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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 19232C2BB1D for ; Mon, 16 Mar 2020 15:33:16 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 C859420663 for ; Mon, 16 Mar 2020 15:33:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="ids0fWwC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C859420663 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-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=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:Reply-To:Content-ID:Content-Description :Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ucGwAWuqdJDYKtSAVZ0u6Bv0/jXWcdWqKUAUIQXyWu0=; b=ids0fWwCCQGn8F LO1o5lgh6mLkB3GOqV/iG9JYJisu02DSFQb0MzsJpRiVygdQfBPH4ty8XtSEniwOrzeVhewC4pgZY BWMh0Sx62j8xATbwUcn2romB8A+xFgwCO1RX8oV87cdmREMgwk0Z7oyLP3OozJudJHlnDrSy8R+pk viaoAePpCYlqRlp23wlcw8/zNbPckbLooQv+fnxKryESsvftArZrDztYbN6ekTJcf1ynQKQZV1HwX eY4jFPl5I5Z16T3jICImWI4fvzlCQUX0D681ec8y2/78WWCWQC6w1AFsYLV+VIz68UetYz2V6X6k+ dfukS7tzL9MD/5d5EYKw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jDrjs-00037s-RG; Mon, 16 Mar 2020 15:33:12 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jDrjp-00036f-21 for linux-arm-kernel@lists.infradead.org; Mon, 16 Mar 2020 15:33:10 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7F0F41FB; Mon, 16 Mar 2020 08:33:08 -0700 (PDT) Received: from [10.37.9.38] (unknown [10.37.9.38]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4EBBC3F534; Mon, 16 Mar 2020 08:33:03 -0700 (PDT) Subject: Re: [PATCH v3 18/26] arm64: Introduce asm/vdso/processor.h To: Catalin Marinas References: <20200313154345.56760-1-vincenzo.frascino@arm.com> <20200313154345.56760-19-vincenzo.frascino@arm.com> <20200315182950.GB32205@mbp> <20200316103437.GD3005@mbp> <77a2e91a-58f4-3ba3-9eef-42d6a8faf859@arm.com> <20200316112205.GE3005@mbp> <9a0a9285-8a45-4f65-3a83-813cabd0f0d3@arm.com> <20200316144346.GF3005@mbp> From: Vincenzo Frascino Message-ID: <427064ee-45df-233c-0281-69e3d62ba784@arm.com> Date: Mon, 16 Mar 2020 15:33:30 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200316144346.GF3005@mbp> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200316_083309_190285_37A81F56 X-CRM114-Status: GOOD ( 21.02 ) 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: Mark Rutland , Dmitry Safonov <0x7f454c46@gmail.com>, linux-mips@vger.kernel.org, Will Deacon , linux-arch@vger.kernel.org, Marc Zyngier , x86@kernel.org, Russell King , clang-built-linux@googlegroups.com, Ingo Molnar , Kees Cook , Arnd Bergmann , Will Deacon , Borislav Petkov , Andy Lutomirski , Thomas Gleixner , Peter Collingbourne , linux-arm-kernel@lists.infradead.org, Andrei Vagin , Stephen Boyd , Nick Desaulniers , linux-kernel@vger.kernel.org, Mark Salyzyn , Paul Burton Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 3/16/20 2:43 PM, Catalin Marinas wrote[...] >> To me does not seem optimized out. Which version of the compiler are you using? > > I misread the #ifdef'ery in asm/processor.h. So with 4K pages, > TASK_SIZE_32 is (1UL<<32)-PAGE_SIZE. However, with 64K pages _and_ > CONFIG_KUSER_HELPERS, TASK_SIZE_32 is 1UL<<32 and the check is removed > by the compiler. > > With the 4K build, __vdso_clock_gettime starts as: > > 00000194 <__vdso_clock_gettime>: > 194: f511 5f80 cmn.w r1, #4096 ; 0x1000 > 198: d214 bcs.n 1c4 <__vdso_clock_gettime+0x30> > 19a: b5b0 push {r4, r5, r7, lr} > ... > 1c4: f06f 000d mvn.w r0, #13 > 1c8: 4770 bx lr > > With 64K pages: > > 00000194 <__vdso_clock_gettime>: > 194: b5b0 push {r4, r5, r7, lr} > ... > 1be: bdb0 pop {r4, r5, r7, pc} > > I haven't tried but it's likely that the vdsotest fails with 64K pages > and compat enabled (requires EXPERT). > This makes more sense. Thanks for the clarification. I agree on the behavior of 64K pages and I think as well that the "compatibility" issue is still there. However as you correctly stated in your first email arm32 never supported 16K or 64K pages, hence I think we should not be concerned about compatibility in this cases. To make it more explicit we could make COMPAT_VDSO on arm64 depend on ARM64_4K_PAGES. What do you think? >> Please find below the list of errors for clock_gettime (similar for the other): >> >> passing UINTPTR_MAX to clock_gettime (VDSO): terminated by unexpected signal 7 >> clock-gettime-monotonic/abi: 1 failures/inconsistencies encountered > > Ah, so it uses UINTPTR_MAX in the test. Fair enough but I don't think > the arm64 check is entirely useful. On arm32, the check was meant to > return -EFAULT for addresses beyond TASK_SIZE that may enter into the > kernel or module space. On arm64 compat, the kernel space is well above > the reach of the 32-bit code. > > If you want to preserve some compatibility for this specific test, what > about checking for wrapping around 0, I think it would make more sense. > Something like: > > if ((u32)ts > UINTPTR_MAX - sizeof(*ts) + 1) > Ok, sounds good to me. But it is something that this patch series inherited, hence I would prefer to send a separate patch that introduces what you are proposing and removes TASK_SIZE_32 from the headers. How does it sound? -- Regards, Vincenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel