When specifying a 2GB AUX buffer, the ETR driver ends up allocating only a 1MB buffer instead:

# echo 'file coresight-tmc-etr.c +p' > \ /sys/kernel/debug/dynamic_debug/control # perf record -e cs_etm/@tmc_etr0,timestamp=0/u -C 0 -m ,2G -- test coresight tmc_etr0: allocated buffer of size 1024KB in mode 0

The page index is an 'int' type, and shifting it by PAGE_SHIFT overflows when the resulting value exceeds 2GB. This produces a negative value, causing the driver to fall back to the minimum buffer size (1MB).

Cast the page index to a wider type to accommodate large buffer sizes. Also fix a similar issue in the buffer offset calculation.

Reported-by: Michiel van Tol michiel.vantol@arm.com Fixes: 99443ea19e8b ("coresight: Add generic TMC sg table framework") Fixes: eebe8dbd8630 ("coresight: tmc: Decouple the perf buffer allocation from sysfs mode") Signed-off-by: Leo Yan leo.yan@arm.com --- drivers/hwtracing/coresight/coresight-tmc-etr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index cee82e52c4ea96b035f1db71b2d9a006bfc1c51e..990bbb721e1d712d7b93f1e36087fdaf9d3baa3b 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -154,7 +154,7 @@ tmc_pages_get_offset(struct tmc_pages *tmc_pages, dma_addr_t addr) for (i = 0; i < tmc_pages->nr_pages; i++) { page_start = tmc_pages->daddrs[i]; if (addr >= page_start && addr < (page_start + PAGE_SIZE)) - return i * PAGE_SIZE + (addr - page_start); + return (long)i * PAGE_SIZE + (addr - page_start); }

return -EINVAL; @@ -1381,7 +1381,7 @@ alloc_etr_buf(struct tmc_drvdata *drvdata, struct perf_event *event, node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);

/* Use the minimum limit if the required size is smaller */ - size = nr_pages << PAGE_SHIFT; + size = (ssize_t)nr_pages << PAGE_SHIFT; size = max_t(ssize_t, size, TMC_ETR_PERF_MIN_BUF_SIZE);

/*

--- base-commit: eebe8dbd8630f51cf70b1f68a440cd3d7f7a914d change-id: 20260217-arm_coresight_fix_big_buffer_size-a8a41298369d

Best regards,