From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757992AbbGGXRY (ORCPT ); Tue, 7 Jul 2015 19:17:24 -0400 Received: from mail-ig0-f175.google.com ([209.85.213.175]:34755 "EHLO mail-ig0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752614AbbGGXRQ (ORCPT ); Tue, 7 Jul 2015 19:17:16 -0400 MIME-Version: 1.0 In-Reply-To: <1436300428-21163-41-git-send-email-yinghai@kernel.org> References: <1436300428-21163-1-git-send-email-yinghai@kernel.org> <1436300428-21163-41-git-send-email-yinghai@kernel.org> Date: Tue, 7 Jul 2015 16:17:15 -0700 X-Google-Sender-Auth: lvSBFYXcoYfZw-aF1aftQs8Rwyk Message-ID: Subject: Re: [PATCH 40/42] x86, 64bit: remove highmap for not needed ranges From: Kees Cook To: Yinghai Lu Cc: "H. Peter Anvin" , Baoquan He , LKML 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 Tue, Jul 7, 2015 at 1:20 PM, Yinghai Lu wrote: > add cleanup_highmap_late to remove highmap for initmem, around rodata, and > [_brk_end, all_end). > > Kernel Layout: > > [ 0.000000] .text: [0x01000000-0x0200df88] > [ 0.000000] .rodata: [0x02200000-0x02a1dfff] > [ 0.000000] .data: [0x02c00000-0x02e510ff] > [ 0.000000] .init: [0x02e53000-0x03213fff] > [ 0.000000] .bss: [0x03222000-0x0437cfff] > [ 0.000000] .brk: [0x0437d000-0x043a2fff] > > Actually used brk: > [ 0.270365] memblock_reserve: [0x0000000437d000-0x00000004383fff] flags 0x0 BRK > > Before patch: > ---[ High Kernel Mapping ]--- > 0xffffffff80000000-0xffffffff81000000 16M pmd > 0xffffffff81000000-0xffffffff82000000 16M ro PSE GLB x pmd > 0xffffffff82000000-0xffffffff82011000 68K ro GLB x pte > 0xffffffff82011000-0xffffffff82200000 1980K RW GLB x pte What change introduced this RW + x area? I don't see any of those currently in my page tables. -Kees > 0xffffffff82200000-0xffffffff82a00000 8M ro PSE GLB NX pmd > 0xffffffff82a00000-0xffffffff82a1e000 120K ro GLB NX pte > 0xffffffff82a1e000-0xffffffff82c00000 1928K RW GLB NX pte > 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 > 0xffffffff83400000-0xffffffff84400000 16M RW PSE GLB NX pmd > 0xffffffff84400000-0xffffffffa0000000 444M pmd > > After patch: > ---[ High Kernel Mapping ]--- > 0xffffffff80000000-0xffffffff81000000 16M pmd > 0xffffffff81000000-0xffffffff82000000 16M ro PSE GLB x pmd > 0xffffffff82000000-0xffffffff82012000 72K ro GLB x pte > 0xffffffff82012000-0xffffffff82200000 1976K pte > 0xffffffff82200000-0xffffffff82a00000 8M ro PSE GLB NX pmd > 0xffffffff82a00000-0xffffffff82a1e000 120K ro GLB NX pte > 0xffffffff82a1e000-0xffffffff82c00000 1928K pte > 0xffffffff82c00000-0xffffffff82e00000 2M RW PSE GLB NX pmd > 0xffffffff82e00000-0xffffffff82e53000 332K RW GLB NX pte > 0xffffffff82e53000-0xffffffff83000000 1716K pte > 0xffffffff83000000-0xffffffff83200000 2M pmd > 0xffffffff83200000-0xffffffff83214000 80K pte > 0xffffffff83214000-0xffffffff83400000 1968K RW GLB NX pte > 0xffffffff83400000-0xffffffff84200000 14M RW PSE GLB NX pmd > 0xffffffff84200000-0xffffffff84384000 1552K RW GLB NX pte > 0xffffffff84384000-0xffffffff84400000 496K pte > 0xffffffff84400000-0xffffffffa0000000 444M pmd > > So remove some range around rodata. > > -v4: adapt it to all_end change. > > Signed-off-by: Yinghai Lu > --- > arch/x86/mm/init_64.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 62 insertions(+) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 2507b98..38aa59c 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1010,6 +1010,61 @@ void __init mem_init(void) > } > > #ifdef CONFIG_DEBUG_RODATA > +static void remove_highmap_2m(unsigned long addr) > +{ > + pgd_t *pgd = pgd_offset_k(addr); > + pud_t *pud = (pud_t *)pgd_page_vaddr(*pgd) + pud_index(addr); > + pmd_t *pmd = (pmd_t *)pud_page_vaddr(*pud) + pmd_index(addr); > + > + set_pmd(pmd, __pmd(0)); > +} > + > +static void remove_highmap_2m_partial(unsigned long addr, unsigned long end) > +{ > + int i; > + pgd_t *pgd = pgd_offset_k(addr); > + pud_t *pud = (pud_t *)pgd_page_vaddr(*pgd) + pud_index(addr); > + pmd_t *pmd = (pmd_t *)pud_page_vaddr(*pud) + pmd_index(addr); > + pte_t *pte = (pte_t *)pmd_page_vaddr(*pmd) + pte_index(addr); > + > + for (i = pte_index(addr); i < pte_index(end - 1) + 1; i++, pte++) > + set_pte(pte, __pte(0)); > +} > + > +static void cleanup_highmap_late(unsigned long start, unsigned long end) > +{ > + unsigned long addr; > + unsigned long start_2m_aligned = roundup(start, PMD_SIZE); > + unsigned long end_2m_aligned = rounddown(end, PMD_SIZE); > + > + start = PFN_ALIGN(start); > + end &= PAGE_MASK; > + > + if (start >= end) > + return; > + > + if (start < start_2m_aligned) { > + unsigned long tmp = min(start_2m_aligned, end); > + > + set_memory_4k(start, (tmp - start) >> PAGE_SHIFT); > + remove_highmap_2m_partial(start, tmp); > + } > + > + for (addr = start_2m_aligned; addr < end_2m_aligned; addr += PMD_SIZE) > + remove_highmap_2m(addr); > + > + if (start <= end_2m_aligned && end_2m_aligned < end) { > + set_memory_4k(end_2m_aligned, > + (end - end_2m_aligned) >> PAGE_SHIFT); > + remove_highmap_2m_partial(end_2m_aligned, end); > + } > + > + subtract_range(pfn_highmapped, NR_RANGE, > + __pa_symbol(start) >> PAGE_SHIFT, > + __pa_symbol(end) >> PAGE_SHIFT); > + nr_pfn_highmapped = clean_sort_range(pfn_highmapped, NR_RANGE); > +} > + > const int rodata_test_data = 0xC3; > EXPORT_SYMBOL_GPL(rodata_test_data); > > @@ -1058,6 +1113,7 @@ 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 data_start = PFN_ALIGN(&_sdata); > unsigned long all_end; > > printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n", > @@ -1081,6 +1137,12 @@ void mark_rodata_ro(void) > all_end = roundup(_brk_end, PMD_SIZE); > set_memory_nx(rodata_start, (all_end - rodata_start) >> PAGE_SHIFT); > > + cleanup_highmap_late(text_end, rodata_start); > + cleanup_highmap_late(rodata_end, data_start); > + cleanup_highmap_late(PFN_ALIGN(_brk_end), all_end); > + cleanup_highmap_late((unsigned long)(&__init_begin), > + (unsigned long)(&__init_end)); > + > rodata_test(); > > #ifdef CONFIG_CPA_DEBUG > -- > 1.8.4.5 > > -- > 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/ -- Kees Cook Chrome OS Security