Received: by 2002:aa6:c781:0:b0:139:2837:6657 with SMTP id u1csp1539713lkq; Fri, 3 Sep 2021 09:16:39 -0700 (PDT) X-Google-Smtp-Source: ABdhPJyfM/W+FXQVRKMERIG5WelRIxhl2GXyv55ANgqrW9jRDSp9usrSpy5I6lhw+KOpIO8CrN/T X-Received: by 2002:a02:866b:: with SMTP id e98mr3285056jai.48.1630685799281; Fri, 03 Sep 2021 09:16:39 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1630685799; cv=none; d=google.com; s=arc-20160816; b=0Mn/tqo9hv4YhMDCqInYeVx9B38IyhxpAbi2qZXT+X4VwIMl9ogZPZf0ZxmABJUSac lqi4DJSmPUmI7pb8Q6yFn7vBWBzp2wpBEt80NDw5RSiuDiKAxtxy1r9Yk01+5oxOwLUq iu+xrUXxFEYK8OYP4RGSBNpxUHj3az0DhaGr9bsRhxzhSyiCgVAvWl8hScEkRNb7Iu4e 21pU1cSdZvt1AVR5fEkcYMokF2eybKzl/jGStRf12bg/P0KJCuSBYypUaenf9s5hk8VM 8VOLaWgg1bzmPJMYLZl0T3vrFkUT9ht8jxbbAobXEqpwJ6j3NsMIhce43vpSmn32xnZp yEqg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:cc:to:subject :message-id:date:from:reply-to:in-reply-to:references:mime-version :dkim-signature; bh=zZZ87vz+C4ZG1Hl87mUuE3qkrU78d+Yyq+IOBIIOZx8=; b=oTC0EBp+8GCVbkAT5+8nfOVuULYd1iGAyJS3EWu4GSxJhb6fQSX1LtkT3wvDX98VOT xynH/tKrGpCLxSEwDAcT6Z5hBS5wfPAUepN28URjIcA3qS4rxvRXKwL7ZFdS0TYF5gJZ 22FhVXJBYPzjsvVnibBOGtog9C6XDbZ7VDSpdjYnYPWrDMrieKOXDD4dSPOkUCdAD+N9 PKNOyK2c7BMe9T+wH8epqgebDDMuImlOFq8DxJhHYHpiPHXrvZGuGHLe1sKuI6hJsjdc M4fdvnxgZIw5F4bxviFIpMYlWfhVm+fAg0ooCQU6JDTKYJOodN7hiWXQKGBoMiv+mAY8 +e5g== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=mPztU7i+; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id g1si6211685ile.140.2021.09.03.09.16.25; Fri, 03 Sep 2021 09:16:39 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=mPztU7i+; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349502AbhICO6F (ORCPT + 99 others); Fri, 3 Sep 2021 10:58:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233407AbhICO6E (ORCPT ); Fri, 3 Sep 2021 10:58:04 -0400 Received: from mail-qk1-x731.google.com (mail-qk1-x731.google.com [IPv6:2607:f8b0:4864:20::731]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7202BC061575; Fri, 3 Sep 2021 07:57:04 -0700 (PDT) Received: by mail-qk1-x731.google.com with SMTP id a10so6018468qka.12; Fri, 03 Sep 2021 07:57:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:references:in-reply-to:reply-to:from:date:message-id :subject:to:cc:content-transfer-encoding; bh=zZZ87vz+C4ZG1Hl87mUuE3qkrU78d+Yyq+IOBIIOZx8=; b=mPztU7i+zjQ6o0IVLJTsGSi5DqnRPp4nS2m7r/OaOEQmwK7KPEO+Kcw9VA9JRhl9Ap vB6CYN3iPYv7kiulki49woN3h2mtE/0OhOALqdYnBCZD39z0TYBFABJJjQcpWPe2oNiF //chMvVB2LQkgs6Ge0uS7nhWHENEG1AzqwtjW4iF3c7R84OjvEJ642xG3CliHVWtGSQF nIqOeQK701kEZmBsUlpdH3lCVQWrPcb4hOu5D/NE2rt/DYHzQoXVBwJ0kXTPEhN7zpP5 fhO2UqOvn/X8R5UkHm7tEysYG8ZulcqKrXFDnCxH2DGJcmLQPxXgDBkneNT4sLrMpnrL iw5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:reply-to :from:date:message-id:subject:to:cc:content-transfer-encoding; bh=zZZ87vz+C4ZG1Hl87mUuE3qkrU78d+Yyq+IOBIIOZx8=; b=ABYDBVxt8EwCDBjuCQsbkBS9HWqrMZTkF5KZyTMMXeD9QIq70fCDGgKfjhfDAQ8Nvj ro7bfxOh4PHtI4FbWu7/jJ1+MvGovnvUPidiRDF6aV1vyGwl8iXI54slTFFKJbYk8/G6 t2IAHcjal0aqmq4sQP/AtmatB3fT2ZtkvSTfGZO+X6TRdZl+rPpE+WPuUSFqLvNOs+Og wnFL8ce2QA3Cs5OuyjEtEmBG/YDQ2/s7RVDzwiRf+3Lz4KMAFciw2kdBIGzFYu6zR4un xC4PP86mQRS9foF4SqICxiEMXRSuUJ1hev+2gvxbJps725LK4BX5e3kSkDacQXuy91LT 4GpA== X-Gm-Message-State: AOAM5305wqbq/PXPD48/aBHvEmfREpNPsgebf7QOJwMaVRnwGlgJG0cT oiy+DZBSVunWzmjGridSe0MN1BHF00wOyeh5b3I= X-Received: by 2002:a05:620a:2844:: with SMTP id h4mr3864553qkp.388.1630681023513; Fri, 03 Sep 2021 07:57:03 -0700 (PDT) MIME-Version: 1.0 References: <20210827164926.1726765-1-agruenba@redhat.com> <20210827164926.1726765-4-agruenba@redhat.com> In-Reply-To: <20210827164926.1726765-4-agruenba@redhat.com> Reply-To: fdmanana@gmail.com From: Filipe Manana Date: Fri, 3 Sep 2021 15:56:27 +0100 Message-ID: Subject: Re: [PATCH v7 03/19] gup: Turn fault_in_pages_{readable,writeable} into fault_in_{readable,writeable} To: Andreas Gruenbacher Cc: Linus Torvalds , Alexander Viro , Christoph Hellwig , "Darrick J. Wong" , Jan Kara , Matthew Wilcox , cluster-devel@redhat.com, linux-fsdevel , Linux Kernel Mailing List , ocfs2-devel@oss.oracle.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 27, 2021 at 5:52 PM Andreas Gruenbacher w= rote: > > Turn fault_in_pages_{readable,writeable} into versions that return the > number of bytes not faulted in (similar to copy_to_user) instead of > returning a non-zero value when any of the requested pages couldn't be > faulted in. This supports the existing users that require all pages to > be faulted in as well as new users that are happy if any pages can be > faulted in at all. > > Neither of these functions is entirely trivial and it doesn't seem > useful to inline them, so move them to mm/gup.c. > > Rename the functions to fault_in_{readable,writeable} to make sure that > this change doesn't silently break things. > > Signed-off-by: Andreas Gruenbacher > --- > arch/powerpc/kernel/kvm.c | 3 +- > arch/powerpc/kernel/signal_32.c | 4 +- > arch/powerpc/kernel/signal_64.c | 2 +- > arch/x86/kernel/fpu/signal.c | 7 ++- > drivers/gpu/drm/armada/armada_gem.c | 7 ++- > fs/btrfs/ioctl.c | 5 +- > include/linux/pagemap.h | 57 ++--------------------- > lib/iov_iter.c | 10 ++-- > mm/filemap.c | 2 +- > mm/gup.c | 72 +++++++++++++++++++++++++++++ > 10 files changed, 93 insertions(+), 76 deletions(-) > > diff --git a/arch/powerpc/kernel/kvm.c b/arch/powerpc/kernel/kvm.c > index d89cf802d9aa..6568823cf306 100644 > --- a/arch/powerpc/kernel/kvm.c > +++ b/arch/powerpc/kernel/kvm.c > @@ -669,7 +669,8 @@ static void __init kvm_use_magic_page(void) > on_each_cpu(kvm_map_magic_page, &features, 1); > > /* Quick self-test to see if the mapping works */ > - if (fault_in_pages_readable((const char *)KVM_MAGIC_PAGE, sizeof(= u32))) { > + if (fault_in_readable((const char __user *)KVM_MAGIC_PAGE, > + sizeof(u32))) { > kvm_patching_worked =3D false; > return; > } > diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal= _32.c > index 0608581967f0..38c3eae40c14 100644 > --- a/arch/powerpc/kernel/signal_32.c > +++ b/arch/powerpc/kernel/signal_32.c > @@ -1048,7 +1048,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user= *, old_ctx, > if (new_ctx =3D=3D NULL) > return 0; > if (!access_ok(new_ctx, ctx_size) || > - fault_in_pages_readable((u8 __user *)new_ctx, ctx_size)) > + fault_in_readable((char __user *)new_ctx, ctx_size)) > return -EFAULT; > > /* > @@ -1237,7 +1237,7 @@ SYSCALL_DEFINE3(debug_setcontext, struct ucontext _= _user *, ctx, > #endif > > if (!access_ok(ctx, sizeof(*ctx)) || > - fault_in_pages_readable((u8 __user *)ctx, sizeof(*ctx))) > + fault_in_readable((char __user *)ctx, sizeof(*ctx))) > return -EFAULT; > > /* > diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal= _64.c > index 1831bba0582e..9f471b4a11e3 100644 > --- a/arch/powerpc/kernel/signal_64.c > +++ b/arch/powerpc/kernel/signal_64.c > @@ -688,7 +688,7 @@ SYSCALL_DEFINE3(swapcontext, struct ucontext __user *= , old_ctx, > if (new_ctx =3D=3D NULL) > return 0; > if (!access_ok(new_ctx, ctx_size) || > - fault_in_pages_readable((u8 __user *)new_ctx, ctx_size)) > + fault_in_readable((char __user *)new_ctx, ctx_size)) > return -EFAULT; > > /* > diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c > index 445c57c9c539..ba6bdec81603 100644 > --- a/arch/x86/kernel/fpu/signal.c > +++ b/arch/x86/kernel/fpu/signal.c > @@ -205,7 +205,7 @@ int copy_fpstate_to_sigframe(void __user *buf, void _= _user *buf_fx, int size) > fpregs_unlock(); > > if (ret) { > - if (!fault_in_pages_writeable(buf_fx, fpu_user_xstate_siz= e)) > + if (!fault_in_writeable(buf_fx, fpu_user_xstate_size)) > goto retry; > return -EFAULT; > } > @@ -278,10 +278,9 @@ static int restore_fpregs_from_user(void __user *buf= , u64 xrestore, > if (ret !=3D -EFAULT) > return -EINVAL; > > - ret =3D fault_in_pages_readable(buf, size); > - if (!ret) > + if (!fault_in_readable(buf, size)) > goto retry; > - return ret; > + return -EFAULT; > } > > /* > diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada= /armada_gem.c > index 21909642ee4c..8fbb25913327 100644 > --- a/drivers/gpu/drm/armada/armada_gem.c > +++ b/drivers/gpu/drm/armada/armada_gem.c > @@ -336,7 +336,7 @@ int armada_gem_pwrite_ioctl(struct drm_device *dev, v= oid *data, > struct drm_armada_gem_pwrite *args =3D data; > struct armada_gem_object *dobj; > char __user *ptr; > - int ret; > + int ret =3D 0; > > DRM_DEBUG_DRIVER("handle %u off %u size %u ptr 0x%llx\n", > args->handle, args->offset, args->size, args->ptr); > @@ -349,9 +349,8 @@ int armada_gem_pwrite_ioctl(struct drm_device *dev, v= oid *data, > if (!access_ok(ptr, args->size)) > return -EFAULT; > > - ret =3D fault_in_pages_readable(ptr, args->size); > - if (ret) > - return ret; > + if (fault_in_readable(ptr, args->size)) > + return -EFAULT; > > dobj =3D armada_gem_object_lookup(file, args->handle); > if (dobj =3D=3D NULL) > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c > index 0ba98e08a029..9233ecc31e2e 100644 > --- a/fs/btrfs/ioctl.c > +++ b/fs/btrfs/ioctl.c > @@ -2244,9 +2244,8 @@ static noinline int search_ioctl(struct inode *inod= e, > key.offset =3D sk->min_offset; > > while (1) { > - ret =3D fault_in_pages_writeable(ubuf + sk_offset, > - *buf_size - sk_offset); > - if (ret) > + ret =3D -EFAULT; > + if (fault_in_writeable(ubuf + sk_offset, *buf_size - sk_o= ffset)) > break; > > ret =3D btrfs_search_forward(root, &key, path, sk->min_tr= ansid); > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index ed02aa522263..7c9edc9694d9 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -734,61 +734,10 @@ int wait_on_page_private_2_killable(struct page *pa= ge); > extern void add_page_wait_queue(struct page *page, wait_queue_entry_t *w= aiter); > > /* > - * Fault everything in given userspace address range in. > + * Fault in userspace address range. > */ > -static inline int fault_in_pages_writeable(char __user *uaddr, int size) > -{ > - char __user *end =3D uaddr + size - 1; > - > - if (unlikely(size =3D=3D 0)) > - return 0; > - > - if (unlikely(uaddr > end)) > - return -EFAULT; > - /* > - * Writing zeroes into userspace here is OK, because we know that= if > - * the zero gets there, we'll be overwriting it. > - */ > - do { > - if (unlikely(__put_user(0, uaddr) !=3D 0)) > - return -EFAULT; > - uaddr +=3D PAGE_SIZE; > - } while (uaddr <=3D end); > - > - /* Check whether the range spilled into the next page. */ > - if (((unsigned long)uaddr & PAGE_MASK) =3D=3D > - ((unsigned long)end & PAGE_MASK)) > - return __put_user(0, end); > - > - return 0; > -} > - > -static inline int fault_in_pages_readable(const char __user *uaddr, int = size) > -{ > - volatile char c; > - const char __user *end =3D uaddr + size - 1; > - > - if (unlikely(size =3D=3D 0)) > - return 0; > - > - if (unlikely(uaddr > end)) > - return -EFAULT; > - > - do { > - if (unlikely(__get_user(c, uaddr) !=3D 0)) > - return -EFAULT; > - uaddr +=3D PAGE_SIZE; > - } while (uaddr <=3D end); > - > - /* Check whether the range spilled into the next page. */ > - if (((unsigned long)uaddr & PAGE_MASK) =3D=3D > - ((unsigned long)end & PAGE_MASK)) { > - return __get_user(c, end); > - } > - > - (void)c; > - return 0; > -} > +size_t fault_in_writeable(char __user *uaddr, size_t size); > +size_t fault_in_readable(const char __user *uaddr, size_t size); > > int add_to_page_cache_locked(struct page *page, struct address_space *ma= pping, > pgoff_t index, gfp_t gfp_mask); > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index 25dfc48536d7..069cedd9d7b4 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -191,7 +191,7 @@ static size_t copy_page_to_iter_iovec(struct page *pa= ge, size_t offset, size_t b > buf =3D iov->iov_base + skip; > copy =3D min(bytes, iov->iov_len - skip); > > - if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_writeable(buf, = copy)) { > + if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_writeable(buf, copy))= { > kaddr =3D kmap_atomic(page); > from =3D kaddr + offset; > > @@ -275,7 +275,7 @@ static size_t copy_page_from_iter_iovec(struct page *= page, size_t offset, size_t > buf =3D iov->iov_base + skip; > copy =3D min(bytes, iov->iov_len - skip); > > - if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_pages_readable(buf, c= opy)) { > + if (IS_ENABLED(CONFIG_HIGHMEM) && !fault_in_readable(buf, copy)) = { > kaddr =3D kmap_atomic(page); > to =3D kaddr + offset; > > @@ -446,13 +446,11 @@ int iov_iter_fault_in_readable(const struct iov_ite= r *i, size_t bytes) > bytes =3D i->count; > for (p =3D i->iov, skip =3D i->iov_offset; bytes; p++, sk= ip =3D 0) { > size_t len =3D min(bytes, p->iov_len - skip); > - int err; > > if (unlikely(!len)) > continue; > - err =3D fault_in_pages_readable(p->iov_base + ski= p, len); > - if (unlikely(err)) > - return err; > + if (fault_in_readable(p->iov_base + skip, len)) > + return -EFAULT; > bytes -=3D len; > } > } > diff --git a/mm/filemap.c b/mm/filemap.c > index d1458ecf2f51..4dec3bc7752e 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -88,7 +88,7 @@ > * ->lock_page (access_process_vm) > * > * ->i_mutex (generic_perform_write) > - * ->mmap_lock (fault_in_pages_readable->do_page_fault) > + * ->mmap_lock (fault_in_readable->do_page_fault) > * > * bdi->wb.list_lock > * sb_lock (fs/fs-writeback.c) > diff --git a/mm/gup.c b/mm/gup.c > index b94717977d17..0cf47955e5a1 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1672,6 +1672,78 @@ static long __get_user_pages_locked(struct mm_stru= ct *mm, unsigned long start, > } > #endif /* !CONFIG_MMU */ > > +/** > + * fault_in_writeable - fault in userspace address range for writing > + * @uaddr: start of address range > + * @size: size of address range > + * > + * Returns the number of bytes not faulted in (like copy_to_user() and > + * copy_from_user()). > + */ > +size_t fault_in_writeable(char __user *uaddr, size_t size) > +{ > + char __user *start =3D uaddr, *end; > + > + if (unlikely(size =3D=3D 0)) > + return 0; > + if (!PAGE_ALIGNED(uaddr)) { > + if (unlikely(__put_user(0, uaddr) !=3D 0)) > + return size; > + uaddr =3D (char __user *)PAGE_ALIGN((unsigned long)uaddr)= ; > + } > + end =3D (char __user *)PAGE_ALIGN((unsigned long)start + size); > + if (unlikely(end < start)) > + end =3D NULL; > + while (uaddr !=3D end) { > + if (unlikely(__put_user(0, uaddr) !=3D 0)) > + goto out; > + uaddr +=3D PAGE_SIZE; Won't we loop endlessly or corrupt some unwanted page when 'end' was set to NULL? > + } > + > +out: > + if (size > uaddr - start) > + return size - (uaddr - start); > + return 0; > +} > +EXPORT_SYMBOL(fault_in_writeable); > + > +/** > + * fault_in_readable - fault in userspace address range for reading > + * @uaddr: start of user address range > + * @size: size of user address range > + * > + * Returns the number of bytes not faulted in (like copy_to_user() and > + * copy_from_user()). > + */ > +size_t fault_in_readable(const char __user *uaddr, size_t size) > +{ > + const char __user *start =3D uaddr, *end; > + volatile char c; > + > + if (unlikely(size =3D=3D 0)) > + return 0; > + if (!PAGE_ALIGNED(uaddr)) { > + if (unlikely(__get_user(c, uaddr) !=3D 0)) > + return size; > + uaddr =3D (const char __user *)PAGE_ALIGN((unsigned long)= uaddr); > + } > + end =3D (const char __user *)PAGE_ALIGN((unsigned long)start + si= ze); > + if (unlikely(end < start)) > + end =3D NULL; > + while (uaddr !=3D end) { Same kind of issue here, when 'end' was set to NULL? Thanks. > + if (unlikely(__get_user(c, uaddr) !=3D 0)) > + goto out; > + uaddr +=3D PAGE_SIZE; > + } > + > +out: > + (void)c; > + if (size > uaddr - start) > + return size - (uaddr - start); > + return 0; > +} > +EXPORT_SYMBOL(fault_in_readable); > + > /** > * get_dump_page() - pin user page in memory while writing it to core du= mp > * @addr: user address > -- > 2.26.3 > --=20 Filipe David Manana, =E2=80=9CWhether you think you can, or you think you can't =E2=80=94 you're= right.=E2=80=9D