[PATCH] coresight: catu: Fix number of pages while using 64k pages

Ilkka Koskinen ilkka at os.amperecomputing.com
Thu Jan 9 13:53:48 PST 2025


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)

Signed-off-by: Ilkka Koskinen <ilkka at os.amperecomputing.com>
---
 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 275cc0d9f505..3378bb77e6b4 100644
--- a/drivers/hwtracing/coresight/coresight-catu.c
+++ b/drivers/hwtracing/coresight/coresight-catu.c
@@ -269,7 +269,7 @@ 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))
-- 
2.47.0




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