svn commit: r366106 - head/sys/arm64/arm64
Andrew Turner
andrew at FreeBSD.org
Thu Sep 24 07:17:06 UTC 2020
Author: andrew
Date: Thu Sep 24 07:17:05 2020
New Revision: 366106
URL: https://svnweb.freebsd.org/changeset/base/366106
Log:
Bounce in more cases in the arm64 busdma
We need to use a bounce buffer when the memory we are operating on is not
aligned to a cacheline, and not aligned to the maps alignment.
The former is to stop other threads from dirtying the cacheline while we
are performing DMA operations with it. The latter is to check memory
passed in by a driver is correctly aligned for the device.
Reviewed by: mmel
Sponsored by: Innovate UK
Differential Revision: https://reviews.freebsd.org/D26496
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 07:13:13 2020 (r366105)
+++ head/sys/arm64/arm64/busdma_bounce.c Thu Sep 24 07:17:05 2020 (r366106)
@@ -139,6 +139,7 @@ struct bus_dmamap {
u_int flags;
#define DMAMAP_COHERENT (1 << 0)
#define DMAMAP_FROM_DMAMEM (1 << 1)
+#define DMAMAP_MBUF (1 << 2)
int sync_count;
struct sync_list slist[];
};
@@ -155,8 +156,8 @@ static bus_addr_t add_bounce_page(bus_dma_tag_t dmat,
vm_offset_t vaddr, bus_addr_t addr, bus_size_t size);
static void free_bounce_page(bus_dma_tag_t dmat, struct bounce_page *bpage);
int run_filter(bus_dma_tag_t dmat, bus_addr_t paddr);
-static bool _bus_dmamap_pagesneeded(bus_dma_tag_t dmat, vm_paddr_t buf,
- bus_size_t buflen, int *pagesneeded);
+static bool _bus_dmamap_pagesneeded(bus_dma_tag_t dmat, bus_dmamap_t map,
+ vm_paddr_t buf, bus_size_t buflen, int *pagesneeded);
static void _bus_dmamap_count_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
pmap_t pmap, void *buf, bus_size_t buflen, int flags);
static void _bus_dmamap_count_phys(bus_dma_tag_t dmat, bus_dmamap_t map,
@@ -164,20 +165,70 @@ static void _bus_dmamap_count_phys(bus_dma_tag_t dmat,
static int _bus_dmamap_reserve_pages(bus_dma_tag_t dmat, bus_dmamap_t map,
int flags);
+/*
+ * Return true if the DMA should bounce because the start or end does not fall
+ * on a cacheline boundary (which would require a partial cacheline flush).
+ * COHERENT memory doesn't trigger cacheline flushes. Memory allocated by
+ * bus_dmamem_alloc() is always aligned to cacheline boundaries, and there's a
+ * strict rule that such memory cannot be accessed by the CPU while DMA is in
+ * progress (or by multiple DMA engines at once), so that it's always safe to do
+ * full cacheline flushes even if that affects memory outside the range of a
+ * given DMA operation that doesn't involve the full allocated buffer. If we're
+ * mapping an mbuf, that follows the same rules as a buffer we allocated.
+ */
static bool
-might_bounce(bus_dma_tag_t dmat)
+cacheline_bounce(bus_dma_tag_t dmat, bus_dmamap_t map, bus_addr_t paddr,
+ bus_size_t size)
{
+#define DMAMAP_CACHELINE_FLAGS \
+ (DMAMAP_FROM_DMAMEM | DMAMAP_COHERENT | DMAMAP_MBUF)
+ if ((dmat->bounce_flags & BF_COHERENT) != 0)
+ return (false);
+ if (map != NULL && (map->flags & DMAMAP_CACHELINE_FLAGS) != 0)
+ return (false);
+ return (((paddr | size) & (dcache_line_size - 1)) != 0);
+#undef DMAMAP_CACHELINE_FLAGS
+}
+
+/*
+ * Return true if the given address does not fall on the alignment boundary.
+ */
+static bool
+alignment_bounce(bus_dma_tag_t dmat, bus_addr_t addr)
+{
+
+ return ((addr & (dmat->common.alignment - 1)) != 0);
+}
+
+static bool
+might_bounce(bus_dma_tag_t dmat, bus_dmamap_t map, bus_addr_t paddr,
+ bus_size_t size)
+{
+
if ((dmat->bounce_flags & BF_COULD_BOUNCE) != 0)
return (true);
+ if (cacheline_bounce(dmat, map, paddr, size))
+ return (true);
+
+ if (alignment_bounce(dmat, paddr))
+ return (true);
+
return (false);
}
static bool
-must_bounce(bus_dma_tag_t dmat, bus_addr_t paddr)
+must_bounce(bus_dma_tag_t dmat, bus_dmamap_t map, bus_addr_t paddr,
+ bus_size_t size)
{
+ if (cacheline_bounce(dmat, map, paddr, size))
+ return (true);
+
+ if (alignment_bounce(dmat, paddr))
+ return (true);
+
if ((dmat->bounce_flags & BF_COULD_BOUNCE) != 0 &&
bus_dma_run_filter(&dmat->common, paddr))
return (true);
@@ -240,8 +291,7 @@ bounce_bus_dma_tag_create(bus_dma_tag_t parent, bus_si
newtag->common.alignment > 1)
newtag->bounce_flags |= BF_COULD_BOUNCE;
- if (((newtag->bounce_flags & BF_COULD_BOUNCE) != 0) &&
- (flags & BUS_DMA_ALLOCNOW) != 0) {
+ if ((flags & BUS_DMA_ALLOCNOW) != 0) {
struct bounce_zone *bz;
/* Must bounce */
@@ -315,9 +365,9 @@ static bool
bounce_bus_dma_id_mapped(bus_dma_tag_t dmat, vm_paddr_t buf, bus_size_t buflen)
{
- if (!might_bounce(dmat))
+ if (!might_bounce(dmat, NULL, buf, buflen))
return (true);
- return (!_bus_dmamap_pagesneeded(dmat, buf, buflen, NULL));
+ return (!_bus_dmamap_pagesneeded(dmat, NULL, buf, buflen, NULL));
}
static bus_dmamap_t
@@ -373,43 +423,39 @@ bounce_bus_dmamap_create(bus_dma_tag_t dmat, int flags
* exclusion region, a data alignment that is stricter than 1, and/or
* an active address boundary.
*/
- if (dmat->bounce_flags & BF_COULD_BOUNCE) {
- /* Must bounce */
- if (dmat->bounce_zone == NULL) {
- if ((error = alloc_bounce_zone(dmat)) != 0) {
- free(*mapp, M_DEVBUF);
- return (error);
- }
+ if (dmat->bounce_zone == NULL) {
+ if ((error = alloc_bounce_zone(dmat)) != 0) {
+ free(*mapp, M_DEVBUF);
+ return (error);
}
- bz = dmat->bounce_zone;
+ }
+ bz = dmat->bounce_zone;
- /*
- * Attempt to add pages to our pool on a per-instance
- * basis up to a sane limit.
- */
- if (dmat->common.alignment > 1)
- maxpages = MAX_BPAGES;
- else
- maxpages = MIN(MAX_BPAGES, Maxmem -
- atop(dmat->common.lowaddr));
- if ((dmat->bounce_flags & BF_MIN_ALLOC_COMP) == 0 ||
- (bz->map_count > 0 && bz->total_bpages < maxpages)) {
- pages = MAX(atop(dmat->common.maxsize), 1);
- pages = MIN(maxpages - bz->total_bpages, pages);
- pages = MAX(pages, 1);
- if (alloc_bounce_pages(dmat, pages) < pages)
- error = ENOMEM;
- if ((dmat->bounce_flags & BF_MIN_ALLOC_COMP)
- == 0) {
- if (error == 0) {
- dmat->bounce_flags |=
- BF_MIN_ALLOC_COMP;
- }
- } else
- error = 0;
- }
- bz->map_count++;
+ /*
+ * Attempt to add pages to our pool on a per-instance
+ * basis up to a sane limit.
+ */
+ if (dmat->common.alignment > 1)
+ maxpages = MAX_BPAGES;
+ else
+ maxpages = MIN(MAX_BPAGES, Maxmem -
+ atop(dmat->common.lowaddr));
+ if ((dmat->bounce_flags & BF_MIN_ALLOC_COMP) == 0 ||
+ (bz->map_count > 0 && bz->total_bpages < maxpages)) {
+ pages = MAX(atop(dmat->common.maxsize), 1);
+ pages = MIN(maxpages - bz->total_bpages, pages);
+ pages = MAX(pages, 1);
+ if (alloc_bounce_pages(dmat, pages) < pages)
+ error = ENOMEM;
+ if ((dmat->bounce_flags & BF_MIN_ALLOC_COMP) == 0) {
+ if (error == 0) {
+ dmat->bounce_flags |= BF_MIN_ALLOC_COMP;
+ }
+ } else
+ error = 0;
}
+ bz->map_count++;
+
if (error == 0) {
dmat->map_count++;
if ((dmat->bounce_flags & BF_COHERENT) != 0)
@@ -595,8 +641,8 @@ bounce_bus_dmamem_free(bus_dma_tag_t dmat, void *vaddr
}
static bool
-_bus_dmamap_pagesneeded(bus_dma_tag_t dmat, vm_paddr_t buf, bus_size_t buflen,
- int *pagesneeded)
+_bus_dmamap_pagesneeded(bus_dma_tag_t dmat, bus_dmamap_t map, vm_paddr_t buf,
+ bus_size_t buflen, int *pagesneeded)
{
bus_addr_t curaddr;
bus_size_t sgsize;
@@ -610,7 +656,7 @@ _bus_dmamap_pagesneeded(bus_dma_tag_t dmat, vm_paddr_t
curaddr = buf;
while (buflen != 0) {
sgsize = MIN(buflen, dmat->common.maxsegsz);
- if (must_bounce(dmat, curaddr)) {
+ if (must_bounce(dmat, map, curaddr, sgsize)) {
sgsize = MIN(sgsize,
PAGE_SIZE - (curaddr & PAGE_MASK));
if (pagesneeded == NULL)
@@ -632,7 +678,8 @@ _bus_dmamap_count_phys(bus_dma_tag_t dmat, bus_dmamap_
{
if (map->pagesneeded == 0) {
- _bus_dmamap_pagesneeded(dmat, buf, buflen, &map->pagesneeded);
+ _bus_dmamap_pagesneeded(dmat, map, buf, buflen,
+ &map->pagesneeded);
CTR1(KTR_BUSDMA, "pagesneeded= %d\n", map->pagesneeded);
}
}
@@ -666,7 +713,9 @@ _bus_dmamap_count_pages(bus_dma_tag_t dmat, bus_dmamap
paddr = pmap_kextract(vaddr);
else
paddr = pmap_extract(pmap, vaddr);
- if (must_bounce(dmat, paddr)) {
+ if (must_bounce(dmat, map, paddr,
+ min(vendaddr - vaddr, (PAGE_SIZE - ((vm_offset_t)vaddr &
+ PAGE_MASK)))) != 0) {
sg_len = roundup2(sg_len,
dmat->common.alignment);
map->pagesneeded++;
@@ -764,7 +813,7 @@ bounce_bus_dmamap_load_phys(bus_dma_tag_t dmat, bus_dm
if (segs == NULL)
segs = dmat->segments;
- if (might_bounce(dmat)) {
+ if (might_bounce(dmat, map, (bus_addr_t)buf, buflen)) {
_bus_dmamap_count_phys(dmat, map, buf, buflen, flags);
if (map->pagesneeded != 0) {
error = _bus_dmamap_reserve_pages(dmat, map, flags);
@@ -779,7 +828,8 @@ bounce_bus_dmamap_load_phys(bus_dma_tag_t dmat, bus_dm
while (buflen > 0) {
curaddr = buf;
sgsize = MIN(buflen, dmat->common.maxsegsz);
- if (map->pagesneeded != 0 && must_bounce(dmat, curaddr)) {
+ if (map->pagesneeded != 0 &&
+ must_bounce(dmat, map, curaddr, sgsize)) {
sgsize = MIN(sgsize, PAGE_SIZE - (curaddr & PAGE_MASK));
curaddr = add_bounce_page(dmat, map, 0, curaddr,
sgsize);
@@ -833,7 +883,10 @@ bounce_bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_
if (segs == NULL)
segs = dmat->segments;
- if (might_bounce(dmat)) {
+ if (flags & BUS_DMA_LOAD_MBUF)
+ map->flags |= DMAMAP_MBUF;
+
+ if (might_bounce(dmat, map, (bus_addr_t)buf, buflen)) {
_bus_dmamap_count_pages(dmat, map, pmap, buf, buflen, flags);
if (map->pagesneeded != 0) {
error = _bus_dmamap_reserve_pages(dmat, map, flags);
@@ -864,7 +917,8 @@ bounce_bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_
*/
max_sgsize = MIN(buflen, dmat->common.maxsegsz);
sgsize = PAGE_SIZE - (curaddr & PAGE_MASK);
- if (map->pagesneeded != 0 && must_bounce(dmat, curaddr)) {
+ if (map->pagesneeded != 0 &&
+ must_bounce(dmat, map, curaddr, sgsize)) {
sgsize = roundup2(sgsize, dmat->common.alignment);
sgsize = MIN(sgsize, max_sgsize);
curaddr = add_bounce_page(dmat, map, kvaddr, curaddr,
@@ -949,6 +1003,7 @@ bounce_bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmama
}
map->sync_count = 0;
+ map->flags &= ~DMAMAP_MBUF;
}
static void
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