On 2021-03-02 04:13, Doug Anderson wrote:
Hi,
On Mon, Mar 1, 2021 at 11:05 AM Sai Prakash Ranjan
<saiprakash.ranjan@xxxxxxxxxxxxxx> 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@xxxxxxxxxxxx>
Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@xxxxxxxxxxxxxx>
---
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@xxxxxxxxxxxx>
Thanks Doug.
--- 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.
;-)
Ah yes, I will have to post v3 anyways to fix commit message in Patch 2
after I get few more feedback for other patches, I will fix this up as
well.
Thanks,
Sai
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a
member
of Code Aurora Forum, hosted by The Linux Foundation
