Messages in this thread Patch in this message | | | Subject | [BUGFIX] x86_64: NX bit handling in change_page_attr | From | "Huang, Ying" <> | Date | Fri, 17 Aug 2007 13:28:38 +0800 |
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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>
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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; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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