kernel/linux.git/arch/um/include/asm, branch v7.0-rc7

treewide: provide a generic clear_user_page() variant

2026-01-21T03:24:39+00:00

Patch series "mm: folio_zero_user: clear page ranges", v11. This series adds clearing of contiguous page ranges for hugepages. The series improves on the current discontiguous clearing approach in two ways: - clear pages in a contiguous fashion. - use batched clearing via clear_pages() wherever exposed. The first is useful because it allows us to make much better use of hardware prefetchers. The second, enables advertising the real extent to the processor. Where specific instructions support it (ex. string instructions on x86; "mops" on arm64 etc), a processor can optimize based on this because, instead of seeing a sequence of 8-byte stores, or a sequence of 4KB pages, it sees a larger unit being operated on. For instance, AMD Zen uarchs (for extents larger than LLC-size) switch to a mode where they start eliding cacheline allocation. This is helpful not just because it results in higher bandwidth, but also because now the cache is not evicting useful cachelines and replacing them with zeroes. Demand faulting a 64GB region shows performance improvement: $ perf bench mem mmap -p $pg-sz -f demand -s 64GB -l 5 baseline +series (GBps +- %stdev) (GBps +- %stdev) pg-sz=2MB 11.76 +- 1.10% 25.34 +- 1.18% [*] +115.47% preempt=* pg-sz=1GB 24.85 +- 2.41% 39.22 +- 2.32% + 57.82% preempt=none|voluntary pg-sz=1GB (similar) 52.73 +- 0.20% [#] +112.19% preempt=full|lazy [*] This improvement is because switching to sequential clearing allows the hardware prefetchers to do a much better job. [#] For pg-sz=1GB a large part of the improvement is because of the cacheline elision mentioned above. preempt=full|lazy improves upon that because, not needing explicit invocations of cond_resched() to ensure reasonable preemption latency, it can clear the full extent as a single unit. In comparison the maximum extent used for preempt=none|voluntary is PROCESS_PAGES_NON_PREEMPT_BATCH (32MB). When provided the full extent the processor forgoes allocating cachelines on this path almost entirely. (The hope is that eventually, in the fullness of time, the lazy preemption model will be able to do the same job that none or voluntary models are used for, allowing us to do away with cond_resched().) Raghavendra also tested previous version of the series on AMD Genoa and sees similar improvement [1] with preempt=lazy. $ perf bench mem map -p $page-size -f populate -s 64GB -l 10 base patched change pg-sz=2MB 12.731939 GB/sec 26.304263 GB/sec 106.6% pg-sz=1GB 26.232423 GB/sec 61.174836 GB/sec 133.2% This patch (of 8): Let's drop all variants that effectively map to clear_page() and provide it in a generic variant instead. We'll use the macro clear_user_page to indicate whether an architecture provides it's own variant. Also, clear_user_page() is only called from the generic variant of clear_user_highpage(), so define it only if the architecture does not provide a clear_user_highpage(). And, for simplicity define it in linux/highmem.h. Note that for parisc, clear_page() and clear_user_page() map to clear_page_asm(), so we can just get rid of the custom clear_user_page() implementation. There is a clear_user_page_asm() function on parisc, that seems to be unused. Not sure what's up with that. Link: https://lkml.kernel.org/r/20260107072009.1615991-1-ankur.a.arora@oracle.com Link: https://lkml.kernel.org/r/20260107072009.1615991-2-ankur.a.arora@oracle.com Signed-off-by: David Hildenbrand Co-developed-by: Ankur Arora Signed-off-by: Ankur Arora Cc: Andy Lutomirski Cc: Ankur Arora Cc: "Borislav Petkov (AMD)" Cc: Boris Ostrovsky Cc: David Hildenbrand Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Konrad Rzessutek Wilk Cc: Lance Yang Cc: "Liam R. Howlett" Cc: Li Zhe Cc: Lorenzo Stoakes Cc: Mateusz Guzik Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Peter Zijlstra Cc: Raghavendra K T Cc: Suren Baghdasaryan Cc: Thomas Gleixner Cc: Vlastimil Babka Signed-off-by: Andrew Morton

Merge tag 'objtool-urgent-2025-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2025-12-06T19:56:51+00:00

Pull objtool fixes from Ingo Molnar: "Address various objtool scalability bugs/inefficiencies exposed by allmodconfig builds, plus improve the quality of alternatives instructions generated code and disassembly" * tag 'objtool-urgent-2025-12-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: objtool: Simplify .annotate_insn code generation output some more objtool: Add more robust signal error handling, detect and warn about stack overflows objtool: Remove newlines and tabs from annotation macros objtool: Consolidate annotation macros x86/asm: Remove ANNOTATE_DATA_SPECIAL usage x86/alternative: Remove ANNOTATE_DATA_SPECIAL usage objtool: Fix stack overflow in validate_branch()

x86/asm: Remove ANNOTATE_DATA_SPECIAL usage

2025-12-03T15:53:19+00:00

Instead of manually annotating each __ex_table entry, just make the section mergeable and store the entry size in the ELF section header. Either way works for objtool create_fake_symbols(), this way produces cleaner code generation. Signed-off-by: Josh Poimboeuf Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://patch.msgid.link/b858cb7891c1ba0080e22a9c32595e6c302435e2.1764694625.git.jpoimboe@kernel.org

um: Disable KASAN_INLINE when STATIC_LINK is selected

2025-12-01T10:54:50+00:00

um doesn't support KASAN_INLINE together with STATIC_LINK. Instead of failing the build, disable KASAN_INLINE when STATIC_LINK is selected. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202511290451.x9GZVJ1l-lkp@intel.com/ Fixes: 1e338f4d99e6 ("kasan: introduce ARCH_DEFER_KASAN and unify static key across modes") Signed-off-by: Christophe Leroy (CS GROUP) Link: https://patch.msgid.link/2620ab0bbba640b6237c50b9c0dca1c7d1142f5d.1764410067.git.chleroy@kernel.org Signed-off-by: Johannes Berg

um: Remove __access_ok_vsyscall()

2025-11-06T12:02:34+00:00

FIXADDR_USER_START and FIXADDR_USER_END are now always zero. Signed-off-by: Thomas Weißschuh Link: https://patch.msgid.link/20251028-uml-remove-32bit-pseudo-vdso-v1-8-e930063eff5f@weissschuh.net Signed-off-by: Johannes Berg

um: Remove redundant range check from __access_ok_vsyscall()

2025-11-06T12:02:33+00:00

The only caller __access_ok() is already doing the same check through __addr_range_nowrap(). Remove the redundant check. Signed-off-by: Thomas Weißschuh Link: https://patch.msgid.link/20251028-uml-remove-32bit-pseudo-vdso-v1-7-e930063eff5f@weissschuh.net Signed-off-by: Johannes Berg

x86/um: Drop gate area handling

2025-11-06T12:02:33+00:00

With the removal of the vDSO passthrough from the host, FIXADDR_USER_START is always 0 and the gate area setup code is dead. Remove it. Signed-off-by: Thomas Weißschuh Link: https://patch.msgid.link/20251028-uml-remove-32bit-pseudo-vdso-v1-5-e930063eff5f@weissschuh.net Signed-off-by: Johannes Berg

um: Avoid circular dependency on asm-offsets in pgtable.h

2025-10-28T10:40:49+00:00

Recent changes have added an include of as-layout.h to pgtable.h. However this introduces a circular dependency during asm-offsets generation as as-layout.h depends on asm-offsets and pgtable.h is an input for asm-offsets. Building from a clean state results in the following error: CC arch/um/kernel/asm-offsets.s In file included from arch/um/include/asm/pgtable.h:48, from include/linux/pgtable.h:6, from include/linux/mm.h:31, from include/linux/pid_namespace.h:7, from include/linux/ptrace.h:10, from include/linux/audit.h:13, from arch/um/kernel/asm-offsets.c:8: arch/um/include/shared/as-layout.h:9:10: fatal error: generated/asm-offsets.h: No such file or directory 9 | #include | ^~~~~~~~~~~~~~~~~~~~~~~~~ compilation terminated. make[4]: *** [scripts/Makefile.build:182: arch/um/kernel/asm-offsets.s] Error 1 As the inclusion of as-layout.h in pgtable.h is not yet needed while asm-offsets are generated, break the dependency here. Fixes: a7f7dbae94a5 ("um: Remove file-based iomem emulation support") Signed-off-by: Thomas Weißschuh Reviewed-by: Tiwei Bie Link: https://patch.msgid.link/20251028-uml-offsets-circular-v1-1-601c363cfaaa@weissschuh.net Signed-off-by: Johannes Berg

um: Add initial SMP support

2025-10-27T15:41:15+00:00

Add initial symmetric multi-processing (SMP) support to UML. With this support enabled, users can tell UML to start multiple virtual processors, each represented as a separate host thread. In UML, kthreads and normal threads (when running in kernel mode) can be scheduled and executed simultaneously on different virtual processors. However, the userspace code of normal threads still runs within their respective single-threaded stubs. That is, SMP support is currently available both within the kernel and across different processes, but still remains limited within threads of the same process in userspace. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20251027001815.1666872-6-tiwei.bie@linux.dev Signed-off-by: Johannes Berg

um: Turn signals_* into thread-local variables

2025-10-27T15:41:15+00:00

Turn signals_enabled, signals_pending and signals_active into thread-local variables. This enables us to control and track signals independently on each CPU thread. This is a preparation for adding SMP support. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20251027001815.1666872-3-tiwei.bie@linux.dev Signed-off-by: Johannes Berg