From 51fc41a90603eaee7b6d03b6027be8f22fcf8ef9 Mon Sep 17 00:00:00 2001 From: Max Filippov Date: Sat, 18 May 2013 23:34:30 +0400 Subject: [PATCH] xtensa: fix fast_store_prohibited _PAGE_WRITABLE_BIT test Before _PAGE_WRITABLE_BIT test fast_store_prohibited must make sure that PTE is present. Otherwise 'writable' bit is undefined and may be reused in the 'file offset' or 'swap type' PTE fields. Signed-off-by: Max Filippov Signed-off-by: Chris Zankel --- arch/xtensa/kernel/entry.S | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S index 5082507..fa94512 100644 --- a/arch/xtensa/kernel/entry.S +++ b/arch/xtensa/kernel/entry.S @@ -1792,10 +1792,15 @@ ENTRY(fast_store_prohibited) l32i a0, a0, 0 beqz a0, 2f - /* Note that we assume _PAGE_WRITABLE_BIT is only set if pte is valid.*/ + /* + * Note that we test _PAGE_WRITABLE_BIT only if PTE is present + * and is not PAGE_NONE. See pgtable.h for possible PTE layouts. + */ _PTE_OFFSET(a0, a1, a4) l32i a4, a0, 0 # read pteval + movi a1, _PAGE_CA_INVALID + ball a4, a1, 2f bbci.l a4, _PAGE_WRITABLE_BIT, 2f movi a1, _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_HW_WRITE -- 2.7.4