| From | Andi Kleen <> | Subject | [PATCH] [29/31] CPA: Add a BUG_ON checking for someone setting the kernel text NX | Date | Mon, 14 Jan 2008 23:17:02 +0100 (CET) |
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Someone setting NX on the kernel text tends to result in nasty failures and triple faults, so BUG_ON early for that.
Does not cover __inittext.
Signed-off-by: Andi Kleen <ak@suse.de>
--- arch/x86/mm/pageattr_32.c | 8 ++++++++ 1 file changed, 8 insertions(+)
Index: linux/arch/x86/mm/pageattr_32.c =================================================================== --- linux.orig/arch/x86/mm/pageattr_32.c +++ linux/arch/x86/mm/pageattr_32.c @@ -242,6 +242,14 @@ __change_page_attr(struct page *page, pg BUG_ON(PageLRU(kpte_page)); BUG_ON(PageCompound(kpte_page)); + /* + * Better fail early if someone sets the kernel text to NX. + * Does not cover __inittext + */ + BUG_ON(address >= (unsigned long)&_text && + address < (unsigned long)&_etext && + (pgprot_val(prot) & _PAGE_NX)); + set_tlb_flush(address, cache_attr_changed(*kpte, prot, level), level < 3);
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