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

From: [email-masked] (Laurent Pinchart)
Date: Mon, 21 Apr 2014 11:53:12 +0200

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" ?

> 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 <[email-masked]>
> Acked-by: Laurent Pinchart <[email-masked]>
> ---
>  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
> 
> <[email-masked]> 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 <[email-masked]>
> > 
> >> On Sat, Apr 19, 2014 at 4:49 PM, Ritesh Harjani
> >> 
> >> <[email-masked]> 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 <[email-masked]>
> >> > 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 <[email-masked]>
> >> > ---
> >> > 
> >> >  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