linux-kernel - [PATCH] coresight: trbe: Add ISB after TRBLIMITR write

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-Id: <20250609-james-cs-trblimitr-isb-v1-1-3a2aa4ee6770@linaro.org>
Date: Mon, 09 Jun 2025 11:19:05 +0100
From: James Clark <james.clark@...aro.org>
To: Suzuki K Poulose <suzuki.poulose@....com>, 
 Mike Leach <mike.leach@...aro.org>, 
 Alexander Shishkin <alexander.shishkin@...ux.intel.com>, 
 Marc Zyngier <maz@...nel.org>
Cc: coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, James Clark <james.clark@...aro.org>
Subject: [PATCH] coresight: trbe: Add ISB after TRBLIMITR write

DEN0154 states that hardware will be allowed to ignore writes to TRB*
registers while the trace buffer is enabled. Add an ISB to ensure that
it's disabled before clearing the other registers.

This is purely defensive because it's expected that arm_trbe_disable()
would be called before teardown which has the required ISB.

Fixes: a2b579c41fe9 ("coresight: trbe: Remove redundant disable call")
Signed-off-by: James Clark <james.clark@...aro.org>
---
 drivers/hwtracing/coresight/coresight-trbe.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 8267dd1a2130..10f3fb401edf 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -257,6 +257,7 @@ static void trbe_drain_and_disable_local(struct trbe_cpudata *cpudata)
 static void trbe_reset_local(struct trbe_cpudata *cpudata)
 {
 	write_sysreg_s(0, SYS_TRBLIMITR_EL1);
+	isb();
 	trbe_drain_buffer();
 	write_sysreg_s(0, SYS_TRBPTR_EL1);
 	write_sysreg_s(0, SYS_TRBBASER_EL1);

---
base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494
change-id: 20250609-james-cs-trblimitr-isb-523f20d874d6

Best regards,
-- 
James Clark <james.clark@...aro.org>