From patchwork Wed Oct 21 08:56:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 11848793 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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 A4F4DC4363A for ; Wed, 21 Oct 2020 09:00:58 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0E31022453 for ; Wed, 21 Oct 2020 09:00:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="TWioFOXA"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="UPG0GcaS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0E31022453 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=a4qA2xPX6TOu8KiIpnyh4M5wQbgzKB1Xag9nWxO3qSk=; b=TWioFOXAHfEusKUHZDagA3e8k nup6fvpPVWbcBJPqR1itZ9n+U/q6GAtW5CQR1ImYgf/ezm+EkwtLIXjjkvU/ru3diClibvjt1Fzgo 2pcMjSzeqZIfeN2E0ekmsrFJgDy4AU4LvjL0Lmg8aNrHePNypiHQrJF4i16TFshWzJ+H/Z8H1zWRM 4jLnUuKW7aXVZyFVZ/V8YjaTDkma8zIpsfRBR+IdufbgPXPcpF0jb6dj1rRjJL0/mtw7t3B5S7IFI JC5FzFYEdBbVpfRmDEwD6HwXGdpDqTDqOa1AGYTXYThOAqc3XZYGwUkZZdDCB5Q+KEj+ssT53R5HQ SYBnJ8faQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kV9xS-0001pB-Ta; Wed, 21 Oct 2020 08:58:58 +0000 Received: from mail-wr1-x443.google.com ([2a00:1450:4864:20::443]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kV9vm-0001AG-7y for linux-arm-kernel@lists.infradead.org; Wed, 21 Oct 2020 08:57:21 +0000 Received: by mail-wr1-x443.google.com with SMTP id s9so2074928wro.8 for ; Wed, 21 Oct 2020 01:57:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=hPBU4fd0tsYMcwp3ePz/Ho5qxuZVtGOvHiVJ9lQm7jY=; b=UPG0GcaSTYJzjNnzuql1oJmuf2ORiGcXQtqBG64S8CJ+9ZNvyS7CG072HrAMR+73AB jB8MJNaRilWsUd4vS9zDKwBxbBP/BpyY0v72COGfai/Je6t+7CKMe5spgkDoEsWn64wK NHlOVjp/UNJrgmhaKbuEgaJ1CW341WCoy+fng= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=hPBU4fd0tsYMcwp3ePz/Ho5qxuZVtGOvHiVJ9lQm7jY=; b=rbbPtA82KHGYkOc/k6LpHNMou5NzUcqO05ajHdgUwiOPoRVLVBiJqtcAmZjYozcD5K G6VY2RuO93uYczSZsU9Jx7C2/udhGKisrXHuvw7+Z5wIfea+ntTsl8M9x+nJYZcWiFP8 EeWB5eTa+jPRCMHJ0G1trLc+q+++U7XC4bjm9LILvmF9XwRMmHkNQgxPagd8CCCrgorz Ar9CKcu2NGZylweREABPdERCXDygY6Q2qmhdYHdw9hu0KMhBw09231PQRfCzAH8G/CQ0 +5tX8GqSqvDlIpNjA1MvuaLTj0tOQsisPPi64o4DS1kT4Sb60xjBf+HhVENZWIdWBkd3 XF4A== X-Gm-Message-State: AOAM5332q3LsbpLIu4KBX6lCEqZPkhRI/dqXeubb8SjGOkc78l118IlD qhXcLa/rb4gHji9T/gRAQCFnyw== X-Google-Smtp-Source: ABdhPJxiUy0VPgMwBx+Gtgt9KHB4VMhTjzmZk29+O/BmQINbhNhalI0SnUGt8xo9L8gxRohjGILhBg== X-Received: by 2002:a5d:5009:: with SMTP id e9mr3539097wrt.104.1603270632595; Wed, 21 Oct 2020 01:57:12 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id q8sm2675939wro.32.2020.10.21.01.57.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Oct 2020 01:57:11 -0700 (PDT) From: Daniel Vetter To: DRI Development , LKML Subject: [PATCH v3 07/16] mm: Close race in generic_access_phys Date: Wed, 21 Oct 2020 10:56:46 +0200 Message-Id: <20201021085655.1192025-8-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201021085655.1192025-1-daniel.vetter@ffwll.ch> References: <20201021085655.1192025-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201021_045714_525266_4B3B1789 X-CRM114-Status: GOOD ( 22.63 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, linux-samsung-soc@vger.kernel.org, Jan Kara , Kees Cook , kvm@vger.kernel.org, Jason Gunthorpe , Dave Airlie , Daniel Vetter , Daniel Vetter , linux-mm@kvack.org, =?utf-8?b?SsOp?= =?utf-8?b?csO0bWUgR2xpc3Nl?= , John Hubbard , Benjamin Herrensmidt , Daniel Vetter , Dan Williams , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Way back it was a reasonable assumptions that iomem mappings never change the pfn range they point at. But this has changed: - gpu drivers dynamically manage their memory nowadays, invalidating ptes with unmap_mapping_range when buffers get moved - contiguous dma allocations have moved from dedicated carvetouts to cma regions. This means if we miss the unmap the pfn might contain pagecache or anon memory (well anything allocated with GFP_MOVEABLE) - even /dev/mem now invalidates mappings when the kernel requests that iomem region when CONFIG_IO_STRICT_DEVMEM is set, see 3234ac664a87 ("/dev/mem: Revoke mappings when a driver claims the region") Accessing pfns obtained from ptes without holding all the locks is therefore no longer a good idea. Fix this. Since ioremap might need to manipulate pagetables too we need to drop the pt lock and have a retry loop if we raced. While at it, also add kerneldoc and improve the comment for the vma_ops->access function. It's for accessing, not for moving the memory from iomem to system memory, as the old comment seemed to suggest. References: 28b2ee20c7cb ("access_process_vm device memory infrastructure") Signed-off-by: Daniel Vetter Cc: Jason Gunthorpe Cc: Dan Williams Cc: Kees Cook Cc: Benjamin Herrensmidt Cc: Dave Airlie Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: Dan Williams Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Signed-off-by: Daniel Vetter --- v2: Fix inversion in the retry check (John). --- include/linux/mm.h | 3 ++- mm/memory.c | 44 ++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 44 insertions(+), 3 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index acd60fbf1a5a..2a16631c1fda 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -566,7 +566,8 @@ struct vm_operations_struct { vm_fault_t (*pfn_mkwrite)(struct vm_fault *vmf); /* called by access_process_vm when get_user_pages() fails, typically - * for use by special VMAs that can switch between memory and hardware + * for use by special VMAs. See also generic_access_phys() for a generic + * implementation useful for any iomem mapping. */ int (*access)(struct vm_area_struct *vma, unsigned long addr, void *buf, int len, int write); diff --git a/mm/memory.c b/mm/memory.c index eeae590e526a..fff817608eb4 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4840,28 +4840,68 @@ int follow_phys(struct vm_area_struct *vma, return ret; } +/** + * generic_access_phys - generic implementation for iomem mmap access + * @vma: the vma to access + * @addr: userspace addres, not relative offset within @vma + * @buf: buffer to read/write + * @len: length of transfer + * @write: set to FOLL_WRITE when writing, otherwise reading + * + * This is a generic implementation for &vm_operations_struct.access for an + * iomem mapping. This callback is used by access_process_vm() when the @vma is + * not page based. + */ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, void *buf, int len, int write) { resource_size_t phys_addr; unsigned long prot = 0; void __iomem *maddr; + pte_t *ptep, pte; + spinlock_t *ptl; int offset = addr & (PAGE_SIZE-1); + int ret = -EINVAL; + + if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) + return -EINVAL; + +retry: + if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) + return -EINVAL; + pte = *ptep; + pte_unmap_unlock(ptep, ptl); - if (follow_phys(vma, addr, write, &prot, &phys_addr)) + prot = pgprot_val(pte_pgprot(pte)); + phys_addr = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; + + if ((write & FOLL_WRITE) && !pte_write(pte)) return -EINVAL; maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot); if (!maddr) return -ENOMEM; + if (follow_pte(vma->vm_mm, addr, &ptep, &ptl)) + goto out_unmap; + + if (!pte_same(pte, *ptep)) { + pte_unmap_unlock(ptep, ptl); + iounmap(maddr); + + goto retry; + } + if (write) memcpy_toio(maddr + offset, buf, len); else memcpy_fromio(buf, maddr + offset, len); + ret = len; + pte_unmap_unlock(ptep, ptl); +out_unmap: iounmap(maddr); - return len; + return ret; } EXPORT_SYMBOL_GPL(generic_access_phys); #endif