Hi,
On Mon, Mar 1, 2021 at 11:05 AM Sai Prakash Ranjan saiprakash.ranjan@codeaurora.org wrote:
On production systems with ETMs enabled, it is preferred to exclude kernel mode(NS EL1) tracing for security concerns and support only userspace(NS EL0) tracing. Perf subsystem interface uses the newly introduced kernel config CONFIG_EXCLUDE_KERNEL_PMU_TRACE to exclude kernel mode tracing, but there is an additional interface via sysfs for ETMs which also needs to be handled to exclude kernel mode tracing. So we use this same generic kernel config to handle the sysfs mode of tracing. This config is disabled by default and would not affect the current configuration which has both kernel and userspace tracing enabled by default.
Tested-by: Denis Nikitin denik@chromium.org Signed-off-by: Sai Prakash Ranjan saiprakash.ranjan@codeaurora.org
drivers/hwtracing/coresight/coresight-etm4x-core.c | 6 +++++- drivers/hwtracing/coresight/coresight-etm4x-sysfs.c | 6 ++++++ 2 files changed, 11 insertions(+), 1 deletion(-)
Not that I'm an expert in the perf subsystem, but the concern I had with v1 is now addressed. FWIW this seems fine to me now.
Reviewed-by: Douglas Anderson dianders@chromium.org
--- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c @@ -296,6 +296,12 @@ static ssize_t mode_store(struct device *dev, if (kstrtoul(buf, 16, &val)) return -EINVAL;
if (IS_ENABLED(CONFIG_EXCLUDE_KERNEL_PMU_TRACE) && (!(val & ETM_MODE_EXCL_KERN))) {dev_warn(dev,"Kernel mode tracing is not allowed, check your kernel config\n");
slight nit that I think your string needs to be indented by 1 space. ;-)