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 for ETMs use the newly introduced kernel config CONFIG_EXCLUDE_KERNEL_HW_ITRACE 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 | 14 +++++++++++++- .../hwtracing/coresight/coresight-etm4x-sysfs.c | 3 ++- 2 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c index b20b6ff17cf6..f94143057bb8 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c @@ -1052,12 +1052,16 @@ static void etm4_set_default(struct etmv4_config *config) return;
/* - * Make default initialisation trace everything + * Make default initialisation trace everything when + * CONFIG_EXCLUDE_KERNEL_HW_ITRACE is disabled. * * This is done by a minimum default config sufficient to enable * full instruction trace - with a default filter for trace all * achieved by having no filtering. */ + if (IS_ENABLED(CONFIG_EXCLUDE_KERNEL_HW_ITRACE)) + config->mode |= ETM_MODE_EXCL_KERN; + etm4_set_default_config(config); etm4_set_default_filter(config); } @@ -1195,6 +1199,7 @@ static int etm4_set_event_filters(struct etmv4_drvdata *drvdata, void etm4_config_trace_mode(struct etmv4_config *config) { u32 mode; + struct etmv4_drvdata *drvdata = container_of(config, struct etmv4_drvdata, config);
mode = config->mode; mode &= (ETM_MODE_EXCL_KERN | ETM_MODE_EXCL_USER); @@ -1202,6 +1207,13 @@ void etm4_config_trace_mode(struct etmv4_config *config) /* excluding kernel AND user space doesn't make sense */ WARN_ON_ONCE(mode == (ETM_MODE_EXCL_KERN | ETM_MODE_EXCL_USER));
+ if (!(mode & ETM_MODE_EXCL_KERN) && IS_ENABLED(CONFIG_EXCLUDE_KERNEL_HW_ITRACE)) { + dev_err(&drvdata->csdev->dev, + "Kernel mode tracing is not allowed, check your kernel config\n"); + config->mode |= ETM_MODE_EXCL_KERN; + return; + } + /* nothing to do if neither flags are set */ if (!(mode & ETM_MODE_EXCL_KERN) && !(mode & ETM_MODE_EXCL_USER)) return; diff --git a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c index 989ce7b8ade7..f1d19d69d151 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c +++ b/drivers/hwtracing/coresight/coresight-etm4x-sysfs.c @@ -426,7 +426,8 @@ static ssize_t mode_store(struct device *dev, else config->vinst_ctrl &= ~BIT(11);
- if (config->mode & (ETM_MODE_EXCL_KERN | ETM_MODE_EXCL_USER)) + if ((config->mode & (ETM_MODE_EXCL_KERN | ETM_MODE_EXCL_USER)) || + IS_ENABLED(CONFIG_EXCLUDE_KERNEL_HW_ITRACE)) etm4_config_trace_mode(config);
spin_unlock(&drvdata->spinlock);