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, 6 deletions

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index c7584072dfcc..2001abdb1912 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -145,13 +145,20 @@ void pte_free(struct mm_struct *mm, pgtable_t ptepage)
 void __iomem *
 ioremap(phys_addr_t addr, unsigned long size)
 {
-        return __ioremap(addr, size, _PAGE_NO_CACHE);
+        return __ioremap(addr, size, _PAGE_NO_CACHE | _PAGE_GUARDED);
 }
 EXPORT_SYMBOL(ioremap);
 
 void __iomem *
 ioremap_flags(phys_addr_t addr, unsigned long size, unsigned long flags)
 {
+        /* writeable implies dirty for kernel addresses */
+        if (flags & _PAGE_RW)
+                flags |= _PAGE_DIRTY | _PAGE_HWWRITE;
+
+        /* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
+        flags &= ~(_PAGE_USER | _PAGE_EXEC | _PAGE_HWEXEC);
+
         return __ioremap(addr, size, flags);
 }
 EXPORT_SYMBOL(ioremap_flags);
@@ -163,6 +170,14 @@ __ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
         phys_addr_t p;
         int err;
 
+        /* Make sure we have the base flags */
+        if ((flags & _PAGE_PRESENT) == 0)
+                flags |= _PAGE_KERNEL;
+
+        /* Non-cacheable page cannot be coherent */
+        if (flags & _PAGE_NO_CACHE)
+                flags &= ~_PAGE_COHERENT;
+
         /*
          * Choose an address to map it to.
          * Once the vmalloc system is running, we use it.
@@ -219,11 +234,6 @@ __ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
                 v = (ioremap_bot -= size);
         }
 
-        if ((flags & _PAGE_PRESENT) == 0)
-                flags |= _PAGE_KERNEL;
-        if (flags & _PAGE_NO_CACHE)
-                flags |= _PAGE_GUARDED;
-
         /*
          * Should check if it is a candidate for a BAT mapping
          */