This reverts commit 320d25b6a05f8b73c23fc21025d2906ecdd2d4fc. This change was problematic for a couple of reasons:
1. It missed a some entry points (Xen things and 64-bit native). 2. The entry it changed can be executed more than once. This isn't really a problem, but it conflated per-cpu state setup and global state setup. 3. It broke 64-bit non-NX. 64-bit non-NX worked the other way around from 32-bit -- __supported_pte_mask had NX set initially and was *cleared* in x86_configure_nx. With the patch applied, it never got cleared. Reported-by: Meelis Roos <[email protected]> Signed-off-by: Andy Lutomirski <[email protected]> --- arch/x86/kernel/head_32.S | 6 ------ arch/x86/mm/setup_nx.c | 5 +++-- 2 files changed, 3 insertions(+), 8 deletions(-) diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 54cdbd2003fe..af1112980dd4 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -389,12 +389,6 @@ default_entry: /* Make changes effective */ wrmsr - /* - * And make sure that all the mappings we set up have NX set from - * the beginning. - */ - orl $(1 << (_PAGE_BIT_NX - 32)), pa(__supported_pte_mask + 4) - enable_paging: /* diff --git a/arch/x86/mm/setup_nx.c b/arch/x86/mm/setup_nx.c index 8bea84724a7d..f65a33f505b6 100644 --- a/arch/x86/mm/setup_nx.c +++ b/arch/x86/mm/setup_nx.c @@ -32,8 +32,9 @@ early_param("noexec", noexec_setup); void x86_configure_nx(void) { - /* If disable_nx is set, clear NX on all new mappings going forward. */ - if (disable_nx) + if (boot_cpu_has(X86_FEATURE_NX) && !disable_nx) + __supported_pte_mask |= _PAGE_NX; + else __supported_pte_mask &= ~_PAGE_NX; } -- 2.5.5
