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, 2 insertions, 0 deletions

diff --git a/sys/vm/pmap.h b/sys/vm/pmap.h
index d73babc..741ba3c 100644
--- a/sys/vm/pmap.h
+++ b/sys/vm/pmap.h
@@ -152,6 +152,8 @@ void		 pmap_unwire(pmap_t pmap, vm_offset_t start, vm_offset_t end);
 void		 pmap_zero_page(vm_page_t);
 void		 pmap_zero_page_area(vm_page_t, int off, int size);
 void		 pmap_zero_page_idle(vm_page_t);
+vm_offset_t	 pmap_quick_enter_page(vm_page_t);
+void		 pmap_quick_remove_page(vm_offset_t);
 
 #define	pmap_resident_count(pm)	((pm)->pm_stats.resident_count)
 #define	pmap_wired_count(pm)	((pm)->pm_stats.wired_count)