starfive-tech/linux.git/mm/userfaultfd.c, branch JH7110_VisionFive2_multi_rtos

userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb

2024-02-23T08:24:53+00:00

commit 67695f18d55924b2013534ef3bdc363bc9e14605 upstream. In mfill_atomic_hugetlb(), mmap_changing isn't being checked again if we drop mmap_lock and reacquire it. When the lock is not held, mmap_changing could have been incremented. This is also inconsistent with the behavior in mfill_atomic(). Link: https://lkml.kernel.org/r/20240117223729.1444522-1-lokeshgidra@google.com Fixes: df2cc96e77011 ("userfaultfd: prevent non-cooperative events vs mcopy_atomic races") Signed-off-by: Lokesh Gidra Cc: Andrea Arcangeli Cc: Mike Rapoport Cc: Axel Rasmussen Cc: Brian Geffon Cc: David Hildenbrand Cc: Jann Horn Cc: Kalesh Singh Cc: Matthew Wilcox (Oracle) Cc: Nicolas Geoffray Cc: Peter Xu Cc: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

Merge tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-08-31T19:20:12+00:00

Pull x86 shadow stack support from Dave Hansen: "This is the long awaited x86 shadow stack support, part of Intel's Control-flow Enforcement Technology (CET). CET consists of two related security features: shadow stacks and indirect branch tracking. This series implements just the shadow stack part of this feature, and just for userspace. The main use case for shadow stack is providing protection against return oriented programming attacks. It works by maintaining a secondary (shadow) stack using a special memory type that has protections against modification. When executing a CALL instruction, the processor pushes the return address to both the normal stack and to the special permission shadow stack. Upon RET, the processor pops the shadow stack copy and compares it to the normal stack copy. For more information, refer to the links below for the earlier versions of this patch set" Link: https://lore.kernel.org/lkml/20220130211838.8382-1-rick.p.edgecombe@intel.com/ Link: https://lore.kernel.org/lkml/20230613001108.3040476-1-rick.p.edgecombe@intel.com/ * tag 'x86_shstk_for_6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (47 commits) x86/shstk: Change order of __user in type x86/ibt: Convert IBT selftest to asm x86/shstk: Don't retry vm_munmap() on -EINTR x86/kbuild: Fix Documentation/ reference x86/shstk: Move arch detail comment out of core mm x86/shstk: Add ARCH_SHSTK_STATUS x86/shstk: Add ARCH_SHSTK_UNLOCK x86: Add PTRACE interface for shadow stack selftests/x86: Add shadow stack test x86/cpufeatures: Enable CET CR4 bit for shadow stack x86/shstk: Wire in shadow stack interface x86: Expose thread features in /proc/$PID/status x86/shstk: Support WRSS for userspace x86/shstk: Introduce map_shadow_stack syscall x86/shstk: Check that signal frame is shadow stack mem x86/shstk: Check that SSP is aligned on sigreturn x86/shstk: Handle signals for shadow stack x86/shstk: Introduce routines modifying shstk x86/shstk: Handle thread shadow stack x86/shstk: Add user-mode shadow stack support ...

mm: userfaultfd: support UFFDIO_POISON for hugetlbfs

2023-08-18T17:12:17+00:00

The behavior here is the same as it is for anon/shmem. This is done separately because hugetlb pte marker handling is a bit different. Link: https://lkml.kernel.org/r/20230707215540.2324998-6-axelrasmussen@google.com Signed-off-by: Axel Rasmussen Acked-by: Peter Xu Cc: Al Viro Cc: Brian Geffon Cc: Christian Brauner Cc: David Hildenbrand Cc: Gaosheng Cui Cc: Huang, Ying Cc: Hugh Dickins Cc: James Houghton Cc: Jan Alexander Steffens (heftig) Cc: Jiaqi Yan Cc: Jonathan Corbet Cc: Kefeng Wang Cc: Liam R. Howlett Cc: Miaohe Lin Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Muchun Song Cc: Nadav Amit Cc: Naoya Horiguchi Cc: Ryan Roberts Cc: Shuah Khan Cc: Suleiman Souhlal Cc: Suren Baghdasaryan Cc: T.J. Alumbaugh Cc: Yu Zhao Cc: ZhangPeng Signed-off-by: Andrew Morton

mm: userfaultfd: add new UFFDIO_POISON ioctl: fix

2023-08-18T17:12:17+00:00

Smatch has observed that pte_offset_map_lock() is now allowed to fail, and then ptl should not be unlocked. Use -EAGAIN here like elsewhere. Link: https://lkml.kernel.org/r/bc7bba61-d34f-ad3a-ccf1-c191585ef851@google.com Signed-off-by: Hugh Dickins Reviewed-by: Axel Rasmussen Cc: Dan Carpenter Cc: Peter Xu Signed-off-by: Andrew Morton

mm: userfaultfd: add new UFFDIO_POISON ioctl

2023-08-18T17:12:16+00:00

The basic idea here is to "simulate" memory poisoning for VMs. A VM running on some host might encounter a memory error, after which some page(s) are poisoned (i.e., future accesses SIGBUS). They expect that once poisoned, pages can never become "un-poisoned". So, when we live migrate the VM, we need to preserve the poisoned status of these pages. When live migrating, we try to get the guest running on its new host as quickly as possible. So, we start it running before all memory has been copied, and before we're certain which pages should be poisoned or not. So the basic way to use this new feature is: - On the new host, the guest's memory is registered with userfaultfd, in either MISSING or MINOR mode (doesn't really matter for this purpose). - On any first access, we get a userfaultfd event. At this point we can communicate with the old host to find out if the page was poisoned. - If so, we can respond with a UFFDIO_POISON - this places a swap marker so any future accesses will SIGBUS. Because the pte is now "present", future accesses won't generate more userfaultfd events, they'll just SIGBUS directly. UFFDIO_POISON does not handle unmapping previously-present PTEs. This isn't needed, because during live migration we want to intercept all accesses with userfaultfd (not just writes, so WP mode isn't useful for this). So whether minor or missing mode is being used (or both), the PTE won't be present in any case, so handling that case isn't needed. Similarly, UFFDIO_POISON won't replace existing PTE markers. This might be okay to do, but it seems to be safer to just refuse to overwrite any existing entry (like a UFFD_WP PTE marker). Link: https://lkml.kernel.org/r/20230707215540.2324998-5-axelrasmussen@google.com Signed-off-by: Axel Rasmussen Acked-by: Peter Xu Cc: Al Viro Cc: Brian Geffon Cc: Christian Brauner Cc: David Hildenbrand Cc: Gaosheng Cui Cc: Huang, Ying Cc: Hugh Dickins Cc: James Houghton Cc: Jan Alexander Steffens (heftig) Cc: Jiaqi Yan Cc: Jonathan Corbet Cc: Kefeng Wang Cc: Liam R. Howlett Cc: Miaohe Lin Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Muchun Song Cc: Nadav Amit Cc: Naoya Horiguchi Cc: Ryan Roberts Cc: Shuah Khan Cc: Suleiman Souhlal Cc: Suren Baghdasaryan Cc: T.J. Alumbaugh Cc: Yu Zhao Cc: ZhangPeng Signed-off-by: Andrew Morton

mm: userfaultfd: extract file size check out into a helper

2023-08-18T17:12:16+00:00

This code is already duplicated twice, and UFFDIO_POISON will do the same check a third time. So, it's worth extracting into a helper to save repetitive lines of code. Link: https://lkml.kernel.org/r/20230707215540.2324998-4-axelrasmussen@google.com Signed-off-by: Axel Rasmussen Reviewed-by: Peter Xu Cc: Al Viro Cc: Brian Geffon Cc: Christian Brauner Cc: David Hildenbrand Cc: Gaosheng Cui Cc: Huang, Ying Cc: Hugh Dickins Cc: James Houghton Cc: Jan Alexander Steffens (heftig) Cc: Jiaqi Yan Cc: Jonathan Corbet Cc: Kefeng Wang Cc: Liam R. Howlett Cc: Miaohe Lin Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Muchun Song Cc: Nadav Amit Cc: Naoya Horiguchi Cc: Ryan Roberts Cc: Shuah Khan Cc: Suleiman Souhlal Cc: Suren Baghdasaryan Cc: T.J. Alumbaugh Cc: Yu Zhao Cc: ZhangPeng Signed-off-by: Andrew Morton

mm: Make pte_mkwrite() take a VMA

2023-07-11T21:12:15+00:00

The x86 Shadow stack feature includes a new type of memory called shadow stack. This shadow stack memory has some unusual properties, which requires some core mm changes to function properly. One of these unusual properties is that shadow stack memory is writable, but only in limited ways. These limits are applied via a specific PTE bit combination. Nevertheless, the memory is writable, and core mm code will need to apply the writable permissions in the typical paths that call pte_mkwrite(). Future patches will make pte_mkwrite() take a VMA, so that the x86 implementation of it can know whether to create regular writable or shadow stack mappings. But there are a couple of challenges to this. Modifying the signatures of each arch pte_mkwrite() implementation would be error prone because some are generated with macros and would need to be re-implemented. Also, some pte_mkwrite() callers operate on kernel memory without a VMA. So this can be done in a three step process. First pte_mkwrite() can be renamed to pte_mkwrite_novma() in each arch, with a generic pte_mkwrite() added that just calls pte_mkwrite_novma(). Next callers without a VMA can be moved to pte_mkwrite_novma(). And lastly, pte_mkwrite() and all callers can be changed to take/pass a VMA. Previous work pte_mkwrite() renamed pte_mkwrite_novma() and converted callers that don't have a VMA were to use pte_mkwrite_novma(). So now change pte_mkwrite() to take a VMA and change the remaining callers to pass a VMA. Apply the same changes for pmd_mkwrite(). No functional change. Suggested-by: David Hildenbrand Signed-off-by: Rick Edgecombe Signed-off-by: Dave Hansen Reviewed-by: Mike Rapoport (IBM) Acked-by: David Hildenbrand Link: https://lore.kernel.org/all/20230613001108.3040476-4-rick.p.edgecombe%40intel.com

mm: ptep_get() conversion

2023-06-19T23:19:25+00:00

Convert all instances of direct pte_t* dereferencing to instead use ptep_get() helper. This means that by default, the accesses change from a C dereference to a READ_ONCE(). This is technically the correct thing to do since where pgtables are modified by HW (for access/dirty) they are volatile and therefore we should always ensure READ_ONCE() semantics. But more importantly, by always using the helper, it can be overridden by the architecture to fully encapsulate the contents of the pte. Arch code is deliberately not converted, as the arch code knows best. It is intended that arch code (arm64) will override the default with its own implementation that can (e.g.) hide certain bits from the core code, or determine young/dirty status by mixing in state from another source. Conversion was done using Coccinelle: ---- // $ make coccicheck \ // COCCI=ptepget.cocci \ // SPFLAGS="--include-headers" \ // MODE=patch virtual patch @ depends on patch @ pte_t *v; @@ - *v + ptep_get(v) ---- Then reviewed and hand-edited to avoid multiple unnecessary calls to ptep_get(), instead opting to store the result of a single call in a variable, where it is correct to do so. This aims to negate any cost of READ_ONCE() and will benefit arch-overrides that may be more complex. Included is a fix for an issue in an earlier version of this patch that was pointed out by kernel test robot. The issue arose because config MMU=n elides definition of the ptep helper functions, including ptep_get(). HUGETLB_PAGE=n configs still define a simple huge_ptep_clear_flush() for linking purposes, which dereferences the ptep. So when both configs are disabled, this caused a build error because ptep_get() is not defined. Fix by continuing to do a direct dereference when MMU=n. This is safe because for this config the arch code cannot be trying to virtualize the ptes because none of the ptep helpers are defined. Link: https://lkml.kernel.org/r/20230612151545.3317766-4-ryan.roberts@arm.com Reported-by: kernel test robot Link: https://lore.kernel.org/oe-kbuild-all/202305120142.yXsNEo6H-lkp@intel.com/ Signed-off-by: Ryan Roberts Cc: Adrian Hunter Cc: Alexander Potapenko Cc: Alexander Shishkin Cc: Alex Williamson Cc: Al Viro Cc: Andrey Konovalov Cc: Andrey Ryabinin Cc: Christian Brauner Cc: Christoph Hellwig Cc: Daniel Vetter Cc: Dave Airlie Cc: Dimitri Sivanich Cc: Dmitry Vyukov Cc: Ian Rogers Cc: Jason Gunthorpe Cc: Jérôme Glisse Cc: Jiri Olsa Cc: Johannes Weiner Cc: Kirill A. Shutemov Cc: Lorenzo Stoakes Cc: Mark Rutland Cc: Matthew Wilcox Cc: Miaohe Lin Cc: Michal Hocko Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Muchun Song Cc: Namhyung Kim Cc: Naoya Horiguchi Cc: Oleksandr Tyshchenko Cc: Pavel Tatashin Cc: Roman Gushchin Cc: SeongJae Park Cc: Shakeel Butt Cc: Uladzislau Rezki (Sony) Cc: Vincenzo Frascino Cc: Yu Zhao Signed-off-by: Andrew Morton

mm/userfaultfd: allow pte_offset_map_lock() to fail

2023-06-19T23:19:15+00:00

mfill_atomic_install_pte() and mfill_atomic_pte_zeropage() treat failed pte_offset_map_lock() as -EAGAIN, which mfill_atomic() already returns to user for a similar race. Link: https://lkml.kernel.org/r/50cf3930-1bfa-4de9-a079-3da47b7ce17b@google.com Signed-off-by: Hugh Dickins Cc: Alistair Popple Cc: Anshuman Khandual Cc: Axel Rasmussen Cc: Christophe Leroy Cc: Christoph Hellwig Cc: David Hildenbrand Cc: "Huang, Ying" Cc: Ira Weiny Cc: Jason Gunthorpe Cc: Kirill A. Shutemov Cc: Lorenzo Stoakes Cc: Matthew Wilcox Cc: Mel Gorman Cc: Miaohe Lin Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Minchan Kim Cc: Naoya Horiguchi Cc: Pavel Tatashin Cc: Peter Xu Cc: Peter Zijlstra Cc: Qi Zheng Cc: Ralph Campbell Cc: Ryan Roberts Cc: SeongJae Park Cc: Song Liu Cc: Steven Price Cc: Suren Baghdasaryan Cc: Thomas Hellström Cc: Will Deacon Cc: Yang Shi Cc: Yu Zhao Cc: Zack Rusin Signed-off-by: Andrew Morton

userfaultfd: use helper function range_in_vma()

2023-04-21T21:52:02+00:00

We can use range_in_vma() to check if dst_start, dst_start + len are within the dst_vma range. Minor readability improvement. Link: https://lkml.kernel.org/r/20230417003919.930515-1-zhangpeng362@huawei.com Signed-off-by: ZhangPeng Reviewed-by: David Hildenbrand Cc: Kefeng Wang Cc: Mike Kravetz Cc: Nanyong Sun Signed-off-by: Andrew Morton