2022-02-25 16:02:45

by Herve Codina

Subject: [PATCH 1/1] dmaengine: dw-edma: Fix unaligned 64bit access

On some arch (ie aarch64 iMX8MM) unaligned PCIe accesses are
not allowed and lead to a kernel Oops.
[ 1911.668835] Unable to handle kernel paging request at virtual address ffff80001bc00a8c
[ 1911.668841] Mem abort info:
[ 1911.668844] ESR = 0x96000061
[ 1911.668847] EC = 0x25: DABT (current EL), IL = 32 bits
[ 1911.668850] SET = 0, FnV = 0
[ 1911.668852] EA = 0, S1PTW = 0
[ 1911.668853] Data abort info:
[ 1911.668855] ISV = 0, ISS = 0x00000061
[ 1911.668857] CM = 0, WnR = 1
[ 1911.668861] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000040ff4000
[ 1911.668864] [ffff80001bc00a8c] pgd=00000000bffff003, pud=00000000bfffe003, pmd=0068000018400705
[ 1911.668872] Internal error: Oops: 96000061 [#1] PREEMPT SMP
...

The llp register present in the channel group registers is not
aligned on 64bit.

Fix unaligned 64bit access using two 32bit accesses

Fixes: 04e0a39fc10f ("dmaengine: dw-edma: Add writeq() and readq() for 64 bits architectures")
Signed-off-by: Herve Codina <[email protected]>
---
drivers/dma/dw-edma/dw-edma-v0-core.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
index 329fc2e57b70..b5b8f8181e77 100644
--- a/drivers/dma/dw-edma/dw-edma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
@@ -415,8 +415,11 @@ void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
(DW_EDMA_V0_CCS | DW_EDMA_V0_LLE));
/* Linked list */
#ifdef CONFIG_64BIT
- SET_CH_64(dw, chan->dir, chan->id, llp.reg,
- chunk->ll_region.paddr);
+ /* llp is not aligned on 64bit -> keep 32bit accesses */
+ SET_CH_32(dw, chan->dir, chan->id, llp.lsb,
+ lower_32_bits(chunk->ll_region.paddr));
+ SET_CH_32(dw, chan->dir, chan->id, llp.msb,
+ upper_32_bits(chunk->ll_region.paddr));
#else /* CONFIG_64BIT */
SET_CH_32(dw, chan->dir, chan->id, llp.lsb,
lower_32_bits(chunk->ll_region.paddr));
--
2.35.1

2022-04-12 06:47:14

by Vinod Koul

Subject: Re: [PATCH 1/1] dmaengine: dw-edma: Fix unaligned 64bit access

On 25-02-22, 13:02, Herve Codina wrote:
> On some arch (ie aarch64 iMX8MM) unaligned PCIe accesses are
> not allowed and lead to a kernel Oops.
> [ 1911.668835] Unable to handle kernel paging request at virtual address ffff80001bc00a8c
> [ 1911.668841] Mem abort info:
> [ 1911.668844] ESR = 0x96000061
> [ 1911.668847] EC = 0x25: DABT (current EL), IL = 32 bits
> [ 1911.668850] SET = 0, FnV = 0
> [ 1911.668852] EA = 0, S1PTW = 0
> [ 1911.668853] Data abort info:
> [ 1911.668855] ISV = 0, ISS = 0x00000061
> [ 1911.668857] CM = 0, WnR = 1
> [ 1911.668861] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000040ff4000
> [ 1911.668864] [ffff80001bc00a8c] pgd=00000000bffff003, pud=00000000bfffe003, pmd=0068000018400705
> [ 1911.668872] Internal error: Oops: 96000061 [#1] PREEMPT SMP
> ...
>
> The llp register present in the channel group registers is not
> aligned on 64bit.
>
> Fix unaligned 64bit access using two 32bit accesses

Applied, thanks

--
~Vinod