linux-kernel - Re: [PATCH] coresight: Disable MMIO logging for coresight stm driver

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Message-ID: <911d8ce8-9b2e-4c86-ac56-aae523adfe36@arm.com>
Date: Tue, 6 May 2025 09:27:25 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Mao Jinlong <quic_jinlmao@...cinc.com>,
 Suzuki K Poulose <suzuki.poulose@....com>, Mike Leach
 <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>,
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] coresight: Disable MMIO logging for coresight stm driver



On 4/30/25 16:33, Mao Jinlong wrote:
> When read/write registers with readl_relaxed and writel_relaxed,
> log_read_mmio and log_write_mmio will be called. If mmio trace
> is enabled to STM, STM driver will write the register to send the
> trace and writel_relaxed will be called again. The circular call
> like callstack below will happen. Disable mmio logging for stm
> driver to avoid this issue.
> 
> [] stm_source_write[stm_core]+0xc4
> [] stm_ftrace_write[stm_ftrace]+0x40
> [] trace_event_buffer_commit+0x238
> [] trace_event_raw_event_rwmmio_rw_template+0x8c
> [] log_post_write_mmio+0xb4
> [] writel_relaxed[coresight_stm]+0x80
> [] stm_generic_packet[coresight_stm]+0x1a8
> [] stm_data_write[stm_core]+0x78
> [] ost_write[stm_p_ost]+0xc8
> [] stm_source_write[stm_core]+0x7c
> [] stm_ftrace_write[stm_ftrace]+0x40
> [] trace_event_buffer_commit+0x238
> [] trace_event_raw_event_rwmmio_read+0x84
> [] log_read_mmio+0xac
> [] readl_relaxed[coresight_tmc]+0x50
> 
> Signed-off-by: Mao Jinlong <quic_jinlmao@...cinc.com>
> ---
>  drivers/hwtracing/coresight/Makefile | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> index 4ba478211b31..f3158266f75e 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -22,6 +22,8 @@ condflags := \
>  	$(call cc-option, -Wstringop-truncation)
>  subdir-ccflags-y += $(condflags)
>  
> +CFLAGS_coresight-stm.o := -D__DISABLE_TRACE_MMIO__
> +
>  obj-$(CONFIG_CORESIGHT) += coresight.o
>  coresight-y := coresight-core.o  coresight-etm-perf.o coresight-platform.o \
>  		coresight-sysfs.o coresight-syscfg.o coresight-config.o \

As Suzuki mentioned, please do update the commit message.

Otherwise LGTM.

Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>