linux-kernel - [PATCH v2] coresight: Disable MMIO logging for coresight stm driver

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Message-ID: <20250506075743.1398257-1-quic_jinlmao@quicinc.com>
Date: Tue, 6 May 2025 00:57:43 -0700
From: Mao Jinlong <quic_jinlmao@...cinc.com>
To: 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>,
        Leo Yan <leo.yan@....com>,
        Anshuman Khandual <anshuman.khandual@....com>
CC: Mao Jinlong <quic_jinlmao@...cinc.com>, <coresight@...ts.linaro.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v2] coresight: Disable MMIO logging for coresight stm driver

With MMIO logging enabled, the MMIO access are traced and could be
sent to an STM device. Thus, an STM driver MMIO access could create
circular call chain with MMIO logging. Disable it for STM driver.

[] 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
[] 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>
Reviewed-by: Leo Yan <leo.yan@....com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>
---
Changes in V2:
update the commit message

 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 \
-- 
2.25.1