powerpc/mm: Tweak PTE bit combination definitions

This patch tweaks the way some PTE bit combinations are defined, in such a
way that the 32 and 64-bit variant become almost identical and that will
make it easier to bring in a new common pte-* file for the new variant
of the Book3-E support.

The combination of bits defining access to kernel pages are now clearly
separated from the combination used by userspace and the core VM. The
resulting generated code should remain identical unless I made a mistake.

Note: While at it, I removed a non-sensical statement related to CONFIG_KGDB
in ppc_mmu_32.c which could cause kernel mappings to be user accessible when
that option is enabled. Probably something that bitrot.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 29 insertions, 17 deletions

diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h
index 5420738..5a575f2 100644
--- a/arch/powerpc/include/asm/pgtable-ppc64.h
+++ b/arch/powerpc/include/asm/pgtable-ppc64.h
@@ -81,11 +81,6 @@
  */
 #include <asm/pte-hash64.h>
 
-/* To make some generic powerpc code happy */
-#ifndef _PAGE_HWEXEC
-#define _PAGE_HWEXEC		0
-#endif
-
 /* Some other useful definitions */
 #define PTE_RPN_MAX	(1UL << (64 - PTE_RPN_SHIFT))
 #define PTE_RPN_MASK	(~((1UL<<PTE_RPN_SHIFT)-1))
@@ -96,28 +91,44 @@
 #define _PAGE_CHG_MASK	(PTE_RPN_MASK | _PAGE_HPTEFLAGS | _PAGE_DIRTY | \
                          _PAGE_ACCESSED | _PAGE_SPECIAL)
 
+#define _PAGE_BASE_NC	(_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_PSIZE)
+#define _PAGE_BASE	(_PAGE_BASE_NC | _PAGE_COHERENT)
 
 
-/* __pgprot defined in arch/powerpc/include/asm/page.h */
-#define PAGE_NONE	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED)
-
-#define PAGE_SHARED	__pgprot(_PAGE_BASE | _PAGE_RW | _PAGE_USER)
-#define PAGE_SHARED_X	__pgprot(_PAGE_BASE | _PAGE_RW | _PAGE_USER | _PAGE_EXEC)
+/* Permission masks used to generate the __P and __S table,
+ *
+ * Note:__pgprot is defined in arch/powerpc/include/asm/page.h
+ */
+#define PAGE_NONE	__pgprot(_PAGE_BASE)
+#define PAGE_SHARED	__pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW)
+#define PAGE_SHARED_X	__pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_RW | _PAGE_EXEC)
 #define PAGE_COPY	__pgprot(_PAGE_BASE | _PAGE_USER)
 #define PAGE_COPY_X	__pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
 #define PAGE_READONLY	__pgprot(_PAGE_BASE | _PAGE_USER)
 #define PAGE_READONLY_X	__pgprot(_PAGE_BASE | _PAGE_USER | _PAGE_EXEC)
-#define PAGE_KERNEL	__pgprot(_PAGE_BASE | _PAGE_WRENABLE)
-#define PAGE_KERNEL_CI	__pgprot(_PAGE_PRESENT | _PAGE_ACCESSED | \
-			       _PAGE_WRENABLE | _PAGE_NO_CACHE | _PAGE_GUARDED)
-#define PAGE_KERNEL_EXEC __pgprot(_PAGE_BASE | _PAGE_WRENABLE | _PAGE_EXEC)
 
-#define PAGE_AGP	__pgprot(_PAGE_BASE | _PAGE_WRENABLE | _PAGE_NO_CACHE)
-#define HAVE_PAGE_AGP
+/* Permission masks used for kernel mappings */
+#define PAGE_KERNEL	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RW)
+#define PAGE_KERNEL_NC	__pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | \
+				 _PAGE_NO_CACHE)
+#define PAGE_KERNEL_NCG	__pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | \
+				 _PAGE_NO_CACHE | _PAGE_GUARDED)
+#define PAGE_KERNEL_X __pgprot(_PAGE_BASE | _PAGE_KERNEL_RW | _PAGE_EXEC)
+#define PAGE_KERNEL_RO __pgprot(_PAGE_BASE | _PAGE_KERNEL_RO)
+#define PAGE_KERNEL_ROX __pgprot(_PAGE_BASE | _PAGE_KERNEL_RO | _PAGE_EXEC)
+
+/* Protection bits for use by pte_pgprot() */
+#define PAGE_PROT_BITS	(_PAGE_GUARDED | _PAGE_COHERENT | \
+			 _PAGE_NO_CACHE | _PAGE_WRITETHRU |		\
+			 _PAGE_4K_PFN | _PAGE_USER | _PAGE_RW |		\
+			 _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_EXEC)
+
 
 /* We always have _PAGE_SPECIAL on 64 bit */
 #define __HAVE_ARCH_PTE_SPECIAL
 
+/* Make modules code happy. We don't set RO yet */
+#define PAGE_KERNEL_EXEC	PAGE_KERNEL_X
 
 /*
  * POWER4 and newer have per page execute protection, older chips can only
@@ -395,7 +406,8 @@ static inline void pte_clear(struct mm_struct *mm, unsigned long addr,
 static inline void __ptep_set_access_flags(pte_t *ptep, pte_t entry)
 {
 	unsigned long bits = pte_val(entry) &
-		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);
+		(_PAGE_DIRTY | _PAGE_ACCESSED | _PAGE_RW |
+		 _PAGE_EXEC | _PAGE_HWEXEC);
 	unsigned long old, tmp;
 
 	__asm__ __volatile__(