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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2A309C433F5 for ; Sun, 29 May 2022 17:04:29 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4249C8D0002; Sun, 29 May 2022 13:04:28 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3D0148D0001; Sun, 29 May 2022 13:04:28 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 299148D0002; Sun, 29 May 2022 13:04:28 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 173608D0001 for ; Sun, 29 May 2022 13:04:28 -0400 (EDT) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id C101934C4F for ; Sun, 29 May 2022 17:04:27 +0000 (UTC) X-FDA: 79519404174.15.A3B84F0 Received: from sipsolutions.net (s3.sipsolutions.net [144.76.43.62]) by imf30.hostedemail.com (Postfix) with ESMTP id CD7788004B for ; Sun, 29 May 2022 17:03:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=BLA4aQRvfntqLMm99a+1xZPVRcOluvd10rffKGFrc10=; t=1653843866; x=1655053466; b=kvXRV08vKAdinCcRCptBT9wbsUjo3U7jIQuSAKn/dma5Bmu KU86mDx/IKu+U10wvHVZTwKfw5kXgs1/Z8XWg+RnyiEtWUMm19pvuM0+anH7Ww2YaqgglvEcK0Lg/ ceaHe+aMsVif09fMKwQ49He0dNa6MwmXn79uUeZBzNqNgRAUnK0sG2+dCPqF2BOiinwC0vTvedocC BlH6g6wCMrfqE5xgBRpEyLfgZlm4tw/weKxEDasLvklIIYRaYFjp0HQrYq+pNGn3yylm1HoGy7rH0 6GreqbJSngFBUlKBHnpjShKdhVe91c7ys9KqzqlPVvq5V4uBxabjrKQOcz4EtHNA==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.95) (envelope-from ) id 1nvMKn-007myT-UG; Sun, 29 May 2022 19:04:10 +0200 Message-ID: <1a4e51a4d2ed51e7ae1ff55bd4da6a47fad7c0bf.camel@sipsolutions.net> Subject: Re: [PATCH v2 2/2] UML: add support for KASAN under x86_64 From: Johannes Berg To: David Gow , Vincent Whitchurch , Patricia Alfonso , Jeff Dike , Richard Weinberger , anton.ivanov@cambridgegreys.com, Dmitry Vyukov , Brendan Higgins , Andrew Morton , Andrey Konovalov , Andrey Ryabinin Cc: kasan-dev , linux-um@lists.infradead.org, LKML , Daniel Latypov , linux-mm@kvack.org Date: Sun, 29 May 2022 19:04:08 +0200 In-Reply-To: <20220527185600.1236769-2-davidgow@google.com> References: <20220527185600.1236769-1-davidgow@google.com> <20220527185600.1236769-2-davidgow@google.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.1 (3.44.1-1.fc36) MIME-Version: 1.0 X-malware-bazaar: not-scanned Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=sipsolutions.net header.s=mail header.b=kvXRV08v; dmarc=pass (policy=none) header.from=sipsolutions.net; spf=pass (imf30.hostedemail.com: domain of johannes@sipsolutions.net designates 144.76.43.62 as permitted sender) smtp.mailfrom=johannes@sipsolutions.net X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: CD7788004B X-Stat-Signature: 1szt7g4cnnw6dpe8ypfxn69z86jof6q1 X-HE-Tag: 1653843834-324148 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 2022-05-27 at 11:56 -0700, David Gow wrote: >=20 > The UML-specific KASAN initializer uses mmap to map the roughly 2.25TB You say 2.25TB here, and =20 > +config KASAN_SHADOW_OFFSET > + hex > + depends on KASAN > + default 0x100000000000 > + help > + This is the offset at which the ~2.25TB of shadow memory is here too, of course. But I notice that I get ~16TB address space use when running, > +/* used in kasan_mem_to_shadow to divide by 8 */ > +#define KASAN_SHADOW_SCALE_SHIFT 3 > + > +#ifdef CONFIG_X86_64 > +#define KASAN_HOST_USER_SPACE_END_ADDR 0x00007fffffffffffUL > +/* KASAN_SHADOW_SIZE is the size of total address space divided by 8 */ > +#define KASAN_SHADOW_SIZE ((KASAN_HOST_USER_SPACE_END_ADDR + 1) >> \ > + KASAN_SHADOW_SCALE_SHIFT) because this ends up being 0x100000000000, i.e. 16 TiB. Is that intentional? Was something missed? Maybe KASAN_HOST_USER_SPACE_END_ADDR was too big? It doesn't really matter, but I guess then the documentation should be updated. johannes