From patchwork Thu Dec 30 19:14:53 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: 12701624 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 3988AC433F5 for ; Thu, 30 Dec 2021 19:15:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 36D4B6B00AD; Thu, 30 Dec 2021 14:15:48 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3449B6B00AF; Thu, 30 Dec 2021 14:15:48 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 199646B00B0; Thu, 30 Dec 2021 14:15:48 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0082.hostedemail.com [216.40.44.82]) by kanga.kvack.org (Postfix) with ESMTP id 049756B00AD for ; Thu, 30 Dec 2021 14:15:48 -0500 (EST) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id C55BA181AC550 for ; Thu, 30 Dec 2021 19:15:47 +0000 (UTC) X-FDA: 78975415134.11.21FB330 Received: from out2.migadu.com (out2.migadu.com [188.165.223.204]) by imf19.hostedemail.com (Postfix) with ESMTP id 116481A0005 for ; Thu, 30 Dec 2021 19:15:46 +0000 (UTC) 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=1640891746; 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=vAwQcHTlCiYChpYnlNq+QkugFDzxho9e0I/gAsV+YMU=; b=AQgDkQD0wIPFHfk3DwCfbzvuGQd5Tr/0yV8e+3KFE+t7PuAACZ43LPLyOAnrZnyF+l71je qZRLSHQifFHmU0iCvBFaSARbvhGoAGJzgthAHBGcsoMk0I0wMH00RozL53SOj9/MgduT/d /YXyai/y9Ydgn/e3TI7uXi5KcnS65Zo= From: andrey.konovalov@linux.dev To: Andrew Morton Cc: Andrey Konovalov , Marco Elver , Alexander Potapenko , 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 v5 28/39] kasan, page_alloc: allow skipping unpoisoning for HW_TAGS Date: Thu, 30 Dec 2021 20:14:53 +0100 Message-Id: In-Reply-To: References: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT X-Migadu-Auth-User: linux.dev Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=AQgDkQD0; spf=pass (imf19.hostedemail.com: domain of andrey.konovalov@linux.dev designates 188.165.223.204 as permitted sender) smtp.mailfrom=andrey.konovalov@linux.dev; dmarc=pass (policy=none) header.from=linux.dev X-Rspamd-Queue-Id: 116481A0005 X-Stat-Signature: sgfmz5ar63ktkjjbajk3qah1fhfx4npb X-Rspamd-Server: rspam04 X-HE-Tag: 1640891746-288813 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: 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 v4->v5: - Cosmetic changes to __def_gfpflag_names_kasan and __GFP_BITS_SHIFT. 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 | 21 +++++++++++++-------- include/trace/events/mmflags.h | 5 +++-- mm/page_alloc.c | 31 ++++++++++++++++++++++--------- 3 files changed, 38 insertions(+), 19 deletions(-) diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 9dce456d147a..487126f089e1 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 @@ -237,22 +239,25 @@ struct vm_area_struct; * intended for optimization: setting memory tags at the same time as zeroing * memory has minimal additional performace impact. * - * %__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) + \ +#define __GFP_BITS_SHIFT (24 + \ + 2 * 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..5ffc7bdce91f 100644 --- a/include/trace/events/mmflags.h +++ b/include/trace/events/mmflags.h @@ -51,8 +51,9 @@ {(unsigned long)__GFP_ZEROTAGS, "__GFP_ZEROTAGS"} \ #ifdef CONFIG_KASAN_HW_TAGS -#define __def_gfpflag_names_kasan \ - , {(unsigned long)__GFP_SKIP_KASAN_POISON, "__GFP_SKIP_KASAN_POISON"} +#define __def_gfpflag_names_kasan , \ + {(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 a07f9e9b0abc..102f0cd8815e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2395,6 +2395,26 @@ 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) { @@ -2434,15 +2454,8 @@ 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. */