Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935441AbaKODiV (ORCPT ); Fri, 14 Nov 2014 22:38:21 -0500 Received: from mail-ig0-f170.google.com ([209.85.213.170]:51388 "EHLO mail-ig0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934378AbaKODiU (ORCPT ); Fri, 14 Nov 2014 22:38:20 -0500 MIME-Version: 1.0 In-Reply-To: References: <20141114204517.GA24402@www.outflux.net> Date: Fri, 14 Nov 2014 19:38:19 -0800 X-Google-Sender-Auth: z0li8uOt6ndm6KuSE_uraRoBYH8 Message-ID: Subject: Re: [PATCH v2] x86, mm: set NX across entire PMD at boot From: Yinghai Lu To: Kees Cook Cc: Linux Kernel Mailing List , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , "the arch/x86 maintainers" , Andrew Morton , Andy Lutomirski , Yasuaki Ishimatsu , Wang Nan , David Vrabel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 14, 2014 at 6:46 PM, Kees Cook wrote: > On Fri, Nov 14, 2014 at 6:29 PM, Yinghai Lu wrote: >> should use attached one instead. >> >> 1. should use _brk_end instead of &end, as we only use partial of >> brk. >> 2. [_brk_end, pm_end) page range is already converted. aka >> is not wasted. > > Are you sure? For me, _brk_end isn't far enough: > > [ 1.475572] all_end: 0xffffffff82df5000 > [ 1.476736] _brk_end: 0xffffffff82dd6000 Yes. _brk_end should be small then &_end. > >> >> --- >> arch/x86/mm/init_64.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> Index: linux-2.6/arch/x86/mm/init_64.c >> =================================================================== >> --- linux-2.6.orig/arch/x86/mm/init_64.c >> +++ linux-2.6/arch/x86/mm/init_64.c >> @@ -1124,7 +1124,8 @@ void mark_rodata_ro(void) >> unsigned long end = (unsigned long) &__end_rodata_hpage_align; >> unsigned long text_end = PFN_ALIGN(&__stop___ex_table); >> unsigned long rodata_end = PFN_ALIGN(&__end_rodata); >> - unsigned long all_end = PFN_ALIGN(&_end); >> + unsigned long all_end = PFN_ALIGN(_brk_end); >> + unsigned long pmd_end = roundup(all_end, PMD_SIZE); >> >> printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n", >> (end - start) >> 10); >> @@ -1136,7 +1137,7 @@ void mark_rodata_ro(void) >> * The rodata/data/bss/brk section (but not the kernel text!) >> * should also be not-executable. >> */ >> - set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT); >> + set_memory_nx(rodata_start, (pmd_end - rodata_start) >> PAGE_SHIFT); >> >> rodata_test(); >> >> @@ -1148,6 +1149,7 @@ void mark_rodata_ro(void) >> set_memory_ro(start, (end-start) >> PAGE_SHIFT); >> #endif >> >> + /* all_end to pmd_end is handled via free_all_bootmem() */ >> free_init_pages("unused kernel", >> (unsigned long) __va(__pa_symbol(text_end)), >> (unsigned long) __va(__pa_symbol(rodata_start))); > > This patch produces the same results as my v1 patch: > > 0xffffffff8202d000-0xffffffff82200000 1868K RW GLB NX pte > 0xffffffff82200000-0xffffffff82e00000 12M RW PSE GLB NX pmd > 0xffffffff82e00000-0xffffffffc0000000 978M pmd > > Is this correct? It sounded like tglx wanted the pmd split, like this: > > 0xffffffff82200000-0xffffffff82c00000 10M RW PSE GLB NX pmd > 0xffffffff82c00000-0xffffffff82df5000 2004K RW GLB NX pte > 0xffffffff82df5000-0xffffffff82e00000 44K RW NX pte > 0xffffffff82e00000-0xffffffffc0000000 978M pmd Need to remove GLB ? Yinghai -- 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/