime_get()'.
- Add 'Delta::from_nanos()'.
'pin-init' crate:
- Replace the 'Zeroable' impls for 'Option<NonZero*>' with impls of
'ZeroableOption' for 'NonZero*'.
- Improve feature gate handling for unstable features.
- Declutter the documentation of implementations of 'Zeroable' for
tuples.
- Replace uses of 'addr_of[_mut]!' with '&raw [mut]'.
rust-analyzer:
- Add type annotations to 'generate_rust_analyzer.py'.
- Add support for scripts written in Rust ('generate_rust_target.rs',
'rustdoc_test_builder.rs', 'rustdoc_test_gen.rs').
- Refactor 'generate_rust_analyzer.py' to explicitly identify host
and target crates, improve readability, and reduce duplication.
And some other fixes, cleanups and improvements"
* tag 'rust-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux: (79 commits)
rust: sizes: add SizeConstants trait for device address space constants
rust: kernel: update `file_with_nul` comment
rust: kbuild: allow `clippy::precedence` for Rust < 1.86.0
rust: kbuild: support global per-version flags
rust: declare cfi_encoding for lru_status
docs: rust: general-information: use real example
docs: rust: general-information: simplify Kconfig example
docs: rust: quick-start: remove GDB/Binutils mention
docs: rust: quick-start: remove Nix "unstable channel" note
docs: rust: quick-start: remove Gentoo "testing" note
docs: rust: quick-start: add Ubuntu 26.04 LTS and remove subsection title
docs: rust: quick-start: update minimum Ubuntu version
docs: rust: quick-start: update Ubuntu versioned packages
docs: rust: quick-start: openSUSE provides `rust-src` package nowadays
rust: kbuild: remove "dummy parameter" workaround for `bindgen` < 0.71.1
rust: kbuild: update `bindgen --rust-target` version and replace comment
rust: rust_is_available: remove warning for `bindgen` < 0.69.5 && libclang >= 19.1
rust: rust_is_available: remove warning for `bindgen` 0.66.[01]
rust: bump `bindgen` minimum supported version to 0.71.1 (Debian Trixie)
rust: block: update `const_refs_to_static` MSRV TODO comment
...
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https://github.com/Rust-for-Linux/linux into rust-next
Pull timekeeping updates from Andreas Hindborg:
- Expand the example section in the 'HrTimer' documentation.
- Mark the 'ClockSource' trait as unsafe to ensure valid values for
'ktime_get()'.
- Add 'Delta::from_nanos()'.
This is a back merge since the pull request has a newer base -- we will
avoid that in the future.
And, given it is a back merge, it happens to resolve the "subtle" conflict
around '--remap-path-{prefix,scope}' that I discussed in linux-next [1],
plus a few other common conflicts. The result matches what we did for
next-20260407.
The actual diffstat (i.e. using a temporary merge of upstream first) is:
rust/kernel/time.rs | 32 ++++-
rust/kernel/time/hrtimer.rs | 336 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 362 insertions(+), 6 deletions(-)
Link: https://lore.kernel.org/linux-next/CANiq72kdxB=W3_CV1U44oOK3SssztPo2wLDZt6LP94TEO+Kj4g@mail.gmail.com/ [1]
* tag 'rust-timekeeping-for-v7.1' of https://github.com/Rust-for-Linux/linux:
hrtimer: add usage examples to documentation
rust: time: make ClockSource unsafe trait
rust/time: Add Delta::from_nanos()
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Clang recently added -fdiagnostics-show-inlining-chain [1] to improve
the visibility of inlining chains in diagnostics. This is particularly
useful for CONFIG_FORTIFY_SOURCE where detections can happen deep in
inlined functions.
Add this flag to KBUILD_CFLAGS under a cc-option so it is enabled if the
compiler supports it. Note that GCC does not have an equivalent flag as
it supports a similar diagnostic structure unconditionally.
Link: https://github.com/llvm/llvm-project/pull/174892 [1]
Link: https://github.com/ClangBuiltLinux/linux/issues/1571
Signed-off-by: Justin Stitt <justinstitt@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Link: https://patch.msgid.link/20260330-kbuild-show-inlining-v2-1-c0c481a4ea7b@google.com
Signed-off-by: Nicolas Schier <nsc@kernel.org>
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The Clippy `precedence` lint was extended in Rust 1.85.0 to include
bitmasking and shift operations [1]. 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 [2].
In other words, only Rust 1.85 has a different behavior. For instance,
it reports:
warning: operator precedence can trip the unwary
--> drivers/gpu/nova-core/fb/hal/ga100.rs:16:5
|
16 | / u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::read(bar).adr_39_08()) << FLUSH_SYSMEM_ADDR_SHIFT
17 | | | u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI::read(bar).adr_63_40())
18 | | << FLUSH_SYSMEM_ADDR_SHIFT_HI
| |_________________________________________^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#precedence
= note: `-W clippy::precedence` implied by `-W clippy::all`
= help: to override `-W clippy::all` add `#[allow(clippy::precedence)]`
help: consider parenthesizing your expression
|
16 ~ (u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::read(bar).adr_39_08()) << FLUSH_SYSMEM_ADDR_SHIFT) | (u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI::read(bar).adr_63_40())
17 + << FLUSH_SYSMEM_ADDR_SHIFT_HI)
|
While so far we try our best to keep all versions Clippy-clean, the
minimum (which is now Rust 1.85.0 after the bump) and the latest stable
are the most important ones; and this may be considered a "false positive"
with respect to the behavior in other versions.
Thus allow this lint for this version using the per-version flags
mechanism introduced in the previous commit.
Link: https://github.com/rust-lang/rust-clippy/issues/14097 [1]
Link: https://github.com/rust-lang/rust-clippy/pull/14115 [2]
Link: https://lore.kernel.org/rust-for-linux/DFVDKMMA7KPC.2DN0951H3H55Y@kernel.org/
Reviewed-by: Tamir Duberstein <tamird@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260405235309.418950-34-ojeda@kernel.org
[ Added paragraph from commit message to comment. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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Sometimes it is useful to gate global Rust flags per compiler version.
For instance, we may want to disable a lint that has false positives in
a single version [1].
We already had helpers like `rustc-min-version` for that, which we use
elsewhere, but we cannot currently use them for `rust_common_flags`,
which contains the global flags for all Rust code (kernel and host),
because `rustc-min-version` depends on `CONFIG_RUSTC_VERSION`, which
does not exist when `rust_common_flags` is defined.
Thus, to support that, introduce `rust_common_flags_per_version`,
defined after the `include/config/auto.conf` inclusion (where
`CONFIG_RUSTC_VERSION` becomes available), and append it to
`rust_common_flags`, `KBUILD_HOSTRUSTFLAGS` and `KBUILD_RUSTFLAGS`.
In addition, move the expansion of `HOSTRUSTFLAGS` to the same place,
so that users can also override per-version flags [2].
Link: https://lore.kernel.org/rust-for-linux/CANiq72mWdFU11GcCZRchzhy0Gi1QZShvZtyRkHV2O+WA2uTdVQ@mail.gmail.com/ [1]
Link: https://lore.kernel.org/rust-for-linux/CANiq72mTaA2tjhkLKf0-2hrrrt9rxWPgy6SfNSbponbGOegQvA@mail.gmail.com/ [2]
Link: https://patch.msgid.link/20260307170929.153892-1-ojeda@kernel.org
Link: https://patch.msgid.link/20260405235309.418950-33-ojeda@kernel.org
Reviewed-by: Tamir Duberstein <tamird@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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`clippy::incompatible_msrv` is not buying us much, and we discussed
allowing it several times in the past.
For instance, there was recently another patch sent to `allow` it where
needed [1]. While that particular case would not be needed after the
minimum version bump to 1.85.0, it is simpler to just allow it to prevent
future instances.
[ In addition, the lint fired without taking into account the features
that have been enabled in a crate [2]. While this was improved in Rust
1.90.0 [3], it would still fire in a case like this patch. ]
Thus do so, and remove the last instance of locally allowing it we have
in the tree (except the one in the vendored `proc_macro2` crate).
Note that we still keep the `msrv` config option in `clippy.toml` since
that affects other lints as well.
Link: https://lore.kernel.org/rust-for-linux/20260404212831.78971-4-jhubbard@nvidia.com/ [1]
Link: https://github.com/rust-lang/rust-clippy/issues/14425 [2]
Link: https://github.com/rust-lang/rust-clippy/pull/14433 [3]
Link: https://patch.msgid.link/20260405235309.418950-8-ojeda@kernel.org
Reviewed-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Tamir Duberstein <tamird@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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Clippy in Rust 1.88.0 (only) reports [1]:
warning: variables can be used directly in the `format!` string
--> rust/macros/module.rs:112:23
|
112 | let content = format!("{param}:{content}", param = param, content = content);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
= note: `-W clippy::uninlined-format-args` implied by `-W clippy::all`
= help: to override `-W clippy::all` add `#[allow(clippy::uninlined_format_args)]`
help: change this to
|
112 - let content = format!("{param}:{content}", param = param, content = content);
112 + let content = format!("{param}:{content}");
warning: variables can be used directly in the `format!` string
--> rust/macros/module.rs:198:14
|
198 | t => panic!("Unsupported parameter type {}", t),
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
= note: `-W clippy::uninlined-format-args` implied by `-W clippy::all`
= help: to override `-W clippy::all` add `#[allow(clippy::uninlined_format_args)]`
help: change this to
|
198 - t => panic!("Unsupported parameter type {}", t),
198 + t => panic!("Unsupported parameter type {t}"),
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The reason it only triggers in that version is that the lint was moved
from `pedantic` to `style` in Rust 1.88.0 and then back to `pedantic`
in Rust 1.89.0 [2][3].
In the first case, the suggestion is fair and a pure simplification, thus
we will clean it up separately.
To keep the behavior the same across all versions, and since the lint
does not work for all macros (e.g. custom ones like `pr_info!`), disable
it globally.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://lore.kernel.org/rust-for-linux/CANiq72=drAtf3y_DZ-2o4jb6Az9J3Yj4QYwWnbRui4sm4AJD3Q@mail.gmail.com/ [1]
Link: https://github.com/rust-lang/rust-clippy/pull/15287 [2]
Link: https://github.com/rust-lang/rust-clippy/issues/15151 [3]
Link: https://patch.msgid.link/20260331205849.498295-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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A new experimental Kconfig option, `RUST_INLINE_HELPERS` is added to
allow C helpers (which were created to allow Rust to call into
inline/macro C functions without having to re-implement the logic in
Rust) to be inlined into Rust crates without performing global LTO.
If the option is enabled, the following is performed:
* For helpers, instead of compiling them to an object file to be linked
into vmlinux, they're compiled to LLVM IR bitcode. Two versions are
generated: one for built-in code (`helpers.bc`) and one for modules
(`helpers_module.bc`, with -DMODULE defined). This ensures that C
macros/inlines that behave differently for modules (e.g. static calls)
function correctly when inlined.
* When a Rust crate or object is compiled, instead of generating an
object file, LLVM bitcode is generated.
* llvm-link is invoked with --internalize to combine the helper bitcode
with the crate bitcode. This step is similar to LTO, but this is much
faster since it only needs to inline the helpers.
* clang is invoked to turn the combined bitcode into a final object file.
* Since clang may produce LLVM bitcode when LTO is enabled, and objtool
requires ELF input, $(cmd_ld_single) is invoked to ensure the object
is converted to ELF before objtool runs.
The --internalize flag tells llvm-link to treat all symbols in
helpers.bc using `internal` linkage [1]. This matches the behavior of
`clang` on `static inline` functions, and avoids exporting the symbol
from the object file.
To ensure that RUST_INLINE_HELPERS is not incompatible with BTF, we pass
the -g0 flag when building helpers. See commit 5daa0c35a1f0 ("rust:
Disallow BTF generation with Rust + LTO") for details.
We have an intended triple mismatch of `aarch64-unknown-none` vs
`aarch64-unknown-linux-gnu`, so we pass --suppress-warnings to llvm-link
to suppress it.
I considered adding some sort of check that KBUILD_MODNAME is not
present in helpers_module.bc, but this is actually not so easy to carry
out because .bc files store strings in a weird binary format, so you
cannot just grep it for a string to check whether it ended up using
KBUILD_MODNAME anywhere.
[ Andreas writes:
For the rnull driver, enabling helper inlining with this patch
gives an average speedup of 2% over the set of 120 workloads that
we publish on [2].
Link: https://rust-for-linux.com/null-block-driver [2]
This series also uncovered a pre-existing UB instance thanks to an
`objtool` warning which I noticed while testing the series (details
in the mailing list).
- Miguel ]
Link: https://github.com/llvm/llvm-project/pull/170397 [1]
Co-developed-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Co-developed-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Matthew Maurer <mmaurer@google.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Co-developed-by: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Reviewed-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://patch.msgid.link/20260203-inline-helpers-v2-3-beb8547a03c9@google.com
[ Some changes, apart from the rebase:
- Added "(EXPERIMENTAL)" to Kconfig as the commit mentions.
- Added `depends on ARM64 || X86_64` and `!UML` for now, since this is
experimental, other architectures may require other changes (e.g.
the issues I mentioned in the mailing list for ARM and UML) and they
are not really tested so far. So let arch maintainers pick this up
if they think it is worth it.
- Gated the `cmd_ld_single` step also into the new mode, which also
means that any possible future `objcopy` step is done after the
translation, as expected.
- Added `.gitignore` for `.bc` with exception for existing script.
- Added `part-of-*` for helpers bitcode files as discussed, and
dropped `$(if $(filter %_module.bc,$@),-DMODULE)` since `-DMODULE`
is already there (would be duplicated otherwise).
- Moved `LLVM_LINK` to keep binutils list alphabetized.
- Fixed typo in title.
- Dropped second `cmd_ld_single` commit message paragraph.
- Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux
Pull Kbuild fixes from Nathan Chancellor:
"This mostly addresses some issues with the awk conversion in
scripts/kconfig/merge_config.sh.
- Fix typo to ensure .builtin-dtbs.S is properly cleaned
- Fix '==' bashism in scripts/kconfig/merge_config.sh
- Fix awk error in scripts/kconfig/merge_config.sh when base
configuration is empty
- Fix inconsistent indentation in scripts/kconfig/merge_config.sh"
* tag 'kbuild-fixes-7.0-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kbuild/linux:
scripts: kconfig: merge_config.sh: fix indentation
scripts: kconfig: merge_config.sh: pass output file as awk variable
scripts: kconfig: merge_config.sh: fix unexpected operator warning
kbuild: Delete .builtin-dtbs.S when running make clean
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The execution of $(call cmd,makefile) will print 'GEN Makefile' on each
build, even if the Makefile is not effectively changed.
Use a filechk command instead, so a message is only printed on changes.
The Makefile is now created even if the build is aborted due to an
unclean working tree. That should not make a difference in practice.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260305-kbuild-makefile-spam-v1-1-910f6cf218a1@linutronix.de
Signed-off-by: Nicolas Schier <nsc@kernel.org>
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build
The current clang thin-lto build often produces lots of symbols with
suffix. The following is a partial list of such function call symbols:
...
ethnl_module_fw_flash_ntf.llvm.7631589765585346066
__nf_conntrack_alloc.llvm.6438426151906658917
tcp_can_early_drop.llvm.11937612064648250727
tcp_print_conntrack.llvm.11937612064648250727
...
In my particular build with current bpf-next, the number of '*.llvm.<hash>'
function calls is 1212. As the side effect of cross-file inlining,
some static variables may be promoted with '*.llvm.<hash>' as well.
In my same setup, the number of variables with such suffixes is 9.
Such symbols make kernel live patching difficult since
- a minor code change will change the hash and then the '*.llvm.<hash>'
symbol becomes another one with a different hash. Sometimes, maybe
the suffix is gone.
- a previous source-level symbol may become a one with suffix after live
patching code.
In [1], Song Liu suggested to reduce the number of '*.llvm.<hash>' functions
to make live patch easier. In respond of this, I implemented this
in llvm ([2]). The same thin-lto build with [2] only has two symbols with
suffix:
m_stop.llvm.14460341347352036579
m_next.llvm.14460341347352036579
This should make live patch much easier.
To support suffix symbol reduction, two lld flags are necessary to enable
this feature in kernel:
- Flag '--lto-whole-program-visibility' is needed as it ensures that all
non-assembly files are available in the same thin-lto lld, which is true
for kernel.
- Flag '-mllvm -always-rename-promoted-locals=false' is needed to enable
suffix reduction. Currently in llvm [1], only process mode is supported.
There is another distributed mode (across different processes or even
different machines) which is not supported yet ([2]). The kernel uses
process mode so it should work.
The assembly files may have some global functions/data which may potentially
conflict with thin-lto global symbols after the above two flags. But such assembly
global symbols are limited and tend to be uniquely named for its context.
Hence the conflict with globals in non-assembly codes is rare. If indeed the
conflict happens, we can rename either of them to avoid conflicts.
Nathan Chancellor suggested the following under thin-lto:
KBUILD_LDFLAGS += $(call ld-option,--lto-whole-program-visibility -mllvm -always-rename-promoted-locals=false)
The '-mllvm -always-rename-promoted-locals=false' flag is only available for llvm23.
So for llvm22 or earlier, the above KBUILD_LDFLAGS will ignore those two flags.
For llvm23 and later, two flags will be added to KBUILD_LDFLAGS.
[1] https://lpc.events/event/19/contributions/2212
[2] https://github.com/llvm/llvm-project/pull/178587
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org> # build
Link: https://patch.msgid.link/20260307050250.3767489-1-yonghong.song@linux.dev
Signed-off-by: Nicolas Schier <nsc@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux
Pull Rust fixes from Miguel Ojeda:
"Toolchain and infrastructure:
- Remap paths to avoid absolute ones starting with the upcoming Rust
1.95.0 release. This improves build reproducibility, avoids leaking
the exact path and avoids having the same path appear in two forms
The approach here avoids remapping debug information as well, in
order to avoid breaking tools that used the paths to access source
files, which was the previous attempt that needed to be reverted
- Allow 'unused_features' lint for the upcoming Rust 1.96.0 release.
While well-intentioned, we do not benefit much from the new lint
- Emit dependency information into '$(depfile)' directly to avoid a
temporary '.d' file (it was an old approach)
'kernel' crate:
- 'str' module: fix warning under '!CONFIG_BLOCK' by making
'NullTerminatedFormatter' public
- 'cpufreq' module: suppress false positive Clippy warning
'pin-init' crate:
- Remove '#[disable_initialized_field_access]' attribute which was
unsound. This means removing the support for structs with unaligned
fields (through the 'repr(packed)' attribute), for now
And document the load-bearing fact of field accessors (i.e. that
they are required for soundness)
- Replace shadowed return token by 'unsafe'-to-create token in order
to remain sound in the face of the likely upcoming Type Alias Impl
Trait (TAIT) and the next trait solver in upstream Rust"
* tag 'rust-fixes-7.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
rust: kbuild: allow `unused_features`
rust: cpufreq: suppress clippy::double_parens in Policy doctest
rust: pin-init: replace shadowed return token by `unsafe`-to-create token
rust: pin-init: internal: init: document load-bearing fact of field accessors
rust: pin-init: internal: init: remove `#[disable_initialized_field_access]`
rust: build: remap path to avoid absolute path
rust: kbuild: emit dep-info into $(depfile) directly
rust: str: make NullTerminatedFormatter public
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Starting with the upcoming Rust 1.96.0 (to be released 2026-05-28),
`rustc` introduces the new lint `unused_features` [1], which warns [2]:
warning: feature `used_with_arg` is declared but not used
--> <crate attribute>:1:93
|
1 | #![feature(asm_const,asm_goto,arbitrary_self_types,lint_reasons,offset_of_nested,raw_ref_op,used_with_arg)]
| ^^^^^^^^^^^^^
|
= note: `#[warn(unused_features)]` (part of `#[warn(unused)]`) on by default
The original goal of using `-Zcrate-attr` automatically was that there
is a consistent set of features enabled and managed globally for all
Rust kernel code (modulo exceptions like the `rust/` crated).
While we could require crates to enable features manually (even if we
still keep the `-Zallow-features=` list, i.e. removing the `-Zcrate-attr`
list), it is not really worth making all developers worry about it just
for a new lint.
The features are expected to eventually become stable anyway (most already
did), and thus having to remove features in every file that may use them
is not worth it either.
Thus just allow the new lint globally.
The lint actually existed for a long time, which is why `rustc` does
not complain about an unknown lint in the stable versions we support,
but it was "disabled" years ago [3], and now it was made to work again.
For extra context, the new implementation of the lint has already been
improved to avoid linting about features that became stable thanks to
Benno's report and the ensuing discussion [4] [5], but while that helps,
it is still the case that we may have features enabled that are not used
for one reason or another in a particular crate.
Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs).
Link: https://github.com/rust-lang/rust/pull/152164 [1]
Link: https://github.com/Rust-for-Linux/pin-init/pull/114 [2]
Link: https://github.com/rust-lang/rust/issues/44232 [3]
Link: https://github.com/rust-lang/rust/issues/153523 [4]
Link: https://github.com/rust-lang/rust/pull/153610 [5]
Reviewed-by: Benno Lossin <lossin@kernel.org>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260312111014.74198-1-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
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Clang recently added '-fms-anonymous-structs' [1] to specifically enable
the Microsoft tagged anonymous structure / union extension, for which
the kernel added '-fms-extensions' in commit c4781dc3d1cf ("Kbuild:
enable -fms-extensions"). Switch to this more narrow option if it is
available, which would have helped avoid the issue addressed by
commit a6773e6932cb ("jfs: Rename _inline to avoid conflict with clang's
'-fms-extensions'"). GCC has talked about adding a similar flag [2] as
well but potentially naming it differently.
Move the selection of the flag to Kconfig to make it easier to use
cc-option (as CC_FLAGS_DIALECT may be used in arch Makefiles, which may
be too early for cc-option in Kbuild) and customize based on compiler
flag names.
Link: https://github.com/llvm/llvm-project/commit/c391efe6fb67329d8e2fd231692cc6b0ea902956 [1]
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123623 [2]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Reviewed-by: Kees Cook <kees@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Link: https://patch.msgid.link/20260223-fms-anonymous-structs-v1-2-8ee406d3c36c@kernel.org
Signed-off-by: Nicolas Schier <nsc@kernel.org>
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Introduce CC_FLAGS_DIALECT to make it easier to update the various
places in the tree that rely on the GNU C standard and Microsoft
extensions flags atomically. All remaining uses of '-std=gnu11' and
'-fms-extensions' are in the tools directory (which has its own build
system) and other standalone Makefiles. This will allow the kernel to
use a narrower option to enable the Microsoft anonymous tagged structure
extension in a simpler manner. Place the CC_FLAGS_DIALECT block after
the configuration include (so that a future change can move the
selection of the flag to Kconfig) but before the
arch/$(SRCARCH)/Makefile include (so that CC_FLAGS_DIALECT is available
for use in those Makefiles).
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Helge Deller <deller@gmx.de> # parisc
Link: https://patch.msgid.link/20260223-fms-anonymous-structs-v1-1-8ee406d3c36c@kernel.org
Signed-off-by: Nicolas Schier <nsc@kernel.org>
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The makefile tries to delete a file named ".builtin-dtb.S" but the file
created by scripts/Makefile.vmlinux is actually called ".builtin-dtbs.S".
Fixes: 654102df2ac2a ("kbuild: add generic support for built-in boot DTBs")
Cc: stable@vger.kernel.org
Signed-off-by: Charles Mirabile <cmirabil@redhat.com>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://patch.msgid.link/20260308044338.181403-1-cmirabil@redhat.com
[nathan: Small commit message adjustments]
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
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