linux-kernel - [PATCH 17/19] coresight: trbe: Enable circle mode for snapshot

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20251201-trbe_buffer_refactor_v1-1-v1-17-7da32b076b28@arm.com>
Date: Mon, 01 Dec 2025 11:22:07 +0000
From: Leo Yan <leo.yan@....com>
To: Suzuki K Poulose <suzuki.poulose@....com>, 
 Mike Leach <mike.leach@...aro.org>, James Clark <james.clark@...aro.org>, 
 Anshuman Khandual <anshuman.khandual@....com>, 
 Yeoreum Yun <yeoreum.yun@....com>, Will Deacon <will@...nel.org>, 
 Mark Rutland <mark.rutland@....com>, Tamas Petz <tamas.petz@....com>, 
 Tamas Zsoldos <tamas.zsoldos@....com>, 
 Arnaldo Carvalho de Melo <acme@...nel.org>, 
 Namhyung Kim <namhyung@...nel.org>, Jiri Olsa <jolsa@...nel.org>, 
 Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org, 
 Leo Yan <leo.yan@....com>
Subject: [PATCH 17/19] coresight: trbe: Enable circle mode for snapshot

A snapshot session captures trace data only when userspace receives a
signal and disables tracing. Before disabling, enable circle mode
instead of fill mode to avoid unnecessary interrupt handling.

Signed-off-by: Leo Yan <leo.yan@....com>
---
 drivers/hwtracing/coresight/coresight-trbe.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 0551ea9b4f8286c156e3c9c7ac94e2ecd3b9dc3f..ee9993d518d2a41f0d709b7d0690b2dfe0bef2d9 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -635,6 +635,12 @@ static void set_trbe_limit_pointer_enabled(struct trbe_buf *buf)
 	trblimitr &= ~TRBLIMITR_EL1_TM_MASK;
 	trblimitr &= ~TRBLIMITR_EL1_LIMIT_MASK;
 
+	if (buf->snapshot) {
+		trblimitr |= FIELD_PREP(TRBLIMITR_EL1_FM_MASK, TRBLIMITR_EL1_FM_CBUF) |
+			     FIELD_PREP(TRBLIMITR_EL1_TM_MASK, TRBLIMITR_EL1_TM_IGNR);
+		goto enable_trace_buf;
+	}
+
 	if (!buf->trbe_count ||
 	    buf->trbe_write + buf->trbe_count == buf->trbe_limit) {
 		/*
@@ -669,6 +675,7 @@ static void set_trbe_limit_pointer_enabled(struct trbe_buf *buf)
 			     FIELD_PREP(TRBLIMITR_EL1_TM_MASK, TRBLIMITR_EL1_TM_STOP);
 	}
 
+enable_trace_buf:
 	trblimitr |= (addr & PAGE_MASK);
 	set_trbe_enabled(buf->cpudata, trblimitr);
 }

-- 
2.34.1