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MFamd64 r204214: Enforce stronger alignment semantics (require that the

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end of segments be aligned, not just the start of segments) in order to
allow Xen's blkfront driver to operate correctly.

PR:		kern/152818
MFC after:	3 days
This commit is contained in:
cperciva 2010-12-05 03:20:55 +00:00
parent 40fdbfec53
commit 0476c48e6f
1 changed files with 18 additions and 12 deletions
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30
sys/i386/i386/busdma_machdep.c
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@ -246,8 +246,7 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
newtag->alignment = alignment;
newtag->boundary = boundary;
newtag->lowaddr = trunc_page((vm_paddr_t)lowaddr) + (PAGE_SIZE - 1);
newtag->highaddr = trunc_page((vm_paddr_t)highaddr) +
(PAGE_SIZE - 1);
newtag->highaddr = trunc_page((vm_paddr_t)highaddr) + (PAGE_SIZE - 1);
newtag->filter = filter;
newtag->filterarg = filterarg;
newtag->maxsize = maxsize;
@ -594,15 +593,19 @@ _bus_dmamap_count_pages(bus_dma_tag_t dmat, bus_dmamap_t map, pmap_t pmap,
vendaddr = (vm_offset_t)buf + buflen;
while (vaddr < vendaddr) {
bus_size_t sg_len;
sg_len = PAGE_SIZE - ((vm_offset_t)vaddr & PAGE_MASK);
if (pmap)
paddr = pmap_extract(pmap, vaddr);
else
paddr = pmap_kextract(vaddr);
if (((dmat->flags & BUS_DMA_COULD_BOUNCE) != 0) &&
run_filter(dmat, paddr) != 0) {
sg_len = roundup2(sg_len, dmat->alignment);
map->pagesneeded++;
}
vaddr += (PAGE_SIZE - ((vm_offset_t)vaddr & PAGE_MASK));
vaddr += sg_len;
}
CTR1(KTR_BUSDMA, "pagesneeded= %d\n", map->pagesneeded);
}
@ -669,6 +672,8 @@ _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
bmask = ~(dmat->boundary - 1);
for (seg = *segp; buflen > 0 ; ) {
bus_size_t max_sgsize;
/*
* Get the physical address for this segment.
*/
@ -680,11 +685,16 @@ _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
/*
* Compute the segment size, and adjust counts.
*/
sgsize = PAGE_SIZE - ((u_long)curaddr & PAGE_MASK);
if (sgsize > dmat->maxsegsz)
sgsize = dmat->maxsegsz;
if (buflen < sgsize)
sgsize = buflen;
max_sgsize = MIN(buflen, dmat->maxsegsz);
sgsize = PAGE_SIZE - ((vm_offset_t)curaddr & PAGE_MASK);
if (((dmat->flags & BUS_DMA_COULD_BOUNCE) != 0) &&
map->pagesneeded != 0 && run_filter(dmat, curaddr)) {
sgsize = roundup2(sgsize, dmat->alignment);
sgsize = MIN(sgsize, max_sgsize);
curaddr = add_bounce_page(dmat, map, vaddr, sgsize);
} else {
sgsize = MIN(sgsize, max_sgsize);
}
/*
* Make sure we don't cross any boundaries.
@ -695,10 +705,6 @@ _bus_dmamap_load_buffer(bus_dma_tag_t dmat,
sgsize = (baddr - curaddr);
}
if (((dmat->flags & BUS_DMA_COULD_BOUNCE) != 0) &&
map->pagesneeded != 0 && run_filter(dmat, curaddr))
curaddr = add_bounce_page(dmat, map, vaddr, sgsize);
/*
* Insert chunk into a segment, coalescing with
* previous segment if possible.