Messages in this thread | | | Date | Tue, 02 Mar 2021 12:11:37 +0530 | From | Sai Prakash Ranjan <> | Subject | Re: [PATCHv2 3/4] coresight: etm4x: Add support to exclude kernel mode tracing |
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On 2021-03-02 04:13, Doug Anderson wrote: > 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> >
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
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