Hi, On Mon, Mar 1, 2021 at 11:05 AM Sai Prakash Ranjan <saiprakash.ran...@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. > > Signed-off-by: Sai Prakash Ranjan <saiprakash.ran...@codeaurora.org> > --- > drivers/hwtracing/coresight/coresight-etm3x-core.c | 3 +++ > drivers/hwtracing/coresight/coresight-etm3x-sysfs.c | 6 ++++++ > 2 files changed, 9 insertions(+)
Reviewed-by: Douglas Anderson <diand...@chromium.org> > diff --git a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c > b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c > index e8c7649f123e..f522fc2e01b3 100644 > --- a/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c > +++ b/drivers/hwtracing/coresight/coresight-etm3x-sysfs.c > @@ -116,6 +116,12 @@ static ssize_t mode_store(struct device *dev, > if (ret) > return ret; > > + 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"); Same nit as in patch #3 that the above string should be indented by 1 more space.