kernel/linux.git/include/asm-generic, branch v6.18.21

kbuild: Split .modinfo out from ELF_DETAILS

2026-03-12T11:09:44+00:00

commit 8678591b47469fe16357234efef9b260317b8be4 upstream. Commit 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped") added .modinfo to ELF_DETAILS while removing it from COMMON_DISCARDS, as it was needed in vmlinux.unstripped and ELF_DETAILS was present in all architecture specific vmlinux linker scripts. While this shuffle is fine for vmlinux, ELF_DETAILS and COMMON_DISCARDS may be used by other linker scripts, such as the s390 and x86 compressed boot images, which may not expect to have a .modinfo section. In certain circumstances, this could result in a bootloader failing to load the compressed kernel [1]. Commit ddc6cbef3ef1 ("s390/boot/vmlinux.lds.S: Ensure bzImage ends with SecureBoot trailer") recently addressed this for the s390 bzImage but the same bug remains for arm, parisc, and x86. The presence of .modinfo in the x86 bzImage was the root cause of the issue worked around with commit d50f21091358 ("kbuild: align modinfo section for Secureboot Authenticode EDK2 compat"). misc.c in arch/x86/boot/compressed includes lib/decompress_unzstd.c, which in turn includes lib/xxhash.c and its MODULE_LICENSE / MODULE_DESCRIPTION macros due to the STATIC definition. Split .modinfo out from ELF_DETAILS into its own macro and handle it in all vmlinux linker scripts. Discard .modinfo in the places where it was previously being discarded from being in COMMON_DISCARDS, as it has never been necessary in those uses. Cc: stable@vger.kernel.org Fixes: 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped") Reported-by: Ed W Closes: https://lore.kernel.org/587f25e0-a80e-46a5-9f01-87cb40cfa377@wildgooses.com/ [1] Tested-by: Ed W # x86_64 Link: https://patch.msgid.link/20260225-separate-modinfo-from-elf-details-v1-1-387ced6baf4b@kernel.org Signed-off-by: Nathan Chancellor Signed-off-by: Greg Kroah-Hartman

audit: add missing syscalls to read class

2026-03-04T12:19:29+00:00

[ Upstream commit bcb90a2834c7393c26df9609b889a3097b7700cd ] The "at" variant of getxattr() and listxattr() are missing from the audit read class. Calling getxattrat() or listxattrat() on a file to read its extended attributes will bypass audit rules such as: -w /tmp/test -p rwa -k test_rwa The current patch adds missing syscalls to the audit read class. Signed-off-by: Jeffrey Bencteux Signed-off-by: Paul Moore Signed-off-by: Sasha Levin

audit: add fchmodat2() to change attributes class

2026-03-04T12:19:28+00:00

[ Upstream commit 4f493a6079b588cf1f04ce5ed6cdad45ab0d53dc ] fchmodat2(), introduced in version 6.6 is currently not in the change attribute class of audit. Calling fchmodat2() to change a file attribute in the same fashion than chmod() or fchmodat() will bypass audit rules such as: -w /tmp/test -p rwa -k test_rwa The current patch adds fchmodat2() to the change attributes class. Signed-off-by: Jeffrey Bencteux Signed-off-by: Paul Moore Signed-off-by: Sasha Levin

rqspinlock: Fix TAS fallback lock entry creation

2026-02-26T22:59:04+00:00

[ Upstream commit 82f3b142c99cf44c7b1e70b7720169c646b9760f ] The TAS fallback can be invoked directly when queued spin locks are disabled, and through the slow path when paravirt is enabled for queued spin locks. In the latter case, the res_spin_lock macro will attempt the fast path and already hold the entry when entering the slow path. This will lead to creation of extraneous entries that are not released, which may cause false positives for deadlock detection. Fix this by always preceding invocation of the TAS fallback in every case with the grabbing of the held lock entry, and add a comment to make note of this. Fixes: c9102a68c070 ("rqspinlock: Add a test-and-set fallback") Reported-by: Amery Hung Signed-off-by: Kumar Kartikeya Dwivedi Tested-by: Amery Hung Link: https://lore.kernel.org/r/20260122115911.3668985-1-memxor@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables using mmu_gather

2026-02-19T15:31:34+00:00

commit 8ce720d5bd91e9dc16db3604aa4b1bf76770a9a1 upstream. As reported, ever since commit 1013af4f585f ("mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race") we can end up in some situations where we perform so many IPI broadcasts when unsharing hugetlb PMD page tables that it severely regresses some workloads. In particular, when we fork()+exit(), or when we munmap() a large area backed by many shared PMD tables, we perform one IPI broadcast per unshared PMD table. There are two optimizations to be had: (1) When we process (unshare) multiple such PMD tables, such as during exit(), it is sufficient to send a single IPI broadcast (as long as we respect locking rules) instead of one per PMD table. Locking prevents that any of these PMD tables could get reused before we drop the lock. (2) When we are not the last sharer (> 2 users including us), there is no need to send the IPI broadcast. The shared PMD tables cannot become exclusive (fully unshared) before an IPI will be broadcasted by the last sharer. Concurrent GUP-fast could walk into a PMD table just before we unshared it. It could then succeed in grabbing a page from the shared page table even after munmap() etc succeeded (and supressed an IPI). But there is not difference compared to GUP-fast just sleeping for a while after grabbing the page and re-enabling IRQs. Most importantly, GUP-fast will never walk into page tables that are no-longer shared, because the last sharer will issue an IPI broadcast. (if ever required, checking whether the PUD changed in GUP-fast after grabbing the page like we do in the PTE case could handle this) So let's rework PMD sharing TLB flushing + IPI sync to use the mmu_gather infrastructure so we can implement these optimizations and demystify the code at least a bit. Extend the mmu_gather infrastructure to be able to deal with our special hugetlb PMD table sharing implementation. To make initialization of the mmu_gather easier when working on a single VMA (in particular, when dealing with hugetlb), provide tlb_gather_mmu_vma(). We'll consolidate the handling for (full) unsharing of PMD tables in tlb_unshare_pmd_ptdesc() and tlb_flush_unshared_tables(), and track in "struct mmu_gather" whether we had (full) unsharing of PMD tables. Because locking is very special (concurrent unsharing+reuse must be prevented), we disallow deferring flushing to tlb_finish_mmu() and instead require an explicit earlier call to tlb_flush_unshared_tables(). From hugetlb code, we call huge_pmd_unshare_flush() where we make sure that the expected lock protecting us from concurrent unsharing+reuse is still held. Check with a VM_WARN_ON_ONCE() in tlb_finish_mmu() that tlb_flush_unshared_tables() was properly called earlier. Document it all properly. Notes about tlb_remove_table_sync_one() interaction with unsharing: There are two fairly tricky things: (1) tlb_remove_table_sync_one() is a NOP on architectures without CONFIG_MMU_GATHER_RCU_TABLE_FREE. Here, the assumption is that the previous TLB flush would send an IPI to all relevant CPUs. Careful: some architectures like x86 only send IPIs to all relevant CPUs when tlb->freed_tables is set. The relevant architectures should be selecting MMU_GATHER_RCU_TABLE_FREE, but x86 might not do that in stable kernels and it might have been problematic before this patch. Also, the arch flushing behavior (independent of IPIs) is different when tlb->freed_tables is set. Do we have to enlighten them to also take care of tlb->unshared_tables? So far we didn't care, so hopefully we are fine. Of course, we could be setting tlb->freed_tables as well, but that might then unnecessarily flush too much, because the semantics of tlb->freed_tables are a bit fuzzy. This patch changes nothing in this regard. (2) tlb_remove_table_sync_one() is not a NOP on architectures with CONFIG_MMU_GATHER_RCU_TABLE_FREE that actually don't need a sync. Take x86 as an example: in the common case (!pv, !X86_FEATURE_INVLPGB) we still issue IPIs during TLB flushes and don't actually need the second tlb_remove_table_sync_one(). This optimized can be implemented on top of this, by checking e.g., in tlb_remove_table_sync_one() whether we really need IPIs. But as described in (1), it really must honor tlb->freed_tables then to send IPIs to all relevant CPUs. Notes on TLB flushing changes: (1) Flushing for non-shared PMD tables We're converting from flush_hugetlb_tlb_range() to tlb_remove_huge_tlb_entry(). Given that we properly initialize the MMU gather in tlb_gather_mmu_vma() to be hugetlb aware, similar to __unmap_hugepage_range(), that should be fine. (2) Flushing for shared PMD tables We're converting from various things (flush_hugetlb_tlb_range(), tlb_flush_pmd_range(), flush_tlb_range()) to tlb_flush_pmd_range(). tlb_flush_pmd_range() achieves the same that tlb_remove_huge_tlb_entry() would achieve in these scenarios. Note that tlb_remove_huge_tlb_entry() also calls __tlb_remove_tlb_entry(), however that is only implemented on powerpc, which does not support PMD table sharing. Similar to (1), tlb_gather_mmu_vma() should make sure that TLB flushing keeps on working as expected. Further, note that the ptdesc_pmd_pts_dec() in huge_pmd_share() is not a concern, as we are holding the i_mmap_lock the whole time, preventing concurrent unsharing. That ptdesc_pmd_pts_dec() usage will be removed separately as a cleanup later. There are plenty more cleanups to be had, but they have to wait until this is fixed. [david@kernel.org: fix kerneldoc] Link: https://lkml.kernel.org/r/f223dd74-331c-412d-93fc-69e360a5006c@kernel.org Link: https://lkml.kernel.org/r/20251223214037.580860-5-david@kernel.org Fixes: 1013af4f585f ("mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race") Signed-off-by: David Hildenbrand (Red Hat) Reported-by: "Uschakow, Stanislav" Closes: https://lore.kernel.org/all/4d3878531c76479d9f8ca9789dc6485d@amazon.de/ Tested-by: Laurence Oberman Acked-by: Harry Yoo Reviewed-by: Lorenzo Stoakes Cc: Lance Yang Cc: Liu Shixin Cc: Oscar Salvador Cc: Rik van Riel Cc: Signed-off-by: Andrew Morton Signed-off-by: David Hildenbrand (Arm) Signed-off-by: Greg Kroah-Hartman

mm: actually mark kernel page table pages

2026-01-23T10:21:35+00:00

commit 977870522af34359b461060597ee3a86f27450d6 upstream. Now that the API is in place, mark kernel page table pages just after they are allocated. Unmark them just before they are freed. Note: Unconditionally clearing the 'kernel' marking (via ptdesc_clear_kernel()) would be functionally identical to what is here. But having the if() makes it logically clear that this function can be used for kernel and non-kernel page tables. Link: https://lkml.kernel.org/r/20251022082635.2462433-4-baolu.lu@linux.intel.com Signed-off-by: Dave Hansen Signed-off-by: Lu Baolu Reviewed-by: Jason Gunthorpe Reviewed-by: Kevin Tian Acked-by: David Hildenbrand Acked-by: Mike Rapoport (Microsoft) Cc: Alistair Popple Cc: Andy Lutomirski Cc: Borislav Betkov Cc: Ingo Molnar Cc: Jann Horn Cc: Jean-Philippe Brucker Cc: Joerg Roedel Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Peter Zijlstra Cc: Robin Murohy Cc: Thomas Gleinxer Cc: "Uladzislau Rezki (Sony)" Cc: Vasant Hegde Cc: Vinicius Costa Gomes Cc: Vlastimil Babka Cc: Will Deacon Cc: Yi Lai Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

rqspinlock: Enclose lock/unlock within lock entry acquisitions

2025-12-18T13:03:28+00:00

[ Upstream commit beb7021a6003d9c6a463fffca0d6311efb8e0e66 ] Ritesh reported that timeouts occurred frequently for rqspinlock despite reentrancy on the same lock on the same CPU in [0]. This patch closes one of the races leading to this behavior, and reduces the frequency of timeouts. We currently have a tiny window between the fast-path cmpxchg and the grabbing of the lock entry where an NMI could land, attempt the same lock that was just acquired, and end up timing out. This is not ideal. Instead, move the lock entry acquisition from the fast path to before the cmpxchg, and remove the grabbing of the lock entry in the slow path, assuming it was already taken by the fast path. The TAS fallback is invoked directly without being preceded by the typical fast path, therefore we must continue to grab the deadlock detection entry in that case. Case on lock leading to missed AA: cmpxchg lock A ... rqspinlock acquisition of A ... timeout grab_held_lock_entry(A) There is a similar case when unlocking the lock. If the NMI lands between the WRITE_ONCE and smp_store_release, it is possible that we end up in a situation where the NMI fails to diagnose the AA condition, leading to a timeout. Case on unlock leading to missed AA: WRITE_ONCE(rqh->locks[rqh->cnt - 1], NULL) ... rqspinlock acquisition of A ... timeout smp_store_release(A->locked, 0) The patch changes the order on unlock to smp_store_release() succeeded by WRITE_ONCE() of NULL. This avoids the missed AA detection described above, but may lead to a false positive if the NMI lands between these two statements, which is acceptable (and preferred over a timeout). The original intention of the reverse order on unlock was to prevent the following possible misdiagnosis of an ABBA scenario: grab entry A lock A grab entry B lock B unlock B smp_store_release(B->locked, 0) grab entry B lock B grab entry A lock A ! WRITE_ONCE(rqh->locks[rqh->cnt - 1], NULL) If the store release were is after the WRITE_ONCE, the other CPU would not observe B in the table of the CPU unlocking the lock B. However, since the threads are obviously participating in an ABBA deadlock, it is no longer appealing to use the order above since it may lead to a 250 ms timeout due to missed AA detection. [0]: https://lore.kernel.org/bpf/CAH6OuBTjG+N=+GGwcpOUbeDN563oz4iVcU3rbse68egp9wj9_A@mail.gmail.com Fixes: 0d80e7f951be ("rqspinlock: Choose trylock fallback for NMI waiters") Reported-by: Ritesh Oedayrajsingh Varma Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20251128232802.1031906-2-memxor@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin

mshv: Fix deposit memory in MSHV_ROOT_HVCALL

2025-12-18T13:03:01+00:00

[ Upstream commit 4cc1aa469cd6b714adc958547a4866247bfd60a9 ] When the MSHV_ROOT_HVCALL ioctl is executing a hypercall, and gets HV_STATUS_INSUFFICIENT_MEMORY, it deposits memory and then returns -EAGAIN to userspace. The expectation is that the VMM will retry. However, some VMM code in the wild doesn't do this and simply fails. Rather than force the VMM to retry, change the ioctl to deposit memory on demand and immediately retry the hypercall as is done with all the other hypercall helper functions. In addition to making the ioctl easier to use, removing the need for multiple syscalls improves performance. There is a complication: unlike the other hypercall helper functions, in MSHV_ROOT_HVCALL the input is opaque to the kernel. This is problematic for rep hypercalls, because the next part of the input list can't be copied on each loop after depositing pages (this was the original reason for returning -EAGAIN in this case). Introduce hv_do_rep_hypercall_ex(), which adds a 'rep_start' parameter. This solves the issue, allowing the deposit loop in MSHV_ROOT_HVCALL to restart a rep hypercall after depositing pages partway through. Fixes: 621191d709b1 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs") Signed-off-by: Nuno Das Neves Reviewed-by: Michael Kelley Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

kbuild: align modinfo section for Secureboot Authenticode EDK2 compat

2025-10-27T23:21:24+00:00

Previously linker scripts would always generate vmlinuz that has sections aligned. And thus padded (correct Authenticode calculation) and unpadded calculation would be same. As in https://github.com/rhboot/pesign userspace tool would produce the same authenticode digest for both of the following commands: pesign --padding --hash --in ./arch/x86_64/boot/bzImage pesign --nopadding --hash --in ./arch/x86_64/boot/bzImage The commit 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped") added .modinfo section of variable length. Depending on kernel configuration it may or may not be aligned. All userspace signing tooling correctly pads such section to calculation spec compliant authenticode digest. However, if bzImage is not further processed and is attempted to be loaded directly by EDK2 firmware, it calculates unpadded Authenticode digest and fails to correct accept/reject such kernel builds even when propoer Authenticode values are enrolled in db/dbx. One can say EDK2 requires aligned/padded kernels in Secureboot. Thus add ALIGN(8) to the .modinfo section, to esure kernels irrespective of modinfo contents can be loaded by all existing EDK2 firmware builds. Fixes: 3e86e4d74c04 ("kbuild: keep .modinfo section in vmlinux.unstripped") Cc: stable@vger.kernel.org Signed-off-by: Dimitri John Ledkov Link: https://patch.msgid.link/20251026202100.679989-1-dimitri.ledkov@surgut.co.uk Signed-off-by: Nathan Chancellor

Merge tag 'hyperv-next-signed-20251006' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

2025-10-07T15:40:15+00:00

Pull hyperv updates from Wei Liu: - Unify guest entry code for KVM and MSHV (Sean Christopherson) - Switch Hyper-V MSI domain to use msi_create_parent_irq_domain() (Nam Cao) - Add CONFIG_HYPERV_VMBUS and limit the semantics of CONFIG_HYPERV (Mukesh Rathor) - Add kexec/kdump support on Azure CVMs (Vitaly Kuznetsov) - Deprecate hyperv_fb in favor of Hyper-V DRM driver (Prasanna Kumar T S M) - Miscellaneous enhancements, fixes and cleanups (Abhishek Tiwari, Alok Tiwari, Nuno Das Neves, Wei Liu, Roman Kisel, Michael Kelley) * tag 'hyperv-next-signed-20251006' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: hyperv: Remove the spurious null directive line MAINTAINERS: Mark hyperv_fb driver Obsolete fbdev/hyperv_fb: deprecate this in favor of Hyper-V DRM driver Drivers: hv: Make CONFIG_HYPERV bool Drivers: hv: Add CONFIG_HYPERV_VMBUS option Drivers: hv: vmbus: Fix typos in vmbus_drv.c Drivers: hv: vmbus: Fix sysfs output format for ring buffer index Drivers: hv: vmbus: Clean up sscanf format specifier in target_cpu_store() x86/hyperv: Switch to msi_create_parent_irq_domain() mshv: Use common "entry virt" APIs to do work in root before running guest entry: Rename "kvm" entry code assets to "virt" to genericize APIs entry/kvm: KVM: Move KVM details related to signal/-EINTR into KVM proper mshv: Handle NEED_RESCHED_LAZY before transferring to guest x86/hyperv: Add kexec/kdump support on Azure CVMs Drivers: hv: Simplify data structures for VMBus channel close message Drivers: hv: util: Cosmetic changes for hv_utils_transport.c mshv: Add support for a new parent partition configuration clocksource: hyper-v: Skip unnecessary checks for the root partition hyperv: Add missing field to hv_output_map_device_interrupt