From patchwork Fri Oct 30 10:08:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Daniel Vetter X-Patchwork-Id: 11869073 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=-12.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 942FCC6379F for ; Fri, 30 Oct 2020 10:09:03 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (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 24FE322228 for ; Fri, 30 Oct 2020 10:09:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="Gcc++IpN" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 24FE322228 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ffwll.ch Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 4DAB76ED90; Fri, 30 Oct 2020 10:08:57 +0000 (UTC) Received: from mail-wr1-x442.google.com (mail-wr1-x442.google.com [IPv6:2a00:1450:4864:20::442]) by gabe.freedesktop.org (Postfix) with ESMTPS id 626FB6ED88 for ; Fri, 30 Oct 2020 10:08:49 +0000 (UTC) Received: by mail-wr1-x442.google.com with SMTP id s9so5780643wro.8 for ; Fri, 30 Oct 2020 03:08:49 -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=HiI1+lLgMnsDQrYrNhRZjnVGpkNPEsmr7OdQwQZ1pJM=; b=Gcc++IpNNygNqtJu4MOWlOxXDTLkz8kWRrWBTguDYU0QSDOK1lmStqYhCY80JP1x87 nnoIM/kxhaqSCxhTbtNStA1+u8N8i8vvYmmr+2qlMbzhOp1A6XcFYXNVmwMv8phCp320 uR7glXXilJAM58uJT7pnvEqFSZFFav+qZ48X4= 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=HiI1+lLgMnsDQrYrNhRZjnVGpkNPEsmr7OdQwQZ1pJM=; b=rAgCEMZiOr//Bo12HW+dQXRJuCFnOq5erXt65BTWcgqvnCE8SBy8KgSzhUoCKmlnTw hgXMgbfva6yG8NjN3TxhtVx0z7I7k6+5sp1wokfphCR/+m6CudytCzBul/ra4CzwovTQ N+SG6+zcC3ao6Kb2O5e1tnEG61XEWuxjjoxbjEihgwLmhcafFMhu6RitMNaJlWZr6Xwp OhWvyDWld2HQHAK+TDBtAwAvA/bJd/3qw33S7l9zTPhtAPu5cB9qS/4Rj3PmL5KFAbnN GwhLgSYFW/ds2I6rnRUGRAeCi7bkO3HIJZ4U5955I9dDIspJdwLyXXtmBXHRq860UDLv ivBg== X-Gm-Message-State: AOAM530JDQG8GAa3D15eevqQLRj8IJQGh1z9UKRgQhl4xqaSoFTrrz3A 7ltoBc5sFBmwGeSsReYBysN7zAtHRIeySH3Y X-Google-Smtp-Source: ABdhPJz2EbQLLd9y23l7XD4h1NQjvIRRCqqxxXIiiwxNslHpfrfcptIiI2iHPCasY7SN1JKAQAi14g== X-Received: by 2002:a5d:4d8a:: with SMTP id b10mr2128836wru.5.1604052527823; Fri, 30 Oct 2020 03:08:47 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id v189sm4430947wmg.14.2020.10.30.03.08.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Oct 2020 03:08:46 -0700 (PDT) From: Daniel Vetter To: DRI Development , LKML Subject: [PATCH v5 07/15] mm: Close race in generic_access_phys Date: Fri, 30 Oct 2020 11:08:07 +0100 Message-Id: <20201030100815.2269-8-daniel.vetter@ffwll.ch> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201030100815.2269-1-daniel.vetter@ffwll.ch> References: <20201030100815.2269-1-daniel.vetter@ffwll.ch> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-samsung-soc@vger.kernel.org, Jan Kara , Kees Cook , kvm@vger.kernel.org, Jason Gunthorpe , Dave Airlie , Daniel Vetter , Chris Wilson , linux-mm@kvack.org, =?utf-8?b?SsOp?= =?utf-8?b?csO0bWUgR2xpc3Nl?= , John Hubbard , Daniel Vetter , Dan Williams , Andrew Morton , linux-arm-kernel@lists.infradead.org, linux-media@vger.kernel.org Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" 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 Cc: Chris Wilson Signed-off-by: Daniel Vetter --- v2: Fix inversion in the retry check (John). v4: While at it, use offset_in_page (Chris Wilson) --- include/linux/mm.h | 3 ++- mm/memory.c | 46 +++++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 45 insertions(+), 4 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 179dbb78d08d..83d0be101a38 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -574,7 +574,8 @@ 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 c48f8df6e502..ac32039ce941 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4847,28 +4847,68 @@ 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; - int offset = addr & (PAGE_SIZE-1); + pte_t *ptep, pte; + spinlock_t *ptl; + int offset = offset_in_page(addr); + 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