From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Szyprowski Subject: Re: [PATCH] arm: dma-mapping: Fix mapping size value Date: Wed, 23 Apr 2014 10:53:24 +0200 Message-ID: <53577F84.1080101@samsung.com> References: <1398062847-5770-1-git-send-email-ritesh.harjani@gmail.com> <1398062847-5770-2-git-send-email-ritesh.harjani@gmail.com> <20140422085307.GB5747@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <20140422085307.GB5747-5wv7dgnIgG8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Will Deacon , Ritesh Harjani Cc: "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "mp.vikram-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , Catalin Marinas , "menon.vinayak-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org" , "rmk-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org" List-Id: iommu@lists.linux-foundation.org Hello, On 2014-04-22 10:53, Will Deacon wrote: > On Mon, Apr 21, 2014 at 07:47:27AM +0100, Ritesh Harjani wrote: > > 68efd7d2fb("arm: dma-mapping: remove order parameter from > > arm_iommu_create_mapping()") is causing kernel panic > > because it wrongly sets the value of mapping->size: > > > > Unable to handle kernel NULL pointer dereference at virtual > > address 000000a0 > > pgd = e7a84000 > > [000000a0] *pgd=00000000 > > ... > > PC is at bitmap_clear+0x48/0xd0 > > LR is at __iommu_remove_mapping+0x130/0x164 > > > > Fix it by correcting mapping->size value. > > > > Signed-off-by: Ritesh Harjani > > Acked-by: Laurent Pinchart > > --- > > arch/arm/mm/dma-mapping.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > > index f62aa06..6b00be1 100644 > > --- a/arch/arm/mm/dma-mapping.c > > +++ b/arch/arm/mm/dma-mapping.c > > @@ -1963,8 +1963,8 @@ arm_iommu_create_mapping(struct bus_type *bus, dma_addr_t base, size_t size) > > mapping->nr_bitmaps = 1; > > mapping->extensions = extensions; > > mapping->base = base; > > - mapping->size = bitmap_size << PAGE_SHIFT; > > mapping->bits = BITS_PER_BYTE * bitmap_size; > > + mapping->size = mapping->bits << PAGE_SHIFT; > > Ok, but given that mapping->size is derived from mapping->bits, do we really > need both of these fields in struct dma_iommu_mapping? You are right. I didn't notice this while I was refactoring the code. Ritesh, could you update your patch and simply replace all references of mapping->size with (mapping->bits << PAGE_SHIFT), probably with some temporary variable to make the code easier to understand? I've didn't apply your patch yet. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland