The current ETM3x configuration via sysfs can lead to the following inconsistencies:
- If a configuration is modified via sysfs while a perf session is active, the running configuration may differ between before a sched-out and after a subsequent sched-in.
To resolve these issues, separate the configuration into:
- active_config: the configuration applied to the current session - config: the configuration set via sysfs
Additionally:
- Since active_config and related fields are accessed only by the local CPU in etm_enable/disable_sysfs_smp_call() (similar to perf enable/disable), remove the lock/unlock from the sysfs enable/disable path and starting/dying_cpu path except when to access config fields only.
Fixes: 1925a470ce69 ("coresight: etm3x: splitting struct etm_drvdata") Signed-off-by: Yeoreum Yun yeoreum.yun@arm.com --- drivers/hwtracing/coresight/coresight-etm.h | 2 + .../coresight/coresight-etm3x-core.c | 38 +++++++++---------- 2 files changed, 21 insertions(+), 19 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-etm.h b/drivers/hwtracing/coresight/coresight-etm.h index 932bec82fb47..01f1a7f2559c 100644 --- a/drivers/hwtracing/coresight/coresight-etm.h +++ b/drivers/hwtracing/coresight/coresight-etm.h @@ -243,6 +243,7 @@ struct etm_config { * @boot_enable:true if we should start tracing at boot time. * @os_unlock: true if access to management registers is allowed. * @traceid: value of the current ID for this component. + * @active_config: structure holding current running configuration parameters. * @config: structure holding configuration parameters. */ struct etm_drvdata { @@ -258,6 +259,7 @@ struct etm_drvdata { bool boot_enable; bool os_unlock; u32 traceid; + struct etm_config active_config; struct etm_config config; };
diff --git a/drivers/hwtracing/coresight/coresight-etm3x-core.c b/drivers/hwtracing/coresight/coresight-etm3x-core.c index ccfde9eda537..ed27e35b42ec 100644 --- a/drivers/hwtracing/coresight/coresight-etm3x-core.c +++ b/drivers/hwtracing/coresight/coresight-etm3x-core.c @@ -309,7 +309,7 @@ static int etm_parse_event_config(struct etm_drvdata *drvdata, struct perf_event *event) { const struct etm_caps *caps = &drvdata->caps; - struct etm_config *config = &drvdata->config; + struct etm_config *config = &drvdata->active_config; struct perf_event_attr *attr = &event->attr; u8 ts_level;
@@ -368,7 +368,7 @@ static int etm_enable_hw(struct etm_drvdata *drvdata) int i, rc; u32 etmcr; const struct etm_caps *caps = &drvdata->caps; - struct etm_config *config = &drvdata->config; + struct etm_config *config = &drvdata->active_config; struct coresight_device *csdev = drvdata->csdev;
CS_UNLOCK(drvdata->csa.base); @@ -443,24 +443,30 @@ static int etm_enable_hw(struct etm_drvdata *drvdata) struct etm_enable_arg { struct etm_drvdata *drvdata; struct coresight_path *path; + struct etm_config config; int rc; };
static void etm_enable_sysfs_smp_call(void *info) { struct etm_enable_arg *arg = info; + struct etm_drvdata *drvdata; struct coresight_device *csdev;
if (WARN_ON(!arg)) return;
- csdev = arg->drvdata->csdev; + drvdata = arg->drvdata; + csdev = drvdata->csdev; if (!coresight_take_mode(csdev, CS_MODE_SYSFS)) { /* Someone is already using the tracer */ arg->rc = -EBUSY; return; }
+ drvdata->active_config = arg->config; + drvdata->traceid = arg->path->trace_id; + arg->rc = etm_enable_hw(arg->drvdata);
/* The tracer didn't start */ @@ -469,6 +475,7 @@ static void etm_enable_sysfs_smp_call(void *info) return; }
+ drvdata->sticky_enable = true; csdev->path = arg->path; }
@@ -513,10 +520,6 @@ static int etm_enable_sysfs(struct coresight_device *csdev, struct coresight_pat struct etm_enable_arg arg = { }; int ret;
- raw_spin_lock(&drvdata->spinlock); - - drvdata->traceid = path->trace_id; - /* * Configure the ETM only if the CPU is online. If it isn't online * hw configuration will take place on the local CPU during bring up. @@ -524,23 +527,24 @@ static int etm_enable_sysfs(struct coresight_device *csdev, struct coresight_pat if (cpu_online(drvdata->cpu)) { arg.drvdata = drvdata; arg.path = path; + + raw_spin_lock(&drvdata->spinlock); + arg.config = drvdata->config; + raw_spin_unlock(&drvdata->spinlock); + ret = smp_call_function_single(drvdata->cpu, etm_enable_sysfs_smp_call, &arg, 1); if (!ret) ret = arg.rc; - if (!ret) - drvdata->sticky_enable = true; } else { ret = -ENODEV; }
- if (ret) - etm_release_trace_id(drvdata); - - raw_spin_unlock(&drvdata->spinlock); - if (!ret) dev_dbg(&csdev->dev, "ETM tracing enabled\n"); + else + etm_release_trace_id(drvdata); + return ret; }
@@ -567,7 +571,7 @@ static void etm_disable_hw(struct etm_drvdata *drvdata) { int i; const struct etm_caps *caps = &drvdata->caps; - struct etm_config *config = &drvdata->config; + struct etm_config *config = &drvdata->active_config; struct coresight_device *csdev = drvdata->csdev;
CS_UNLOCK(drvdata->csa.base); @@ -633,8 +637,6 @@ static void etm_disable_sysfs(struct coresight_device *csdev) { struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
- raw_spin_lock(&drvdata->spinlock); - /* * Executing etm_disable_hw on the cpu whose ETM is being disabled * ensures that register writes occur when cpu is powered. @@ -642,8 +644,6 @@ static void etm_disable_sysfs(struct coresight_device *csdev) smp_call_function_single(drvdata->cpu, etm_disable_sysfs_smp_call, drvdata, 1);
- raw_spin_unlock(&drvdata->spinlock); - /* * we only release trace IDs when resetting sysfs. * This permits sysfs users to read the trace ID after the trace