Strengthen the sanity checking of busdma tag parameters.
It turns out an alignment of zero can lead to an endless loop in the vm reservations code, so specifically disallow that. The manpage says hardware which can do dma at any address should use a value of one, which hints at the forbiddeness of zero without exactly saying it. Several other conditions which could lead to insanity in working with the tag are also checked now. Every existing call to bus_dma_tag_create() (about 680 of them) was eyeballed for violations of these things, and two alignment=0 glitches were fixed. It's possible something was missed, but overall this shouldn't lead to any arm users suddenly experiencing failures.
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=274191
@ -64,6 +64,8 @@ __FBSDID("$FreeBSD$");
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#include <machine/cpufunc.h>
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#include <machine/md_var.h>
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#define IS_POWER_OF_2(val) (((val) & ((val) - 1)) == 0)
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#define MAX_BPAGES 64
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#define MAX_DMA_SEGMENTS 4096
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#define BUS_DMA_EXCL_BOUNCE BUS_DMA_BUS2
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@ -466,17 +468,18 @@ bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
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parent = arm_root_dma_tag;
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#endif
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/* Basic sanity checking */
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if (boundary != 0 && boundary < maxsegsz)
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maxsegsz = boundary;
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/* Basic sanity checking. */
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KASSERT(boundary == 0 || IS_POWER_OF_2(boundary),
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("dma tag boundary %lu, must be a power of 2", boundary));
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KASSERT(boundary == 0 || boundary >= maxsegsz,
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("dma tag boundary %lu is < maxsegsz %lu\n", boundary, maxsegsz));
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KASSERT(alignment != 0 && IS_POWER_OF_2(alignment),
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("dma tag alignment %lu, must be non-zero power of 2", alignment));
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KASSERT(maxsegsz != 0, ("dma tag maxsegsz must not be zero"));
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/* Return a NULL tag on failure */
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*dmat = NULL;
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if (maxsegsz == 0) {
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return (EINVAL);
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}
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newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_DEVBUF,
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M_ZERO | M_NOWAIT);
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if (newtag == NULL) {
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