Date: Thu, 31 Jan 2013 21:24:27 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: arm@freebsd.org Subject: bud_dmamap_load_buffer() Message-ID: <20130131192426.GL2522@kib.kiev.ua>
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I noted that arm/busdma_machdep.c uses essentially inlined pmap_kextract()
to get the physical address from the kernel address. I consulted with
gonzo, who said that he does not see a reason for inlining the code.
My theory is that before r240983, pmap_kextract() locked the pmap, which
caused unneeded and probably wrong locking in the busdma load path. Since
this issue is fixed, I see no reason for directly walking the page tables.
Could somebody please review and test the patch ? v6 busdma already uses
pmap_kextract().
Do not remove me from Cc:.
diff --git a/sys/arm/arm/busdma_machdep.c b/sys/arm/arm/busdma_machdep.c
index 42566e8..8f49300 100644
--- a/sys/arm/arm/busdma_machdep.c
+++ b/sys/arm/arm/busdma_machdep.c
@@ -849,9 +849,6 @@ bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_dma_segm=
ent_t *segs,
vm_offset_t vaddr =3D (vm_offset_t)buf;
int seg;
int error =3D 0;
- pd_entry_t *pde;
- pt_entry_t pte;
- pt_entry_t *ptep;
=20
lastaddr =3D *lastaddrp;
bmask =3D ~(dmat->boundary - 1);
@@ -873,29 +870,7 @@ bus_dmamap_load_buffer(bus_dma_tag_t dmat, bus_dma_seg=
ment_t *segs,
* XXX in user address space.
*/
if (__predict_true(pmap =3D=3D pmap_kernel())) {
- if (pmap_get_pde_pte(pmap, vaddr, &pde, &ptep) =3D=3D FALSE)
- return (EFAULT);
-
- if (__predict_false(pmap_pde_section(pde))) {
- if (*pde & L1_S_SUPERSEC)
- curaddr =3D (*pde & L1_SUP_FRAME) |
- (vaddr & L1_SUP_OFFSET);
- else
- curaddr =3D (*pde & L1_S_FRAME) |
- (vaddr & L1_S_OFFSET);
- } else {
- pte =3D *ptep;
- KASSERT((pte & L2_TYPE_MASK) !=3D L2_TYPE_INV,
- ("INV type"));
- if (__predict_false((pte & L2_TYPE_MASK)
- =3D=3D L2_TYPE_L)) {
- curaddr =3D (pte & L2_L_FRAME) |
- (vaddr & L2_L_OFFSET);
- } else {
- curaddr =3D (pte & L2_S_FRAME) |
- (vaddr & L2_S_OFFSET);
- }
- }
+ curaddr =3D pmap_kextract(vaddr);
} else {
curaddr =3D pmap_extract(pmap, vaddr);
map->flags &=3D ~DMAMAP_COHERENT;
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