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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B819C433EF for ; Wed, 15 Dec 2021 13:36:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237466AbhLONgZ (ORCPT ); Wed, 15 Dec 2021 08:36:25 -0500 Received: from foss.arm.com ([217.140.110.172]:52202 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234413AbhLONgX (ORCPT ); Wed, 15 Dec 2021 08:36:23 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5212811D4; Wed, 15 Dec 2021 05:36:22 -0800 (PST) Received: from FVFF77S0Q05N (unknown [10.57.67.176]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9A6A13F774; Wed, 15 Dec 2021 05:36:17 -0800 (PST) Date: Wed, 15 Dec 2021 13:36:14 +0000 From: Mark Rutland To: Alexander Potapenko Cc: Alexander Viro , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 10/43] kmsan: pgtable: reduce vmalloc space Message-ID: References: <20211214162050.660953-1-glider@google.com> <20211214162050.660953-11-glider@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211214162050.660953-11-glider@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Tue, Dec 14, 2021 at 05:20:17PM +0100, Alexander Potapenko wrote: > KMSAN is going to use 3/4 of existing vmalloc space to hold the > metadata, therefore we lower VMALLOC_END to make sure vmalloc() doesn't > allocate past the first 1/4. > > Signed-off-by: Alexander Potapenko It might be worth adding an 'x86: ' prefix to the commit title, since this specifically affects x86 headers. Mark. > --- > Link: https://linux-review.googlesource.com/id/I9d8b7f0a88a639f1263bc693cbd5c136626f7efd > --- > arch/x86/include/asm/pgtable_64_types.h | 41 ++++++++++++++++++++++++- > arch/x86/mm/init_64.c | 2 +- > 2 files changed, 41 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h > index 91ac106545703..7f15d43754a34 100644 > --- a/arch/x86/include/asm/pgtable_64_types.h > +++ b/arch/x86/include/asm/pgtable_64_types.h > @@ -139,7 +139,46 @@ extern unsigned int ptrs_per_p4d; > # define VMEMMAP_START __VMEMMAP_BASE_L4 > #endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */ > > -#define VMALLOC_END (VMALLOC_START + (VMALLOC_SIZE_TB << 40) - 1) > +#define VMEMORY_END (VMALLOC_START + (VMALLOC_SIZE_TB << 40) - 1) > + > +#ifndef CONFIG_KMSAN > +#define VMALLOC_END VMEMORY_END > +#else > +/* > + * In KMSAN builds vmalloc area is four times smaller, and the remaining 3/4 > + * are used to keep the metadata for virtual pages. The memory formerly > + * belonging to vmalloc area is now laid out as follows: > + * > + * 1st quarter: VMALLOC_START to VMALLOC_END - new vmalloc area > + * 2nd quarter: KMSAN_VMALLOC_SHADOW_START to > + * VMALLOC_END+KMSAN_VMALLOC_SHADOW_OFFSET - vmalloc area shadow > + * 3rd quarter: KMSAN_VMALLOC_ORIGIN_START to > + * VMALLOC_END+KMSAN_VMALLOC_ORIGIN_OFFSET - vmalloc area origins > + * 4th quarter: KMSAN_MODULES_SHADOW_START to KMSAN_MODULES_ORIGIN_START > + * - shadow for modules, > + * KMSAN_MODULES_ORIGIN_START to > + * KMSAN_MODULES_ORIGIN_START + MODULES_LEN - origins for modules. > + */ > +#define VMALLOC_QUARTER_SIZE ((VMALLOC_SIZE_TB << 40) >> 2) > +#define VMALLOC_END (VMALLOC_START + VMALLOC_QUARTER_SIZE - 1) > + > +/* > + * vmalloc metadata addresses are calculated by adding shadow/origin offsets > + * to vmalloc address. > + */ > +#define KMSAN_VMALLOC_SHADOW_OFFSET VMALLOC_QUARTER_SIZE > +#define KMSAN_VMALLOC_ORIGIN_OFFSET (VMALLOC_QUARTER_SIZE << 1) > + > +#define KMSAN_VMALLOC_SHADOW_START (VMALLOC_START + KMSAN_VMALLOC_SHADOW_OFFSET) > +#define KMSAN_VMALLOC_ORIGIN_START (VMALLOC_START + KMSAN_VMALLOC_ORIGIN_OFFSET) > + > +/* > + * The shadow/origin for modules are placed one by one in the last 1/4 of > + * vmalloc space. > + */ > +#define KMSAN_MODULES_SHADOW_START (VMALLOC_END + KMSAN_VMALLOC_ORIGIN_OFFSET + 1) > +#define KMSAN_MODULES_ORIGIN_START (KMSAN_MODULES_SHADOW_START + MODULES_LEN) > +#endif /* CONFIG_KMSAN */ > > #define MODULES_VADDR (__START_KERNEL_map + KERNEL_IMAGE_SIZE) > /* The module sections ends with the start of the fixmap */ > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index 36098226a9573..8e884e44a8d1e 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1287,7 +1287,7 @@ static void __init preallocate_vmalloc_pages(void) > unsigned long addr; > const char *lvl; > > - for (addr = VMALLOC_START; addr <= VMALLOC_END; addr = ALIGN(addr + 1, PGDIR_SIZE)) { > + for (addr = VMALLOC_START; addr <= VMEMORY_END; addr = ALIGN(addr + 1, PGDIR_SIZE)) { > pgd_t *pgd = pgd_offset_k(addr); > p4d_t *p4d; > pud_t *pud; > -- > 2.34.1.173.g76aa8bc2d0-goog >