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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 31 Jan 2019 11:06:44 -0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x0VB6hb544302338 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Thu, 31 Jan 2019 11:06:43 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 77784A4055; Thu, 31 Jan 2019 11:06:43 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 05551A4057; Thu, 31 Jan 2019 11:06:41 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.8.84]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Thu, 31 Jan 2019 11:06:40 +0000 (GMT) Date: Thu, 31 Jan 2019 13:06:39 +0200 From: Mike Rapoport To: Souptick Joarder Cc: Andrew Morton , Matthew Wilcox , Michal Hocko , "Kirill A. Shutemov" , vbabka@suse.cz, Rik van Riel , Stephen Rothwell , rppt@linux.vnet.ibm.com, Peter Zijlstra , Russell King - ARM Linux , robin.murphy@arm.com, iamjoonsoo.kim@lge.com, treding@nvidia.com, Kees Cook , Marek Szyprowski , stefanr@s5r6.in-berlin.de, hjc@rock-chips.com, Heiko Stuebner , airlied@linux.ie, oleksandr_andrushchenko@epam.com, joro@8bytes.org, pawel@osciak.com, Kyungmin Park , mchehab@kernel.org, Boris Ostrovsky , Juergen Gross , linux-kernel@vger.kernel.org, Linux-MM , linux-arm-kernel@lists.infradead.org, linux1394-devel@lists.sourceforge.net, dri-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, xen-devel@lists.xen.org, iommu@lists.linux-foundation.org, linux-media@vger.kernel.org Subject: Re: [PATCHv2 1/9] mm: Introduce new vm_insert_range and vm_insert_range_buggy API References: <20190131030812.GA2174@jordon-HP-15-Notebook-PC> <20190131083842.GE28876@rapoport-lnx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 19013111-0020-0000-0000-0000030F465E X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19013111-0021-0000-0000-000021604905 Message-Id: <20190131110638.GK28876@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-01-31_04:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1901310088 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 31, 2019 at 03:43:39PM +0530, Souptick Joarder wrote: > On Thu, Jan 31, 2019 at 2:09 PM Mike Rapoport wrote: > > > > On Thu, Jan 31, 2019 at 08:38:12AM +0530, Souptick Joarder wrote: > > > Previouly drivers have their own way of mapping range of > > > kernel pages/memory into user vma and this was done by > > > invoking vm_insert_page() within a loop. > > > > > > As this pattern is common across different drivers, it can > > > be generalized by creating new functions and use it across > > > the drivers. > > > > > > vm_insert_range() is the API which could be used to mapped > > > kernel memory/pages in drivers which has considered vm_pgoff > > > > > > vm_insert_range_buggy() is the API which could be used to map > > > range of kernel memory/pages in drivers which has not considered > > > vm_pgoff. vm_pgoff is passed default as 0 for those drivers. > > > > > > We _could_ then at a later "fix" these drivers which are using > > > vm_insert_range_buggy() to behave according to the normal vm_pgoff > > > offsetting simply by removing the _buggy suffix on the function > > > name and if that causes regressions, it gives us an easy way to revert. > > > > > > Signed-off-by: Souptick Joarder > > > Suggested-by: Russell King > > > Suggested-by: Matthew Wilcox > > > --- > > > include/linux/mm.h | 4 +++ > > > mm/memory.c | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > > > mm/nommu.c | 14 ++++++++++ > > > 3 files changed, 99 insertions(+) > > > > > > diff --git a/include/linux/mm.h b/include/linux/mm.h > > > index 80bb640..25752b0 100644 > > > --- a/include/linux/mm.h > > > +++ b/include/linux/mm.h > > > @@ -2565,6 +2565,10 @@ unsigned long change_prot_numa(struct vm_area_struct *vma, > > > int remap_pfn_range(struct vm_area_struct *, unsigned long addr, > > > unsigned long pfn, unsigned long size, pgprot_t); > > > int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *); > > > +int vm_insert_range(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num); > > > +int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num); > > > vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr, > > > unsigned long pfn); > > > vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, > > > diff --git a/mm/memory.c b/mm/memory.c > > > index e11ca9d..0a4bf57 100644 > > > --- a/mm/memory.c > > > +++ b/mm/memory.c > > > @@ -1520,6 +1520,87 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, > > > } > > > EXPORT_SYMBOL(vm_insert_page); > > > > > > +/** > > > + * __vm_insert_range - insert range of kernel pages into user vma > > > + * @vma: user vma to map to > > > + * @pages: pointer to array of source kernel pages > > > + * @num: number of pages in page array > > > + * @offset: user's requested vm_pgoff > > > + * > > > + * This allows drivers to insert range of kernel pages they've allocated > > > + * into a user vma. > > > + * > > > + * If we fail to insert any page into the vma, the function will return > > > + * immediately leaving any previously inserted pages present. Callers > > > + * from the mmap handler may immediately return the error as their caller > > > + * will destroy the vma, removing any successfully inserted pages. Other > > > + * callers should make their own arrangements for calling unmap_region(). > > > + * > > > + * Context: Process context. > > > + * Return: 0 on success and error code otherwise. > > > + */ > > > +static int __vm_insert_range(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num, unsigned long offset) > > > +{ > > > + unsigned long count = vma_pages(vma); > > > + unsigned long uaddr = vma->vm_start; > > > + int ret, i; > > > + > > > + /* Fail if the user requested offset is beyond the end of the object */ > > > + if (offset > num) > > > + return -ENXIO; > > > + > > > + /* Fail if the user requested size exceeds available object size */ > > > + if (count > num - offset) > > > + return -ENXIO; > > > + > > > + for (i = 0; i < count; i++) { > > > + ret = vm_insert_page(vma, uaddr, pages[offset + i]); > > > + if (ret < 0) > > > + return ret; > > > + uaddr += PAGE_SIZE; > > > + } > > > + > > > + return 0; > > > +} > > > + > > > +/** > > > + * vm_insert_range - insert range of kernel pages starts with non zero offset > > > + * @vma: user vma to map to > > > + * @pages: pointer to array of source kernel pages > > > + * @num: number of pages in page array > > > + * > > > + * Maps an object consisting of `num' `pages', catering for the user's > > > + * requested vm_pgoff > > > + * > > > > The elaborate description you've added to __vm_insert_range() is better put > > here, as this is the "public" function. > > Ok, will add it in v3. Which means __vm_insert_range() still needs a short > description ? It won't hurt ;-) > > > > > + * Context: Process context. Called by mmap handlers. > > > + * Return: 0 on success and error code otherwise. > > > + */ > > > +int vm_insert_range(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num) > > > +{ > > > + return __vm_insert_range(vma, pages, num, vma->vm_pgoff); > > > +} > > > +EXPORT_SYMBOL(vm_insert_range); > > > + > > > +/** > > > + * vm_insert_range_buggy - insert range of kernel pages starts with zero offset > > > + * @vma: user vma to map to > > > + * @pages: pointer to array of source kernel pages > > > + * @num: number of pages in page array > > > + * > > > + * Maps a set of pages, always starting at page[0] > > > > Here I'd add something like: > > > > Similar to vm_insert_range(), except that it explicitly sets @vm_pgoff to > > 0. This function is intended for the drivers that did not consider > > @vm_pgoff. > > Ok. > > > > > > vm_insert_range_buggy() is the API which could be used to map > > > range of kernel memory/pages in drivers which has not considered > > > vm_pgoff. vm_pgoff is passed default as 0 for those drivers. > > > > > + * > > > + * Context: Process context. Called by mmap handlers. > > > + * Return: 0 on success and error code otherwise. > > > + */ > > > +int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num) > > > +{ > > > + return __vm_insert_range(vma, pages, num, 0); > > > +} > > > +EXPORT_SYMBOL(vm_insert_range_buggy); > > > + > > > static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr, > > > pfn_t pfn, pgprot_t prot, bool mkwrite) > > > { > > > diff --git a/mm/nommu.c b/mm/nommu.c > > > index 749276b..21d101e 100644 > > > --- a/mm/nommu.c > > > +++ b/mm/nommu.c > > > @@ -473,6 +473,20 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, > > > } > > > EXPORT_SYMBOL(vm_insert_page); > > > > > > +int vm_insert_range(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num) > > > +{ > > > + return -EINVAL; > > > +} > > > +EXPORT_SYMBOL(vm_insert_range); > > > + > > > +int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages, > > > + unsigned long num) > > > +{ > > > + return -EINVAL; > > > +} > > > +EXPORT_SYMBOL(vm_insert_range_buggy); > > > + > > > /* > > > * sys_brk() for the most part doesn't need the global kernel > > > * lock, except when an application is doing something nasty > > > -- > > > 1.9.1 > > > > > > > -- > > Sincerely yours, > > Mike. > > > -- Sincerely yours, Mike.