git: f635cef2a420 - main - arm64 busdma: Fix loading of small bounced buffers.

[Michal Meloun]

The branch main has been updated by mmel:

URL: https://cgit.FreeBSD.org/src/commit/?id=f635cef2a4206fb4e077412c493f218a6a26a3da

commit f635cef2a4206fb4e077412c493f218a6a26a3da
Author:     Michal Meloun <mmel at FreeBSD.org>
AuthorDate: 2021-01-13 12:50:54 +0000
Commit:     Michal Meloun <mmel at FreeBSD.org>
CommitDate: 2021-01-19 12:09:17 +0000

    arm64 busdma: Fix loading of small bounced buffers.
    
     - Don't oversize the buffer fragment. PAGE_SIZE - (curaddr & PAGE_MASK)
       may be greater than the total length of the buffer.
     - Don't use roundup2(len, alignment) to calculate the buffer fragment
       size. The length of current bounced fragment is not subject to alignment
       restriction, and next fragment should start at the page boundary.
    
    Tested by:      bz, s199p.wa1k9r at gmail.com
---
 sys/arm64/arm64/busdma_bounce.c | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/sys/arm64/arm64/busdma_bounce.c b/sys/arm64/arm64/busdma_bounce.c
index 70e626372df8..d2e63d7b72d8 100644
--- a/sys/arm64/arm64/busdma_bounce.c
+++ b/sys/arm64/arm64/busdma_bounce.c
@@ -845,9 +845,7 @@ bounce_bus_dmamap_load_phys(bus_dma_tag_t dmat, bus_dmamap_t map,
 			KASSERT(dmat->common.alignment <= PAGE_SIZE,
 			    ("bounced buffer cannot have alignment bigger "
 			    "than PAGE_SIZE: %lu", dmat->common.alignment));
-			sgsize = PAGE_SIZE - (curaddr & PAGE_MASK);
-			sgsize = roundup2(sgsize, dmat->common.alignment);
-			sgsize = MIN(sgsize, dmat->common.maxsegsz);
+			sgsize = MIN(sgsize, PAGE_SIZE - (curaddr & PAGE_MASK));
 			curaddr = add_bounce_page(dmat, map, 0, curaddr,
 			    sgsize);
 		} else if ((map->flags & DMAMAP_COHERENT) == 0) {
@@ -879,7 +877,11 @@ bounce_bus_dmamap_load_phys(bus_dma_tag_t dmat, bus_dmamap_t map,
 	/*
 	 * Did we fit?
 	 */
-	return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
+	if (buflen != 0) {
+		bus_dmamap_unload(dmat, map);
+		return (EFBIG); /* XXX better return value here? */
+	}
+	return (0);
 }
 
 /*
@@ -892,7 +894,7 @@ bounce_bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
     int *segp)
 {
 	struct sync_list *sl;
-	bus_size_t sgsize, max_sgsize;
+	bus_size_t sgsize;
 	bus_addr_t curaddr, sl_pend;
 	vm_offset_t kvaddr, vaddr, sl_vend;
 	int error;
@@ -931,7 +933,7 @@ bounce_bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
 		/*
 		 * Get the physical address for this segment.
 		 */
-		if (pmap == kernel_pmap) {
+		if (__predict_true(pmap == kernel_pmap)) {
 			curaddr = pmap_kextract(vaddr);
 			kvaddr = vaddr;
 		} else {
@@ -942,13 +944,9 @@ bounce_bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
 		/*
 		 * Compute the segment size, and adjust counts.
 		 */
-		max_sgsize = MIN(buflen, dmat->common.maxsegsz);
-		if ((map->flags & DMAMAP_FROM_DMAMEM) != 0) {
-			sgsize = max_sgsize;
-		} else {
-			sgsize = PAGE_SIZE - (curaddr & PAGE_MASK);
-			sgsize = MIN(sgsize, max_sgsize);
-		}
+		sgsize = MIN(buflen, dmat->common.maxsegsz);
+		if ((map->flags & DMAMAP_FROM_DMAMEM) == 0)
+			sgsize = MIN(sgsize, PAGE_SIZE - (curaddr & PAGE_MASK));
 
 		if (map->pagesneeded != 0 &&
 		    must_bounce(dmat, map, curaddr, sgsize)) {
@@ -956,9 +954,6 @@ bounce_bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
 			KASSERT(dmat->common.alignment <= PAGE_SIZE,
 			    ("bounced buffer cannot have alignment bigger "
 			    "than PAGE_SIZE: %lu", dmat->common.alignment));
-			sgsize = PAGE_SIZE - (curaddr & PAGE_MASK);
-			sgsize = roundup2(sgsize, dmat->common.alignment);
-			sgsize = MIN(sgsize, max_sgsize);
 			curaddr = add_bounce_page(dmat, map, kvaddr, curaddr,
 			    sgsize);
 		} else if ((map->flags & DMAMAP_COHERENT) == 0) {
@@ -999,7 +994,11 @@ bounce_bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
 	/*
 	 * Did we fit?
 	 */
-	return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
+	if (buflen != 0) {
+		bus_dmamap_unload(dmat, map);
+		return (EFBIG); /* XXX better return value here? */
+	}
+	return (0);
 }
 
 static void