kernel/linux.git/include/asm-generic/vmlinux.lds.h, branch v6.6.131

once: fix race by moving DO_ONCE to separate section

2025-10-15T09:57:54+00:00

[ Upstream commit edcc8a38b5ac1a3dbd05e113a38a25b937ebefe5 ] The commit c2c60ea37e5b ("once: use __section(".data.once")") moved DO_ONCE's ___done variable to .data.once section, which conflicts with DO_ONCE_LITE() that also uses the same section. This creates a race condition when clear_warn_once is used: Thread 1 (DO_ONCE) Thread 2 (DO_ONCE) __do_once_start read ___done (false) acquire once_lock execute func __do_once_done write ___done (true) __do_once_start release once_lock // Thread 3 clear_warn_once reset ___done read ___done (false) acquire once_lock execute func schedule once_work __do_once_done once_deferred: OK write ___done (true) static_branch_disable release once_lock schedule once_work once_deferred: BUG_ON(!static_key_enabled) DO_ONCE_LITE() in once_lite.h is used by WARN_ON_ONCE() and other warning macros. Keep its ___done flag in the .data..once section and allow resetting by clear_warn_once, as originally intended. In contrast, DO_ONCE() is used for functions like get_random_once() and relies on its ___done flag for internal synchronization. We should not reset DO_ONCE() by clear_warn_once. Fix it by isolating DO_ONCE's ___done into a separate .data..do_once section, shielding it from clear_warn_once. Fixes: c2c60ea37e5b ("once: use __section(".data.once")") Reported-by: Hulk Robot Signed-off-by: Qi Xi Signed-off-by: Arnd Bergmann Signed-off-by: Sasha Levin

vmlinux.lds: Ensure that const vars with relocations are mapped R/O

2025-03-07T15:45:47+00:00

commit 68f3ea7ee199ef77551e090dfef5a49046ea8443 upstream. In the kernel, there are architectures (x86, arm64) that perform boot-time relocation (for KASLR) without relying on PIE codegen. In this case, all const global objects are emitted into .rodata, including const objects with fields that will be fixed up by the boot-time relocation code. This implies that .rodata (and .text in some cases) need to be writable at boot, but they will usually be mapped read-only as soon as the boot completes. When using PIE codegen, the compiler will emit const global objects into .data.rel.ro rather than .rodata if the object contains fields that need such fixups at boot-time. This permits the linker to annotate such regions as requiring read-write access only at load time, but not at execution time (in user space), while keeping .rodata truly const (in user space, this is important for reducing the CoW footprint of dynamic executables). This distinction does not matter for the kernel, but it does imply that const data will end up in writable memory if the .data.rel.ro sections are not treated in a special way, as they will end up in the writable .data segment by default. So emit .data.rel.ro into the .rodata segment. Cc: stable@vger.kernel.org Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20250221135704.431269-5-ardb+git@google.com Signed-off-by: Josh Poimboeuf Signed-off-by: Greg Kroah-Hartman

Rename .data.once to .data..once to fix resetting WARN*_ONCE

2024-12-09T09:32:59+00:00

[ Upstream commit dbefa1f31a91670c9e7dac9b559625336206466f ] Commit b1fca27d384e ("kernel debug: support resetting WARN*_ONCE") added support for clearing the state of once warnings. However, it is not functional when CONFIG_LD_DEAD_CODE_DATA_ELIMINATION or CONFIG_LTO_CLANG is enabled, because .data.once matches the .data.[0-9a-zA-Z_]* pattern in the DATA_MAIN macro. Commit cb87481ee89d ("kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured") was introduced to suppress the issue for the default CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=n case, providing a minimal fix for stable backporting. We were aware this did not address the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y. The plan was to apply correct fixes and then revert cb87481ee89d. [1] Seven years have passed since then, yet the #ifdef workaround remains in place. Meanwhile, commit b1fca27d384e introduced the .data.once section, and commit dc5723b02e52 ("kbuild: add support for Clang LTO") extended the #ifdef. Using a ".." separator in the section name fixes the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION and CONFIG_LTO_CLANG. [1]: https://lore.kernel.org/linux-kbuild/CAK7LNASck6BfdLnESxXUeECYL26yUDm0cwRZuM4gmaWUkxjL5g@mail.gmail.com/ Fixes: b1fca27d384e ("kernel debug: support resetting WARN*_ONCE") Fixes: dc5723b02e52 ("kbuild: add support for Clang LTO") Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

Rename .data.unlikely to .data..unlikely

2024-12-09T09:32:59+00:00

[ Upstream commit bb43a59944f45e89aa158740b8a16ba8f0b0fa2b ] Commit 7ccaba5314ca ("consolidate WARN_...ONCE() static variables") was intended to collect all .data.unlikely sections into one chunk. However, this has not worked when CONFIG_LD_DEAD_CODE_DATA_ELIMINATION or CONFIG_LTO_CLANG is enabled, because .data.unlikely matches the .data.[0-9a-zA-Z_]* pattern in the DATA_MAIN macro. Commit cb87481ee89d ("kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured") was introduced to suppress the issue for the default CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=n case, providing a minimal fix for stable backporting. We were aware this did not address the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y. The plan was to apply correct fixes and then revert cb87481ee89d. [1] Seven years have passed since then, yet the #ifdef workaround remains in place. Using a ".." separator in the section name fixes the issue for CONFIG_LD_DEAD_CODE_DATA_ELIMINATION and CONFIG_LTO_CLANG. [1]: https://lore.kernel.org/linux-kbuild/CAK7LNASck6BfdLnESxXUeECYL26yUDm0cwRZuM4gmaWUkxjL5g@mail.gmail.com/ Fixes: cb87481ee89d ("kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured") Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

init/modpost: conditionally check section mismatch to __meminit*

2024-12-09T09:32:59+00:00

[ Upstream commit 73db3abdca58c8a014ec4c88cf5ef925cbf63669 ] This reverts commit eb8f689046b8 ("Use separate sections for __dev/ _cpu/__mem code/data"). Check section mismatch to __meminit* only when CONFIG_MEMORY_HOTPLUG=n. With this change, the linker script and modpost become simpler, and we can get rid of the __ref annotations from the memory hotplug code. [sfr@canb.auug.org.au: remove MEM_KEEP from arch/powerpc/kernel/vmlinux.lds.S] Link: https://lkml.kernel.org/r/20240710093213.2aefb25f@canb.auug.org.au Link: https://lkml.kernel.org/r/20240706160511.2331061-2-masahiroy@kernel.org Signed-off-by: Masahiro Yamada Signed-off-by: Stephen Rothwell Reviewed-by: Wei Yang Cc: Stephen Rothwell Signed-off-by: Andrew Morton Stable-dep-of: bb43a59944f4 ("Rename .data.unlikely to .data..unlikely") Signed-off-by: Sasha Levin

vmlinux.lds.h: catch .bss..L* sections into BSS")

2024-08-03T06:53:35+00:00

[ Upstream commit 1a7b7326d587c9a5e8ff067e70d6aaf0333f4bb3 ] Commit 9a427556fb8e ("vmlinux.lds.h: catch compound literals into data and BSS") added catches for .data..L* and .rodata..L* but missed .bss..L* Since commit 5431fdd2c181 ("ptrace: Convert ptrace_attach() to use lock guards") the following appears at build: LD .tmp_vmlinux.kallsyms1 powerpc64-linux-ld: warning: orphan section `.bss..Lubsan_data33' from `kernel/ptrace.o' being placed in section `.bss..Lubsan_data33' NM .tmp_vmlinux.kallsyms1.syms KSYMS .tmp_vmlinux.kallsyms1.S AS .tmp_vmlinux.kallsyms1.S LD .tmp_vmlinux.kallsyms2 powerpc64-linux-ld: warning: orphan section `.bss..Lubsan_data33' from `kernel/ptrace.o' being placed in section `.bss..Lubsan_data33' NM .tmp_vmlinux.kallsyms2.syms KSYMS .tmp_vmlinux.kallsyms2.S AS .tmp_vmlinux.kallsyms2.S LD vmlinux powerpc64-linux-ld: warning: orphan section `.bss..Lubsan_data33' from `kernel/ptrace.o' being placed in section `.bss..Lubsan_data33' Lets add .bss..L* to BSS_MAIN macro to catch those sections into BSS. Fixes: 9a427556fb8e ("vmlinux.lds.h: catch compound literals into data and BSS") Signed-off-by: Christophe Leroy Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202404031349.nmKhyuUG-lkp@intel.com/ Signed-off-by: Arnd Bergmann Signed-off-by: Sasha Levin

linux/init: remove __memexit* annotations

2024-02-23T08:25:03+00:00

commit 6a4e59eeedc3018cb57722eecfcbb49431aeb05f upstream. We have never used __memexit, __memexitdata, or __memexitconst. These were unneeded. Signed-off-by: Masahiro Yamada Acked-by: Arnd Bergmann Signed-off-by: Greg Kroah-Hartman

vmlinux.lds.h: remove unused CPU_KEEP and CPU_DISCARD macros

2023-10-01T05:55:23+00:00

Remove the left-over of commit e24f6628811e ("modpost: remove all traces of cpuinit/cpuexit sections"). Signed-off-by: Masahiro Yamada Acked-by: Paul Gortmaker

vmlinux.lds.h: Remove a reference to no longer used sections .text..refcount

2023-07-11T21:29:43+00:00

Sections .text..refcount were previously used to hold an error path code for fast refcount overflow protection on x86, see commit 7a46ec0e2f48 ("locking/refcounts, x86/asm: Implement fast refcount overflow protection") and commit 564c9cc84e2a ("locking/refcounts, x86/asm: Use unique .text section for refcount exceptions"). The code was replaced and removed in commit fb041bb7c0a9 ("locking/refcount: Consolidate implementations of refcount_t") and no sections .text..refcount are present since then. Remove then a relic referencing these sections from TEXT_TEXT to avoid confusing people, like me. This is a non-functional change. Signed-off-by: Petr Pavlu Link: https://lore.kernel.org/r/20230711125054.9000-1-petr.pavlu@suse.com Signed-off-by: Kees Cook

Merge tag 'riscv-for-linus-6.5-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

2023-07-07T17:07:19+00:00

Pull more RISC-V updates from Palmer Dabbelt: - A bunch of fixes/cleanups from the first part of the merge window, mostly related to ACPI and vector as those were large - Some documentation improvements, mostly related to the new code - The "riscv,isa" DT key is deprecated - Support for link-time dead code elimination - Support for minor fault registration in userfaultd - A handful of cleanups around CMO alternatives * tag 'riscv-for-linus-6.5-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (23 commits) riscv: mm: mark noncoherent_supported as __ro_after_init riscv: mm: mark CBO relate initialization funcs as __init riscv: errata: thead: only set cbom size & noncoherent during boot riscv: Select HAVE_ARCH_USERFAULTFD_MINOR RISC-V: Document the ISA string parsing rules for ACPI risc-v: Fix order of IPI enablement vs RCU startup mm: riscv: fix an unsafe pte read in huge_pte_alloc() dt-bindings: riscv: deprecate riscv,isa RISC-V: drop error print from riscv_hartid_to_cpuid() riscv: Discard vector state on syscalls riscv: move memblock_allow_resize() after linear mapping is ready riscv: Enable ARCH_SUSPEND_POSSIBLE for s2idle riscv: vdso: include vdso/vsyscall.h for vdso_data selftests: Test RISC-V Vector's first-use handler riscv: vector: clear V-reg in the first-use trap riscv: vector: only enable interrupts in the first-use trap RISC-V: Fix up some vector state related build failures RISC-V: Document that V registers are clobbered on syscalls riscv: disable HAVE_LD_DEAD_CODE_DATA_ELIMINATION for LLD riscv: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION ...