From: Leo Yan <leo.yan@arm.com>
To: Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@arm.com>,
James Clark <james.clark@linaro.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Tamas Petz <tamas.petz@arm.com>,
Tamas Zsoldos <tamas.zsoldos@arm.com>,
Suyash Mahar <smahar@meta.com>, Amir Ayupov <aaupov@fb.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, coresight@lists.linaro.org,
Leo Yan <leo.yan@arm.com>
Subject: [PATCH v2 02/23] coresight: trbe: Make watermark range check overflow safe in __trbe_normal_offset()
Date: Fri, 16 Oct 2026 17:55:00 +0100 [thread overview]
Message-ID: <20261016-trbe_enable_disable_irq_handle_refactor-v2-2-3f57cf3199b1@arm.com> (raw)
In-Reply-To: <20261016-trbe_enable_disable_irq_handle_refactor-v2-0-3f57cf3199b1@arm.com>
The current code checks whether the wakeup point lies before the current
tail by comparing against handle->head + handle->size. That addition can
overflow when the monotonically increasing perf AUX head is close to
ULONG_MAX, causing a valid wakeup point in the current writable range to
be missed.
Use unsigned subtraction to compare the distance from head to wakeup
against the buffer size instead. This keeps the check correct across
potential wrap.
Signed-off-by: Leo Yan <leo.yan@arm.com>
---
drivers/hwtracing/coresight/coresight-trbe.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index eca8e13a97447b46a4b383049aacb3fa7ad3c329..02d12445763a86d58c79bdf5143f761827456bc3 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -526,7 +526,7 @@ static unsigned long __trbe_normal_offset(struct perf_output_handle *handle)
* +----|---------------|-------|-------+
* trbe_base limit trbe_base + nr_pages
*/
- if (handle->wakeup < (handle->head + handle->size) && head <= wakeup)
+ if ((handle->wakeup - handle->head) < handle->size && head <= wakeup)
limit = min(limit, round_up(wakeup, PAGE_SIZE));
/*
--
2.34.1
next prev parent reply other threads:[~2026-10-16 16:55 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-16 16:54 [PATCH v2 00/23] coresight: trbe: Refactor buffer and IRQ handling Leo Yan
2026-10-16 16:54 ` [PATCH v2 01/23] arm64/sysreg: Define TRBSR_EL1.EC event classes Leo Yan
2026-10-16 16:55 ` Leo Yan [this message]
2026-10-16 16:55 ` [PATCH v2 03/23] coresight: trbe: Use helpers for checking errata Leo Yan
2026-10-16 16:55 ` [PATCH v2 04/23] coresight: trbe: Check the buffer association before IRQ validation Leo Yan
2026-10-16 16:55 ` [PATCH v2 05/23] coresight: trbe: Validate perf handle before using sink data Leo Yan
2026-10-16 16:55 ` [PATCH v2 06/23] coresight: trbe: Drop redundant disable from enable path Leo Yan
2026-10-16 16:55 ` [PATCH v2 07/23] coresight: trbe: Publish the session after successful enable Leo Yan
2026-10-16 16:55 ` [PATCH v2 08/23] coresight: trbe: Clear stale external abort status Leo Yan
2026-10-16 16:55 ` [PATCH v2 09/23] coresight: trbe: Clear TRBSR status at stop sites Leo Yan
2026-10-16 16:55 ` [PATCH v2 10/23] coresight: trbe: Drop redundant disables Leo Yan
2026-10-16 16:55 ` [PATCH v2 11/23] coresight: trbe: Assign the perf handle in enable and disable Leo Yan
2026-10-16 16:55 ` [PATCH v2 12/23] coresight: trbe: Decode TRBSR status codes Leo Yan
2026-10-16 16:55 ` [PATCH v2 13/23] coresight: trbe: Simplify wrap status handling Leo Yan
2026-10-16 16:55 ` [PATCH v2 14/23] coresight: trbe: Treat access not allowed stops as fatal Leo Yan
2026-10-16 16:55 ` [PATCH v2 15/23] coresight: trbe: Report truncated trace on buffer update errors Leo Yan
2026-10-16 16:55 ` [PATCH v2 16/23] coresight: trbe: Always classify TRBSR when updating buffer Leo Yan
2026-10-16 16:55 ` [PATCH v2 17/23] coresight: trbe: Calculate trace size across buffer wrap Leo Yan
2026-10-16 16:55 ` [PATCH v2 18/23] coresight: trbe: Keep the perf handle in per-CPU data Leo Yan
2026-10-16 16:55 ` [PATCH v2 19/23] coresight: trbe: Reload the AUX buffer on overflow restart Leo Yan
2026-10-16 16:55 ` [PATCH v2 20/23] coresight: trbe: Add fault action argument to trbe_handle_overflow() Leo Yan
2026-10-16 16:55 ` [PATCH v2 21/23] coresight: trbe: Read TRBSR after prohibiting and flushing trace Leo Yan
2026-10-16 16:55 ` [PATCH v2 22/23] coresight: trbe: Restart trace source for stopped buffers Leo Yan
2026-10-16 16:55 ` [PATCH v2 23/23] coresight: trbe: Report trace gaps with PARTIAL instead of COLLISION Leo Yan
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