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=-16.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 ADB1EC43460 for ; Fri, 16 Apr 2021 23:07:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 36ECF610CD for ; Fri, 16 Apr 2021 23:07:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 36ECF610CD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C8D4A6B006E; Fri, 16 Apr 2021 19:07:54 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id C64746B0070; Fri, 16 Apr 2021 19:07:54 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B04B26B0071; Fri, 16 Apr 2021 19:07:54 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0083.hostedemail.com [216.40.44.83]) by kanga.kvack.org (Postfix) with ESMTP id 930026B006E for ; Fri, 16 Apr 2021 19:07:54 -0400 (EDT) Received: from smtpin38.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 5519812CA for ; Fri, 16 Apr 2021 23:07:54 +0000 (UTC) X-FDA: 78039769668.38.E0721EB Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf05.hostedemail.com (Postfix) with ESMTP id 4BB55E000114 for ; Fri, 16 Apr 2021 23:07:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=tfA9/CMMjzVJbfa5k3nU3g5wOaQhTGv4Y2DdGMdqE7Q=; b=sTOSCTMeSHNrr2R6hLTjOnMirn /l111sXXa+hkgheaR3XHlrEYp9dRyu1Hx8aLdl7v/0IpOQHkQIeiAwc7DnALGgsfq1OfrOHRpSTWO SYlZOacvnN9dQNE9YhagejFjJKq3xQKyWtSOPbovu7laaFnuJSs6yA3l8k88k+5LfIDyBsGCKy7um vF5omj4LN2RyRJXB6KRFFzh/OdYT/oj1ZLEfFu9KqMqY1JcBqzP8ZhrETltLNmZvDtTz/WlHs3SMZ 6KuL/e0wM16OjO/w9S7tttTFE1ATb7HFLwJ8ZeoYI0HagCJy/8znvaOXSqeZQgTAoUqdG6HDHOzRs 28cEctHw==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lXXYg-00AZOD-UA; Fri, 16 Apr 2021 23:07:32 +0000 From: "Matthew Wilcox (Oracle)" To: brouer@redhat.com Cc: "Matthew Wilcox (Oracle)" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, ilias.apalodimas@linaro.org, mcroce@linux.microsoft.com, grygorii.strashko@ti.com, arnd@kernel.org, hch@lst.de, linux-snps-arc@lists.infradead.org, mhocko@kernel.org, mgorman@suse.de Subject: [PATCH 1/2] mm: Fix struct page layout on 32-bit systems Date: Sat, 17 Apr 2021 00:07:23 +0100 Message-Id: <20210416230724.2519198-2-willy@infradead.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210416230724.2519198-1-willy@infradead.org> References: <20210416230724.2519198-1-willy@infradead.org> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 4BB55E000114 X-Stat-Signature: mrxcc3bswatserb3tbsb74tfbb164b35 Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf05; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618614473-281765 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: 32-bit architectures which expect 8-byte alignment for 8-byte integers and need 64-bit DMA addresses (arc, arm, mips, ppc) had their struct page inadvertently expanded in 2019. When the dma_addr_t was added, it forced the alignment of the union to 8 bytes, which inserted a 4 byte gap between 'flags' and the union. Fix this by storing the dma_addr_t in one or two adjacent unsigned longs. This restores the alignment to that of an unsigned long, and also fixes a potential problem where (on a big endian platform), the bit used to denot= e PageTail could inadvertently get set, and a racing get_user_pages_fast() could dereference a bogus compound_head(). Fixes: c25fff7171be ("mm: add dma_addr_t to struct page") Signed-off-by: Matthew Wilcox (Oracle) --- include/linux/mm_types.h | 4 ++-- include/net/page_pool.h | 12 +++++++++++- net/core/page_pool.c | 12 +++++++----- 3 files changed, 20 insertions(+), 8 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 6613b26a8894..5aacc1c10a45 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -97,10 +97,10 @@ struct page { }; struct { /* page_pool used by netstack */ /** - * @dma_addr: might require a 64-bit value even on + * @dma_addr: might require a 64-bit value on * 32-bit architectures. */ - dma_addr_t dma_addr; + unsigned long dma_addr[2]; }; struct { /* slab, slob and slub */ union { diff --git a/include/net/page_pool.h b/include/net/page_pool.h index b5b195305346..db7c7020746a 100644 --- a/include/net/page_pool.h +++ b/include/net/page_pool.h @@ -198,7 +198,17 @@ static inline void page_pool_recycle_direct(struct p= age_pool *pool, =20 static inline dma_addr_t page_pool_get_dma_addr(struct page *page) { - return page->dma_addr; + dma_addr_t ret =3D page->dma_addr[0]; + if (sizeof(dma_addr_t) > sizeof(unsigned long)) + ret |=3D (dma_addr_t)page->dma_addr[1] << 32; + return ret; +} + +static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t = addr) +{ + page->dma_addr[0] =3D addr; + if (sizeof(dma_addr_t) > sizeof(unsigned long)) + page->dma_addr[1] =3D addr >> 32; } =20 static inline bool is_page_pool_compiled_in(void) diff --git a/net/core/page_pool.c b/net/core/page_pool.c index ad8b0707af04..f014fd8c19a6 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -174,8 +174,10 @@ static void page_pool_dma_sync_for_device(struct pag= e_pool *pool, struct page *page, unsigned int dma_sync_size) { + dma_addr_t dma_addr =3D page_pool_get_dma_addr(page); + dma_sync_size =3D min(dma_sync_size, pool->p.max_len); - dma_sync_single_range_for_device(pool->p.dev, page->dma_addr, + dma_sync_single_range_for_device(pool->p.dev, dma_addr, pool->p.offset, dma_sync_size, pool->p.dma_dir); } @@ -226,7 +228,7 @@ static struct page *__page_pool_alloc_pages_slow(stru= ct page_pool *pool, put_page(page); return NULL; } - page->dma_addr =3D dma; + page_pool_set_dma_addr(page, dma); =20 if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) page_pool_dma_sync_for_device(pool, page, pool->p.max_len); @@ -294,13 +296,13 @@ void page_pool_release_page(struct page_pool *pool,= struct page *page) */ goto skip_dma_unmap; =20 - dma =3D page->dma_addr; + dma =3D page_pool_get_dma_addr(page); =20 - /* When page is unmapped, it cannot be returned our pool */ + /* When page is unmapped, it cannot be returned to our pool */ dma_unmap_page_attrs(pool->p.dev, dma, PAGE_SIZE << pool->p.order, pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC); - page->dma_addr =3D 0; + page_pool_set_dma_addr(page, 0); skip_dma_unmap: /* This may be the last page returned, releasing the pool, so * it is not safe to reference pool afterwards. --=20 2.30.2