Messages in this thread | | | Subject | Re: DMA mapping fill dma_address to 0 | From | Robin Murphy <> | Date | Wed, 28 Apr 2021 11:06:10 +0100 |
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On 2021-04-28 09:42, Corentin Labbe wrote: > Hello > > I work on the crypto offloader driver of cortina/gemini SL3516 SoC. > I test it by filling a LUKS2 partition. > I got a reproductible problem when handling skcipher requests. > I use dma_map_sg() and when iterating other the result, sg_dma_address(sg) return 0. > But sg_dma_len(sg) is still correct (4096 in my case). > > Below is a simplified view of my code: > nr_sgs = dma_map_sg(ce->dev, areq->src, sg_nents(areq->src), DMA_TO_DEVICE); > (nr_sgs = 1 in my case) > sg = areq->src; > if (!sg_dma_address(sg)) > FAIL
What is this check supposed to be for in the first place? 0 is a valid DMA address, because it's also a valid physical address, and I recall RAM at PA 0 on Hikey 960 flushing out some bugs in the past when we tried to use 0 for DMA_MAPPING_ERROR. All the Gemini DTs appear to show RAM starting at PA 0 too, so I'd have to guess that it's simply the case that your DMA buffer happened to end up using that particular page.
Robin.
> I have digged to find what do dma_map_sg() and I have added some debug. > sg_page(sg) return c7efb000 for example so sg_page() works. > But it seems the problem is that page_to_phys(sg_page(sg)) return 0. > > This problem does not appear immediatly, luksOpen and subsequent fsck always work. > But it appears fast after, when mouting or rsync files in it. > > I have added CONFIG_DEBUG_SG, CONFIG_DMA_API_DEBUG, CONFIG_DMA_API_DEBUG_SG but they didnt bringed any more hints. > Only "DMA-API: cacheline tracking ENOMEM, dma-debug disabled" appears but always with some "time" between my problem and its display. > So I am not sure it is related. > > Regards > _______________________________________________ > iommu mailing list > iommu@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/iommu >
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