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Shutemov" , Maya Gokhale , Johannes Weiner , Marty McFadden , Denis Plotnikov , Hugh Dickins , "Dr . David Alan Gilbert" , Jerome Glisse Subject: [PATCH v6 05/19] userfaultfd: wp: add UFFDIO_COPY_MODE_WP Date: Thu, 20 Feb 2020 11:30:58 -0500 Message-Id: <20200220163112.11409-6-peterx@redhat.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200220163112.11409-1-peterx@redhat.com> References: <20200220163112.11409-1-peterx@redhat.com> MIME-Version: 1.0 X-MC-Unique: wmrXovNOOva_Kcv7r-Jmmw-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Andrea Arcangeli This allows UFFDIO_COPY to map pages write-protected. Signed-off-by: Andrea Arcangeli [peterx: switch to VM_WARN_ON_ONCE in mfill_atomic_pte; add brackets around "dst_vma->vm_flags & VM_WRITE"; fix wordings in comments and commit messages] Reviewed-by: Jerome Glisse Reviewed-by: Mike Rapoport Signed-off-by: Peter Xu --- fs/userfaultfd.c | 5 +++-- include/linux/userfaultfd_k.h | 2 +- include/uapi/linux/userfaultfd.h | 11 +++++----- mm/userfaultfd.c | 36 ++++++++++++++++++++++---------- 4 files changed, 35 insertions(+), 19 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 703c1c3faa6e..c49bef505775 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1724,11 +1724,12 @@ static int userfaultfd_copy(struct userfaultfd_ctx = *ctx, =09ret =3D -EINVAL; =09if (uffdio_copy.src + uffdio_copy.len <=3D uffdio_copy.src) =09=09goto out; -=09if (uffdio_copy.mode & ~UFFDIO_COPY_MODE_DONTWAKE) +=09if (uffdio_copy.mode & ~(UFFDIO_COPY_MODE_DONTWAKE|UFFDIO_COPY_MODE_WP)= ) =09=09goto out; =09if (mmget_not_zero(ctx->mm)) { =09=09ret =3D mcopy_atomic(ctx->mm, uffdio_copy.dst, uffdio_copy.src, -=09=09=09=09 uffdio_copy.len, &ctx->mmap_changing); +=09=09=09=09 uffdio_copy.len, &ctx->mmap_changing, +=09=09=09=09 uffdio_copy.mode); =09=09mmput(ctx->mm); =09} else { =09=09return -ESRCH; diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h index 7b91b76aac58..dcd33172b728 100644 --- a/include/linux/userfaultfd_k.h +++ b/include/linux/userfaultfd_k.h @@ -36,7 +36,7 @@ extern vm_fault_t handle_userfault(struct vm_fault *vmf, = unsigned long reason); =20 extern ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_st= art, =09=09=09 unsigned long src_start, unsigned long len, -=09=09=09 bool *mmap_changing); +=09=09=09 bool *mmap_changing, __u64 mode); extern ssize_t mfill_zeropage(struct mm_struct *dst_mm, =09=09=09 unsigned long dst_start, =09=09=09 unsigned long len, diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaul= tfd.h index 48f1a7c2f1f0..340f23bc251d 100644 --- a/include/uapi/linux/userfaultfd.h +++ b/include/uapi/linux/userfaultfd.h @@ -203,13 +203,14 @@ struct uffdio_copy { =09__u64 dst; =09__u64 src; =09__u64 len; +#define UFFDIO_COPY_MODE_DONTWAKE=09=09((__u64)1<<0) =09/* -=09 * There will be a wrprotection flag later that allows to map -=09 * pages wrprotected on the fly. And such a flag will be -=09 * available if the wrprotection ioctl are implemented for the -=09 * range according to the uffdio_register.ioctls. +=09 * UFFDIO_COPY_MODE_WP will map the page write protected on +=09 * the fly. UFFDIO_COPY_MODE_WP is available only if the +=09 * write protected ioctl is implemented for the range +=09 * according to the uffdio_register.ioctls. =09 */ -#define UFFDIO_COPY_MODE_DONTWAKE=09=09((__u64)1<<0) +#define UFFDIO_COPY_MODE_WP=09=09=09((__u64)1<<1) =09__u64 mode; =20 =09/* diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 1b0d7abad1d4..44a5e5429fac 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -53,7 +53,8 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm, =09=09=09 struct vm_area_struct *dst_vma, =09=09=09 unsigned long dst_addr, =09=09=09 unsigned long src_addr, -=09=09=09 struct page **pagep) +=09=09=09 struct page **pagep, +=09=09=09 bool wp_copy) { =09struct mem_cgroup *memcg; =09pte_t _dst_pte, *dst_pte; @@ -99,9 +100,9 @@ static int mcopy_atomic_pte(struct mm_struct *dst_mm, =09if (mem_cgroup_try_charge(page, dst_mm, GFP_KERNEL, &memcg, false)) =09=09goto out_release; =20 -=09_dst_pte =3D mk_pte(page, dst_vma->vm_page_prot); -=09if (dst_vma->vm_flags & VM_WRITE) -=09=09_dst_pte =3D pte_mkwrite(pte_mkdirty(_dst_pte)); +=09_dst_pte =3D pte_mkdirty(mk_pte(page, dst_vma->vm_page_prot)); +=09if ((dst_vma->vm_flags & VM_WRITE) && !wp_copy) +=09=09_dst_pte =3D pte_mkwrite(_dst_pte); =20 =09dst_pte =3D pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl); =09if (dst_vma->vm_file) { @@ -408,7 +409,8 @@ static __always_inline ssize_t mfill_atomic_pte(struct = mm_struct *dst_mm, =09=09=09=09=09=09unsigned long dst_addr, =09=09=09=09=09=09unsigned long src_addr, =09=09=09=09=09=09struct page **page, -=09=09=09=09=09=09bool zeropage) +=09=09=09=09=09=09bool zeropage, +=09=09=09=09=09=09bool wp_copy) { =09ssize_t err; =20 @@ -425,11 +427,13 @@ static __always_inline ssize_t mfill_atomic_pte(struc= t mm_struct *dst_mm, =09if (!(dst_vma->vm_flags & VM_SHARED)) { =09=09if (!zeropage) =09=09=09err =3D mcopy_atomic_pte(dst_mm, dst_pmd, dst_vma, -=09=09=09=09=09 dst_addr, src_addr, page); +=09=09=09=09=09 dst_addr, src_addr, page, +=09=09=09=09=09 wp_copy); =09=09else =09=09=09err =3D mfill_zeropage_pte(dst_mm, dst_pmd, =09=09=09=09=09=09 dst_vma, dst_addr); =09} else { +=09=09VM_WARN_ON_ONCE(wp_copy); =09=09if (!zeropage) =09=09=09err =3D shmem_mcopy_atomic_pte(dst_mm, dst_pmd, =09=09=09=09=09=09 dst_vma, dst_addr, @@ -447,7 +451,8 @@ static __always_inline ssize_t __mcopy_atomic(struct mm= _struct *dst_mm, =09=09=09=09=09 unsigned long src_start, =09=09=09=09=09 unsigned long len, =09=09=09=09=09 bool zeropage, -=09=09=09=09=09 bool *mmap_changing) +=09=09=09=09=09 bool *mmap_changing, +=09=09=09=09=09 __u64 mode) { =09struct vm_area_struct *dst_vma; =09ssize_t err; @@ -455,6 +460,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm= _struct *dst_mm, =09unsigned long src_addr, dst_addr; =09long copied; =09struct page *page; +=09bool wp_copy; =20 =09/* =09 * Sanitize the command parameters: @@ -500,6 +506,14 @@ static __always_inline ssize_t __mcopy_atomic(struct m= m_struct *dst_mm, =09 dst_vma->vm_flags & VM_SHARED)) =09=09goto out_unlock; =20 +=09/* +=09 * validate 'mode' now that we know the dst_vma: don't allow +=09 * a wrprotect copy if the userfaultfd didn't register as WP. +=09 */ +=09wp_copy =3D mode & UFFDIO_COPY_MODE_WP; +=09if (wp_copy && !(dst_vma->vm_flags & VM_UFFD_WP)) +=09=09goto out_unlock; + =09/* =09 * If this is a HUGETLB vma, pass off to appropriate routine =09 */ @@ -555,7 +569,7 @@ static __always_inline ssize_t __mcopy_atomic(struct mm= _struct *dst_mm, =09=09BUG_ON(pmd_trans_huge(*dst_pmd)); =20 =09=09err =3D mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, -=09=09=09=09 src_addr, &page, zeropage); +=09=09=09=09 src_addr, &page, zeropage, wp_copy); =09=09cond_resched(); =20 =09=09if (unlikely(err =3D=3D -ENOENT)) { @@ -602,14 +616,14 @@ static __always_inline ssize_t __mcopy_atomic(struct = mm_struct *dst_mm, =20 ssize_t mcopy_atomic(struct mm_struct *dst_mm, unsigned long dst_start, =09=09 unsigned long src_start, unsigned long len, -=09=09 bool *mmap_changing) +=09=09 bool *mmap_changing, __u64 mode) { =09return __mcopy_atomic(dst_mm, dst_start, src_start, len, false, -=09=09=09 mmap_changing); +=09=09=09 mmap_changing, mode); } =20 ssize_t mfill_zeropage(struct mm_struct *dst_mm, unsigned long start, =09=09 unsigned long len, bool *mmap_changing) { -=09return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing); +=09return __mcopy_atomic(dst_mm, start, 0, len, true, mmap_changing, 0); } --=20 2.24.1