diff options
| author | Leo Yan <leo.yan@arm.com> | 2026-07-02 18:05:21 +0100 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2026-07-31 13:56:58 +0000 |
| commit | fcc5eaea2d234162dfb8258372dd897bc2a1b862 (patch) | |
| tree | 2c4ce3863c19e38850361706e10165bff15c8c10 | |
| parent | 49f2413f9b55dd975fb7d874c1fd35cf6a7335c6 (diff) | |
perf: arm_spe: Make wakeup range check overflow safe
The current code checks whether the wakeup point is in the current
writable range by comparing it with handle->head + handle->size.
The perf AUX head is a monotonically increasing index, so that addition
can overflow when head is close to ULONG_MAX. In that case, a wakeup
point which is still inside the free space range can be missed.
Use unsigned subtraction to compare the distance from head to wakeup
against the handle->size. This can dismiss the issue when addition
overflow.
This is unlikely to happen in practice, but the change makes the
watermark check logically correct.
Fixes: d5d9696b0380 ("drivers/perf: Add support for ARMv8.2 Statistical Profiling Extension")
Signed-off-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | drivers/perf/arm_spe_pmu.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c index dbd0da111639..b64cf2313a20 100644 --- a/drivers/perf/arm_spe_pmu.c +++ b/drivers/perf/arm_spe_pmu.c @@ -577,7 +577,7 @@ static u64 __arm_spe_pmu_next_off(struct perf_output_handle *handle) * the page boundary following it. Keep the tail boundary if * that's lower. */ - 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)); if (limit > head) |