kernel/linux.git/arch/x86/Makefile, branch v6.12.91

rust: kbuild: support `-Cjump-tables=n` for Rust 1.93.0

2026-02-06T15:55:49+00:00

commit 789521b4717fd6bd85164ba5c131f621a79c9736 upstream. Rust 1.93.0 (expected 2026-01-22) is stabilizing `-Zno-jump-tables` [1][2] as `-Cjump-tables=n` [3]. Without this change, one would eventually see: RUSTC L rust/core.o error: unknown unstable option: `no-jump-tables` Thus support the upcoming version. Link: https://github.com/rust-lang/rust/issues/116592 [1] Link: https://github.com/rust-lang/rust/pull/105812 [2] Link: https://github.com/rust-lang/rust/pull/145974 [3] Reviewed-by: Alice Ryhl Reviewed-by: Trevor Gross Acked-by: Nicolas Schier Link: https://patch.msgid.link/20251101094011.1024534-1-ojeda@kernel.org Signed-off-by: Miguel Ojeda Signed-off-by: Alyssa Ross Signed-off-by: Greg Kroah-Hartman

x86/stackprotector: Work around strict Clang TLS symbol requirements

2024-11-08T12:16:00+00:00

GCC and Clang both implement stack protector support based on Thread Local Storage (TLS) variables, and this is used in the kernel to implement per-task stack cookies, by copying a task's stack cookie into a per-CPU variable every time it is scheduled in. Both now also implement -mstack-protector-guard-symbol=, which permits the TLS variable to be specified directly. This is useful because it will allow to move away from using a fixed offset of 40 bytes into the per-CPU area on x86_64, which requires a lot of special handling in the per-CPU code and the runtime relocation code. However, while GCC is rather lax in its implementation of this command line option, Clang actually requires that the provided symbol name refers to a TLS variable (i.e., one declared with __thread), although it also permits the variable to be undeclared entirely, in which case it will use an implicit declaration of the right type. The upshot of this is that Clang will emit the correct references to the stack cookie variable in most cases, e.g., 10d: 64 a1 00 00 00 00 mov %fs:0x0,%eax 10f: R_386_32 __stack_chk_guard However, if a non-TLS definition of the symbol in question is visible in the same compilation unit (which amounts to the whole of vmlinux if LTO is enabled), it will drop the per-CPU prefix and emit a load from a bogus address. Work around this by using a symbol name that never occurs in C code, and emit it as an alias in the linker script. Fixes: 3fb0fdb3bbe7 ("x86/stackprotector/32: Make the canary into a regular percpu variable") Signed-off-by: Ard Biesheuvel Signed-off-by: Brian Gerst Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Cc: stable@vger.kernel.org Link: https://github.com/ClangBuiltLinux/linux/issues/1854 Link: https://lore.kernel.org/r/20241105155801.1779119-2-brgerst@gmail.com

rust: cfi: add support for CFI_CLANG with Rust

2024-09-16T15:29:58+00:00

Make it possible to use the Control Flow Integrity (CFI) sanitizer when Rust is enabled. Enabling CFI with Rust requires that CFI is configured to normalize integer types so that all integer types of the same size and signedness are compatible under CFI. Rust and C use the same LLVM backend for code generation, so Rust KCFI is compatible with the KCFI used in the kernel for C. In the case of FineIBT, CFI also depends on -Zpatchable-function-entry for rewriting the function prologue, so we set that flag for Rust as well. The flag for FineIBT requires rustc 1.80.0 or later, so include a Kconfig requirement for that. Enabling Rust will select CFI_ICALL_NORMALIZE_INTEGERS because the flag is required to use Rust with CFI. Using select rather than `depends on` avoids the case where Rust is not visible in menuconfig due to CFI_ICALL_NORMALIZE_INTEGERS not being enabled. One disadvantage of select is that RUST must `depends on` all of the things that CFI_ICALL_NORMALIZE_INTEGERS depends on to avoid invalid configurations. Alice has been using KCFI on her phone for several months, so it is reasonably well tested on arm64. Signed-off-by: Matthew Maurer Co-developed-by: Alice Ryhl Signed-off-by: Alice Ryhl Reviewed-by: Sami Tolvanen Tested-by: Gatlin Newhouse Acked-by: Kees Cook Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20240801-kcfi-v2-2-c93caed3d121@google.com [ Replaced `!FINEIBT` requirement with `!CALL_PADDING` to prevent a build error on older Rust compilers. Fixed typo. - Miguel ] Signed-off-by: Miguel Ojeda

x86/rust: support MITIGATION_RETHUNK

2024-08-18T21:34:37+00:00

The Rust compiler added support for `-Zfunction-return=thunk-extern` [1] in 1.76.0 [2], i.e. the equivalent of `-mfunction-return=thunk-extern`. Thus add support for `MITIGATION_RETHUNK`. Without this, `objtool` would warn if enabled for Rust and already warns under IBT builds, e.g.: samples/rust/rust_print.o: warning: objtool: _R...init+0xa5c: 'naked' return found in RETHUNK build Link: https://github.com/rust-lang/rust/issues/116853 [1] Link: https://github.com/rust-lang/rust/pull/116892 [2] Reviewed-by: Gary Guo Tested-by: Alice Ryhl Tested-by: Benno Lossin Reviewed-by: Thomas Gleixner Link: https://github.com/Rust-for-Linux/linux/issues/945 Link: https://lore.kernel.org/r/20240725183325.122827-4-ojeda@kernel.org Signed-off-by: Miguel Ojeda

x86/rust: support MITIGATION_RETPOLINE

2024-08-18T21:34:37+00:00

Support `MITIGATION_RETPOLINE` by enabling the target features that Clang does. The existing target feature being enabled was a leftover from our old `rust` branch, and it is not enough: the target feature `retpoline-external-thunk` only implies `retpoline-indirect-calls`, but not `retpoline-indirect-branches` (see LLVM's `X86.td`), unlike Clang's flag of the same name `-mretpoline-external-thunk` which does imply both (see Clang's `lib/Driver/ToolChains/Arch/X86.cpp`). Without this, `objtool` would complain if enabled for Rust, e.g.: rust/core.o: warning: objtool: _R...escape_default+0x13: indirect jump found in RETPOLINE build In addition, change the comment to note that LLVM is the one disabling jump tables when retpoline is enabled, thus we do not need to use `-Zno-jump-tables` for Rust here -- see commit c58f2166ab39 ("Introduce the "retpoline" x86 mitigation technique ...") [1]: The goal is simple: avoid generating code which contains an indirect branch that could have its prediction poisoned by an attacker. In many cases, the compiler can simply use directed conditional branches and a small search tree. LLVM already has support for lowering switches in this way and the first step of this patch is to disable jump-table lowering of switches and introduce a pass to rewrite explicit indirectbr sequences into a switch over integers. As well as a live example at [2]. These should be eventually enabled via `-Ctarget-feature` when `rustc` starts recognizing them (or via a new dedicated flag) [3]. Cc: Daniel Borkmann Link: https://github.com/llvm/llvm-project/commit/c58f2166ab3987f37cb0d7815b561bff5a20a69a [1] Link: https://godbolt.org/z/G4YPr58qG [2] Link: https://github.com/rust-lang/rust/issues/116852 [3] Reviewed-by: Gary Guo Tested-by: Alice Ryhl Tested-by: Benno Lossin Link: https://github.com/Rust-for-Linux/linux/issues/945 Link: https://lore.kernel.org/r/20240725183325.122827-3-ojeda@kernel.org Signed-off-by: Miguel Ojeda

Merge tag 'mm-nonmm-stable-2024-05-22-17-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-05-23T01:59:29+00:00

Pull more non-mm updates from Andrew Morton: - A series ("kbuild: enable more warnings by default") from Arnd Bergmann which enables a number of additional build-time warnings. We fixed all the fallout which we could find, there may still be a few stragglers. - Samuel Holland has developed the series "Unified cross-architecture kernel-mode FPU API". This does a lot of consolidation of per-architecture kernel-mode FPU usage and enables the use of newer AMD GPUs on RISC-V. - Tao Su has fixed some selftests build warnings in the series "Selftests: Fix compilation warnings due to missing _GNU_SOURCE definition". - This pull also includes a nilfs2 fixup from Ryusuke Konishi. * tag 'mm-nonmm-stable-2024-05-22-17-30' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (23 commits) nilfs2: make block erasure safe in nilfs_finish_roll_forward() selftests/harness: use 1024 in place of LINE_MAX Revert "selftests/harness: remove use of LINE_MAX" selftests/fpu: allow building on other architectures selftests/fpu: move FP code to a separate translation unit drm/amd/display: use ARCH_HAS_KERNEL_FPU_SUPPORT drm/amd/display: only use hard-float, not altivec on powerpc riscv: add support for kernel-mode FPU x86: implement ARCH_HAS_KERNEL_FPU_SUPPORT powerpc: implement ARCH_HAS_KERNEL_FPU_SUPPORT LoongArch: implement ARCH_HAS_KERNEL_FPU_SUPPORT lib/raid6: use CC_FLAGS_FPU for NEON CFLAGS arm64: crypto: use CC_FLAGS_FPU for NEON CFLAGS arm64: implement ARCH_HAS_KERNEL_FPU_SUPPORT ARM: crypto: use CC_FLAGS_FPU for NEON CFLAGS ARM: implement ARCH_HAS_KERNEL_FPU_SUPPORT arch: add ARCH_HAS_KERNEL_FPU_SUPPORT x86/fpu: fix asm/fpu/types.h include guard kbuild: enable -Wcast-function-type-strict unconditionally kbuild: enable -Wformat-truncation on clang ...

x86: implement ARCH_HAS_KERNEL_FPU_SUPPORT

2024-05-19T21:36:19+00:00

x86 already provides kernel_fpu_begin() and kernel_fpu_end(), but in a different header. Add a wrapper header, and export the CFLAGS adjustments as found in lib/Makefile. Link: https://lkml.kernel.org/r/20240329072441.591471-11-samuel.holland@sifive.com Signed-off-by: Samuel Holland Reviewed-by: Christoph Hellwig Acked-by: Christian König Cc: Alex Deucher Cc: Borislav Petkov (AMD) Cc: Catalin Marinas Cc: Dave Hansen Cc: Huacai Chen Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Masahiro Yamada Cc: Michael Ellerman Cc: Nathan Chancellor Cc: Nicolas Schier Cc: Palmer Dabbelt Cc: Russell King Cc: Thomas Gleixner Cc: WANG Xuerui Cc: Will Deacon Signed-off-by: Andrew Morton

arch: Select fbdev helpers with CONFIG_VIDEO

2024-05-03T15:07:50+00:00

Various Kconfig options selected the per-architecture helpers for fbdev. But none of the contained code depends on fbdev. Standardize on CONFIG_VIDEO, which will allow to add more general helpers for video functionality. CONFIG_VIDEO protects each architecture's video/ directory. This allows for the use of more fine-grained control for each directory's files, such as the use of CONFIG_STI_CORE on parisc. v2: - sparc: rebased onto Makefile changes Signed-off-by: Thomas Zimmermann Reviewed-by: Sam Ravnborg Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: "David S. Miller" Cc: Andreas Larsson Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: x86@kernel.org Cc: "H. Peter Anvin" Signed-off-by: Arnd Bergmann

x86/build: Use obj-y to descend into arch/x86/virt/

2024-03-30T09:41:49+00:00

Commit c33621b4c5ad ("x86/virt/tdx: Wire up basic SEAMCALL functions") introduced a new instance of core-y instead of the standardized obj-y syntax. X86 Makefiles descend into subdirectories of arch/x86/virt inconsistently; into arch/x86/virt/ via core-y defined in arch/x86/Makefile, but into arch/x86/virt/svm/ via obj-y defined in arch/x86/Kbuild. This is problematic when you build a single object in parallel because multiple threads attempt to build the same file. $ make -j$(nproc) arch/x86/virt/vmx/tdx/seamcall.o [ snip ] AS arch/x86/virt/vmx/tdx/seamcall.o AS arch/x86/virt/vmx/tdx/seamcall.o fixdep: error opening file: arch/x86/virt/vmx/tdx/.seamcall.o.d: No such file or directory make[4]: *** [scripts/Makefile.build:362: arch/x86/virt/vmx/tdx/seamcall.o] Error 2 Use the obj-y syntax, as it works correctly. Signed-off-by: Masahiro Yamada Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20240330060554.18524-1-masahiroy@kernel.org

Merge tag 'mm-nonmm-stable-2024-03-14-09-36' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-03-15T01:03:09+00:00

Pull non-MM updates from Andrew Morton: - Kuan-Wei Chiu has developed the well-named series "lib min_heap: Min heap optimizations". - Kuan-Wei Chiu has also sped up the library sorting code in the series "lib/sort: Optimize the number of swaps and comparisons". - Alexey Gladkov has added the ability for code running within an IPC namespace to alter its IPC and MQ limits. The series is "Allow to change ipc/mq sysctls inside ipc namespace". - Geert Uytterhoeven has contributed some dhrystone maintenance work in the series "lib: dhry: miscellaneous cleanups". - Ryusuke Konishi continues nilfs2 maintenance work in the series "nilfs2: eliminate kmap and kmap_atomic calls" "nilfs2: fix kernel bug at submit_bh_wbc()" - Nathan Chancellor has updated our build tools requirements in the series "Bump the minimum supported version of LLVM to 13.0.1". - Muhammad Usama Anjum continues with the selftests maintenance work in the series "selftests/mm: Improve run_vmtests.sh". - Oleg Nesterov has done some maintenance work against the signal code in the series "get_signal: minor cleanups and fix". Plus the usual shower of singleton patches in various parts of the tree. Please see the individual changelogs for details. * tag 'mm-nonmm-stable-2024-03-14-09-36' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (77 commits) nilfs2: prevent kernel bug at submit_bh_wbc() nilfs2: fix failure to detect DAT corruption in btree and direct mappings ocfs2: enable ocfs2_listxattr for special files ocfs2: remove SLAB_MEM_SPREAD flag usage assoc_array: fix the return value in assoc_array_insert_mid_shortcut() buildid: use kmap_local_page() watchdog/core: remove sysctl handlers from public header nilfs2: use div64_ul() instead of do_div() mul_u64_u64_div_u64: increase precision by conditionally swapping a and b kexec: copy only happens before uchunk goes to zero get_signal: don't initialize ksig->info if SIGNAL_GROUP_EXIT/group_exec_task get_signal: hide_si_addr_tag_bits: fix the usage of uninitialized ksig get_signal: don't abuse ksig->info.si_signo and ksig->sig const_structs.checkpatch: add device_type Normalise "name (ad@dr)" MODULE_AUTHORs to "name " dyndbg: replace kstrdup() + strchr() with kstrdup_and_replace() list: leverage list_is_head() for list_entry_is_head() nilfs2: MAINTAINERS: drop unreachable project mirror site smp: make __smp_processor_id() 0-argument macro fat: fix uninitialized field in nostale filehandles ...