From: Huang, Ying Date: Wed, 17 Oct 2007 16:04:35 +0000 (+0200) Subject: x86: NX bit handling in change_page_attr() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=84e0fdb1754d066dd0a8b257de7299f392d1e727;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git x86: NX bit handling in change_page_attr() This patch fixes a bug of change_page_attr/change_page_attr_addr on Intel x86_64 CPUs. 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 Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/mm/pageattr_64.c b/arch/x86/mm/pageattr_64.c index 10b9809ce821..93d795d7c2ae 100644 --- a/arch/x86/mm/pageattr_64.c +++ b/arch/x86/mm/pageattr_64.c @@ -148,6 +148,7 @@ __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot, 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; }