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fs/userfaultfd.c
50.7 KB
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/* * fs/userfaultfd.c * * Copyright (C) 2007 Davide Libenzi <davidel@xmailserver.org> * Copyright (C) 2008-2009 Red Hat, Inc. * Copyright (C) 2015 Red Hat, Inc. * * This work is licensed under the terms of the GNU GPL, version 2. See * the COPYING file in the top-level directory. * * Some part derived from fs/eventfd.c (anon inode setup) and * mm/ksm.c (mm hashing). */ |
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#include <linux/list.h> |
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#include <linux/hashtable.h> |
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#include <linux/sched/signal.h> |
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#include <linux/sched/mm.h> |
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#include <linux/mm.h> #include <linux/poll.h> #include <linux/slab.h> #include <linux/seq_file.h> #include <linux/file.h> #include <linux/bug.h> #include <linux/anon_inodes.h> #include <linux/syscalls.h> #include <linux/userfaultfd_k.h> #include <linux/mempolicy.h> #include <linux/ioctl.h> #include <linux/security.h> |
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#include <linux/hugetlb.h> |
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|
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static struct kmem_cache *userfaultfd_ctx_cachep __read_mostly; |
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enum userfaultfd_state { UFFD_STATE_WAIT_API, UFFD_STATE_RUNNING, }; |
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/* * Start with fault_pending_wqh and fault_wqh so they're more likely * to be in the same cacheline. */ |
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struct userfaultfd_ctx { |
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/* waitqueue head for the pending (i.e. not read) userfaults */ wait_queue_head_t fault_pending_wqh; /* waitqueue head for the userfaults */ |
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wait_queue_head_t fault_wqh; /* waitqueue head for the pseudo fd to wakeup poll/read */ wait_queue_head_t fd_wqh; |
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/* waitqueue head for events */ wait_queue_head_t event_wqh; |
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/* a refile sequence protected by fault_pending_wqh lock */ struct seqcount refile_seq; |
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/* pseudo fd refcounting */ atomic_t refcount; |
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/* userfaultfd syscall flags */ unsigned int flags; |
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/* features requested from the userspace */ unsigned int features; |
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/* state machine */ enum userfaultfd_state state; /* released */ bool released; /* mm with one ore more vmas attached to this userfaultfd_ctx */ struct mm_struct *mm; }; |
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struct userfaultfd_fork_ctx { struct userfaultfd_ctx *orig; struct userfaultfd_ctx *new; struct list_head list; }; |
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struct userfaultfd_unmap_ctx { struct userfaultfd_ctx *ctx; unsigned long start; unsigned long end; struct list_head list; }; |
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struct userfaultfd_wait_queue { |
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struct uffd_msg msg; |
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wait_queue_entry_t wq; |
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struct userfaultfd_ctx *ctx; |
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bool waken; |
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}; struct userfaultfd_wake_range { unsigned long start; unsigned long len; }; |
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static int userfaultfd_wake_function(wait_queue_entry_t *wq, unsigned mode, |
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int wake_flags, void *key) { struct userfaultfd_wake_range *range = key; int ret; struct userfaultfd_wait_queue *uwq; unsigned long start, len; uwq = container_of(wq, struct userfaultfd_wait_queue, wq); ret = 0; |
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/* len == 0 means wake all */ start = range->start; len = range->len; |
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if (len && (start > uwq->msg.arg.pagefault.address || start + len <= uwq->msg.arg.pagefault.address)) |
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goto out; |
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WRITE_ONCE(uwq->waken, true); /* |
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* The Program-Order guarantees provided by the scheduler * ensure uwq->waken is visible before the task is woken. |
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*/ |
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ret = wake_up_state(wq->private, mode); |
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if (ret) { |
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/* * Wake only once, autoremove behavior. * |
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* After the effect of list_del_init is visible to the other * CPUs, the waitqueue may disappear from under us, see the * !list_empty_careful() in handle_userfault(). * * try_to_wake_up() has an implicit smp_mb(), and the * wq->private is read before calling the extern function * "wake_up_state" (which in turns calls try_to_wake_up). |
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*/ |
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list_del_init(&wq->entry); |
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} |
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out: return ret; } /** * userfaultfd_ctx_get - Acquires a reference to the internal userfaultfd * context. * @ctx: [in] Pointer to the userfaultfd context. |
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*/ static void userfaultfd_ctx_get(struct userfaultfd_ctx *ctx) { if (!atomic_inc_not_zero(&ctx->refcount)) BUG(); } /** * userfaultfd_ctx_put - Releases a reference to the internal userfaultfd * context. * @ctx: [in] Pointer to userfaultfd context. * * The userfaultfd context reference must have been previously acquired either * with userfaultfd_ctx_get() or userfaultfd_ctx_fdget(). */ static void userfaultfd_ctx_put(struct userfaultfd_ctx *ctx) { if (atomic_dec_and_test(&ctx->refcount)) { VM_BUG_ON(spin_is_locked(&ctx->fault_pending_wqh.lock)); VM_BUG_ON(waitqueue_active(&ctx->fault_pending_wqh)); VM_BUG_ON(spin_is_locked(&ctx->fault_wqh.lock)); VM_BUG_ON(waitqueue_active(&ctx->fault_wqh)); |
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VM_BUG_ON(spin_is_locked(&ctx->event_wqh.lock)); VM_BUG_ON(waitqueue_active(&ctx->event_wqh)); |
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VM_BUG_ON(spin_is_locked(&ctx->fd_wqh.lock)); VM_BUG_ON(waitqueue_active(&ctx->fd_wqh)); |
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mmdrop(ctx->mm); |
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kmem_cache_free(userfaultfd_ctx_cachep, ctx); |
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} } |
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static inline void msg_init(struct uffd_msg *msg) |
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{ |
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BUILD_BUG_ON(sizeof(struct uffd_msg) != 32); /* * Must use memset to zero out the paddings or kernel data is * leaked to userland. */ memset(msg, 0, sizeof(struct uffd_msg)); } static inline struct uffd_msg userfault_msg(unsigned long address, unsigned int flags, |
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unsigned long reason, unsigned int features) |
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{ struct uffd_msg msg; msg_init(&msg); msg.event = UFFD_EVENT_PAGEFAULT; msg.arg.pagefault.address = address; |
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if (flags & FAULT_FLAG_WRITE) /* |
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* If UFFD_FEATURE_PAGEFAULT_FLAG_WP was set in the |
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* uffdio_api.features and UFFD_PAGEFAULT_FLAG_WRITE * was not set in a UFFD_EVENT_PAGEFAULT, it means it * was a read fault, otherwise if set it means it's * a write fault. |
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*/ |
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msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WRITE; |
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if (reason & VM_UFFD_WP) /* |
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* If UFFD_FEATURE_PAGEFAULT_FLAG_WP was set in the * uffdio_api.features and UFFD_PAGEFAULT_FLAG_WP was * not set in a UFFD_EVENT_PAGEFAULT, it means it was * a missing fault, otherwise if set it means it's a * write protect fault. |
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*/ |
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msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WP; |
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if (features & UFFD_FEATURE_THREAD_ID) |
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msg.arg.pagefault.feat.ptid = task_pid_vnr(current); |
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return msg; |
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} |
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#ifdef CONFIG_HUGETLB_PAGE /* * Same functionality as userfaultfd_must_wait below with modifications for * hugepmd ranges. */ static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, |
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struct vm_area_struct *vma, |
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unsigned long address, unsigned long flags, unsigned long reason) { struct mm_struct *mm = ctx->mm; |
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pte_t *ptep, pte; |
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bool ret = true; VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); |
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ptep = huge_pte_offset(mm, address, vma_mmu_pagesize(vma)); if (!ptep) |
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goto out; ret = false; |
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pte = huge_ptep_get(ptep); |
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/* * Lockless access: we're in a wait_event so it's ok if it * changes under us. */ |
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if (huge_pte_none(pte)) |
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ret = true; |
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if (!huge_pte_write(pte) && (reason & VM_UFFD_WP)) |
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ret = true; out: return ret; } #else static inline bool userfaultfd_huge_must_wait(struct userfaultfd_ctx *ctx, |
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struct vm_area_struct *vma, |
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unsigned long address, unsigned long flags, unsigned long reason) { return false; /* should never get here */ } #endif /* CONFIG_HUGETLB_PAGE */ |
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/* |
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* Verify the pagetables are still not ok after having reigstered into * the fault_pending_wqh to avoid userland having to UFFDIO_WAKE any * userfault that has already been resolved, if userfaultfd_read and * UFFDIO_COPY|ZEROPAGE are being run simultaneously on two different * threads. */ static inline bool userfaultfd_must_wait(struct userfaultfd_ctx *ctx, unsigned long address, unsigned long flags, unsigned long reason) { struct mm_struct *mm = ctx->mm; pgd_t *pgd; |
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p4d_t *p4d; |
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pud_t *pud; pmd_t *pmd, _pmd; pte_t *pte; bool ret = true; VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) goto out; |
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p4d = p4d_offset(pgd, address); if (!p4d_present(*p4d)) goto out; pud = pud_offset(p4d, address); |
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if (!pud_present(*pud)) goto out; pmd = pmd_offset(pud, address); /* * READ_ONCE must function as a barrier with narrower scope * and it must be equivalent to: * _pmd = *pmd; barrier(); * * This is to deal with the instability (as in * pmd_trans_unstable) of the pmd. */ _pmd = READ_ONCE(*pmd); if (!pmd_present(_pmd)) goto out; ret = false; if (pmd_trans_huge(_pmd)) goto out; /* * the pmd is stable (as in !pmd_trans_unstable) so we can re-read it * and use the standard pte_offset_map() instead of parsing _pmd. */ pte = pte_offset_map(pmd, address); /* * Lockless access: we're in a wait_event so it's ok if it * changes under us. */ if (pte_none(*pte)) ret = true; pte_unmap(pte); out: return ret; } /* |
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* The locking rules involved in returning VM_FAULT_RETRY depending on * FAULT_FLAG_ALLOW_RETRY, FAULT_FLAG_RETRY_NOWAIT and * FAULT_FLAG_KILLABLE are not straightforward. The "Caution" * recommendation in __lock_page_or_retry is not an understatement. * * If FAULT_FLAG_ALLOW_RETRY is set, the mmap_sem must be released * before returning VM_FAULT_RETRY only if FAULT_FLAG_RETRY_NOWAIT is * not set. * * If FAULT_FLAG_ALLOW_RETRY is set but FAULT_FLAG_KILLABLE is not * set, VM_FAULT_RETRY can still be returned if and only if there are * fatal_signal_pending()s, and the mmap_sem must be released before * returning it. */ |
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int handle_userfault(struct vm_fault *vmf, unsigned long reason) |
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{ |
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struct mm_struct *mm = vmf->vma->vm_mm; |
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struct userfaultfd_ctx *ctx; struct userfaultfd_wait_queue uwq; |
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int ret; |
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bool must_wait, return_to_userland; |
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long blocking_state; |
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|
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ret = VM_FAULT_SIGBUS; |
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/* * We don't do userfault handling for the final child pid update. * * We also don't do userfault handling during * coredumping. hugetlbfs has the special * follow_hugetlb_page() to skip missing pages in the * FOLL_DUMP case, anon memory also checks for FOLL_DUMP with * the no_page_table() helper in follow_page_mask(), but the * shmem_vm_ops->fault method is invoked even during * coredumping without mmap_sem and it ends up here. */ if (current->flags & (PF_EXITING|PF_DUMPCORE)) goto out; /* * Coredumping runs without mmap_sem so we can only check that * the mmap_sem is held, if PF_DUMPCORE was not set. */ WARN_ON_ONCE(!rwsem_is_locked(&mm->mmap_sem)); |
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ctx = vmf->vma->vm_userfaultfd_ctx.ctx; |
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if (!ctx) |
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goto out; |
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BUG_ON(ctx->mm != mm); VM_BUG_ON(reason & ~(VM_UFFD_MISSING|VM_UFFD_WP)); VM_BUG_ON(!(reason & VM_UFFD_MISSING) ^ !!(reason & VM_UFFD_WP)); |
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if (ctx->features & UFFD_FEATURE_SIGBUS) goto out; |
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/* * If it's already released don't get it. This avoids to loop * in __get_user_pages if userfaultfd_release waits on the * caller of handle_userfault to release the mmap_sem. */ |
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if (unlikely(ACCESS_ONCE(ctx->released))) { /* * Don't return VM_FAULT_SIGBUS in this case, so a non * cooperative manager can close the uffd after the * last UFFDIO_COPY, without risking to trigger an * involuntary SIGBUS if the process was starting the * userfaultfd while the userfaultfd was still armed * (but after the last UFFDIO_COPY). If the uffd * wasn't already closed when the userfault reached * this point, that would normally be solved by * userfaultfd_must_wait returning 'false'. * * If we were to return VM_FAULT_SIGBUS here, the non * cooperative manager would be instead forced to * always call UFFDIO_UNREGISTER before it can safely * close the uffd. */ ret = VM_FAULT_NOPAGE; |
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goto out; |
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} |
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/* * Check that we can return VM_FAULT_RETRY. * * NOTE: it should become possible to return VM_FAULT_RETRY * even if FAULT_FLAG_TRIED is set without leading to gup() * -EBUSY failures, if the userfaultfd is to be extended for * VM_UFFD_WP tracking and we intend to arm the userfault * without first stopping userland access to the memory. For * VM_UFFD_MISSING userfaults this is enough for now. */ |
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if (unlikely(!(vmf->flags & FAULT_FLAG_ALLOW_RETRY))) { |
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/* * Validate the invariant that nowait must allow retry * to be sure not to return SIGBUS erroneously on * nowait invocations. */ |
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BUG_ON(vmf->flags & FAULT_FLAG_RETRY_NOWAIT); |
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#ifdef CONFIG_DEBUG_VM if (printk_ratelimit()) { printk(KERN_WARNING |
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"FAULT_FLAG_ALLOW_RETRY missing %x ", vmf->flags); |
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dump_stack(); } #endif |
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goto out; |
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} /* * Handle nowait, not much to do other than tell it to retry * and wait. */ |
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ret = VM_FAULT_RETRY; |
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if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT) |
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goto out; |
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/* take the reference before dropping the mmap_sem */ userfaultfd_ctx_get(ctx); |
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init_waitqueue_func_entry(&uwq.wq, userfaultfd_wake_function); uwq.wq.private = current; |
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uwq.msg = userfault_msg(vmf->address, vmf->flags, reason, ctx->features); |
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uwq.ctx = ctx; |
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uwq.waken = false; |
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|
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return_to_userland = |
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(vmf->flags & (FAULT_FLAG_USER|FAULT_FLAG_KILLABLE)) == |
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(FAULT_FLAG_USER|FAULT_FLAG_KILLABLE); |
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blocking_state = return_to_userland ? TASK_INTERRUPTIBLE : TASK_KILLABLE; |
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|
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spin_lock(&ctx->fault_pending_wqh.lock); |
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/* * After the __add_wait_queue the uwq is visible to userland * through poll/read(). */ |
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__add_wait_queue(&ctx->fault_pending_wqh, &uwq.wq); /* * The smp_mb() after __set_current_state prevents the reads * following the spin_unlock to happen before the list_add in * __add_wait_queue. */ |
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set_current_state(blocking_state); |
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spin_unlock(&ctx->fault_pending_wqh.lock); |
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|
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if (!is_vm_hugetlb_page(vmf->vma)) must_wait = userfaultfd_must_wait(ctx, vmf->address, vmf->flags, reason); else |
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must_wait = userfaultfd_huge_must_wait(ctx, vmf->vma, vmf->address, |
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vmf->flags, reason); |
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up_read(&mm->mmap_sem); if (likely(must_wait && !ACCESS_ONCE(ctx->released) && |
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(return_to_userland ? !signal_pending(current) : !fatal_signal_pending(current)))) { |
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wake_up_poll(&ctx->fd_wqh, POLLIN); schedule(); |
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ret |= VM_FAULT_MAJOR; |
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/* * False wakeups can orginate even from rwsem before * up_read() however userfaults will wait either for a * targeted wakeup on the specific uwq waitqueue from * wake_userfault() or for signals or for uffd * release. */ while (!READ_ONCE(uwq.waken)) { /* * This needs the full smp_store_mb() * guarantee as the state write must be * visible to other CPUs before reading * uwq.waken from other CPUs. */ set_current_state(blocking_state); if (READ_ONCE(uwq.waken) || READ_ONCE(ctx->released) || (return_to_userland ? signal_pending(current) : fatal_signal_pending(current))) break; schedule(); } |
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} |
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|
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__set_current_state(TASK_RUNNING); |
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|
dfa37dc3f userfaultfd: allo... |
501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 |
if (return_to_userland) { if (signal_pending(current) && !fatal_signal_pending(current)) { /* * If we got a SIGSTOP or SIGCONT and this is * a normal userland page fault, just let * userland return so the signal will be * handled and gdb debugging works. The page * fault code immediately after we return from * this function is going to release the * mmap_sem and it's not depending on it * (unlike gup would if we were not to return * VM_FAULT_RETRY). * * If a fatal signal is pending we still take * the streamlined VM_FAULT_RETRY failure path * and there's no need to retake the mmap_sem * in such case. */ down_read(&mm->mmap_sem); |
6bbc4a414 userfaultfd: shme... |
521 |
ret = VM_FAULT_NOPAGE; |
dfa37dc3f userfaultfd: allo... |
522 523 |
} } |
15b726ef0 userfaultfd: opti... |
524 525 526 527 528 529 530 531 532 533 534 535 536 |
/* * Here we race with the list_del; list_add in * userfaultfd_ctx_read(), however because we don't ever run * list_del_init() to refile across the two lists, the prev * and next pointers will never point to self. list_add also * would never let any of the two pointers to point to * self. So list_empty_careful won't risk to see both pointers * pointing to self at any time during the list refile. The * only case where list_del_init() is called is the full * removal in the wake function and there we don't re-list_add * and it's fine not to block on the spinlock. The uwq on this * kernel stack can be released after the list_del_init. */ |
2055da973 sched/wait: Disam... |
537 |
if (!list_empty_careful(&uwq.wq.entry)) { |
15b726ef0 userfaultfd: opti... |
538 539 540 541 542 |
spin_lock(&ctx->fault_pending_wqh.lock); /* * No need of list_del_init(), the uwq on the stack * will be freed shortly anyway. */ |
2055da973 sched/wait: Disam... |
543 |
list_del(&uwq.wq.entry); |
15b726ef0 userfaultfd: opti... |
544 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
545 |
} |
86039bd3b userfaultfd: add ... |
546 547 548 549 550 551 |
/* * ctx may go away after this if the userfault pseudo fd is * already released. */ userfaultfd_ctx_put(ctx); |
ba85c702e userfaultfd: wake... |
552 553 |
out: return ret; |
86039bd3b userfaultfd: add ... |
554 |
} |
8c9e7bb7a userfaultfd: non-... |
555 556 |
static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx, struct userfaultfd_wait_queue *ewq) |
9cd75c3cd userfaultfd: non-... |
557 |
{ |
319122a71 userfaultfd: clea... |
558 |
struct userfaultfd_ctx *release_new_ctx; |
9a69a829f userfaultfd: non-... |
559 560 |
if (WARN_ON_ONCE(current->flags & PF_EXITING)) goto out; |
9cd75c3cd userfaultfd: non-... |
561 562 563 |
ewq->ctx = ctx; init_waitqueue_entry(&ewq->wq, current); |
319122a71 userfaultfd: clea... |
564 |
release_new_ctx = NULL; |
9cd75c3cd userfaultfd: non-... |
565 566 567 568 569 570 571 572 573 574 575 576 577 |
spin_lock(&ctx->event_wqh.lock); /* * After the __add_wait_queue the uwq is visible to userland * through poll/read(). */ __add_wait_queue(&ctx->event_wqh, &ewq->wq); for (;;) { set_current_state(TASK_KILLABLE); if (ewq->msg.event == 0) break; if (ACCESS_ONCE(ctx->released) || fatal_signal_pending(current)) { |
384632e67 userfaultfd: non-... |
578 579 580 581 582 583 |
/* * &ewq->wq may be queued in fork_event, but * __remove_wait_queue ignores the head * parameter. It would be a problem if it * didn't. */ |
9cd75c3cd userfaultfd: non-... |
584 |
__remove_wait_queue(&ctx->event_wqh, &ewq->wq); |
7eb76d457 userfaultfd: non-... |
585 586 587 588 589 590 |
if (ewq->msg.event == UFFD_EVENT_FORK) { struct userfaultfd_ctx *new; new = (struct userfaultfd_ctx *) (unsigned long) ewq->msg.arg.reserved.reserved1; |
319122a71 userfaultfd: clea... |
591 |
release_new_ctx = new; |
7eb76d457 userfaultfd: non-... |
592 |
} |
9cd75c3cd userfaultfd: non-... |
593 594 595 596 597 598 599 600 601 602 603 604 |
break; } spin_unlock(&ctx->event_wqh.lock); wake_up_poll(&ctx->fd_wqh, POLLIN); schedule(); spin_lock(&ctx->event_wqh.lock); } __set_current_state(TASK_RUNNING); spin_unlock(&ctx->event_wqh.lock); |
319122a71 userfaultfd: clea... |
605 606 607 608 609 610 611 |
if (release_new_ctx) { struct vm_area_struct *vma; struct mm_struct *mm = release_new_ctx->mm; /* the various vma->vm_userfaultfd_ctx still points to it */ down_write(&mm->mmap_sem); for (vma = mm->mmap; vma; vma = vma->vm_next) |
0eba9f5d3 userfaultfd: remo... |
612 |
if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx) { |
319122a71 userfaultfd: clea... |
613 |
vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; |
0eba9f5d3 userfaultfd: remo... |
614 615 |
vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING); } |
319122a71 userfaultfd: clea... |
616 617 618 619 |
up_write(&mm->mmap_sem); userfaultfd_ctx_put(release_new_ctx); } |
9cd75c3cd userfaultfd: non-... |
620 621 622 623 |
/* * ctx may go away after this if the userfault pseudo fd is * already released. */ |
9a69a829f userfaultfd: non-... |
624 |
out: |
9cd75c3cd userfaultfd: non-... |
625 |
userfaultfd_ctx_put(ctx); |
9cd75c3cd userfaultfd: non-... |
626 627 628 629 630 631 632 633 634 |
} static void userfaultfd_event_complete(struct userfaultfd_ctx *ctx, struct userfaultfd_wait_queue *ewq) { ewq->msg.event = 0; wake_up_locked(&ctx->event_wqh); __remove_wait_queue(&ctx->event_wqh, &ewq->wq); } |
893e26e61 userfaultfd: non-... |
635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 |
int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs) { struct userfaultfd_ctx *ctx = NULL, *octx; struct userfaultfd_fork_ctx *fctx; octx = vma->vm_userfaultfd_ctx.ctx; if (!octx || !(octx->features & UFFD_FEATURE_EVENT_FORK)) { vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING); return 0; } list_for_each_entry(fctx, fcs, list) if (fctx->orig == octx) { ctx = fctx->new; break; } if (!ctx) { fctx = kmalloc(sizeof(*fctx), GFP_KERNEL); if (!fctx) return -ENOMEM; ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL); if (!ctx) { kfree(fctx); return -ENOMEM; } atomic_set(&ctx->refcount, 1); ctx->flags = octx->flags; ctx->state = UFFD_STATE_RUNNING; ctx->features = octx->features; ctx->released = false; ctx->mm = vma->vm_mm; |
d3aadc8ed userfaultfd: non-... |
670 |
atomic_inc(&ctx->mm->mm_count); |
893e26e61 userfaultfd: non-... |
671 672 673 674 675 676 677 678 679 680 |
userfaultfd_ctx_get(octx); fctx->orig = octx; fctx->new = ctx; list_add_tail(&fctx->list, fcs); } vma->vm_userfaultfd_ctx.ctx = ctx; return 0; } |
8c9e7bb7a userfaultfd: non-... |
681 |
static void dup_fctx(struct userfaultfd_fork_ctx *fctx) |
893e26e61 userfaultfd: non-... |
682 683 684 685 686 687 688 689 |
{ struct userfaultfd_ctx *ctx = fctx->orig; struct userfaultfd_wait_queue ewq; msg_init(&ewq.msg); ewq.msg.event = UFFD_EVENT_FORK; ewq.msg.arg.reserved.reserved1 = (unsigned long)fctx->new; |
8c9e7bb7a userfaultfd: non-... |
690 |
userfaultfd_event_wait_completion(ctx, &ewq); |
893e26e61 userfaultfd: non-... |
691 692 693 694 |
} void dup_userfaultfd_complete(struct list_head *fcs) { |
893e26e61 userfaultfd: non-... |
695 696 697 |
struct userfaultfd_fork_ctx *fctx, *n; list_for_each_entry_safe(fctx, n, fcs, list) { |
8c9e7bb7a userfaultfd: non-... |
698 |
dup_fctx(fctx); |
893e26e61 userfaultfd: non-... |
699 700 701 702 |
list_del(&fctx->list); kfree(fctx); } } |
72f87654c userfaultfd: non-... |
703 704 705 706 707 708 709 710 711 712 713 |
void mremap_userfaultfd_prep(struct vm_area_struct *vma, struct vm_userfaultfd_ctx *vm_ctx) { struct userfaultfd_ctx *ctx; ctx = vma->vm_userfaultfd_ctx.ctx; if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) { vm_ctx->ctx = ctx; userfaultfd_ctx_get(ctx); } } |
90794bf19 userfaultfd: non-... |
714 |
void mremap_userfaultfd_complete(struct vm_userfaultfd_ctx *vm_ctx, |
72f87654c userfaultfd: non-... |
715 716 717 |
unsigned long from, unsigned long to, unsigned long len) { |
90794bf19 userfaultfd: non-... |
718 |
struct userfaultfd_ctx *ctx = vm_ctx->ctx; |
72f87654c userfaultfd: non-... |
719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 |
struct userfaultfd_wait_queue ewq; if (!ctx) return; if (to & ~PAGE_MASK) { userfaultfd_ctx_put(ctx); return; } msg_init(&ewq.msg); ewq.msg.event = UFFD_EVENT_REMAP; ewq.msg.arg.remap.from = from; ewq.msg.arg.remap.to = to; ewq.msg.arg.remap.len = len; userfaultfd_event_wait_completion(ctx, &ewq); } |
70ccb92fd userfaultfd: non-... |
738 |
bool userfaultfd_remove(struct vm_area_struct *vma, |
d811914d8 userfaultfd: non-... |
739 |
unsigned long start, unsigned long end) |
05ce77249 userfaultfd: non-... |
740 741 742 743 744 745 |
{ struct mm_struct *mm = vma->vm_mm; struct userfaultfd_ctx *ctx; struct userfaultfd_wait_queue ewq; ctx = vma->vm_userfaultfd_ctx.ctx; |
d811914d8 userfaultfd: non-... |
746 |
if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_REMOVE)) |
70ccb92fd userfaultfd: non-... |
747 |
return true; |
05ce77249 userfaultfd: non-... |
748 749 750 |
userfaultfd_ctx_get(ctx); up_read(&mm->mmap_sem); |
05ce77249 userfaultfd: non-... |
751 |
msg_init(&ewq.msg); |
d811914d8 userfaultfd: non-... |
752 753 754 |
ewq.msg.event = UFFD_EVENT_REMOVE; ewq.msg.arg.remove.start = start; ewq.msg.arg.remove.end = end; |
05ce77249 userfaultfd: non-... |
755 756 |
userfaultfd_event_wait_completion(ctx, &ewq); |
70ccb92fd userfaultfd: non-... |
757 |
return false; |
05ce77249 userfaultfd: non-... |
758 |
} |
897ab3e0c userfaultfd: non-... |
759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 |
static bool has_unmap_ctx(struct userfaultfd_ctx *ctx, struct list_head *unmaps, unsigned long start, unsigned long end) { struct userfaultfd_unmap_ctx *unmap_ctx; list_for_each_entry(unmap_ctx, unmaps, list) if (unmap_ctx->ctx == ctx && unmap_ctx->start == start && unmap_ctx->end == end) return true; return false; } int userfaultfd_unmap_prep(struct vm_area_struct *vma, unsigned long start, unsigned long end, struct list_head *unmaps) { for ( ; vma && vma->vm_start < end; vma = vma->vm_next) { struct userfaultfd_unmap_ctx *unmap_ctx; struct userfaultfd_ctx *ctx = vma->vm_userfaultfd_ctx.ctx; if (!ctx || !(ctx->features & UFFD_FEATURE_EVENT_UNMAP) || has_unmap_ctx(ctx, unmaps, start, end)) continue; unmap_ctx = kzalloc(sizeof(*unmap_ctx), GFP_KERNEL); if (!unmap_ctx) return -ENOMEM; userfaultfd_ctx_get(ctx); unmap_ctx->ctx = ctx; unmap_ctx->start = start; unmap_ctx->end = end; list_add_tail(&unmap_ctx->list, unmaps); } return 0; } void userfaultfd_unmap_complete(struct mm_struct *mm, struct list_head *uf) { struct userfaultfd_unmap_ctx *ctx, *n; struct userfaultfd_wait_queue ewq; list_for_each_entry_safe(ctx, n, uf, list) { msg_init(&ewq.msg); ewq.msg.event = UFFD_EVENT_UNMAP; ewq.msg.arg.remove.start = ctx->start; ewq.msg.arg.remove.end = ctx->end; userfaultfd_event_wait_completion(ctx->ctx, &ewq); list_del(&ctx->list); kfree(ctx); } } |
86039bd3b userfaultfd: add ... |
816 817 818 819 820 821 822 823 824 825 |
static int userfaultfd_release(struct inode *inode, struct file *file) { struct userfaultfd_ctx *ctx = file->private_data; struct mm_struct *mm = ctx->mm; struct vm_area_struct *vma, *prev; /* len == 0 means wake all */ struct userfaultfd_wake_range range = { .len = 0, }; unsigned long new_flags; ACCESS_ONCE(ctx->released) = true; |
d2005e3f4 userfaultfd: don'... |
826 827 |
if (!mmget_not_zero(mm)) goto wakeup; |
86039bd3b userfaultfd: add ... |
828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 |
/* * Flush page faults out of all CPUs. NOTE: all page faults * must be retried without returning VM_FAULT_SIGBUS if * userfaultfd_ctx_get() succeeds but vma->vma_userfault_ctx * changes while handle_userfault released the mmap_sem. So * it's critical that released is set to true (above), before * taking the mmap_sem for writing. */ down_write(&mm->mmap_sem); prev = NULL; for (vma = mm->mmap; vma; vma = vma->vm_next) { cond_resched(); BUG_ON(!!vma->vm_userfaultfd_ctx.ctx ^ !!(vma->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP))); if (vma->vm_userfaultfd_ctx.ctx != ctx) { prev = vma; continue; } new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP); prev = vma_merge(mm, prev, vma->vm_start, vma->vm_end, new_flags, vma->anon_vma, vma->vm_file, vma->vm_pgoff, vma_policy(vma), NULL_VM_UFFD_CTX); if (prev) vma = prev; else prev = vma; vma->vm_flags = new_flags; vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; } up_write(&mm->mmap_sem); |
d2005e3f4 userfaultfd: don'... |
860 861 |
mmput(mm); wakeup: |
86039bd3b userfaultfd: add ... |
862 |
/* |
15b726ef0 userfaultfd: opti... |
863 |
* After no new page faults can wait on this fault_*wqh, flush |
86039bd3b userfaultfd: add ... |
864 |
* the last page faults that may have been already waiting on |
15b726ef0 userfaultfd: opti... |
865 |
* the fault_*wqh. |
86039bd3b userfaultfd: add ... |
866 |
*/ |
15b726ef0 userfaultfd: opti... |
867 |
spin_lock(&ctx->fault_pending_wqh.lock); |
ac5be6b47 userfaultfd: reve... |
868 869 |
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, &range); __wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, &range); |
15b726ef0 userfaultfd: opti... |
870 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
871 |
|
5a18b64e3 userfaultfd: non-... |
872 873 |
/* Flush pending events that may still wait on event_wqh */ wake_up_all(&ctx->event_wqh); |
86039bd3b userfaultfd: add ... |
874 875 876 877 |
wake_up_poll(&ctx->fd_wqh, POLLHUP); userfaultfd_ctx_put(ctx); return 0; } |
15b726ef0 userfaultfd: opti... |
878 |
/* fault_pending_wqh.lock must be hold by the caller */ |
6dcc27fd3 userfaultfd: non-... |
879 880 |
static inline struct userfaultfd_wait_queue *find_userfault_in( wait_queue_head_t *wqh) |
86039bd3b userfaultfd: add ... |
881 |
{ |
ac6424b98 sched/wait: Renam... |
882 |
wait_queue_entry_t *wq; |
15b726ef0 userfaultfd: opti... |
883 |
struct userfaultfd_wait_queue *uwq; |
86039bd3b userfaultfd: add ... |
884 |
|
6dcc27fd3 userfaultfd: non-... |
885 |
VM_BUG_ON(!spin_is_locked(&wqh->lock)); |
86039bd3b userfaultfd: add ... |
886 |
|
15b726ef0 userfaultfd: opti... |
887 |
uwq = NULL; |
6dcc27fd3 userfaultfd: non-... |
888 |
if (!waitqueue_active(wqh)) |
15b726ef0 userfaultfd: opti... |
889 890 |
goto out; /* walk in reverse to provide FIFO behavior to read userfaults */ |
2055da973 sched/wait: Disam... |
891 |
wq = list_last_entry(&wqh->head, typeof(*wq), entry); |
15b726ef0 userfaultfd: opti... |
892 893 894 |
uwq = container_of(wq, struct userfaultfd_wait_queue, wq); out: return uwq; |
86039bd3b userfaultfd: add ... |
895 |
} |
6dcc27fd3 userfaultfd: non-... |
896 897 898 899 900 901 |
static inline struct userfaultfd_wait_queue *find_userfault( struct userfaultfd_ctx *ctx) { return find_userfault_in(&ctx->fault_pending_wqh); } |
86039bd3b userfaultfd: add ... |
902 |
|
9cd75c3cd userfaultfd: non-... |
903 904 905 906 907 |
static inline struct userfaultfd_wait_queue *find_userfault_evt( struct userfaultfd_ctx *ctx) { return find_userfault_in(&ctx->event_wqh); } |
86039bd3b userfaultfd: add ... |
908 909 910 911 912 913 914 915 916 917 918 |
static unsigned int userfaultfd_poll(struct file *file, poll_table *wait) { struct userfaultfd_ctx *ctx = file->private_data; unsigned int ret; poll_wait(file, &ctx->fd_wqh, wait); switch (ctx->state) { case UFFD_STATE_WAIT_API: return POLLERR; case UFFD_STATE_RUNNING: |
ba85c702e userfaultfd: wake... |
919 920 921 922 923 924 |
/* * poll() never guarantees that read won't block. * userfaults can be waken before they're read(). */ if (unlikely(!(file->f_flags & O_NONBLOCK))) return POLLERR; |
15b726ef0 userfaultfd: opti... |
925 926 927 928 929 930 931 932 933 934 935 936 937 938 |
/* * lockless access to see if there are pending faults * __pollwait last action is the add_wait_queue but * the spin_unlock would allow the waitqueue_active to * pass above the actual list_add inside * add_wait_queue critical section. So use a full * memory barrier to serialize the list_add write of * add_wait_queue() with the waitqueue_active read * below. */ ret = 0; smp_mb(); if (waitqueue_active(&ctx->fault_pending_wqh)) ret = POLLIN; |
9cd75c3cd userfaultfd: non-... |
939 940 |
else if (waitqueue_active(&ctx->event_wqh)) ret = POLLIN; |
86039bd3b userfaultfd: add ... |
941 942 |
return ret; default: |
8474901a3 userfaultfd: conv... |
943 944 |
WARN_ON_ONCE(1); return POLLERR; |
86039bd3b userfaultfd: add ... |
945 946 |
} } |
893e26e61 userfaultfd: non-... |
947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 |
static const struct file_operations userfaultfd_fops; static int resolve_userfault_fork(struct userfaultfd_ctx *ctx, struct userfaultfd_ctx *new, struct uffd_msg *msg) { int fd; struct file *file; unsigned int flags = new->flags & UFFD_SHARED_FCNTL_FLAGS; fd = get_unused_fd_flags(flags); if (fd < 0) return fd; file = anon_inode_getfile("[userfaultfd]", &userfaultfd_fops, new, O_RDWR | flags); if (IS_ERR(file)) { put_unused_fd(fd); return PTR_ERR(file); } fd_install(fd, file); msg->arg.reserved.reserved1 = 0; msg->arg.fork.ufd = fd; return 0; } |
86039bd3b userfaultfd: add ... |
974 |
static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait, |
a9b85f941 userfaultfd: chan... |
975 |
struct uffd_msg *msg) |
86039bd3b userfaultfd: add ... |
976 977 978 |
{ ssize_t ret; DECLARE_WAITQUEUE(wait, current); |
15b726ef0 userfaultfd: opti... |
979 |
struct userfaultfd_wait_queue *uwq; |
893e26e61 userfaultfd: non-... |
980 981 982 983 984 985 986 987 988 |
/* * Handling fork event requires sleeping operations, so * we drop the event_wqh lock, then do these ops, then * lock it back and wake up the waiter. While the lock is * dropped the ewq may go away so we keep track of it * carefully. */ LIST_HEAD(fork_event); struct userfaultfd_ctx *fork_nctx = NULL; |
86039bd3b userfaultfd: add ... |
989 |
|
15b726ef0 userfaultfd: opti... |
990 |
/* always take the fd_wqh lock before the fault_pending_wqh lock */ |
86039bd3b userfaultfd: add ... |
991 992 993 994 |
spin_lock(&ctx->fd_wqh.lock); __add_wait_queue(&ctx->fd_wqh, &wait); for (;;) { set_current_state(TASK_INTERRUPTIBLE); |
15b726ef0 userfaultfd: opti... |
995 996 997 |
spin_lock(&ctx->fault_pending_wqh.lock); uwq = find_userfault(ctx); if (uwq) { |
86039bd3b userfaultfd: add ... |
998 |
/* |
2c5b7e1be userfaultfd: avoi... |
999 1000 1001 1002 1003 1004 1005 1006 1007 |
* Use a seqcount to repeat the lockless check * in wake_userfault() to avoid missing * wakeups because during the refile both * waitqueue could become empty if this is the * only userfault. */ write_seqcount_begin(&ctx->refile_seq); /* |
15b726ef0 userfaultfd: opti... |
1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 |
* The fault_pending_wqh.lock prevents the uwq * to disappear from under us. * * Refile this userfault from * fault_pending_wqh to fault_wqh, it's not * pending anymore after we read it. * * Use list_del() by hand (as * userfaultfd_wake_function also uses * list_del_init() by hand) to be sure nobody * changes __remove_wait_queue() to use * list_del_init() in turn breaking the * !list_empty_careful() check in |
2055da973 sched/wait: Disam... |
1021 |
* handle_userfault(). The uwq->wq.head list |
15b726ef0 userfaultfd: opti... |
1022 1023 1024 1025 1026 |
* must never be empty at any time during the * refile, or the waitqueue could disappear * from under us. The "wait_queue_head_t" * parameter of __remove_wait_queue() is unused * anyway. |
86039bd3b userfaultfd: add ... |
1027 |
*/ |
2055da973 sched/wait: Disam... |
1028 |
list_del(&uwq->wq.entry); |
15b726ef0 userfaultfd: opti... |
1029 |
__add_wait_queue(&ctx->fault_wqh, &uwq->wq); |
2c5b7e1be userfaultfd: avoi... |
1030 |
write_seqcount_end(&ctx->refile_seq); |
a9b85f941 userfaultfd: chan... |
1031 1032 |
/* careful to always initialize msg if ret == 0 */ *msg = uwq->msg; |
15b726ef0 userfaultfd: opti... |
1033 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
1034 1035 1036 |
ret = 0; break; } |
15b726ef0 userfaultfd: opti... |
1037 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
9cd75c3cd userfaultfd: non-... |
1038 1039 1040 1041 1042 |
spin_lock(&ctx->event_wqh.lock); uwq = find_userfault_evt(ctx); if (uwq) { *msg = uwq->msg; |
893e26e61 userfaultfd: non-... |
1043 1044 1045 1046 |
if (uwq->msg.event == UFFD_EVENT_FORK) { fork_nctx = (struct userfaultfd_ctx *) (unsigned long) uwq->msg.arg.reserved.reserved1; |
2055da973 sched/wait: Disam... |
1047 |
list_move(&uwq->wq.entry, &fork_event); |
384632e67 userfaultfd: non-... |
1048 1049 1050 1051 1052 1053 |
/* * fork_nctx can be freed as soon as * we drop the lock, unless we take a * reference on it. */ userfaultfd_ctx_get(fork_nctx); |
893e26e61 userfaultfd: non-... |
1054 1055 1056 1057 |
spin_unlock(&ctx->event_wqh.lock); ret = 0; break; } |
9cd75c3cd userfaultfd: non-... |
1058 1059 1060 1061 1062 1063 |
userfaultfd_event_complete(ctx, uwq); spin_unlock(&ctx->event_wqh.lock); ret = 0; break; } spin_unlock(&ctx->event_wqh.lock); |
86039bd3b userfaultfd: add ... |
1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 |
if (signal_pending(current)) { ret = -ERESTARTSYS; break; } if (no_wait) { ret = -EAGAIN; break; } spin_unlock(&ctx->fd_wqh.lock); schedule(); spin_lock(&ctx->fd_wqh.lock); } __remove_wait_queue(&ctx->fd_wqh, &wait); __set_current_state(TASK_RUNNING); spin_unlock(&ctx->fd_wqh.lock); |
893e26e61 userfaultfd: non-... |
1079 1080 |
if (!ret && msg->event == UFFD_EVENT_FORK) { ret = resolve_userfault_fork(ctx, fork_nctx, msg); |
384632e67 userfaultfd: non-... |
1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 |
spin_lock(&ctx->event_wqh.lock); if (!list_empty(&fork_event)) { /* * The fork thread didn't abort, so we can * drop the temporary refcount. */ userfaultfd_ctx_put(fork_nctx); uwq = list_first_entry(&fork_event, typeof(*uwq), wq.entry); /* * If fork_event list wasn't empty and in turn * the event wasn't already released by fork * (the event is allocated on fork kernel * stack), put the event back to its place in * the event_wq. fork_event head will be freed * as soon as we return so the event cannot * stay queued there no matter the current * "ret" value. */ list_del(&uwq->wq.entry); __add_wait_queue(&ctx->event_wqh, &uwq->wq); |
893e26e61 userfaultfd: non-... |
1104 |
|
384632e67 userfaultfd: non-... |
1105 1106 1107 1108 1109 1110 |
/* * Leave the event in the waitqueue and report * error to userland if we failed to resolve * the userfault fork. */ if (likely(!ret)) |
893e26e61 userfaultfd: non-... |
1111 |
userfaultfd_event_complete(ctx, uwq); |
384632e67 userfaultfd: non-... |
1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 |
} else { /* * Here the fork thread aborted and the * refcount from the fork thread on fork_nctx * has already been released. We still hold * the reference we took before releasing the * lock above. If resolve_userfault_fork * failed we've to drop it because the * fork_nctx has to be freed in such case. If * it succeeded we'll hold it because the new * uffd references it. */ if (ret) userfaultfd_ctx_put(fork_nctx); |
893e26e61 userfaultfd: non-... |
1126 |
} |
384632e67 userfaultfd: non-... |
1127 |
spin_unlock(&ctx->event_wqh.lock); |
893e26e61 userfaultfd: non-... |
1128 |
} |
86039bd3b userfaultfd: add ... |
1129 1130 1131 1132 1133 1134 1135 1136 |
return ret; } static ssize_t userfaultfd_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) { struct userfaultfd_ctx *ctx = file->private_data; ssize_t _ret, ret = 0; |
a9b85f941 userfaultfd: chan... |
1137 |
struct uffd_msg msg; |
86039bd3b userfaultfd: add ... |
1138 1139 1140 1141 |
int no_wait = file->f_flags & O_NONBLOCK; if (ctx->state == UFFD_STATE_WAIT_API) return -EINVAL; |
86039bd3b userfaultfd: add ... |
1142 1143 |
for (;;) { |
a9b85f941 userfaultfd: chan... |
1144 |
if (count < sizeof(msg)) |
86039bd3b userfaultfd: add ... |
1145 |
return ret ? ret : -EINVAL; |
a9b85f941 userfaultfd: chan... |
1146 |
_ret = userfaultfd_ctx_read(ctx, no_wait, &msg); |
86039bd3b userfaultfd: add ... |
1147 1148 |
if (_ret < 0) return ret ? ret : _ret; |
a9b85f941 userfaultfd: chan... |
1149 |
if (copy_to_user((__u64 __user *) buf, &msg, sizeof(msg))) |
86039bd3b userfaultfd: add ... |
1150 |
return ret ? ret : -EFAULT; |
a9b85f941 userfaultfd: chan... |
1151 1152 1153 |
ret += sizeof(msg); buf += sizeof(msg); count -= sizeof(msg); |
86039bd3b userfaultfd: add ... |
1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 |
/* * Allow to read more than one fault at time but only * block if waiting for the very first one. */ no_wait = O_NONBLOCK; } } static void __wake_userfault(struct userfaultfd_ctx *ctx, struct userfaultfd_wake_range *range) { |
15b726ef0 userfaultfd: opti... |
1165 |
spin_lock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
1166 |
/* wake all in the range and autoremove */ |
15b726ef0 userfaultfd: opti... |
1167 |
if (waitqueue_active(&ctx->fault_pending_wqh)) |
ac5be6b47 userfaultfd: reve... |
1168 |
__wake_up_locked_key(&ctx->fault_pending_wqh, TASK_NORMAL, |
15b726ef0 userfaultfd: opti... |
1169 1170 |
range); if (waitqueue_active(&ctx->fault_wqh)) |
ac5be6b47 userfaultfd: reve... |
1171 |
__wake_up_locked_key(&ctx->fault_wqh, TASK_NORMAL, range); |
15b726ef0 userfaultfd: opti... |
1172 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
1173 1174 1175 1176 1177 |
} static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx, struct userfaultfd_wake_range *range) { |
2c5b7e1be userfaultfd: avoi... |
1178 1179 |
unsigned seq; bool need_wakeup; |
86039bd3b userfaultfd: add ... |
1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 |
/* * To be sure waitqueue_active() is not reordered by the CPU * before the pagetable update, use an explicit SMP memory * barrier here. PT lock release or up_read(mmap_sem) still * have release semantics that can allow the * waitqueue_active() to be reordered before the pte update. */ smp_mb(); /* * Use waitqueue_active because it's very frequent to * change the address space atomically even if there are no * userfaults yet. So we take the spinlock only when we're * sure we've userfaults to wake. */ |
2c5b7e1be userfaultfd: avoi... |
1195 1196 1197 1198 1199 1200 1201 |
do { seq = read_seqcount_begin(&ctx->refile_seq); need_wakeup = waitqueue_active(&ctx->fault_pending_wqh) || waitqueue_active(&ctx->fault_wqh); cond_resched(); } while (read_seqcount_retry(&ctx->refile_seq, seq)); if (need_wakeup) |
86039bd3b userfaultfd: add ... |
1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 |
__wake_userfault(ctx, range); } static __always_inline int validate_range(struct mm_struct *mm, __u64 start, __u64 len) { __u64 task_size = mm->task_size; if (start & ~PAGE_MASK) return -EINVAL; if (len & ~PAGE_MASK) return -EINVAL; if (!len) return -EINVAL; if (start < mmap_min_addr) return -EINVAL; if (start >= task_size) return -EINVAL; if (len > task_size - start) return -EINVAL; return 0; } |
ba6907db6 userfaultfd: intr... |
1224 1225 |
static inline bool vma_can_userfault(struct vm_area_struct *vma) { |
cac673292 userfaultfd: shme... |
1226 1227 |
return vma_is_anonymous(vma) || is_vm_hugetlb_page(vma) || vma_is_shmem(vma); |
ba6907db6 userfaultfd: intr... |
1228 |
} |
86039bd3b userfaultfd: add ... |
1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 |
static int userfaultfd_register(struct userfaultfd_ctx *ctx, unsigned long arg) { struct mm_struct *mm = ctx->mm; struct vm_area_struct *vma, *prev, *cur; int ret; struct uffdio_register uffdio_register; struct uffdio_register __user *user_uffdio_register; unsigned long vm_flags, new_flags; bool found; |
ce53e8e6f userfaultfd: repo... |
1239 |
bool basic_ioctls; |
86039bd3b userfaultfd: add ... |
1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 |
unsigned long start, end, vma_end; user_uffdio_register = (struct uffdio_register __user *) arg; ret = -EFAULT; if (copy_from_user(&uffdio_register, user_uffdio_register, sizeof(uffdio_register)-sizeof(__u64))) goto out; ret = -EINVAL; if (!uffdio_register.mode) goto out; if (uffdio_register.mode & ~(UFFDIO_REGISTER_MODE_MISSING| UFFDIO_REGISTER_MODE_WP)) goto out; vm_flags = 0; if (uffdio_register.mode & UFFDIO_REGISTER_MODE_MISSING) vm_flags |= VM_UFFD_MISSING; if (uffdio_register.mode & UFFDIO_REGISTER_MODE_WP) { vm_flags |= VM_UFFD_WP; /* * FIXME: remove the below error constraint by * implementing the wprotect tracking mode. */ ret = -EINVAL; goto out; } ret = validate_range(mm, uffdio_register.range.start, uffdio_register.range.len); if (ret) goto out; start = uffdio_register.range.start; end = start + uffdio_register.range.len; |
d2005e3f4 userfaultfd: don'... |
1275 1276 1277 |
ret = -ENOMEM; if (!mmget_not_zero(mm)) goto out; |
86039bd3b userfaultfd: add ... |
1278 1279 |
down_write(&mm->mmap_sem); vma = find_vma_prev(mm, start, &prev); |
86039bd3b userfaultfd: add ... |
1280 1281 1282 1283 1284 1285 1286 1287 1288 |
if (!vma) goto out_unlock; /* check that there's at least one vma in the range */ ret = -EINVAL; if (vma->vm_start >= end) goto out_unlock; /* |
cab350afc userfaultfd: huge... |
1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 |
* If the first vma contains huge pages, make sure start address * is aligned to huge page size. */ if (is_vm_hugetlb_page(vma)) { unsigned long vma_hpagesize = vma_kernel_pagesize(vma); if (start & (vma_hpagesize - 1)) goto out_unlock; } /* |
86039bd3b userfaultfd: add ... |
1300 |
* Search for not compatible vmas. |
86039bd3b userfaultfd: add ... |
1301 1302 |
*/ found = false; |
ce53e8e6f userfaultfd: repo... |
1303 |
basic_ioctls = false; |
86039bd3b userfaultfd: add ... |
1304 1305 1306 1307 1308 1309 1310 1311 |
for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) { cond_resched(); BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^ !!(cur->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP))); /* check not compatible vmas */ ret = -EINVAL; |
ba6907db6 userfaultfd: intr... |
1312 |
if (!vma_can_userfault(cur)) |
86039bd3b userfaultfd: add ... |
1313 |
goto out_unlock; |
cab350afc userfaultfd: huge... |
1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 |
/* * If this vma contains ending address, and huge pages * check alignment. */ if (is_vm_hugetlb_page(cur) && end <= cur->vm_end && end > cur->vm_start) { unsigned long vma_hpagesize = vma_kernel_pagesize(cur); ret = -EINVAL; if (end & (vma_hpagesize - 1)) goto out_unlock; } |
86039bd3b userfaultfd: add ... |
1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 |
/* * Check that this vma isn't already owned by a * different userfaultfd. We can't allow more than one * userfaultfd to own a single vma simultaneously or we * wouldn't know which one to deliver the userfaults to. */ ret = -EBUSY; if (cur->vm_userfaultfd_ctx.ctx && cur->vm_userfaultfd_ctx.ctx != ctx) goto out_unlock; |
cab350afc userfaultfd: huge... |
1338 1339 1340 |
/* * Note vmas containing huge pages */ |
ce53e8e6f userfaultfd: repo... |
1341 1342 |
if (is_vm_hugetlb_page(cur)) basic_ioctls = true; |
cab350afc userfaultfd: huge... |
1343 |
|
86039bd3b userfaultfd: add ... |
1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 |
found = true; } BUG_ON(!found); if (vma->vm_start < start) prev = vma; ret = 0; do { cond_resched(); |
ba6907db6 userfaultfd: intr... |
1354 |
BUG_ON(!vma_can_userfault(vma)); |
86039bd3b userfaultfd: add ... |
1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 |
BUG_ON(vma->vm_userfaultfd_ctx.ctx && vma->vm_userfaultfd_ctx.ctx != ctx); /* * Nothing to do: this vma is already registered into this * userfaultfd and with the right tracking mode too. */ if (vma->vm_userfaultfd_ctx.ctx == ctx && (vma->vm_flags & vm_flags) == vm_flags) goto skip; if (vma->vm_start > start) start = vma->vm_start; vma_end = min(end, vma->vm_end); new_flags = (vma->vm_flags & ~vm_flags) | vm_flags; prev = vma_merge(mm, prev, start, vma_end, new_flags, vma->anon_vma, vma->vm_file, vma->vm_pgoff, vma_policy(vma), ((struct vm_userfaultfd_ctx){ ctx })); if (prev) { vma = prev; goto next; } if (vma->vm_start < start) { ret = split_vma(mm, vma, start, 1); if (ret) break; } if (vma->vm_end > end) { ret = split_vma(mm, vma, end, 0); if (ret) break; } next: /* * In the vma_merge() successful mprotect-like case 8: * the next vma was merged into the current one and * the current one has not been updated yet. */ vma->vm_flags = new_flags; vma->vm_userfaultfd_ctx.ctx = ctx; skip: prev = vma; start = vma->vm_end; vma = vma->vm_next; } while (vma && vma->vm_start < end); out_unlock: up_write(&mm->mmap_sem); |
d2005e3f4 userfaultfd: don'... |
1405 |
mmput(mm); |
86039bd3b userfaultfd: add ... |
1406 1407 1408 1409 1410 1411 |
if (!ret) { /* * Now that we scanned all vmas we can already tell * userland which ioctls methods are guaranteed to * succeed on this range. */ |
ce53e8e6f userfaultfd: repo... |
1412 |
if (put_user(basic_ioctls ? UFFD_API_RANGE_IOCTLS_BASIC : |
cab350afc userfaultfd: huge... |
1413 |
UFFD_API_RANGE_IOCTLS, |
86039bd3b userfaultfd: add ... |
1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 |
&user_uffdio_register->ioctls)) ret = -EFAULT; } out: return ret; } static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, unsigned long arg) { struct mm_struct *mm = ctx->mm; struct vm_area_struct *vma, *prev, *cur; int ret; struct uffdio_range uffdio_unregister; unsigned long new_flags; bool found; unsigned long start, end, vma_end; const void __user *buf = (void __user *)arg; ret = -EFAULT; if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) goto out; ret = validate_range(mm, uffdio_unregister.start, uffdio_unregister.len); if (ret) goto out; start = uffdio_unregister.start; end = start + uffdio_unregister.len; |
d2005e3f4 userfaultfd: don'... |
1444 1445 1446 |
ret = -ENOMEM; if (!mmget_not_zero(mm)) goto out; |
86039bd3b userfaultfd: add ... |
1447 1448 |
down_write(&mm->mmap_sem); vma = find_vma_prev(mm, start, &prev); |
86039bd3b userfaultfd: add ... |
1449 1450 1451 1452 1453 1454 1455 1456 1457 |
if (!vma) goto out_unlock; /* check that there's at least one vma in the range */ ret = -EINVAL; if (vma->vm_start >= end) goto out_unlock; /* |
cab350afc userfaultfd: huge... |
1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 |
* If the first vma contains huge pages, make sure start address * is aligned to huge page size. */ if (is_vm_hugetlb_page(vma)) { unsigned long vma_hpagesize = vma_kernel_pagesize(vma); if (start & (vma_hpagesize - 1)) goto out_unlock; } /* |
86039bd3b userfaultfd: add ... |
1469 |
* Search for not compatible vmas. |
86039bd3b userfaultfd: add ... |
1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 |
*/ found = false; ret = -EINVAL; for (cur = vma; cur && cur->vm_start < end; cur = cur->vm_next) { cond_resched(); BUG_ON(!!cur->vm_userfaultfd_ctx.ctx ^ !!(cur->vm_flags & (VM_UFFD_MISSING | VM_UFFD_WP))); /* * Check not compatible vmas, not strictly required * here as not compatible vmas cannot have an * userfaultfd_ctx registered on them, but this * provides for more strict behavior to notice * unregistration errors. */ |
ba6907db6 userfaultfd: intr... |
1486 |
if (!vma_can_userfault(cur)) |
86039bd3b userfaultfd: add ... |
1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 |
goto out_unlock; found = true; } BUG_ON(!found); if (vma->vm_start < start) prev = vma; ret = 0; do { cond_resched(); |
ba6907db6 userfaultfd: intr... |
1499 |
BUG_ON(!vma_can_userfault(vma)); |
86039bd3b userfaultfd: add ... |
1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 |
/* * Nothing to do: this vma is already registered into this * userfaultfd and with the right tracking mode too. */ if (!vma->vm_userfaultfd_ctx.ctx) goto skip; if (vma->vm_start > start) start = vma->vm_start; vma_end = min(end, vma->vm_end); |
09fa5296a userfaultfd: non-... |
1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 |
if (userfaultfd_missing(vma)) { /* * Wake any concurrent pending userfault while * we unregister, so they will not hang * permanently and it avoids userland to call * UFFDIO_WAKE explicitly. */ struct userfaultfd_wake_range range; range.start = start; range.len = vma_end - start; wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range); } |
86039bd3b userfaultfd: add ... |
1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 |
new_flags = vma->vm_flags & ~(VM_UFFD_MISSING | VM_UFFD_WP); prev = vma_merge(mm, prev, start, vma_end, new_flags, vma->anon_vma, vma->vm_file, vma->vm_pgoff, vma_policy(vma), NULL_VM_UFFD_CTX); if (prev) { vma = prev; goto next; } if (vma->vm_start < start) { ret = split_vma(mm, vma, start, 1); if (ret) break; } if (vma->vm_end > end) { ret = split_vma(mm, vma, end, 0); if (ret) break; } next: /* * In the vma_merge() successful mprotect-like case 8: * the next vma was merged into the current one and * the current one has not been updated yet. */ vma->vm_flags = new_flags; vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; skip: prev = vma; start = vma->vm_end; vma = vma->vm_next; } while (vma && vma->vm_start < end); out_unlock: up_write(&mm->mmap_sem); |
d2005e3f4 userfaultfd: don'... |
1558 |
mmput(mm); |
86039bd3b userfaultfd: add ... |
1559 1560 1561 1562 1563 |
out: return ret; } /* |
ba85c702e userfaultfd: wake... |
1564 1565 |
* userfaultfd_wake may be used in combination with the * UFFDIO_*_MODE_DONTWAKE to wakeup userfaults in batches. |
86039bd3b userfaultfd: add ... |
1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 |
*/ static int userfaultfd_wake(struct userfaultfd_ctx *ctx, unsigned long arg) { int ret; struct uffdio_range uffdio_wake; struct userfaultfd_wake_range range; const void __user *buf = (void __user *)arg; ret = -EFAULT; if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake))) goto out; ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len); if (ret) goto out; range.start = uffdio_wake.start; range.len = uffdio_wake.len; /* * len == 0 means wake all and we don't want to wake all here, * so check it again to be sure. */ VM_BUG_ON(!range.len); wake_userfault(ctx, &range); ret = 0; out: return ret; } |
ad465cae9 userfaultfd: UFFD... |
1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 |
static int userfaultfd_copy(struct userfaultfd_ctx *ctx, unsigned long arg) { __s64 ret; struct uffdio_copy uffdio_copy; struct uffdio_copy __user *user_uffdio_copy; struct userfaultfd_wake_range range; user_uffdio_copy = (struct uffdio_copy __user *) arg; ret = -EFAULT; if (copy_from_user(&uffdio_copy, user_uffdio_copy, /* don't copy "copy" last field */ sizeof(uffdio_copy)-sizeof(__s64))) goto out; ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len); if (ret) goto out; /* * double check for wraparound just in case. copy_from_user() * will later check uffdio_copy.src + uffdio_copy.len to fit * in the userland range. */ ret = -EINVAL; if (uffdio_copy.src + uffdio_copy.len <= uffdio_copy.src) goto out; if (uffdio_copy.mode & ~UFFDIO_COPY_MODE_DONTWAKE) goto out; |
d2005e3f4 userfaultfd: don'... |
1627 1628 1629 1630 |
if (mmget_not_zero(ctx->mm)) { ret = mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src, uffdio_copy.len); mmput(ctx->mm); |
96333187a userfaultfd_copy:... |
1631 |
} else { |
e86b298be userfaultfd: repl... |
1632 |
return -ESRCH; |
d2005e3f4 userfaultfd: don'... |
1633 |
} |
ad465cae9 userfaultfd: UFFD... |
1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 |
if (unlikely(put_user(ret, &user_uffdio_copy->copy))) return -EFAULT; if (ret < 0) goto out; BUG_ON(!ret); /* len == 0 would wake all */ range.len = ret; if (!(uffdio_copy.mode & UFFDIO_COPY_MODE_DONTWAKE)) { range.start = uffdio_copy.dst; wake_userfault(ctx, &range); } ret = range.len == uffdio_copy.len ? 0 : -EAGAIN; out: return ret; } static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, unsigned long arg) { __s64 ret; struct uffdio_zeropage uffdio_zeropage; struct uffdio_zeropage __user *user_uffdio_zeropage; struct userfaultfd_wake_range range; user_uffdio_zeropage = (struct uffdio_zeropage __user *) arg; ret = -EFAULT; if (copy_from_user(&uffdio_zeropage, user_uffdio_zeropage, /* don't copy "zeropage" last field */ sizeof(uffdio_zeropage)-sizeof(__s64))) goto out; ret = validate_range(ctx->mm, uffdio_zeropage.range.start, uffdio_zeropage.range.len); if (ret) goto out; ret = -EINVAL; if (uffdio_zeropage.mode & ~UFFDIO_ZEROPAGE_MODE_DONTWAKE) goto out; |
d2005e3f4 userfaultfd: don'... |
1673 1674 1675 1676 |
if (mmget_not_zero(ctx->mm)) { ret = mfill_zeropage(ctx->mm, uffdio_zeropage.range.start, uffdio_zeropage.range.len); mmput(ctx->mm); |
9d95aa4ba userfaultfd_zerop... |
1677 |
} else { |
e86b298be userfaultfd: repl... |
1678 |
return -ESRCH; |
d2005e3f4 userfaultfd: don'... |
1679 |
} |
ad465cae9 userfaultfd: UFFD... |
1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 |
if (unlikely(put_user(ret, &user_uffdio_zeropage->zeropage))) return -EFAULT; if (ret < 0) goto out; /* len == 0 would wake all */ BUG_ON(!ret); range.len = ret; if (!(uffdio_zeropage.mode & UFFDIO_ZEROPAGE_MODE_DONTWAKE)) { range.start = uffdio_zeropage.range.start; wake_userfault(ctx, &range); } ret = range.len == uffdio_zeropage.range.len ? 0 : -EAGAIN; out: return ret; } |
9cd75c3cd userfaultfd: non-... |
1695 1696 1697 1698 1699 1700 1701 |
static inline unsigned int uffd_ctx_features(__u64 user_features) { /* * For the current set of features the bits just coincide */ return (unsigned int)user_features; } |
86039bd3b userfaultfd: add ... |
1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 |
/* * userland asks for a certain API version and we return which bits * and ioctl commands are implemented in this kernel for such API * version or -EINVAL if unknown. */ static int userfaultfd_api(struct userfaultfd_ctx *ctx, unsigned long arg) { struct uffdio_api uffdio_api; void __user *buf = (void __user *)arg; int ret; |
656031445 userfaultfd: non-... |
1713 |
__u64 features; |
86039bd3b userfaultfd: add ... |
1714 1715 1716 1717 1718 |
ret = -EINVAL; if (ctx->state != UFFD_STATE_WAIT_API) goto out; ret = -EFAULT; |
a9b85f941 userfaultfd: chan... |
1719 |
if (copy_from_user(&uffdio_api, buf, sizeof(uffdio_api))) |
86039bd3b userfaultfd: add ... |
1720 |
goto out; |
656031445 userfaultfd: non-... |
1721 1722 |
features = uffdio_api.features; if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES)) { |
86039bd3b userfaultfd: add ... |
1723 1724 1725 1726 1727 1728 |
memset(&uffdio_api, 0, sizeof(uffdio_api)); if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) goto out; ret = -EINVAL; goto out; } |
656031445 userfaultfd: non-... |
1729 1730 |
/* report all available features and ioctls to userland */ uffdio_api.features = UFFD_API_FEATURES; |
86039bd3b userfaultfd: add ... |
1731 1732 1733 1734 1735 |
uffdio_api.ioctls = UFFD_API_IOCTLS; ret = -EFAULT; if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) goto out; ctx->state = UFFD_STATE_RUNNING; |
656031445 userfaultfd: non-... |
1736 1737 |
/* only enable the requested features for this uffd context */ ctx->features = uffd_ctx_features(features); |
86039bd3b userfaultfd: add ... |
1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 |
ret = 0; out: return ret; } static long userfaultfd_ioctl(struct file *file, unsigned cmd, unsigned long arg) { int ret = -EINVAL; struct userfaultfd_ctx *ctx = file->private_data; |
e6485a47b userfaultfd: requ... |
1748 1749 |
if (cmd != UFFDIO_API && ctx->state == UFFD_STATE_WAIT_API) return -EINVAL; |
86039bd3b userfaultfd: add ... |
1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 |
switch(cmd) { case UFFDIO_API: ret = userfaultfd_api(ctx, arg); break; case UFFDIO_REGISTER: ret = userfaultfd_register(ctx, arg); break; case UFFDIO_UNREGISTER: ret = userfaultfd_unregister(ctx, arg); break; case UFFDIO_WAKE: ret = userfaultfd_wake(ctx, arg); break; |
ad465cae9 userfaultfd: UFFD... |
1763 1764 1765 1766 1767 1768 |
case UFFDIO_COPY: ret = userfaultfd_copy(ctx, arg); break; case UFFDIO_ZEROPAGE: ret = userfaultfd_zeropage(ctx, arg); break; |
86039bd3b userfaultfd: add ... |
1769 1770 1771 1772 1773 1774 1775 1776 |
} return ret; } #ifdef CONFIG_PROC_FS static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f) { struct userfaultfd_ctx *ctx = f->private_data; |
ac6424b98 sched/wait: Renam... |
1777 |
wait_queue_entry_t *wq; |
86039bd3b userfaultfd: add ... |
1778 1779 |
struct userfaultfd_wait_queue *uwq; unsigned long pending = 0, total = 0; |
15b726ef0 userfaultfd: opti... |
1780 |
spin_lock(&ctx->fault_pending_wqh.lock); |
2055da973 sched/wait: Disam... |
1781 |
list_for_each_entry(wq, &ctx->fault_pending_wqh.head, entry) { |
15b726ef0 userfaultfd: opti... |
1782 1783 1784 1785 |
uwq = container_of(wq, struct userfaultfd_wait_queue, wq); pending++; total++; } |
2055da973 sched/wait: Disam... |
1786 |
list_for_each_entry(wq, &ctx->fault_wqh.head, entry) { |
86039bd3b userfaultfd: add ... |
1787 |
uwq = container_of(wq, struct userfaultfd_wait_queue, wq); |
86039bd3b userfaultfd: add ... |
1788 1789 |
total++; } |
15b726ef0 userfaultfd: opti... |
1790 |
spin_unlock(&ctx->fault_pending_wqh.lock); |
86039bd3b userfaultfd: add ... |
1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 |
/* * If more protocols will be added, there will be all shown * separated by a space. Like this: * protocols: aa:... bb:... */ seq_printf(m, "pending:\t%lu total:\t%lu API:\t%Lx:%x:%Lx ", |
045098e94 userfaultfd: repo... |
1801 |
pending, total, UFFD_API, ctx->features, |
86039bd3b userfaultfd: add ... |
1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 |
UFFD_API_IOCTLS|UFFD_API_RANGE_IOCTLS); } #endif static const struct file_operations userfaultfd_fops = { #ifdef CONFIG_PROC_FS .show_fdinfo = userfaultfd_show_fdinfo, #endif .release = userfaultfd_release, .poll = userfaultfd_poll, .read = userfaultfd_read, .unlocked_ioctl = userfaultfd_ioctl, .compat_ioctl = userfaultfd_ioctl, .llseek = noop_llseek, }; |
3004ec9ca userfaultfd: allo... |
1817 1818 1819 1820 1821 1822 |
static void init_once_userfaultfd_ctx(void *mem) { struct userfaultfd_ctx *ctx = (struct userfaultfd_ctx *) mem; init_waitqueue_head(&ctx->fault_pending_wqh); init_waitqueue_head(&ctx->fault_wqh); |
9cd75c3cd userfaultfd: non-... |
1823 |
init_waitqueue_head(&ctx->event_wqh); |
3004ec9ca userfaultfd: allo... |
1824 |
init_waitqueue_head(&ctx->fd_wqh); |
2c5b7e1be userfaultfd: avoi... |
1825 |
seqcount_init(&ctx->refile_seq); |
3004ec9ca userfaultfd: allo... |
1826 |
} |
86039bd3b userfaultfd: add ... |
1827 |
/** |
9332ef9db scripts/spelling.... |
1828 |
* userfaultfd_file_create - Creates a userfaultfd file pointer. |
86039bd3b userfaultfd: add ... |
1829 1830 |
* @flags: Flags for the userfaultfd file. * |
9332ef9db scripts/spelling.... |
1831 |
* This function creates a userfaultfd file pointer, w/out installing |
86039bd3b userfaultfd: add ... |
1832 1833 1834 1835 1836 1837 |
* it into the fd table. This is useful when the userfaultfd file is * used during the initialization of data structures that require * extra setup after the userfaultfd creation. So the userfaultfd * creation is split into the file pointer creation phase, and the * file descriptor installation phase. In this way races with * userspace closing the newly installed file descriptor can be |
9332ef9db scripts/spelling.... |
1838 |
* avoided. Returns a userfaultfd file pointer, or a proper error |
86039bd3b userfaultfd: add ... |
1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 |
* pointer. */ static struct file *userfaultfd_file_create(int flags) { struct file *file; struct userfaultfd_ctx *ctx; BUG_ON(!current->mm); /* Check the UFFD_* constants for consistency. */ BUILD_BUG_ON(UFFD_CLOEXEC != O_CLOEXEC); BUILD_BUG_ON(UFFD_NONBLOCK != O_NONBLOCK); file = ERR_PTR(-EINVAL); if (flags & ~UFFD_SHARED_FCNTL_FLAGS) goto out; file = ERR_PTR(-ENOMEM); |
3004ec9ca userfaultfd: allo... |
1857 |
ctx = kmem_cache_alloc(userfaultfd_ctx_cachep, GFP_KERNEL); |
86039bd3b userfaultfd: add ... |
1858 1859 1860 1861 |
if (!ctx) goto out; atomic_set(&ctx->refcount, 1); |
86039bd3b userfaultfd: add ... |
1862 |
ctx->flags = flags; |
9cd75c3cd userfaultfd: non-... |
1863 |
ctx->features = 0; |
86039bd3b userfaultfd: add ... |
1864 1865 1866 1867 |
ctx->state = UFFD_STATE_WAIT_API; ctx->released = false; ctx->mm = current->mm; /* prevent the mm struct to be freed */ |
f1f100764 mm: add new mmgra... |
1868 |
mmgrab(ctx->mm); |
86039bd3b userfaultfd: add ... |
1869 1870 1871 |
file = anon_inode_getfile("[userfaultfd]", &userfaultfd_fops, ctx, O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS)); |
c03e946fd userfaultfd: add ... |
1872 |
if (IS_ERR(file)) { |
d2005e3f4 userfaultfd: don'... |
1873 |
mmdrop(ctx->mm); |
3004ec9ca userfaultfd: allo... |
1874 |
kmem_cache_free(userfaultfd_ctx_cachep, ctx); |
c03e946fd userfaultfd: add ... |
1875 |
} |
86039bd3b userfaultfd: add ... |
1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 |
out: return file; } SYSCALL_DEFINE1(userfaultfd, int, flags) { int fd, error; struct file *file; error = get_unused_fd_flags(flags & UFFD_SHARED_FCNTL_FLAGS); if (error < 0) return error; fd = error; file = userfaultfd_file_create(flags); if (IS_ERR(file)) { error = PTR_ERR(file); goto err_put_unused_fd; } fd_install(fd, file); return fd; err_put_unused_fd: put_unused_fd(fd); return error; } |
3004ec9ca userfaultfd: allo... |
1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 |
static int __init userfaultfd_init(void) { userfaultfd_ctx_cachep = kmem_cache_create("userfaultfd_ctx_cache", sizeof(struct userfaultfd_ctx), 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, init_once_userfaultfd_ctx); return 0; } __initcall(userfaultfd_init); |