Commit-ID: e16d8a6cbb499c5c8bfe9330d3351b649bded4af Gitweb: http://git.kernel.org/tip/e16d8a6cbb499c5c8bfe9330d3351b649bded4af Author: Andy Lutomirski <l...@kernel.org> AuthorDate: Tue, 26 Apr 2016 08:52:44 -0700 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Tue, 26 Apr 2016 19:52:57 +0200
Revert "x86/mm/32: Set NX in __supported_pte_mask before enabling paging" 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-and-tested-by: Meelis Roos <mr...@linux.ee> Signed-off-by: Andy Lutomirski <l...@kernel.org> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Borislav Petkov <b...@alien8.de> Cc: Brian Gerst <brge...@gmail.com> Cc: Denys Vlasenko <dvlas...@redhat.com> Cc: H. Peter Anvin <h...@zytor.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Mike Galbraith <efa...@gmx.de> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/59bd15f7f4b56b633a611b7f70876c6d2ad01a98.1461685884.git.l...@kernel.org Signed-off-by: Ingo Molnar <mi...@kernel.org> --- 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 54cdbd2..af11129 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 8bea847..f65a33f 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; }
