Messages in this thread | | | Date | Tue, 11 Sep 2007 20:23:32 -0700 | From | Andrew Morton <> | Subject | Re: [BUGFIX] x86_64: NX bit handling in change_page_attr |
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On Fri, 17 Aug 2007 13:28:38 +0800 "Huang, Ying" <ying.huang@intel.com> wrote:
> This patch fixes a bug of change_page_attr/change_page_attr_addr on > Intel x86_64 CPU. After changing page attribute to be executable with > these functions, the page remains un-executable on Intel x86_64 > CPU. Because on Intel x86_64 CPU, only if the "NX" bits of all four > level page tables are cleared, the corresponding page is executable > (refer to section 4.13.2 of Intel 64 and IA-32 Architectures Software > Developer's Manual). So, the bug is fixed through clearing the "NX" > bit of PMD when splitting the huge PMD. > > Signed-off-by: Huang Ying <ying.huang@intel.com> > > --- > > Index: linux-2.6.23-rc2-mm2/arch/x86_64/mm/pageattr.c > =================================================================== > --- linux-2.6.23-rc2-mm2.orig/arch/x86_64/mm/pageattr.c 2007-08-17 12:50:25.000000000 +0800 > +++ linux-2.6.23-rc2-mm2/arch/x86_64/mm/pageattr.c 2007-08-17 12:50:48.000000000 +0800 > @@ -147,6 +147,7 @@ > split = split_large_page(address, prot, ref_prot2); > if (!split) > return -ENOMEM; > + pgprot_val(ref_prot2) &= ~_PAGE_NX; > set_pte(kpte, mk_pte(split, ref_prot2)); > kpte_page = split; > }
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