Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752191AbaKOJnh (ORCPT ); Sat, 15 Nov 2014 04:43:37 -0500 Received: from mail-ie0-f169.google.com ([209.85.223.169]:45378 "EHLO mail-ie0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751329AbaKOJne (ORCPT ); Sat, 15 Nov 2014 04:43:34 -0500 MIME-Version: 1.0 In-Reply-To: References: <20141114204517.GA24402@www.outflux.net> Date: Sat, 15 Nov 2014 01:43:32 -0800 X-Google-Sender-Auth: 518ZfpGJdyEa30eq_I2RdgXEBb8 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: multipart/mixed; boundary=001a113f924e26a7be0507e2942a Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --001a113f924e26a7be0507e2942a Content-Type: text/plain; charset=UTF-8 On Fri, Nov 14, 2014 at 7:38 PM, Yinghai Lu wrote: > On Fri, Nov 14, 2014 at 6:46 PM, Kees Cook wrote: >> 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 ? Please check attached one that clean up the highmap tail... Subject: [RFC PATCH] x86, 64bit: cleanup highmap tail near partial 2M range 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 mem. and is not wasted. 3. add cleanup_highmap_tail for [_brk_end, pm_end). Kernel Layout: [ 0.000000] .text: [0x01000000-0x0200d5c8] [ 0.000000] .rodata: [0x02200000-0x02a1cfff] [ 0.000000] .data: [0x02c00000-0x02e50e7f] [ 0.000000] .init: [0x02e52000-0x03212fff] [ 0.000000] .bss: [0x03221000-0x0437bfff] [ 0.000000] .brk: [0x0437c000-0x043a1fff] Actually used brk: [ 0.272959] memblock_reserve: [0x0000000437c000-0x00000004382fff] flags 0x0 BRK Before patch: ---[ High Kernel Mapping ]--- 0xffffffff80000000-0xffffffff81000000 16M pmd 0xffffffff81000000-0xffffffff82200000 18M ro PSE GLB x pmd 0xffffffff82200000-0xffffffff82c00000 10M ro PSE GLB NX pmd 0xffffffff82c00000-0xffffffff82e00000 2M RW PSE GLB NX pmd 0xffffffff82e00000-0xffffffff83000000 2M RW GLB NX pte 0xffffffff83000000-0xffffffff83200000 2M RW PSE GLB NX pmd 0xffffffff83200000-0xffffffff83400000 2M RW GLB NX pte 0xffffffff83400000-0xffffffff84200000 14M RW PSE GLB NX pmd 0xffffffff84200000-0xffffffff843a2000 1672K RW GLB NX pte 0xffffffff843a2000-0xffffffff84400000 376K RW GLB x pte 0xffffffff84400000-0xffffffffa0000000 444M pmd After patch: ---[ High Kernel Mapping ]--- 0xffffffff80000000-0xffffffff81000000 16M pmd 0xffffffff81000000-0xffffffff82200000 18M ro PSE GLB x pmd 0xffffffff82200000-0xffffffff82c00000 10M ro PSE GLB NX pmd 0xffffffff82c00000-0xffffffff82e00000 2M RW PSE GLB NX pmd 0xffffffff82e00000-0xffffffff83000000 2M RW GLB NX pte 0xffffffff83000000-0xffffffff83200000 2M RW PSE GLB NX pmd 0xffffffff83200000-0xffffffff83400000 2M RW GLB NX pte 0xffffffff83400000-0xffffffff84200000 14M RW PSE GLB NX pmd 0xffffffff84200000-0xffffffff84383000 1548K RW GLB NX pte 0xffffffff84383000-0xffffffff84400000 500K pte 0xffffffff84400000-0xffffffffa0000000 444M pmd Signed-off-by: Yinghai Lu --- arch/x86/mm/init_64.c | 23 ++++++++++++++++++++++- arch/x86/mm/pageattr.c | 2 +- 2 files changed, 23 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 @@ -375,6 +375,7 @@ void __init init_extra_mapping_uc(unsign __init_extra_mapping(phys, size, PAGE_KERNEL_LARGE_NOCACHE); } +static pmd_t *last_pmd; /* * The head.S code sets up the kernel high mapping: * @@ -408,9 +409,26 @@ void __init cleanup_highmap(void) continue; if (vaddr < (unsigned long) _text || vaddr > end) set_pmd(pmd, __pmd(0)); + else + last_pmd = pmd; } } +static void __init cleanup_highmap_tail(unsigned long addr) +{ + int i; + pte_t *pte; + + if (!last_pmd || pmd_none(*last_pmd)) + return; + + pte = (pte_t *)pmd_page_vaddr(*last_pmd); + pte += pte_index(addr); + + for (i = pte_index(addr); i < PTRS_PER_PTE; i++, pte++) + set_pte(pte, __pte(0)); +} + static unsigned long __meminit phys_pte_init(pte_t *pte_page, unsigned long addr, unsigned long end, pgprot_t prot) @@ -1124,7 +1142,8 @@ 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); @@ -1137,6 +1156,8 @@ void mark_rodata_ro(void) * should also be not-executable. */ set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT); + if (all_end < pmd_end) + cleanup_highmap_tail(all_end); rodata_test(); Index: linux-2.6/arch/x86/mm/pageattr.c =================================================================== --- linux-2.6.orig/arch/x86/mm/pageattr.c +++ linux-2.6/arch/x86/mm/pageattr.c @@ -100,7 +100,7 @@ static inline unsigned long highmap_star static inline unsigned long highmap_end_pfn(void) { - return __pa_symbol(roundup(_brk_end, PMD_SIZE)) >> PAGE_SHIFT; + return __pa_symbol(PFN_ALIGN(_brk_end)) >> PAGE_SHIFT; } #endif 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