Add pmap function pmap_copy_pages(), which copies the content of the

pages around, taking array of vm_page_t both for source and
destination.  Starting offsets and total transfer size are specified.

The function implements optimal algorithm for copying using the
platform-specific optimizations.  For instance, on the architectures
were the direct map is available, no transient mappings are created,
for i386 the per-cpu ephemeral page frame is used.  The code was
typically borrowed from the pmap_copy_page() for the same
architecture.

Only i386/amd64, powerpc aim and arm/arm-v6 implementations were
tested at the time of commit. High-level code, not committed yet to
the tree, ensures that the use of the function is only allowed after
explicit enablement.

For sparc64, the existing code has known issues and a stab is added
instead, to allow the kernel linking.

Sponsored by:	The FreeBSD Foundation
Tested by:	pho (i386, amd64), scottl (amd64), ian (arm and arm-v6)
MFC after:	2 weeks

1 files changed, 24 insertions, 0 deletions

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index aa38013..4777c08 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -4272,6 +4272,30 @@ pmap_copy_page(vm_page_t msrc, vm_page_t mdst)
 	pagecopy((void *)src, (void *)dst);
 }
 
+void
+pmap_copy_pages(vm_page_t ma[], vm_offset_t a_offset, vm_page_t mb[],
+    vm_offset_t b_offset, int xfersize)
+{
+	void *a_cp, *b_cp;
+	vm_offset_t a_pg_offset, b_pg_offset;
+	int cnt;
+
+	while (xfersize > 0) {
+		a_pg_offset = a_offset & PAGE_MASK;
+		cnt = min(xfersize, PAGE_SIZE - a_pg_offset);
+		a_cp = (char *)PHYS_TO_DMAP(ma[a_offset >> PAGE_SHIFT]->
+		    phys_addr) + a_pg_offset;
+		b_pg_offset = b_offset & PAGE_MASK;
+		cnt = min(cnt, PAGE_SIZE - b_pg_offset);
+		b_cp = (char *)PHYS_TO_DMAP(mb[b_offset >> PAGE_SHIFT]->
+		    phys_addr) + b_pg_offset;
+		bcopy(a_cp, b_cp, cnt);
+		a_offset += cnt;
+		b_offset += cnt;
+		xfersize -= cnt;
+	}
+}
+
 /*
  * Returns true if the pmap's pv is one of the first
  * 16 pvs linked to from this page.  This count may