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=-3.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 10DC2C04EB8 for ; Wed, 12 Dec 2018 07:21:33 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (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 8B9212084E for ; Wed, 12 Dec 2018 07:21:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B9212084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=c-s.fr Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 43F7XV3pkVzDqsZ for ; Wed, 12 Dec 2018 18:21:30 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=c-s.fr Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=c-s.fr (client-ip=93.17.236.30; helo=pegase1.c-s.fr; envelope-from=christophe.leroy@c-s.fr; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=c-s.fr Received: from pegase1.c-s.fr (pegase1.c-s.fr [93.17.236.30]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 43F7V84DhRzDqcq for ; Wed, 12 Dec 2018 18:19:27 +1100 (AEDT) Received: from localhost (mailhub1-int [192.168.12.234]) by localhost (Postfix) with ESMTP id 43F7V31tlnz9v0fb; Wed, 12 Dec 2018 08:19:23 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at c-s.fr Received: from pegase1.c-s.fr ([192.168.12.234]) by localhost (pegase1.c-s.fr [192.168.12.234]) (amavisd-new, port 10024) with ESMTP id AiQMlPEefn9W; Wed, 12 Dec 2018 08:19:23 +0100 (CET) Received: from messagerie.si.c-s.fr (messagerie.si.c-s.fr [192.168.25.192]) by pegase1.c-s.fr (Postfix) with ESMTP id 43F7V317xXz9v0fZ; Wed, 12 Dec 2018 08:19:23 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by messagerie.si.c-s.fr (Postfix) with ESMTP id 125CF8B82A; Wed, 12 Dec 2018 08:19:24 +0100 (CET) X-Virus-Scanned: amavisd-new at c-s.fr Received: from messagerie.si.c-s.fr ([127.0.0.1]) by localhost (messagerie.si.c-s.fr [127.0.0.1]) (amavisd-new, port 10023) with ESMTP id r5jEYM3B3tVG; Wed, 12 Dec 2018 08:19:23 +0100 (CET) Received: from PO15451 (unknown [192.168.4.90]) by messagerie.si.c-s.fr (Postfix) with ESMTP id A2BCE8B825; Wed, 12 Dec 2018 08:19:23 +0100 (CET) Subject: Re: [PATCH v3] powerpc: implement CONFIG_DEBUG_VIRTUAL To: Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras References: <87va3zwq1t.fsf@concordia.ellerman.id.au> From: Christophe Leroy Message-ID: <32b00148-214c-44db-e9cf-fa4caa2547e8@c-s.fr> Date: Wed, 12 Dec 2018 08:19:22 +0100 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: <87va3zwq1t.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Le 12/12/2018 à 01:23, Michael Ellerman a écrit : > Christophe Leroy writes: > >> This patch implements CONFIG_DEBUG_VIRTUAL to warn about >> incorrect use of virt_to_phys() and page_to_phys() >> >> Below is the result of test_debug_virtual: >> >> [ 1.438746] WARNING: CPU: 0 PID: 1 at ./arch/powerpc/include/asm/io.h:808 test_debug_virtual_init+0x3c/0xd4 >> [ 1.448156] CPU: 0 PID: 1 Comm: swapper Not tainted 4.20.0-rc5-00560-g6bfb52e23a00-dirty #532 >> [ 1.457259] NIP: c066c550 LR: c0650ccc CTR: c066c514 >> [ 1.462257] REGS: c900bdb0 TRAP: 0700 Not tainted (4.20.0-rc5-00560-g6bfb52e23a00-dirty) >> [ 1.471184] MSR: 00029032 CR: 48000422 XER: 20000000 >> [ 1.477811] >> [ 1.477811] GPR00: c0650ccc c900be60 c60d0000 00000000 006000c0 c9000000 00009032 c7fa0020 >> [ 1.477811] GPR08: 00002400 00000001 09000000 00000000 c07b5d04 00000000 c00037d8 00000000 >> [ 1.477811] GPR16: 00000000 00000000 00000000 00000000 c0760000 c0740000 00000092 c0685bb0 >> [ 1.477811] GPR24: c065042c c068a734 c0685b8c 00000006 00000000 c0760000 c075c3c0 ffffffff >> [ 1.512711] NIP [c066c550] test_debug_virtual_init+0x3c/0xd4 >> [ 1.518315] LR [c0650ccc] do_one_initcall+0x8c/0x1cc >> [ 1.523163] Call Trace: >> [ 1.525595] [c900be60] [c0567340] 0xc0567340 (unreliable) >> [ 1.530954] [c900be90] [c0650ccc] do_one_initcall+0x8c/0x1cc >> [ 1.536551] [c900bef0] [c0651000] kernel_init_freeable+0x1f4/0x2cc >> [ 1.542658] [c900bf30] [c00037ec] kernel_init+0x14/0x110 >> [ 1.547913] [c900bf40] [c000e1d0] ret_from_kernel_thread+0x14/0x1c >> [ 1.553971] Instruction dump: >> [ 1.556909] 3ca50100 bfa10024 54a5000e 3fa0c076 7c0802a6 3d454000 813dc204 554893be >> [ 1.564566] 7d294010 7d294910 90010034 39290001 <0f090000> 7c3e0b78 955e0008 3fe0c062 >> [ 1.572425] ---[ end trace 6f6984225b280ad6 ]--- >> [ 1.577467] PA: 0x09000000 for VA: 0xc9000000 >> [ 1.581799] PA: 0x061e8f50 for VA: 0xc61e8f50 >> >> Signed-off-by: Christophe Leroy >> --- >> v3: Added missing linux/mm.h >> I realised that a driver may use DMA on stack after checking with virt_addr_valid(), so the new >> verification might induce false positives. I remove it for now, will add it again later in a more >> controled way. > > What is this comment referring to? > > I can't see any difference to v2 except the linux/mm.h include. v2 was: @@ -804,6 +806,11 @@ extern void __iounmap_at(void *ea, unsigned long size); */ static inline unsigned long virt_to_phys(volatile void * address) { + if (IS_ENABLED(CONFIG_DEBUG_VIRTUAL) && + !WARN_ON(IS_ENABLED(CONFIG_HAVE_ARCH_VMAP_STACK) && current->pid && + object_is_on_stack((const void*)address))) + WARN_ON(!virt_addr_valid(address)); + return __pa((unsigned long)address); } v3 is: (same as v1) @@ -804,6 +806,8 @@ extern void __iounmap_at(void *ea, unsigned long size); */ static inline unsigned long virt_to_phys(volatile void * address) { + WARN_ON(IS_ENABLED(CONFIG_DEBUG_VIRTUAL) && !virt_addr_valid(address)); + return __pa((unsigned long)address); } The idea in v2 was to detect objects on stack used for DMA before activating CONFIG_VMAP_STACK, but if the driver uses virt_addr_valid() to decide if it can DMA map it, then we'll get false positives. So I think this should be added with a dedicated DEBUG CONFIG option, not implicitely. Christophe