On Sun, Apr 17, 2022 at 3:32 AM Corentin Labbe <clabbe.montjoie@xxxxxxxxx> wrote: > > Le Sat, Apr 16, 2022 at 12:47:29PM -0500, Samuel Holland a écrit : > > On 4/16/22 2:35 AM, Corentin Labbe wrote: > > > Le Fri, Apr 15, 2022 at 09:19:23PM -0500, Samuel Holland a écrit : > > >> On 4/15/22 6:26 AM, Corentin Labbe wrote: > > >>> 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); > > >> > > >> This function (through dma_direct_map_page()) ends up calling > > >> arch_sync_dma_for_device(..., ..., DMA_FROM_DEVICE), which invalidates the CPU's > > >> cache. This is the same thing other architectures do (at least arm, arm64, > > >> openrisc, and powerpc). So this appears to be working as intended. > > > > > > This behavour is not present at least on ARM and ARM64. > > > The sample code I provided does not corrupt the buffer on them. > > > > That can be explained by the 0xFE bytes having been flushed to DRAM already in > > your ARM/ARM64 tests, whereas in your riscv64 case, the 0xFE bytes were still in > > a dirty cache line. The cache topology and implementation is totally different > > across the SoCs, so this is not too surprising. > > > > Semantically, dma_map_single(..., DMA_FROM_DEVICE) means you are doing a > > unidirectional DMA transfer from the device into that buffer. So the contents of > > the buffer are "undefined" until the DMA transfer completes. If you are also > > writing data into the buffer from the CPU side, then you need DMA_BIDIRECTIONAL. > > > > Regards, > > Samuel > > +CC crypto mailing list + maintainer > > My problem is that crypto selftest, for each buffer where I need to do a cipher operation, > concat a poison buffer to check that device does write beyond buffer. > > But the dma_map_sg(FROM_DEVICE) corrupts this poison buffer and crypto selftests fails thinking my device did a buffer overrun. > > So you mean that on SoC D1, this crypto API check strategy is impossible ? I think you could try to replace all CLEAN & INVAL ops with FLUSH ops for the testing. (All cache block-aligned data from the device for the CPU should be invalided.) +void arch_sync_dma_for_device(phys_addr_t paddr, size_t size, enum dma_data_direction dir) +{ + switch (dir) { + case DMA_TO_DEVICE: + ALT_CMO_OP(CLEAN, (unsigned long)phys_to_virt(paddr), size); + break; + case DMA_FROM_DEVICE: + ALT_CMO_OP(INVAL, (unsigned long)phys_to_virt(paddr), size); + break; + case DMA_BIDIRECTIONAL: + ALT_CMO_OP(FLUSH, (unsigned long)phys_to_virt(paddr), size); + break; + default: + break; + } +} + +void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size, enum dma_data_direction dir) +{ + switch (dir) { + case DMA_TO_DEVICE: + break; + case DMA_FROM_DEVICE: + case DMA_BIDIRECTIONAL: + ALT_CMO_OP(INVAL, (unsigned long)phys_to_virt(paddr), size); + break; + default: + break; + } +} -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/
