From: Doug Anderson <dianders@chromium.org>
To: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Mike Leach <mike.leach@linaro.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Leo Yan <leo.yan@linaro.org>, Jiri Olsa <jolsa@redhat.com>,
Namhyung Kim <namhyung@kernel.org>,
coresight@lists.linaro.org, Stephen Boyd <swboyd@chromium.org>,
Denis Nikitin <denik@chromium.org>,
Mattias Nissler <mnissler@chromium.org>,
Al Grant <al.grant@arm.com>,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCHv2 3/4] coresight: etm4x: Add support to exclude kernel mode tracing
Date: Mon, 1 Mar 2021 14:43:41 -0800 [thread overview]
Message-ID: <CAD=FV=XCi_+yW6DPeUYmtjMhn-qpjMiB0E4_Qkz6d_e6G-CoVA@mail.gmail.com> (raw)
In-Reply-To: <defd34e2a8744fc93404abdaad2d429fa3f69850.1614624041.git.saiprakash.ranjan@codeaurora.org>
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. ;-)
next prev parent reply other threads:[~2021-03-02 7:42 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-01 19:04 [PATCHv2 0/4] perf/core: Add support to exclude kernel mode PMU tracing Sai Prakash Ranjan
2021-03-01 19:04 ` [PATCHv2 1/4] " Sai Prakash Ranjan
2021-03-01 22:42 ` Doug Anderson
2021-03-01 19:04 ` [PATCHv2 2/4] perf evsel: Print warning for excluding kernel mode instruction tracing Sai Prakash Ranjan
2021-03-01 22:43 ` Doug Anderson
2021-03-02 6:45 ` Sai Prakash Ranjan
2021-03-01 19:04 ` [PATCHv2 3/4] coresight: etm4x: Add support to exclude kernel mode tracing Sai Prakash Ranjan
2021-03-01 22:43 ` Doug Anderson [this message]
2021-03-02 6:41 ` Sai Prakash Ranjan
2021-03-01 19:04 ` [PATCHv2 4/4] coresight: etm3x: " Sai Prakash Ranjan
2021-03-01 22:43 ` Doug Anderson
2021-03-02 6:46 ` Sai Prakash Ranjan
2021-03-04 19:59 ` [PATCHv2 0/4] perf/core: Add support to exclude kernel mode PMU tracing Andi Kleen
2021-03-04 20:17 ` Andi Kleen
2021-03-09 6:38 ` Sai Prakash Ranjan
2021-03-09 14:44 ` Andi Kleen
2021-03-10 15:17 ` Sai Prakash Ranjan
2021-06-10 13:28 ` Mattias Nissler
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