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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8420EC433F5 for ; Mon, 3 Jan 2022 05:41:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231698AbiACFlM (ORCPT ); Mon, 3 Jan 2022 00:41:12 -0500 Received: from alexa-out-sd-01.qualcomm.com ([199.106.114.38]:62605 "EHLO alexa-out-sd-01.qualcomm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229527AbiACFlL (ORCPT ); Mon, 3 Jan 2022 00:41:11 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1641188471; x=1672724471; h=message-id:date:mime-version:subject:from:to:cc: references:in-reply-to:content-transfer-encoding; bh=ZUtxtdz4uH9rLeuOq9hfgHex7zCJpBmeeoNCCU1r+Yg=; 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<4009226e-76bf-6e37-65be-8942ef7126df@quicinc.com> Date: Mon, 3 Jan 2022 11:11:03 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.1.2 Subject: Re: [PATCHv6 0/5] tracing/rwmmio/arm64: Add support to trace register reads/writes Content-Language: en-US From: Sai Prakash Ranjan To: Will Deacon , Catalin Marinas , Marc Zyngier , Arnd Bergmann , Steven Rostedt CC: gregkh , , , , References: <93ef32a5-013a-fdcf-11bb-6f3c9bc34628@quicinc.com> In-Reply-To: <93ef32a5-013a-fdcf-11bb-6f3c9bc34628@quicinc.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/13/2021 8:58 AM, Sai Prakash Ranjan wrote: > Hi Arnd, > > On 12/7/2021 12:24 PM, Sai Prakash Ranjan wrote: >> Generic MMIO read/write i.e., __raw_{read,write}{b,l,w,q} accessors >> are typically used to read/write from/to memory mapped registers >> and can cause hangs or some undefined behaviour in following cases, >> >> * If the access to the register space is unclocked, for example: if >>    there is an access to multimedia(MM) block registers without MM >>    clocks. >> >> * If the register space is protected and not set to be accessible from >>    non-secure world, for example: only EL3 (EL: Exception level) access >>    is allowed and any EL2/EL1 access is forbidden. >> >> * If xPU(memory/register protection units) is controlling access to >>    certain memory/register space for specific clients. >> >> and more... >> >> Such cases usually results in instant reboot/SErrors/NOC or interconnect >> hangs and tracing these register accesses can be very helpful to debug >> such issues during initial development stages and also in later stages. >> >> So use ftrace trace events to log such MMIO register accesses which >> provides rich feature set such as early enablement of trace events, >> filtering capability, dumping ftrace logs on console and many more. >> >> Sample output: >> >> rwmmio_write: __qcom_geni_serial_console_write+0x160/0x1e0 width=32 >> val=0xa0d5d addr=0xfffffbfffdbff700 >> rwmmio_post_write: __qcom_geni_serial_console_write+0x160/0x1e0 >> width=32 val=0xa0d5d addr=0xfffffbfffdbff700 >> rwmmio_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 >> addr=0xfffffbfffdbff610 >> rwmmio_post_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 >> val=0x0 addr=0xfffffbfffdbff610 >> >> This series is a follow-up for the series [1] and a recent series [2] >> making use >> of both. >> >> [1] >> https://lore.kernel.org/lkml/cover.1536430404.git.saiprakash.ranjan@codeaurora.org/ >> [2] >> https://lore.kernel.org/lkml/1604631386-178312-1-git-send-email-psodagud@codeaurora.org/ >> >> Note in previous v4 version, Arnd suggested to benchmark and compare >> size with callback >> based implementation, please see [3] for more details on that with >> brief comparison below. >> >> >> **Inline version with CONFIG_FTRACE=y and CONFIG_TRACE_MMIO_ACCESS=y** >> $ size vmlinux >>     text           data             bss     dec hex         filename >>   23884219        14284468         532568 38701255 24e88c7        >> vmlinux >> >> **Callback version with CONFIG_FTRACE=y and CONFIG_TRACE_MMIO_ACCESS=y** >> $ size vmlinux >>      text          data             bss     dec hex        filename >>   24108179        14279596         532568 38920343 251e097       vmlinux >> >> $ ./scripts/bloat-o-meter inline-vmlinux callback-vmlinux >> add/remove: 8/3 grow/shrink: 4889/89 up/down: 242244/-11564 (230680) >> Total: Before=25812612, After=26043292, chg +0.89% >> >> [3] >> https://lore.kernel.org/lkml/466449a1-36da-aaa9-7e4f-477f36b52c9e@quicinc.com/ >> >> Changes in v6: >>   * Implemented suggestions by Arnd Bergmann: >>     - Use arch independent IO barriers in arm64/asm >>     - Add ARCH_HAVE_TRACE_MMIO_ACCESS >>     - Add post read and post write logging support >>     - Remove tracepoint_active check >>   * Fix build error reported by kernel test robot. >> >> Changes in v5: >>   * Move arm64 to use asm-generic provided high level MMIO accessors >> (Arnd). >>   * Add inline logging for MMIO relaxed and non-relaxed accessors. >>   * Move nVHE KVM comment to makefile (Marc). >>   * Fix overflow warning due to switch to inline accessors instead of >> macro. >>   * Modify trace event field to include caller and parent details for >> more detailed logs. >> >> Changes in v4: >>   * Drop dynamic debug based filter support since that will be >> developed later with >>     the help from Steven (Ftrace maintainer). >>   * Drop value passed to writel as it is causing hangs when tracing >> is enabled. >>   * Code cleanup for trace event as suggested by Steven for earlier >> version. >>   * Fixed some build errors reported by 0-day bot. >> >> Changes in v3: >>   * Create a generic mmio header for instrumented version (Earlier >> suggested in [1] >>     by Will Deacon and recently [2] by Greg to have a generic version >> first). >>   * Add dynamic debug support to filter out traces which can be very >> useful for targeted >>     debugging specific to subsystems or drivers. >>   * Few modifications to the rwmmio trace event fields to include the >> mmio width and print >>     addresses in hex. >>   * Rewrote commit msg to explain some more about usecases. >> >> Prasad Sodagudi (1): >>    tracing: Add register read/write tracing support >> >> Sai Prakash Ranjan (4): >>    arm64: io: Use asm-generic high level MMIO accessors >>    irqchip/tegra: Fix overflow implicit truncation warnings >>    drm/meson: Fix overflow implicit truncation warnings >>    asm-generic/io: Add logging support for MMIO accessors >> >>   arch/Kconfig                      |   3 + >>   arch/arm64/Kconfig                |   1 + >>   arch/arm64/include/asm/io.h       |  41 +++-------- >>   arch/arm64/kvm/hyp/nvhe/Makefile  |   7 +- >>   drivers/gpu/drm/meson/meson_viu.c |  22 +++--- >>   drivers/irqchip/irq-tegra.c       |  10 +-- >>   include/asm-generic/io.h          |  81 +++++++++++++++++++-- >>   include/trace/events/rwmmio.h     | 112 ++++++++++++++++++++++++++++++ >>   kernel/trace/Kconfig              |   7 ++ >>   kernel/trace/Makefile             |   1 + >>   kernel/trace/trace_readwrite.c    |  47 +++++++++++++ >>   11 files changed, 278 insertions(+), 54 deletions(-) >>   create mode 100644 include/trace/events/rwmmio.h >>   create mode 100644 kernel/trace/trace_readwrite.c >> > > Does this version look good to you? From the other mail thread it > seems Catalin > is ok with your suggested change. Kernel test robot hasn't come with > any build error > reports so far, I have fixed the previous reported one in meson drm > driver. > > Thanks, > Sai Any more comments for this version? Thanks, Sai