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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 E2794C432BE for ; Tue, 31 Aug 2021 08:40:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C8FD661029 for ; Tue, 31 Aug 2021 08:40:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240412AbhHaIlE (ORCPT ); Tue, 31 Aug 2021 04:41:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:48672 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240403AbhHaIlD (ORCPT ); Tue, 31 Aug 2021 04:41:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 243F960E98; Tue, 31 Aug 2021 08:40:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1630399208; bh=gqiAk6efM2NN49iQ6niUDVype6wdTyTtrakguXN3l0s=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=G+2OqoixJR5gxsUHm+HCT4jEjATdneaHH8fhceORBhplLmZnEa8lBaX3OdTjQtbUj ypyZHT7vKvuDgO6ss0PxUhJXTLgWgyquyyn9/4Wrl7+R//GUcG4mQ7Igkhg9YNm7i+ HljCOvfeS2INezlaD3Xblc9SWH4FWctfVr0SubaJAav7J2VZ860G0YYhtnNlPQo/lJ 7xouBtHZyh9x53cP1oIT2tkFmU/5oR6Njp3bv8dtOQ6YDIpU+nSCUUfphv5mZU2Fa1 gQcm92SwWyqLwAh8tTDAqlam2nc+VuC95/Wuj295yfSmdaeRAiR2LEHdiLoyiRlIgc 7q3OxLc8rIjIQ== Date: Tue, 31 Aug 2021 11:40:01 +0300 From: Mike Rapoport To: Rick Edgecombe Cc: dave.hansen@intel.com, luto@kernel.org, peterz@infradead.org, x86@kernel.org, akpm@linux-foundation.org, keescook@chromium.org, shakeelb@google.com, vbabka@suse.cz, linux-mm@kvack.org, linux-hardening@vger.kernel.org, kernel-hardening@lists.openwall.com, ira.weiny@intel.com, dan.j.williams@intel.com, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH v2 05/19] x86, mm: Use cache of page tables Message-ID: References: <20210830235927.6443-1-rick.p.edgecombe@intel.com> <20210830235927.6443-6-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210830235927.6443-6-rick.p.edgecombe@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Mon, Aug 30, 2021 at 04:59:13PM -0700, Rick Edgecombe wrote: > Change the page table allocation functions defined in pgalloc.h to use > a cache of physically grouped pages. This will let the page tables be set > with PKS permissions later. > > For userspace page tables, they are gathered up using mmu gather, and > freed along with other types of pages in swap.c. Move setting/clearing of > the PageTable page flag to the allocators so that swap can know to return > this page to the cache of page tables, and not free it to the page > allocator. Where it currently is, in the ctor/dtors, causes it to be > cleared before the page gets to swap. > > Do not set PKS permissions on the page tables, because the page table > setting functions cannot handle it yet. This will be done in later > patches. > > Signed-off-by: Rick Edgecombe > --- > arch/x86/include/asm/pgalloc.h | 6 ++- > arch/x86/include/asm/pgtable.h | 6 +++ > arch/x86/mm/pgtable.c | 79 ++++++++++++++++++++++++++++++++++ > include/asm-generic/pgalloc.h | 44 ++++++++++++++----- > include/linux/mm.h | 11 +++-- > mm/swap.c | 6 +++ > mm/swap_state.c | 5 +++ > 7 files changed, 142 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h > index c7ec5bb88334..1ff308ea76cd 100644 > --- a/arch/x86/include/asm/pgalloc.h > +++ b/arch/x86/include/asm/pgalloc.h > @@ -7,6 +7,10 @@ > #include > > #define __HAVE_ARCH_PTE_ALLOC_ONE > +#ifdef CONFIG_PKS_PG_TABLES > +#define __HAVE_ARCH_FREE_TABLE > +#define __HAVE_ARCH_ALLOC_TABLE I think one define would suffice. If we'd ever have an architecture that can implement only one of those, we update the ifdefery in asm-generic/pgalloc.h > +#endif > #define __HAVE_ARCH_PGD_FREE > #include > > @@ -162,7 +166,7 @@ static inline void p4d_free(struct mm_struct *mm, p4d_t *p4d) > return; > > BUG_ON((unsigned long)p4d & (PAGE_SIZE-1)); > - free_page((unsigned long)p4d); > + free_table(virt_to_page(p4d)); > } > > extern void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d); ... > diff --git a/include/asm-generic/pgalloc.h b/include/asm-generic/pgalloc.h > index 02932efad3ab..e576c19abc8c 100644 > --- a/include/asm-generic/pgalloc.h > +++ b/include/asm-generic/pgalloc.h > @@ -2,11 +2,26 @@ > #ifndef __ASM_GENERIC_PGALLOC_H > #define __ASM_GENERIC_PGALLOC_H > > +#include > + Why is this required? > #ifdef CONFIG_MMU > > #define GFP_PGTABLE_KERNEL (GFP_KERNEL | __GFP_ZERO) > #define GFP_PGTABLE_USER (GFP_PGTABLE_KERNEL | __GFP_ACCOUNT) > > +#ifndef __HAVE_ARCH_ALLOC_TABLE > +static inline struct page *alloc_table(gfp_t gfp) > +{ > + return alloc_page(gfp); > +} > +#else /* __HAVE_ARCH_ALLOC_TABLE */ > +extern struct page *alloc_table(gfp_t gfp); > +#endif /* __HAVE_ARCH_ALLOC_TABLE */ > + > +#ifdef __HAVE_ARCH_FREE_TABLE > +extern void free_table(struct page *); > +#endif /* __HAVE_ARCH_FREE_TABLE */ > + > /** > * __pte_alloc_one_kernel - allocate a page for PTE-level kernel page table > * @mm: the mm_struct of the current context ... > diff --git a/include/linux/mm.h b/include/linux/mm.h > index c13c7af7cad3..ab63d5a201cb 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -2327,6 +2327,13 @@ static inline bool ptlock_init(struct page *page) { return true; } > static inline void ptlock_free(struct page *page) {} > #endif /* USE_SPLIT_PTE_PTLOCKS */ > > +#ifndef CONFIG_PKS_PG_TABLES > +static inline void free_table(struct page *table_page) > +{ > + __free_pages(table_page, 0); > +} > +#endif /* CONFIG_PKS_PG_TABLES */ > + Can't this live in asm-generic/pgalloc.h? Then you won't need to include linux/mm.h there. > static inline void pgtable_init(void) > { > ptlock_cache_init(); > @@ -2337,7 +2344,6 @@ static inline bool pgtable_pte_page_ctor(struct page *page) > { > if (!ptlock_init(page)) > return false; > - __SetPageTable(page); This change is only valid when __HAVE_ARCH_ALLOC_TABLE is set. > inc_lruvec_page_state(page, NR_PAGETABLE); > return true; > } > @@ -2345,7 +2351,6 @@ static inline bool pgtable_pte_page_ctor(struct page *page) > static inline void pgtable_pte_page_dtor(struct page *page) > { > ptlock_free(page); > - __ClearPageTable(page); > dec_lruvec_page_state(page, NR_PAGETABLE); > } > -- Sincerely yours, Mike.