From: Miklos Szeredi <mszeredi@suse.cz>
Date: Thu, 29 Mar 2007 08:20:29 +0000 (-0700)
Subject: [PATCH] uml: fix pte bit collision
X-Git-Tag: v2.6.21-rc6~64
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=602ed87ecd93a857dc687afb938d2c0f45552986;p=linux-2.6

[PATCH] uml: fix pte bit collision

_PAGE_PROTNONE conflicts with the lowest bit of pgoff.  This causes all sorts
of weirdness when nonlinear mappings are used.

Took me a good half day to track this down.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Acked-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/include/asm-um/pgtable-2level.h b/include/asm-um/pgtable-2level.h
index 6050e0eb25..172a75fde5 100644
--- a/include/asm-um/pgtable-2level.h
+++ b/include/asm-um/pgtable-2level.h
@@ -45,12 +45,12 @@ static inline void pgd_mkuptodate(pgd_t pgd)	{ }
 	((unsigned long) __va(pmd_val(pmd) & PAGE_MASK))
 
 /*
- * Bits 0 through 3 are taken
+ * Bits 0 through 4 are taken
  */
-#define PTE_FILE_MAX_BITS	28
+#define PTE_FILE_MAX_BITS	27
 
-#define pte_to_pgoff(pte) (pte_val(pte) >> 4)
+#define pte_to_pgoff(pte) (pte_val(pte) >> 5)
 
-#define pgoff_to_pte(off) ((pte_t) { ((off) << 4) + _PAGE_FILE })
+#define pgoff_to_pte(off) ((pte_t) { ((off) << 5) + _PAGE_FILE })
 
 #endif