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[S390] protect _PAGE_SPECIAL bit against mprotect 

Stop mprotect's pte_modify from wiping out the s390 pte_special bit, which
caused oops thereafter when vm_normal_page thought X's abnormal was normal.

Debugged-by: Ryan Hope <rmh3093@gmail.com>
Debugged-by: Zan Lynx <zlynx@acm.org>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Nick Piggin 2008-07-08 11:31:06 +02:00 committed by Martin Schwidefsky
parent 7b51ba38d9
commit 138c9021ca
1 changed files with 4 additions and 1 deletions
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5
include/asm-s390/pgtable.h
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@ -223,6 +223,9 @@ extern char empty_zero_page[PAGE_SIZE];
#define _PAGE_SPECIAL 0x004 /* SW associated with special page */
#define __HAVE_ARCH_PTE_SPECIAL
/* Set of bits not changed in pte_modify */
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_SPECIAL)
/* Six different types of pages. */
#define _PAGE_TYPE_EMPTY 0x400
#define _PAGE_TYPE_NONE 0x401
@ -681,7 +684,7 @@ static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *pt
*/
static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
{
pte_val(pte) &= PAGE_MASK;
pte_val(pte) &= _PAGE_CHG_MASK;
pte_val(pte) |= pgprot_val(newprot);
return pte;
}