kernel/rust/Makefile, branch linux-6.15.y

rust: workaround `rustdoc` target modifiers bug

2025-08-20T16:36:27Z

commit abbf9a44944171ca99c150adad9361a2f517d3b6 upstream. Starting with Rust 1.88.0 (released 2025-06-26), `rustdoc` complains about a target modifier mismatch in configurations where `-Zfixed-x18` is passed: error: mixing `-Zfixed-x18` will cause an ABI mismatch in crate `rust_out` | = help: the `-Zfixed-x18` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely = note: unset `-Zfixed-x18` in this crate is incompatible with `-Zfixed-x18=` in dependency `core` = help: set `-Zfixed-x18=` in this crate or unset `-Zfixed-x18` in `core` = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=fixed-x18` to silence this error The reason is that `rustdoc` was not passing the target modifiers when configuring the session options, and thus it would report a mismatch that did not exist as soon as a target modifier is used in a dependency. We did not notice it in the kernel until now because `-Zfixed-x18` has been a target modifier only since 1.88.0 (and it is the only one we use so far). The issue has been reported upstream [1] and a fix has been submitted [2], including a test similar to the kernel case. [ This is now fixed upstream (thanks Guillaume for the quick review), so it will be fixed in Rust 1.90.0 (expected 2025-09-18). - Miguel ] Meanwhile, conditionally pass `-Cunsafe-allow-abi-mismatch=fixed-x18` to workaround the issue on our side. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Reported-by: Konrad Dybcio Closes: https://lore.kernel.org/rust-for-linux/36cdc798-524f-4910-8b77-d7b9fac08d77@oss.qualcomm.com/ Link: https://github.com/rust-lang/rust/issues/144521 [1] Link: https://github.com/rust-lang/rust/pull/144523 [2] Reviewed-by: Alice Ryhl Link: https://lore.kernel.org/r/20250727092317.2930617-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda Signed-off-by: Greg Kroah-Hartman

rust: kbuild: clean output before running `rustdoc`

2025-08-20T16:36:27Z

commit 252fea131e15aba2cd487119d1a8f546471199e2 upstream. `rustdoc` can get confused when generating documentation into a folder that contains generated files from other `rustdoc` versions. For instance, running something like: rustup default 1.78.0 make LLVM=1 rustdoc rustup default 1.88.0 make LLVM=1 rustdoc may generate errors like: error: couldn't generate documentation: invalid template: last line expected to start with a comment | = note: failed to create or modify "./Documentation/output/rust/rustdoc/src-files.js" Thus just always clean the output folder before generating the documentation -- we are anyway regenerating it every time the `rustdoc` target gets called, at least for the time being. Cc: stable@vger.kernel.org # Needed in 6.12.y and later (Rust is pinned in older LTSs). Reported-by: Daniel Almeida Closes: https://rust-for-linux.zulipchat.com/#narrow/channel/288089/topic/x/near/527201113 Reviewed-by: Tamir Duberstein Link: https://lore.kernel.org/r/20250726133435.2460085-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda Signed-off-by: Greg Kroah-Hartman

rust: use `#[used(compiler)]` to fix build and `modpost` with Rust >= 1.89.0

2025-07-24T06:58:41Z

commit 7498159226772d66f150dd406be462d75964a366 upstream. Starting with Rust 1.89.0 (expected 2025-08-07), the Rust compiler fails to build the `rusttest` target due to undefined references such as: kernel...-cgu.0:(.text....+0x116): undefined reference to `rust_helper_kunit_get_current_test' Moreover, tooling like `modpost` gets confused: WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/gpu/drm/nova/nova.o ERROR: modpost: missing MODULE_LICENSE() in drivers/gpu/nova-core/nova_core.o The reason behind both issues is that the Rust compiler will now [1] treat `#[used]` as `#[used(linker)]` instead of `#[used(compiler)]` for our targets. This means that the retain section flag (`R`, `SHF_GNU_RETAIN`) will be used and that they will be marked as `unique` too, with different IDs. In turn, that means we end up with undefined references that did not get discarded in `rusttest` and that multiple `.modinfo` sections are generated, which confuse tooling like `modpost` because they only expect one. Thus start using `#[used(compiler)]` to keep the previous behavior and to be explicit about what we want. Sadly, it is an unstable feature (`used_with_arg`) [2] -- we will talk to upstream Rust about it. The good news is that it has been available for a long time (Rust >= 1.60) [3]. The changes should also be fine for previous Rust versions, since they behave the same way as before [4]. Alternatively, we could use `#[no_mangle]` or `#[export_name = ...]` since those still behave like `#[used(compiler)]`, but of course it is not really what we want to express, and it requires other changes to avoid symbol conflicts. Cc: David Wood Cc: Wesley Wiser 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/140872 [1] Link: https://github.com/rust-lang/rust/issues/93798 [2] Link: https://github.com/rust-lang/rust/pull/91504 [3] Link: https://godbolt.org/z/sxzWTMfzW [4] Reviewed-by: Alice Ryhl Acked-by: Björn Roy Baron Link: https://lore.kernel.org/r/20250712160103.1244945-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda Signed-off-by: Greg Kroah-Hartman

rust: arm: fix unknown (to Clang) argument '-mno-fdpic'

2025-07-06T09:04:05Z

[ Upstream commit 977c4308ee4270cf46e2c66b37de8e04670daa0c ] Currently rust on arm fails to compile due to '-mno-fdpic'. This flag disables a GCC feature that we don't want for kernel builds, so let's skip it as it doesn't apply to Clang. UPD include/generated/asm-offsets.h CALL scripts/checksyscalls.sh RUSTC L rust/core.o BINDGEN rust/bindings/bindings_generated.rs BINDGEN rust/bindings/bindings_helpers_generated.rs CC rust/helpers/helpers.o Unable to generate bindings: clang diagnosed error: error: unknown argument: '-mno-fdpic' make[2]: *** [rust/Makefile:369: rust/bindings/bindings_helpers_generated.rs] Error 1 make[2]: *** Deleting file 'rust/bindings/bindings_helpers_generated.rs' make[2]: *** Waiting for unfinished jobs.... Unable to generate bindings: clang diagnosed error: error: unknown argument: '-mno-fdpic' make[2]: *** [rust/Makefile:349: rust/bindings/bindings_generated.rs] Error 1 make[2]: *** Deleting file 'rust/bindings/bindings_generated.rs' make[1]: *** [/home/pmos/build/src/linux-next-next-20250521/Makefile:1285: prepare] Error 2 make: *** [Makefile:248: __sub-make] Error 2 [ Naresh provided the draft diff [1]. Ben explained [2]: FDPIC is only relevant with no-MMU targets, and then only for userspace. When configured for the arm-*-uclinuxfdpiceabi target, GCC enables FDPIC by default to facilitate compiling userspace programs. FDPIC is never used for the kernel, and we pass -mno-fdpic when building the kernel to override the default and make sure FDPIC is disabled. and [3]: -mno-fdpic disables a GCC feature that we don't want for kernel builds. clang does not support this feature, so it always behaves as though -mno-fdpic is passed. Therefore, it should be fine to mix the two, at least as far as FDPIC is concerned. [1] https://lore.kernel.org/rust-for-linux/CA+G9fYt4otQK4pHv8pJBW9e28yHSGCDncKquwuJiJ_1ou0pq0w@mail.gmail.com/ [2] https://lore.kernel.org/rust-for-linux/aAKrq2InExQk7f_k@dell-precision-5540/ [3] https://lore.kernel.org/rust-for-linux/aAo_F_UP1Gd4jHlZ@dell-precision-5540/ - Miguel ] Reported-by: Linux Kernel Functional Testing Closes: https://lore.kernel.org/all/CA+G9fYvOanQBYXKSg7C6EU30k8sTRC0JRPJXYu7wWK51w38QUQ@mail.gmail.com/ Suggested-by: Miguel Ojeda Acked-by: Naresh Kamboju Signed-off-by: Rudraksha Gupta Link: https://lore.kernel.org/r/20250522-rust-mno-fdpic-arm-fix-v2-1-a6f691d9c198@gmail.com [ Reworded title. - Miguel ] Signed-off-by: Miguel Ojeda Signed-off-by: Sasha Levin

rust: compile libcore with edition 2024 for 1.87+

2025-06-19T13:41:02Z

commit f4daa80d6be7d3c55ca72a8e560afc4e21f886aa upstream. Rust 1.87 (released on 2025-05-15) compiles core library with edition 2024 instead of 2021 [1]. Ensure that the edition matches libcore's expectation to avoid potential breakage. [ J3m3 reported in Zulip [2] that the `rust-analyzer` target was broken after this patch -- indeed, we need to avoid `core-cfgs` since those are passed to the `rust-analyzer` target. So, instead, I tweaked the patch to create a new `core-edition` variable and explicitly mention the `--edition` flag instead of reusing `core-cfg`s. In addition, pass a new argument using this new variable to `generate_rust_analyzer.py` so that we set the right edition there. By the way, for future reference: the `filter-out` change is needed for Rust < 1.87, since otherwise we would skip the `--edition=2021` we just added, ending up with no edition flag, and thus the compiler would default to the 2015 one. [2] https://rust-for-linux.zulipchat.com/#narrow/channel/291565/topic/x/near/520206547 - Miguel ] 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/138162 [1] Reported-by: est31 Closes: https://github.com/Rust-for-Linux/linux/issues/1163 Signed-off-by: Gary Guo Link: https://lore.kernel.org/r/20250517085600.2857460-1-gary@garyguo.net Signed-off-by: Miguel Ojeda Signed-off-by: Greg Kroah-Hartman

rust: kbuild: Don't export __pfx symbols

2025-04-08T19:44:20Z

With CONFIG_PREFIX_SYMBOLS, objtool adds __pfx prefix symbols to claim the compiler emitted call padding bytes. When CONFIG_X86_KERNEL_IBT is not selected, the symbols are added to individual object files and for Rust objects, they end up being exported, resulting in warnings with CONFIG_GENDWARFKSYMS as the symbols have no debugging information: warning: gendwarfksyms: symbol_print_versions: no information for symbol __pfx_rust_helper_put_task_struct warning: gendwarfksyms: symbol_print_versions: no information for symbol __pfx_rust_helper_task_euid warning: gendwarfksyms: symbol_print_versions: no information for symbol __pfx_rust_helper_readq_relaxed ... Filter out the __pfx prefix from exported symbols similarly to the existing __cfi and __odr_asan prefixes. Signed-off-by: Sami Tolvanen Reviewed-by: Alice Ryhl Cc: stable@vger.kernel.org Fixes: ac61506bf2d1 ("rust: Use gendwarfksyms + extended modversions for CONFIG_MODVERSIONS") Link: https://lore.kernel.org/r/20250318231815.917621-2-samitolvanen@google.com Signed-off-by: Miguel Ojeda

Merge tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2025-04-05T22:46:50Z

Pull Kbuild updates from Masahiro Yamada: - Improve performance in gendwarfksyms - Remove deprecated EXTRA_*FLAGS and KBUILD_ENABLE_EXTRA_GCC_CHECKS - Support CONFIG_HEADERS_INSTALL for ARCH=um - Use more relative paths to sources files for better reproducibility - Support the loong64 Debian architecture - Add Kbuild bash completion - Introduce intermediate vmlinux.unstripped for architectures that need static relocations to be stripped from the final vmlinux - Fix versioning in Debian packages for -rc releases - Treat missing MODULE_DESCRIPTION() as an error - Convert Nios2 Makefiles to use the generic rule for built-in DTB - Add debuginfo support to the RPM package * tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits) kbuild: rpm-pkg: build a debuginfo RPM kconfig: merge_config: use an empty file as initfile nios2: migrate to the generic rule for built-in DTB rust: kbuild: skip `--remap-path-prefix` for `rustdoc` kbuild: pacman-pkg: hardcode module installation path kbuild: deb-pkg: don't set KBUILD_BUILD_VERSION unconditionally modpost: require a MODULE_DESCRIPTION() kbuild: make all file references relative to source root x86: drop unnecessary prefix map configuration kbuild: deb-pkg: add comment about future removal of KDEB_COMPRESS kbuild: Add a help message for "headers" kbuild: deb-pkg: remove "version" variable in mkdebian kbuild: deb-pkg: fix versioning for -rc releases Documentation/kbuild: Fix indentation in modules.rst example x86: Get rid of Makefile.postlink kbuild: Create intermediate vmlinux build with relocations preserved kbuild: Introduce Kconfig symbol for linking vmlinux with relocations kbuild: link-vmlinux.sh: Make output file name configurable kbuild: do not generate .tmp_vmlinux*.map when CONFIG_VMLINUX_MAP=y Revert "kheaders: Ignore silly-rename files" ...

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux

2025-04-03T19:21:44Z

Pull ARM and clkdev updates from Russell King: - Simplify ARM_MMU_KEEP usage - Add Rust support for ARM architecture version 7 - Align IPIs reported in /proc/interrupts - require linker to support KEEP within OVERLAY - add KEEP() for ARM vectors - add __printf() attribute for clkdev functions * tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rmk/linux: ARM: 9445/1: clkdev: Mark some functions with __printf() attribute ARM: 9444/1: add KEEP() keyword to ARM_VECTORS ARM: 9443/1: Require linker to support KEEP within OVERLAY for DCE ARM: 9442/1: smp: Fix IPI alignment in /proc/interrupts ARM: 9441/1: rust: Enable Rust support for ARMv7 ARM: 9439/1: arm32: simplify ARM_MMU_KEEP usage

Merge tag 'loongarch-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson

2025-04-02T19:15:01Z

Pull LoongArch updates from Huacai Chen: - Always select HAVE_VIRT_CPU_ACCOUNTING_GEN - Enable UBSAN (Undefined Behavior Sanitizer) - Increase MAX_IO_PICS up to 8 - Increase ARCH_DMA_MINALIGN up to 16 - Fix and improve BPF JIT - Fix and improve vDSO implementation - Update the default config file - Some bug fixes and other small changes * tag 'loongarch-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson: LoongArch: Update Loongson-3 default config file LoongArch: vDSO: Make use of the t8 register for vgetrandom-chacha LoongArch: vDSO: Remove --hash-style=sysv LoongArch: BPF: Don't override subprog's return value LoongArch: BPF: Use move_addr() for BPF_PSEUDO_FUNC LoongArch: BPF: Fix off-by-one error in build_prologue() LoongArch: Rework the arch_kgdb_breakpoint() implementation LoongArch: Fix device node refcount leak in fdt_cpu_clk_init() LoongArch: Increase ARCH_DMA_MINALIGN up to 16 LoongArch: Increase MAX_IO_PICS up to 8 LoongArch: Fix help text of CMDLINE_EXTEND in Kconfig LoongArch: Enable UBSAN (Undefined Behavior Sanitizer) LoongArch: Always select HAVE_VIRT_CPU_ACCOUNTING_GEN rust: Fix enabling Rust and building with GCC for LoongArch

rust: Fix enabling Rust and building with GCC for LoongArch

2025-03-30T08:30:20Z

This patch fixes a build issue on LoongArch when Rust is enabled and compiled with GCC by explicitly setting the bindgen target and skipping C flags that Clang doesn't support. Cc: stable@vger.kernel.org Acked-by: Miguel Ojeda Signed-off-by: WANG Rui Signed-off-by: Huacai Chen