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15.2.986.22; Fri, 8 Apr 2022 04:17:25 -0700 From: Sai Prakash Ranjan To: CC: , , , , , , , , , , Subject: Re: [PATCHv10 0/6] lib/rwmmio/arm64: Add support to trace register reads/writes Date: Fri, 8 Apr 2022 16:47:07 +0530 Message-ID: <20220408111707.2488-1-quic_saipraka@quicinc.com> X-Mailer: git-send-email 2.33.1 In-Reply-To: References: MIME-Version: 1.0 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) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220408_041734_792660_298DEE27 X-CRM114-Status: GOOD ( 28.16 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Arnd, On 2/24/2022 11:37 AM, 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 v10: > * Use GENMASK(31, 0) for -Woverflow warning in irqchip tegra driver (Marc). > * Convert ETM4x ARM64 driver to use asm-generic IO memory barriers (Catalin). > * Collect ack from Catalin for arm64 change. > > Changes in v9: > * Use TRACE_EVENT_CLASS for rwmmio_write and post_write (Steven Rostedt). > > Changes in v8: > * Fix build error reported by kernel test robot. > > Changes in v7: > * Use lib/ instead of kernel/trace/ based on review comment by Steven Rostedt. > > 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): > lib: Add register read/write tracing support > > Sai Prakash Ranjan (5): > arm64: io: Use asm-generic high level MMIO accessors > coresight: etm4x: Use asm-generic IO memory barriers > 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 ++--- > .../coresight/coresight-etm4x-core.c | 8 +- > drivers/hwtracing/coresight/coresight-etm4x.h | 8 +- > drivers/irqchip/irq-tegra.c | 10 +- > include/asm-generic/io.h | 82 +++++++++++++++- > include/trace/events/rwmmio.h | 97 +++++++++++++++++++ > lib/Kconfig | 7 ++ > lib/Makefile | 2 + > lib/trace_readwrite.c | 47 +++++++++ > 13 files changed, 273 insertions(+), 62 deletions(-) > create mode 100644 include/trace/events/rwmmio.h > create mode 100644 lib/trace_readwrite.c > > > base-commit: 754e0b0e35608ed5206d6a67a791563c631cec07 Gentle ping, could you please take a look at this, would appreciate your reviews. Thanks, Sai _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel