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, 16 insertions, 0 deletions

diff --git a/include/asm-powerpc/pgtable-ppc32.h b/include/asm-powerpc/pgtable-ppc32.h
index 3a96d001cb75..bdbab72f3ebc 100644
--- a/include/asm-powerpc/pgtable-ppc32.h
+++ b/include/asm-powerpc/pgtable-ppc32.h
@@ -395,6 +395,12 @@ extern int icache_44x_need_flush;
 #ifndef _PAGE_EXEC
 #define _PAGE_EXEC      0
 #endif
+#ifndef _PAGE_ENDIAN
+#define _PAGE_ENDIAN    0
+#endif
+#ifndef _PAGE_COHERENT
+#define _PAGE_COHERENT  0
+#endif
 #ifndef _PMD_PRESENT_MASK
 #define _PMD_PRESENT_MASK       _PMD_PRESENT
 #endif
@@ -405,6 +411,12 @@ extern int icache_44x_need_flush;
 
 #define _PAGE_CHG_MASK  (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
 
+
+#define PAGE_PROT_BITS  __pgprot(_PAGE_GUARDED | _PAGE_COHERENT | _PAGE_NO_CACHE | \
+                                 _PAGE_WRITETHRU | _PAGE_ENDIAN | \
+                                 _PAGE_USER | _PAGE_ACCESSED | \
+                                 _PAGE_RW | _PAGE_HWWRITE | _PAGE_DIRTY | \
+                                 _PAGE_EXEC | _PAGE_HWEXEC)
 /*
  * Note: the _PAGE_COHERENT bit automatically gets set in the hardware
  * PTE if CONFIG_SMP is defined (hash_page does this); there is no need
@@ -538,6 +550,10 @@ static inline pte_t pte_mkyoung(pte_t pte) {
         pte_val(pte) |= _PAGE_ACCESSED; 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;
+}
 
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {