powerpc ioremap_prot

This adds ioremap_prot and pte_pgprot() so that one can extract protection
bits from a PTE and use them to ioremap_prot() (in order to support ptrace
of VM_IO | VM_PFNMAP as per Rik's patch).

This moves a couple of flag checks around in the ioremap implementations
of arch/powerpc.  There's a side effect of allowing non-cacheable and
non-guarded mappings on ppc32 which before would always have _PAGE_GUARDED
set whenever _PAGE_NO_CACHE is.

(standard ioremap will still set _PAGE_GUARDED, but ioremap_prot will be
capable of setting such a non guarded mapping).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/asm-powerpc/pgtable-ppc64.h b/include/asm-powerpc/pgtable-ppc64.h
index ab98a9c80b28..ba8000352b9a 100644
--- a/include/asm-powerpc/pgtable-ppc64.h
+++ b/include/asm-powerpc/pgtable-ppc64.h
@@ -117,6 +117,10 @@
 #define PAGE_AGP        __pgprot(_PAGE_BASE | _PAGE_WRENABLE | _PAGE_NO_CACHE)
 #define HAVE_PAGE_AGP
 
+#define PAGE_PROT_BITS  __pgprot(_PAGE_GUARDED | _PAGE_COHERENT | \
+                                 _PAGE_NO_CACHE | _PAGE_WRITETHRU | \
+                                 _PAGE_4K_PFN | _PAGE_RW | _PAGE_USER | \
+                                 _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_EXEC)
 /* PTEIDX nibble */
 #define _PTEIDX_SECONDARY       0x8
 #define _PTEIDX_GROUP_IX        0x7
@@ -262,6 +266,10 @@ static inline pte_t pte_mkhuge(pte_t pte) {
         return pte; }
 static inline pte_t pte_mkspecial(pte_t pte) {
         return pte; }
+static inline unsigned long pte_pgprot(pte_t pte)
+{
+        return __pgprot(pte_val(pte)) & PAGE_PROT_BITS;
+}
 
 /* Atomic PTE updates */
 static inline unsigned long pte_update(struct mm_struct *mm,