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, 1 deletions

diff --git a/sys/i386/include/pcpu.h b/sys/i386/include/pcpu.h
index 231f80f..cfd8d03 100644
--- a/sys/i386/include/pcpu.h
+++ b/sys/i386/include/pcpu.h
@@ -58,7 +58,8 @@
 	int	pc_private_tss;		/* Flag indicating private tss*/\
 	u_int	pc_cmci_mask;		/* MCx banks for CMCI */	\
 	u_int	pc_vcpu_id;		/* Xen vCPU ID */		\
-	char	__pad[233]
+	vm_offset_t pc_qmap_addr;	/* KVA for temporary mappings */\
+	char	__pad[229]
 
 #ifdef _KERNEL