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Properly handle alignment requests bigger that page size.

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- for now, alignments bigger that page size is allowed only for buffers
   allocated by bus_dmamem_alloc(), cover this fact by KASSERT.
 - never bounce buffers allocated by bus_dmamem_alloc(), these always comply
   with the required rules (alignment, boundary, address range).

MFC after:	1 week
Reviewed by:	jah
PR:		235542
This commit is contained in:
Michal Meloun 2019-02-10 14:25:29 +00:00
parent d9707e43df
commit 74a2bcfa80
1 changed files with 14 additions and 3 deletions
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17
sys/arm/arm/busdma_machdep-v6.c
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@ -339,16 +339,27 @@ cacheline_bounce(bus_dmamap_t map, bus_addr_t addr, bus_size_t size)
*
* Note that the addr argument might be either virtual or physical. It doesn't
* matter because we only look at the low-order bits, which are the same in both
* address spaces.
* address spaces and maximum alignment of generic buffer is limited up to page
* size.
* Bouncing of buffers allocated by bus_dmamem_alloc()is not necessary, these
* always comply with the required rules (alignment, boundary, and address
* range).
*/
static __inline int
might_bounce(bus_dma_tag_t dmat, bus_dmamap_t map, bus_addr_t addr,
bus_size_t size)
{
return ((dmat->flags & BUS_DMA_EXCL_BOUNCE) ||
KASSERT(dmat->flags & DMAMAP_DMAMEM_ALLOC ||
dmat->alignment <= PAGE_SIZE,
("%s: unsupported alignment (0x%08lx) for buffer not "
"allocated by bus_dmamem_alloc()",
__func__, dmat->alignment));
return (!(dmat->flags & DMAMAP_DMAMEM_ALLOC) &&
((dmat->flags & BUS_DMA_EXCL_BOUNCE) ||
alignment_bounce(dmat, addr) ||
cacheline_bounce(map, addr, size));
cacheline_bounce(map, addr, size)));
}
/*