git: f9d85a082181 - main - Revert "x86 busdma_bounce: do not make assumptions about alignment of malloc(9) results."
Konstantin Belousov
kib at FreeBSD.org
Wed Jan 13 15:44:08 UTC 2021
The branch main has been updated by kib:
URL: https://cgit.FreeBSD.org/src/commit/?id=f9d85a082181a4eeec4200e42c3ffc1ac85f571c
commit f9d85a082181a4eeec4200e42c3ffc1ac85f571c
Author: Konstantin Belousov <kib at FreeBSD.org>
AuthorDate: 2021-01-13 15:40:54 +0000
Commit: Konstantin Belousov <kib at FreeBSD.org>
CommitDate: 2021-01-13 15:44:00 +0000
Revert "x86 busdma_bounce: do not make assumptions about alignment of malloc(9) results."
This reverts commit 8f54940f019ca586bcfbf189ef9974eeb0a8194a.
The free needs to be called on the address returned by malloc,
not the realigned address.
Noted by: andrew
Sponsored by: The FreeBSD Foundation
---
sys/x86/x86/busdma_bounce.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/sys/x86/x86/busdma_bounce.c b/sys/x86/x86/busdma_bounce.c
index fec6e2144a22..65fbbb7ec1a4 100644
--- a/sys/x86/x86/busdma_bounce.c
+++ b/sys/x86/x86/busdma_bounce.c
@@ -403,8 +403,6 @@ static int
bounce_bus_dmamem_alloc(bus_dma_tag_t dmat, void **vaddr, int flags,
bus_dmamap_t *mapp)
{
- uintptr_t ma;
- size_t malloc_sz;
vm_memattr_t attr;
int mflags;
@@ -447,20 +445,19 @@ bounce_bus_dmamem_alloc(bus_dma_tag_t dmat, void **vaddr, int flags,
* else allocate a block of contiguous pages because one or more of the
* constraints is something that only the contig allocator can fulfill.
*
- * Warn the user if we get it wrong.
+ * NOTE: The (dmat->common.alignment <= dmat->maxsize) check
+ * below is just a quick hack. The exact alignment guarantees
+ * of malloc(9) need to be nailed down, and the code below
+ * should be rewritten to take that into account.
+ *
+ * In the meantime warn the user if malloc gets it wrong.
*/
if (dmat->common.maxsize <= PAGE_SIZE &&
+ dmat->common.alignment <= dmat->common.maxsize &&
dmat->common.lowaddr >= ptoa((vm_paddr_t)Maxmem) &&
attr == VM_MEMATTR_DEFAULT) {
- malloc_sz = roundup2(dmat->common.maxsize,
- dmat->common.alignment);
- ma = (uintptr_t)malloc_domainset(malloc_sz, M_DEVBUF,
+ *vaddr = malloc_domainset(dmat->common.maxsize, M_DEVBUF,
DOMAINSET_PREF(dmat->common.domain), mflags);
- if (ma != 0) {
- *vaddr = (void *)roundup2(ma, dmat->common.alignment);
- } else {
- *vaddr = NULL;
- }
} else if (dmat->common.nsegments >=
howmany(dmat->common.maxsize, MIN(dmat->common.maxsegsz,
PAGE_SIZE)) &&
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