[PATCH] powerpc/mm: Fix 40x and 8xx vs. _PAGE_SPECIAL

[Weirich, Bernhard]

Works perfectly here. Thank you for the patch, I was not feeling confident enough to play around with the page bits :)

Bernhard WEIRICH
Software Development
________________________________________
Von: Benjamin Herrenschmidt [benh at kernel.crashing.org]
Gesendet: Mittwoch, 23. September 2009 06:12
An: Weirich, Bernhard; Rex Feany
Cc: linuxppc-dev list
Betreff: [PATCH] powerpc/mm: Fix 40x and 8xx vs. _PAGE_SPECIAL

The test to check whether we have _PAGE_SPECIAL defined is broken,
since we always define it, just not always to a meaninful value :-)

That broke 8xx and 40x under some circumstances.

This fixes it by adding _PAGE_SPECIAL for both of these since they
had a free PTE bit, and removing the condition around advertising
it.

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

Bernhard, Rex, please let me know if that works for you.


diff --git a/arch/powerpc/include/asm/pte-40x.h b/arch/powerpc/include/asm/pte-40x.h
index 6c3e1f4..ec0b0b0 100644
--- a/arch/powerpc/include/asm/pte-40x.h
+++ b/arch/powerpc/include/asm/pte-40x.h
@@ -43,6 +43,7 @@
 #define        _PAGE_NO_CACHE  0x004   /* I: caching is inhibited */
 #define        _PAGE_WRITETHRU 0x008   /* W: caching is write-through */
 #define        _PAGE_USER      0x010   /* matches one of the zone permission bits */
+#define        _PAGE_SPECIAL   0x020   /* software: Special page */
 #define        _PAGE_RW        0x040   /* software: Writes permitted */
 #define        _PAGE_DIRTY     0x080   /* software: dirty page */
 #define _PAGE_HWWRITE  0x100   /* hardware: Dirty & RW, set in exception */
diff --git a/arch/powerpc/include/asm/pte-8xx.h b/arch/powerpc/include/asm/pte-8xx.h
index 94e9797..dd5ea95 100644
--- a/arch/powerpc/include/asm/pte-8xx.h
+++ b/arch/powerpc/include/asm/pte-8xx.h
@@ -32,6 +32,7 @@
 #define _PAGE_FILE     0x0002  /* when !present: nonlinear file mapping */
 #define _PAGE_NO_CACHE 0x0002  /* I: cache inhibit */
 #define _PAGE_SHARED   0x0004  /* No ASID (context) compare */
+#define _PAGE_SPECIAL  0x0008  /* SW entry, forced to 0 by the TLB miss */

 /* These five software bits must be masked out when the entry is loaded
  * into the TLB.
diff --git a/arch/powerpc/include/asm/pte-common.h b/arch/powerpc/include/asm/pte-common.h
index c3b6507..f2b3701 100644
--- a/arch/powerpc/include/asm/pte-common.h
+++ b/arch/powerpc/include/asm/pte-common.h
@@ -25,9 +25,6 @@
 #ifndef _PAGE_WRITETHRU
 #define _PAGE_WRITETHRU        0
 #endif
-#ifndef _PAGE_SPECIAL
-#define _PAGE_SPECIAL  0
-#endif
 #ifndef _PAGE_4K_PFN
 #define _PAGE_4K_PFN           0
 #endif
@@ -179,7 +176,5 @@ extern unsigned long bad_call_to_PMD_PAGE_SIZE(void);
 #define HAVE_PAGE_AGP

 /* Advertise support for _PAGE_SPECIAL */
-#ifdef _PAGE_SPECIAL
 #define __HAVE_ARCH_PTE_SPECIAL
-#endif