The page flag PGA_WRITEABLE is set and cleared exclusively by the pmap

layer, but it is read directly by the MI VM layer.  This change introduces
pmap_page_is_write_mapped() in order to completely encapsulate all direct
access to PGA_WRITEABLE in the pmap layer.

Aesthetics aside, I am making this change because amd64 will likely begin
using an alternative method to track write mappings, and having
pmap_page_is_write_mapped() in place allows me to make such a change
without further modification to the MI VM layer.

As an added bonus, tidy up some nearby comments concerning page flags.

Reviewed by:	kib
MFC after:	6 weeks

1 files changed, 2 insertions, 0 deletions

diff --git a/sys/powerpc/include/pmap.h b/sys/powerpc/include/pmap.h
index 2f0e5b0..f50ff11 100644
--- a/sys/powerpc/include/pmap.h
+++ b/sys/powerpc/include/pmap.h
@@ -223,6 +223,8 @@ extern	struct pmap kernel_pmap_store;
 #define	PMAP_TRYLOCK(pmap)	mtx_trylock(&(pmap)->pm_mtx)
 #define	PMAP_UNLOCK(pmap)	mtx_unlock(&(pmap)->pm_mtx)
 
+#define	pmap_page_is_write_mapped(m)	(((m)->aflags & PGA_WRITEABLE) != 0)
+
 void		pmap_bootstrap(vm_offset_t, vm_offset_t);
 void		pmap_kenter(vm_offset_t va, vm_paddr_t pa);
 void		pmap_kenter_attr(vm_offset_t va, vm_offset_t pa, vm_memattr_t);