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=-12.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 0FB67C2D0A3 for ; Tue, 3 Nov 2020 15:23:04 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 831EF20735 for ; Tue, 3 Nov 2020 15:23:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 831EF20735 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A58496B0078; Tue, 3 Nov 2020 10:22:54 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9B0A36B007B; Tue, 3 Nov 2020 10:22:54 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7BE4B6B007D; Tue, 3 Nov 2020 10:22:54 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0242.hostedemail.com [216.40.44.242]) by kanga.kvack.org (Postfix) with ESMTP id 3B8D66B0078 for ; Tue, 3 Nov 2020 10:22:54 -0500 (EST) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id D0B5D1EF1 for ; Tue, 3 Nov 2020 15:22:53 +0000 (UTC) X-FDA: 77443474626.27.boats63_200a195272b9 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin27.hostedemail.com (Postfix) with ESMTP id B56923D677 for ; Tue, 3 Nov 2020 15:22:51 +0000 (UTC) X-HE-Tag: boats63_200a195272b9 X-Filterd-Recvd-Size: 9029 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf41.hostedemail.com (Postfix) with ESMTP for ; Tue, 3 Nov 2020 15:22:51 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 30AADAE37; Tue, 3 Nov 2020 15:22:50 +0000 (UTC) From: Vlastimil Babka To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alexander Potapenko , Kees Cook , Michal Hocko , David Hildenbrand , Mateusz Nosek , Laura Abbott , Vlastimil Babka Subject: [PATCH v2 2/5] mm, page_poison: use static key more efficiently Date: Tue, 3 Nov 2020 16:22:34 +0100 Message-Id: <20201103152237.9853-3-vbabka@suse.cz> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201103152237.9853-1-vbabka@suse.cz> References: <20201103152237.9853-1-vbabka@suse.cz> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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: Commit 11c9c7edae06 ("mm/page_poison.c: replace bool variable with static= key") changed page_poisoning_enabled() to a static key check. However, the func= tion is not inlined, so each check still involves a function call with overhea= d not eliminated when page poisoning is disabled. Analogically to how debug_pagealloc is handled, this patch converts page_poisoning_enabled() back to boolean check, and introduces page_poisoning_enabled_static() for fast paths. Both functions are inline= d. The function kernel_poison_pages() is also called unconditionally and doe= s the static key check inside. Remove it from there and put it to callers. = Also split it to two functions kernel_poison_pages() and kernel_unpoison_pages= () instead of the confusing bool parameter. Also optimize the check that enables page poisoning instead of debug_page= alloc for architectures without proper debug_pagealloc support. Move the check = to init_mem_debugging_and_hardening() to enable a single static key instead = of having two static branches in page_poisoning_enabled_static(). Signed-off-by: Vlastimil Babka --- drivers/virtio/virtio_balloon.c | 2 +- include/linux/mm.h | 23 +++++++++++--- mm/page_alloc.c | 19 ++++++++++-- mm/page_poison.c | 53 +++++---------------------------- 4 files changed, 43 insertions(+), 54 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_ball= oon.c index 481611c09dae..e53faed6ba93 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -1116,7 +1116,7 @@ static int virtballoon_validate(struct virtio_devic= e *vdev) */ if (!want_init_on_free() && (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY) || - !page_poisoning_enabled())) + !page_poisoning_enabled_static())) __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_PAGE_POISON); else if (!virtio_has_feature(vdev, VIRTIO_BALLOON_F_PAGE_POISON)) __virtio_clear_bit(vdev, VIRTIO_BALLOON_F_REPORTING); diff --git a/include/linux/mm.h b/include/linux/mm.h index e0bc1c8aa2a6..4d6dd9f44571 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2867,12 +2867,27 @@ extern int apply_to_existing_page_range(struct mm= _struct *mm, =20 extern void init_mem_debugging_and_hardening(void); #ifdef CONFIG_PAGE_POISONING -extern bool page_poisoning_enabled(void); -extern void kernel_poison_pages(struct page *page, int numpages, int ena= ble); +extern void kernel_poison_pages(struct page *page, int numpages); +extern void kernel_unpoison_pages(struct page *page, int numpages); +extern bool _page_poisoning_enabled_early; +DECLARE_STATIC_KEY_FALSE(_page_poisoning_enabled); +static inline bool page_poisoning_enabled(void) +{ + return _page_poisoning_enabled_early; +} +/* + * For use in fast paths after init_mem_debugging() has run, or when a + * false negative result is not harmful when called too early. + */ +static inline bool page_poisoning_enabled_static(void) +{ + return (static_branch_unlikely(&_page_poisoning_enabled)); +} #else static inline bool page_poisoning_enabled(void) { return false; } -static inline void kernel_poison_pages(struct page *page, int numpages, - int enable) { } +static inline bool page_poisoning_enabled_static(void) { return false; } +static inline void kernel_poison_pages(struct page *page, int numpages) = { } +static inline void kernel_unpoison_pages(struct page *page, int numpages= ) { } #endif =20 DECLARE_STATIC_KEY_FALSE(init_on_alloc); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 44d596c9c764..fd7f9345adc0 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -775,6 +775,17 @@ void init_mem_debugging_and_hardening(void) static_branch_enable(&init_on_free); } =20 +#ifdef CONFIG_PAGE_POISONING + /* + * Page poisoning is debug page alloc for some arches. If + * either of those options are enabled, enable poisoning. + */ + if (page_poisoning_enabled() || + (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && + debug_pagealloc_enabled())) + static_branch_enable(&_page_poisoning_enabled); +#endif + #ifdef CONFIG_DEBUG_PAGEALLOC if (!debug_pagealloc_enabled()) return; @@ -1260,7 +1271,8 @@ static __always_inline bool free_pages_prepare(stru= ct page *page, if (want_init_on_free()) kernel_init_free_pages(page, 1 << order); =20 - kernel_poison_pages(page, 1 << order, 0); + if (page_poisoning_enabled_static()) + kernel_poison_pages(page, 1 << order); /* * arch_free_page() can make the page's contents inaccessible. s390 * does this. So nothing which can access the page's contents should @@ -2206,7 +2218,7 @@ static inline int check_new_page(struct page *page) static inline bool free_pages_prezeroed(void) { return (IS_ENABLED(CONFIG_PAGE_POISONING_ZERO) && - page_poisoning_enabled()) || want_init_on_free(); + page_poisoning_enabled_static()) || want_init_on_free(); } =20 #ifdef CONFIG_DEBUG_VM @@ -2269,7 +2281,8 @@ inline void post_alloc_hook(struct page *page, unsi= gned int order, if (debug_pagealloc_enabled_static()) kernel_map_pages(page, 1 << order, 1); kasan_alloc_pages(page, order); - kernel_poison_pages(page, 1 << order, 1); + if (page_poisoning_enabled_static()) + kernel_unpoison_pages(page, 1 << order); set_page_owner(page, order, gfp_flags); } =20 diff --git a/mm/page_poison.c b/mm/page_poison.c index ae0482cded87..dd7aeada036f 100644 --- a/mm/page_poison.c +++ b/mm/page_poison.c @@ -8,45 +8,17 @@ #include #include =20 -static DEFINE_STATIC_KEY_FALSE_RO(want_page_poisoning); +bool _page_poisoning_enabled_early; +EXPORT_SYMBOL(_page_poisoning_enabled_early); +DEFINE_STATIC_KEY_FALSE(_page_poisoning_enabled); +EXPORT_SYMBOL(_page_poisoning_enabled); =20 static int __init early_page_poison_param(char *buf) { - int ret; - bool tmp; - - ret =3D strtobool(buf, &tmp); - if (ret) - return ret; - - if (tmp) - static_branch_enable(&want_page_poisoning); - else - static_branch_disable(&want_page_poisoning); - - return 0; + return kstrtobool(buf, &_page_poisoning_enabled_early); } early_param("page_poison", early_page_poison_param); =20 -/** - * page_poisoning_enabled - check if page poisoning is enabled - * - * Return true if page poisoning is enabled, or false if not. - */ -bool page_poisoning_enabled(void) -{ - /* - * Assumes that debug_pagealloc_enabled is set before - * memblock_free_all. - * Page poisoning is debug page alloc for some arches. If - * either of those options are enabled, enable poisoning. - */ - return (static_branch_unlikely(&want_page_poisoning) || - (!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) && - debug_pagealloc_enabled())); -} -EXPORT_SYMBOL_GPL(page_poisoning_enabled); - static void poison_page(struct page *page) { void *addr =3D kmap_atomic(page); @@ -58,7 +30,7 @@ static void poison_page(struct page *page) kunmap_atomic(addr); } =20 -static void poison_pages(struct page *page, int n) +void kernel_poison_pages(struct page *page, int n) { int i; =20 @@ -117,7 +89,7 @@ static void unpoison_page(struct page *page) kunmap_atomic(addr); } =20 -static void unpoison_pages(struct page *page, int n) +void kernel_unpoison_pages(struct page *page, int n) { int i; =20 @@ -125,17 +97,6 @@ static void unpoison_pages(struct page *page, int n) unpoison_page(page + i); } =20 -void kernel_poison_pages(struct page *page, int numpages, int enable) -{ - if (!page_poisoning_enabled()) - return; - - if (enable) - unpoison_pages(page, numpages); - else - poison_pages(page, numpages); -} - #ifndef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC void __kernel_map_pages(struct page *page, int numpages, int enable) { --=20 2.29.1