[PATCH 21/23] userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation
This implements mcopy_atomic and mfill_zeropage that are the lowlevel VM methods that are invoked respectively by the UFFDIO_COPY and UFFDIO_ZEROPAGE userfaultfd commands. Signed-off-by: Andrea Arcangeli --- include/linux/userfaultfd_k.h | 6 + mm/Makefile | 1 + mm/userfaultfd.c | 269 ++ 3 files changed, 276 insertions(+) create mode 100644 mm/userfaultfd.c diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index e1e4360..587480a 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -30,6 +30,12 @@ extern int handle_userfault(struct vm_area_struct *vma, unsigned long address, unsigned int flags, unsigned long reason); +extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, + unsigned long src_start, unsigned long len); +extern ssize_t mfill_zeropage(struct mm_struct *dst_mm, + unsigned long dst_start, + unsigned long len); + /* mm helpers */ static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma, struct vm_userfaultfd_ctx vm_ctx) diff --git a/mm/Makefile b/mm/Makefile index 98c4eae..b424d5e 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -78,3 +78,4 @@ obj-$(CONFIG_CMA) += cma.o obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o +obj-$(CONFIG_USERFAULTFD) += userfaultfd.o diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c new file mode 100644 index 000..c54c761 --- /dev/null +++ b/mm/userfaultfd.c @@ -0,0 +1,269 @@ +/* + * mm/userfaultfd.c + * + * 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. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include "internal.h" + +static int mcopy_atomic_pte(struct mm_struct *dst_mm, + pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, + unsigned long src_addr) +{ + struct mem_cgroup *memcg; + pte_t _dst_pte, *dst_pte; + spinlock_t *ptl; + struct page *page; + void *page_kaddr; + int ret; + + ret = -ENOMEM; + page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); + if (!page) + goto out; + + page_kaddr = kmap(page); + ret = -EFAULT; + if (copy_from_user(page_kaddr, (const void __user *) src_addr, + PAGE_SIZE)) + goto out_kunmap_release; + kunmap(page); + + /* +* The memory barrier inside __SetPageUptodate makes sure that +* preceeding stores to the page contents become visible before +* the set_pte_at() write. +*/ + __SetPageUptodate(page); + + ret = -ENOMEM; + if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, )) + goto out_release; + + _dst_pte = mk_pte(page, dst_vma->vm_page_prot); + if (dst_vma->vm_flags & VM_WRITE) + _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte)); + + ret = -EEXIST; + dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, ); + if (!pte_none(*dst_pte)) + goto out_release_uncharge_unlock; + + inc_mm_counter(dst_mm, MM_ANONPAGES); + page_add_new_anon_rmap(page, dst_vma, dst_addr); + mem_cgroup_commit_charge(page, memcg, false); + lru_cache_add_active_or_unevictable(page, dst_vma); + + set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); + + /* No need to invalidate - it was non-present before */ + update_mmu_cache(dst_vma, dst_addr, dst_pte); + + pte_unmap_unlock(dst_pte, ptl); + ret = 0; +out: + return ret; +out_release_uncharge_unlock: + pte_unmap_unlock(dst_pte, ptl); + mem_cgroup_cancel_charge(page, memcg); +out_release: + page_cache_release(page); + goto out; +out_kunmap_release: + kunmap(page); + goto out_release; +} + +static int mfill_zeropage_pte(struct mm_struct *dst_mm, + pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr) +{ + pte_t _dst_pte, *dst_pte; + spinlock_t *ptl; + int ret; + + _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), +dst_vma->vm_page_prot)); + ret = -EEXIST; + dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, ); + if (!pte_none(*dst_pte)) + goto out_unlock; + set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); + /* No need to invalidate
[PATCH 21/23] userfaultfd: mcopy_atomic|mfill_zeropage: UFFDIO_COPY|UFFDIO_ZEROPAGE preparation
This implements mcopy_atomic and mfill_zeropage that are the lowlevel VM methods that are invoked respectively by the UFFDIO_COPY and UFFDIO_ZEROPAGE userfaultfd commands. Signed-off-by: Andrea Arcangeli aarca...@redhat.com --- include/linux/userfaultfd_k.h | 6 + mm/Makefile | 1 + mm/userfaultfd.c | 269 ++ 3 files changed, 276 insertions(+) create mode 100644 mm/userfaultfd.c diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index e1e4360..587480a 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -30,6 +30,12 @@ extern int handle_userfault(struct vm_area_struct *vma, unsigned long address, unsigned int flags, unsigned long reason); +extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, + unsigned long src_start, unsigned long len); +extern ssize_t mfill_zeropage(struct mm_struct *dst_mm, + unsigned long dst_start, + unsigned long len); + /* mm helpers */ static inline bool is_mergeable_vm_userfaultfd_ctx(struct vm_area_struct *vma, struct vm_userfaultfd_ctx vm_ctx) diff --git a/mm/Makefile b/mm/Makefile index 98c4eae..b424d5e 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -78,3 +78,4 @@ obj-$(CONFIG_CMA) += cma.o obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o obj-$(CONFIG_CMA_DEBUGFS) += cma_debug.o +obj-$(CONFIG_USERFAULTFD) += userfaultfd.o diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c new file mode 100644 index 000..c54c761 --- /dev/null +++ b/mm/userfaultfd.c @@ -0,0 +1,269 @@ +/* + * mm/userfaultfd.c + * + * 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. + */ + +#include linux/mm.h +#include linux/pagemap.h +#include linux/rmap.h +#include linux/swap.h +#include linux/swapops.h +#include linux/userfaultfd_k.h +#include linux/mmu_notifier.h +#include asm/tlbflush.h +#include internal.h + +static int mcopy_atomic_pte(struct mm_struct *dst_mm, + pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr, + unsigned long src_addr) +{ + struct mem_cgroup *memcg; + pte_t _dst_pte, *dst_pte; + spinlock_t *ptl; + struct page *page; + void *page_kaddr; + int ret; + + ret = -ENOMEM; + page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr); + if (!page) + goto out; + + page_kaddr = kmap(page); + ret = -EFAULT; + if (copy_from_user(page_kaddr, (const void __user *) src_addr, + PAGE_SIZE)) + goto out_kunmap_release; + kunmap(page); + + /* +* The memory barrier inside __SetPageUptodate makes sure that +* preceeding stores to the page contents become visible before +* the set_pte_at() write. +*/ + __SetPageUptodate(page); + + ret = -ENOMEM; + if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, memcg)) + goto out_release; + + _dst_pte = mk_pte(page, dst_vma-vm_page_prot); + if (dst_vma-vm_flags VM_WRITE) + _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte)); + + ret = -EEXIST; + dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, ptl); + if (!pte_none(*dst_pte)) + goto out_release_uncharge_unlock; + + inc_mm_counter(dst_mm, MM_ANONPAGES); + page_add_new_anon_rmap(page, dst_vma, dst_addr); + mem_cgroup_commit_charge(page, memcg, false); + lru_cache_add_active_or_unevictable(page, dst_vma); + + set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte); + + /* No need to invalidate - it was non-present before */ + update_mmu_cache(dst_vma, dst_addr, dst_pte); + + pte_unmap_unlock(dst_pte, ptl); + ret = 0; +out: + return ret; +out_release_uncharge_unlock: + pte_unmap_unlock(dst_pte, ptl); + mem_cgroup_cancel_charge(page, memcg); +out_release: + page_cache_release(page); + goto out; +out_kunmap_release: + kunmap(page); + goto out_release; +} + +static int mfill_zeropage_pte(struct mm_struct *dst_mm, + pmd_t *dst_pmd, + struct vm_area_struct *dst_vma, + unsigned long dst_addr) +{ + pte_t _dst_pte, *dst_pte; + spinlock_t *ptl; + int ret; + + _dst_pte = pte_mkspecial(pfn_pte(my_zero_pfn(dst_addr), +dst_vma-vm_page_prot)); + ret = -EEXIST; + dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, ptl); + if