From patchwork Mon Dec 20 22:02:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: andrey.konovalov@linux.dev X-Patchwork-Id: 12696933 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1BEC7C433EF for ; Mon, 20 Dec 2021 22:18:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=TiTdZF7C7FvkQoRcIH3nsFQMlFdbQaHucdKrMWuyDdU=; b=GZ3TMjwxmeSTUx 9OpDbuo5CcB6KdaHUkAU42cob9eTdkt4eLx9uFaL4pGicdjU3++EALEa3uJ7Vq61crDuKKqzjldOX Et9tJ5zAdyqKb0AdyDs5L3CLUVrBnpG23INeIEVJ7aC0Y2qVNqhejtQhFRnBrQVDrd7w7qFCQ0mwg I7kTy1aw6z0Nql3qFkpZbqGcFuNPWUf+jq4yNIw5JXW7WDfQ4JEw1rfwUjAIc+OOO61nyTryqLZhG nWJ3y52vk26Z/3XS8+RdLNoFkfSa8dbM+a2mUcS9jPvqyWyfb+hexSwsXLre32SICXDb6shdg6T+i 0s8K7CE3Z8aMeP2v6aqQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mzQxe-004kC5-8q; Mon, 20 Dec 2021 22:16:50 +0000 Received: from out1.migadu.com ([2001:41d0:2:863f::]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mzQje-004cfq-Hq for linux-arm-kernel@lists.infradead.org; Mon, 20 Dec 2021 22:02:25 +0000 X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1640037741; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lgqujwoixk5/zdATKZ/Zn/56oW8wMB5cacRc9FCqpKE=; b=rFvsj83qvlbqtnuRslEGkNMxCXpK6/Wk4mOvgxwDEBvTWwHXuSCgP2AUcQyYhHY6NZuj+Y GJZWhfHGEHMfRy99YqWj06nWtgcgUzbPToO8Ll1AN2K8+yzbAnhgKCJ3KvHkMpWj/awiYZ zTTiqbgM4k5qGeb4LP1XYjmViU1Hpb0= From: andrey.konovalov@linux.dev To: Marco Elver , Alexander Potapenko , Andrew Morton Cc: Andrey Konovalov , Dmitry Vyukov , Andrey Ryabinin , kasan-dev@googlegroups.com, linux-mm@kvack.org, Vincenzo Frascino , Catalin Marinas , Will Deacon , Mark Rutland , linux-arm-kernel@lists.infradead.org, Peter Collingbourne , Evgenii Stepanov , linux-kernel@vger.kernel.org, Andrey Konovalov Subject: [PATCH mm v4 28/39] kasan, page_alloc: allow skipping unpoisoning for HW_TAGS Date: Mon, 20 Dec 2021 23:02:00 +0100 Message-Id: <73a0b47ec72a9c29e0efc18a9941237b3b3ad736.1640036051.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211220_140222_989909_8FBB7124 X-CRM114-Status: GOOD ( 17.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Andrey Konovalov Add a new GFP flag __GFP_SKIP_KASAN_UNPOISON that allows skipping KASAN poisoning for page_alloc allocations. The flag is only effective with HW_TAGS KASAN. This flag will be used by vmalloc code for page_alloc allocations backing vmalloc() mappings in a following patch. The reason to skip KASAN poisoning for these pages in page_alloc is because vmalloc code will be poisoning them instead. Also reword the comment for __GFP_SKIP_KASAN_POISON. Signed-off-by: Andrey Konovalov --- Changes v3->v4: - Only define __GFP_SKIP_KASAN_POISON when CONFIG_KASAN_HW_TAGS is enabled. Changes v2->v3: - Update patch description. Signed-off-by: Andrey Konovalov --- include/linux/gfp.h | 18 ++++++++++++------ include/trace/events/mmflags.h | 4 +++- mm/page_alloc.c | 31 ++++++++++++++++++++++--------- 3 files changed, 37 insertions(+), 16 deletions(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 22709fcc4d3a..600f0749c3f2 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -55,12 +55,14 @@ struct vm_area_struct; #define ___GFP_ACCOUNT 0x400000u #define ___GFP_ZEROTAGS 0x800000u #ifdef CONFIG_KASAN_HW_TAGS -#define ___GFP_SKIP_KASAN_POISON 0x1000000u +#define ___GFP_SKIP_KASAN_UNPOISON 0x1000000u +#define ___GFP_SKIP_KASAN_POISON 0x2000000u #else +#define ___GFP_SKIP_KASAN_UNPOISON 0 #define ___GFP_SKIP_KASAN_POISON 0 #endif #ifdef CONFIG_LOCKDEP -#define ___GFP_NOLOCKDEP 0x2000000u +#define ___GFP_NOLOCKDEP 0x4000000u #else #define ___GFP_NOLOCKDEP 0 #endif @@ -235,21 +237,25 @@ struct vm_area_struct; * %__GFP_ZEROTAGS zeroes memory tags at allocation time if the memory itself * is being zeroed (either via __GFP_ZERO or via init_on_alloc). * - * %__GFP_SKIP_KASAN_POISON returns a page which does not need to be poisoned - * on deallocation. Typically used for userspace pages. Currently only has an - * effect in HW tags mode. + * %__GFP_SKIP_KASAN_UNPOISON makes KASAN skip unpoisoning on page allocation. + * Only effective in HW_TAGS mode. + * + * %__GFP_SKIP_KASAN_POISON makes KASAN skip poisoning on page deallocation. + * Typically, used for userspace pages. Only effective in HW_TAGS mode. */ #define __GFP_NOWARN ((__force gfp_t)___GFP_NOWARN) #define __GFP_COMP ((__force gfp_t)___GFP_COMP) #define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) #define __GFP_ZEROTAGS ((__force gfp_t)___GFP_ZEROTAGS) -#define __GFP_SKIP_KASAN_POISON ((__force gfp_t)___GFP_SKIP_KASAN_POISON) +#define __GFP_SKIP_KASAN_UNPOISON ((__force gfp_t)___GFP_SKIP_KASAN_UNPOISON) +#define __GFP_SKIP_KASAN_POISON ((__force gfp_t)___GFP_SKIP_KASAN_POISON) /* Disable lockdep for GFP context tracking */ #define __GFP_NOLOCKDEP ((__force gfp_t)___GFP_NOLOCKDEP) /* Room for N __GFP_FOO bits */ #define __GFP_BITS_SHIFT (24 + \ + IS_ENABLED(CONFIG_KASAN_HW_TAGS) + \ IS_ENABLED(CONFIG_KASAN_HW_TAGS) + \ IS_ENABLED(CONFIG_LOCKDEP)) #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1)) diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h index 414bf4367283..1329d9c4df56 100644 --- a/include/trace/events/mmflags.h +++ b/include/trace/events/mmflags.h @@ -52,7 +52,9 @@ #ifdef CONFIG_KASAN_HW_TAGS #define __def_gfpflag_names_kasan \ - , {(unsigned long)__GFP_SKIP_KASAN_POISON, "__GFP_SKIP_KASAN_POISON"} + , {(unsigned long)__GFP_SKIP_KASAN_POISON, "__GFP_SKIP_KASAN_POISON"} \ + , {(unsigned long)__GFP_SKIP_KASAN_UNPOISON, \ + "__GFP_SKIP_KASAN_UNPOISON"} #else #define __def_gfpflag_names_kasan #endif diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2ef0f531e881..2076b5cc7e2c 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2394,6 +2394,26 @@ static bool check_new_pages(struct page *page, unsigned int order) return false; } +static inline bool should_skip_kasan_unpoison(gfp_t flags, bool init_tags) +{ + /* Don't skip if a software KASAN mode is enabled. */ + if (IS_ENABLED(CONFIG_KASAN_GENERIC) || + IS_ENABLED(CONFIG_KASAN_SW_TAGS)) + return false; + + /* Skip, if hardware tag-based KASAN is not enabled. */ + if (!kasan_hw_tags_enabled()) + return true; + + /* + * With hardware tag-based KASAN enabled, skip if either: + * + * 1. Memory tags have already been cleared via tag_clear_highpage(). + * 2. Skipping has been requested via __GFP_SKIP_KASAN_UNPOISON. + */ + return init_tags || (flags & __GFP_SKIP_KASAN_UNPOISON); +} + inline void post_alloc_hook(struct page *page, unsigned int order, gfp_t gfp_flags) { @@ -2433,15 +2453,8 @@ inline void post_alloc_hook(struct page *page, unsigned int order, /* Note that memory is already initialized by the loop above. */ init = false; } - /* - * If either a software KASAN mode is enabled, or, - * in the case of hardware tag-based KASAN, - * if memory tags have not been cleared via tag_clear_highpage(). - */ - if (IS_ENABLED(CONFIG_KASAN_GENERIC) || - IS_ENABLED(CONFIG_KASAN_SW_TAGS) || - kasan_hw_tags_enabled() && !init_tags) { - /* Mark shadow memory or set memory tags. */ + if (!should_skip_kasan_unpoison(gfp_flags, init_tags)) { + /* Unpoison shadow memory or set memory tags. */ kasan_unpoison_pages(page, order, init); /* Note that memory is already initialized by KASAN. */