Add two new pmap functions:

vm_offset_t pmap_quick_enter_page(vm_page_t m)
void pmap_quick_remove_page(vm_offset_t kva)

These will create and destroy a temporary, CPU-local KVA mapping of a specified page.

Guarantees:
--Will not sleep and will not fail.
--Safe to call under a non-sleepable lock or from an ithread

Restrictions:
--Not guaranteed to be safe to call from an interrupt filter or under a spin mutex on all platforms
--Current implementation does not guarantee more than one page of mapping space across all platforms. MI code should not make nested calls to pmap_quick_enter_page.
--MI code should not perform locking while holding onto a mapping created by pmap_quick_enter_page

The idea is to use this in busdma, for bounce buffer copies as well as virtually-indexed cache maintenance on mips and arm.

NOTE: the non-i386, non-amd64 implementations of these functions still need review and testing.

Reviewed by:	kib
Approved by:	kib (mentor)
Differential Revision:	http://reviews.freebsd.org/D3013

1 files changed, 12 insertions, 0 deletions

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 6a3de60..780d0e3 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -6940,6 +6940,18 @@ pmap_unmap_io_transient(vm_page_t page[], vm_offset_t vaddr[], int count,
 	}
 }
 
+vm_offset_t
+pmap_quick_enter_page(vm_page_t m)
+{
+
+	return (PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m)));
+}
+
+void
+pmap_quick_remove_page(vm_offset_t addr)
+{
+}
+
 #include "opt_ddb.h"
 #ifdef DDB
 #include <ddb/ddb.h>