From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B2714C2D0CD for ; Wed, 18 Dec 2019 09:24:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8918821582 for ; Wed, 18 Dec 2019 09:24:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726734AbfLRJYp (ORCPT ); Wed, 18 Dec 2019 04:24:45 -0500 Received: from mx2.suse.de ([195.135.220.15]:60562 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725799AbfLRJYo (ORCPT ); Wed, 18 Dec 2019 04:24:44 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 93C0CAB71; Wed, 18 Dec 2019 09:24:41 +0000 (UTC) Subject: Re: [RFC PATCH 1/3] x86/xen: add basic KASAN support for PV kernel To: Sergey Dyasli , xen-devel@lists.xen.org, kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org Cc: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Boris Ostrovsky , Stefano Stabellini , George Dunlap , Ross Lagerwall References: <20191217140804.27364-1-sergey.dyasli@citrix.com> <20191217140804.27364-2-sergey.dyasli@citrix.com> From: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Message-ID: <934a2950-9079-138d-5476-5eabd84dfec5@suse.com> Date: Wed, 18 Dec 2019 10:24:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: <20191217140804.27364-2-sergey.dyasli@citrix.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17.12.19 15:08, Sergey Dyasli wrote: > This enables to use Outline instrumentation for Xen PV kernels. > > KASAN_INLINE and KASAN_VMALLOC options currently lead to boot crashes > and hence disabled. > > Rough edges in the patch are marked with XXX. > > Signed-off-by: Sergey Dyasli > --- > arch/x86/mm/init.c | 14 ++++++++++++++ > arch/x86/mm/kasan_init_64.c | 28 ++++++++++++++++++++++++++++ > arch/x86/xen/Makefile | 7 +++++++ > arch/x86/xen/enlighten_pv.c | 3 +++ > arch/x86/xen/mmu_pv.c | 13 +++++++++++-- > arch/x86/xen/multicalls.c | 10 ++++++++++ > drivers/xen/Makefile | 2 ++ > kernel/Makefile | 2 ++ > lib/Kconfig.kasan | 3 ++- > 9 files changed, 79 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c > index e7bb483557c9..0c98a45eec6c 100644 > --- a/arch/x86/mm/init.c > +++ b/arch/x86/mm/init.c > @@ -8,6 +8,8 @@ > #include > #include > > +#include > + > #include > #include > #include > @@ -835,6 +837,18 @@ void free_kernel_image_pages(const char *what, void *begin, void *end) > unsigned long end_ul = (unsigned long)end; > unsigned long len_pages = (end_ul - begin_ul) >> PAGE_SHIFT; > > + /* > + * XXX: skip this for now. Otherwise it leads to: > + * > + * (XEN) mm.c:2713:d157v0 Bad type (saw 8c00000000000001 != exp e000000000000000) for mfn 36f40 (pfn 02f40) > + * (XEN) mm.c:1043:d157v0 Could not get page type PGT_writable_page > + * (XEN) mm.c:1096:d157v0 Error getting mfn 36f40 (pfn 02f40) from L1 entry 8010000036f40067 for l1e_owner d157, pg_owner d157 > + * > + * and further #PF error: [PROT] [WRITE] in the kernel. > + */ > + if (xen_pv_domain() && IS_ENABLED(CONFIG_KASAN)) > + return; > + I guess this is related to freeing some kasan page tables without unpinning them? > free_init_pages(what, begin_ul, end_ul); > > /* > diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c > index cf5bc37c90ac..caee2022f8b0 100644 > --- a/arch/x86/mm/kasan_init_64.c > +++ b/arch/x86/mm/kasan_init_64.c > @@ -13,6 +13,8 @@ > #include > #include > > +#include > + > #include > #include > #include > @@ -20,6 +22,9 @@ > #include > #include > > +#include > +#include > + > extern struct range pfn_mapped[E820_MAX_ENTRIES]; > > static p4d_t tmp_p4d_table[MAX_PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE); > @@ -305,6 +310,12 @@ static struct notifier_block kasan_die_notifier = { > }; > #endif > > +#ifdef CONFIG_XEN > +/* XXX: this should go to some header */ > +void __init set_page_prot(void *addr, pgprot_t prot); > +void __init pin_pagetable_pfn(unsigned cmd, unsigned long pfn); > +#endif > + Instead of exporting those, why don't you ... > void __init kasan_early_init(void) > { > int i; > @@ -332,6 +343,16 @@ void __init kasan_early_init(void) > for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++) > kasan_early_shadow_p4d[i] = __p4d(p4d_val); > > + if (xen_pv_domain()) { > + /* PV page tables must have PAGE_KERNEL_RO */ > + set_page_prot(kasan_early_shadow_pud, PAGE_KERNEL_RO); > + set_page_prot(kasan_early_shadow_pmd, PAGE_KERNEL_RO); > + set_page_prot(kasan_early_shadow_pte, PAGE_KERNEL_RO); add a function doing that to mmu_pv.c (e.g. xen_pv_kasan_early_init())? > + > + /* Add mappings to the initial PV page tables */ > + kasan_map_early_shadow((pgd_t *)xen_start_info->pt_base); > + } > + > kasan_map_early_shadow(early_top_pgt); > kasan_map_early_shadow(init_top_pgt); > } > @@ -369,6 +390,13 @@ void __init kasan_init(void) > __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE)); > } > > + if (xen_pv_domain()) { > + /* PV page tables must be pinned */ > + set_page_prot(early_top_pgt, PAGE_KERNEL_RO); > + pin_pagetable_pfn(MMUEXT_PIN_L4_TABLE, > + PFN_DOWN(__pa_symbol(early_top_pgt))); and another one like xen_pv_kasan_init() here. > + } > + > load_cr3(early_top_pgt); > __flush_tlb_all(); > > diff --git a/arch/x86/xen/Makefile b/arch/x86/xen/Makefile > index 084de77a109e..102fad0b0bca 100644 > --- a/arch/x86/xen/Makefile > +++ b/arch/x86/xen/Makefile > @@ -1,3 +1,10 @@ > +KASAN_SANITIZE_enlighten_pv.o := n > +KASAN_SANITIZE_enlighten.o := n > +KASAN_SANITIZE_irq.o := n > +KASAN_SANITIZE_mmu_pv.o := n > +KASAN_SANITIZE_p2m.o := n > +KASAN_SANITIZE_multicalls.o := n > + > # SPDX-License-Identifier: GPL-2.0 > OBJECT_FILES_NON_STANDARD_xen-asm_$(BITS).o := y > > diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c > index ae4a41ca19f6..27de55699f24 100644 > --- a/arch/x86/xen/enlighten_pv.c > +++ b/arch/x86/xen/enlighten_pv.c > @@ -72,6 +72,7 @@ > #include > #include > #include > +#include > > #ifdef CONFIG_ACPI > #include > @@ -1231,6 +1232,8 @@ asmlinkage __visible void __init xen_start_kernel(void) > /* Get mfn list */ > xen_build_dynamic_phys_to_machine(); > > + kasan_early_init(); > + > /* > * Set up kernel GDT and segment registers, mainly so that > * -fstack-protector code can be executed. > diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c > index c8dbee62ec2a..eaf63f1f26af 100644 > --- a/arch/x86/xen/mmu_pv.c > +++ b/arch/x86/xen/mmu_pv.c > @@ -1079,7 +1079,7 @@ static void xen_exit_mmap(struct mm_struct *mm) > > static void xen_post_allocator_init(void); > > -static void __init pin_pagetable_pfn(unsigned cmd, unsigned long pfn) > +void __init pin_pagetable_pfn(unsigned cmd, unsigned long pfn) > { > struct mmuext_op op; > > @@ -1767,7 +1767,7 @@ static void __init set_page_prot_flags(void *addr, pgprot_t prot, > if (HYPERVISOR_update_va_mapping((unsigned long)addr, pte, flags)) > BUG(); > } > -static void __init set_page_prot(void *addr, pgprot_t prot) > +void __init set_page_prot(void *addr, pgprot_t prot) > { > return set_page_prot_flags(addr, prot, UVMF_NONE); > } > @@ -1943,6 +1943,15 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn) > if (i && i < pgd_index(__START_KERNEL_map)) > init_top_pgt[i] = ((pgd_t *)xen_start_info->pt_base)[i]; > > +#ifdef CONFIG_KASAN > + /* > + * Copy KASAN mappings > + * ffffec0000000000 - fffffbffffffffff (=44 bits) kasan shadow memory (16TB) > + */ > + for (i = 0xec0 >> 3; i < 0xfc0 >> 3; i++) > + init_top_pgt[i] = ((pgd_t *)xen_start_info->pt_base)[i]; > +#endif > + > /* Make pagetable pieces RO */ > set_page_prot(init_top_pgt, PAGE_KERNEL_RO); > set_page_prot(level3_ident_pgt, PAGE_KERNEL_RO); > diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c > index 07054572297f..5e4729efbbe2 100644 > --- a/arch/x86/xen/multicalls.c > +++ b/arch/x86/xen/multicalls.c > @@ -99,6 +99,15 @@ void xen_mc_flush(void) > ret++; > } > > + /* > + * XXX: Kasan produces quite a lot (~2000) of warnings in a form of: > + * > + * (XEN) mm.c:3222:d155v0 mfn 3704b already pinned > + * > + * during kasan_init(). They are benign, but silence them for now. > + * Otherwise, booting takes too long due to printk() spam. > + */ > +#ifndef CONFIG_KASAN It might be interesting to identify the problematic page tables. I guess this would require some hacking to avoid the multicalls in order to identify which page table should not be pinned again. Juergen