Re: [PATCH] arm: dma-mapping: Fix mapping size value

[Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>]

On Monday 21 April 2014 11:53:12 Laurent Pinchart wrote:
> Hi Ritesh,
> 
> On Monday 21 April 2014 09:31:38 Ritesh Harjani wrote:
> > Fixed the commit message. Please find the new patch below:
> Thank you. Your mail has wrapped lines and converted tabs to whitespaces.
> Could you please fix that and resubmit the patch on a mail of its own (use
> git send-email to avoid white space issues), with the subject set to
> "[PATCH v2] arm: dma-mapping: Fix mapping size value" ?

Please ignore this, I had missed that you have already resent the patch.
> 
> > 68efd7d2fb("arm: dma-mapping: remove order parameter from
> > arm_iommu_create_mapping()") is causing kernel panic
> > because it wrongly sets the mapping->size value.
> > 
> > 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 the mapping->size value.
> > 
> > Signed-off-by: Ritesh Harjani <ritesh.harjani-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > Acked-by: Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
> > ---
> > 
> >  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;
> > 
> >         spin_lock_init(&mapping->lock);
> > 
> > --
> > 1.8.1.3
> > 
> > On Mon, Apr 21, 2014 at 4:06 AM, Laurent Pinchart
> > 
> > <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org> wrote:
> > > Hi Ritesh,
> > > 
> > > On Saturday 19 April 2014 16:55:30 Ritesh Harjani wrote:
> > >> In explaining the issue below, made a mistake of taking PAGE_SIZE
> > >> instead of PAGE_SHIFT (mistake mentioned inline).
> > >> Although numerical values and patch is correct.
> > > 
> > > I was about to send the same patch, so, provided you fix the commit
> > > message,
> > > 
> > > Acked-by: Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>
> > > 
> > >> On Sat, Apr 19, 2014 at 4:49 PM, Ritesh Harjani
> > >> 
> > >> <ritesh.harjani-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > >> > I am finding an oops after following commit. I am on 3.10.30 kernel
> > >> > but
> > >> > applied all the latest patches from arch/arm/mm/dma-mapping.c
> > >> > 
> > >> > I added some debug logs to see what is the error, on which I found
> > >> > that
> > >> > we
> > >> > are incorrectly setting mapping->size value.
> > >> > Please take a look at this and correct me if I am wrong here.
> > >> > 
> > >> > FAULTY COMMIT:
> > >> > commit 68efd7d2fb32c2606f1da318b6a851
> > >> > d933813f27
> > >> > Author: Marek Szyprowski <m.szyprowski-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
> > >> > Date:   Tue Feb 25 13:01:09 2014 +0100
> > >> > 
> > >> >     arm: dma-mapping: remove order parameter from
> > >> >     arm_iommu_create_mapping()
> > >> > 
> > >> > OOPS LOGS:
> > >> > [26.898145] __alloc_iova#LINE: 1097 start = 0x3500
> > >> > [26.898159] __alloc_iova#LINE:1136 iova = 0x53500000
> > >> > [26.898170] __alloc_iova#LINE:1138 mapping->base= 0x50000000
> > >> > [26.898181] __alloc_iova#LINE:1140 mapping->size = 0x1000000, i = 0
> > >> > [26.924442] __free_iova, bitmap_index = 3
> > >> > 
> > >> > [Ritesh]: bitmap_index should be 0 for address 0x53500000. see in
> > >> > alloc_iova above.
> > >> > 
> > >> > [26.924454] __free_iova,addr = 0x53500000
> > >> > [26.924463] __free_iova,mapping->base = 0x50000000
> > >> > [26.924472] __free_iova,mapping->size = 0x1000000
> > >> > [26.924482] __free_iova,bitmap_base = 0x53000000
> > >> > [26.924490] __free_iova, start = 0x500
> > >> > 
> > >> > [Ritesh]: start should be 0x3500 for address 0x53500000. see in
> > >> > alloc_iova
> > >> > above.
> > >> > 
> > >> > [26.924533] Unable to handle kernel NULL pointer dereference at
> > >> > virtual
> > >> > address 000000a0
> > >> > [26.924543] pgd = e7a84000
> > >> > [26.924558] [000000a0] *pgd=00000000
> > >> > [26.924572] Internal error: Oops: 5 [#1] PREEMPT SMP ARM
> > >> > [26.924598] Modules linked in:
> > >> > [26.924613] CPU: 1 PID: 2263 Comm: BufferLiberator Not tainted
> > >> > 3.10.30+
> > >> > #144
> > >> > [26.924624] task: e7370a40 ti: e6e06000 task.ti: e6e06000
> > >> > [26.924644] PC is at bitmap_clear+0x48/0xd0
> > >> > [26.924659] LR is at __iommu_remove_mapping+0x130/0x164
> > >> > [26.924673] pc : [<c02d0814>]    lr : [<c001bd30>]    psr: 20000093
> > >> > [26.924673] sp : e6e07e20  ip : ffffffff  fp : e6e07e3c
> > >> > [26.924682] r10: 00000500  r9 : c1333ea8  r8 : 80000013
> > >> > [26.924692] r7 : ffffffff  r6 : 00000321  r5 : 000000a0  r4 :
> > >> > 00000028
> > >> > [26.924707] r3 : 00000000  r2 : 00000341  r1 : 00000500  r0 :
> > >> > 00000000
> > >> > [26.924730] Flags: nzCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM
> > >> > Segment
> > >> > user
> > >> > [26.924742] Control: 10c5387d  Table: 77a8406a  DAC: 00000015
> > >> > 
> > >> > 
> > >> > See below on how this is wrong:
> > >> > 
> > >> > here iova_base = 0x50000000
> > >> > iova_size = 0x20000000
> > >> > => bits needed to map = 131072.
> > >> > 
> > >> >         => bitmap_size = 0x4000
> > >> >         since bitmap_size > PAGE_SIZE
> > >> >         => bitmap_size = PAGE_SIZE,  extensions = 4;
> > >> > 
> > >> > Now, mapping->size is currently set as bitmap_size << PAGE_SHIFT.
> > >> > 
> > >> >         =>mapping->size = 0x1000000.
> > >> > 
> > >> > mapping->size is the IOVA size, which one bitmap can address.
> > >> > 
> > >> > Now mapping->size * extensions should be size (0x20000000).
> > >> > which is not true, => our bitmap_size is set wrong.
> > >> > 
> > >> > it should be (mapping->bits << PAGE_SIZE) or say
> > >> 
> > >> It should be PAGE_SHIFT here.
> > >> 
> > >> > (BITS_PER_BYTE * bitmap_size << PAGE_SIZE)
> > >> 
> > >> It should be PAGE_SHIFT here.
> > >> 
> > >> >         => (8 * 0x1000) << 12) = 0x8000000
> > >> > 
> > >> > With this IOVA_SIZE = extensions * mapping->size = 0x20000000
> > >> > 
> > >> > 
> > >> > 
> > >> > PATCH:
> > >> > 
> > >> > Currently mapping->size is wrongly set resulting
> > >> > in OOPS (atleast we see OOPS with extension 4).
> > >> > 
> > >> > Fix this.
> > >> > 
> > >> > Signed-off-by: Ritesh Harjani <ritesh.harjani-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> > >> > ---
> > >> > 
> > >> >  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..d1701a2 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;
> > >> > 
> > >> >         spin_lock_init(&mapping->lock);

-- 
Regards,

Laurent Pinchart