Re: [PATCH 0/2] riscv: implement Zicbom-based CMO instructions + the t-head variant

[Corentin Labbe]

Le Mon, Mar 07, 2022 at 11:46:18PM +0100, Heiko Stuebner a écrit :
> This series is based on the alternatives changes done in my svpbmt series
> and thus also depends on Atish's isa-extension parsing series.
> 
> It implements using the cache-management instructions from the  Zicbom-
> extension to handle cache flush, etc actions on platforms needing them.
> 
> SoCs using cpu cores from T-Head like the Allwinne D1 implement a
> different set of cache instructions. But while they are different,
> instructions they provide the same functionality, so a variant can
> easly hook into the existing alternatives mechanism on those.
> 
> 

Hello

I am testing https://github.com/smaeul/linux.git branch:origin/riscv/d1-wip which contain this serie.

I am hitting a buffer corruption problem with DMA.
The sun8i-ce crypto driver fail self tests due to "device overran destination buffer".
In fact the buffer is not overran by device but by dma_map_single() operation.

The following small code show the problem:

dma_addr_t dma;
u8 *buf;
#define BSIZE 2048
#define DMASIZE 16

buf = kmalloc(BSIZE, GFP_KERNEL | GFP_DMA);
for (i = 0; i < BSIZE; i++)
    buf[i] = 0xFE;
print_hex_dump(KERN_INFO, "DMATEST1:", DUMP_PREFIX_NONE, 16, 4, buf, 256, false);
dma = dma_map_single(ce->dev, buf, DMASIZE, DMA_FROM_DEVICE);
dma_unmap_single(ce->dev, dma, DMASIZE, DMA_FROM_DEVICE);
print_hex_dump(KERN_INFO, "DMATEST3:", DUMP_PREFIX_NONE, 16, 4, buf, 256, false);

Will lead to:
[    2.960040] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    2.965354] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    2.970709] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    2.976069] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    2.981440] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    2.986814] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    2.992188] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    2.997560] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    3.002934] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    3.008307] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    3.013680] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    3.019054] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    3.024427] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    3.029802] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    3.035175] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    3.040546] DMATEST1:fefefefe fefefefe fefefefe fefefefe
[    3.401647] DMATEST3:a9c3a9c3 a9c3a9c3 a9c3a9c3 a9c3a9c3
[    3.406982] DMATEST3:a9c3a9c3 a9c3a9c3 a9c3a9c3 a9c3a9c3
[    3.412350] DMATEST3:a9c3a9c3 a9c3a9c3 a9c3a9c3 a9c3a9c3
[    3.417720] DMATEST3:a9c3a9c3 a9c3a9c3 a9c3a9c3 a9c3a9c3
[    3.423094] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.428468] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.433841] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.439213] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.444588] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.449962] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.455334] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.460707] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.466081] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.471454] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.476828] DMATEST3:fefefefe fefefefe fefefefe fefefefe
[    3.482200] DMATEST3:fefefefe fefefefe fefefefe fefefefe

Even with no DMA action, the buffer is corrupted.

Regards