kernel.git/arch/um/include, branch linux-6.15.y

um: Re-evaluate thread flags repeatedly

2025-08-20T16:36:05Z

[ Upstream commit b9e2f2246eb2b5617d53af7b5e4e1b8c916f26a8 ] The thread flags may change during their processing. For example a task_work can queue a new signal to be sent. This signal should be delivered before returning to usespace again. Evaluate the flags repeatedly similar to other architectures. Signed-off-by: Thomas Weißschuh Reviewed-by: Nam Cao Link: https://patch.msgid.link/20250704-uml-thread_flags-v1-1-0e293fd8d627@linutronix.de Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin

um: Add cmpxchg8b_emu and checksum functions to asm-prototypes.h

2025-07-06T09:04:06Z

[ Upstream commit 674d03f6bd6b0f8327f1a4920ff5893557facfbd ] With CONFIG_GENDWARFKSYMS, um builds fail due to missing prototypes in asm/asm-prototypes.h. Add declarations for cmpxchg8b_emu and the exported checksum functions, including csum_partial_copy_generic as it's also exported. Cc: Masahiro Yamada Cc: linux-kbuild@vger.kernel.org Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202503251216.lE4t9Ikj-lkp@intel.com/ Signed-off-by: Sami Tolvanen Link: https://patch.msgid.link/20250326190500.847236-2-samitolvanen@google.com Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin

um: fix _nofault accesses

2025-05-05T08:06:51Z

Nathan reported [1] that when built with clang, the um kernel crashes pretty much immediately. This turned out to be an issue with the inline assembly I had added, when clang used %rax/%eax for both operands. Reorder it so current->thread.segv_continue is written first, and then the lifetime of _faulted won't have overlap with the lifetime of segv_continue. In the email thread Benjamin also pointed out that current->mm is only NULL for true kernel tasks, but we could do this for a userspace task, so the current->thread.segv_continue logic must be lifted out of the mm==NULL check. Finally, while looking at this, put a barrier() so the NULL assignment to thread.segv_continue cannot be reorder before the possibly faulting operation. Reported-by: Nathan Chancellor Closes: https://lore.kernel.org/r/20250402221254.GA384@ax162 [1] Fixes: d1d7f01f7cd3 ("um: mark rodata read-only and implement _nofault accesses") Tested-by: Nathan Chancellor Signed-off-by: Johannes Berg

Merge tag 'mm-stable-2025-04-02-22-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-04-03T18:10:00Z

Pull more MM updates from Andrew Morton: - The series "mm: fixes for fallouts from mem_init() cleanup" from Mike Rapoport fixes a couple of issues with the just-merged "arch, mm: reduce code duplication in mem_init()" series - The series "MAINTAINERS: add my isub-entries to MM part." from Mike Rapoport does some maintenance on MAINTAINERS - The series "remove tlb_remove_page_ptdesc()" from Qi Zheng does some cleanup work to the page mapping code - The series "mseal system mappings" from Jeff Xu permits sealing of "system mappings", such as vdso, vvar, vvar_vclock, vectors (arm compat-mode), sigpage (arm compat-mode) - Plus the usual shower of singleton patches * tag 'mm-stable-2025-04-02-22-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (31 commits) mseal sysmap: add arch-support txt mseal sysmap: enable s390 selftest: test system mappings are sealed mseal sysmap: update mseal.rst mseal sysmap: uprobe mapping mseal sysmap: enable arm64 mseal sysmap: enable x86-64 mseal sysmap: generic vdso vvar mapping selftests: x86: test_mremap_vdso: skip if vdso is msealed mseal sysmap: kernel config and header change mm: pgtable: remove tlb_remove_page_ptdesc() x86: pgtable: convert to use tlb_remove_ptdesc() riscv: pgtable: unconditionally use tlb_remove_ptdesc() mm: pgtable: convert some architectures to use tlb_remove_ptdesc() mm: pgtable: change pt parameter of tlb_remove_ptdesc() to struct ptdesc* mm: pgtable: make generic tlb_remove_table() use struct ptdesc microblaze/mm: put mm_cmdline_setup() in .init.text section mm/memory_hotplug: fix call folio_test_large with tail page in do_migrate_range MAINTAINERS: mm: add entry for secretmem MAINTAINERS: mm: add entry for numa memblocks and numa emulation ...

Merge tag 'uml-for-linux-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

2025-04-02T19:25:03Z

Pull UML updates from Johannes Berg: - proper nofault accesses and read-only rodata - hostfs fix for host inode number reuse - fixes for host errno handling - various cleanups/small fixes * tag 'uml-for-linux-6.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: um: Rewrite the sigio workaround based on epoll and tgkill um: Prohibit the VM_CLONE flag in run_helper_thread() um: Switch to the pthread-based helper in sigio workaround um: ubd: Switch to the pthread-based helper um: Add pthread-based helper support um: x86: clean up elf specific definitions um: Store full CSGSFS and SS register from mcontext um: virt-pci: Refactor virtio_pcidev into its own module um: work around sched_yield not yielding in time-travel mode um/locking: Remove semicolon from "lock" prefix um: Update min_low_pfn to match changes in uml_reserved um: use str_yes_no() to remove hardcoded "yes" and "no" um: hostfs: avoid issues on inode number reuse by host um: Allocate vdso page pointer statically um: remove copy_from_kernel_nofault_allowed um: mark rodata read-only and implement _nofault accesses um: Pass the correct Rust target and options with gcc

mm: pgtable: convert some architectures to use tlb_remove_ptdesc()

2025-04-01T22:17:13Z

Now, the nine architectures of csky, hexagon, loongarch, m68k, mips, nios2, openrisc, sh and um do not select CONFIG_MMU_GATHER_RCU_TABLE_FREE, and just call pagetable_dtor() + tlb_remove_page_ptdesc() (the wrapper of tlb_remove_page()). This is the same as the implementation of tlb_remove_{ptdesc|table}() under !CONFIG_MMU_GATHER_TABLE_FREE, so convert these architectures to use tlb_remove_ptdesc(). The ultimate goal is to make the architecture only use tlb_remove_ptdesc() or tlb_remove_table() for page table pages. [zhengqi.arch@bytedance.com: v2] Link: https://lkml.kernel.org/r/20250303072603.45423-1-zhengqi.arch@bytedance.com [akpm@linux-foundation.org: remove trailing semi in arch/loongarch/include/asm/pgalloc.h] Link: https://lkml.kernel.org/r/19db3e8673b67bad2f1df1ab37f1c89d99eacfea.1740454179.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng Suggested-by: Peter Zijlstra (Intel) Reviewed-by: Kevin Brodsky Acked-by: Geert Uytterhoeven [m68k] Cc: Alexandre Ghiti Cc: "Aneesh Kumar K.V" Cc: Arnd Bergmann Cc: Dave Hansen Cc: David Hildenbrand Cc: Hugh Dickens Cc: Jann Horn Cc: Matthew Wilcow (Oracle) Cc: "Mike Rapoport (IBM)" Cc: Muchun Song Cc: Nicholas Piggin Cc: Rik van Riel Cc: Vishal Moola (Oracle) Cc: Will Deacon Cc: Yu Zhao Signed-off-by: Andrew Morton

um: Rewrite the sigio workaround based on epoll and tgkill

2025-03-20T08:28:44Z

The existing sigio workaround implementation removes FDs from the poll when events are triggered, requiring users to re-add them via add_sigio_fd() after processing. This introduces a potential race condition between FD removal in write_sigio_thread() and next_poll update in __add_sigio_fd(), and is inefficient due to frequent FD removal and re-addition. Rewrite the implementation based on epoll and tgkill for improved efficiency and reliability. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20250315161910.4082396-2-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg

um: Add pthread-based helper support

2025-03-20T08:26:38Z

Introduce a new set of utility functions that can be used to create pthread-based helpers. Helper threads created in this way will ensure thread safety for errno while sharing the same memory space. Signed-off-by: Tiwei Bie Link: https://patch.msgid.link/20250319135523.97050-2-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg

um: x86: clean up elf specific definitions

2025-03-18T13:48:31Z

The file arch/x86/um/asm/module.h is equivalent to the definition of asm-generic. Thus this commit cleans up to use it. Signed-off-by: Hajime Tazaki Link: https://patch.msgid.link/2d70a0ed79ee0a0bef80ad4790063f4833dd9bed.1737348399.git.thehajime@gmail.com Signed-off-by: Johannes Berg

um: work around sched_yield not yielding in time-travel mode

2025-03-18T10:06:20Z

sched_yield by a userspace may not actually cause scheduling in time-travel mode as no time has passed. In the case seen it appears to be a badly implemented userspace spinlock in ASAN. Unfortunately, with time-travel it causes an extreme slowdown or even deadlock depending on the kernel configuration (CONFIG_UML_MAX_USERSPACE_ITERATIONS). Work around it by accounting time to the process whenever it executes a sched_yield syscall. Signed-off-by: Benjamin Berg Link: https://patch.msgid.link/20250314130815.226872-1-benjamin@sipsolutions.net Signed-off-by: Johannes Berg