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Commit 138c9021 authored by Nick Piggin's avatar Nick Piggin Committed by Martin Schwidefsky
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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: default avatarRyan Hope <rmh3093@gmail.com>
Debugged-by: default avatarZan Lynx <zlynx@acm.org>
Acked-by: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarNick Piggin <npiggin@suse.de>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 7b51ba38

include/asm-s390/pgtable.h

+4 −1
Original line number Diff line number Diff line
@@ -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;

}