Fixed the commit message. Please find the new patch below:
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 protected]>
Acked-by: Laurent Pinchart <[email protected]>
---
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 protected]> 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 protected]>
>
>> On Sat, Apr 19, 2014 at 4:49 PM, Ritesh Harjani
>>
>> <[email protected]> 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 protected]>
>> > 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 protected]>
>> > ---
>> >
>> > 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
>
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