Author: andrew Date: Thu Sep 24 07:13:13 2020 New Revision: 366105 URL: https://svnweb.freebsd.org/changeset/base/366105
Log: Ensure we always align and size arm64 busdma allocations to a cacheline This will ensure nothing modifies the cacheline while DMA is in progress so we won't need to bounce the data. Reviewed by: mmel Sponsored by: Innovate UK Differential Revision: https://reviews.freebsd.org/D26495 Modified: head/sys/arm64/arm64/busdma_bounce.c Modified: head/sys/arm64/arm64/busdma_bounce.c ============================================================================== --- head/sys/arm64/arm64/busdma_bounce.c Thu Sep 24 07:10:34 2020 (r366104) +++ head/sys/arm64/arm64/busdma_bounce.c Thu Sep 24 07:13:13 2020 (r366105) @@ -72,6 +72,8 @@ struct bounce_zone; struct bus_dma_tag { struct bus_dma_tag_common common; + size_t alloc_size; + size_t alloc_alignment; int map_count; int bounce_flags; bus_dma_segment_t *segments; @@ -208,8 +210,22 @@ bounce_bus_dma_tag_create(bus_dma_tag_t parent, bus_si newtag->map_count = 0; newtag->segments = NULL; - if ((flags & BUS_DMA_COHERENT) != 0) + if ((flags & BUS_DMA_COHERENT) != 0) { newtag->bounce_flags |= BF_COHERENT; + newtag->alloc_alignment = newtag->common.alignment; + newtag->alloc_size = newtag->common.maxsize; + } else { + /* + * Ensure the buffer is aligned to a cacheline when allocating + * a non-coherent buffer. This is so we don't have any data + * that another CPU may be accessing around DMA buffer + * causing the cache to become dirty. + */ + newtag->alloc_alignment = MAX(newtag->common.alignment, + dcache_line_size); + newtag->alloc_size = roundup2(newtag->common.maxsize, + dcache_line_size); + } if (parent != NULL) { if ((newtag->common.filter != NULL || @@ -520,23 +536,23 @@ bounce_bus_dmamem_alloc(bus_dma_tag_t dmat, void** vad * * In the meantime warn the user if malloc gets it wrong. */ - if ((dmat->common.maxsize <= PAGE_SIZE) && - (dmat->common.alignment <= dmat->common.maxsize) && + if ((dmat->alloc_size <= PAGE_SIZE) && + (dmat->alloc_alignment <= dmat->alloc_size) && dmat->common.lowaddr >= ptoa((vm_paddr_t)Maxmem) && attr == VM_MEMATTR_DEFAULT) { - *vaddr = malloc(dmat->common.maxsize, M_DEVBUF, mflags); + *vaddr = malloc(dmat->alloc_size, M_DEVBUF, mflags); } else if (dmat->common.nsegments >= - howmany(dmat->common.maxsize, MIN(dmat->common.maxsegsz, PAGE_SIZE)) && - dmat->common.alignment <= PAGE_SIZE && + howmany(dmat->alloc_size, MIN(dmat->common.maxsegsz, PAGE_SIZE)) && + dmat->alloc_alignment <= PAGE_SIZE && (dmat->common.boundary % PAGE_SIZE) == 0) { /* Page-based multi-segment allocations allowed */ - *vaddr = (void *)kmem_alloc_attr(dmat->common.maxsize, mflags, + *vaddr = (void *)kmem_alloc_attr(dmat->alloc_size, mflags, 0ul, dmat->common.lowaddr, attr); dmat->bounce_flags |= BF_KMEM_ALLOC; } else { - *vaddr = (void *)kmem_alloc_contig(dmat->common.maxsize, mflags, - 0ul, dmat->common.lowaddr, dmat->common.alignment != 0 ? - dmat->common.alignment : 1ul, dmat->common.boundary, attr); + *vaddr = (void *)kmem_alloc_contig(dmat->alloc_size, mflags, + 0ul, dmat->common.lowaddr, dmat->alloc_alignment != 0 ? + dmat->alloc_alignment : 1ul, dmat->common.boundary, attr); dmat->bounce_flags |= BF_KMEM_ALLOC; } if (*vaddr == NULL) { @@ -544,7 +560,7 @@ bounce_bus_dmamem_alloc(bus_dma_tag_t dmat, void** vad __func__, dmat, dmat->common.flags, ENOMEM); free(*mapp, M_DEVBUF); return (ENOMEM); - } else if (vtophys(*vaddr) & (dmat->common.alignment - 1)) { + } else if (vtophys(*vaddr) & (dmat->alloc_alignment - 1)) { printf("bus_dmamem_alloc failed to align memory properly.\n"); } dmat->map_count++; @@ -571,7 +587,7 @@ bounce_bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr if ((dmat->bounce_flags & BF_KMEM_ALLOC) == 0) free(vaddr, M_DEVBUF); else - kmem_free((vm_offset_t)vaddr, dmat->common.maxsize); + kmem_free((vm_offset_t)vaddr, dmat->alloc_size); free(map, M_DEVBUF); dmat->map_count--; CTR3(KTR_BUSDMA, "%s: tag %p flags 0x%x", __func__, dmat, _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
