[PATCH 5.4 116/154] coresight: catu: Fix number of pages while using 64k pages

Greg Kroah-Hartman
2025-04-08T12:09:11Z

From: Ilkka Koskinen <ilkka@os.amperecomputing.com>

[ Upstream commit 0e14e062f5ff98aa15264dfa87c5f5e924028561 ]

Trying to record a trace on kernel with 64k pages resulted in -ENOMEM.
This happens due to a bug in calculating the number of table pages, which
returns zero. Fix the issue by rounding up.

$ perf record --kcore -e cs_etm/@tmc_etr55,cycacc,branch_broadcast/k --per-thread taskset --cpu-list 1 dd if=/dev/zero of=/dev/null
failed to mmap with 12 (Cannot allocate memory)

Fixes: 8ed536b1e283 ("coresight: catu: Add support for scatter gather tables")
Signed-off-by: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20250109215348.5483-1-ilkka@os.amperecomputing.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/hwtracing/coresight/coresight-catu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-catu.c b/drivers/hwtracing/coresight/coresight-catu.c
index 16ebf38a9f664..da205738e8c96 100644
--- a/drivers/hwtracing/coresight/coresight-catu.c
+++ b/drivers/hwtracing/coresight/coresight-catu.c
@@ -267,7 +267,7 @@ catu_init_sg_table(struct device *catu_dev, int node,
* Each table can address upto 1MB and we can have
* CATU_PAGES_PER_SYSPAGE tables in a system page.
*/
- nr_tpages = DIV_ROUND_UP(size, SZ_1M) / CATU_PAGES_PER_SYSPAGE;
+ nr_tpages = DIV_ROUND_UP(size, CATU_PAGES_PER_SYSPAGE * SZ_1M);
catu_table = tmc_alloc_sg_table(catu_dev, node, nr_tpages,
size >> PAGE_SHIFT, pages);
if (IS_ERR(catu_table))
--
2.39.5