kernel/linux.git/scripts/Makefile.build, branch v7.3-rc1

kbuild: rust: keep Rust objects out of Clang LTO with inline helpers

2026-08-23T19:27:17+00:00

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit `objtool` errors such as: vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a: can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd The reason is that in such builds, the Clang invocation that compiles the combined Rust plus helpers bitcode emits LLVM bitcode (again) -- the final code generation happens in the linker's LTO step, which the `-mllvm` trap options passed to Clang do not reach. This, in turn, means that unreachable traps are missing, and the impossible paths do not merely fallthrough to the next symbol, but past the end of their own section, since LTO builds place each function in its own section. Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always emits machine code directly, with the traps in place. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org Signed-off-by: Miguel Ojeda

kbuild: rust: preserve unreachable traps with inline helpers

2026-08-23T19:27:17+00:00

When `CONFIG_RUST_INLINE_HELPERS` is enabled, it is possible to hit `objtool` warnings like: vmlinux.o: warning: objtool: _R..._4cmdq12CommandToGsp4init() falls through to next function _R..._4core5array4iter8IntoIterRShKj3_EEEBa_() `rustc` normally emits traps for unreachable paths. However, under `CONFIG_RUST_INLINE_HELPERS=y`, `rustc` emits LLVM bitcode and Clang performs final code generation after the helper bitcode is linked, but Clang does not trap unreachable IR by default. In turn, this means `objtool` follows compiler-generated impossible Rust `enum` paths through alignment padding into the next function, resulting in fallthrough warnings. Thus pass the LLVM `trap-unreachable` option to the final Clang invocation and suppress traps immediately after `noreturn` calls, which `objtool` already recognizes as dead ends. The combination of both flags makes it match `rustc`'s behavior. Rust 1.85.0 (the minimum supported one) supports LLVM >= 18, and both flags are available in LLVM 18. Assisted-by: LLM Cc: Gary Guo Cc: Boqun Feng Cc: Alice Ryhl Cc: Matthew Maurer Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: stable@vger.kernel.org Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust") Acked-by: Gary Guo Link: https://patch.msgid.link/20260816133233.197500-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda

kbuild: set the initial value of subdir-rustflags-y

2026-08-05T12:57:44+00:00

Initialize subdir-rustflags-y to an empty value to prevent it from being inadvertently affected by an environment variable of the same name. Signed-off-by: Yuntao Wang Link: https://patch.msgid.link/20260718040146.294700-1-yuntao.wang@linux.dev Signed-off-by: Nicolas Schier

kbuild: remove srctree path from CHECK output

2026-07-07T06:08:51+00:00

The build does not put the full kernel path in when building outputs, so do the same when the check is run to make the output more consistent. turn the following: CC arch/riscv/lib/delay.o CHECK /home/ben/linux/arch/riscv/lib/delay.c into: CC arch/riscv/lib/delay.o CHECK arch/riscv/lib/delay.c Signed-off-by: Ben Dooks Acked-by: Nathan Chancellor Link: https://patch.msgid.link/20260622132653.446868-1-ben.dooks@codethink.co.uk [nsc: Fixed typo in subject line] Signed-off-by: Nicolas Schier

rust: zerocopy-derive: enable support in kbuild

2026-06-09T02:13:23+00:00

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

rust: zerocopy: enable support in kbuild

2026-06-09T02:13:22+00:00

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

Merge tag 'driver-core-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core

2026-04-14T02:03:11+00:00

Pull driver core updates from Danilo Krummrich: "debugfs: - Fix NULL pointer dereference in debugfs_create_str() - Fix misplaced EXPORT_SYMBOL_GPL for debugfs_create_str() - Fix soundwire debugfs NULL pointer dereference from uninitialized firmware_file device property: - Make fwnode flags modifications thread safe; widen the field to unsigned long and use set_bit() / clear_bit() based accessors - Document how to check for the property presence devres: - Separate struct devres_node from its "subclasses" (struct devres, struct devres_group); give struct devres_node its own release and free callbacks for per-type dispatch - Introduce struct devres_action for devres actions, avoiding the ARCH_DMA_MINALIGN alignment overhead of struct devres - Export struct devres_node and its init/add/remove/dbginfo primitives for use by Rust Devres - Fix missing node debug info in devm_krealloc() - Use guard(spinlock_irqsave) where applicable; consolidate unlock paths in devres_release_group() driver_override: - Convert PCI, WMI, vdpa, s390/cio, s390/ap, and fsl-mc to the generic driver_override infrastructure, replacing per-bus driver_override strings, sysfs attributes, and match logic; fixes a potential UAF from unsynchronized access to driver_override in bus match() callbacks - Simplify __device_set_driver_override() logic kernfs: - Send IN_DELETE_SELF and IN_IGNORED inotify events on kernfs file and directory removal - Add corresponding selftests for memcg platform: - Allow attaching software nodes when creating platform devices via a new 'swnode' field in struct platform_device_info - Add kerneldoc for struct platform_device_info software node: - Move software node initialization from postcore_initcall() to driver_init(), making it available early in the boot process - Move kernel_kobj initialization (ksysfs_init) earlier to support the above - Remove software_node_exit(); dead code in a built-in unit SoC: - Introduce of_machine_read_compatible() and of_machine_read_model() OF helpers and export soc_attr_read_machine() to replace direct accesses to of_root from SoC drivers; also enables CONFIG_COMPILE_TEST coverage for these drivers sysfs: - Constify attribute group array pointers to 'const struct attribute_group *const *' in sysfs functions, device_add_groups() / device_remove_groups(), and struct class Rust: - Devres: - Embed struct devres_node directly in Devres instead of going through devm_add_action(), avoiding the extra allocation and the unnecessary ARCH_DMA_MINALIGN alignment - I/O: - Turn IoCapable from a marker trait into a functional trait carrying the raw I/O accessor implementation (io_read / io_write), providing working defaults for the per-type Io methods - Add RelaxedMmio wrapper type, making relaxed accessors usable in code generic over the Io trait - Remove overloaded per-type Io methods and per-backend macros from Mmio and PCI ConfigSpace - I/O (Register): - Add IoLoc trait and generic read/write/update methods to the Io trait, making I/O operations parameterizable by typed locations - Add register! macro for defining hardware register types with typed bitfield accessors backed by Bounded values; supports direct, relative, and array register addressing - Add write_reg() / try_write_reg() and LocatedRegister trait - Update PCI sample driver to demonstrate the register! macro Example: ``` register! { /// UART control register. CTRL(u32) @ 0x18 { /// Receiver enable. 19:19 rx_enable => bool; /// Parity configuration. 14:13 parity ?=> Parity; } /// FIFO watermark and counter register. WATER(u32) @ 0x2c { /// Number of datawords in the receive FIFO. 26:24 rx_count; /// RX interrupt threshold. 17:16 rx_water; } } impl WATER { fn rx_above_watermark(&self) -> bool { self.rx_count() > self.rx_water() } } fn init(bar: &pci::Bar) { let water = WATER::zeroed() .with_const_rx_water::<1>(); // > 3 would not compile bar.write_reg(water); let ctrl = CTRL::zeroed() .with_parity(Parity::Even) .with_rx_enable(true); bar.write_reg(ctrl); } fn handle_rx(bar: &pci::Bar) { if bar.read(WATER).rx_above_watermark() { // drain the FIFO } } fn set_parity(bar: &pci::Bar, parity: Parity) { bar.update(CTRL, |r| r.with_parity(parity)); } ``` - IRQ: - Move 'static bounds from where clauses to trait declarations for IRQ handler traits - Misc: - Enable the generic_arg_infer Rust feature - Extend Bounded with shift operations, single-bit bool conversion, and const get() Misc: - Make deferred_probe_timeout default a Kconfig option - Drop auxiliary_dev_pm_ops; the PM core falls back to driver PM callbacks when no bus type PM ops are set - Add conditional guard support for device_lock() - Add ksysfs.c to the DRIVER CORE MAINTAINERS entry - Fix kernel-doc warnings in base.h - Fix stale reference to memory_block_add_nid() in documentation" * tag 'driver-core-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core: (67 commits) bus: fsl-mc: use generic driver_override infrastructure s390/ap: use generic driver_override infrastructure s390/cio: use generic driver_override infrastructure vdpa: use generic driver_override infrastructure platform/wmi: use generic driver_override infrastructure PCI: use generic driver_override infrastructure driver core: make software nodes available earlier software node: remove software_node_exit() kernel: ksysfs: initialize kernel_kobj earlier MAINTAINERS: add ksysfs.c to the DRIVER CORE entry drivers/base/memory: fix stale reference to memory_block_add_nid() device property: Document how to check for the property presence soundwire: debugfs: initialize firmware_file to empty string debugfs: fix placement of EXPORT_SYMBOL_GPL for debugfs_create_str() debugfs: check for NULL pointer in debugfs_create_str() driver core: Make deferred_probe_timeout default a Kconfig option driver core: simplify __device_set_driver_override() clearing logic driver core: auxiliary bus: Drop auxiliary_dev_pm_ops device property: Make modifications of fwnode "flags" thread safe rust: devres: embed struct devres_node directly ...

rust: kbuild: remove `feature(...)`s that are now stable

2026-04-07T08:00:24+00:00

Now that the Rust minimum version is 1.85.0, there is no need to enable certain features that are stable. Thus clean them up. Reviewed-by: Tamir Duberstein Reviewed-by: Gary Guo Link: https://patch.msgid.link/20260405235309.418950-13-ojeda@kernel.org Signed-off-by: Miguel Ojeda

rust: support overriding crate_name

2026-04-03T09:57:35+00:00

Currently you cannot filter out the crate-name argument RUSTFLAGS_REMOVE_stem.o because the Rust filter-out invocation does not include that particular argument. Since --crate-name is an argument that can't be passed multiple times, this means that it's currently not possible to override the crate name. Thus, remove the --crate-name argument for drivers. This allows them to override the crate name using the #![crate_name] annotation. This affects symbol names, but has no effect on the filenames of object files and other things generated by the build, as we always use --emit with a fixed output filename. The --crate-name argument is kept for the crates under rust/ for simplicity and to avoid changing many of them by adding #![crate_name]. The rust analyzer script is updated to use rustc to obtain the crate name of the driver crates, which picks up the right name whether it is configured via #![crate_name] or not. For readability, the logic to invoke 'rustc' is extracted to its own function. Note that the crate name in the python script is not actually that important - the only place where the name actually affects anything is in the 'deps' array which specifies an index and name for each dependency, and determines what that dependency is called in *this* crate. (The same crate may be called different things in each dependency.) Since driver crates are leaf crates, this doesn't apply and the rustc invocation only affects the 'display_name' parameter. Acked-by: Gary Guo Signed-off-by: Alice Ryhl Reviewed-by: Jesung Yang Acked-by: Tamir Duberstein Link: https://patch.msgid.link/20260402-binder-crate-name-v4-1-ec3919b87909@google.com [ Applied Python type hints. - Miguel ] Signed-off-by: Miguel Ojeda

kbuild: rust: provide an option to inline C helpers into Rust

2026-03-30T00:03:52+00:00

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 Signed-off-by: Boqun Feng Co-developed-by: Matthew Maurer Signed-off-by: Matthew Maurer Signed-off-by: Gary Guo Co-developed-by: Alice Ryhl Signed-off-by: Alice Ryhl Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Tested-by: Andreas Hindborg Reviewed-by: Andreas Hindborg 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